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src/os_unix.c
8 582 строки
289 KB
drh
Improvements to the unix temporary filename generator so that it continues
22 июл 2026, 14:24
22 июл 2026, 14:24
33510c5
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/* ** 2004 May 22 ** ** The author disclaims copyright to this source code. In place of ** a legal notice, here is a blessing: ** ** May you do good and not evil. ** May you find forgiveness for yourself and forgive others. ** May you share freely, never taking more than you give. ** ****************************************************************************** ** ** This file contains the VFS implementation for unix-like operating systems ** include Linux, MacOSX, *BSD, QNX, VxWorks, AIX, HPUX, and others. ** ** There are actually several different VFS implementations in this file. ** The differences are in the way that file locking is done. The default ** implementation uses Posix Advisory Locks. Alternative implementations ** use flock(), dot-files, various proprietary locking schemas, or simply ** skip locking all together. ** ** This source file is organized into divisions where the logic for various ** subfunctions is contained within the appropriate division. PLEASE ** KEEP THE STRUCTURE OF THIS FILE INTACT. New code should be placed ** in the correct division and should be clearly labelled. ** ** The layout of divisions is as follows: ** ** * General-purpose declarations and utility functions. ** * Unique file ID logic used by VxWorks. ** * Various locking primitive implementations (all except proxy locking): ** + for Posix Advisory Locks ** + for no-op locks ** + for dot-file locks ** + for flock() locking ** + for named semaphore locks (VxWorks only) ** + for AFP filesystem locks (MacOSX only) ** * sqlite3_file methods not associated with locking. ** * Definitions of sqlite3_io_methods objects for all locking ** methods plus "finder" functions for each locking method. ** * sqlite3_vfs method implementations. ** * Locking primitives for the proxy uber-locking-method. (MacOSX only) ** * Definitions of sqlite3_vfs objects for all locking methods ** plus implementations of sqlite3_os_init() and sqlite3_os_end(). */ #include "sqliteInt.h" #if SQLITE_OS_UNIX /* This file is used on unix only */ /* ** There are various methods for file locking used for concurrency ** control: ** ** 1. POSIX locking (the default), ** 2. No locking, ** 3. Dot-file locking, ** 4. flock() locking, ** 5. AFP locking (OSX only), ** 6. Named POSIX semaphores (VXWorks only), ** 7. proxy locking. (OSX only) ** ** Styles 4, 5, and 7 are only available of SQLITE_ENABLE_LOCKING_STYLE ** is defined to 1. The SQLITE_ENABLE_LOCKING_STYLE also enables automatic ** selection of the appropriate locking style based on the filesystem ** where the database is located. */ #if !defined(SQLITE_ENABLE_LOCKING_STYLE) # if defined(__APPLE__) # define SQLITE_ENABLE_LOCKING_STYLE 1 # else # define SQLITE_ENABLE_LOCKING_STYLE 0 # endif #endif /* Use pread() and pwrite() if they are available */ #if defined(__APPLE__) || defined(__linux__) # define HAVE_PREAD 1 # define HAVE_PWRITE 1 #endif #if defined(HAVE_PREAD64) && defined(HAVE_PWRITE64) # undef USE_PREAD # define USE_PREAD64 1 #elif defined(HAVE_PREAD) && defined(HAVE_PWRITE) # undef USE_PREAD64 # define USE_PREAD 1 #endif /* ** standard include files. */ #include <sys/types.h> /* amalgamator: keep */ #include <sys/stat.h> /* amalgamator: keep */ #include <fcntl.h> #include <sys/ioctl.h> #include <unistd.h> /* amalgamator: keep */ #include <time.h> #include <sys/time.h> /* amalgamator: keep */ #include <errno.h> #if (!defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0) \ && !defined(SQLITE_WASI) # include <sys/mman.h> #endif #if SQLITE_ENABLE_LOCKING_STYLE # include <sys/ioctl.h> # include <sys/file.h> # include <sys/param.h> #endif /* SQLITE_ENABLE_LOCKING_STYLE */ /* ** Try to determine if gethostuuid() is available based on standard ** macros. This might sometimes compute the wrong value for some ** obscure platforms. For those cases, simply compile with one of ** the following: ** ** -DHAVE_GETHOSTUUID=0 ** -DHAVE_GETHOSTUUID=1 ** ** None if this matters except when building on Apple products with ** -DSQLITE_ENABLE_LOCKING_STYLE. */ #ifndef HAVE_GETHOSTUUID # define HAVE_GETHOSTUUID 0 # if defined(__APPLE__) && ((__MAC_OS_X_VERSION_MIN_REQUIRED > 1050) || \ (__IPHONE_OS_VERSION_MIN_REQUIRED > 2000)) # if (!defined(TARGET_OS_EMBEDDED) || (TARGET_OS_EMBEDDED==0)) \ && (!defined(TARGET_IPHONE_SIMULATOR) || (TARGET_IPHONE_SIMULATOR==0))\ && (!defined(TARGET_OS_MACCATALYST) || (TARGET_OS_MACCATALYST==0)) # undef HAVE_GETHOSTUUID # define HAVE_GETHOSTUUID 1 # else # warning "gethostuuid() is disabled." # endif # endif #endif #if OS_VXWORKS # include <sys/ioctl.h> # include <semaphore.h> # include <limits.h> #endif /* OS_VXWORKS */ #if defined(__APPLE__) || SQLITE_ENABLE_LOCKING_STYLE # include <sys/mount.h> #endif #ifdef HAVE_UTIME # include <utime.h> #endif /* ** Allowed values of unixFile.fsFlags */ #define SQLITE_FSFLAGS_IS_MSDOS 0x1 /* ** If we are to be thread-safe, include the pthreads header. */ #if SQLITE_THREADSAFE # include <pthread.h> #endif /* ** Default permissions when creating a new file */ #ifndef SQLITE_DEFAULT_FILE_PERMISSIONS # define SQLITE_DEFAULT_FILE_PERMISSIONS 0644 #endif /* ** Default permissions when creating auto proxy dir */ #ifndef SQLITE_DEFAULT_PROXYDIR_PERMISSIONS # define SQLITE_DEFAULT_PROXYDIR_PERMISSIONS 0755 #endif /* ** Maximum supported path-length. */ #define MAX_PATHNAME 512 /* ** Maximum supported symbolic links */ #define SQLITE_MAX_SYMLINKS 100 /* ** Remove and stub certain info for WASI (WebAssembly System ** Interface) builds. */ #ifdef SQLITE_WASI # undef HAVE_FCHMOD # undef HAVE_FCHOWN # undef HAVE_MREMAP # define HAVE_MREMAP 0 # ifndef SQLITE_DEFAULT_UNIX_VFS # define SQLITE_DEFAULT_UNIX_VFS "unix-dotfile" /* ^^^ should SQLITE_DEFAULT_UNIX_VFS be "unix-none"? */ # endif # ifndef F_RDLCK # define F_RDLCK 0 # define F_WRLCK 1 # define F_UNLCK 2 # if __LONG_MAX == 0x7fffffffL # define F_GETLK 12 # define F_SETLK 13 # define F_SETLKW 14 # else # define F_GETLK 5 # define F_SETLK 6 # define F_SETLKW 7 # endif # endif #else /* !SQLITE_WASI */ # ifndef HAVE_FCHMOD # define HAVE_FCHMOD 1 # endif #endif /* SQLITE_WASI */ #ifdef SQLITE_WASI # define osGetpid(X) (pid_t)1 #else /* Always cast the getpid() return type for compatibility with ** kernel modules in VxWorks. */ # define osGetpid(X) (pid_t)getpid() #endif /* ** Only set the lastErrno if the error code is a real error and not ** a normal expected return code of SQLITE_BUSY or SQLITE_OK */ #define IS_LOCK_ERROR(x) ((x != SQLITE_OK) && (x != SQLITE_BUSY)) /* Forward references */ typedef struct unixShm unixShm; /* Connection shared memory */ typedef struct unixShmNode unixShmNode; /* Shared memory instance */ typedef struct unixInodeInfo unixInodeInfo; /* An i-node */ typedef struct UnixUnusedFd UnixUnusedFd; /* An unused file descriptor */ /* ** Sometimes, after a file handle is closed by SQLite, the file descriptor ** cannot be closed immediately. In these cases, instances of the following ** structure are used to store the file descriptor while waiting for an ** opportunity to either close or reuse it. */ struct UnixUnusedFd { int fd; /* File descriptor to close */ int flags; /* Flags this file descriptor was opened with */ UnixUnusedFd *pNext; /* Next unused file descriptor on same file */ }; /* ** The unixFile structure is subclass of sqlite3_file specific to the unix ** VFS implementations. */ typedef struct unixFile unixFile; struct unixFile { sqlite3_io_methods const *pMethod; /* Always the first entry */ sqlite3_vfs *pVfs; /* The VFS that created this unixFile */ unixInodeInfo *pInode; /* Info about locks on this inode */ int h; /* The file descriptor */ unsigned char eFileLock; /* The type of lock held on this fd */ unsigned short int ctrlFlags; /* Behavioral bits. UNIXFILE_* flags */ int lastErrno; /* The unix errno from last I/O error */ void *lockingContext; /* Locking style specific state */ UnixUnusedFd *pPreallocatedUnused; /* Pre-allocated UnixUnusedFd */ const char *zPath; /* Name of the file */ unixShm *pShm; /* Shared memory segment information */ int szChunk; /* Configured by FCNTL_CHUNK_SIZE */ #if SQLITE_MAX_MMAP_SIZE>0 int nFetchOut; /* Number of outstanding xFetch refs */ sqlite3_int64 mmapSize; /* Usable size of mapping at pMapRegion */ sqlite3_int64 mmapSizeActual; /* Actual size of mapping at pMapRegion */ sqlite3_int64 mmapSizeMax; /* Configured FCNTL_MMAP_SIZE value */ void *pMapRegion; /* Memory mapped region */ #endif int sectorSize; /* Device sector size */ int deviceCharacteristics; /* Precomputed device characteristics */ #if SQLITE_ENABLE_LOCKING_STYLE int openFlags; /* The flags specified at open() */ #endif #if SQLITE_ENABLE_LOCKING_STYLE || defined(__APPLE__) unsigned fsFlags; /* cached details from statfs() */ #endif #ifdef SQLITE_ENABLE_SETLK_TIMEOUT unsigned iBusyTimeout; /* Wait this many millisec on locks */ int bBlockOnConnect; /* True to block for SHARED locks */ #endif #if OS_VXWORKS struct vxworksFileId *pId; /* Unique file ID */ #endif #ifdef SQLITE_DEBUG /* The next group of variables are used to track whether or not the ** transaction counter in bytes 24-27 of database files are updated ** whenever any part of the database changes. An assertion fault will ** occur if a file is updated without also updating the transaction ** counter. This test is made to avoid new problems similar to the ** one described by ticket #3584. */ unsigned char transCntrChng; /* True if the transaction counter changed */ unsigned char dbUpdate; /* True if any part of database file changed */ unsigned char inNormalWrite; /* True if in a normal write operation */ #endif #ifdef SQLITE_TEST /* In test mode, increase the size of this structure a bit so that ** it is larger than the struct CrashFile defined in test6.c. */ char aPadding[32]; #endif }; /* This variable holds the process id (pid) from when the xRandomness() ** method was called. If xOpen() is called from a different process id, ** indicating that a fork() has occurred, the PRNG will be reset. */ static pid_t randomnessPid = 0; /* ** Allowed values for the unixFile.ctrlFlags bitmask: */ #define UNIXFILE_EXCL 0x01 /* Connections from one process only */ #define UNIXFILE_RDONLY 0x02 /* Connection is read only */ #define UNIXFILE_PERSIST_WAL 0x04 /* Persistent WAL mode */ #if !defined(SQLITE_DISABLE_DIRSYNC) && !defined(_AIX) # define UNIXFILE_DIRSYNC 0x08 /* Directory sync needed */ #else # define UNIXFILE_DIRSYNC 0x00 #endif #define UNIXFILE_PSOW 0x10 /* SQLITE_IOCAP_POWERSAFE_OVERWRITE */ #define UNIXFILE_DELETE 0x20 /* Delete on close */ #define UNIXFILE_URI 0x40 /* Filename might have query parameters */ #define UNIXFILE_NOLOCK 0x80 /* Do no file locking */ /* ** Include code that is common to all os_*.c files */ #include "os_common.h" /* ** Define various macros that are missing from some systems. */ #ifndef O_LARGEFILE # define O_LARGEFILE 0 #endif #ifdef SQLITE_DISABLE_LFS # undef O_LARGEFILE # define O_LARGEFILE 0 #endif #ifndef O_NOFOLLOW # define O_NOFOLLOW 0 #endif #ifndef O_BINARY # define O_BINARY 0 #endif /* ** The threadid macro resolves to the thread-id or to 0. Used for ** testing and debugging only. */ #if SQLITE_THREADSAFE #define threadid pthread_self() #else #define threadid 0 #endif /* ** HAVE_MREMAP defaults to true on Linux and false everywhere else. */ #if !defined(HAVE_MREMAP) # if defined(__linux__) && defined(_GNU_SOURCE) # define HAVE_MREMAP 1 # else # define HAVE_MREMAP 0 # endif #endif /* ** Explicitly call the 64-bit version of lseek() on Android. Otherwise, lseek() ** is the 32-bit version, even if _FILE_OFFSET_BITS=64 is defined. */ #ifdef __ANDROID__ # define lseek lseek64 #endif #ifdef __linux__ /* ** Linux-specific IOCTL magic numbers used for controlling F2FS */ #define F2FS_IOCTL_MAGIC 0xf5 #define F2FS_IOC_START_ATOMIC_WRITE _IO(F2FS_IOCTL_MAGIC, 1) #define F2FS_IOC_COMMIT_ATOMIC_WRITE _IO(F2FS_IOCTL_MAGIC, 2) #define F2FS_IOC_START_VOLATILE_WRITE _IO(F2FS_IOCTL_MAGIC, 3) #define F2FS_IOC_ABORT_VOLATILE_WRITE _IO(F2FS_IOCTL_MAGIC, 5) #define F2FS_IOC_GET_FEATURES _IOR(F2FS_IOCTL_MAGIC, 12, u32) #define F2FS_FEATURE_ATOMIC_WRITE 0x0004 #endif /* __linux__ */ /* ** Different Unix systems declare open() in different ways. Same use ** open(const char*,int,mode_t). Others use open(const char*,int,...). ** The difference is important when using a pointer to the function. ** ** The safest way to deal with the problem is to always use this wrapper ** which always has the same well-defined interface. */ static int posixOpen(const char *zFile, int flags, int mode){ return open(zFile, flags, mode); } /* Forward reference */ static int openDirectory(const char*, int*); static int unixGetpagesize(void); /* ** Many system calls are accessed through pointer-to-functions so that ** they may be overridden at runtime to facilitate fault injection during ** testing and sandboxing. The following array holds the names and pointers ** to all overrideable system calls. */ static struct unix_syscall { const char *zName; /* Name of the system call */ sqlite3_syscall_ptr pCurrent; /* Current value of the system call */ sqlite3_syscall_ptr pDefault; /* Default value */ } aSyscall[] = { { "open", (sqlite3_syscall_ptr)posixOpen, 0 }, #define osOpen ((int(*)(const char*,int,int))aSyscall[0].pCurrent) { "close", (sqlite3_syscall_ptr)close, 0 }, #define osClose ((int(*)(int))aSyscall[1].pCurrent) { "access", (sqlite3_syscall_ptr)access, 0 }, #define osAccess ((int(*)(const char*,int))aSyscall[2].pCurrent) { "getcwd", (sqlite3_syscall_ptr)getcwd, 0 }, #define osGetcwd ((char*(*)(char*,size_t))aSyscall[3].pCurrent) { "stat", (sqlite3_syscall_ptr)stat, 0 }, #define osStat ((int(*)(const char*,struct stat*))aSyscall[4].pCurrent) /* ** The DJGPP compiler environment looks mostly like Unix, but it ** lacks the fcntl() system call. So redefine fcntl() to be something ** that always succeeds. This means that locking does not occur under ** DJGPP. But it is DOS - what did you expect? */ #ifdef __DJGPP__ { "fstat", 0, 0 }, #define osFstat(a,b,c) 0 #else { "fstat", (sqlite3_syscall_ptr)fstat, 0 }, #define osFstat ((int(*)(int,struct stat*))aSyscall[5].pCurrent) #endif { "ftruncate", (sqlite3_syscall_ptr)ftruncate, 0 }, #define osFtruncate ((int(*)(int,off_t))aSyscall[6].pCurrent) { "fcntl", (sqlite3_syscall_ptr)fcntl, 0 }, #define osFcntl ((int(*)(int,int,...))aSyscall[7].pCurrent) { "read", (sqlite3_syscall_ptr)read, 0 }, #define osRead ((ssize_t(*)(int,void*,size_t))aSyscall[8].pCurrent) #if defined(USE_PREAD) || SQLITE_ENABLE_LOCKING_STYLE { "pread", (sqlite3_syscall_ptr)pread, 0 }, #else { "pread", (sqlite3_syscall_ptr)0, 0 }, #endif #define osPread ((ssize_t(*)(int,void*,size_t,off_t))aSyscall[9].pCurrent) #if defined(USE_PREAD64) { "pread64", (sqlite3_syscall_ptr)pread64, 0 }, #else { "pread64", (sqlite3_syscall_ptr)0, 0 }, #endif #define osPread64 ((ssize_t(*)(int,void*,size_t,off64_t))aSyscall[10].pCurrent) { "write", (sqlite3_syscall_ptr)write, 0 }, #define osWrite ((ssize_t(*)(int,const void*,size_t))aSyscall[11].pCurrent) #if defined(USE_PREAD) || SQLITE_ENABLE_LOCKING_STYLE { "pwrite", (sqlite3_syscall_ptr)pwrite, 0 }, #else { "pwrite", (sqlite3_syscall_ptr)0, 0 }, #endif #define osPwrite ((ssize_t(*)(int,const void*,size_t,off_t))\ aSyscall[12].pCurrent) #if defined(USE_PREAD64) { "pwrite64", (sqlite3_syscall_ptr)pwrite64, 0 }, #else { "pwrite64", (sqlite3_syscall_ptr)0, 0 }, #endif #define osPwrite64 ((ssize_t(*)(int,const void*,size_t,off64_t))\ aSyscall[13].pCurrent) #if defined(HAVE_FCHMOD) { "fchmod", (sqlite3_syscall_ptr)fchmod, 0 }, #define osFchmod ((int(*)(int,mode_t))aSyscall[14].pCurrent) #else { "fchmod", (sqlite3_syscall_ptr)0, 0 }, #define osFchmod(FID,MODE) 0 #endif #if defined(HAVE_POSIX_FALLOCATE) && HAVE_POSIX_FALLOCATE { "fallocate", (sqlite3_syscall_ptr)posix_fallocate, 0 }, #else { "fallocate", (sqlite3_syscall_ptr)0, 0 }, #endif #define osFallocate ((int(*)(int,off_t,off_t))aSyscall[15].pCurrent) { "unlink", (sqlite3_syscall_ptr)unlink, 0 }, #define osUnlink ((int(*)(const char*))aSyscall[16].pCurrent) { "openDirectory", (sqlite3_syscall_ptr)openDirectory, 0 }, #define osOpenDirectory ((int(*)(const char*,int*))aSyscall[17].pCurrent) { "mkdir", (sqlite3_syscall_ptr)mkdir, 0 }, #define osMkdir ((int(*)(const char*,mode_t))aSyscall[18].pCurrent) { "rmdir", (sqlite3_syscall_ptr)rmdir, 0 }, #define osRmdir ((int(*)(const char*))aSyscall[19].pCurrent) #if defined(HAVE_FCHOWN) { "fchown", (sqlite3_syscall_ptr)fchown, 0 }, #else { "fchown", (sqlite3_syscall_ptr)0, 0 }, #endif #define osFchown ((int(*)(int,uid_t,gid_t))aSyscall[20].pCurrent) #if defined(HAVE_FCHOWN) { "geteuid", (sqlite3_syscall_ptr)geteuid, 0 }, #else { "geteuid", (sqlite3_syscall_ptr)0, 0 }, #endif #define osGeteuid ((uid_t(*)(void))aSyscall[21].pCurrent) #if (!defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0) \ && !defined(SQLITE_WASI) { "mmap", (sqlite3_syscall_ptr)mmap, 0 }, #else { "mmap", (sqlite3_syscall_ptr)0, 0 }, #endif #define osMmap ((void*(*)(void*,size_t,int,int,int,off_t))aSyscall[22].pCurrent) #if (!defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0) \ && !defined(SQLITE_WASI) { "munmap", (sqlite3_syscall_ptr)munmap, 0 }, #else { "munmap", (sqlite3_syscall_ptr)0, 0 }, #endif #define osMunmap ((int(*)(void*,size_t))aSyscall[23].pCurrent) #if HAVE_MREMAP && (!defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0) { "mremap", (sqlite3_syscall_ptr)mremap, 0 }, #else { "mremap", (sqlite3_syscall_ptr)0, 0 }, #endif #define osMremap ((void*(*)(void*,size_t,size_t,int,...))aSyscall[24].pCurrent) #if !defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0 { "getpagesize", (sqlite3_syscall_ptr)unixGetpagesize, 0 }, #else { "getpagesize", (sqlite3_syscall_ptr)0, 0 }, #endif #define osGetpagesize ((int(*)(void))aSyscall[25].pCurrent) #if defined(HAVE_READLINK) { "readlink", (sqlite3_syscall_ptr)readlink, 0 }, #else { "readlink", (sqlite3_syscall_ptr)0, 0 }, #endif #define osReadlink ((ssize_t(*)(const char*,char*,size_t))aSyscall[26].pCurrent) #if defined(HAVE_LSTAT) { "lstat", (sqlite3_syscall_ptr)lstat, 0 }, #else { "lstat", (sqlite3_syscall_ptr)0, 0 }, #endif #define osLstat ((int(*)(const char*,struct stat*))aSyscall[27].pCurrent) #if defined(__linux__) && defined(SQLITE_ENABLE_BATCH_ATOMIC_WRITE) # ifdef __ANDROID__ { "ioctl", (sqlite3_syscall_ptr)(int(*)(int, int, ...))ioctl, 0 }, #define osIoctl ((int(*)(int,int,...))aSyscall[28].pCurrent) # else { "ioctl", (sqlite3_syscall_ptr)ioctl, 0 }, #define osIoctl ((int(*)(int,unsigned long,...))aSyscall[28].pCurrent) # endif #else { "ioctl", (sqlite3_syscall_ptr)0, 0 }, #endif }; /* End of the overrideable system calls */ #if defined(SQLITE_DEBUG) || defined(SQLITE_ENABLE_FILESTAT) /* ** Extract Posix Advisory Locking information about file description fd ** from the /proc/PID/fdinfo/FD pseudo-file. Fill the string buffer a[16] ** with characters to indicate which SQLite-relevant locks are held. ** a[16] will be a 15-character zero-terminated string with the following ** schema: ** ** AAA/B.DDD.DDDDD ** ** Each of character A-D will be "w" or "r" or "-" to indicate either a ** write-lock, a read-lock, or no-lock, respectively. The "." and "/" ** characters are delimiters intended to make the string more easily ** readable by humans. Here are the meaning of the specific letters: ** ** AAA -> The main database locks. PENDING_BYTE, RESERVED_BYTE, ** and SHARED_FIRST, respectively. ** ** B -> The deadman switch lock. Offset 128 of the -shm file. ** ** CCC -> WAL locks: WRITE, CKPT, RECOVER ** ** DDDDD -> WAL read-locks 0 through 5 ** ** Note that elements before the "/" apply to the main database file and ** elements after the "/" apply to the -shm file in WAL mode. ** ** Here is another way of thinking about the meaning of the result string: ** ** AAA/B.CCC.DDDDD ** ||| | ||| \___/ ** PENDING--'|| | ||| `----- READ 0-5 ** RESERVED--'| | ||`---- RECOVER ** SHARED ----' | |`----- CKPT ** DMS ------' `------ WRITE ** ** Return SQLITE_OK on success and SQLITE_ERROR_UNABLE if the /proc ** pseudo-filesystem is unavailable. */ static int unixPosixAdvisoryLocks( int fd, /* The file descriptor to analyze */ char a[16] /* Write a text description of PALs here */ ){ int in; ssize_t n; char *p, *pNext, *x; char z[2000]; /* 1 */ /* 012 4 678 01234 */ memcpy(a, "---/-.---.-----", 16); sqlite3_snprintf(sizeof(z), z, "/proc/%d/fdinfo/%d", getpid(), fd); in = osOpen(z, O_RDONLY, 0); if( in<0 ){ return SQLITE_ERROR_UNABLE; } n = osRead(in, z, sizeof(z)-1); osClose(in); if( n<=0 ) return SQLITE_ERROR_UNABLE; z[n] = 0; /* We are looking for lines that begin with "lock:\t". Examples: ** ** lock: 1: POSIX ADVISORY READ 494716 08:02:5277597 1073741826 1073742335 ** lock: 1: POSIX ADVISORY WRITE 494716 08:02:5282282 120 120 ** lock: 2: POSIX ADVISORY READ 494716 08:02:5282282 123 123 ** lock: 3: POSIX ADVISORY READ 494716 08:02:5282282 128 128 */ pNext = strstr(z, "lock:\t"); while( pNext ){ char cType = 0; sqlite3_int64 iFirst, iLast; p = pNext+6; pNext = strstr(p, "lock:\t"); if( pNext ) pNext[-1] = 0; if( (x = strstr(p, " READ "))!=0 ){ cType = 'r'; x += 6; }else if( (x = strstr(p, " WRITE "))!=0 ){ cType = 'w'; x += 7; }else{ continue; } x = strrchr(x, ' '); if( x==0 ) continue; iLast = strtoll(x+1, 0, 10); *x = 0; x = strrchr(p, ' '); if( x==0 ) continue; iFirst = strtoll(x+1, 0, 10); if( iLast>=PENDING_BYTE ){ if( iFirst<=PENDING_BYTE && iLast>=PENDING_BYTE ) a[0] = cType; if( iFirst<=PENDING_BYTE+1 && iLast>=PENDING_BYTE+1 ) a[1] = cType; if( iFirst<=PENDING_BYTE+2 && iLast>=PENDING_BYTE+510 ) a[2] = cType; }else if( iLast<=128 ){ if( iFirst<=128 && iLast>=128 ) a[4] = cType; if( iFirst<=120 && iLast>=120 ) a[6] = cType; if( iFirst<=121 && iLast>=121 ) a[7] = cType; if( iFirst<=122 && iLast>=122 ) a[8] = cType; if( iFirst<=123 && iLast>=123 ) a[10] = cType; if( iFirst<=124 && iLast>=124 ) a[11] = cType; if( iFirst<=125 && iLast>=125 ) a[12] = cType; if( iFirst<=126 && iLast>=126 ) a[13] = cType; if( iFirst<=127 && iLast>=127 ) a[14] = cType; } } return SQLITE_OK; } #else # define unixPosixAdvisoryLocks(A,B) SQLITE_ERROR_UNABLE #endif /* SQLITE_DEBUG || SQLITE_ENABLE_FILESTAT */ /* ** On some systems, calls to fchown() will trigger a message in a security ** log if they come from non-root processes. So avoid calling fchown() if ** we are not running as root. */ static int robustFchown(int fd, uid_t uid, gid_t gid){ #if defined(HAVE_FCHOWN) return osGeteuid() ? 0 : osFchown(fd,uid,gid); #else return 0; #endif } /* ** This is the xSetSystemCall() method of sqlite3_vfs for all of the ** "unix" VFSes. Return SQLITE_OK upon successfully updating the ** system call pointer, or SQLITE_NOTFOUND if there is no configurable ** system call named zName. */ static int unixSetSystemCall( sqlite3_vfs *pNotUsed, /* The VFS pointer. Not used */ const char *zName, /* Name of system call to override */ sqlite3_syscall_ptr pNewFunc /* Pointer to new system call value */ ){ unsigned int i; int rc = SQLITE_NOTFOUND; UNUSED_PARAMETER(pNotUsed); if( zName==0 ){ /* If no zName is given, restore all system calls to their default ** settings and return NULL */ rc = SQLITE_OK; for(i=0; i<sizeof(aSyscall)/sizeof(aSyscall[0]); i++){ if( aSyscall[i].pDefault ){ aSyscall[i].pCurrent = aSyscall[i].pDefault; } } }else{ /* If zName is specified, operate on only the one system call ** specified. */ for(i=0; i<sizeof(aSyscall)/sizeof(aSyscall[0]); i++){ if( strcmp(zName, aSyscall[i].zName)==0 ){ if( aSyscall[i].pDefault==0 ){ aSyscall[i].pDefault = aSyscall[i].pCurrent; } rc = SQLITE_OK; if( pNewFunc==0 ) pNewFunc = aSyscall[i].pDefault; aSyscall[i].pCurrent = pNewFunc; break; } } } return rc; } /* ** Return the value of a system call. Return NULL if zName is not a ** recognized system call name. NULL is also returned if the system call ** is currently undefined. */ static sqlite3_syscall_ptr unixGetSystemCall( sqlite3_vfs *pNotUsed, const char *zName ){ unsigned int i; UNUSED_PARAMETER(pNotUsed); for(i=0; i<sizeof(aSyscall)/sizeof(aSyscall[0]); i++){ if( strcmp(zName, aSyscall[i].zName)==0 ) return aSyscall[i].pCurrent; } return 0; } /* ** Return the name of the first system call after zName. If zName==NULL ** then return the name of the first system call. Return NULL if zName ** is the last system call or if zName is not the name of a valid ** system call. */ static const char *unixNextSystemCall(sqlite3_vfs *p, const char *zName){ int i = -1; UNUSED_PARAMETER(p); if( zName ){ for(i=0; i<ArraySize(aSyscall)-1; i++){ if( strcmp(zName, aSyscall[i].zName)==0 ) break; } } for(i++; i<ArraySize(aSyscall); i++){ if( aSyscall[i].pCurrent!=0 ) return aSyscall[i].zName; } return 0; } /* ** Do not accept any file descriptor less than this value, in order to avoid ** opening database file using file descriptors that are commonly used for ** standard input, output, and error. */ #ifndef SQLITE_MINIMUM_FILE_DESCRIPTOR # define SQLITE_MINIMUM_FILE_DESCRIPTOR 3 #endif /* ** Invoke open(). Do so multiple times, until it either succeeds or ** fails for some reason other than EINTR. ** ** If the file creation mode "m" is 0 then set it to the default for ** SQLite. The default is SQLITE_DEFAULT_FILE_PERMISSIONS (normally ** 0644) as modified by the system umask. If m is not 0, then ** make the file creation mode be exactly m ignoring the umask. ** ** The m parameter will be non-zero only when creating -wal, -journal, ** and -shm files. We want those files to have *exactly* the same ** permissions as their original database, unadulterated by the umask. ** In that way, if a database file is -rw-rw-rw or -rw-rw-r-, and a ** transaction crashes and leaves behind hot journals, then any ** process that is able to write to the database will also be able to ** recover the hot journals. */ static int robust_open(const char *z, int f, mode_t m){ int fd; mode_t m2 = m ? m : SQLITE_DEFAULT_FILE_PERMISSIONS; while(1){ #if defined(O_CLOEXEC) fd = osOpen(z,f|O_CLOEXEC,m2); #else fd = osOpen(z,f,m2); #endif if( fd<0 ){ if( errno==EINTR ) continue; break; } if( fd>=SQLITE_MINIMUM_FILE_DESCRIPTOR ) break; if( (f & (O_EXCL|O_CREAT))==(O_EXCL|O_CREAT) ){ (void)osUnlink(z); } osClose(fd); sqlite3_log(SQLITE_WARNING, "attempt to open \"%s\" as file descriptor %d", z, fd); fd = -1; if( osOpen("/dev/null", O_RDONLY, m)<0 ) break; } if( fd>=0 ){ if( m!=0 ){ struct stat statbuf; if( osFstat(fd, &statbuf)==0 && statbuf.st_size==0 && (statbuf.st_mode&0777)!=m ){ osFchmod(fd, m); } } #if defined(FD_CLOEXEC) && (!defined(O_CLOEXEC) || O_CLOEXEC==0) osFcntl(fd, F_SETFD, osFcntl(fd, F_GETFD, 0) | FD_CLOEXEC); #endif } return fd; } /* ** Helper functions to obtain and relinquish the global mutex. The ** global mutex is used to protect the unixInodeInfo objects used by ** this file, all of which may be shared by multiple threads. ** ** Function unixMutexHeld() is used to assert() that the global mutex ** is held when required. This function is only used as part of assert() ** statements. e.g. ** ** unixEnterMutex() ** assert( unixMutexHeld() ); ** unixEnterLeave() ** ** To prevent deadlock, the global unixBigLock must must be acquired ** before the unixInodeInfo.pLockMutex mutex, if both are held. It is ** OK to get the pLockMutex without holding unixBigLock first, but if ** that happens, the unixBigLock mutex must not be acquired until after ** pLockMutex is released. ** ** OK: enter(unixBigLock), enter(pLockInfo) ** OK: enter(unixBigLock) ** OK: enter(pLockInfo) ** ERROR: enter(pLockInfo), enter(unixBigLock) */ static sqlite3_mutex *unixBigLock = 0; static void unixEnterMutex(void){ assert( sqlite3_mutex_notheld(unixBigLock) ); /* Not a recursive mutex */ sqlite3_mutex_enter(unixBigLock); } static void unixLeaveMutex(void){ assert( sqlite3_mutex_held(unixBigLock) ); sqlite3_mutex_leave(unixBigLock); } #ifdef SQLITE_DEBUG static int unixMutexHeld(void) { return sqlite3_mutex_held(unixBigLock); } #endif #ifdef SQLITE_HAVE_OS_TRACE /* ** Helper function for printing out trace information from debugging ** binaries. This returns the string representation of the supplied ** integer lock-type. */ static const char *azFileLock(int eFileLock){ switch( eFileLock ){ case NO_LOCK: return "NONE"; case SHARED_LOCK: return "SHARED"; case RESERVED_LOCK: return "RESERVED"; case PENDING_LOCK: return "PENDING"; case EXCLUSIVE_LOCK: return "EXCLUSIVE"; } return "ERROR"; } #endif #ifdef SQLITE_LOCK_TRACE /* ** Print out information about all locking operations. ** ** This routine is used for troubleshooting locks on multithreaded ** platforms. Enable by compiling with the -DSQLITE_LOCK_TRACE ** command-line option on the compiler. This code is normally ** turned off. */ static int lockTrace(int fd, int op, struct flock *p){ char *zOpName, *zType; int s; int savedErrno; if( op==F_GETLK ){ zOpName = "GETLK"; }else if( op==F_SETLK ){ zOpName = "SETLK"; }else{ s = osFcntl(fd, op, p); sqlite3DebugPrintf("fcntl unknown %d %d %d\n", fd, op, s); return s; } if( p->l_type==F_RDLCK ){ zType = "RDLCK"; }else if( p->l_type==F_WRLCK ){ zType = "WRLCK"; }else if( p->l_type==F_UNLCK ){ zType = "UNLCK"; }else{ assert( 0 ); } assert( p->l_whence==SEEK_SET ); s = osFcntl(fd, op, p); savedErrno = errno; sqlite3DebugPrintf("fcntl %d %d %s %s %d %d %d %d\n", threadid, fd, zOpName, zType, (int)p->l_start, (int)p->l_len, (int)p->l_pid, s); if( s==(-1) && op==F_SETLK && (p->l_type==F_RDLCK || p->l_type==F_WRLCK) ){ struct flock l2; l2 = *p; osFcntl(fd, F_GETLK, &l2); if( l2.l_type==F_RDLCK ){ zType = "RDLCK"; }else if( l2.l_type==F_WRLCK ){ zType = "WRLCK"; }else if( l2.l_type==F_UNLCK ){ zType = "UNLCK"; }else{ assert( 0 ); } sqlite3DebugPrintf("fcntl-failure-reason: %s %d %d %d\n", zType, (int)l2.l_start, (int)l2.l_len, (int)l2.l_pid); } errno = savedErrno; return s; } #undef osFcntl #define osFcntl lockTrace #endif /* SQLITE_LOCK_TRACE */ /* ** Retry ftruncate() calls that fail due to EINTR ** ** All calls to ftruncate() within this file should be made through ** this wrapper. On the Android platform, bypassing the logic below ** could lead to a corrupt database. */ static int robust_ftruncate(int h, sqlite3_int64 sz){ int rc; #ifdef __ANDROID__ /* On Android, ftruncate() always uses 32-bit offsets, even if ** _FILE_OFFSET_BITS=64 is defined. This means it is unsafe to attempt to ** truncate a file to any size larger than 2GiB. Silently ignore any ** such attempts. */ if( sz>(sqlite3_int64)0x7FFFFFFF ){ rc = SQLITE_OK; }else #endif do{ rc = osFtruncate(h,sz); }while( rc<0 && errno==EINTR ); return rc; } /* ** This routine translates a standard POSIX errno code into something ** useful to the clients of the sqlite3 functions. Specifically, it is ** intended to translate a variety of "try again" errors into SQLITE_BUSY ** and a variety of "please close the file descriptor NOW" errors into ** SQLITE_IOERR ** ** Errors during initialization of locks, or file system support for locks, ** should handle ENOLCK, ENOTSUP, EOPNOTSUPP separately. */ static int sqliteErrorFromPosixError(int posixError, int sqliteIOErr) { assert( (sqliteIOErr == SQLITE_IOERR_LOCK) || (sqliteIOErr == SQLITE_IOERR_UNLOCK) || (sqliteIOErr == SQLITE_IOERR_RDLOCK) || (sqliteIOErr == SQLITE_IOERR_CHECKRESERVEDLOCK) ); switch (posixError) { case EACCES: case EAGAIN: case ETIMEDOUT: case EBUSY: case EINTR: case ENOLCK: /* random NFS retry error, unless during file system support * introspection, in which it actually means what it says */ return SQLITE_BUSY; case EPERM: return SQLITE_PERM; default: return sqliteIOErr; } } /****************************************************************************** ****************** Begin Unique File ID Utility Used By VxWorks *************** ** ** On most versions of unix, we can get a unique ID for a file by concatenating ** the device number and the inode number. But this does not work on VxWorks. ** On VxWorks, a unique file id must be based on the canonical filename. ** ** A pointer to an instance of the following structure can be used as a ** unique file ID in VxWorks. Each instance of this structure contains ** a copy of the canonical filename. There is also a reference count. ** The structure is reclaimed when the number of pointers to it drops to ** zero. ** ** There are never very many files open at one time and lookups are not ** a performance-critical path, so it is sufficient to put these ** structures on a linked list. */ struct vxworksFileId { struct vxworksFileId *pNext; /* Next in a list of them all */ int nRef; /* Number of references to this one */ int nName; /* Length of the zCanonicalName[] string */ char *zCanonicalName; /* Canonical filename */ }; #if OS_VXWORKS /* ** All unique filenames are held on a linked list headed by this ** variable: */ static struct vxworksFileId *vxworksFileList = 0; static sqlite3_mutex *vxworksMutex = 0; /* ** Simplify a filename into its canonical form ** by making the following changes: ** ** * removing any trailing and duplicate / ** * convert /./ into just / ** * convert /A/../ where A is any simple name into just / ** ** Changes are made in-place. Return the new name length. ** ** The original filename is in z[0..n-1]. Return the number of ** characters in the simplified name. */ static int vxworksSimplifyName(char *z, int n){ int i, j; while( n>1 && z[n-1]=='/' ){ n--; } for(i=j=0; i<n; i++){ if( z[i]=='/' ){ if( z[i+1]=='/' ) continue; if( z[i+1]=='.' && i+2<n && z[i+2]=='/' ){ i += 1; continue; } if( z[i+1]=='.' && i+3<n && z[i+2]=='.' && z[i+3]=='/' ){ while( j>0 && z[j-1]!='/' ){ j--; } if( j>0 ){ j--; } i += 2; continue; } } z[j++] = z[i]; } z[j] = 0; return j; } /* ** Find a unique file ID for the given absolute pathname. Return ** a pointer to the vxworksFileId object. This pointer is the unique ** file ID. ** ** The nRef field of the vxworksFileId object is incremented before ** the object is returned. A new vxworksFileId object is created ** and added to the global list if necessary. ** ** If a memory allocation error occurs, return NULL. */ static struct vxworksFileId *vxworksFindFileId(const char *zAbsoluteName){ struct vxworksFileId *pNew; /* search key and new file ID */ struct vxworksFileId *pCandidate; /* For looping over existing file IDs */ int n; /* Length of zAbsoluteName string */ assert( zAbsoluteName[0]=='/' ); n = (int)strlen(zAbsoluteName); pNew = sqlite3_malloc64( sizeof(*pNew) + (n+1) ); if( pNew==0 ) return 0; pNew->zCanonicalName = (char*)&pNew[1]; memcpy(pNew->zCanonicalName, zAbsoluteName, n+1); n = vxworksSimplifyName(pNew->zCanonicalName, n); /* Search for an existing entry that matching the canonical name. ** If found, increment the reference count and return a pointer to ** the existing file ID. */ sqlite3_mutex_enter(vxworksMutex); for(pCandidate=vxworksFileList; pCandidate; pCandidate=pCandidate->pNext){ if( pCandidate->nName==n && memcmp(pCandidate->zCanonicalName, pNew->zCanonicalName, n)==0 ){ sqlite3_free(pNew); pCandidate->nRef++; sqlite3_mutex_leave(vxworksMutex); return pCandidate; } } /* No match was found. We will make a new file ID */ pNew->nRef = 1; pNew->nName = n; pNew->pNext = vxworksFileList; vxworksFileList = pNew; sqlite3_mutex_leave(vxworksMutex); return pNew; } /* ** Decrement the reference count on a vxworksFileId object. Free ** the object when the reference count reaches zero. */ static void vxworksReleaseFileId(struct vxworksFileId *pId){ sqlite3_mutex_enter(vxworksMutex); assert( pId->nRef>0 ); pId->nRef--; if( pId->nRef==0 ){ struct vxworksFileId **pp; for(pp=&vxworksFileList; *pp && *pp!=pId; pp = &((*pp)->pNext)){} assert( *pp==pId ); *pp = pId->pNext; sqlite3_free(pId); } sqlite3_mutex_leave(vxworksMutex); } #endif /* OS_VXWORKS */ /*************** End of Unique File ID Utility Used By VxWorks **************** ******************************************************************************/ /****************************************************************************** *************************** Posix Advisory Locking **************************** ** ** POSIX advisory locks are broken by design. ANSI STD 1003.1 (1996) ** section 6.5.2.2 lines 483 through 490 specify that when a process ** sets or clears a lock, that operation overrides any prior locks set ** by the same process. It does not explicitly say so, but this implies ** that it overrides locks set by the same process using a different ** file descriptor. Consider this test case: ** ** int fd1 = open("./file1", O_RDWR|O_CREAT, 0644); ** int fd2 = open("./file2", O_RDWR|O_CREAT, 0644); ** ** Suppose ./file1 and ./file2 are really the same file (because ** one is a hard or symbolic link to the other) then if you set ** an exclusive lock on fd1, then try to get an exclusive lock ** on fd2, it works. I would have expected the second lock to ** fail since there was already a lock on the file due to fd1. ** But not so. Since both locks came from the same process, the ** second overrides the first, even though they were on different ** file descriptors opened on different file names. ** ** This means that we cannot use POSIX locks to synchronize file access ** among competing threads of the same process. POSIX locks will work fine ** to synchronize access for threads in separate processes, but not ** threads within the same process. ** ** To work around the problem, SQLite has to manage file locks internally ** on its own. Whenever a new database is opened, we have to find the ** specific inode of the database file (the inode is determined by the ** st_dev and st_ino fields of the stat structure that fstat() fills in) ** and check for locks already existing on that inode. When locks are ** created or removed, we have to look at our own internal record of the ** locks to see if another thread has previously set a lock on that same ** inode. ** ** (Aside: The use of inode numbers as unique IDs does not work on VxWorks. ** For VxWorks, we have to use the alternative unique ID system based on ** canonical filename and implemented in the previous division.) ** ** The sqlite3_file structure for POSIX is no longer just an integer file ** descriptor. It is now a structure that holds the integer file ** descriptor and a pointer to a structure that describes the internal ** locks on the corresponding inode. There is one locking structure ** per inode, so if the same inode is opened twice, both unixFile structures ** point to the same locking structure. The locking structure keeps ** a reference count (so we will know when to delete it) and a "cnt" ** field that tells us its internal lock status. cnt==0 means the ** file is unlocked. cnt==-1 means the file has an exclusive lock. ** cnt>0 means there are cnt shared locks on the file. ** ** Any attempt to lock or unlock a file first checks the locking ** structure. The fcntl() system call is only invoked to set a ** POSIX lock if the internal lock structure transitions between ** a locked and an unlocked state. ** ** But wait: there are yet more problems with POSIX advisory locks. ** ** If you close a file descriptor that points to a file that has locks, ** all locks on that file that are owned by the current process are ** released. To work around this problem, each unixInodeInfo object ** maintains a count of the number of pending locks on the inode. ** When an attempt is made to close an unixFile, if there are ** other unixFile open on the same inode that are holding locks, the call ** to close() the file descriptor is deferred until all of the locks clear. ** The unixInodeInfo structure keeps a list of file descriptors that need to ** be closed and that list is walked (and cleared) when the last lock ** clears. ** ** Yet another problem: LinuxThreads do not play well with posix locks. ** ** Many older versions of linux use the LinuxThreads library which is ** not posix compliant. Under LinuxThreads, a lock created by thread ** A cannot be modified or overridden by a different thread B. ** Only thread A can modify the lock. Locking behavior is correct ** if the application uses the newer Native Posix Thread Library (NPTL) ** on linux - with NPTL a lock created by thread A can override locks ** in thread B. But there is no way to know at compile-time which ** threading library is being used. So there is no way to know at ** compile-time whether or not thread A can override locks on thread B. ** One has to do a run-time check to discover the behavior of the ** current process. ** ** SQLite used to support LinuxThreads. But support for LinuxThreads ** was dropped beginning with version 3.7.0. SQLite will still work with ** LinuxThreads provided that (1) there is no more than one connection ** per database file in the same process and (2) database connections ** do not move across threads. */ /* ** An instance of the following structure serves as the key used ** to locate a particular unixInodeInfo object. */ struct unixFileId { dev_t dev; /* Device number */ #if OS_VXWORKS struct vxworksFileId *pId; /* Unique file ID for vxworks. */ #else /* We are told that some versions of Android contain a bug that ** sizes ino_t at only 32-bits instead of 64-bits. (See ** https://android-review.googlesource.com/#/c/115351/3/dist/sqlite3.c) ** To work around this, always allocate 64-bits for the inode number. ** On small machines that only have 32-bit inodes, this wastes 4 bytes, ** but that should not be a big deal. */ /* WAS: ino_t ino; */ u64 ino; /* Inode number */ #endif }; /* ** An instance of the following structure is allocated for each open ** inode. ** ** A single inode can have multiple file descriptors, so each unixFile ** structure contains a pointer to an instance of this object and this ** object keeps a count of the number of unixFile pointing to it. ** ** Mutex rules: ** ** (1) Only the pLockMutex mutex must be held in order to read or write ** any of the locking fields: ** nShared, nLock, eFileLock, bProcessLock, pUnused ** ** (2) When nRef>0, then the following fields are unchanging and can ** be read (but not written) without holding any mutex: ** fileId, pLockMutex ** ** (3) With the exceptions above, all the fields may only be read ** or written while holding the global unixBigLock mutex. ** ** Deadlock prevention: The global unixBigLock mutex may not ** be acquired while holding the pLockMutex mutex. If both unixBigLock ** and pLockMutex are needed, then unixBigLock must be acquired first. */ struct unixInodeInfo { struct unixFileId fileId; /* The lookup key */ sqlite3_mutex *pLockMutex; /* Hold this mutex for... */ int nShared; /* Number of SHARED locks held */ int nLock; /* Number of outstanding file locks */ unsigned char eFileLock; /* One of SHARED_LOCK, RESERVED_LOCK etc. */ unsigned char bProcessLock; /* An exclusive process lock is held */ UnixUnusedFd *pUnused; /* Unused file descriptors to close */ int nRef; /* Number of pointers to this structure */ unixShmNode *pShmNode; /* Shared memory associated with this inode */ unixInodeInfo *pNext; /* List of all unixInodeInfo objects */ unixInodeInfo *pPrev; /* .... doubly linked */ #if SQLITE_ENABLE_LOCKING_STYLE unsigned long long sharedByte; /* for AFP simulated shared lock */ #endif #if OS_VXWORKS sem_t *pSem; /* Named POSIX semaphore */ char aSemName[MAX_PATHNAME+2]; /* Name of that semaphore */ #endif }; /* ** A lists of all unixInodeInfo objects. ** ** Must hold unixBigLock in order to read or write this variable. */ static unixInodeInfo *inodeList = 0; /* All unixInodeInfo objects */ #ifdef SQLITE_DEBUG /* ** True if the inode mutex (on the unixFile.pFileMutex field) is held, or not. ** This routine is used only within assert() to help verify correct mutex ** usage. */ int unixFileMutexHeld(unixFile *pFile){ assert( pFile->pInode ); return sqlite3_mutex_held(pFile->pInode->pLockMutex); } int unixFileMutexNotheld(unixFile *pFile){ assert( pFile->pInode ); return sqlite3_mutex_notheld(pFile->pInode->pLockMutex); } #endif /* ** ** This function - unixLogErrorAtLine(), is only ever called via the macro ** unixLogError(). ** ** It is invoked after an error occurs in an OS function and errno has been ** set. It logs a message using sqlite3_log() containing the current value of ** errno and, if possible, the human-readable equivalent from strerror() or ** strerror_r(). ** ** The first argument passed to the macro should be the error code that ** will be returned to SQLite (e.g. SQLITE_IOERR_DELETE, SQLITE_CANTOPEN). ** The two subsequent arguments should be the name of the OS function that ** failed (e.g. "unlink", "open") and the associated file-system path, ** if any. */ #define unixLogError(a,b,c) unixLogErrorAtLine(a,b,c,__LINE__) static int unixLogErrorAtLine( int errcode, /* SQLite error code */ const char *zFunc, /* Name of OS function that failed */ const char *zPath, /* File path associated with error */ int iLine /* Source line number where error occurred */ ){ char *zErr; /* Message from strerror() or equivalent */ int iErrno = errno; /* Saved syscall error number */ /* If this is not a threadsafe build (SQLITE_THREADSAFE==0), then use ** the strerror() function to obtain the human-readable error message ** equivalent to errno. Otherwise, use strerror_r(). */ #if SQLITE_THREADSAFE && defined(HAVE_STRERROR_R) char aErr[80]; memset(aErr, 0, sizeof(aErr)); zErr = aErr; /* If STRERROR_R_CHAR_P (set by autoconf scripts) or __USE_GNU is defined, ** assume that the system provides the GNU version of strerror_r() that ** returns a pointer to a buffer containing the error message. That pointer ** may point to aErr[], or it may point to some static storage somewhere. ** Otherwise, assume that the system provides the POSIX version of ** strerror_r(), which always writes an error message into aErr[]. ** ** If the code incorrectly assumes that it is the POSIX version that is ** available, the error message will often be an empty string. Not a ** huge problem. Incorrectly concluding that the GNU version is available ** could lead to a segfault though. ** ** Forum post 3f13857fa4062301 reports that the Android SDK may use ** int-type return, depending on its version. */ #if (defined(STRERROR_R_CHAR_P) || defined(__USE_GNU)) \ && !defined(ANDROID) && !defined(__ANDROID__) zErr = # endif strerror_r(iErrno, aErr, sizeof(aErr)-1); #elif SQLITE_THREADSAFE /* This is a threadsafe build, but strerror_r() is not available. */ zErr = ""; #else /* Non-threadsafe build, use strerror(). */ zErr = strerror(iErrno); #endif if( zPath==0 ) zPath = ""; sqlite3_log(errcode, "os_unix.c:%d: (%d) %s(%s) - %s", iLine, iErrno, zFunc, zPath, zErr ); return errcode; } /* ** Close a file descriptor. ** ** We assume that close() almost always works, since it is only in a ** very sick application or on a very sick platform that it might fail. ** If it does fail, simply leak the file descriptor, but do log the ** error. ** ** Note that it is not safe to retry close() after EINTR since the ** file descriptor might have already been reused by another thread. ** So we don't even try to recover from an EINTR. Just log the error ** and move on. */ static void robust_close(unixFile *pFile, int h, int lineno){ if( osClose(h) ){ unixLogErrorAtLine(SQLITE_IOERR_CLOSE, "close", pFile ? pFile->zPath : 0, lineno); } } /* ** Set the pFile->lastErrno. Do this in a subroutine as that provides ** a convenient place to set a breakpoint. */ static void storeLastErrno(unixFile *pFile, int error){ pFile->lastErrno = error; } /* ** Close all file descriptors accumulated in the unixInodeInfo->pUnused list. */ static void closePendingFds(unixFile *pFile){ unixInodeInfo *pInode = pFile->pInode; UnixUnusedFd *p; UnixUnusedFd *pNext; assert( unixFileMutexHeld(pFile) ); for(p=pInode->pUnused; p; p=pNext){ pNext = p->pNext; robust_close(pFile, p->fd, __LINE__); sqlite3_free(p); } pInode->pUnused = 0; } /* ** Release a unixInodeInfo structure previously allocated by findInodeInfo(). ** ** The global mutex must be held when this routine is called, but the mutex ** on the inode being deleted must NOT be held. */ static void releaseInodeInfo(unixFile *pFile){ unixInodeInfo *pInode = pFile->pInode; assert( unixMutexHeld() ); assert( unixFileMutexNotheld(pFile) ); if( ALWAYS(pInode) ){ pInode->nRef--; if( pInode->nRef==0 ){ assert( pInode->pShmNode==0 ); sqlite3_mutex_enter(pInode->pLockMutex); closePendingFds(pFile); sqlite3_mutex_leave(pInode->pLockMutex); if( pInode->pPrev ){ assert( pInode->pPrev->pNext==pInode ); pInode->pPrev->pNext = pInode->pNext; }else{ assert( inodeList==pInode ); inodeList = pInode->pNext; } if( pInode->pNext ){ assert( pInode->pNext->pPrev==pInode ); pInode->pNext->pPrev = pInode->pPrev; } sqlite3_mutex_free(pInode->pLockMutex); sqlite3_free(pInode); } } } /* ** Given a file descriptor, locate the unixInodeInfo object that ** describes that file descriptor. Create a new one if necessary. The ** return value might be uninitialized if an error occurs. ** ** The global mutex must held when calling this routine. ** ** Return an appropriate error code. */ static int findInodeInfo( unixFile *pFile, /* Unix file with file desc used in the key */ unixInodeInfo **ppInode /* Return the unixInodeInfo object here */ ){ int rc; /* System call return code */ int fd; /* The file descriptor for pFile */ struct unixFileId fileId; /* Lookup key for the unixInodeInfo */ struct stat statbuf; /* Low-level file information */ unixInodeInfo *pInode = 0; /* Candidate unixInodeInfo object */ assert( unixMutexHeld() ); /* Get low-level information about the file that we can used to ** create a unique name for the file. */ fd = pFile->h; rc = osFstat(fd, &statbuf); if( rc!=0 ){ storeLastErrno(pFile, errno); #if defined(EOVERFLOW) && defined(SQLITE_DISABLE_LFS) if( pFile->lastErrno==EOVERFLOW ) return SQLITE_NOLFS; #endif return SQLITE_IOERR; } #ifdef __APPLE__ /* On OS X on an msdos filesystem, the inode number is reported ** incorrectly for zero-size files. See ticket #3260. To work ** around this problem (we consider it a bug in OS X, not SQLite) ** we always increase the file size to 1 by writing a single byte ** prior to accessing the inode number. The one byte written is ** an ASCII 'S' character which also happens to be the first byte ** in the header of every SQLite database. In this way, if there ** is a race condition such that another thread has already populated ** the first page of the database, no damage is done. */ if( statbuf.st_size==0 && (pFile->fsFlags & SQLITE_FSFLAGS_IS_MSDOS)!=0 ){ do{ rc = osWrite(fd, "S", 1); }while( rc<0 && errno==EINTR ); if( rc!=1 ){ storeLastErrno(pFile, errno); return SQLITE_IOERR; } if( fsync(fd) ){ storeLastErrno(pFile, errno); return SQLITE_IOERR_FSYNC; } rc = osFstat(fd, &statbuf); if( rc!=0 ){ storeLastErrno(pFile, errno); return SQLITE_IOERR; } } #endif memset(&fileId, 0, sizeof(fileId)); fileId.dev = statbuf.st_dev; #if OS_VXWORKS fileId.pId = pFile->pId; #else fileId.ino = (u64)statbuf.st_ino; #endif assert( unixMutexHeld() ); pInode = inodeList; while( pInode && memcmp(&fileId, &pInode->fileId, sizeof(fileId)) ){ pInode = pInode->pNext; } if( pInode==0 ){ pInode = sqlite3_malloc64( sizeof(*pInode) ); if( pInode==0 ){ return SQLITE_NOMEM_BKPT; } memset(pInode, 0, sizeof(*pInode)); memcpy(&pInode->fileId, &fileId, sizeof(fileId)); if( sqlite3GlobalConfig.bCoreMutex ){ pInode->pLockMutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST); if( pInode->pLockMutex==0 ){ sqlite3_free(pInode); return SQLITE_NOMEM_BKPT; } } pInode->nRef = 1; assert( unixMutexHeld() ); pInode->pNext = inodeList; pInode->pPrev = 0; if( inodeList ) inodeList->pPrev = pInode; inodeList = pInode; }else{ pInode->nRef++; } *ppInode = pInode; return SQLITE_OK; } /* ** Return TRUE if pFile has been renamed or unlinked since it was first opened. */ static int fileHasMoved(unixFile *pFile){ #if OS_VXWORKS return pFile->pInode!=0 && pFile->pId!=pFile->pInode->fileId.pId; #else struct stat buf; return pFile->pInode!=0 && (osStat(pFile->zPath, &buf)!=0 || (u64)buf.st_ino!=pFile->pInode->fileId.ino); #endif } /* ** Check a unixFile that is a database. Verify the following: ** ** (1) There is exactly one hard link on the file ** (2) The file is not a symbolic link ** (3) The file has not been renamed or unlinked ** ** Issue sqlite3_log(SQLITE_WARNING,...) messages if anything is not right. */ static void verifyDbFile(unixFile *pFile){ struct stat buf; int rc; /* These verifications occurs for the main database only */ if( pFile->ctrlFlags & UNIXFILE_NOLOCK ) return; rc = osFstat(pFile->h, &buf); if( rc!=0 ){ sqlite3_log(SQLITE_WARNING, "cannot fstat db file %s", pFile->zPath); return; } if( buf.st_nlink==0 ){ sqlite3_log(SQLITE_WARNING, "file unlinked while open: %s", pFile->zPath); return; } if( buf.st_nlink>1 ){ sqlite3_log(SQLITE_WARNING, "multiple links to file: %s", pFile->zPath); return; } if( fileHasMoved(pFile) ){ sqlite3_log(SQLITE_WARNING, "file renamed while open: %s", pFile->zPath); return; } } /* ** This routine checks if there is a RESERVED lock held on the specified ** file by this or any other process. If such a lock is held, set *pResOut ** to a non-zero value otherwise *pResOut is set to zero. The return value ** is set to SQLITE_OK unless an I/O error occurs during lock checking. */ static int unixCheckReservedLock(sqlite3_file *id, int *pResOut){ int rc = SQLITE_OK; int reserved = 0; unixFile *pFile = (unixFile*)id; SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; ); assert( pFile ); assert( pFile->eFileLock<=SHARED_LOCK ); sqlite3_mutex_enter(pFile->pInode->pLockMutex); /* Check if a thread in this process holds such a lock */ if( pFile->pInode->eFileLock>SHARED_LOCK ){ reserved = 1; } /* Otherwise see if some other process holds it. */ #ifndef __DJGPP__ if( !reserved && !pFile->pInode->bProcessLock ){ struct flock lock; lock.l_whence = SEEK_SET; lock.l_start = RESERVED_BYTE; lock.l_len = 1; lock.l_type = F_WRLCK; if( osFcntl(pFile->h, F_GETLK, &lock) ){ rc = SQLITE_IOERR_CHECKRESERVEDLOCK; storeLastErrno(pFile, errno); } else if( lock.l_type!=F_UNLCK ){ reserved = 1; } } #endif sqlite3_mutex_leave(pFile->pInode->pLockMutex); OSTRACE(("TEST WR-LOCK %d %d %d (unix)\n", pFile->h, rc, reserved)); *pResOut = reserved; return rc; } /* Forward declaration*/ static int unixSleep(sqlite3_vfs*,int); /* ** Set a posix-advisory-lock. ** ** There are two versions of this routine. If compiled with ** SQLITE_ENABLE_SETLK_TIMEOUT then the routine has an extra parameter ** which is a pointer to a unixFile. If the unixFile->iBusyTimeout ** value is set, then it is the number of milliseconds to wait before ** failing the lock. The iBusyTimeout value is always reset back to ** zero on each call. ** ** If SQLITE_ENABLE_SETLK_TIMEOUT is not defined, then do a non-blocking ** attempt to set the lock. */ #ifndef SQLITE_ENABLE_SETLK_TIMEOUT # define osSetPosixAdvisoryLock(h,x,t) osFcntl(h,F_SETLK,x) #else static int osSetPosixAdvisoryLock( int h, /* The file descriptor on which to take the lock */ struct flock *pLock, /* The description of the lock */ unixFile *pFile /* Structure holding timeout value */ ){ int rc = 0; if( pFile->iBusyTimeout==0 ){ /* unixFile->iBusyTimeout is set to 0. In this case, attempt a ** non-blocking lock. */ rc = osFcntl(h,F_SETLK,pLock); }else{ /* unixFile->iBusyTimeout is set to greater than zero. In this case, ** attempt a blocking-lock with a unixFile->iBusyTimeout ms timeout. ** ** On systems that support some kind of blocking file lock operation, ** this block should be replaced by code to attempt a blocking lock ** with a timeout of unixFile->iBusyTimeout ms. The code below is ** placeholder code. If SQLITE_TEST is defined, the placeholder code ** retries the lock once every 1ms until it succeeds or the timeout ** is reached. Or, if SQLITE_TEST is not defined, the placeholder ** code attempts a non-blocking lock and sets unixFile->iBusyTimeout ** to 0. This causes the caller to return SQLITE_BUSY, instead of ** SQLITE_BUSY_TIMEOUT to SQLite - as required by a VFS that does not ** support blocking locks. */ #ifdef SQLITE_TEST int tm = pFile->iBusyTimeout; while( tm>0 ){ rc = osFcntl(h,F_SETLK,pLock); if( rc==0 ) break; unixSleep(0,1000); tm--; } #else rc = osFcntl(h,F_SETLK,pLock); pFile->iBusyTimeout = 0; #endif /* End of code to replace with real blocking-locks code. */ } return rc; } #endif /* SQLITE_ENABLE_SETLK_TIMEOUT */ /* ** Attempt to set a system-lock on the file pFile. The lock is ** described by pLock. ** ** If the pFile was opened read/write from unix-excl, then the only lock ** ever obtained is an exclusive lock, and it is obtained exactly once ** the first time any lock is attempted. All subsequent system locking ** operations become no-ops. Locking operations still happen internally, ** in order to coordinate access between separate database connections ** within this process, but all of that is handled in memory and the ** operating system does not participate. ** ** This function is a pass-through to fcntl(F_SETLK) if pFile is using ** any VFS other than "unix-excl" or if pFile is opened on "unix-excl" ** and is read-only. ** ** Zero is returned if the call completes successfully, or -1 if a call ** to fcntl() fails. In this case, errno is set appropriately (by fcntl()). */ static int unixFileLock(unixFile *pFile, struct flock *pLock){ int rc; unixInodeInfo *pInode = pFile->pInode; assert( pInode!=0 ); assert( sqlite3_mutex_held(pInode->pLockMutex) ); if( (pFile->ctrlFlags & (UNIXFILE_EXCL|UNIXFILE_RDONLY))==UNIXFILE_EXCL ){ if( pInode->bProcessLock==0 ){ struct flock lock; /* assert( pInode->nLock==0 ); <-- Not true if unix-excl READONLY used */ lock.l_whence = SEEK_SET; lock.l_start = SHARED_FIRST; lock.l_len = SHARED_SIZE; lock.l_type = F_WRLCK; rc = osSetPosixAdvisoryLock(pFile->h, &lock, pFile); if( rc<0 ) return rc; pInode->bProcessLock = 1; pInode->nLock++; }else{ rc = 0; } }else{ #ifdef SQLITE_ENABLE_SETLK_TIMEOUT if( pFile->bBlockOnConnect && pLock->l_type==F_RDLCK && pLock->l_start==SHARED_FIRST && pLock->l_len==SHARED_SIZE ){ rc = osFcntl(pFile->h, F_SETLKW, pLock); }else #endif rc = osSetPosixAdvisoryLock(pFile->h, pLock, pFile); } return rc; } #if !defined(SQLITE_WASI) && !defined(SQLITE_OMIT_WAL) /* Forward reference */ static int unixIsSharingShmNode(unixFile*); #else #define unixIsSharingShmNode(pFile) (0) #endif /* ** Lock the file with the lock specified by parameter eFileLock - one ** of the following: ** ** (1) SHARED_LOCK ** (2) RESERVED_LOCK ** (3) PENDING_LOCK ** (4) EXCLUSIVE_LOCK ** ** Sometimes when requesting one lock state, additional lock states ** are inserted in between. The locking might fail on one of the later ** transitions leaving the lock state different from what it started but ** still short of its goal. The following chart shows the allowed ** transitions and the inserted intermediate states: ** ** UNLOCKED -> SHARED ** SHARED -> RESERVED ** SHARED -> EXCLUSIVE ** RESERVED -> (PENDING) -> EXCLUSIVE ** PENDING -> EXCLUSIVE ** ** This routine will only increase a lock. Use the sqlite3OsUnlock() ** routine to lower a locking level. */ static int unixLock(sqlite3_file *id, int eFileLock){ /* The following describes the implementation of the various locks and ** lock transitions in terms of the POSIX advisory shared and exclusive ** lock primitives (called read-locks and write-locks below, to avoid ** confusion with SQLite lock names). The algorithms are complicated ** slightly in order to be compatible with Windows95 systems simultaneously ** accessing the same database file, in case that is ever required. ** ** Symbols defined in os.h identify the 'pending byte' and the 'reserved ** byte', each single bytes at well known offsets, and the 'shared byte ** range', a range of 510 bytes at a well known offset. ** ** To obtain a SHARED lock, a read-lock is obtained on the 'pending ** byte'. If this is successful, 'shared byte range' is read-locked ** and the lock on the 'pending byte' released. (Legacy note: When ** SQLite was first developed, Windows95 systems were still very common, ** and Windows95 lacks a shared-lock capability. So on Windows95, a ** single randomly selected by from the 'shared byte range' is locked. ** Windows95 is now pretty much extinct, but this work-around for the ** lack of shared-locks on Windows95 lives on, for backwards ** compatibility.) ** ** A process may only obtain a RESERVED lock after it has a SHARED lock. ** A RESERVED lock is implemented by grabbing a write-lock on the ** 'reserved byte'. ** ** An EXCLUSIVE lock may only be requested after either a SHARED or ** RESERVED lock is held. An EXCLUSIVE lock is implemented by obtaining ** a write-lock on the entire 'shared byte range'. Since all other locks ** require a read-lock on one of the bytes within this range, this ensures ** that no other locks are held on the database. ** ** If a process that holds a RESERVED lock requests an EXCLUSIVE, then ** a PENDING lock is obtained first. A PENDING lock is implemented by ** obtaining a write-lock on the 'pending byte'. This ensures that no new ** SHARED locks can be obtained, but existing SHARED locks are allowed to ** persist. If the call to this function fails to obtain the EXCLUSIVE ** lock in this case, it holds the PENDING lock instead. The client may ** then re-attempt the EXCLUSIVE lock later on, after existing SHARED ** locks have cleared. */ int rc = SQLITE_OK; unixFile *pFile = (unixFile*)id; unixInodeInfo *pInode; struct flock lock; int tErrno = 0; assert( pFile ); OSTRACE(("LOCK %d %s was %s(%s,%d) pid=%d (unix)\n", pFile->h, azFileLock(eFileLock), azFileLock(pFile->eFileLock), azFileLock(pFile->pInode->eFileLock), pFile->pInode->nShared, osGetpid(0))); /* If there is already a lock of this type or more restrictive on the ** unixFile, do nothing. Don't use the end_lock: exit path, as ** unixEnterMutex() hasn't been called yet. */ if( pFile->eFileLock>=eFileLock ){ OSTRACE(("LOCK %d %s ok (already held) (unix)\n", pFile->h, azFileLock(eFileLock))); return SQLITE_OK; } /* Make sure the locking sequence is correct. ** (1) We never move from unlocked to anything higher than shared lock. ** (2) SQLite never explicitly requests a pending lock. ** (3) A shared lock is always held when a reserve lock is requested. */ assert( pFile->eFileLock!=NO_LOCK || eFileLock==SHARED_LOCK ); assert( eFileLock!=PENDING_LOCK ); assert( eFileLock!=RESERVED_LOCK || pFile->eFileLock==SHARED_LOCK ); /* This mutex is needed because pFile->pInode is shared across threads */ pInode = pFile->pInode; sqlite3_mutex_enter(pInode->pLockMutex); /* If some thread using this PID has a lock via a different unixFile* ** handle that precludes the requested lock, return BUSY. */ if( (pFile->eFileLock!=pInode->eFileLock && (pInode->eFileLock>=PENDING_LOCK || eFileLock>SHARED_LOCK)) ){ rc = SQLITE_BUSY; goto end_lock; } /* If a SHARED lock is requested, and some thread using this PID already ** has a SHARED or RESERVED lock, then increment reference counts and ** return SQLITE_OK. */ if( eFileLock==SHARED_LOCK && (pInode->eFileLock==SHARED_LOCK || pInode->eFileLock==RESERVED_LOCK) ){ assert( eFileLock==SHARED_LOCK ); assert( pFile->eFileLock==0 ); assert( pInode->nShared>0 ); pFile->eFileLock = SHARED_LOCK; pInode->nShared++; pInode->nLock++; goto end_lock; } /* A PENDING lock is needed before acquiring a SHARED lock and before ** acquiring an EXCLUSIVE lock. For the SHARED lock, the PENDING will ** be released. */ lock.l_len = 1L; lock.l_whence = SEEK_SET; if( eFileLock==SHARED_LOCK || (eFileLock==EXCLUSIVE_LOCK && pFile->eFileLock==RESERVED_LOCK) ){ lock.l_type = (eFileLock==SHARED_LOCK?F_RDLCK:F_WRLCK); lock.l_start = PENDING_BYTE; if( unixFileLock(pFile, &lock) ){ tErrno = errno; rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK); if( rc!=SQLITE_BUSY ){ storeLastErrno(pFile, tErrno); } goto end_lock; }else if( eFileLock==EXCLUSIVE_LOCK ){ pFile->eFileLock = PENDING_LOCK; pInode->eFileLock = PENDING_LOCK; } } /* If control gets to this point, then actually go ahead and make ** operating system calls for the specified lock. */ if( eFileLock==SHARED_LOCK ){ assert( pInode->nShared==0 ); assert( pInode->eFileLock==0 ); assert( rc==SQLITE_OK ); /* Now get the read-lock */ lock.l_start = SHARED_FIRST; lock.l_len = SHARED_SIZE; if( unixFileLock(pFile, &lock) ){ tErrno = errno; rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK); } /* Drop the temporary PENDING lock */ lock.l_start = PENDING_BYTE; lock.l_len = 1L; lock.l_type = F_UNLCK; if( unixFileLock(pFile, &lock) && rc==SQLITE_OK ){ /* This could happen with a network mount */ tErrno = errno; rc = SQLITE_IOERR_UNLOCK; } if( rc ){ if( rc!=SQLITE_BUSY ){ storeLastErrno(pFile, tErrno); } goto end_lock; }else{ pFile->eFileLock = SHARED_LOCK; pInode->nLock++; pInode->nShared = 1; } }else if( eFileLock==EXCLUSIVE_LOCK && pInode->nShared>1 ){ /* We are trying for an exclusive lock but another thread in this ** same process is still holding a shared lock. */ rc = SQLITE_BUSY; }else if( unixIsSharingShmNode(pFile) ){ /* We are in WAL mode and attempting to delete the SHM and WAL ** files due to closing the connection or changing out of WAL mode, ** but another process still holds locks on the SHM file, thus ** indicating that database locks have been broken, perhaps due ** to a rogue close(open(dbFile)) or similar. */ rc = SQLITE_BUSY; }else{ /* The request was for a RESERVED or EXCLUSIVE lock. It is ** assumed that there is a SHARED or greater lock on the file ** already. */ assert( 0!=pFile->eFileLock ); lock.l_type = F_WRLCK; assert( eFileLock==RESERVED_LOCK || eFileLock==EXCLUSIVE_LOCK ); if( eFileLock==RESERVED_LOCK ){ lock.l_start = RESERVED_BYTE; lock.l_len = 1L; }else{ lock.l_start = SHARED_FIRST; lock.l_len = SHARED_SIZE; } if( unixFileLock(pFile, &lock) ){ tErrno = errno; rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK); if( rc!=SQLITE_BUSY ){ storeLastErrno(pFile, tErrno); } } } #ifdef SQLITE_DEBUG /* Set up the transaction-counter change checking flags when ** transitioning from a SHARED to a RESERVED lock. The change ** from SHARED to RESERVED marks the beginning of a normal ** write operation (not a hot journal rollback). */ if( rc==SQLITE_OK && pFile->eFileLock<=SHARED_LOCK && eFileLock==RESERVED_LOCK ){ pFile->transCntrChng = 0; pFile->dbUpdate = 0; pFile->inNormalWrite = 1; } #endif if( rc==SQLITE_OK ){ pFile->eFileLock = eFileLock; pInode->eFileLock = eFileLock; } end_lock: sqlite3_mutex_leave(pInode->pLockMutex); OSTRACE(("LOCK %d %s %s (unix)\n", pFile->h, azFileLock(eFileLock), rc==SQLITE_OK ? "ok" : "failed")); return rc; } /* ** Add the file descriptor used by file handle pFile to the corresponding ** pUnused list. */ static void setPendingFd(unixFile *pFile){ unixInodeInfo *pInode = pFile->pInode; UnixUnusedFd *p = pFile->pPreallocatedUnused; assert( unixFileMutexHeld(pFile) ); p->pNext = pInode->pUnused; pInode->pUnused = p; pFile->h = -1; pFile->pPreallocatedUnused = 0; } /* ** Lower the locking level on file descriptor pFile to eFileLock. eFileLock ** must be either NO_LOCK or SHARED_LOCK. ** ** If the locking level of the file descriptor is already at or below ** the requested locking level, this routine is a no-op. ** ** If handleNFSUnlock is true, then on downgrading an EXCLUSIVE_LOCK to SHARED ** the byte range is divided into 2 parts and the first part is unlocked then ** set to a read lock, then the other part is simply unlocked. This works ** around a bug in BSD NFS lockd (also seen on MacOSX 10.3+) that fails to ** remove the write lock on a region when a read lock is set. */ static int posixUnlock(sqlite3_file *id, int eFileLock, int handleNFSUnlock){ unixFile *pFile = (unixFile*)id; unixInodeInfo *pInode; struct flock lock; int rc = SQLITE_OK; assert( pFile ); OSTRACE(("UNLOCK %d %d was %d(%d,%d) pid=%d (unix)\n", pFile->h, eFileLock, pFile->eFileLock, pFile->pInode->eFileLock, pFile->pInode->nShared, osGetpid(0))); assert( eFileLock<=SHARED_LOCK ); if( pFile->eFileLock<=eFileLock ){ return SQLITE_OK; } pInode = pFile->pInode; sqlite3_mutex_enter(pInode->pLockMutex); assert( pInode->nShared!=0 ); if( pFile->eFileLock>SHARED_LOCK ){ assert( pInode->eFileLock==pFile->eFileLock ); #ifdef SQLITE_DEBUG /* When reducing a lock such that other processes can start ** reading the database file again, make sure that the ** transaction counter was updated if any part of the database ** file changed. If the transaction counter is not updated, ** other connections to the same file might not realize that ** the file has changed and hence might not know to flush their ** cache. The use of a stale cache can lead to database corruption. */ pFile->inNormalWrite = 0; #endif /* downgrading to a shared lock on NFS involves clearing the write lock ** before establishing the readlock - to avoid a race condition we downgrade ** the lock in 2 blocks, so that part of the range will be covered by a ** write lock until the rest is covered by a read lock: ** 1: [WWWWW] ** 2: [....W] ** 3: [RRRRW] ** 4: [RRRR.] */ if( eFileLock==SHARED_LOCK ){ #if !defined(__APPLE__) || !SQLITE_ENABLE_LOCKING_STYLE (void)handleNFSUnlock; assert( handleNFSUnlock==0 ); #endif #if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE if( handleNFSUnlock ){ int tErrno; /* Error code from system call errors */ off_t divSize = SHARED_SIZE - 1; lock.l_type = F_UNLCK; lock.l_whence = SEEK_SET; lock.l_start = SHARED_FIRST; lock.l_len = divSize; if( unixFileLock(pFile, &lock)==(-1) ){ tErrno = errno; rc = SQLITE_IOERR_UNLOCK; storeLastErrno(pFile, tErrno); goto end_unlock; } lock.l_type = F_RDLCK; lock.l_whence = SEEK_SET; lock.l_start = SHARED_FIRST; lock.l_len = divSize; if( unixFileLock(pFile, &lock)==(-1) ){ tErrno = errno; rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_RDLOCK); if( IS_LOCK_ERROR(rc) ){ storeLastErrno(pFile, tErrno); } goto end_unlock; } lock.l_type = F_UNLCK; lock.l_whence = SEEK_SET; lock.l_start = SHARED_FIRST+divSize; lock.l_len = SHARED_SIZE-divSize; if( unixFileLock(pFile, &lock)==(-1) ){ tErrno = errno; rc = SQLITE_IOERR_UNLOCK; storeLastErrno(pFile, tErrno); goto end_unlock; } }else #endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */ { lock.l_type = F_RDLCK; lock.l_whence = SEEK_SET; lock.l_start = SHARED_FIRST; lock.l_len = SHARED_SIZE; if( unixFileLock(pFile, &lock) ){ /* In theory, the call to unixFileLock() cannot fail because another ** process is holding an incompatible lock. If it does, this ** indicates that the other process is not following the locking ** protocol. If this happens, return SQLITE_IOERR_RDLOCK. Returning ** SQLITE_BUSY would confuse the upper layer (in practice it causes ** an assert to fail). */ rc = SQLITE_IOERR_RDLOCK; storeLastErrno(pFile, errno); goto end_unlock; } } } lock.l_type = F_UNLCK; lock.l_whence = SEEK_SET; lock.l_start = PENDING_BYTE; lock.l_len = 2L; assert( PENDING_BYTE+1==RESERVED_BYTE ); if( unixFileLock(pFile, &lock)==0 ){ pInode->eFileLock = SHARED_LOCK; }else{ rc = SQLITE_IOERR_UNLOCK; storeLastErrno(pFile, errno); goto end_unlock; } } if( eFileLock==NO_LOCK ){ /* Decrement the shared lock counter. Release the lock using an ** OS call only when all threads in this same process have released ** the lock. */ pInode->nShared--; if( pInode->nShared==0 ){ lock.l_type = F_UNLCK; lock.l_whence = SEEK_SET; lock.l_start = lock.l_len = 0L; if( unixFileLock(pFile, &lock)==0 ){ pInode->eFileLock = NO_LOCK; }else{ rc = SQLITE_IOERR_UNLOCK; storeLastErrno(pFile, errno); pInode->eFileLock = NO_LOCK; pFile->eFileLock = NO_LOCK; } } /* Decrement the count of locks against this same file. When the ** count reaches zero, close any other file descriptors whose close ** was deferred because of outstanding locks. */ pInode->nLock--; assert( pInode->nLock>=0 ); if( pInode->nLock==0 ) closePendingFds(pFile); } end_unlock: sqlite3_mutex_leave(pInode->pLockMutex); if( rc==SQLITE_OK ){ pFile->eFileLock = eFileLock; } return rc; } /* ** Lower the locking level on file descriptor pFile to eFileLock. eFileLock ** must be either NO_LOCK or SHARED_LOCK. ** ** If the locking level of the file descriptor is already at or below ** the requested locking level, this routine is a no-op. */ static int unixUnlock(sqlite3_file *id, int eFileLock){ #if SQLITE_MAX_MMAP_SIZE>0 assert( eFileLock==SHARED_LOCK || ((unixFile *)id)->nFetchOut==0 ); #endif return posixUnlock(id, eFileLock, 0); } #if SQLITE_MAX_MMAP_SIZE>0 static int unixMapfile(unixFile *pFd, i64 nByte); static void unixUnmapfile(unixFile *pFd); #endif /* ** This function performs the parts of the "close file" operation ** common to all locking schemes. It closes the directory and file ** handles, if they are valid, and sets all fields of the unixFile ** structure to 0. ** ** It is *not* necessary to hold the mutex when this routine is called, ** even on VxWorks. A mutex will be acquired on VxWorks by the ** vxworksReleaseFileId() routine. */ static int closeUnixFile(sqlite3_file *id){ unixFile *pFile = (unixFile*)id; #if SQLITE_MAX_MMAP_SIZE>0 unixUnmapfile(pFile); #endif if( pFile->h>=0 ){ robust_close(pFile, pFile->h, __LINE__); pFile->h = -1; } #if OS_VXWORKS if( pFile->pId ){ if( pFile->ctrlFlags & UNIXFILE_DELETE ){ osUnlink(pFile->pId->zCanonicalName); } vxworksReleaseFileId(pFile->pId); pFile->pId = 0; } #endif #ifdef SQLITE_UNLINK_AFTER_CLOSE if( pFile->ctrlFlags & UNIXFILE_DELETE ){ osUnlink(pFile->zPath); sqlite3_free(*(char**)&pFile->zPath); pFile->zPath = 0; } #endif OSTRACE(("CLOSE %-3d\n", pFile->h)); OpenCounter(-1); sqlite3_free(pFile->pPreallocatedUnused); memset(pFile, 0, sizeof(unixFile)); return SQLITE_OK; } /* ** Close a file. */ static int unixClose(sqlite3_file *id){ int rc = SQLITE_OK; unixFile *pFile = (unixFile *)id; unixInodeInfo *pInode = pFile->pInode; assert( pInode!=0 ); verifyDbFile(pFile); unixUnlock(id, NO_LOCK); assert( unixFileMutexNotheld(pFile) ); unixEnterMutex(); /* unixFile.pInode is always valid here. Otherwise, a different close ** routine (e.g. nolockClose()) would be called instead. */ assert( pFile->pInode->nLock>0 || pFile->pInode->bProcessLock==0 ); sqlite3_mutex_enter(pInode->pLockMutex); if( pInode->nLock ){ /* If there are outstanding locks, do not actually close the file just ** yet because that would clear those locks. Instead, add the file ** descriptor to pInode->pUnused list. It will be automatically closed ** when the last lock is cleared. */ setPendingFd(pFile); } sqlite3_mutex_leave(pInode->pLockMutex); releaseInodeInfo(pFile); assert( pFile->pShm==0 ); rc = closeUnixFile(id); unixLeaveMutex(); return rc; } /************** End of the posix advisory lock implementation ***************** ******************************************************************************/ /****************************************************************************** ****************************** No-op Locking ********************************** ** ** Of the various locking implementations available, this is by far the ** simplest: locking is ignored. No attempt is made to lock the database ** file for reading or writing. ** ** This locking mode is appropriate for use on read-only databases ** (ex: databases that are burned into CD-ROM, for example.) It can ** also be used if the application employs some external mechanism to ** prevent simultaneous access of the same database by two or more ** database connections. But there is a serious risk of database ** corruption if this locking mode is used in situations where multiple ** database connections are accessing the same database file at the same ** time and one or more of those connections are writing. */ static int nolockCheckReservedLock(sqlite3_file *NotUsed, int *pResOut){ UNUSED_PARAMETER(NotUsed); *pResOut = 0; return SQLITE_OK; } static int nolockLock(sqlite3_file *NotUsed, int NotUsed2){ UNUSED_PARAMETER2(NotUsed, NotUsed2); return SQLITE_OK; } static int nolockUnlock(sqlite3_file *NotUsed, int NotUsed2){ UNUSED_PARAMETER2(NotUsed, NotUsed2); return SQLITE_OK; } /* ** Close the file. */ static int nolockClose(sqlite3_file *id) { return closeUnixFile(id); } /******************* End of the no-op lock implementation ********************* ******************************************************************************/ /****************************************************************************** ************************* Begin dot-file Locking ****************************** ** ** The dotfile locking implementation uses the existence of separate lock ** files (really a directory) to control access to the database. This works ** on just about every filesystem imaginable. But there are serious downsides: ** ** (1) There is zero concurrency. A single reader blocks all other ** connections from reading or writing the database. ** ** (2) An application crash or power loss can leave stale lock files ** sitting around that need to be cleared manually. ** ** Nevertheless, a dotlock is an appropriate locking mode for use if no ** other locking strategy is available. ** ** Dotfile locking works by creating a subdirectory in the same directory as ** the database and with the same name but with a ".lock" extension added. ** The existence of a lock directory implies an EXCLUSIVE lock. All other ** lock types (SHARED, RESERVED, PENDING) are mapped into EXCLUSIVE. */ /* ** The file suffix added to the data base filename in order to create the ** lock directory. */ #define DOTLOCK_SUFFIX ".lock" /* ** This routine checks if there is a RESERVED lock held on the specified ** file by this or any other process. If the caller holds a SHARED ** or greater lock when it is called, then it is assumed that no other ** client may hold RESERVED. Or, if the caller holds no lock, then it ** is assumed another client holds RESERVED if the lock-file exists. */ static int dotlockCheckReservedLock(sqlite3_file *id, int *pResOut) { unixFile *pFile = (unixFile*)id; SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; ); if( pFile->eFileLock>=SHARED_LOCK ){ *pResOut = 0; }else{ *pResOut = osAccess((const char*)pFile->lockingContext, 0)==0; } OSTRACE(("TEST WR-LOCK %d %d %d (dotlock)\n", pFile->h, 0, *pResOut)); return SQLITE_OK; } /* ** Lock the file with the lock specified by parameter eFileLock - one ** of the following: ** ** (1) SHARED_LOCK ** (2) RESERVED_LOCK ** (3) PENDING_LOCK ** (4) EXCLUSIVE_LOCK ** ** Sometimes when requesting one lock state, additional lock states ** are inserted in between. The locking might fail on one of the later ** transitions leaving the lock state different from what it started but ** still short of its goal. The following chart shows the allowed ** transitions and the inserted intermediate states: ** ** UNLOCKED -> SHARED ** SHARED -> RESERVED ** SHARED -> (PENDING) -> EXCLUSIVE ** RESERVED -> (PENDING) -> EXCLUSIVE ** PENDING -> EXCLUSIVE ** ** This routine will only increase a lock. Use the sqlite3OsUnlock() ** routine to lower a locking level. ** ** With dotfile locking, we really only support state (4): EXCLUSIVE. ** But we track the other locking levels internally. */ static int dotlockLock(sqlite3_file *id, int eFileLock) { unixFile *pFile = (unixFile*)id; char *zLockFile = (char *)pFile->lockingContext; int rc = SQLITE_OK; /* If we have any lock, then the lock file already exists. All we have ** to do is adjust our internal record of the lock level. */ if( pFile->eFileLock > NO_LOCK ){ pFile->eFileLock = eFileLock; /* Always update the timestamp on the old file */ #ifdef HAVE_UTIME utime(zLockFile, NULL); #else utimes(zLockFile, NULL); #endif return SQLITE_OK; } /* grab an exclusive lock */ rc = osMkdir(zLockFile, 0777); if( rc<0 ){ /* failed to open/create the lock directory */ int tErrno = errno; if( EEXIST == tErrno ){ rc = SQLITE_BUSY; } else { rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK); if( rc!=SQLITE_BUSY ){ storeLastErrno(pFile, tErrno); } } return rc; } /* got it, set the type and return ok */ pFile->eFileLock = eFileLock; return rc; } /* ** Lower the locking level on file descriptor pFile to eFileLock. eFileLock ** must be either NO_LOCK or SHARED_LOCK. ** ** If the locking level of the file descriptor is already at or below ** the requested locking level, this routine is a no-op. ** ** When the locking level reaches NO_LOCK, delete the lock file. */ static int dotlockUnlock(sqlite3_file *id, int eFileLock) { unixFile *pFile = (unixFile*)id; char *zLockFile = (char *)pFile->lockingContext; int rc; assert( pFile ); OSTRACE(("UNLOCK %d %d was %d pid=%d (dotlock)\n", pFile->h, eFileLock, pFile->eFileLock, osGetpid(0))); assert( eFileLock<=SHARED_LOCK ); /* no-op if possible */ if( pFile->eFileLock==eFileLock ){ return SQLITE_OK; } /* To downgrade to shared, simply update our internal notion of the ** lock state. No need to mess with the file on disk. */ if( eFileLock==SHARED_LOCK ){ pFile->eFileLock = SHARED_LOCK; return SQLITE_OK; } /* To fully unlock the database, delete the lock file */ assert( eFileLock==NO_LOCK ); rc = osRmdir(zLockFile); if( rc<0 ){ int tErrno = errno; if( tErrno==ENOENT ){ rc = SQLITE_OK; }else{ rc = SQLITE_IOERR_UNLOCK; storeLastErrno(pFile, tErrno); } return rc; } pFile->eFileLock = NO_LOCK; return SQLITE_OK; } /* ** Close a file. Make sure the lock has been released before closing. */ static int dotlockClose(sqlite3_file *id) { unixFile *pFile = (unixFile*)id; assert( id!=0 ); dotlockUnlock(id, NO_LOCK); sqlite3_free(pFile->lockingContext); return closeUnixFile(id); } /****************** End of the dot-file lock implementation ******************* ******************************************************************************/ /****************************************************************************** ************************** Begin flock Locking ******************************** ** ** Use the flock() system call to do file locking. ** ** flock() locking is like dot-file locking in that the various ** fine-grain locking levels supported by SQLite are collapsed into ** a single exclusive lock. In other words, SHARED, RESERVED, and ** PENDING locks are the same thing as an EXCLUSIVE lock. SQLite ** still works when you do this, but concurrency is reduced since ** only a single process can be reading the database at a time. ** ** Omit this section if SQLITE_ENABLE_LOCKING_STYLE is turned off */ #if SQLITE_ENABLE_LOCKING_STYLE /* ** Retry flock() calls that fail with EINTR */ #ifdef EINTR static int robust_flock(int fd, int op){ int rc; do{ rc = flock(fd,op); }while( rc<0 && errno==EINTR ); return rc; } #else # define robust_flock(a,b) flock(a,b) #endif /* ** This routine checks if there is a RESERVED lock held on the specified ** file by this or any other process. If such a lock is held, set *pResOut ** to a non-zero value otherwise *pResOut is set to zero. The return value ** is set to SQLITE_OK unless an I/O error occurs during lock checking. */ static int flockCheckReservedLock(sqlite3_file *id, int *pResOut){ #ifdef SQLITE_DEBUG unixFile *pFile = (unixFile*)id; #else UNUSED_PARAMETER(id); #endif SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; ); assert( pFile ); assert( pFile->eFileLock<=SHARED_LOCK ); /* The flock VFS only ever takes exclusive locks (see function flockLock). ** Therefore, if this connection is holding any lock at all, no other ** connection may be holding a RESERVED lock. So set *pResOut to 0 ** in this case. ** ** Or, this connection may be holding no lock. In that case, set *pResOut to ** 0 as well. The caller will then attempt to take an EXCLUSIVE lock on the ** db in order to roll the hot journal back. If there is another connection ** holding a lock, that attempt will fail and an SQLITE_BUSY returned to ** the user. With other VFS, we try to avoid this, in order to allow a reader ** to proceed while a writer is preparing its transaction. But that won't ** work with the flock VFS - as it always takes EXCLUSIVE locks - so it is ** not a problem in this case. */ *pResOut = 0; return SQLITE_OK; } /* ** Lock the file with the lock specified by parameter eFileLock - one ** of the following: ** ** (1) SHARED_LOCK ** (2) RESERVED_LOCK ** (3) PENDING_LOCK ** (4) EXCLUSIVE_LOCK ** ** Sometimes when requesting one lock state, additional lock states ** are inserted in between. The locking might fail on one of the later ** transitions leaving the lock state different from what it started but ** still short of its goal. The following chart shows the allowed ** transitions and the inserted intermediate states: ** ** UNLOCKED -> SHARED ** SHARED -> RESERVED ** SHARED -> (PENDING) -> EXCLUSIVE ** RESERVED -> (PENDING) -> EXCLUSIVE ** PENDING -> EXCLUSIVE ** ** flock() only really support EXCLUSIVE locks. We track intermediate ** lock states in the sqlite3_file structure, but all locks SHARED or ** above are really EXCLUSIVE locks and exclude all other processes from ** access the file. ** ** This routine will only increase a lock. Use the sqlite3OsUnlock() ** routine to lower a locking level. */ static int flockLock(sqlite3_file *id, int eFileLock) { int rc = SQLITE_OK; unixFile *pFile = (unixFile*)id; assert( pFile ); /* if we already have a lock, it is exclusive. ** Just adjust level and punt on outta here. */ if (pFile->eFileLock > NO_LOCK) { pFile->eFileLock = eFileLock; return SQLITE_OK; } /* grab an exclusive lock */ if (robust_flock(pFile->h, LOCK_EX | LOCK_NB)) { int tErrno = errno; /* didn't get, must be busy */ rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK); if( IS_LOCK_ERROR(rc) ){ storeLastErrno(pFile, tErrno); } } else { /* got it, set the type and return ok */ pFile->eFileLock = eFileLock; } OSTRACE(("LOCK %d %s %s (flock)\n", pFile->h, azFileLock(eFileLock), rc==SQLITE_OK ? "ok" : "failed")); #ifdef SQLITE_IGNORE_FLOCK_LOCK_ERRORS if( (rc & 0xff) == SQLITE_IOERR ){ rc = SQLITE_BUSY; } #endif /* SQLITE_IGNORE_FLOCK_LOCK_ERRORS */ return rc; } /* ** Lower the locking level on file descriptor pFile to eFileLock. eFileLock ** must be either NO_LOCK or SHARED_LOCK. ** ** If the locking level of the file descriptor is already at or below ** the requested locking level, this routine is a no-op. */ static int flockUnlock(sqlite3_file *id, int eFileLock) { unixFile *pFile = (unixFile*)id; assert( pFile ); OSTRACE(("UNLOCK %d %d was %d pid=%d (flock)\n", pFile->h, eFileLock, pFile->eFileLock, osGetpid(0))); assert( eFileLock<=SHARED_LOCK ); /* no-op if possible */ if( pFile->eFileLock==eFileLock ){ return SQLITE_OK; } /* shared can just be set because we always have an exclusive */ if (eFileLock==SHARED_LOCK) { pFile->eFileLock = eFileLock; return SQLITE_OK; } /* no, really, unlock. */ if( robust_flock(pFile->h, LOCK_UN) ){ #ifdef SQLITE_IGNORE_FLOCK_LOCK_ERRORS return SQLITE_OK; #endif /* SQLITE_IGNORE_FLOCK_LOCK_ERRORS */ return SQLITE_IOERR_UNLOCK; }else{ pFile->eFileLock = NO_LOCK; return SQLITE_OK; } } /* ** Close a file. */ static int flockClose(sqlite3_file *id) { assert( id!=0 ); flockUnlock(id, NO_LOCK); return closeUnixFile(id); } #endif /* SQLITE_ENABLE_LOCKING_STYLE && !OS_VXWORK */ /******************* End of the flock lock implementation ********************* ******************************************************************************/ /****************************************************************************** ************************ Begin Named Semaphore Locking ************************ ** ** Named semaphore locking is only supported on VxWorks. ** ** Semaphore locking is like dot-lock and flock in that it really only ** supports EXCLUSIVE locking. Only a single process can read or write ** the database file at a time. This reduces potential concurrency, but ** makes the lock implementation much easier. */ #if OS_VXWORKS /* ** This routine checks if there is a RESERVED lock held on the specified ** file by this or any other process. If such a lock is held, set *pResOut ** to a non-zero value otherwise *pResOut is set to zero. The return value ** is set to SQLITE_OK unless an I/O error occurs during lock checking. */ static int semXCheckReservedLock(sqlite3_file *id, int *pResOut) { int rc = SQLITE_OK; int reserved = 0; unixFile *pFile = (unixFile*)id; SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; ); assert( pFile ); /* Check if a thread in this process holds such a lock */ if( pFile->eFileLock>SHARED_LOCK ){ reserved = 1; } /* Otherwise see if some other process holds it. */ if( !reserved ){ sem_t *pSem = pFile->pInode->pSem; if( sem_trywait(pSem)==-1 ){ int tErrno = errno; if( EAGAIN != tErrno ){ rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_CHECKRESERVEDLOCK); storeLastErrno(pFile, tErrno); } else { /* someone else has the lock when we are in NO_LOCK */ reserved = (pFile->eFileLock < SHARED_LOCK); } }else{ /* we could have it if we want it */ sem_post(pSem); } } OSTRACE(("TEST WR-LOCK %d %d %d (sem)\n", pFile->h, rc, reserved)); *pResOut = reserved; return rc; } /* ** Lock the file with the lock specified by parameter eFileLock - one ** of the following: ** ** (1) SHARED_LOCK ** (2) RESERVED_LOCK ** (3) PENDING_LOCK ** (4) EXCLUSIVE_LOCK ** ** Sometimes when requesting one lock state, additional lock states ** are inserted in between. The locking might fail on one of the later ** transitions leaving the lock state different from what it started but ** still short of its goal. The following chart shows the allowed ** transitions and the inserted intermediate states: ** ** UNLOCKED -> SHARED ** SHARED -> RESERVED ** SHARED -> (PENDING) -> EXCLUSIVE ** RESERVED -> (PENDING) -> EXCLUSIVE ** PENDING -> EXCLUSIVE ** ** Semaphore locks only really support EXCLUSIVE locks. We track intermediate ** lock states in the sqlite3_file structure, but all locks SHARED or ** above are really EXCLUSIVE locks and exclude all other processes from ** access the file. ** ** This routine will only increase a lock. Use the sqlite3OsUnlock() ** routine to lower a locking level. */ static int semXLock(sqlite3_file *id, int eFileLock) { unixFile *pFile = (unixFile*)id; sem_t *pSem = pFile->pInode->pSem; int rc = SQLITE_OK; /* if we already have a lock, it is exclusive. ** Just adjust level and punt on outta here. */ if (pFile->eFileLock > NO_LOCK) { pFile->eFileLock = eFileLock; rc = SQLITE_OK; goto sem_end_lock; } /* lock semaphore now but bail out when already locked. */ if( sem_trywait(pSem)==-1 ){ rc = SQLITE_BUSY; goto sem_end_lock; } /* got it, set the type and return ok */ pFile->eFileLock = eFileLock; sem_end_lock: return rc; } /* ** Lower the locking level on file descriptor pFile to eFileLock. eFileLock ** must be either NO_LOCK or SHARED_LOCK. ** ** If the locking level of the file descriptor is already at or below ** the requested locking level, this routine is a no-op. */ static int semXUnlock(sqlite3_file *id, int eFileLock) { unixFile *pFile = (unixFile*)id; sem_t *pSem = pFile->pInode->pSem; assert( pFile ); assert( pSem ); OSTRACE(("UNLOCK %d %d was %d pid=%d (sem)\n", pFile->h, eFileLock, pFile->eFileLock, osGetpid(0))); assert( eFileLock<=SHARED_LOCK ); /* no-op if possible */ if( pFile->eFileLock==eFileLock ){ return SQLITE_OK; } /* shared can just be set because we always have an exclusive */ if (eFileLock==SHARED_LOCK) { pFile->eFileLock = eFileLock; return SQLITE_OK; } /* no, really unlock. */ if ( sem_post(pSem)==-1 ) { int rc, tErrno = errno; rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK); if( IS_LOCK_ERROR(rc) ){ storeLastErrno(pFile, tErrno); } return rc; } pFile->eFileLock = NO_LOCK; return SQLITE_OK; } /* ** Close a file. */ static int semXClose(sqlite3_file *id) { if( id ){ unixFile *pFile = (unixFile*)id; semXUnlock(id, NO_LOCK); assert( pFile ); assert( unixFileMutexNotheld(pFile) ); unixEnterMutex(); releaseInodeInfo(pFile); unixLeaveMutex(); closeUnixFile(id); } return SQLITE_OK; } #endif /* OS_VXWORKS */ /* ** Named semaphore locking is only available on VxWorks. ** *************** End of the named semaphore lock implementation **************** ******************************************************************************/ /****************************************************************************** *************************** Begin AFP Locking ********************************* ** ** AFP is the Apple Filing Protocol. AFP is a network filesystem found ** on Apple Macintosh computers - both OS9 and OSX. ** ** Third-party implementations of AFP are available. But this code here ** only works on OSX. */ #if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE /* ** The afpLockingContext structure contains all afp lock specific state */ typedef struct afpLockingContext afpLockingContext; struct afpLockingContext { int reserved; const char *dbPath; /* Name of the open file */ }; struct ByteRangeLockPB2 { unsigned long long offset; /* offset to first byte to lock */ unsigned long long length; /* nbr of bytes to lock */ unsigned long long retRangeStart; /* nbr of 1st byte locked if successful */ unsigned char unLockFlag; /* 1 = unlock, 0 = lock */ unsigned char startEndFlag; /* 1=rel to end of fork, 0=rel to start */ int fd; /* file desc to assoc this lock with */ }; #define afpfsByteRangeLock2FSCTL _IOWR('z', 23, struct ByteRangeLockPB2) /* ** This is a utility for setting or clearing a bit-range lock on an ** AFP filesystem. ** ** Return SQLITE_OK on success, SQLITE_BUSY on failure. */ static int afpSetLock( const char *path, /* Name of the file to be locked or unlocked */ unixFile *pFile, /* Open file descriptor on path */ unsigned long long offset, /* First byte to be locked */ unsigned long long length, /* Number of bytes to lock */ int setLockFlag /* True to set lock. False to clear lock */ ){ struct ByteRangeLockPB2 pb; int err; pb.unLockFlag = setLockFlag ? 0 : 1; pb.startEndFlag = 0; pb.offset = offset; pb.length = length; pb.fd = pFile->h; OSTRACE(("AFPSETLOCK [%s] for %d%s in range %llx:%llx\n", (setLockFlag?"ON":"OFF"), pFile->h, (pb.fd==-1?"[testval-1]":""), offset, length)); err = fsctl(path, afpfsByteRangeLock2FSCTL, &pb, 0); if ( err==-1 ) { int rc; int tErrno = errno; OSTRACE(("AFPSETLOCK failed to fsctl() '%s' %d %s\n", path, tErrno, strerror(tErrno))); #ifdef SQLITE_IGNORE_AFP_LOCK_ERRORS rc = SQLITE_BUSY; #else rc = sqliteErrorFromPosixError(tErrno, setLockFlag ? SQLITE_IOERR_LOCK : SQLITE_IOERR_UNLOCK); #endif /* SQLITE_IGNORE_AFP_LOCK_ERRORS */ if( IS_LOCK_ERROR(rc) ){ storeLastErrno(pFile, tErrno); } return rc; } else { return SQLITE_OK; } } /* ** This routine checks if there is a RESERVED lock held on the specified ** file by this or any other process. If such a lock is held, set *pResOut ** to a non-zero value otherwise *pResOut is set to zero. The return value ** is set to SQLITE_OK unless an I/O error occurs during lock checking. */ static int afpCheckReservedLock(sqlite3_file *id, int *pResOut){ int rc = SQLITE_OK; int reserved = 0; unixFile *pFile = (unixFile*)id; afpLockingContext *context; SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; ); assert( pFile ); context = (afpLockingContext *) pFile->lockingContext; if( context->reserved ){ *pResOut = 1; return SQLITE_OK; } sqlite3_mutex_enter(pFile->pInode->pLockMutex); /* Check if a thread in this process holds such a lock */ if( pFile->pInode->eFileLock>SHARED_LOCK ){ reserved = 1; } /* Otherwise see if some other process holds it. */ if( !reserved ){ /* lock the RESERVED byte */ int lrc = afpSetLock(context->dbPath, pFile, RESERVED_BYTE, 1,1); if( SQLITE_OK==lrc ){ /* if we succeeded in taking the reserved lock, unlock it to restore ** the original state */ lrc = afpSetLock(context->dbPath, pFile, RESERVED_BYTE, 1, 0); } else { /* if we failed to get the lock then someone else must have it */ reserved = 1; } if( IS_LOCK_ERROR(lrc) ){ rc=lrc; } } sqlite3_mutex_leave(pFile->pInode->pLockMutex); OSTRACE(("TEST WR-LOCK %d %d %d (afp)\n", pFile->h, rc, reserved)); *pResOut = reserved; return rc; } /* ** Lock the file with the lock specified by parameter eFileLock - one ** of the following: ** ** (1) SHARED_LOCK ** (2) RESERVED_LOCK ** (3) PENDING_LOCK ** (4) EXCLUSIVE_LOCK ** ** Sometimes when requesting one lock state, additional lock states ** are inserted in between. The locking might fail on one of the later ** transitions leaving the lock state different from what it started but ** still short of its goal. The following chart shows the allowed ** transitions and the inserted intermediate states: ** ** UNLOCKED -> SHARED ** SHARED -> RESERVED ** SHARED -> (PENDING) -> EXCLUSIVE ** RESERVED -> (PENDING) -> EXCLUSIVE ** PENDING -> EXCLUSIVE ** ** This routine will only increase a lock. Use the sqlite3OsUnlock() ** routine to lower a locking level. */ static int afpLock(sqlite3_file *id, int eFileLock){ int rc = SQLITE_OK; unixFile *pFile = (unixFile*)id; unixInodeInfo *pInode = pFile->pInode; afpLockingContext *context = (afpLockingContext *) pFile->lockingContext; assert( pFile ); OSTRACE(("LOCK %d %s was %s(%s,%d) pid=%d (afp)\n", pFile->h, azFileLock(eFileLock), azFileLock(pFile->eFileLock), azFileLock(pInode->eFileLock), pInode->nShared , osGetpid(0))); /* If there is already a lock of this type or more restrictive on the ** unixFile, do nothing. Don't use the afp_end_lock: exit path, as ** unixEnterMutex() hasn't been called yet. */ if( pFile->eFileLock>=eFileLock ){ OSTRACE(("LOCK %d %s ok (already held) (afp)\n", pFile->h, azFileLock(eFileLock))); return SQLITE_OK; } /* Make sure the locking sequence is correct ** (1) We never move from unlocked to anything higher than shared lock. ** (2) SQLite never explicitly requests a pending lock. ** (3) A shared lock is always held when a reserve lock is requested. */ assert( pFile->eFileLock!=NO_LOCK || eFileLock==SHARED_LOCK ); assert( eFileLock!=PENDING_LOCK ); assert( eFileLock!=RESERVED_LOCK || pFile->eFileLock==SHARED_LOCK ); /* This mutex is needed because pFile->pInode is shared across threads */ pInode = pFile->pInode; sqlite3_mutex_enter(pInode->pLockMutex); /* If some thread using this PID has a lock via a different unixFile* ** handle that precludes the requested lock, return BUSY. */ if( (pFile->eFileLock!=pInode->eFileLock && (pInode->eFileLock>=PENDING_LOCK || eFileLock>SHARED_LOCK)) ){ rc = SQLITE_BUSY; goto afp_end_lock; } /* If a SHARED lock is requested, and some thread using this PID already ** has a SHARED or RESERVED lock, then increment reference counts and ** return SQLITE_OK. */ if( eFileLock==SHARED_LOCK && (pInode->eFileLock==SHARED_LOCK || pInode->eFileLock==RESERVED_LOCK) ){ assert( eFileLock==SHARED_LOCK ); assert( pFile->eFileLock==0 ); assert( pInode->nShared>0 ); pFile->eFileLock = SHARED_LOCK; pInode->nShared++; pInode->nLock++; goto afp_end_lock; } /* A PENDING lock is needed before acquiring a SHARED lock and before ** acquiring an EXCLUSIVE lock. For the SHARED lock, the PENDING will ** be released. */ if( eFileLock==SHARED_LOCK || (eFileLock==EXCLUSIVE_LOCK && pFile->eFileLock<PENDING_LOCK) ){ int failed; failed = afpSetLock(context->dbPath, pFile, PENDING_BYTE, 1, 1); if (failed) { rc = failed; goto afp_end_lock; } } /* If control gets to this point, then actually go ahead and make ** operating system calls for the specified lock. */ if( eFileLock==SHARED_LOCK ){ int lrc1, lrc2, lrc1Errno = 0; long lk, mask; assert( pInode->nShared==0 ); assert( pInode->eFileLock==0 ); mask = (sizeof(long)==8) ? LARGEST_INT64 : 0x7fffffff; /* Now get the read-lock SHARED_LOCK */ /* note that the quality of the randomness doesn't matter that much */ lk = random(); pInode->sharedByte = (lk & mask)%(SHARED_SIZE - 1); lrc1 = afpSetLock(context->dbPath, pFile, SHARED_FIRST+pInode->sharedByte, 1, 1); if( IS_LOCK_ERROR(lrc1) ){ lrc1Errno = pFile->lastErrno; } /* Drop the temporary PENDING lock */ lrc2 = afpSetLock(context->dbPath, pFile, PENDING_BYTE, 1, 0); if( IS_LOCK_ERROR(lrc1) ) { storeLastErrno(pFile, lrc1Errno); rc = lrc1; goto afp_end_lock; } else if( IS_LOCK_ERROR(lrc2) ){ rc = lrc2; goto afp_end_lock; } else if( lrc1 != SQLITE_OK ) { rc = lrc1; } else { pFile->eFileLock = SHARED_LOCK; pInode->nLock++; pInode->nShared = 1; } }else if( eFileLock==EXCLUSIVE_LOCK && pInode->nShared>1 ){ /* We are trying for an exclusive lock but another thread in this ** same process is still holding a shared lock. */ rc = SQLITE_BUSY; }else{ /* The request was for a RESERVED or EXCLUSIVE lock. It is ** assumed that there is a SHARED or greater lock on the file ** already. */ int failed = 0; assert( 0!=pFile->eFileLock ); if (eFileLock >= RESERVED_LOCK && pFile->eFileLock < RESERVED_LOCK) { /* Acquire a RESERVED lock */ failed = afpSetLock(context->dbPath, pFile, RESERVED_BYTE, 1,1); if( !failed ){ context->reserved = 1; } } if (!failed && eFileLock == EXCLUSIVE_LOCK) { /* Acquire an EXCLUSIVE lock */ /* Remove the shared lock before trying the range. we'll need to ** reestablish the shared lock if we can't get the afpUnlock */ if( !(failed = afpSetLock(context->dbPath, pFile, SHARED_FIRST + pInode->sharedByte, 1, 0)) ){ int failed2 = SQLITE_OK; /* now attempt to get the exclusive lock range */ failed = afpSetLock(context->dbPath, pFile, SHARED_FIRST, SHARED_SIZE, 1); if( failed && (failed2 = afpSetLock(context->dbPath, pFile, SHARED_FIRST + pInode->sharedByte, 1, 1)) ){ /* Can't reestablish the shared lock. Sqlite can't deal, this is ** a critical I/O error */ rc = ((failed & 0xff) == SQLITE_IOERR) ? failed2 : SQLITE_IOERR_LOCK; goto afp_end_lock; } }else{ rc = failed; } } if( failed ){ rc = failed; } } if( rc==SQLITE_OK ){ pFile->eFileLock = eFileLock; pInode->eFileLock = eFileLock; }else if( eFileLock==EXCLUSIVE_LOCK ){ pFile->eFileLock = PENDING_LOCK; pInode->eFileLock = PENDING_LOCK; } afp_end_lock: sqlite3_mutex_leave(pInode->pLockMutex); OSTRACE(("LOCK %d %s %s (afp)\n", pFile->h, azFileLock(eFileLock), rc==SQLITE_OK ? "ok" : "failed")); return rc; } /* ** Lower the locking level on file descriptor pFile to eFileLock. eFileLock ** must be either NO_LOCK or SHARED_LOCK. ** ** If the locking level of the file descriptor is already at or below ** the requested locking level, this routine is a no-op. */ static int afpUnlock(sqlite3_file *id, int eFileLock) { int rc = SQLITE_OK; unixFile *pFile = (unixFile*)id; unixInodeInfo *pInode; afpLockingContext *context = (afpLockingContext *) pFile->lockingContext; int skipShared = 0; assert( pFile ); OSTRACE(("UNLOCK %d %d was %d(%d,%d) pid=%d (afp)\n", pFile->h, eFileLock, pFile->eFileLock, pFile->pInode->eFileLock, pFile->pInode->nShared, osGetpid(0))); assert( eFileLock<=SHARED_LOCK ); if( pFile->eFileLock<=eFileLock ){ return SQLITE_OK; } pInode = pFile->pInode; sqlite3_mutex_enter(pInode->pLockMutex); assert( pInode->nShared!=0 ); if( pFile->eFileLock>SHARED_LOCK ){ assert( pInode->eFileLock==pFile->eFileLock ); #ifdef SQLITE_DEBUG /* When reducing a lock such that other processes can start ** reading the database file again, make sure that the ** transaction counter was updated if any part of the database ** file changed. If the transaction counter is not updated, ** other connections to the same file might not realize that ** the file has changed and hence might not know to flush their ** cache. The use of a stale cache can lead to database corruption. */ assert( pFile->inNormalWrite==0 || pFile->dbUpdate==0 || pFile->transCntrChng==1 ); pFile->inNormalWrite = 0; #endif if( pFile->eFileLock==EXCLUSIVE_LOCK ){ rc = afpSetLock(context->dbPath, pFile, SHARED_FIRST, SHARED_SIZE, 0); if( rc==SQLITE_OK && (eFileLock==SHARED_LOCK || pInode->nShared>1) ){ /* only re-establish the shared lock if necessary */ int sharedLockByte = SHARED_FIRST+pInode->sharedByte; rc = afpSetLock(context->dbPath, pFile, sharedLockByte, 1, 1); } else { skipShared = 1; } } if( rc==SQLITE_OK && pFile->eFileLock>=PENDING_LOCK ){ rc = afpSetLock(context->dbPath, pFile, PENDING_BYTE, 1, 0); } if( rc==SQLITE_OK && pFile->eFileLock>=RESERVED_LOCK && context->reserved ){ rc = afpSetLock(context->dbPath, pFile, RESERVED_BYTE, 1, 0); if( !rc ){ context->reserved = 0; } } if( rc==SQLITE_OK && (eFileLock==SHARED_LOCK || pInode->nShared>1)){ pInode->eFileLock = SHARED_LOCK; } } if( rc==SQLITE_OK && eFileLock==NO_LOCK ){ /* Decrement the shared lock counter. Release the lock using an ** OS call only when all threads in this same process have released ** the lock. */ unsigned long long sharedLockByte = SHARED_FIRST+pInode->sharedByte; pInode->nShared--; if( pInode->nShared==0 ){ if( !skipShared ){ rc = afpSetLock(context->dbPath, pFile, sharedLockByte, 1, 0); } if( !rc ){ pInode->eFileLock = NO_LOCK; pFile->eFileLock = NO_LOCK; } } if( rc==SQLITE_OK ){ pInode->nLock--; assert( pInode->nLock>=0 ); if( pInode->nLock==0 ) closePendingFds(pFile); } } sqlite3_mutex_leave(pInode->pLockMutex); if( rc==SQLITE_OK ){ pFile->eFileLock = eFileLock; } return rc; } /* ** Close a file & cleanup AFP specific locking context */ static int afpClose(sqlite3_file *id) { int rc = SQLITE_OK; unixFile *pFile = (unixFile*)id; assert( id!=0 ); afpUnlock(id, NO_LOCK); assert( unixFileMutexNotheld(pFile) ); unixEnterMutex(); if( pFile->pInode ){ unixInodeInfo *pInode = pFile->pInode; sqlite3_mutex_enter(pInode->pLockMutex); if( pInode->nLock ){ /* If there are outstanding locks, do not actually close the file just ** yet because that would clear those locks. Instead, add the file ** descriptor to pInode->aPending. It will be automatically closed when ** the last lock is cleared. */ setPendingFd(pFile); } sqlite3_mutex_leave(pInode->pLockMutex); } releaseInodeInfo(pFile); sqlite3_free(pFile->lockingContext); rc = closeUnixFile(id); unixLeaveMutex(); return rc; } #endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */ /* ** The code above is the AFP lock implementation. The code is specific ** to MacOSX and does not work on other unix platforms. No alternative ** is available. If you don't compile for a mac, then the "unix-afp" ** VFS is not available. ** ********************* End of the AFP lock implementation ********************** ******************************************************************************/ /****************************************************************************** *************************** Begin NFS Locking ********************************/ #if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE /* ** Lower the locking level on file descriptor pFile to eFileLock. eFileLock ** must be either NO_LOCK or SHARED_LOCK. ** ** If the locking level of the file descriptor is already at or below ** the requested locking level, this routine is a no-op. */ static int nfsUnlock(sqlite3_file *id, int eFileLock){ return posixUnlock(id, eFileLock, 1); } #endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */ /* ** The code above is the NFS lock implementation. The code is specific ** to MacOSX and does not work on other unix platforms. No alternative ** is available. ** ********************* End of the NFS lock implementation ********************** ******************************************************************************/ /****************************************************************************** **************** Non-locking sqlite3_file methods ***************************** ** ** The next division contains implementations for all methods of the ** sqlite3_file object other than the locking methods. The locking ** methods were defined in divisions above (one locking method per ** division). Those methods that are common to all locking modes ** are gather together into this division. */ /* ** Seek to the offset passed as the second argument, then read cnt ** bytes into pBuf. Return the number of bytes actually read. ** ** To avoid stomping the errno value on a failed read the lastErrno value ** is set before returning. */ static int seekAndRead(unixFile *id, sqlite3_int64 offset, void *pBuf, int cnt){ int got; int prior = 0; #if (!defined(USE_PREAD) && !defined(USE_PREAD64)) i64 newOffset; #endif TIMER_START; assert( cnt==(cnt&0x1ffff) ); assert( id->h>2 ); do{ #if defined(USE_PREAD) got = osPread(id->h, pBuf, cnt, offset); SimulateIOError( got = -1 ); #elif defined(USE_PREAD64) got = osPread64(id->h, pBuf, cnt, offset); SimulateIOError( got = -1 ); #else newOffset = lseek(id->h, offset, SEEK_SET); SimulateIOError( newOffset = -1 ); if( newOffset<0 ){ storeLastErrno((unixFile*)id, errno); return -1; } got = osRead(id->h, pBuf, cnt); #endif if( got==cnt ) break; if( got<0 ){ if( errno==EINTR ){ got = 1; continue; } prior = 0; storeLastErrno((unixFile*)id, errno); break; }else if( got>0 ){ cnt -= got; offset += got; prior += got; pBuf = (void*)(got + (char*)pBuf); } }while( got>0 ); TIMER_END; OSTRACE(("READ %-3d %5d %7lld %llu\n", id->h, got+prior, offset-prior, TIMER_ELAPSED)); return got+prior; } /* ** Read data from a file into a buffer. Return SQLITE_OK if all ** bytes were read successfully and SQLITE_IOERR if anything goes ** wrong. */ static int unixRead( sqlite3_file *id, void *pBuf, int amt, sqlite3_int64 offset ){ unixFile *pFile = (unixFile *)id; int got; assert( id ); assert( offset>=0 ); assert( amt>0 ); /* If this is a database file (not a journal, super-journal or temp ** file), the bytes in the locking range should never be read or written. */ #if 0 assert( pFile->pPreallocatedUnused==0 || offset>=PENDING_BYTE+512 || offset+amt<=PENDING_BYTE ); #endif #if SQLITE_MAX_MMAP_SIZE>0 /* Deal with as much of this read request as possible by transferring ** data from the memory mapping using memcpy(). */ if( offset<pFile->mmapSize ){ if( offset+amt <= pFile->mmapSize ){ memcpy(pBuf, &((u8 *)(pFile->pMapRegion))[offset], amt); return SQLITE_OK; }else{ int nCopy = pFile->mmapSize - offset; memcpy(pBuf, &((u8 *)(pFile->pMapRegion))[offset], nCopy); pBuf = &((u8 *)pBuf)[nCopy]; amt -= nCopy; offset += nCopy; } } #endif got = seekAndRead(pFile, offset, pBuf, amt); if( got==amt ){ return SQLITE_OK; }else if( got<0 ){ /* pFile->lastErrno has been set by seekAndRead(). ** Usually we return SQLITE_IOERR_READ here, though for some ** kinds of errors we return SQLITE_IOERR_CORRUPTFS. The ** SQLITE_IOERR_CORRUPTFS will be converted into SQLITE_CORRUPT ** prior to returning to the application by the sqlite3ApiExit() ** routine. */ switch( pFile->lastErrno ){ case ERANGE: case EIO: #ifdef ENXIO case ENXIO: #endif #ifdef EDEVERR case EDEVERR: #endif return SQLITE_IOERR_CORRUPTFS; } return SQLITE_IOERR_READ; }else{ storeLastErrno(pFile, 0); /* not a system error */ /* Unread parts of the buffer must be zero-filled */ memset(&((char*)pBuf)[got], 0, amt-got); return SQLITE_IOERR_SHORT_READ; } } /* ** Attempt to seek the file-descriptor passed as the first argument to ** absolute offset iOff, then attempt to write nBuf bytes of data from ** pBuf to it. If an error occurs, return -1 and set *piErrno. Otherwise, ** return the actual number of bytes written (which may be less than ** nBuf). */ static int seekAndWriteFd( int fd, /* File descriptor to write to */ i64 iOff, /* File offset to begin writing at */ const void *pBuf, /* Copy data from this buffer to the file */ int nBuf, /* Size of buffer pBuf in bytes */ int *piErrno /* OUT: Error number if error occurs */ ){ int rc = 0; /* Value returned by system call */ assert( nBuf==(nBuf&0x1ffff) ); assert( fd>2 ); assert( piErrno!=0 ); nBuf &= 0x1ffff; TIMER_START; #if defined(USE_PREAD) do{ rc = (int)osPwrite(fd, pBuf, nBuf, iOff); }while( rc<0 && errno==EINTR ); #elif defined(USE_PREAD64) do{ rc = (int)osPwrite64(fd, pBuf, nBuf, iOff);}while( rc<0 && errno==EINTR); #else do{ i64 iSeek = lseek(fd, iOff, SEEK_SET); SimulateIOError( iSeek = -1 ); if( iSeek<0 ){ rc = -1; break; } rc = osWrite(fd, pBuf, nBuf); }while( rc<0 && errno==EINTR ); #endif TIMER_END; OSTRACE(("WRITE %-3d %5d %7lld %llu\n", fd, rc, iOff, TIMER_ELAPSED)); if( rc<0 ) *piErrno = errno; return rc; } /* ** Seek to the offset in id->offset then read cnt bytes into pBuf. ** Return the number of bytes actually read. Update the offset. ** ** To avoid stomping the errno value on a failed write the lastErrno value ** is set before returning. */ static int seekAndWrite(unixFile *id, i64 offset, const void *pBuf, int cnt){ return seekAndWriteFd(id->h, offset, pBuf, cnt, &id->lastErrno); } /* ** Write data from a buffer into a file. Return SQLITE_OK on success ** or some other error code on failure. */ static int unixWrite( sqlite3_file *id, const void *pBuf, int amt, sqlite3_int64 offset ){ unixFile *pFile = (unixFile*)id; int wrote = 0; assert( id ); assert( amt>0 ); /* If this is a database file (not a journal, super-journal or temp ** file), the bytes in the locking range should never be read or written. */ #if 0 assert( pFile->pPreallocatedUnused==0 || offset>=PENDING_BYTE+512 || offset+amt<=PENDING_BYTE ); #endif #ifdef SQLITE_DEBUG /* If we are doing a normal write to a database file (as opposed to ** doing a hot-journal rollback or a write to some file other than a ** normal database file) then record the fact that the database ** has changed. If the transaction counter is modified, record that ** fact too. */ if( pFile->inNormalWrite ){ pFile->dbUpdate = 1; /* The database has been modified */ if( offset<=24 && offset+amt>=27 ){ int rc; char oldCntr[4]; SimulateIOErrorBenign(1); rc = seekAndRead(pFile, 24, oldCntr, 4); SimulateIOErrorBenign(0); if( rc!=4 || memcmp(oldCntr, &((char*)pBuf)[24-offset], 4)!=0 ){ pFile->transCntrChng = 1; /* The transaction counter has changed */ } } } #endif #if defined(SQLITE_MMAP_READWRITE) && SQLITE_MAX_MMAP_SIZE>0 /* Deal with as much of this write request as possible by transferring ** data from the memory mapping using memcpy(). */ if( offset<pFile->mmapSize ){ if( offset+amt <= pFile->mmapSize ){ memcpy(&((u8 *)(pFile->pMapRegion))[offset], pBuf, amt); return SQLITE_OK; }else{ int nCopy = pFile->mmapSize - offset; memcpy(&((u8 *)(pFile->pMapRegion))[offset], pBuf, nCopy); pBuf = &((u8 *)pBuf)[nCopy]; amt -= nCopy; offset += nCopy; } } #endif while( (wrote = seekAndWrite(pFile, offset, pBuf, amt))<amt && wrote>0 ){ amt -= wrote; offset += wrote; pBuf = &((char*)pBuf)[wrote]; } SimulateIOError(( wrote=(-1), amt=1 )); SimulateDiskfullError(( wrote=0, amt=1 )); if( amt>wrote ){ if( wrote<0 && pFile->lastErrno!=ENOSPC ){ /* lastErrno set by seekAndWrite */ return SQLITE_IOERR_WRITE; }else{ storeLastErrno(pFile, 0); /* not a system error */ return SQLITE_FULL; } } return SQLITE_OK; } #ifdef SQLITE_TEST /* ** Count the number of fullsyncs and normal syncs. This is used to test ** that syncs and fullsyncs are occurring at the right times. */ int sqlite3_sync_count = 0; int sqlite3_fullsync_count = 0; #endif /* ** We do not trust systems to provide a working fdatasync(). Some do. ** Others do no. To be safe, we will stick with the (slightly slower) ** fsync(). If you know that your system does support fdatasync() correctly, ** then simply compile with -Dfdatasync=fdatasync or -DHAVE_FDATASYNC */ #if !defined(fdatasync) && !HAVE_FDATASYNC # define fdatasync fsync #endif /* ** Define HAVE_FULLFSYNC to 0 or 1 depending on whether or not ** the F_FULLFSYNC macro is defined. F_FULLFSYNC is currently ** only available on Mac OS X. But that could change. */ #ifdef F_FULLFSYNC # define HAVE_FULLFSYNC 1 #else # define HAVE_FULLFSYNC 0 #endif /* ** The fsync() system call does not work as advertised on many ** unix systems. The following procedure is an attempt to make ** it work better. ** ** The SQLITE_NO_SYNC macro disables all fsync()s. This is useful ** for testing when we want to run through the test suite quickly. ** You are strongly advised *not* to deploy with SQLITE_NO_SYNC ** enabled, however, since with SQLITE_NO_SYNC enabled, an OS crash ** or power failure will likely corrupt the database file. ** ** SQLite sets the dataOnly flag if the size of the file is unchanged. ** The idea behind dataOnly is that it should only write the file content ** to disk, not the inode. We only set dataOnly if the file size is ** unchanged since the file size is part of the inode. However, ** Ted Ts'o tells us that fdatasync() will also write the inode if the ** file size has changed. The only real difference between fdatasync() ** and fsync(), Ted tells us, is that fdatasync() will not flush the ** inode if the mtime or owner or other inode attributes have changed. ** We only care about the file size, not the other file attributes, so ** as far as SQLite is concerned, an fdatasync() is always adequate. ** So, we always use fdatasync() if it is available, regardless of ** the value of the dataOnly flag. */ static int full_fsync(int fd, int fullSync, int dataOnly){ int rc; /* The following "ifdef/elif/else/" block has the same structure as ** the one below. It is replicated here solely to avoid cluttering ** up the real code with the UNUSED_PARAMETER() macros. */ #ifdef SQLITE_NO_SYNC UNUSED_PARAMETER(fd); UNUSED_PARAMETER(fullSync); UNUSED_PARAMETER(dataOnly); #elif HAVE_FULLFSYNC UNUSED_PARAMETER(dataOnly); #else UNUSED_PARAMETER(fullSync); UNUSED_PARAMETER(dataOnly); #endif /* Record the number of times that we do a normal fsync() and ** FULLSYNC. This is used during testing to verify that this procedure ** gets called with the correct arguments. */ #ifdef SQLITE_TEST if( fullSync ) sqlite3_fullsync_count++; sqlite3_sync_count++; #endif /* If we compiled with the SQLITE_NO_SYNC flag, then syncing is a ** no-op. But go ahead and call fstat() to validate the file ** descriptor as we need a method to provoke a failure during ** coverage testing. */ #ifdef SQLITE_NO_SYNC { struct stat buf; rc = osFstat(fd, &buf); } #elif HAVE_FULLFSYNC if( fullSync ){ rc = osFcntl(fd, F_FULLFSYNC, 0); }else{ rc = 1; } /* If the FULLFSYNC failed, fall back to attempting an fsync(). ** It shouldn't be possible for fullfsync to fail on the local ** file system (on OSX), so failure indicates that FULLFSYNC ** isn't supported for this file system. So, attempt an fsync ** and (for now) ignore the overhead of a superfluous fcntl call. ** It'd be better to detect fullfsync support once and avoid ** the fcntl call every time sync is called. */ if( rc ) rc = fsync(fd); #elif defined(__APPLE__) /* fdatasync() on HFS+ doesn't yet flush the file size if it changed correctly ** so currently we default to the macro that redefines fdatasync to fsync */ rc = fsync(fd); #else rc = fdatasync(fd); #if OS_VXWORKS if( rc==-1 && errno==ENOTSUP ){ rc = fsync(fd); } #endif /* OS_VXWORKS */ #endif /* ifdef SQLITE_NO_SYNC elif HAVE_FULLFSYNC */ if( OS_VXWORKS && rc!= -1 ){ rc = 0; } return rc; } /* ** Open a file descriptor to the directory containing file zFilename. ** If successful, *pFd is set to the opened file descriptor and ** SQLITE_OK is returned. If an error occurs, either SQLITE_NOMEM ** or SQLITE_CANTOPEN is returned and *pFd is set to an undefined ** value. ** ** The directory file descriptor is used for only one thing - to ** fsync() a directory to make sure file creation and deletion events ** are flushed to disk. Such fsyncs are not needed on newer ** journaling filesystems, but are required on older filesystems. ** ** This routine can be overridden using the xSetSysCall interface. ** The ability to override this routine was added in support of the ** chromium sandbox. Opening a directory is a security risk (we are ** told) so making it overrideable allows the chromium sandbox to ** replace this routine with a harmless no-op. To make this routine ** a no-op, replace it with a stub that returns SQLITE_OK but leaves ** *pFd set to a negative number. ** ** If SQLITE_OK is returned, the caller is responsible for closing ** the file descriptor *pFd using close(). */ static int openDirectory(const char *zFilename, int *pFd){ int ii; int fd = -1; char zDirname[MAX_PATHNAME+1]; sqlite3_snprintf(MAX_PATHNAME, zDirname, "%s", zFilename); for(ii=(int)strlen(zDirname); ii>0 && zDirname[ii]!='/'; ii--); if( ii>0 ){ zDirname[ii] = '\0'; }else{ if( zDirname[0]!='/' ) zDirname[0] = '.'; zDirname[1] = 0; } fd = robust_open(zDirname, O_RDONLY|O_BINARY, 0); if( fd>=0 ){ OSTRACE(("OPENDIR %-3d %s\n", fd, zDirname)); } *pFd = fd; if( fd>=0 ) return SQLITE_OK; return unixLogError(SQLITE_CANTOPEN_BKPT, "openDirectory", zDirname); } /* ** Make sure all writes to a particular file are committed to disk. ** ** If dataOnly==0 then both the file itself and its metadata (file ** size, access time, etc) are synced. If dataOnly!=0 then only the ** file data is synced. ** ** Under Unix, also make sure that the directory entry for the file ** has been created by fsync-ing the directory that contains the file. ** If we do not do this and we encounter a power failure, the directory ** entry for the journal might not exist after we reboot. The next ** SQLite to access the file will not know that the journal exists (because ** the directory entry for the journal was never created) and the transaction ** will not roll back - possibly leading to database corruption. */ static int unixSync(sqlite3_file *id, int flags){ int rc; unixFile *pFile = (unixFile*)id; int isDataOnly = (flags&SQLITE_SYNC_DATAONLY); int isFullsync = (flags&0x0F)==SQLITE_SYNC_FULL; /* Check that one of SQLITE_SYNC_NORMAL or FULL was passed */ assert((flags&0x0F)==SQLITE_SYNC_NORMAL || (flags&0x0F)==SQLITE_SYNC_FULL ); /* Unix cannot, but some systems may return SQLITE_FULL from here. This ** line is to test that doing so does not cause any problems. */ SimulateDiskfullError( return SQLITE_FULL ); assert( pFile ); OSTRACE(("SYNC %-3d\n", pFile->h)); rc = full_fsync(pFile->h, isFullsync, isDataOnly); SimulateIOError( rc=1 ); if( rc ){ storeLastErrno(pFile, errno); return unixLogError(SQLITE_IOERR_FSYNC, "full_fsync", pFile->zPath); } /* Also fsync the directory containing the file if the DIRSYNC flag ** is set. This is a one-time occurrence. Many systems (examples: AIX) ** are unable to fsync a directory, so ignore errors on the fsync. */ if( pFile->ctrlFlags & UNIXFILE_DIRSYNC ){ int dirfd; OSTRACE(("DIRSYNC %s (have_fullfsync=%d fullsync=%d)\n", pFile->zPath, HAVE_FULLFSYNC, isFullsync)); rc = osOpenDirectory(pFile->zPath, &dirfd); if( rc==SQLITE_OK ){ full_fsync(dirfd, 0, 0); robust_close(pFile, dirfd, __LINE__); }else{ assert( rc==SQLITE_CANTOPEN ); rc = SQLITE_OK; } pFile->ctrlFlags &= ~UNIXFILE_DIRSYNC; } return rc; } /* ** Truncate an open file to a specified size */ static int unixTruncate(sqlite3_file *id, i64 nByte){ unixFile *pFile = (unixFile *)id; int rc; assert( pFile ); SimulateIOError( return SQLITE_IOERR_TRUNCATE ); /* If the user has configured a chunk-size for this file, truncate the ** file so that it consists of an integer number of chunks (i.e. the ** actual file size after the operation may be larger than the requested ** size). */ if( pFile->szChunk>0 ){ nByte = ((nByte + pFile->szChunk - 1)/pFile->szChunk) * pFile->szChunk; } rc = robust_ftruncate(pFile->h, nByte); if( rc ){ storeLastErrno(pFile, errno); return unixLogError(SQLITE_IOERR_TRUNCATE, "ftruncate", pFile->zPath); }else{ #ifdef SQLITE_DEBUG /* If we are doing a normal write to a database file (as opposed to ** doing a hot-journal rollback or a write to some file other than a ** normal database file) and we truncate the file to zero length, ** that effectively updates the change counter. This might happen ** when restoring a database using the backup API from a zero-length ** source. */ if( pFile->inNormalWrite && nByte==0 ){ pFile->transCntrChng = 1; } #endif #if SQLITE_MAX_MMAP_SIZE>0 /* If the file was just truncated to a size smaller than the currently ** mapped region, reduce the effective mapping size as well. SQLite will ** use read() and write() to access data beyond this point from now on. */ if( nByte<pFile->mmapSize ){ pFile->mmapSize = nByte; } #endif return SQLITE_OK; } } /* ** Determine the current size of a file in bytes */ static int unixFileSize(sqlite3_file *id, i64 *pSize){ int rc; struct stat buf; assert( id ); rc = osFstat(((unixFile*)id)->h, &buf); SimulateIOError( rc=1 ); if( rc!=0 ){ storeLastErrno((unixFile*)id, errno); return SQLITE_IOERR_FSTAT; } *pSize = buf.st_size; /* When opening a zero-size database, the findInodeInfo() procedure ** writes a single byte into that file in order to work around a bug ** in the OS-X msdos filesystem. In order to avoid problems with upper ** layers, we need to report this file size as zero even though it is ** really 1. Ticket #3260. */ if( *pSize==1 ) *pSize = 0; return SQLITE_OK; } #if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__) /* ** Handler for proxy-locking file-control verbs. Defined below in the ** proxying locking division. */ static int proxyFileControl(sqlite3_file*,int,void*); #endif /* ** This function is called to handle the SQLITE_FCNTL_SIZE_HINT ** file-control operation. Enlarge the database to nBytes in size ** (rounded up to the next chunk-size). If the database is already ** nBytes or larger, this routine is a no-op. */ static int fcntlSizeHint(unixFile *pFile, i64 nByte){ if( pFile->szChunk>0 ){ i64 nSize; /* Required file size */ struct stat buf; /* Used to hold return values of fstat() */ if( osFstat(pFile->h, &buf) ){ return SQLITE_IOERR_FSTAT; } nSize = ((nByte+pFile->szChunk-1) / pFile->szChunk) * pFile->szChunk; if( nSize>(i64)buf.st_size ){ #if defined(HAVE_POSIX_FALLOCATE) && HAVE_POSIX_FALLOCATE /* The code below is handling the return value of osFallocate() ** correctly. posix_fallocate() is defined to "returns zero on success, ** or an error number on failure". See the manpage for details. */ int err; do{ err = osFallocate(pFile->h, buf.st_size, nSize-buf.st_size); }while( err==EINTR ); if( err && err!=EINVAL ) return SQLITE_IOERR_WRITE; #else /* If the OS does not have posix_fallocate(), fake it. Write a ** single byte to the last byte in each block that falls entirely ** within the extended region. Then, if required, a single byte ** at offset (nSize-1), to set the size of the file correctly. ** This is a similar technique to that used by glibc on systems ** that do not have a real fallocate() call. */ int nBlk = buf.st_blksize; /* File-system block size */ int nWrite = 0; /* Number of bytes written by seekAndWrite */ i64 iWrite; /* Next offset to write to */ iWrite = (buf.st_size/nBlk)*nBlk + nBlk - 1; assert( iWrite>=buf.st_size ); assert( ((iWrite+1)%nBlk)==0 ); for(/*no-op*/; iWrite<nSize+nBlk-1; iWrite+=nBlk ){ if( iWrite>=nSize ) iWrite = nSize - 1; nWrite = seekAndWrite(pFile, iWrite, "", 1); if( nWrite!=1 ) return SQLITE_IOERR_WRITE; } #endif } } #if SQLITE_MAX_MMAP_SIZE>0 if( pFile->mmapSizeMax>0 && nByte>pFile->mmapSize ){ int rc; if( pFile->szChunk<=0 ){ if( robust_ftruncate(pFile->h, nByte) ){ storeLastErrno(pFile, errno); return unixLogError(SQLITE_IOERR_TRUNCATE, "ftruncate", pFile->zPath); } } rc = unixMapfile(pFile, nByte); return rc; } #endif return SQLITE_OK; } /* ** If *pArg is initially negative then this is a query. Set *pArg to ** 1 or 0 depending on whether or not bit mask of pFile->ctrlFlags is set. ** ** If *pArg is 0 or 1, then clear or set the mask bit of pFile->ctrlFlags. */ static void unixModeBit(unixFile *pFile, unsigned char mask, int *pArg){ if( *pArg<0 ){ *pArg = (pFile->ctrlFlags & mask)!=0; }else if( (*pArg)==0 ){ pFile->ctrlFlags &= ~mask; }else{ pFile->ctrlFlags |= mask; } } /* Forward declaration */ static int unixGetTempname(int nBuf, char *zBuf); #if !defined(SQLITE_WASI) && !defined(SQLITE_OMIT_WAL) static int unixFcntlExternalReader(unixFile*, int*); #endif #if defined(SQLITE_DEBUG) || defined(SQLITE_ENABLE_FILESTAT) static void unixDescribeShm(sqlite3_str*,unixShm*); #endif /* ** Information and control of an open file handle. */ static int unixFileControl(sqlite3_file *id, int op, void *pArg){ unixFile *pFile = (unixFile*)id; switch( op ){ #if defined(__linux__) && defined(SQLITE_ENABLE_BATCH_ATOMIC_WRITE) case SQLITE_FCNTL_BEGIN_ATOMIC_WRITE: { int rc = osIoctl(pFile->h, F2FS_IOC_START_ATOMIC_WRITE); return rc ? SQLITE_IOERR_BEGIN_ATOMIC : SQLITE_OK; } case SQLITE_FCNTL_COMMIT_ATOMIC_WRITE: { int rc = osIoctl(pFile->h, F2FS_IOC_COMMIT_ATOMIC_WRITE); return rc ? SQLITE_IOERR_COMMIT_ATOMIC : SQLITE_OK; } case SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE: { int rc = osIoctl(pFile->h, F2FS_IOC_ABORT_VOLATILE_WRITE); return rc ? SQLITE_IOERR_ROLLBACK_ATOMIC : SQLITE_OK; } #endif /* __linux__ && SQLITE_ENABLE_BATCH_ATOMIC_WRITE */ case SQLITE_FCNTL_NULL_IO: { osClose(pFile->h); pFile->h = -1; return SQLITE_OK; } case SQLITE_FCNTL_LOCKSTATE: { *(int*)pArg = pFile->eFileLock; return SQLITE_OK; } case SQLITE_FCNTL_LAST_ERRNO: { *(int*)pArg = pFile->lastErrno; return SQLITE_OK; } case SQLITE_FCNTL_CHUNK_SIZE: { pFile->szChunk = *(int *)pArg; return SQLITE_OK; } case SQLITE_FCNTL_SIZE_HINT: { int rc; SimulateIOErrorBenign(1); rc = fcntlSizeHint(pFile, *(i64 *)pArg); SimulateIOErrorBenign(0); return rc; } case SQLITE_FCNTL_PERSIST_WAL: { unixModeBit(pFile, UNIXFILE_PERSIST_WAL, (int*)pArg); return SQLITE_OK; } case SQLITE_FCNTL_POWERSAFE_OVERWRITE: { unixModeBit(pFile, UNIXFILE_PSOW, (int*)pArg); return SQLITE_OK; } case SQLITE_FCNTL_VFSNAME: { *(char**)pArg = sqlite3_mprintf("%s", pFile->pVfs->zName); return SQLITE_OK; } case SQLITE_FCNTL_TEMPFILENAME: { char *zTFile = sqlite3_malloc64( pFile->pVfs->mxPathname ); if( zTFile ){ unixGetTempname(pFile->pVfs->mxPathname, zTFile); *(char**)pArg = zTFile; } return SQLITE_OK; } case SQLITE_FCNTL_HAS_MOVED: { *(int*)pArg = fileHasMoved(pFile); return SQLITE_OK; } #ifdef SQLITE_ENABLE_SETLK_TIMEOUT case SQLITE_FCNTL_LOCK_TIMEOUT: { int iOld = pFile->iBusyTimeout; int iNew = *(int*)pArg; #if SQLITE_ENABLE_SETLK_TIMEOUT==1 pFile->iBusyTimeout = iNew<0 ? 0x7FFFFFFF : (unsigned)iNew; #elif SQLITE_ENABLE_SETLK_TIMEOUT==2 pFile->iBusyTimeout = !!(*(int*)pArg); #else # error "SQLITE_ENABLE_SETLK_TIMEOUT must be set to 1 or 2" #endif *(int*)pArg = iOld; return SQLITE_OK; } case SQLITE_FCNTL_BLOCK_ON_CONNECT: { int iNew = *(int*)pArg; pFile->bBlockOnConnect = iNew; return SQLITE_OK; } #endif /* SQLITE_ENABLE_SETLK_TIMEOUT */ #if SQLITE_MAX_MMAP_SIZE>0 case SQLITE_FCNTL_MMAP_SIZE: { i64 newLimit = *(i64*)pArg; int rc = SQLITE_OK; if( newLimit>sqlite3GlobalConfig.mxMmap ){ newLimit = sqlite3GlobalConfig.mxMmap; } /* The value of newLimit may be eventually cast to (size_t) and passed ** to mmap(). Restrict its value to 2GB if (size_t) is not at least a ** 64-bit type. */ if( newLimit>0 && sizeof(size_t)<8 ){ newLimit = (newLimit & 0x7FFFFFFF); } *(i64*)pArg = pFile->mmapSizeMax; if( newLimit>=0 && newLimit!=pFile->mmapSizeMax && pFile->nFetchOut==0 ){ pFile->mmapSizeMax = newLimit; if( pFile->mmapSize>0 ){ unixUnmapfile(pFile); rc = unixMapfile(pFile, -1); } } return rc; } #endif #ifdef SQLITE_DEBUG /* The pager calls this method to signal that it has done ** a rollback and that the database is therefore unchanged and ** it hence it is OK for the transaction change counter to be ** unchanged. */ case SQLITE_FCNTL_DB_UNCHANGED: { ((unixFile*)id)->dbUpdate = 0; return SQLITE_OK; } #endif #if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__) case SQLITE_FCNTL_SET_LOCKPROXYFILE: case SQLITE_FCNTL_GET_LOCKPROXYFILE: { return proxyFileControl(id,op,pArg); } #endif /* SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__) */ case SQLITE_FCNTL_EXTERNAL_READER: { #if !defined(SQLITE_WASI) && !defined(SQLITE_OMIT_WAL) return unixFcntlExternalReader((unixFile*)id, (int*)pArg); #else *(int*)pArg = 0; return SQLITE_OK; #endif } #if defined(SQLITE_DEBUG) || defined(SQLITE_ENABLE_FILESTAT) case SQLITE_FCNTL_FILESTAT: { sqlite3_str *pStr = (sqlite3_str*)pArg; char aLck[16]; unixInodeInfo *pInode; static const char *azLock[] = { "SHARED", "RESERVED", "PENDING", "EXCLUSIVE" }; sqlite3_str_appendf(pStr, "{\"h\":%d", pFile->h); sqlite3_str_appendf(pStr, ",\"vfs\":\"%s\"", pFile->pVfs->zName); if( pFile->eFileLock ){ sqlite3_str_appendf(pStr, ",\"eFileLock\":\"%s\"", azLock[pFile->eFileLock-1]); if( unixPosixAdvisoryLocks(pFile->h, aLck)==SQLITE_OK ){ sqlite3_str_appendf(pStr, ",\"pal\":\"%s\"", aLck); } } unixEnterMutex(); if( pFile->pShm ){ sqlite3_str_appendall(pStr, ",\"shm\":"); unixDescribeShm(pStr, pFile->pShm); } #if SQLITE_MAX_MMAP_SIZE>0 if( pFile->mmapSize ){ sqlite3_str_appendf(pStr, ",\"mmapSize\":%lld", pFile->mmapSize); sqlite3_str_appendf(pStr, ",\"nFetchOut\":%d", pFile->nFetchOut); } #endif if( (pInode = pFile->pInode)!=0 ){ sqlite3_str_appendf(pStr, ",\"inode\":{\"nRef\":%d",pInode->nRef); sqlite3_mutex_enter(pInode->pLockMutex); sqlite3_str_appendf(pStr, ",\"nShared\":%d", pInode->nShared); if( pInode->eFileLock ){ sqlite3_str_appendf(pStr, ",\"eFileLock\":\"%s\"", azLock[pInode->eFileLock-1]); } if( pInode->pUnused ){ char cSep = '['; UnixUnusedFd *pUFd = pFile->pInode->pUnused; sqlite3_str_appendall(pStr, ",\"unusedFd\":"); while( pUFd ){ sqlite3_str_appendf(pStr, "%c{\"fd\":%d,\"flags\":%d", cSep, pUFd->fd, pUFd->flags); cSep = ','; if( unixPosixAdvisoryLocks(pUFd->fd, aLck)==SQLITE_OK ){ sqlite3_str_appendf(pStr, ",\"pal\":\"%s\"", aLck); } sqlite3_str_append(pStr, "}", 1); pUFd = pUFd->pNext; } sqlite3_str_append(pStr, "]", 1); } sqlite3_mutex_leave(pInode->pLockMutex); sqlite3_str_append(pStr, "}", 1); } unixLeaveMutex(); sqlite3_str_append(pStr, "}", 1); return SQLITE_OK; } #endif /* SQLITE_DEBUG || SQLITE_ENABLE_FILESTAT */ } return SQLITE_NOTFOUND; } /* ** If pFd->sectorSize is non-zero when this function is called, it is a ** no-op. Otherwise, the values of pFd->sectorSize and ** pFd->deviceCharacteristics are set according to the file-system ** characteristics. ** ** There are two versions of this function. One for QNX and one for all ** other systems. */ #ifndef __QNXNTO__ static void setDeviceCharacteristics(unixFile *pFd){ assert( pFd->deviceCharacteristics==0 || pFd->sectorSize!=0 ); if( pFd->sectorSize==0 ){ #if defined(__linux__) && defined(SQLITE_ENABLE_BATCH_ATOMIC_WRITE) int res; u32 f = 0; /* Check for support for F2FS atomic batch writes. */ res = osIoctl(pFd->h, F2FS_IOC_GET_FEATURES, &f); if( res==0 && (f & F2FS_FEATURE_ATOMIC_WRITE) ){ pFd->deviceCharacteristics = SQLITE_IOCAP_BATCH_ATOMIC; } #endif /* __linux__ && SQLITE_ENABLE_BATCH_ATOMIC_WRITE */ /* Set the POWERSAFE_OVERWRITE flag if requested. */ if( pFd->ctrlFlags & UNIXFILE_PSOW ){ pFd->deviceCharacteristics |= SQLITE_IOCAP_POWERSAFE_OVERWRITE; } pFd->deviceCharacteristics |= SQLITE_IOCAP_SUBPAGE_READ; pFd->sectorSize = SQLITE_DEFAULT_SECTOR_SIZE; } } #else #include <sys/dcmd_blk.h> #include <sys/statvfs.h> static void setDeviceCharacteristics(unixFile *pFile){ if( pFile->sectorSize == 0 ){ struct statvfs fsInfo; /* Set defaults for non-supported filesystems */ pFile->sectorSize = SQLITE_DEFAULT_SECTOR_SIZE; pFile->deviceCharacteristics = 0; if( fstatvfs(pFile->h, &fsInfo) == -1 ) { return; } if( !strcmp(fsInfo.f_basetype, "tmp") ) { pFile->sectorSize = fsInfo.f_bsize; pFile->deviceCharacteristics = SQLITE_IOCAP_ATOMIC4K | /* All ram filesystem writes are atomic */ SQLITE_IOCAP_SAFE_APPEND | /* growing the file does not occur until ** the write succeeds */ SQLITE_IOCAP_SEQUENTIAL | /* The ram filesystem has no write behind ** so it is ordered */ 0; }else if( strstr(fsInfo.f_basetype, "etfs") ){ pFile->sectorSize = fsInfo.f_bsize; pFile->deviceCharacteristics = /* etfs cluster size writes are atomic */ (pFile->sectorSize / 512 * SQLITE_IOCAP_ATOMIC512) | SQLITE_IOCAP_SAFE_APPEND | /* growing the file does not occur until ** the write succeeds */ SQLITE_IOCAP_SEQUENTIAL | /* The ram filesystem has no write behind ** so it is ordered */ 0; }else if( !strcmp(fsInfo.f_basetype, "qnx6") ){ pFile->sectorSize = fsInfo.f_bsize; pFile->deviceCharacteristics = SQLITE_IOCAP_ATOMIC | /* All filesystem writes are atomic */ SQLITE_IOCAP_SAFE_APPEND | /* growing the file does not occur until ** the write succeeds */ SQLITE_IOCAP_SEQUENTIAL | /* The ram filesystem has no write behind ** so it is ordered */ 0; }else if( !strcmp(fsInfo.f_basetype, "qnx4") ){ pFile->sectorSize = fsInfo.f_bsize; pFile->deviceCharacteristics = /* full bitset of atomics from max sector size and smaller */ (((pFile->sectorSize / 512 * SQLITE_IOCAP_ATOMIC512) << 1) - 2) | SQLITE_IOCAP_SEQUENTIAL | /* The ram filesystem has no write behind ** so it is ordered */ 0; }else if( strstr(fsInfo.f_basetype, "dos") ){ pFile->sectorSize = fsInfo.f_bsize; pFile->deviceCharacteristics = /* full bitset of atomics from max sector size and smaller */ (((pFile->sectorSize / 512 * SQLITE_IOCAP_ATOMIC512) << 1) - 2) | SQLITE_IOCAP_SEQUENTIAL | /* The ram filesystem has no write behind ** so it is ordered */ 0; }else{ pFile->deviceCharacteristics = SQLITE_IOCAP_ATOMIC512 | /* blocks are atomic */ SQLITE_IOCAP_SAFE_APPEND | /* growing the file does not occur until ** the write succeeds */ 0; } } /* Last chance verification. If the sector size isn't a multiple of 512 ** then it isn't valid.*/ if( pFile->sectorSize % 512 != 0 ){ pFile->deviceCharacteristics = 0; pFile->sectorSize = SQLITE_DEFAULT_SECTOR_SIZE; } } #endif /* ** Return the sector size in bytes of the underlying block device for ** the specified file. This is almost always 512 bytes, but may be ** larger for some devices. ** ** SQLite code assumes this function cannot fail. It also assumes that ** if two files are created in the same file-system directory (i.e. ** a database and its journal file) that the sector size will be the ** same for both. */ static int unixSectorSize(sqlite3_file *id){ unixFile *pFd = (unixFile*)id; setDeviceCharacteristics(pFd); return pFd->sectorSize; } /* ** Return the device characteristics for the file. ** ** This VFS is set up to return SQLITE_IOCAP_POWERSAFE_OVERWRITE by default. ** However, that choice is controversial since technically the underlying ** file system does not always provide powersafe overwrites. (In other ** words, after a power-loss event, parts of the file that were never ** written might end up being altered.) However, non-PSOW behavior is very, ** very rare. And asserting PSOW makes a large reduction in the amount ** of required I/O for journaling, since a lot of padding is eliminated. ** Hence, while POWERSAFE_OVERWRITE is on by default, there is a file-control ** available to turn it off and URI query parameter available to turn it off. */ static int unixDeviceCharacteristics(sqlite3_file *id){ unixFile *pFd = (unixFile*)id; setDeviceCharacteristics(pFd); return pFd->deviceCharacteristics; } #if !defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0 /* ** Return the system page size. ** ** This function should not be called directly by other code in this file. ** Instead, it should be called via macro osGetpagesize(). */ static int unixGetpagesize(void){ #if OS_VXWORKS return 1024; #elif defined(_BSD_SOURCE) return getpagesize(); #else return (int)sysconf(_SC_PAGESIZE); #endif } #endif /* !defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0 */ #if !defined(SQLITE_WASI) && !defined(SQLITE_OMIT_WAL) /* ** Object used to represent an shared memory buffer. ** ** When multiple threads all reference the same wal-index, each thread ** has its own unixShm object, but they all point to a single instance ** of this unixShmNode object. In other words, each wal-index is opened ** only once per process. ** ** Each unixShmNode object is connected to a single unixInodeInfo object. ** We could coalesce this object into unixInodeInfo, but that would mean ** every open file that does not use shared memory (in other words, most ** open files) would have to carry around this extra information. So ** the unixInodeInfo object contains a pointer to this unixShmNode object ** and the unixShmNode object is created only when needed. ** ** unixMutexHeld() must be true when creating or destroying ** this object or while reading or writing the following fields: ** ** nRef ** ** The following fields are read-only after the object is created: ** ** hShm ** zFilename ** ** Either unixShmNode.pShmMutex must be held or unixShmNode.nRef==0 and ** unixMutexHeld() is true when reading or writing any other field ** in this structure. ** ** aLock[SQLITE_SHM_NLOCK]: ** This array records the various locks held by clients on each of the ** SQLITE_SHM_NLOCK slots. If the aLock[] entry is set to 0, then no ** locks are held by the process on this slot. If it is set to -1, then ** some client holds an EXCLUSIVE lock on the locking slot. If the aLock[] ** value is set to a positive value, then it is the number of shared ** locks currently held on the slot. ** ** aMutex[SQLITE_SHM_NLOCK]: ** Normally, when SQLITE_ENABLE_SETLK_TIMEOUT is not defined, mutex ** pShmMutex is used to protect the aLock[] array and the right to ** call fcntl() on unixShmNode.hShm to obtain or release locks. ** ** If SQLITE_ENABLE_SETLK_TIMEOUT is defined though, we use an array ** of mutexes - one for each locking slot. To read or write locking ** slot aLock[iSlot], the caller must hold the corresponding mutex ** aMutex[iSlot]. Similarly, to call fcntl() to obtain or release a ** lock corresponding to slot iSlot, mutex aMutex[iSlot] must be held. */ struct unixShmNode { unixInodeInfo *pInode; /* unixInodeInfo that owns this SHM node */ sqlite3_mutex *pShmMutex; /* Mutex to access this object */ char *zFilename; /* Name of the mmapped file */ int hShm; /* Open file descriptor */ int szRegion; /* Size of shared-memory regions */ u16 nRegion; /* Size of array apRegion */ u8 isReadonly; /* True if read-only */ u8 isUnlocked; /* True if no DMS lock held */ char **apRegion; /* Array of mapped shared-memory regions */ int nRef; /* Number of unixShm objects pointing to this */ unixShm *pFirst; /* All unixShm objects pointing to this */ #ifdef SQLITE_ENABLE_SETLK_TIMEOUT sqlite3_mutex *aMutex[SQLITE_SHM_NLOCK]; #endif int aLock[SQLITE_SHM_NLOCK]; /* # shared locks on slot, -1==excl lock */ #ifdef SQLITE_DEBUG u8 nextShmId; /* Next available unixShm.id value */ #endif }; /* ** Structure used internally by this VFS to record the state of an ** open shared memory connection. ** ** The following fields are initialized when this object is created and ** are read-only thereafter: ** ** unixShm.pShmNode ** unixShm.id ** ** All other fields are read/write. The unixShm.pShmNode->pShmMutex must ** be held while accessing any read/write fields. */ struct unixShm { unixShmNode *pShmNode; /* The underlying unixShmNode object */ unixShm *pNext; /* Next unixShm with the same unixShmNode */ u8 hasMutex; /* True if holding the unixShmNode->pShmMutex */ u8 id; /* Id of this connection within its unixShmNode */ u16 sharedMask; /* Mask of shared locks held */ u16 exclMask; /* Mask of exclusive locks held */ }; /* ** Constants used for locking */ #define UNIX_SHM_BASE ((22+SQLITE_SHM_NLOCK)*4) /* first lock byte */ #define UNIX_SHM_DMS (UNIX_SHM_BASE+SQLITE_SHM_NLOCK) /* deadman switch */ #if defined(SQLITE_DEBUG) || defined(SQLITE_ENABLE_FILESTAT) /* ** Describe the pShm object using JSON. Used for diagnostics only. */ static void unixDescribeShm(sqlite3_str *pStr, unixShm *pShm){ unixShmNode *pNode = pShm->pShmNode; char aLck[16]; sqlite3_str_appendf(pStr, "{\"h\":%d", pNode->hShm); assert( unixMutexHeld() ); sqlite3_str_appendf(pStr, ",\"nRef\":%d", pNode->nRef); sqlite3_str_appendf(pStr, ",\"id\":%d", pShm->id); sqlite3_str_appendf(pStr, ",\"sharedMask\":%d", pShm->sharedMask); sqlite3_str_appendf(pStr, ",\"exclMask\":%d", pShm->exclMask); if( unixPosixAdvisoryLocks(pNode->hShm, aLck)==SQLITE_OK ){ sqlite3_str_appendf(pStr, ",\"pal\":\"%s\"", aLck); } sqlite3_str_append(pStr, "}", 1); } #endif /* SQLITE_DEBUG || SQLITE_ENABLE_FILESTAT */ /* ** Use F_GETLK to check whether or not there are any readers with open ** wal-mode transactions in other processes on database file pFile. If ** no error occurs, return SQLITE_OK and set (*piOut) to 1 if there are ** such transactions, or 0 otherwise. If an error occurs, return an ** SQLite error code. The final value of *piOut is undefined in this ** case. */ static int unixFcntlExternalReader(unixFile *pFile, int *piOut){ int rc = SQLITE_OK; *piOut = 0; if( pFile->pShm){ unixShmNode *pShmNode = pFile->pShm->pShmNode; struct flock f; memset(&f, 0, sizeof(f)); f.l_type = F_WRLCK; f.l_whence = SEEK_SET; f.l_start = UNIX_SHM_BASE + 3; f.l_len = SQLITE_SHM_NLOCK - 3; sqlite3_mutex_enter(pShmNode->pShmMutex); if( osFcntl(pShmNode->hShm, F_GETLK, &f)<0 ){ rc = SQLITE_IOERR_LOCK; }else{ *piOut = (f.l_type!=F_UNLCK); } sqlite3_mutex_leave(pShmNode->pShmMutex); } return rc; } /* ** If pFile has a -shm file open and it is sharing that file with some ** other connection, either in the same process or in a separate process, ** then return true. Return false if either pFile does not have a -shm ** file open or if it is the only connection to that -shm file across the ** entire system. ** ** This routine is not required for correct operation. It can always return ** false and SQLite will continue to operate according to spec. However, ** when this routine does its job, it adds extra robustness in cases ** where database file locks have been erroneously deleted in a WAL-mode ** database by doing close(open(DATABASE_PATHNAME)) or similar. ** ** With false negatives, SQLite still operates to spec, though with less ** robustness. With false positives, the last database connection on a ** WAL-mode database will fail to unlink the -wal and -shm files, which ** is annoying but harmless. False positives will also prevent a database ** connection from running "PRAGMA journal_mode=DELETE" in order to take ** the database out of WAL mode, which is perhaps more serious, but is ** still not a disaster. */ static int unixIsSharingShmNode(unixFile *pFile){ unixShmNode *pShmNode; struct flock lock; if( pFile->pShm==0 ) return 0; if( pFile->ctrlFlags & UNIXFILE_EXCL ) return 0; pShmNode = pFile->pShm->pShmNode; #if SQLITE_ATOMIC_INTRINSICS assert( AtomicLoad(&pShmNode->nRef)==1 ); #endif memset(&lock, 0, sizeof(lock)); lock.l_whence = SEEK_SET; lock.l_start = UNIX_SHM_DMS; lock.l_len = 1; lock.l_type = F_WRLCK; osFcntl(pShmNode->hShm, F_GETLK, &lock); return (lock.l_type!=F_UNLCK); } /* ** Apply posix advisory locks for all bytes from ofst through ofst+n-1. ** ** Locks block if the mask is exactly UNIX_SHM_C and are non-blocking ** otherwise. */ static int unixShmSystemLock( unixFile *pFile, /* Open connection to the WAL file */ int lockType, /* F_UNLCK, F_RDLCK, or F_WRLCK */ int ofst, /* First byte of the locking range */ int n /* Number of bytes to lock */ ){ unixShmNode *pShmNode; /* Apply locks to this open shared-memory segment */ struct flock f; /* The posix advisory locking structure */ int rc = SQLITE_OK; /* Result code form fcntl() */ pShmNode = pFile->pInode->pShmNode; /* Assert that the parameters are within expected range and that the ** correct mutex or mutexes are held. */ assert( pShmNode->nRef>=0 ); assert( (ofst==UNIX_SHM_DMS && n==1) || (ofst>=UNIX_SHM_BASE && ofst+n<=(UNIX_SHM_BASE+SQLITE_SHM_NLOCK)) ); if( ofst==UNIX_SHM_DMS ){ assert( pShmNode->nRef>0 || unixMutexHeld() ); assert( pShmNode->nRef==0 || sqlite3_mutex_held(pShmNode->pShmMutex) ); }else{ #ifdef SQLITE_ENABLE_SETLK_TIMEOUT int ii; for(ii=ofst-UNIX_SHM_BASE; ii<ofst-UNIX_SHM_BASE+n; ii++){ assert( sqlite3_mutex_held(pShmNode->aMutex[ii]) ); } #else assert( sqlite3_mutex_held(pShmNode->pShmMutex) ); assert( pShmNode->nRef>0 ); #endif } /* Shared locks never span more than one byte */ assert( n==1 || lockType!=F_RDLCK ); /* Locks are within range */ assert( n>=1 && n<=SQLITE_SHM_NLOCK ); assert( ofst>=UNIX_SHM_BASE && ofst<=UNIX_SHM_DMS ); assert( ofst+n-1<=UNIX_SHM_DMS ); if( pShmNode->hShm>=0 ){ int res; /* Initialize the locking parameters */ f.l_type = lockType; f.l_whence = SEEK_SET; f.l_start = ofst; f.l_len = n; res = osSetPosixAdvisoryLock(pShmNode->hShm, &f, pFile); if( res==-1 ){ #if defined(SQLITE_ENABLE_SETLK_TIMEOUT) && SQLITE_ENABLE_SETLK_TIMEOUT==1 rc = (pFile->iBusyTimeout ? SQLITE_BUSY_TIMEOUT : SQLITE_BUSY); #else rc = SQLITE_BUSY; #endif } } /* Do debug tracing */ #ifdef SQLITE_DEBUG OSTRACE(("SHM-LOCK ")); if( rc==SQLITE_OK ){ if( lockType==F_UNLCK ){ OSTRACE(("unlock %d..%d ok\n", ofst, ofst+n-1)); }else if( lockType==F_RDLCK ){ OSTRACE(("read-lock %d..%d ok\n", ofst, ofst+n-1)); }else{ assert( lockType==F_WRLCK ); OSTRACE(("write-lock %d..%d ok\n", ofst, ofst+n-1)); } }else{ if( lockType==F_UNLCK ){ OSTRACE(("unlock %d..%d failed\n", ofst, ofst+n-1)); }else if( lockType==F_RDLCK ){ OSTRACE(("read-lock %d..%d failed\n", ofst, ofst+n-1)); }else{ assert( lockType==F_WRLCK ); OSTRACE(("write-lock %d..%d failed\n", ofst, ofst+n-1)); } } #endif return rc; } /* ** Return the minimum number of 32KB shm regions that should be mapped at ** a time, assuming that each mapping must be an integer multiple of the ** current system page-size. ** ** Usually, this is 1. The exception seems to be systems that are configured ** to use 64KB pages - in this case each mapping must cover at least two ** shm regions. */ static int unixShmRegionPerMap(void){ int shmsz = 32*1024; /* SHM region size */ int pgsz = osGetpagesize(); /* System page size */ assert( ((pgsz-1)&pgsz)==0 ); /* Page size must be a power of 2 */ if( pgsz<shmsz ) return 1; return pgsz/shmsz; } /* ** Purge the unixShmNodeList list of all entries with unixShmNode.nRef==0. ** ** This is not a VFS shared-memory method; it is a utility function called ** by VFS shared-memory methods. */ static void unixShmPurge(unixFile *pFd){ unixShmNode *p = pFd->pInode->pShmNode; assert( unixMutexHeld() ); if( p && ALWAYS(p->nRef==0) ){ int nShmPerMap = unixShmRegionPerMap(); int i; assert( p->pInode==pFd->pInode ); sqlite3_mutex_free(p->pShmMutex); #ifdef SQLITE_ENABLE_SETLK_TIMEOUT for(i=0; i<SQLITE_SHM_NLOCK; i++){ sqlite3_mutex_free(p->aMutex[i]); } #endif for(i=0; i<p->nRegion; i+=nShmPerMap){ if( p->hShm>=0 ){ osMunmap(p->apRegion[i], p->szRegion); }else{ sqlite3_free(p->apRegion[i]); } } sqlite3_free(p->apRegion); if( p->hShm>=0 ){ robust_close(pFd, p->hShm, __LINE__); p->hShm = -1; } p->pInode->pShmNode = 0; sqlite3_free(p); } } /* ** The DMS lock has not yet been taken on shm file pShmNode. Attempt to ** take it now. Return SQLITE_OK if successful, or an SQLite error ** code otherwise. ** ** If the DMS cannot be locked because this is a readonly_shm=1 ** connection and no other process already holds a lock, return ** SQLITE_READONLY_CANTINIT and set pShmNode->isUnlocked=1. */ static int unixLockSharedMemory(unixFile *pDbFd, unixShmNode *pShmNode){ struct flock lock; int rc = SQLITE_OK; /* Use F_GETLK to determine the locks other processes are holding ** on the DMS byte. If it indicates that another process is holding ** a SHARED lock, then this process may also take a SHARED lock ** and proceed with opening the *-shm file. ** ** Or, if no other process is holding any lock, then this process ** is the first to open it. In this case take an EXCLUSIVE lock on the ** DMS byte and truncate the *-shm file to zero bytes in size. Then ** downgrade to a SHARED lock on the DMS byte. ** ** If another process is holding an EXCLUSIVE lock on the DMS byte, ** return SQLITE_BUSY to the caller (it will try again). An earlier ** version of this code attempted the SHARED lock at this point. But ** this introduced a subtle race condition: if the process holding ** EXCLUSIVE failed just before truncating the *-shm file, then this ** process might open and use the *-shm file without truncating it. ** And if the *-shm file has been corrupted by a power failure or ** system crash, the database itself may also become corrupt. */ lock.l_whence = SEEK_SET; lock.l_start = UNIX_SHM_DMS; lock.l_len = 1; lock.l_type = F_WRLCK; if( osFcntl(pShmNode->hShm, F_GETLK, &lock)!=0 ) { rc = SQLITE_IOERR_LOCK; }else if( lock.l_type==F_UNLCK ){ if( pShmNode->isReadonly ){ pShmNode->isUnlocked = 1; rc = SQLITE_READONLY_CANTINIT; }else{ #ifdef SQLITE_ENABLE_SETLK_TIMEOUT /* Do not use a blocking lock here. If the lock cannot be obtained ** immediately, it means some other connection is truncating the ** *-shm file. And after it has done so, it will not release its ** lock, but only downgrade it to a shared lock. So no point in ** blocking here. The call below to obtain the shared DMS lock may ** use a blocking lock. */ int iSaveTimeout = pDbFd->iBusyTimeout; pDbFd->iBusyTimeout = 0; #endif rc = unixShmSystemLock(pDbFd, F_WRLCK, UNIX_SHM_DMS, 1); #ifdef SQLITE_ENABLE_SETLK_TIMEOUT pDbFd->iBusyTimeout = iSaveTimeout; #endif /* The first connection to attach must truncate the -shm file. We ** truncate to 3 bytes (an arbitrary small number, less than the ** -shm header size) rather than 0 as a system debugging aid, to ** help detect if a -shm file truncation is legitimate or is the work ** or a rogue process. */ if( rc==SQLITE_OK && robust_ftruncate(pShmNode->hShm, 3) ){ rc = unixLogError(SQLITE_IOERR_SHMOPEN,"ftruncate",pShmNode->zFilename); } } }else if( lock.l_type==F_WRLCK ){ rc = SQLITE_BUSY; } if( rc==SQLITE_OK ){ assert( lock.l_type==F_UNLCK || lock.l_type==F_RDLCK ); rc = unixShmSystemLock(pDbFd, F_RDLCK, UNIX_SHM_DMS, 1); } return rc; } /* ** Open a shared-memory area associated with open database file pDbFd. ** This particular implementation uses mmapped files. ** ** The file used to implement shared-memory is in the same directory ** as the open database file and has the same name as the open database ** file with the "-shm" suffix added. For example, if the database file ** is "/home/user1/config.db" then the file that is created and mmapped ** for shared memory will be called "/home/user1/config.db-shm". ** ** Another approach to is to use files in /dev/shm or /dev/tmp or an ** some other tmpfs mount. But if a file in a different directory ** from the database file is used, then differing access permissions ** or a chroot() might cause two different processes on the same ** database to end up using different files for shared memory - ** meaning that their memory would not really be shared - resulting ** in database corruption. Nevertheless, this tmpfs file usage ** can be enabled at compile-time using -DSQLITE_SHM_DIRECTORY="/dev/shm" ** or the equivalent. The use of the SQLITE_SHM_DIRECTORY compile-time ** option results in an incompatible build of SQLite; builds of SQLite ** that with differing SQLITE_SHM_DIRECTORY settings attempt to use the ** same database file at the same time, database corruption will likely ** result. The SQLITE_SHM_DIRECTORY compile-time option is considered ** "unsupported" and may go away in a future SQLite release. ** ** When opening a new shared-memory file, if no other instances of that ** file are currently open, in this process or in other processes, then ** the file must be truncated to zero length or have its header cleared. ** ** If the original database file (pDbFd) is using the "unix-excl" VFS ** that means that an exclusive lock is held on the database file and ** that no other processes are able to read or write the database. In ** that case, we do not really need shared memory. No shared memory ** file is created. The shared memory will be simulated with heap memory. */ static int unixOpenSharedMemory(unixFile *pDbFd){ struct unixShm *p = 0; /* The connection to be opened */ struct unixShmNode *pShmNode; /* The underlying mmapped file */ int rc = SQLITE_OK; /* Result code */ unixInodeInfo *pInode; /* The inode of fd */ char *zShm; /* Name of the file used for SHM */ int nShmFilename; /* Size of the SHM filename in bytes */ /* Allocate space for the new unixShm object. */ p = sqlite3_malloc64( sizeof(*p) ); if( p==0 ) return SQLITE_NOMEM_BKPT; memset(p, 0, sizeof(*p)); assert( pDbFd->pShm==0 ); /* Check to see if a unixShmNode object already exists. Reuse an existing ** one if present. Create a new one if necessary. */ assert( unixFileMutexNotheld(pDbFd) ); unixEnterMutex(); pInode = pDbFd->pInode; pShmNode = pInode->pShmNode; if( pShmNode==0 ){ struct stat sStat; /* fstat() info for database file */ #ifndef SQLITE_SHM_DIRECTORY const char *zBasePath = pDbFd->zPath; #endif /* Call fstat() to figure out the permissions on the database file. If ** a new *-shm file is created, an attempt will be made to create it ** with the same permissions. */ if( osFstat(pDbFd->h, &sStat) ){ rc = SQLITE_IOERR_FSTAT; goto shm_open_err; } #ifdef SQLITE_SHM_DIRECTORY nShmFilename = sizeof(SQLITE_SHM_DIRECTORY) + 31; #else nShmFilename = 6 + (int)strlen(zBasePath); #endif pShmNode = sqlite3_malloc64( sizeof(*pShmNode) + nShmFilename ); if( pShmNode==0 ){ rc = SQLITE_NOMEM_BKPT; goto shm_open_err; } memset(pShmNode, 0, sizeof(*pShmNode)+nShmFilename); zShm = pShmNode->zFilename = (char*)&pShmNode[1]; #ifdef SQLITE_SHM_DIRECTORY sqlite3_snprintf(nShmFilename, zShm, SQLITE_SHM_DIRECTORY "/sqlite-shm-%x-%x", (u32)sStat.st_ino, (u32)sStat.st_dev); #else sqlite3_snprintf(nShmFilename, zShm, "%s-shm", zBasePath); sqlite3FileSuffix3(pDbFd->zPath, zShm); #endif pShmNode->hShm = -1; pDbFd->pInode->pShmNode = pShmNode; pShmNode->pInode = pDbFd->pInode; if( sqlite3GlobalConfig.bCoreMutex ){ pShmNode->pShmMutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST); if( pShmNode->pShmMutex==0 ){ rc = SQLITE_NOMEM_BKPT; goto shm_open_err; } #ifdef SQLITE_ENABLE_SETLK_TIMEOUT { int ii; for(ii=0; ii<SQLITE_SHM_NLOCK; ii++){ pShmNode->aMutex[ii] = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST); if( pShmNode->aMutex[ii]==0 ){ rc = SQLITE_NOMEM_BKPT; goto shm_open_err; } } } #endif } if( pInode->bProcessLock==0 ){ if( 0==sqlite3_uri_boolean(pDbFd->zPath, "readonly_shm", 0) ){ pShmNode->hShm = robust_open(zShm, O_RDWR|O_CREAT|O_NOFOLLOW, (sStat.st_mode&0777)); } if( pShmNode->hShm<0 ){ pShmNode->hShm = robust_open(zShm, O_RDONLY|O_NOFOLLOW, (sStat.st_mode&0777)); if( pShmNode->hShm<0 ){ rc = unixLogError(SQLITE_CANTOPEN_BKPT, "open", zShm); goto shm_open_err; } pShmNode->isReadonly = 1; } /* If this process is running as root, make sure that the SHM file ** is owned by the same user that owns the original database. Otherwise, ** the original owner will not be able to connect. */ robustFchown(pShmNode->hShm, sStat.st_uid, sStat.st_gid); rc = unixLockSharedMemory(pDbFd, pShmNode); if( rc!=SQLITE_OK && rc!=SQLITE_READONLY_CANTINIT ) goto shm_open_err; } } /* Make the new connection a child of the unixShmNode */ p->pShmNode = pShmNode; #ifdef SQLITE_DEBUG p->id = pShmNode->nextShmId++; #endif pShmNode->nRef++; pDbFd->pShm = p; unixLeaveMutex(); /* The reference count on pShmNode has already been incremented under ** the cover of the unixEnterMutex() mutex and the pointer from the ** new (struct unixShm) object to the pShmNode has been set. All that is ** left to do is to link the new object into the linked list starting ** at pShmNode->pFirst. This must be done while holding the ** pShmNode->pShmMutex. */ sqlite3_mutex_enter(pShmNode->pShmMutex); p->pNext = pShmNode->pFirst; pShmNode->pFirst = p; sqlite3_mutex_leave(pShmNode->pShmMutex); return rc; /* Jump here on any error */ shm_open_err: unixShmPurge(pDbFd); /* This call frees pShmNode if required */ sqlite3_free(p); unixLeaveMutex(); return rc; } /* ** This function is called to obtain a pointer to region iRegion of the ** shared-memory associated with the database file fd. Shared-memory regions ** are numbered starting from zero. Each shared-memory region is szRegion ** bytes in size. ** ** If an error occurs, an error code is returned and *pp is set to NULL. ** ** Otherwise, if the bExtend parameter is 0 and the requested shared-memory ** region has not been allocated (by any client, including one running in a ** separate process), then *pp is set to NULL and SQLITE_OK returned. If ** bExtend is non-zero and the requested shared-memory region has not yet ** been allocated, it is allocated by this function. ** ** If the shared-memory region has already been allocated or is allocated by ** this call as described above, then it is mapped into this processes ** address space (if it is not already), *pp is set to point to the mapped ** memory and SQLITE_OK returned. */ static int unixShmMap( sqlite3_file *fd, /* Handle open on database file */ int iRegion, /* Region to retrieve */ int szRegion, /* Size of regions */ int bExtend, /* True to extend file if necessary */ void volatile **pp /* OUT: Mapped memory */ ){ unixFile *pDbFd = (unixFile*)fd; unixShm *p; unixShmNode *pShmNode; int rc = SQLITE_OK; int nShmPerMap = unixShmRegionPerMap(); int nReqRegion; /* If the shared-memory file has not yet been opened, open it now. */ if( pDbFd->pShm==0 ){ rc = unixOpenSharedMemory(pDbFd); if( rc!=SQLITE_OK ) return rc; } p = pDbFd->pShm; pShmNode = p->pShmNode; sqlite3_mutex_enter(pShmNode->pShmMutex); if( pShmNode->isUnlocked ){ rc = unixLockSharedMemory(pDbFd, pShmNode); if( rc!=SQLITE_OK ) goto shmpage_out; pShmNode->isUnlocked = 0; } assert( szRegion==pShmNode->szRegion || pShmNode->nRegion==0 ); assert( pShmNode->pInode==pDbFd->pInode ); assert( pShmNode->hShm>=0 || pDbFd->pInode->bProcessLock==1 ); assert( pShmNode->hShm<0 || pDbFd->pInode->bProcessLock==0 ); /* Minimum number of regions required to be mapped. */ nReqRegion = ((iRegion+nShmPerMap) / nShmPerMap) * nShmPerMap; if( pShmNode->nRegion<nReqRegion ){ char **apNew; /* New apRegion[] array */ i64 nByte = nReqRegion*(i64)szRegion; /* Minimum required file size */ struct stat sStat; /* Used by fstat() */ pShmNode->szRegion = szRegion; if( pShmNode->hShm>=0 ){ /* The requested region is not mapped into this processes address space. ** Check to see if it has been allocated (i.e. if the wal-index file is ** large enough to contain the requested region). */ if( osFstat(pShmNode->hShm, &sStat) ){ rc = SQLITE_IOERR_SHMSIZE; goto shmpage_out; } if( sStat.st_size<nByte ){ /* The requested memory region does not exist. If bExtend is set to ** false, exit early. *pp will be set to NULL and SQLITE_OK returned. */ if( !bExtend ){ goto shmpage_out; } /* Alternatively, if bExtend is true, extend the file. Do this by ** writing a single byte to the end of each (OS) page being ** allocated or extended. Technically, we need only write to the ** last page in order to extend the file. But writing to all new ** pages forces the OS to allocate them immediately, which reduces ** the chances of SIGBUS while accessing the mapped region later on. */ else{ static const int pgsz = 4096; i64 iPg; /* Write to the last byte of each newly allocated or extended page */ assert( (nByte % pgsz)==0 ); for(iPg=(sStat.st_size/pgsz); iPg<(nByte/pgsz); iPg++){ int x = 0; if( seekAndWriteFd(pShmNode->hShm, iPg*pgsz + pgsz-1,"",1,&x)!=1 ){ const char *zFile = pShmNode->zFilename; rc = unixLogError(SQLITE_IOERR_SHMSIZE, "write", zFile); goto shmpage_out; } } } } } /* Map the requested memory region into this processes address space. */ apNew = (char **)sqlite3_realloc64( pShmNode->apRegion, nReqRegion*sizeof(char *) ); if( !apNew ){ rc = SQLITE_IOERR_NOMEM_BKPT; goto shmpage_out; } pShmNode->apRegion = apNew; while( pShmNode->nRegion<nReqRegion ){ i64 nMap = (i64)szRegion*(i64)nShmPerMap; i64 i; void *pMem; if( pShmNode->hShm>=0 ){ pMem = osMmap(0, nMap, pShmNode->isReadonly ? PROT_READ : PROT_READ|PROT_WRITE, MAP_SHARED, pShmNode->hShm, szRegion*(i64)pShmNode->nRegion ); if( pMem==MAP_FAILED ){ rc = unixLogError(SQLITE_IOERR_SHMMAP, "mmap", pShmNode->zFilename); goto shmpage_out; } }else{ pMem = sqlite3_malloc64(nMap); if( pMem==0 ){ rc = SQLITE_NOMEM_BKPT; goto shmpage_out; } memset(pMem, 0, nMap); } for(i=0; i<nShmPerMap; i++){ pShmNode->apRegion[pShmNode->nRegion+i] = &((char*)pMem)[szRegion*i]; } pShmNode->nRegion += nShmPerMap; } } shmpage_out: if( pShmNode->nRegion>iRegion ){ *pp = pShmNode->apRegion[iRegion]; }else{ *pp = 0; } if( pShmNode->isReadonly && rc==SQLITE_OK ) rc = SQLITE_READONLY; sqlite3_mutex_leave(pShmNode->pShmMutex); return rc; } /* ** Check that the pShmNode->aLock[] array comports with the locking bitmasks ** held by each client. Return true if it does, or false otherwise. This ** is to be used in an assert(). e.g. ** ** assert( assertLockingArrayOk(pShmNode) ); */ #ifdef SQLITE_DEBUG static int assertLockingArrayOk(unixShmNode *pShmNode){ #ifdef SQLITE_ENABLE_SETLK_TIMEOUT return 1; #else unixShm *pX; int aLock[SQLITE_SHM_NLOCK]; memset(aLock, 0, sizeof(aLock)); for(pX=pShmNode->pFirst; pX; pX=pX->pNext){ int i; for(i=0; i<SQLITE_SHM_NLOCK; i++){ if( pX->exclMask & (1<<i) ){ assert( aLock[i]==0 ); aLock[i] = -1; }else if( pX->sharedMask & (1<<i) ){ assert( aLock[i]>=0 ); aLock[i]++; } } } assert( 0==memcmp(pShmNode->aLock, aLock, sizeof(aLock)) ); return (memcmp(pShmNode->aLock, aLock, sizeof(aLock))==0); #endif } #endif /* !defined(SQLITE_WASI) && !defined(SQLITE_OMIT_WAL) */ /* ** Change the lock state for a shared-memory segment. ** ** Note that the relationship between SHARED and EXCLUSIVE locks is a little ** different here than in posix. In xShmLock(), one can go from unlocked ** to shared and back or from unlocked to exclusive and back. But one may ** not go from shared to exclusive or from exclusive to shared. */ static int unixShmLock( sqlite3_file *fd, /* Database file holding the shared memory */ int ofst, /* First lock to acquire or release */ int n, /* Number of locks to acquire or release */ int flags /* What to do with the lock */ ){ unixFile *pDbFd = (unixFile*)fd; /* Connection holding shared memory */ unixShm *p; /* The shared memory being locked */ unixShmNode *pShmNode; /* The underlying file iNode */ int rc = SQLITE_OK; /* Result code */ u16 mask = (1<<(ofst+n)) - (1<<ofst); /* Mask of locks to take or release */ int *aLock; p = pDbFd->pShm; if( p==0 ) return SQLITE_IOERR_SHMLOCK; pShmNode = p->pShmNode; if( NEVER(pShmNode==0) ) return SQLITE_IOERR_SHMLOCK; aLock = pShmNode->aLock; assert( pShmNode==pDbFd->pInode->pShmNode ); assert( pShmNode->pInode==pDbFd->pInode ); assert( ofst>=0 && ofst+n<=SQLITE_SHM_NLOCK ); assert( n>=1 ); assert( flags==(SQLITE_SHM_LOCK | SQLITE_SHM_SHARED) || flags==(SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE) || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED) || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE) ); assert( n==1 || (flags & SQLITE_SHM_EXCLUSIVE)!=0 ); assert( pShmNode->hShm>=0 || pDbFd->pInode->bProcessLock==1 ); assert( pShmNode->hShm<0 || pDbFd->pInode->bProcessLock==0 ); /* Check that, if this to be a blocking lock, no locks that occur later ** in the following list than the lock being obtained are already held: ** ** 1. Recovery lock (ofst==2). ** 2. Checkpointer lock (ofst==1). ** 3. Write lock (ofst==0). ** 4. Read locks (ofst>=3 && ofst<SQLITE_SHM_NLOCK). ** ** In other words, if this is a blocking lock, none of the locks that ** occur later in the above list than the lock being obtained may be ** held. */ #if defined(SQLITE_ENABLE_SETLK_TIMEOUT) && defined(SQLITE_DEBUG) { u16 lockMask = (p->exclMask|p->sharedMask); assert( (flags & SQLITE_SHM_UNLOCK) || pDbFd->iBusyTimeout==0 || ( (ofst!=2 || lockMask==0) && (ofst!=1 || lockMask==0 || lockMask==2) && (ofst!=0 || lockMask<3) && (ofst<3 || lockMask<(1<<ofst)) )); } #endif /* Check if there is any work to do. There are three cases: ** ** a) An unlock operation where there are locks to unlock, ** b) An shared lock where the requested lock is not already held ** c) An exclusive lock where the requested lock is not already held ** ** The SQLite core never requests an exclusive lock that it already holds. ** This is assert()ed below. */ assert( flags!=(SQLITE_SHM_EXCLUSIVE|SQLITE_SHM_LOCK) || 0==(p->exclMask & mask) ); if( ((flags & SQLITE_SHM_UNLOCK) && ((p->exclMask|p->sharedMask) & mask)) || (flags==(SQLITE_SHM_SHARED|SQLITE_SHM_LOCK) && 0==(p->sharedMask & mask)) || (flags==(SQLITE_SHM_EXCLUSIVE|SQLITE_SHM_LOCK)) ){ /* Take the required mutexes. In SETLK_TIMEOUT mode (blocking locks), if ** this is an attempt on an exclusive lock use sqlite3_mutex_try(). If any ** other thread is holding this mutex, then it is either holding or about ** to hold a lock exclusive to the one being requested, and we may ** therefore return SQLITE_BUSY to the caller. ** ** Doing this prevents some deadlock scenarios. For example, thread 1 may ** be a checkpointer blocked waiting on the WRITER lock. And thread 2 ** may be a normal SQL client upgrading to a write transaction. In this ** case thread 2 does a non-blocking request for the WRITER lock. But - ** if it were to use sqlite3_mutex_enter() then it would effectively ** become a (doomed) blocking request, as thread 2 would block until thread ** 1 obtained WRITER and released the mutex. Since thread 2 already holds ** a lock on a read-locking slot at this point, this breaks the ** anti-deadlock rules (see above). */ #ifdef SQLITE_ENABLE_SETLK_TIMEOUT int iMutex; for(iMutex=ofst; iMutex<ofst+n; iMutex++){ if( flags==(SQLITE_SHM_LOCK|SQLITE_SHM_EXCLUSIVE) ){ rc = sqlite3_mutex_try(pShmNode->aMutex[iMutex]); if( rc!=SQLITE_OK ) goto leave_shmnode_mutexes; }else{ sqlite3_mutex_enter(pShmNode->aMutex[iMutex]); } } #else sqlite3_mutex_enter(pShmNode->pShmMutex); #endif if( ALWAYS(rc==SQLITE_OK) ){ if( flags & SQLITE_SHM_UNLOCK ){ /* Case (a) - unlock. */ int bUnlock = 1; assert( (p->exclMask & p->sharedMask)==0 ); assert( !(flags & SQLITE_SHM_EXCLUSIVE) || (p->exclMask & mask)==mask ); assert( !(flags & SQLITE_SHM_SHARED) || (p->sharedMask & mask)==mask ); /* If this is a SHARED lock being unlocked, it is possible that other ** clients within this process are holding the same SHARED lock. In ** this case, set bUnlock to 0 so that the posix lock is not removed ** from the file-descriptor below. */ if( flags & SQLITE_SHM_SHARED ){ assert( n==1 ); assert( aLock[ofst]>=1 ); if( aLock[ofst]>1 ){ bUnlock = 0; aLock[ofst]--; p->sharedMask &= ~mask; } } if( bUnlock ){ rc = unixShmSystemLock(pDbFd, F_UNLCK, ofst+UNIX_SHM_BASE, n); if( rc==SQLITE_OK ){ memset(&aLock[ofst], 0, sizeof(int)*n); p->sharedMask &= ~mask; p->exclMask &= ~mask; } } }else if( flags & SQLITE_SHM_SHARED ){ /* Case (b) - a shared lock. */ if( aLock[ofst]<0 ){ /* An exclusive lock is held by some other connection. BUSY. */ rc = SQLITE_BUSY; }else if( aLock[ofst]==0 ){ rc = unixShmSystemLock(pDbFd, F_RDLCK, ofst+UNIX_SHM_BASE, n); } /* Get the local shared locks */ if( rc==SQLITE_OK ){ p->sharedMask |= mask; aLock[ofst]++; } }else{ /* Case (c) - an exclusive lock. */ int ii; assert( flags==(SQLITE_SHM_LOCK|SQLITE_SHM_EXCLUSIVE) ); assert( (p->sharedMask & mask)==0 ); assert( (p->exclMask & mask)==0 ); /* Make sure no sibling connections hold locks that will block this ** lock. If any do, return SQLITE_BUSY right away. */ for(ii=ofst; ii<ofst+n; ii++){ if( aLock[ii] ){ rc = SQLITE_BUSY; break; } } /* Get the exclusive locks at the system level. Then if successful ** also update the in-memory values. */ if( rc==SQLITE_OK ){ rc = unixShmSystemLock(pDbFd, F_WRLCK, ofst+UNIX_SHM_BASE, n); if( rc==SQLITE_OK ){ p->exclMask |= mask; for(ii=ofst; ii<ofst+n; ii++){ aLock[ii] = -1; } } } } assert( assertLockingArrayOk(pShmNode) ); } /* Drop the mutexes acquired above. */ #ifdef SQLITE_ENABLE_SETLK_TIMEOUT leave_shmnode_mutexes: for(iMutex--; iMutex>=ofst; iMutex--){ sqlite3_mutex_leave(pShmNode->aMutex[iMutex]); } #else sqlite3_mutex_leave(pShmNode->pShmMutex); #endif } OSTRACE(("SHM-LOCK shmid-%d, pid-%d got %03x,%03x\n", p->id, osGetpid(0), p->sharedMask, p->exclMask)); return rc; } /* ** Implement a memory barrier or memory fence on shared memory. ** ** All loads and stores begun before the barrier must complete before ** any load or store begun after the barrier. */ static void unixShmBarrier( sqlite3_file *fd /* Database file holding the shared memory */ ){ UNUSED_PARAMETER(fd); sqlite3MemoryBarrier(); /* compiler-defined memory barrier */ assert( fd->pMethods->xLock==nolockLock || unixFileMutexNotheld((unixFile*)fd) ); unixEnterMutex(); /* Also mutex, for redundancy */ unixLeaveMutex(); } /* ** Close a connection to shared-memory. Delete the underlying ** storage if deleteFlag is true. ** ** If there is no shared memory associated with the connection then this ** routine is a harmless no-op. */ static int unixShmUnmap( sqlite3_file *fd, /* The underlying database file */ int deleteFlag /* Delete shared-memory if true */ ){ unixShm *p; /* The connection to be closed */ unixShmNode *pShmNode; /* The underlying shared-memory file */ unixShm **pp; /* For looping over sibling connections */ unixFile *pDbFd; /* The underlying database file */ pDbFd = (unixFile*)fd; p = pDbFd->pShm; if( p==0 ) return SQLITE_OK; pShmNode = p->pShmNode; assert( pShmNode==pDbFd->pInode->pShmNode ); assert( pShmNode->pInode==pDbFd->pInode ); /* Remove connection p from the set of connections associated ** with pShmNode */ sqlite3_mutex_enter(pShmNode->pShmMutex); for(pp=&pShmNode->pFirst; (*pp)!=p; pp = &(*pp)->pNext){} *pp = p->pNext; /* Free the connection p */ sqlite3_free(p); pDbFd->pShm = 0; sqlite3_mutex_leave(pShmNode->pShmMutex); /* If pShmNode->nRef has reached 0, then close the underlying ** shared-memory file, too */ assert( unixFileMutexNotheld(pDbFd) ); unixEnterMutex(); assert( pShmNode->nRef>0 ); pShmNode->nRef--; if( pShmNode->nRef==0 ){ if( deleteFlag && pShmNode->hShm>=0 ){ osUnlink(pShmNode->zFilename); } unixShmPurge(pDbFd); } unixLeaveMutex(); return SQLITE_OK; } #else # define unixShmMap 0 # define unixShmLock 0 # define unixShmBarrier 0 # define unixShmUnmap 0 #endif /* #ifndef SQLITE_OMIT_WAL */ #if SQLITE_MAX_MMAP_SIZE>0 /* ** If it is currently memory mapped, unmap file pFd. */ static void unixUnmapfile(unixFile *pFd){ assert( pFd->nFetchOut==0 ); if( pFd->pMapRegion ){ osMunmap(pFd->pMapRegion, pFd->mmapSizeActual); pFd->pMapRegion = 0; pFd->mmapSize = 0; pFd->mmapSizeActual = 0; } } /* ** Attempt to set the size of the memory mapping maintained by file ** descriptor pFd to nNew bytes. Any existing mapping is discarded. ** ** If successful, this function sets the following variables: ** ** unixFile.pMapRegion ** unixFile.mmapSize ** unixFile.mmapSizeActual ** ** If unsuccessful, an error message is logged via sqlite3_log() and ** the three variables above are zeroed. In this case SQLite should ** continue accessing the database using the xRead() and xWrite() ** methods. */ static void unixRemapfile( unixFile *pFd, /* File descriptor object */ i64 nNew /* Required mapping size */ ){ const char *zErr = "mmap"; int h = pFd->h; /* File descriptor open on db file */ u8 *pOrig = (u8 *)pFd->pMapRegion; /* Pointer to current file mapping */ u8 *pNew = 0; /* Location of new mapping */ int flags = PROT_READ; /* Flags to pass to mmap() */ assert( pFd->nFetchOut==0 ); assert( nNew>pFd->mmapSize ); assert( nNew<=pFd->mmapSizeMax ); assert( nNew>0 ); assert( pFd->mmapSizeActual>=pFd->mmapSize ); assert( MAP_FAILED!=0 ); #ifdef SQLITE_MMAP_READWRITE if( (pFd->ctrlFlags & UNIXFILE_RDONLY)==0 ) flags |= PROT_WRITE; #endif if( pOrig ){ #if HAVE_MREMAP i64 nReuse = pFd->mmapSize; pNew = osMremap(pOrig, nReuse, nNew, MREMAP_MAYMOVE); zErr = "mremap"; #else const int szSyspage = osGetpagesize(); i64 nReuse = (pFd->mmapSize & ~(szSyspage-1)); u8 *pReq = &pOrig[nReuse]; pNew = osMmap(pReq, nNew-nReuse, flags, MAP_SHARED, h, nReuse); if( pNew!=MAP_FAILED ){ if( pNew!=pReq ){ osMunmap(pNew, nNew - nReuse); pNew = 0; }else{ pNew = pOrig; } } #endif /* The attempt to extend the existing mapping failed. Free it. */ if( pNew==MAP_FAILED || pNew==0 ){ osMunmap(pOrig, nReuse); } } /* If pNew is still NULL, try to create an entirely new mapping. */ if( pNew==0 ){ pNew = osMmap(0, nNew, flags, MAP_SHARED, h, 0); } if( pNew==MAP_FAILED ){ pNew = 0; nNew = 0; unixLogError(SQLITE_OK, zErr, pFd->zPath); /* If the mmap() above failed, assume that all subsequent mmap() calls ** will probably fail too. Fall back to using xRead/xWrite exclusively ** in this case. */ pFd->mmapSizeMax = 0; } pFd->pMapRegion = (void *)pNew; pFd->mmapSize = pFd->mmapSizeActual = nNew; } /* ** Memory map or remap the file opened by file-descriptor pFd (if the file ** is already mapped, the existing mapping is replaced by the new). Or, if ** there already exists a mapping for this file, and there are still ** outstanding xFetch() references to it, this function is a no-op. ** ** If parameter nByte is non-negative, then it is the requested size of ** the mapping to create. Otherwise, if nByte is less than zero, then the ** requested size is the size of the file on disk. The actual size of the ** created mapping is either the requested size or the value configured ** using SQLITE_FCNTL_MMAP_LIMIT, whichever is smaller. ** ** SQLITE_OK is returned if no error occurs (even if the mapping is not ** recreated as a result of outstanding references) or an SQLite error ** code otherwise. */ static int unixMapfile(unixFile *pFd, i64 nMap){ assert( nMap>=0 || pFd->nFetchOut==0 ); assert( nMap>0 || (pFd->mmapSize==0 && pFd->pMapRegion==0) ); if( pFd->nFetchOut>0 ) return SQLITE_OK; if( nMap<0 ){ struct stat statbuf; /* Low-level file information */ if( osFstat(pFd->h, &statbuf) ){ return SQLITE_IOERR_FSTAT; } nMap = statbuf.st_size; } if( nMap>pFd->mmapSizeMax ){ nMap = pFd->mmapSizeMax; } assert( nMap>0 || (pFd->mmapSize==0 && pFd->pMapRegion==0) ); if( nMap!=pFd->mmapSize ){ unixRemapfile(pFd, nMap); } return SQLITE_OK; } #endif /* SQLITE_MAX_MMAP_SIZE>0 */ /* ** If possible, return a pointer to a mapping of file fd starting at offset ** iOff. The mapping must be valid for at least nAmt bytes. ** ** If such a pointer can be obtained, store it in *pp and return SQLITE_OK. ** Or, if one cannot but no error occurs, set *pp to 0 and return SQLITE_OK. ** Finally, if an error does occur, return an SQLite error code. The final ** value of *pp is undefined in this case. ** ** If this function does return a pointer, the caller must eventually ** release the reference by calling unixUnfetch(). */ static int unixFetch(sqlite3_file *fd, i64 iOff, int nAmt, void **pp){ #if SQLITE_MAX_MMAP_SIZE>0 unixFile *pFd = (unixFile *)fd; /* The underlying database file */ #endif *pp = 0; #if SQLITE_MAX_MMAP_SIZE>0 if( pFd->mmapSizeMax>0 ){ /* Ensure that there is always at least a 256 byte buffer of addressable ** memory following the returned page. If the database is corrupt, ** SQLite may overread the page slightly (in practice only a few bytes, ** but 256 is safe, round, number). */ const int nEofBuffer = 256; if( pFd->pMapRegion==0 ){ int rc = unixMapfile(pFd, -1); if( rc!=SQLITE_OK ) return rc; } if( pFd->mmapSize >= (iOff+nAmt+nEofBuffer) ){ *pp = &((u8 *)pFd->pMapRegion)[iOff]; pFd->nFetchOut++; } } #endif return SQLITE_OK; } /* ** If the third argument is non-NULL, then this function releases a ** reference obtained by an earlier call to unixFetch(). The second ** argument passed to this function must be the same as the corresponding ** argument that was passed to the unixFetch() invocation. ** ** Or, if the third argument is NULL, then this function is being called ** to inform the VFS layer that, according to POSIX, any existing mapping ** may now be invalid and should be unmapped. */ static int unixUnfetch(sqlite3_file *fd, i64 iOff, void *p){ #if SQLITE_MAX_MMAP_SIZE>0 unixFile *pFd = (unixFile *)fd; /* The underlying database file */ UNUSED_PARAMETER(iOff); /* If p==0 (unmap the entire file) then there must be no outstanding ** xFetch references. Or, if p!=0 (meaning it is an xFetch reference), ** then there must be at least one outstanding. */ assert( (p==0)==(pFd->nFetchOut==0) ); /* If p!=0, it must match the iOff value. */ assert( p==0 || p==&((u8 *)pFd->pMapRegion)[iOff] ); if( p ){ pFd->nFetchOut--; }else{ unixUnmapfile(pFd); } assert( pFd->nFetchOut>=0 ); #else UNUSED_PARAMETER(fd); UNUSED_PARAMETER(p); UNUSED_PARAMETER(iOff); #endif return SQLITE_OK; } /* ** Here ends the implementation of all sqlite3_file methods. ** ********************** End sqlite3_file Methods ******************************* ******************************************************************************/ /* ** This division contains definitions of sqlite3_io_methods objects that ** implement various file locking strategies. It also contains definitions ** of "finder" functions. A finder-function is used to locate the appropriate ** sqlite3_io_methods object for a particular database file. The pAppData ** field of the sqlite3_vfs VFS objects are initialized to be pointers to ** the correct finder-function for that VFS. ** ** Most finder functions return a pointer to a fixed sqlite3_io_methods ** object. The only interesting finder-function is autolockIoFinder, which ** looks at the filesystem type and tries to guess the best locking ** strategy from that. ** ** For finder-function F, two objects are created: ** ** (1) The real finder-function named "FImpt()". ** ** (2) A constant pointer to this function named just "F". ** ** ** A pointer to the F pointer is used as the pAppData value for VFS ** objects. We have to do this instead of letting pAppData point ** directly at the finder-function since C90 rules prevent a void* ** from be cast into a function pointer. ** ** ** Each instance of this macro generates two objects: ** ** * A constant sqlite3_io_methods object call METHOD that has locking ** methods CLOSE, LOCK, UNLOCK, CKRESLOCK. ** ** * An I/O method finder function called FINDER that returns a pointer ** to the METHOD object in the previous bullet. */ #define IOMETHODS(FINDER,METHOD,VERSION,CLOSE,LOCK,UNLOCK,CKLOCK,SHMMAP) \ static const sqlite3_io_methods METHOD = { \ VERSION, /* iVersion */ \ CLOSE, /* xClose */ \ unixRead, /* xRead */ \ unixWrite, /* xWrite */ \ unixTruncate, /* xTruncate */ \ unixSync, /* xSync */ \ unixFileSize, /* xFileSize */ \ LOCK, /* xLock */ \ UNLOCK, /* xUnlock */ \ CKLOCK, /* xCheckReservedLock */ \ unixFileControl, /* xFileControl */ \ unixSectorSize, /* xSectorSize */ \ unixDeviceCharacteristics, /* xDeviceCapabilities */ \ SHMMAP, /* xShmMap */ \ unixShmLock, /* xShmLock */ \ unixShmBarrier, /* xShmBarrier */ \ unixShmUnmap, /* xShmUnmap */ \ unixFetch, /* xFetch */ \ unixUnfetch, /* xUnfetch */ \ }; \ static const sqlite3_io_methods *FINDER##Impl(const char *z, unixFile *p){ \ UNUSED_PARAMETER(z); UNUSED_PARAMETER(p); \ return &METHOD; \ } \ static const sqlite3_io_methods *(*const FINDER)(const char*,unixFile *p) \ = FINDER##Impl; /* ** Here are all of the sqlite3_io_methods objects for each of the ** locking strategies. Functions that return pointers to these methods ** are also created. */ IOMETHODS( posixIoFinder, /* Finder function name */ posixIoMethods, /* sqlite3_io_methods object name */ 3, /* shared memory and mmap are enabled */ unixClose, /* xClose method */ unixLock, /* xLock method */ unixUnlock, /* xUnlock method */ unixCheckReservedLock, /* xCheckReservedLock method */ unixShmMap /* xShmMap method */ ) IOMETHODS( nolockIoFinder, /* Finder function name */ nolockIoMethods, /* sqlite3_io_methods object name */ 3, /* shared memory and mmap are enabled */ nolockClose, /* xClose method */ nolockLock, /* xLock method */ nolockUnlock, /* xUnlock method */ nolockCheckReservedLock, /* xCheckReservedLock method */ 0 /* xShmMap method */ ) IOMETHODS( dotlockIoFinder, /* Finder function name */ dotlockIoMethods, /* sqlite3_io_methods object name */ 1, /* shared memory is disabled */ dotlockClose, /* xClose method */ dotlockLock, /* xLock method */ dotlockUnlock, /* xUnlock method */ dotlockCheckReservedLock, /* xCheckReservedLock method */ 0 /* xShmMap method */ ) #if SQLITE_ENABLE_LOCKING_STYLE IOMETHODS( flockIoFinder, /* Finder function name */ flockIoMethods, /* sqlite3_io_methods object name */ 1, /* shared memory is disabled */ flockClose, /* xClose method */ flockLock, /* xLock method */ flockUnlock, /* xUnlock method */ flockCheckReservedLock, /* xCheckReservedLock method */ 0 /* xShmMap method */ ) #endif #if OS_VXWORKS IOMETHODS( semIoFinder, /* Finder function name */ semIoMethods, /* sqlite3_io_methods object name */ 1, /* shared memory is disabled */ semXClose, /* xClose method */ semXLock, /* xLock method */ semXUnlock, /* xUnlock method */ semXCheckReservedLock, /* xCheckReservedLock method */ 0 /* xShmMap method */ ) #endif #if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE IOMETHODS( afpIoFinder, /* Finder function name */ afpIoMethods, /* sqlite3_io_methods object name */ 1, /* shared memory is disabled */ afpClose, /* xClose method */ afpLock, /* xLock method */ afpUnlock, /* xUnlock method */ afpCheckReservedLock, /* xCheckReservedLock method */ 0 /* xShmMap method */ ) #endif /* ** The proxy locking method is a "super-method" in the sense that it ** opens secondary file descriptors for the conch and lock files and ** it uses proxy, dot-file, AFP, and flock() locking methods on those ** secondary files. For this reason, the division that implements ** proxy locking is located much further down in the file. But we need ** to go ahead and define the sqlite3_io_methods and finder function ** for proxy locking here. So we forward declare the I/O methods. */ #if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE static int proxyClose(sqlite3_file*); static int proxyLock(sqlite3_file*, int); static int proxyUnlock(sqlite3_file*, int); static int proxyCheckReservedLock(sqlite3_file*, int*); IOMETHODS( proxyIoFinder, /* Finder function name */ proxyIoMethods, /* sqlite3_io_methods object name */ 1, /* shared memory is disabled */ proxyClose, /* xClose method */ proxyLock, /* xLock method */ proxyUnlock, /* xUnlock method */ proxyCheckReservedLock, /* xCheckReservedLock method */ 0 /* xShmMap method */ ) #endif /* nfs lockd on OSX 10.3+ doesn't clear write locks when a read lock is set */ #if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE IOMETHODS( nfsIoFinder, /* Finder function name */ nfsIoMethods, /* sqlite3_io_methods object name */ 1, /* shared memory is disabled */ unixClose, /* xClose method */ unixLock, /* xLock method */ nfsUnlock, /* xUnlock method */ unixCheckReservedLock, /* xCheckReservedLock method */ 0 /* xShmMap method */ ) #endif #if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE /* ** This "finder" function attempts to determine the best locking strategy ** for the database file "filePath". It then returns the sqlite3_io_methods ** object that implements that strategy. ** ** This is for MacOSX only. */ static const sqlite3_io_methods *autolockIoFinderImpl( const char *filePath, /* name of the database file */ unixFile *pNew /* open file object for the database file */ ){ static const struct Mapping { const char *zFilesystem; /* Filesystem type name */ const sqlite3_io_methods *pMethods; /* Appropriate locking method */ } aMap[] = { { "hfs", &posixIoMethods }, { "ufs", &posixIoMethods }, { "afpfs", &afpIoMethods }, { "smbfs", &afpIoMethods }, { "webdav", &nolockIoMethods }, { 0, 0 } }; int i; struct statfs fsInfo; struct flock lockInfo; if( !filePath ){ /* If filePath==NULL that means we are dealing with a transient file ** that does not need to be locked. */ return &nolockIoMethods; } if( statfs(filePath, &fsInfo) != -1 ){ if( fsInfo.f_flags & MNT_RDONLY ){ return &nolockIoMethods; } for(i=0; aMap[i].zFilesystem; i++){ if( strcmp(fsInfo.f_fstypename, aMap[i].zFilesystem)==0 ){ return aMap[i].pMethods; } } } /* Default case. Handles, amongst others, "nfs". ** Test byte-range lock using fcntl(). If the call succeeds, ** assume that the file-system supports POSIX style locks. */ lockInfo.l_len = 1; lockInfo.l_start = 0; lockInfo.l_whence = SEEK_SET; lockInfo.l_type = F_RDLCK; if( osFcntl(pNew->h, F_GETLK, &lockInfo)!=-1 ) { if( strcmp(fsInfo.f_fstypename, "nfs")==0 ){ return &nfsIoMethods; } else { return &posixIoMethods; } }else{ return &dotlockIoMethods; } } static const sqlite3_io_methods *(*const autolockIoFinder)(const char*,unixFile*) = autolockIoFinderImpl; #endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */ #if OS_VXWORKS /* ** This "finder" function for VxWorks checks to see if posix advisory ** locking works. If it does, then that is what is used. If it does not ** work, then fallback to named semaphore locking. */ static const sqlite3_io_methods *vxworksIoFinderImpl( const char *filePath, /* name of the database file */ unixFile *pNew /* the open file object */ ){ struct flock lockInfo; if( !filePath ){ /* If filePath==NULL that means we are dealing with a transient file ** that does not need to be locked. */ return &nolockIoMethods; } /* Test if fcntl() is supported and use POSIX style locks. ** Otherwise fall back to the named semaphore method. */ lockInfo.l_len = 1; lockInfo.l_start = 0; lockInfo.l_whence = SEEK_SET; lockInfo.l_type = F_RDLCK; if( osFcntl(pNew->h, F_GETLK, &lockInfo)!=-1 ) { return &posixIoMethods; }else{ return &semIoMethods; } } static const sqlite3_io_methods *(*const vxworksIoFinder)(const char*,unixFile*) = vxworksIoFinderImpl; #endif /* OS_VXWORKS */ /* ** An abstract type for a pointer to an IO method finder function: */ typedef const sqlite3_io_methods *(*finder_type)(const char*,unixFile*); /**************************************************************************** **************************** sqlite3_vfs methods **************************** ** ** This division contains the implementation of methods on the ** sqlite3_vfs object. */ /* ** Initialize the contents of the unixFile structure pointed to by pId. */ static int fillInUnixFile( sqlite3_vfs *pVfs, /* Pointer to vfs object */ int h, /* Open file descriptor of file being opened */ sqlite3_file *pId, /* Write to the unixFile structure here */ const char *zFilename, /* Name of the file being opened */ int ctrlFlags /* Zero or more UNIXFILE_* values */ ){ const sqlite3_io_methods *pLockingStyle; unixFile *pNew = (unixFile *)pId; int rc = SQLITE_OK; assert( pNew->pInode==NULL ); /* No locking occurs in temporary files */ assert( zFilename!=0 || (ctrlFlags & UNIXFILE_NOLOCK)!=0 ); OSTRACE(("OPEN %-3d %s\n", h, zFilename)); pNew->h = h; pNew->pVfs = pVfs; pNew->zPath = zFilename; pNew->ctrlFlags = (u8)ctrlFlags; #if SQLITE_MAX_MMAP_SIZE>0 pNew->mmapSizeMax = sqlite3GlobalConfig.szMmap; #endif if( sqlite3_uri_boolean(((ctrlFlags & UNIXFILE_URI) ? zFilename : 0), "psow", SQLITE_POWERSAFE_OVERWRITE) ){ pNew->ctrlFlags |= UNIXFILE_PSOW; } if( strcmp(pVfs->zName,"unix-excl")==0 ){ pNew->ctrlFlags |= UNIXFILE_EXCL; } #if OS_VXWORKS pNew->pId = vxworksFindFileId(zFilename); if( pNew->pId==0 ){ ctrlFlags |= UNIXFILE_NOLOCK; rc = SQLITE_NOMEM_BKPT; } #endif if( ctrlFlags & UNIXFILE_NOLOCK ){ pLockingStyle = &nolockIoMethods; }else{ pLockingStyle = (**(finder_type*)pVfs->pAppData)(zFilename, pNew); #if SQLITE_ENABLE_LOCKING_STYLE /* Cache zFilename in the locking context (AFP and dotlock override) for ** proxyLock activation is possible (remote proxy is based on db name) ** zFilename remains valid until file is closed, to support */ pNew->lockingContext = (void*)zFilename; #endif } if( pLockingStyle == &posixIoMethods #if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE || pLockingStyle == &nfsIoMethods #endif ){ unixEnterMutex(); rc = findInodeInfo(pNew, &pNew->pInode); if( rc!=SQLITE_OK ){ /* If an error occurred in findInodeInfo(), close the file descriptor ** immediately, before releasing the mutex. findInodeInfo() may fail ** in two scenarios: ** ** (a) A call to fstat() failed. ** (b) A malloc failed. ** ** Scenario (b) may only occur if the process is holding no other ** file descriptors open on the same file. If there were other file ** descriptors on this file, then no malloc would be required by ** findInodeInfo(). If this is the case, it is quite safe to close ** handle h - as it is guaranteed that no posix locks will be released ** by doing so. ** ** If scenario (a) caused the error then things are not so safe. The ** implicit assumption here is that if fstat() fails, things are in ** such bad shape that dropping a lock or two doesn't matter much. */ robust_close(pNew, h, __LINE__); h = -1; } unixLeaveMutex(); } #if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__) else if( pLockingStyle == &afpIoMethods ){ /* AFP locking uses the file path so it needs to be included in ** the afpLockingContext. */ afpLockingContext *pCtx; pNew->lockingContext = pCtx = sqlite3_malloc64( sizeof(*pCtx) ); if( pCtx==0 ){ rc = SQLITE_NOMEM_BKPT; }else{ /* NB: zFilename exists and remains valid until the file is closed ** according to requirement F11141. So we do not need to make a ** copy of the filename. */ pCtx->dbPath = zFilename; pCtx->reserved = 0; srandomdev(); unixEnterMutex(); rc = findInodeInfo(pNew, &pNew->pInode); if( rc!=SQLITE_OK ){ sqlite3_free(pNew->lockingContext); robust_close(pNew, h, __LINE__); h = -1; } unixLeaveMutex(); } } #endif else if( pLockingStyle == &dotlockIoMethods ){ /* Dotfile locking uses the file path so it needs to be included in ** the dotlockLockingContext */ char *zLockFile; int nFilename; assert( zFilename!=0 ); nFilename = (int)strlen(zFilename) + 6; zLockFile = (char *)sqlite3_malloc64(nFilename); if( zLockFile==0 ){ rc = SQLITE_NOMEM_BKPT; }else{ sqlite3_snprintf(nFilename, zLockFile, "%s" DOTLOCK_SUFFIX, zFilename); } pNew->lockingContext = zLockFile; } #if OS_VXWORKS else if( pLockingStyle == &semIoMethods ){ /* Named semaphore locking uses the file path so it needs to be ** included in the semLockingContext */ unixEnterMutex(); rc = findInodeInfo(pNew, &pNew->pInode); if( (rc==SQLITE_OK) && (pNew->pInode->pSem==NULL) ){ char *zSemName = pNew->pInode->aSemName; int n; sqlite3_snprintf(MAX_PATHNAME, zSemName, "/%s.sem", pNew->pId->zCanonicalName); for( n=1; zSemName[n]; n++ ) if( zSemName[n]=='/' ) zSemName[n] = '_'; pNew->pInode->pSem = sem_open(zSemName, O_CREAT, 0666, 1); if( pNew->pInode->pSem == SEM_FAILED ){ rc = SQLITE_NOMEM_BKPT; pNew->pInode->aSemName[0] = '\0'; } } unixLeaveMutex(); } #endif storeLastErrno(pNew, 0); #if OS_VXWORKS if( rc!=SQLITE_OK ){ if( h>=0 ){ robust_close(pNew, h, __LINE__); h = -1; } if( pNew->ctrlFlags & UNIXFILE_DELETE ){ osUnlink(zFilename); } if( pNew->pId ){ vxworksReleaseFileId(pNew->pId); pNew->pId = 0; } } #endif if( rc!=SQLITE_OK ){ if( h>=0 ) robust_close(pNew, h, __LINE__); }else{ pId->pMethods = pLockingStyle; OpenCounter(+1); verifyDbFile(pNew); } return rc; } /* ** Return the name of a directory in which to put temporary files. ** If no suitable temporary file directory can be found, return NULL. ** ** The return value might be a string obtained from getenv() and so ** the return value should not be used after any call to setenv() or ** putenv() as that value might have been freed. */ static const char *unixTempFileDir(void){ unsigned int i; struct stat buf; const char *zDir; for(i=0; i<7; i++){ switch( i ){ case 0: zDir = sqlite3_temp_directory; break; case 1: zDir = getenv("SQLITE_TMPDIR"); break; case 2: zDir = getenv("TMPDIR"); break; case 3: zDir = "/var/tmp"; break; case 4: zDir = "/usr/tmp"; break; case 5: zDir = "/tmp"; break; default: zDir = "."; break; } if( zDir!=0 #if OS_VXWORKS && zDir[0]=='/' #endif && osStat(zDir, &buf)==0 && S_ISDIR(buf.st_mode) && osAccess(zDir, 03)==0 ){ return zDir; } } return 0; } /* ** Create a temporary file name in zBuf. zBuf must be allocated ** by the calling process and must be big enough to hold at least ** pVfs->mxPathname bytes. */ static int unixGetTempname(int nBuf, char *zBuf){ const char *zDir; int iLimit = 0; int rc = SQLITE_OK; /* It's odd to simulate an io-error here, but really this is just ** using the io-error infrastructure to test that SQLite handles this ** function failing. */ zBuf[0] = 0; SimulateIOError( return SQLITE_IOERR ); sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_TEMPDIR)); zDir = unixTempFileDir(); if( zDir==0 ){ rc = SQLITE_IOERR_GETTEMPPATH; }else{ do{ u64 r; sqlite3_randomness(sizeof(r), &r); assert( nBuf>2 ); zBuf[nBuf-2] = 0; sqlite3_snprintf(nBuf, zBuf, "%s/"SQLITE_TEMP_FILE_PREFIX"%llx%c", zDir, r, 0); if( zBuf[nBuf-2]!=0 || (iLimit++)>10 ){ rc = SQLITE_ERROR; break; } }while( osAccess(zBuf,0)==0 ); } sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_TEMPDIR)); return rc; } #if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__) /* ** Routine to transform a unixFile into a proxy-locking unixFile. ** Implementation in the proxy-lock division, but used by unixOpen() ** if SQLITE_PREFER_PROXY_LOCKING is defined. */ static int proxyTransformUnixFile(unixFile*, const char*); #endif /* ** Search for an unused file descriptor that was opened on the database ** file (not a journal or super-journal file) identified by pathname ** zPath with SQLITE_OPEN_XXX flags matching those passed as the second ** argument to this function. ** ** Such a file descriptor may exist if a database connection was closed ** but the associated file descriptor could not be closed because some ** other file descriptor open on the same file is holding a file-lock. ** Refer to comments in the unixClose() function and the lengthy comment ** describing "Posix Advisory Locking" at the start of this file for ** further details. Also, ticket #4018. ** ** If a suitable file descriptor is found, then it is returned. If no ** such file descriptor is located, -1 is returned. */ static UnixUnusedFd *findReusableFd(const char *zPath, int flags){ UnixUnusedFd *pUnused = 0; /* Do not search for an unused file descriptor on vxworks. Not because ** vxworks would not benefit from the change (it might, we're not sure), ** but because no way to test it is currently available. It is better ** not to risk breaking vxworks support for the sake of such an obscure ** feature. */ #if !OS_VXWORKS struct stat sStat; /* Results of stat() call */ unixEnterMutex(); /* A stat() call may fail for various reasons. If this happens, it is ** almost certain that an open() call on the same path will also fail. ** For this reason, if an error occurs in the stat() call here, it is ** ignored and -1 is returned. The caller will try to open a new file ** descriptor on the same path, fail, and return an error to SQLite. ** ** Even if a subsequent open() call does succeed, the consequences of ** not searching for a reusable file descriptor are not dire. */ if( inodeList!=0 && 0==osStat(zPath, &sStat) ){ unixInodeInfo *pInode; pInode = inodeList; while( pInode && (pInode->fileId.dev!=sStat.st_dev || pInode->fileId.ino!=(u64)sStat.st_ino) ){ pInode = pInode->pNext; } if( pInode ){ UnixUnusedFd **pp; assert( sqlite3_mutex_notheld(pInode->pLockMutex) ); sqlite3_mutex_enter(pInode->pLockMutex); flags &= (SQLITE_OPEN_READONLY|SQLITE_OPEN_READWRITE); for(pp=&pInode->pUnused; *pp && (*pp)->flags!=flags; pp=&((*pp)->pNext)); pUnused = *pp; if( pUnused ){ *pp = pUnused->pNext; } sqlite3_mutex_leave(pInode->pLockMutex); } } unixLeaveMutex(); #endif /* if !OS_VXWORKS */ return pUnused; } /* ** Find the mode, uid and gid of file zFile. */ static int getFileMode( const char *zFile, /* File name */ mode_t *pMode, /* OUT: Permissions of zFile */ uid_t *pUid, /* OUT: uid of zFile. */ gid_t *pGid /* OUT: gid of zFile. */ ){ struct stat sStat; /* Output of stat() on database file */ int rc = SQLITE_OK; if( 0==osStat(zFile, &sStat) ){ *pMode = sStat.st_mode & 0777; *pUid = sStat.st_uid; *pGid = sStat.st_gid; }else{ rc = SQLITE_IOERR_FSTAT; } return rc; } /* ** This function is called by unixOpen() to determine the unix permissions ** to create new files with. If no error occurs, then SQLITE_OK is returned ** and a value suitable for passing as the third argument to open(2) is ** written to *pMode. If an IO error occurs, an SQLite error code is ** returned and the value of *pMode is not modified. ** ** In most cases, this routine sets *pMode to 0, which will become ** an indication to robust_open() to create the file using ** SQLITE_DEFAULT_FILE_PERMISSIONS adjusted by the umask. ** But if the file being opened is a WAL or regular journal file, then ** this function queries the file-system for the permissions on the ** corresponding database file and sets *pMode to this value. Whenever ** possible, WAL and journal files are created using the same permissions ** as the associated database file. ** ** If the SQLITE_ENABLE_8_3_NAMES option is enabled, then the ** original filename is unavailable. But 8_3_NAMES is only used for ** FAT filesystems and permissions do not matter there, so just use ** the default permissions. In 8_3_NAMES mode, leave *pMode set to zero. */ static int findCreateFileMode( const char *zPath, /* Path of file (possibly) being created */ int flags, /* Flags passed as 4th argument to xOpen() */ mode_t *pMode, /* OUT: Permissions to open file with */ uid_t *pUid, /* OUT: uid to set on the file */ gid_t *pGid /* OUT: gid to set on the file */ ){ int rc = SQLITE_OK; /* Return Code */ *pMode = 0; *pUid = 0; *pGid = 0; if( flags & (SQLITE_OPEN_WAL|SQLITE_OPEN_MAIN_JOURNAL) ){ char zDb[MAX_PATHNAME+1]; /* Database file path */ int nDb; /* Number of valid bytes in zDb */ /* zPath is a path to a WAL or journal file. The following block derives ** the path to the associated database file from zPath. This block handles ** the following naming conventions: ** ** "<path to db>-journal" ** "<path to db>-wal" ** "<path to db>-journalNN" ** "<path to db>-walNN" ** ** where NN is a decimal number. The NN naming schemes are ** used by the test_multiplex.c module. ** ** In normal operation, the journal file name will always contain ** a '-' character. However in 8+3 filename mode, or if a corrupt ** rollback journal specifies a super-journal with a goofy name, then ** the '-' might be missing or the '-' might be the first character in ** the filename. In that case, just return SQLITE_OK with *pMode==0. */ nDb = sqlite3Strlen30(zPath) - 1; while( nDb>0 && zPath[nDb]!='.' ){ if( zPath[nDb]=='-' ){ memcpy(zDb, zPath, nDb); zDb[nDb] = '\0'; rc = getFileMode(zDb, pMode, pUid, pGid); break; } nDb--; } }else if( flags & SQLITE_OPEN_DELETEONCLOSE ){ *pMode = 0600; }else if( flags & SQLITE_OPEN_URI ){ /* If this is a main database file and the file was opened using a URI ** filename, check for the "modeof" parameter. If present, interpret ** its value as a filename and try to copy the mode, uid and gid from ** that file. */ const char *z = sqlite3_uri_parameter(zPath, "modeof"); if( z ){ rc = getFileMode(z, pMode, pUid, pGid); } } return rc; } /* ** Open the file zPath. ** ** Previously, the SQLite OS layer used three functions in place of this ** one: ** ** sqlite3OsOpenReadWrite(); ** sqlite3OsOpenReadOnly(); ** sqlite3OsOpenExclusive(); ** ** These calls correspond to the following combinations of flags: ** ** ReadWrite() -> (READWRITE | CREATE) ** ReadOnly() -> (READONLY) ** OpenExclusive() -> (READWRITE | CREATE | EXCLUSIVE) ** ** The old OpenExclusive() accepted a boolean argument - "delFlag". If ** true, the file was configured to be automatically deleted when the ** file handle closed. To achieve the same effect using this new ** interface, add the DELETEONCLOSE flag to those specified above for ** OpenExclusive(). */ static int unixOpen( sqlite3_vfs *pVfs, /* The VFS for which this is the xOpen method */ const char *zPath, /* Pathname of file to be opened */ sqlite3_file *pFile, /* The file descriptor to be filled in */ int flags, /* Input flags to control the opening */ int *pOutFlags /* Output flags returned to SQLite core */ ){ unixFile *p = (unixFile *)pFile; int fd = -1; /* File descriptor returned by open() */ int openFlags = 0; /* Flags to pass to open() */ int eType = flags&0x0FFF00; /* Type of file to open */ int noLock; /* True to omit locking primitives */ int rc = SQLITE_OK; /* Function Return Code */ int ctrlFlags = 0; /* UNIXFILE_* flags */ int isExclusive = (flags & SQLITE_OPEN_EXCLUSIVE); int isDelete = (flags & SQLITE_OPEN_DELETEONCLOSE); int isCreate = (flags & SQLITE_OPEN_CREATE); int isReadonly = (flags & SQLITE_OPEN_READONLY); int isReadWrite = (flags & SQLITE_OPEN_READWRITE); #if SQLITE_ENABLE_LOCKING_STYLE int isAutoProxy = (flags & SQLITE_OPEN_AUTOPROXY); #endif #if defined(__APPLE__) || SQLITE_ENABLE_LOCKING_STYLE struct statfs fsInfo; #endif /* If creating a super- or main-file journal, this function will open ** a file-descriptor on the directory too. The first time unixSync() ** is called the directory file descriptor will be fsync()ed and close()d. */ int isNewJrnl = (isCreate && ( eType==SQLITE_OPEN_SUPER_JOURNAL || eType==SQLITE_OPEN_MAIN_JOURNAL || eType==SQLITE_OPEN_WAL )); /* If argument zPath is a NULL pointer, this function is required to open ** a temporary file. Use this buffer to store the file name in. */ char zTmpname[MAX_PATHNAME+2]; const char *zName = zPath; /* Check the following statements are true: ** ** (a) Exactly one of the READWRITE and READONLY flags must be set, and ** (b) if CREATE is set, then READWRITE must also be set, and ** (c) if EXCLUSIVE is set, then CREATE must also be set. ** (d) if DELETEONCLOSE is set, then CREATE must also be set. */ assert((isReadonly==0 || isReadWrite==0) && (isReadWrite || isReadonly)); assert(isCreate==0 || isReadWrite); assert(isExclusive==0 || isCreate); assert(isDelete==0 || isCreate); /* The main DB, main journal, WAL file and super-journal are never ** automatically deleted. Nor are they ever temporary files. */ assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_DB ); assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_JOURNAL ); assert( (!isDelete && zName) || eType!=SQLITE_OPEN_SUPER_JOURNAL ); assert( (!isDelete && zName) || eType!=SQLITE_OPEN_WAL ); /* Assert that the upper layer has set one of the "file-type" flags. */ assert( eType==SQLITE_OPEN_MAIN_DB || eType==SQLITE_OPEN_TEMP_DB || eType==SQLITE_OPEN_MAIN_JOURNAL || eType==SQLITE_OPEN_TEMP_JOURNAL || eType==SQLITE_OPEN_SUBJOURNAL || eType==SQLITE_OPEN_SUPER_JOURNAL || eType==SQLITE_OPEN_TRANSIENT_DB || eType==SQLITE_OPEN_WAL ); #if OS_VXWORKS /* The file-ID mechanism used in Vxworks requires that all pathnames ** provided to unixOpen must be absolute pathnames. */ if( zPath!=0 && zPath[0]!='/' ){ return SQLITE_CANTOPEN; } #endif /* Detect a pid change and reset the PRNG. There is a race condition ** here such that two or more threads all trying to open databases at ** the same instant might all reset the PRNG. But multiple resets ** are harmless. */ if( randomnessPid!=osGetpid(0) ){ randomnessPid = osGetpid(0); sqlite3_randomness(0,0); } memset(p, 0, sizeof(unixFile)); #ifdef SQLITE_ASSERT_NO_FILES /* Applications that never read or write a persistent disk files */ assert( zName==0 ); #endif if( eType==SQLITE_OPEN_MAIN_DB ){ UnixUnusedFd *pUnused; pUnused = findReusableFd(zName, flags); if( pUnused ){ fd = pUnused->fd; }else{ pUnused = sqlite3_malloc64(sizeof(*pUnused)); if( !pUnused ){ return SQLITE_NOMEM_BKPT; } } p->pPreallocatedUnused = pUnused; /* Database filenames are double-zero terminated if they are not ** URIs with parameters. Hence, they can always be passed into ** sqlite3_uri_parameter(). */ assert( (flags & SQLITE_OPEN_URI) || zName[strlen(zName)+1]==0 ); }else if( !zName ){ /* If zName is NULL, the upper layer is requesting a temp file. */ assert( isDelete ); assert( !isNewJrnl ); assert( isExclusive ); assert( isReadWrite ); #if defined(__linux__) && defined(O_TMPFILE) /* On systems that support O_TMPFILE, use that flag to create a more ** secure temporary file that cannot be accessed by other processes */ zName = unixTempFileDir(); if( zName && (fd = robust_open(zName, O_RDWR|O_CREAT|O_EXCL|O_TMPFILE, 0600))>=0 ){ rc = fillInUnixFile(pVfs, fd, pFile, zPath, ctrlFlags); goto open_finished; } #endif rc = unixGetTempname(pVfs->mxPathname, zTmpname); if( rc!=SQLITE_OK ){ return rc; } zName = zTmpname; /* Generated temporary filenames are always double-zero terminated ** for use by sqlite3_uri_parameter(). */ assert( zName[strlen(zName)+1]==0 ); } /* Determine the value of the flags parameter passed to POSIX function ** open(). These must be calculated even if open() is not called, as ** they may be stored as part of the file handle and used by the ** 'conch file' locking functions later on. */ if( isReadonly ) openFlags |= O_RDONLY; if( isReadWrite ) openFlags |= O_RDWR; if( isCreate ) openFlags |= O_CREAT; if( isExclusive ) openFlags |= (O_EXCL|O_NOFOLLOW); openFlags |= (O_LARGEFILE|O_BINARY|O_NOFOLLOW); if( fd<0 ){ mode_t openMode; /* Permissions to create file with */ uid_t uid; /* Userid for the file */ gid_t gid; /* Groupid for the file */ rc = findCreateFileMode(zName, flags, &openMode, &uid, &gid); if( rc!=SQLITE_OK ){ assert( !p->pPreallocatedUnused ); assert( eType==SQLITE_OPEN_WAL || eType==SQLITE_OPEN_MAIN_JOURNAL ); return rc; } fd = robust_open(zName, openFlags, openMode); OSTRACE(("OPENX %-3d %s 0%o\n", fd, zName, openFlags)); assert( !isExclusive || (openFlags & O_CREAT)!=0 ); if( fd<0 ){ if( isNewJrnl && errno==EACCES && osAccess(zName, F_OK) ){ /* If unable to create a journal because the directory is not ** writable, change the error code to indicate that. */ rc = SQLITE_READONLY_DIRECTORY; }else if( errno!=EISDIR && isReadWrite ){ /* Failed to open the file for read/write access. Try read-only. */ UnixUnusedFd *pReadonly = 0; flags &= ~(SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE); openFlags &= ~(O_RDWR|O_CREAT); flags |= SQLITE_OPEN_READONLY; openFlags |= O_RDONLY; isReadonly = 1; pReadonly = findReusableFd(zName, flags); if( pReadonly ){ fd = pReadonly->fd; sqlite3_free(pReadonly); }else{ fd = robust_open(zName, openFlags, openMode); } } } if( fd<0 ){ int rc2 = unixLogError(SQLITE_CANTOPEN_BKPT, "open", zName); if( rc==SQLITE_OK ) rc = rc2; goto open_finished; } /* The owner of the rollback journal or WAL file should always be the ** same as the owner of the database file. Try to ensure that this is ** the case. The chown() system call will be a no-op if the current ** process lacks root privileges, be we should at least try. Without ** this step, if a root process opens a database file, it can leave ** behinds a journal/WAL that is owned by root and hence make the ** database inaccessible to unprivileged processes. ** ** If openMode==0, then that means uid and gid are not set correctly ** (probably because SQLite is configured to use 8+3 filename mode) and ** in that case we do not want to attempt the chown(). */ if( openMode && (flags & (SQLITE_OPEN_WAL|SQLITE_OPEN_MAIN_JOURNAL))!=0 ){ robustFchown(fd, uid, gid); } } assert( fd>=0 ); if( pOutFlags ){ *pOutFlags = flags; } if( p->pPreallocatedUnused ){ p->pPreallocatedUnused->fd = fd; p->pPreallocatedUnused->flags = flags & (SQLITE_OPEN_READONLY|SQLITE_OPEN_READWRITE); } if( isDelete ){ #if OS_VXWORKS zPath = zName; #elif defined(SQLITE_UNLINK_AFTER_CLOSE) zPath = sqlite3_mprintf("%s", zName); if( zPath==0 ){ robust_close(p, fd, __LINE__); return SQLITE_NOMEM_BKPT; } #else osUnlink(zName); #endif } #if SQLITE_ENABLE_LOCKING_STYLE else{ p->openFlags = openFlags; } #endif #if defined(__APPLE__) || SQLITE_ENABLE_LOCKING_STYLE if( fstatfs(fd, &fsInfo) == -1 ){ storeLastErrno(p, errno); robust_close(p, fd, __LINE__); return SQLITE_IOERR_ACCESS; } if (0 == strncmp("msdos", fsInfo.f_fstypename, 5)) { ((unixFile*)pFile)->fsFlags |= SQLITE_FSFLAGS_IS_MSDOS; } if (0 == strncmp("exfat", fsInfo.f_fstypename, 5)) { ((unixFile*)pFile)->fsFlags |= SQLITE_FSFLAGS_IS_MSDOS; } #endif /* Set up appropriate ctrlFlags */ if( isDelete ) ctrlFlags |= UNIXFILE_DELETE; if( isReadonly ) ctrlFlags |= UNIXFILE_RDONLY; noLock = eType!=SQLITE_OPEN_MAIN_DB; if( noLock ) ctrlFlags |= UNIXFILE_NOLOCK; if( isNewJrnl ) ctrlFlags |= UNIXFILE_DIRSYNC; if( flags & SQLITE_OPEN_URI ) ctrlFlags |= UNIXFILE_URI; #if SQLITE_ENABLE_LOCKING_STYLE #if SQLITE_PREFER_PROXY_LOCKING isAutoProxy = 1; #endif if( isAutoProxy && (zPath!=NULL) && (!noLock) && pVfs->xOpen ){ char *envforce = getenv("SQLITE_FORCE_PROXY_LOCKING"); int useProxy = 0; /* SQLITE_FORCE_PROXY_LOCKING==1 means force always use proxy, 0 means ** never use proxy, NULL means use proxy for non-local files only. */ if( envforce!=NULL ){ useProxy = atoi(envforce)>0; }else{ useProxy = !(fsInfo.f_flags&MNT_LOCAL); } if( useProxy ){ rc = fillInUnixFile(pVfs, fd, pFile, zPath, ctrlFlags); if( rc==SQLITE_OK ){ rc = proxyTransformUnixFile((unixFile*)pFile, ":auto:"); if( rc!=SQLITE_OK ){ /* Use unixClose to clean up the resources added in fillInUnixFile ** and clear all the structure's references. Specifically, ** pFile->pMethods will be NULL so sqlite3OsClose will be a no-op */ unixClose(pFile); return rc; } } goto open_finished; } } #endif assert( zPath==0 || zPath[0]=='/' || eType==SQLITE_OPEN_SUPER_JOURNAL || eType==SQLITE_OPEN_MAIN_JOURNAL || eType==SQLITE_OPEN_TEMP_JOURNAL ); rc = fillInUnixFile(pVfs, fd, pFile, zPath, ctrlFlags); open_finished: if( rc!=SQLITE_OK ){ sqlite3_free(p->pPreallocatedUnused); } return rc; } /* ** Delete the file at zPath. If the dirSync argument is true, fsync() ** the directory after deleting the file. */ static int unixDelete( sqlite3_vfs *NotUsed, /* VFS containing this as the xDelete method */ const char *zPath, /* Name of file to be deleted */ int dirSync /* If true, fsync() directory after deleting file */ ){ int rc = SQLITE_OK; UNUSED_PARAMETER(NotUsed); SimulateIOError(return SQLITE_IOERR_DELETE); if( osUnlink(zPath)==(-1) ){ if( errno==ENOENT #if OS_VXWORKS || osAccess(zPath,0)!=0 #endif ){ rc = SQLITE_IOERR_DELETE_NOENT; }else{ rc = unixLogError(SQLITE_IOERR_DELETE, "unlink", zPath); } return rc; } #ifndef SQLITE_DISABLE_DIRSYNC if( (dirSync & 1)!=0 ){ int fd; rc = osOpenDirectory(zPath, &fd); if( rc==SQLITE_OK ){ if( full_fsync(fd,0,0) ){ rc = unixLogError(SQLITE_IOERR_DIR_FSYNC, "fsync", zPath); } robust_close(0, fd, __LINE__); }else{ assert( rc==SQLITE_CANTOPEN ); rc = SQLITE_OK; } } #endif return rc; } /* ** Test the existence of or access permissions of file zPath. The ** test performed depends on the value of flags: ** ** SQLITE_ACCESS_EXISTS: Return 1 if the file exists ** SQLITE_ACCESS_READWRITE: Return 1 if the file is read and writable. ** SQLITE_ACCESS_READONLY: Return 1 if the file is readable. ** ** Otherwise return 0. */ static int unixAccess( sqlite3_vfs *NotUsed, /* The VFS containing this xAccess method */ const char *zPath, /* Path of the file to examine */ int flags, /* What do we want to learn about the zPath file? */ int *pResOut /* Write result boolean here */ ){ UNUSED_PARAMETER(NotUsed); SimulateIOError( return SQLITE_IOERR_ACCESS; ); assert( pResOut!=0 ); /* The spec says there are three possible values for flags. But only ** two of them are actually used */ assert( flags==SQLITE_ACCESS_EXISTS || flags==SQLITE_ACCESS_READWRITE ); if( flags==SQLITE_ACCESS_EXISTS ){ struct stat buf; *pResOut = 0==osStat(zPath, &buf) && (!S_ISREG(buf.st_mode) || buf.st_size>0); }else{ *pResOut = osAccess(zPath, W_OK|R_OK)==0; } return SQLITE_OK; } /* ** A pathname under construction */ typedef struct DbPath DbPath; struct DbPath { int rc; /* Non-zero following any error */ int nSymlink; /* Number of symlinks resolved */ char *zOut; /* Write the pathname here */ int nOut; /* Bytes of space available to zOut[] */ int nUsed; /* Bytes of zOut[] currently being used */ }; /* Forward reference */ static void appendAllPathElements(DbPath*,const char*); /* ** Append a single path element to the DbPath under construction */ static void appendOnePathElement( DbPath *pPath, /* Path under construction, to which to append zName */ const char *zName, /* Name to append to pPath. Not zero-terminated */ int nName /* Number of significant bytes in zName */ ){ assert( nName>0 ); assert( zName!=0 ); if( zName[0]=='.' ){ if( nName==1 ) return; if( zName[1]=='.' && nName==2 ){ if( pPath->nUsed>1 ){ assert( pPath->zOut[0]=='/' ); while( pPath->zOut[--pPath->nUsed]!='/' ){} } return; } } if( pPath->nUsed + nName + 2 >= pPath->nOut ){ pPath->rc = SQLITE_ERROR; return; } pPath->zOut[pPath->nUsed++] = '/'; memcpy(&pPath->zOut[pPath->nUsed], zName, nName); pPath->nUsed += nName; #if defined(HAVE_READLINK) && defined(HAVE_LSTAT) if( pPath->rc==SQLITE_OK ){ const char *zIn; struct stat buf; pPath->zOut[pPath->nUsed] = 0; zIn = pPath->zOut; if( osLstat(zIn, &buf)!=0 ){ if( errno!=ENOENT ){ pPath->rc = unixLogError(SQLITE_CANTOPEN_BKPT, "lstat", zIn); } }else if( S_ISLNK(buf.st_mode) ){ ssize_t got; char zLnk[SQLITE_MAX_PATHLEN+2]; if( pPath->nSymlink++ > SQLITE_MAX_SYMLINK ){ pPath->rc = SQLITE_CANTOPEN_BKPT; return; } got = osReadlink(zIn, zLnk, sizeof(zLnk)-2); if( got<=0 || got>=(ssize_t)sizeof(zLnk)-2 ){ pPath->rc = unixLogError(SQLITE_CANTOPEN_BKPT, "readlink", zIn); return; } zLnk[got] = 0; if( zLnk[0]=='/' ){ pPath->nUsed = 0; }else{ pPath->nUsed -= nName + 1; } appendAllPathElements(pPath, zLnk); } } #endif } /* ** Append all path elements in zPath to the DbPath under construction. */ static void appendAllPathElements( DbPath *pPath, /* Path under construction, to which to append zName */ const char *zPath /* Path to append to pPath. Is zero-terminated */ ){ int i = 0; int j = 0; do{ while( zPath[i] && zPath[i]!='/' ){ i++; } if( i>j ){ appendOnePathElement(pPath, &zPath[j], i-j); } j = i+1; }while( zPath[i++] ); } /* ** Turn a relative pathname into a full pathname. The relative path ** is stored as a nul-terminated string in the buffer pointed to by ** zPath. ** ** zOut points to a buffer of at least sqlite3_vfs.mxPathname bytes ** (in this case, MAX_PATHNAME bytes). The full-path is written to ** this buffer before returning. */ static int unixFullPathname( sqlite3_vfs *pVfs, /* Pointer to vfs object */ const char *zPath, /* Possibly relative input path */ int nOut, /* Size of output buffer in bytes */ char *zOut /* Output buffer */ ){ DbPath path; UNUSED_PARAMETER(pVfs); path.rc = 0; path.nUsed = 0; path.nSymlink = 0; path.nOut = nOut; path.zOut = zOut; if( zPath[0]!='/' ){ char zPwd[SQLITE_MAX_PATHLEN+2]; if( osGetcwd(zPwd, sizeof(zPwd)-2)==0 ){ return unixLogError(SQLITE_CANTOPEN_BKPT, "getcwd", zPath); } appendAllPathElements(&path, zPwd); } appendAllPathElements(&path, zPath); zOut[path.nUsed] = 0; if( path.rc || path.nUsed<2 ) return SQLITE_CANTOPEN_BKPT; if( path.nSymlink ) return SQLITE_OK_SYMLINK; return SQLITE_OK; } #ifndef SQLITE_OMIT_LOAD_EXTENSION /* ** Interfaces for opening a shared library, finding entry points ** within the shared library, and closing the shared library. */ #include <dlfcn.h> static void *unixDlOpen(sqlite3_vfs *NotUsed, const char *zFilename){ UNUSED_PARAMETER(NotUsed); return dlopen(zFilename, RTLD_NOW | RTLD_GLOBAL); } /* ** SQLite calls this function immediately after a call to unixDlSym() or ** unixDlOpen() fails (returns a null pointer). If a more detailed error ** message is available, it is written to zBufOut. If no error message ** is available, zBufOut is left unmodified and SQLite uses a default ** error message. */ static void unixDlError(sqlite3_vfs *NotUsed, int nBuf, char *zBufOut){ const char *zErr; UNUSED_PARAMETER(NotUsed); unixEnterMutex(); zErr = dlerror(); if( zErr ){ sqlite3_snprintf(nBuf, zBufOut, "%s", zErr); } unixLeaveMutex(); } static void (*unixDlSym(sqlite3_vfs *NotUsed, void *p, const char*zSym))(void){ /* ** GCC with -pedantic-errors says that C90 does not allow a void* to be ** cast into a pointer to a function. And yet the library dlsym() routine ** returns a void* which is really a pointer to a function. So how do we ** use dlsym() with -pedantic-errors? ** ** Variable x below is defined to be a pointer to a function taking ** parameters void* and const char* and returning a pointer to a function. ** We initialize x by assigning it a pointer to the dlsym() function. ** (That assignment requires a cast.) Then we call the function that ** x points to. ** ** This work-around is unlikely to work correctly on any system where ** you really cannot cast a function pointer into void*. But then, on the ** other hand, dlsym() will not work on such a system either, so we have ** not really lost anything. */ void (*(*x)(void*,const char*))(void); UNUSED_PARAMETER(NotUsed); x = (void(*(*)(void*,const char*))(void))dlsym; return (*x)(p, zSym); } static void unixDlClose(sqlite3_vfs *NotUsed, void *pHandle){ UNUSED_PARAMETER(NotUsed); dlclose(pHandle); } #else /* if SQLITE_OMIT_LOAD_EXTENSION is defined: */ #define unixDlOpen 0 #define unixDlError 0 #define unixDlSym 0 #define unixDlClose 0 #endif /* ** Write nBuf bytes of random data to the supplied buffer zBuf. */ static int unixRandomness(sqlite3_vfs *NotUsed, int nBuf, char *zBuf){ UNUSED_PARAMETER(NotUsed); assert((size_t)nBuf>=(sizeof(time_t)+sizeof(int))); /* We have to initialize zBuf to prevent valgrind from reporting ** errors. The reports issued by valgrind are incorrect - we would ** prefer that the randomness be increased by making use of the ** uninitialized space in zBuf - but valgrind errors tend to worry ** some users. Rather than argue, it seems easier just to initialize ** the whole array and silence valgrind, even if that means less randomness ** in the random seed. ** ** When testing, initializing zBuf[] to zero is all we do. That means ** that we always use the same random number sequence. This makes the ** tests repeatable. */ memset(zBuf, 0, nBuf); randomnessPid = osGetpid(0); #if !defined(SQLITE_TEST) && !defined(SQLITE_OMIT_RANDOMNESS) { int fd, got; fd = robust_open("/dev/urandom", O_RDONLY, 0); if( fd<0 ){ time_t t; time(&t); memcpy(zBuf, &t, sizeof(t)); memcpy(&zBuf[sizeof(t)], &randomnessPid, sizeof(randomnessPid)); assert( sizeof(t)+sizeof(randomnessPid)<=(size_t)nBuf ); nBuf = sizeof(t) + sizeof(randomnessPid); }else{ do{ got = osRead(fd, zBuf, nBuf); }while( got<0 && errno==EINTR ); robust_close(0, fd, __LINE__); } } #endif return nBuf; } /* ** Sleep for a little while. Return the amount of time slept. ** The argument is the number of microseconds we want to sleep. ** The return value is the number of microseconds of sleep actually ** requested from the underlying operating system, a number which ** might be greater than or equal to the argument, but not less ** than the argument. */ static int unixSleep(sqlite3_vfs *NotUsed, int microseconds){ #if !defined(HAVE_NANOSLEEP) || HAVE_NANOSLEEP+0 struct timespec sp; sp.tv_sec = microseconds / 1000000; sp.tv_nsec = (microseconds % 1000000) * 1000; /* Almost all modern unix systems support nanosleep(). But if you are ** compiling for one of the rare exceptions, you can use ** -DHAVE_NANOSLEEP=0 (perhaps in conjunction with -DHAVE_USLEEP if ** usleep() is available) in order to bypass the use of nanosleep() */ nanosleep(&sp, NULL); UNUSED_PARAMETER(NotUsed); return microseconds; #elif defined(HAVE_USLEEP) && HAVE_USLEEP if( microseconds>=1000000 ) sleep(microseconds/1000000); if( microseconds%1000000 ) usleep(microseconds%1000000); UNUSED_PARAMETER(NotUsed); return microseconds; #else int seconds = (microseconds+999999)/1000000; sleep(seconds); UNUSED_PARAMETER(NotUsed); return seconds*1000000; #endif } /* ** The following variable, if set to a non-zero value, is interpreted as ** the number of seconds since 1970 and is used to set the result of ** sqlite3OsCurrentTime() during testing. */ #ifdef SQLITE_TEST int sqlite3_current_time = 0; /* Fake system time in seconds since 1970. */ #endif /* ** Find the current time (in Universal Coordinated Time). Write into *piNow ** the current time and date as a Julian Day number times 86_400_000. In ** other words, write into *piNow the number of milliseconds since the Julian ** epoch of noon in Greenwich on November 24, 4714 B.C according to the ** proleptic Gregorian calendar. ** ** On success, return SQLITE_OK. Return SQLITE_ERROR if the time and date ** cannot be found. */ static int unixCurrentTimeInt64(sqlite3_vfs *NotUsed, sqlite3_int64 *piNow){ static const sqlite3_int64 unixEpoch = 24405875*(sqlite3_int64)8640000; int rc = SQLITE_OK; #if defined(NO_GETTOD) time_t t; time(&t); *piNow = ((sqlite3_int64)t)*1000 + unixEpoch; #elif OS_VXWORKS struct timespec sNow; clock_gettime(CLOCK_REALTIME, &sNow); *piNow = unixEpoch + 1000*(sqlite3_int64)sNow.tv_sec + sNow.tv_nsec/1000000; #else struct timeval sNow; (void)gettimeofday(&sNow, 0); /* Cannot fail given valid arguments */ *piNow = unixEpoch + 1000*(sqlite3_int64)sNow.tv_sec + sNow.tv_usec/1000; #endif #ifdef SQLITE_TEST if( sqlite3_current_time ){ *piNow = 1000*(sqlite3_int64)sqlite3_current_time + unixEpoch; } #endif UNUSED_PARAMETER(NotUsed); return rc; } #ifndef SQLITE_OMIT_DEPRECATED /* ** Find the current time (in Universal Coordinated Time). Write the ** current time and date as a Julian Day number into *prNow and ** return 0. Return 1 if the time and date cannot be found. */ static int unixCurrentTime(sqlite3_vfs *NotUsed, double *prNow){ sqlite3_int64 i = 0; int rc; UNUSED_PARAMETER(NotUsed); rc = unixCurrentTimeInt64(0, &i); *prNow = i/86400000.0; return rc; } #else # define unixCurrentTime 0 #endif /* ** The xGetLastError() method is designed to return a better ** low-level error message when operating-system problems come up ** during SQLite operation. Only the integer return code is currently ** used. */ static int unixGetLastError(sqlite3_vfs *NotUsed, int NotUsed2, char *NotUsed3){ UNUSED_PARAMETER(NotUsed); UNUSED_PARAMETER(NotUsed2); UNUSED_PARAMETER(NotUsed3); return errno; } /* ************************ End of sqlite3_vfs methods *************************** ******************************************************************************/ /****************************************************************************** ************************** Begin Proxy Locking ******************************** ** ** Proxy locking is a "uber-locking-method" in this sense: It uses the ** other locking methods on secondary lock files. Proxy locking is a ** meta-layer over top of the primitive locking implemented above. For ** this reason, the division that implements of proxy locking is deferred ** until late in the file (here) after all of the other I/O methods have ** been defined - so that the primitive locking methods are available ** as services to help with the implementation of proxy locking. ** **** ** ** The default locking schemes in SQLite use byte-range locks on the ** database file to coordinate safe, concurrent access by multiple readers ** and writers [http://sqlite.org/lockingv3.html]. The five file locking ** states (UNLOCKED, PENDING, SHARED, RESERVED, EXCLUSIVE) are implemented ** as POSIX read & write locks over fixed set of locations (via fsctl), ** on AFP and SMB only exclusive byte-range locks are available via fsctl ** with _IOWR('z', 23, struct ByteRangeLockPB2) to track the same 5 states. ** To simulate a F_RDLCK on the shared range, on AFP a randomly selected ** address in the shared range is taken for a SHARED lock, the entire ** shared range is taken for an EXCLUSIVE lock): ** ** PENDING_BYTE 0x40000000 ** RESERVED_BYTE 0x40000001 ** SHARED_RANGE 0x40000002 -> 0x40000200 ** ** This works well on the local file system, but shows a nearly 100x ** slowdown in read performance on AFP because the AFP client disables ** the read cache when byte-range locks are present. Enabling the read ** cache exposes a cache coherency problem that is present on all OS X ** supported network file systems. NFS and AFP both observe the ** close-to-open semantics for ensuring cache coherency ** [http://nfs.sourceforge.net/#faq_a8], which does not effectively ** address the requirements for concurrent database access by multiple ** readers and writers ** [http://www.nabble.com/SQLite-on-NFS-cache-coherency-td15655701.html]. ** ** To address the performance and cache coherency issues, proxy file locking ** changes the way database access is controlled by limiting access to a ** single host at a time and moving file locks off of the database file ** and onto a proxy file on the local file system. ** ** ** Using proxy locks ** ----------------- ** ** C APIs ** ** sqlite3_file_control(db, dbname, SQLITE_FCNTL_SET_LOCKPROXYFILE, ** <proxy_path> | ":auto:"); ** sqlite3_file_control(db, dbname, SQLITE_FCNTL_GET_LOCKPROXYFILE, ** &<proxy_path>); ** ** ** SQL pragmas ** ** PRAGMA [database.]lock_proxy_file=<proxy_path> | :auto: ** PRAGMA [database.]lock_proxy_file ** ** Specifying ":auto:" means that if there is a conch file with a matching ** host ID in it, the proxy path in the conch file will be used, otherwise ** a proxy path based on the user's temp dir ** (via confstr(_CS_DARWIN_USER_TEMP_DIR,...)) will be used and the ** actual proxy file name is generated from the name and path of the ** database file. For example: ** ** For database path "/Users/me/foo.db" ** The lock path will be "<tmpdir>/sqliteplocks/_Users_me_foo.db:auto:") ** ** Once a lock proxy is configured for a database connection, it can not ** be removed, however it may be switched to a different proxy path via ** the above APIs (assuming the conch file is not being held by another ** connection or process). ** ** ** How proxy locking works ** ----------------------- ** ** Proxy file locking relies primarily on two new supporting files: ** ** * conch file to limit access to the database file to a single host ** at a time ** ** * proxy file to act as a proxy for the advisory locks normally ** taken on the database ** ** The conch file - to use a proxy file, sqlite must first "hold the conch" ** by taking an sqlite-style shared lock on the conch file, reading the ** contents and comparing the host's unique host ID (see below) and lock ** proxy path against the values stored in the conch. The conch file is ** stored in the same directory as the database file and the file name ** is patterned after the database file name as ".<databasename>-conch". ** If the conch file does not exist, or its contents do not match the ** host ID and/or proxy path, then the lock is escalated to an exclusive ** lock and the conch file contents is updated with the host ID and proxy ** path and the lock is downgraded to a shared lock again. If the conch ** is held by another process (with a shared lock), the exclusive lock ** will fail and SQLITE_BUSY is returned. ** ** The proxy file - a single-byte file used for all advisory file locks ** normally taken on the database file. This allows for safe sharing ** of the database file for multiple readers and writers on the same ** host (the conch ensures that they all use the same local lock file). ** ** Requesting the lock proxy does not immediately take the conch, it is ** only taken when the first request to lock database file is made. ** This matches the semantics of the traditional locking behavior, where ** opening a connection to a database file does not take a lock on it. ** The shared lock and an open file descriptor are maintained until ** the connection to the database is closed. ** ** The proxy file and the lock file are never deleted so they only need ** to be created the first time they are used. ** ** Configuration options ** --------------------- ** ** SQLITE_PREFER_PROXY_LOCKING ** ** Database files accessed on non-local file systems are ** automatically configured for proxy locking, lock files are ** named automatically using the same logic as ** PRAGMA lock_proxy_file=":auto:" ** ** SQLITE_PROXY_DEBUG ** ** Enables the logging of error messages during host id file ** retrieval and creation ** ** LOCKPROXYDIR ** ** Overrides the default directory used for lock proxy files that ** are named automatically via the ":auto:" setting ** ** SQLITE_DEFAULT_PROXYDIR_PERMISSIONS ** ** Permissions to use when creating a directory for storing the ** lock proxy files, only used when LOCKPROXYDIR is not set. ** ** ** As mentioned above, when compiled with SQLITE_PREFER_PROXY_LOCKING, ** setting the environment variable SQLITE_FORCE_PROXY_LOCKING to 1 will ** force proxy locking to be used for every database file opened, and 0 ** will force automatic proxy locking to be disabled for all database ** files (explicitly calling the SQLITE_FCNTL_SET_LOCKPROXYFILE pragma or ** sqlite_file_control API is not affected by SQLITE_FORCE_PROXY_LOCKING). */ /* ** Proxy locking is only available on MacOSX */ #if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE /* ** The proxyLockingContext has the path and file structures for the remote ** and local proxy files in it */ typedef struct proxyLockingContext proxyLockingContext; struct proxyLockingContext { unixFile *conchFile; /* Open conch file */ char *conchFilePath; /* Name of the conch file */ unixFile *lockProxy; /* Open proxy lock file */ char *lockProxyPath; /* Name of the proxy lock file */ char *dbPath; /* Name of the open file */ int conchHeld; /* 1 if the conch is held, -1 if lockless */ int nFails; /* Number of conch taking failures */ void *oldLockingContext; /* Original lockingcontext to restore on close */ sqlite3_io_methods const *pOldMethod; /* Original I/O methods for close */ }; /* ** The proxy lock file path for the database at dbPath is written into lPath, ** which must point to valid, writable memory large enough for a maxLen length ** file path. */ static int proxyGetLockPath(const char *dbPath, char *lPath, size_t maxLen){ int len; int dbLen; int i; #ifdef LOCKPROXYDIR len = strlcpy(lPath, LOCKPROXYDIR, maxLen); #else # ifdef _CS_DARWIN_USER_TEMP_DIR { if( !confstr(_CS_DARWIN_USER_TEMP_DIR, lPath, maxLen) ){ OSTRACE(("GETLOCKPATH failed %s errno=%d pid=%d\n", lPath, errno, osGetpid(0))); return SQLITE_IOERR_LOCK; } len = strlcat(lPath, "sqliteplocks", maxLen); } # else len = strlcpy(lPath, "/tmp/", maxLen); # endif #endif if( lPath[len-1]!='/' ){ len = strlcat(lPath, "/", maxLen); } /* transform the db path to a unique cache name */ dbLen = (int)strlen(dbPath); for( i=0; i<dbLen && (i+len+7)<(int)maxLen; i++){ char c = dbPath[i]; lPath[i+len] = (c=='/')?'_':c; } lPath[i+len]='\0'; strlcat(lPath, ":auto:", maxLen); OSTRACE(("GETLOCKPATH proxy lock path=%s pid=%d\n", lPath, osGetpid(0))); return SQLITE_OK; } /* ** Creates the lock file and any missing directories in lockPath */ static int proxyCreateLockPath(const char *lockPath){ int i, len; char buf[MAXPATHLEN]; int start = 0; assert(lockPath!=NULL); /* try to create all the intermediate directories */ len = (int)strlen(lockPath); buf[0] = lockPath[0]; for( i=1; i<len; i++ ){ if( lockPath[i] == '/' && (i - start > 0) ){ /* only mkdir if leaf dir != "." or "/" or ".." */ if( i-start>2 || (i-start==1 && buf[start] != '.' && buf[start] != '/') || (i-start==2 && buf[start] != '.' && buf[start+1] != '.') ){ buf[i]='\0'; if( osMkdir(buf, SQLITE_DEFAULT_PROXYDIR_PERMISSIONS) ){ int err=errno; if( err!=EEXIST ) { OSTRACE(("CREATELOCKPATH FAILED creating %s, " "'%s' proxy lock path=%s pid=%d\n", buf, strerror(err), lockPath, osGetpid(0))); return err; } } } start=i+1; } buf[i] = lockPath[i]; } OSTRACE(("CREATELOCKPATH proxy lock path=%s pid=%d\n",lockPath,osGetpid(0))); return 0; } /* ** Create a new VFS file descriptor (stored in memory obtained from ** sqlite3_malloc) and open the file named "path" in the file descriptor. ** ** The caller is responsible not only for closing the file descriptor ** but also for freeing the memory associated with the file descriptor. */ static int proxyCreateUnixFile( const char *path, /* path for the new unixFile */ unixFile **ppFile, /* unixFile created and returned by ref */ int islockfile /* if non zero missing dirs will be created */ ) { int fd = -1; unixFile *pNew; int rc = SQLITE_OK; int openFlags = O_RDWR | O_CREAT | O_NOFOLLOW; sqlite3_vfs dummyVfs; int terrno = 0; UnixUnusedFd *pUnused = NULL; /* 1. first try to open/create the file ** 2. if that fails, and this is a lock file (not-conch), try creating ** the parent directories and then try again. ** 3. if that fails, try to open the file read-only ** otherwise return BUSY (if lock file) or CANTOPEN for the conch file */ pUnused = findReusableFd(path, openFlags); if( pUnused ){ fd = pUnused->fd; }else{ pUnused = sqlite3_malloc64(sizeof(*pUnused)); if( !pUnused ){ return SQLITE_NOMEM_BKPT; } } if( fd<0 ){ fd = robust_open(path, openFlags, 0); terrno = errno; if( fd<0 && errno==ENOENT && islockfile ){ if( proxyCreateLockPath(path) == SQLITE_OK ){ fd = robust_open(path, openFlags, 0); } } } if( fd<0 ){ openFlags = O_RDONLY | O_NOFOLLOW; fd = robust_open(path, openFlags, 0); terrno = errno; } if( fd<0 ){ if( islockfile ){ return SQLITE_BUSY; } switch (terrno) { case EACCES: return SQLITE_PERM; case EIO: return SQLITE_IOERR_LOCK; /* even though it is the conch */ default: return SQLITE_CANTOPEN_BKPT; } } pNew = (unixFile *)sqlite3_malloc64(sizeof(*pNew)); if( pNew==NULL ){ rc = SQLITE_NOMEM_BKPT; goto end_create_proxy; } memset(pNew, 0, sizeof(unixFile)); pNew->openFlags = openFlags; memset(&dummyVfs, 0, sizeof(dummyVfs)); dummyVfs.pAppData = (void*)&autolockIoFinder; dummyVfs.zName = "dummy"; pUnused->fd = fd; pUnused->flags = openFlags; pNew->pPreallocatedUnused = pUnused; rc = fillInUnixFile(&dummyVfs, fd, (sqlite3_file*)pNew, path, 0); if( rc==SQLITE_OK ){ *ppFile = pNew; return SQLITE_OK; } end_create_proxy: robust_close(pNew, fd, __LINE__); sqlite3_free(pNew); sqlite3_free(pUnused); return rc; } #ifdef SQLITE_TEST /* simulate multiple hosts by creating unique hostid file paths */ int sqlite3_hostid_num = 0; #endif #define PROXY_HOSTIDLEN 16 /* conch file host id length */ #if HAVE_GETHOSTUUID /* Not always defined in the headers as it ought to be */ extern int gethostuuid(uuid_t id, const struct timespec *wait); #endif /* get the host ID via gethostuuid(), pHostID must point to PROXY_HOSTIDLEN ** bytes of writable memory. */ static int proxyGetHostID(unsigned char *pHostID, int *pError){ assert(PROXY_HOSTIDLEN == sizeof(uuid_t)); memset(pHostID, 0, PROXY_HOSTIDLEN); #if HAVE_GETHOSTUUID { struct timespec timeout = {1, 0}; /* 1 sec timeout */ if( gethostuuid(pHostID, &timeout) ){ int err = errno; if( pError ){ *pError = err; } return SQLITE_IOERR; } } #else UNUSED_PARAMETER(pError); #endif #ifdef SQLITE_TEST /* simulate multiple hosts by creating unique hostid file paths */ if( sqlite3_hostid_num != 0){ pHostID[0] = (char)(pHostID[0] + (char)(sqlite3_hostid_num & 0xFF)); } #endif return SQLITE_OK; } /* The conch file contains the header, host id and lock file path */ #define PROXY_CONCHVERSION 2 /* 1-byte header, 16-byte host id, path */ #define PROXY_HEADERLEN 1 /* conch file header length */ #define PROXY_PATHINDEX (PROXY_HEADERLEN+PROXY_HOSTIDLEN) #define PROXY_MAXCONCHLEN (PROXY_HEADERLEN+PROXY_HOSTIDLEN+MAXPATHLEN) /* ** Takes an open conch file, copies the contents to a new path and then moves ** it back. The newly created file's file descriptor is assigned to the ** conch file structure and finally the original conch file descriptor is ** closed. Returns zero if successful. */ static int proxyBreakConchLock(unixFile *pFile, uuid_t myHostID){ proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; unixFile *conchFile = pCtx->conchFile; char tPath[MAXPATHLEN]; char buf[PROXY_MAXCONCHLEN]; char *cPath = pCtx->conchFilePath; size_t readLen = 0; size_t pathLen = 0; char errmsg[64] = ""; int fd = -1; int rc = -1; UNUSED_PARAMETER(myHostID); /* create a new path by replace the trailing '-conch' with '-break' */ pathLen = strlcpy(tPath, cPath, MAXPATHLEN); if( pathLen>MAXPATHLEN || pathLen<6 || (strlcpy(&tPath[pathLen-5], "break", 6) != 5) ){ sqlite3_snprintf(sizeof(errmsg),errmsg,"path error (len %d)",(int)pathLen); goto end_breaklock; } /* read the conch content */ readLen = osPread(conchFile->h, buf, PROXY_MAXCONCHLEN, 0); if( readLen<PROXY_PATHINDEX ){ sqlite3_snprintf(sizeof(errmsg),errmsg,"read error (len %d)",(int)readLen); goto end_breaklock; } /* write it out to the temporary break file */ fd = robust_open(tPath, (O_RDWR|O_CREAT|O_EXCL|O_NOFOLLOW), 0); if( fd<0 ){ sqlite3_snprintf(sizeof(errmsg), errmsg, "create failed (%d)", errno); goto end_breaklock; } if( osPwrite(fd, buf, readLen, 0) != (ssize_t)readLen ){ sqlite3_snprintf(sizeof(errmsg), errmsg, "write failed (%d)", errno); goto end_breaklock; } if( rename(tPath, cPath) ){ sqlite3_snprintf(sizeof(errmsg), errmsg, "rename failed (%d)", errno); goto end_breaklock; } rc = 0; fprintf(stderr, "broke stale lock on %s\n", cPath); robust_close(pFile, conchFile->h, __LINE__); conchFile->h = fd; conchFile->openFlags = O_RDWR | O_CREAT; end_breaklock: if( rc ){ if( fd>=0 ){ osUnlink(tPath); robust_close(pFile, fd, __LINE__); } fprintf(stderr, "failed to break stale lock on %s, %s\n", cPath, errmsg); } return rc; } /* Take the requested lock on the conch file and break a stale lock if the ** host id matches. */ static int proxyConchLock(unixFile *pFile, uuid_t myHostID, int lockType){ proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; unixFile *conchFile = pCtx->conchFile; int rc = SQLITE_OK; int nTries = 0; struct timespec conchModTime; memset(&conchModTime, 0, sizeof(conchModTime)); do { rc = conchFile->pMethod->xLock((sqlite3_file*)conchFile, lockType); nTries ++; if( rc==SQLITE_BUSY ){ /* If the lock failed (busy): * 1st try: get the mod time of the conch, wait 0.5s and try again. * 2nd try: fail if the mod time changed or host id is different, wait * 10 sec and try again * 3rd try: break the lock unless the mod time has changed. */ struct stat buf; if( osFstat(conchFile->h, &buf) ){ storeLastErrno(pFile, errno); return SQLITE_IOERR_LOCK; } if( nTries==1 ){ conchModTime = buf.st_mtimespec; unixSleep(0,500000); /* wait 0.5 sec and try the lock again*/ continue; } assert( nTries>1 ); if( conchModTime.tv_sec != buf.st_mtimespec.tv_sec || conchModTime.tv_nsec != buf.st_mtimespec.tv_nsec ){ return SQLITE_BUSY; } if( nTries==2 ){ char tBuf[PROXY_MAXCONCHLEN]; int len = osPread(conchFile->h, tBuf, PROXY_MAXCONCHLEN, 0); if( len<0 ){ storeLastErrno(pFile, errno); return SQLITE_IOERR_LOCK; } if( len>PROXY_PATHINDEX && tBuf[0]==(char)PROXY_CONCHVERSION){ /* don't break the lock if the host id doesn't match */ if( 0!=memcmp(&tBuf[PROXY_HEADERLEN], myHostID, PROXY_HOSTIDLEN) ){ return SQLITE_BUSY; } }else{ /* don't break the lock on short read or a version mismatch */ return SQLITE_BUSY; } unixSleep(0,10000000); /* wait 10 sec and try the lock again */ continue; } assert( nTries==3 ); if( 0==proxyBreakConchLock(pFile, myHostID) ){ rc = SQLITE_OK; if( lockType==EXCLUSIVE_LOCK ){ rc = conchFile->pMethod->xLock((sqlite3_file*)conchFile, SHARED_LOCK); } if( !rc ){ rc = conchFile->pMethod->xLock((sqlite3_file*)conchFile, lockType); } } } } while( rc==SQLITE_BUSY && nTries<3 ); return rc; } /* Takes the conch by taking a shared lock and read the contents conch, if ** lockPath is non-NULL, the host ID and lock file path must match. A NULL ** lockPath means that the lockPath in the conch file will be used if the ** host IDs match, or a new lock path will be generated automatically ** and written to the conch file. */ static int proxyTakeConch(unixFile *pFile){ proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; if( pCtx->conchHeld!=0 ){ return SQLITE_OK; }else{ unixFile *conchFile = pCtx->conchFile; uuid_t myHostID; int pError = 0; char readBuf[PROXY_MAXCONCHLEN]; char lockPath[MAXPATHLEN]; char *tempLockPath = NULL; int rc = SQLITE_OK; int createConch = 0; int hostIdMatch = 0; int readLen = 0; int tryOldLockPath = 0; int forceNewLockPath = 0; OSTRACE(("TAKECONCH %d for %s pid=%d\n", conchFile->h, (pCtx->lockProxyPath ? pCtx->lockProxyPath : ":auto:"), osGetpid(0))); rc = proxyGetHostID(myHostID, &pError); if( (rc&0xff)==SQLITE_IOERR ){ storeLastErrno(pFile, pError); goto end_takeconch; } rc = proxyConchLock(pFile, myHostID, SHARED_LOCK); if( rc!=SQLITE_OK ){ goto end_takeconch; } /* read the existing conch file */ readLen = seekAndRead((unixFile*)conchFile, 0, readBuf, PROXY_MAXCONCHLEN); if( readLen<0 ){ /* I/O error: lastErrno set by seekAndRead */ storeLastErrno(pFile, conchFile->lastErrno); rc = SQLITE_IOERR_READ; goto end_takeconch; }else if( readLen<=(PROXY_HEADERLEN+PROXY_HOSTIDLEN) || readBuf[0]!=(char)PROXY_CONCHVERSION ){ /* a short read or version format mismatch means we need to create a new ** conch file. */ createConch = 1; } /* if the host id matches and the lock path already exists in the conch ** we'll try to use the path there, if we can't open that path, we'll ** retry with a new auto-generated path */ do { /* in case we need to try again for an :auto: named lock file */ if( !createConch && !forceNewLockPath ){ hostIdMatch = !memcmp(&readBuf[PROXY_HEADERLEN], myHostID, PROXY_HOSTIDLEN); /* if the conch has data compare the contents */ if( !pCtx->lockProxyPath ){ /* for auto-named local lock file, just check the host ID and we'll ** use the local lock file path that's already in there */ if( hostIdMatch ){ size_t pathLen = (readLen - PROXY_PATHINDEX); if( pathLen>=MAXPATHLEN ){ pathLen=MAXPATHLEN-1; } memcpy(lockPath, &readBuf[PROXY_PATHINDEX], pathLen); lockPath[pathLen] = 0; tempLockPath = lockPath; tryOldLockPath = 1; /* create a copy of the lock path if the conch is taken */ goto end_takeconch; } }else if( hostIdMatch && !strncmp(pCtx->lockProxyPath, &readBuf[PROXY_PATHINDEX], readLen-PROXY_PATHINDEX) ){ /* conch host and lock path match */ goto end_takeconch; } } /* if the conch isn't writable and doesn't match, we can't take it */ if( (conchFile->openFlags&O_RDWR) == 0 ){ rc = SQLITE_BUSY; goto end_takeconch; } /* either the conch didn't match or we need to create a new one */ if( !pCtx->lockProxyPath ){ proxyGetLockPath(pCtx->dbPath, lockPath, MAXPATHLEN); tempLockPath = lockPath; /* create a copy of the lock path _only_ if the conch is taken */ } /* update conch with host and path (this will fail if other process ** has a shared lock already), if the host id matches, use the big ** stick. */ futimes(conchFile->h, NULL); if( hostIdMatch && !createConch ){ if( conchFile->pInode && conchFile->pInode->nShared>1 ){ /* We are trying for an exclusive lock but another thread in this ** same process is still holding a shared lock. */ rc = SQLITE_BUSY; } else { rc = proxyConchLock(pFile, myHostID, EXCLUSIVE_LOCK); } }else{ rc = proxyConchLock(pFile, myHostID, EXCLUSIVE_LOCK); } if( rc==SQLITE_OK ){ char writeBuffer[PROXY_MAXCONCHLEN]; int writeSize = 0; writeBuffer[0] = (char)PROXY_CONCHVERSION; memcpy(&writeBuffer[PROXY_HEADERLEN], myHostID, PROXY_HOSTIDLEN); if( pCtx->lockProxyPath!=NULL ){ strlcpy(&writeBuffer[PROXY_PATHINDEX], pCtx->lockProxyPath, MAXPATHLEN); }else{ strlcpy(&writeBuffer[PROXY_PATHINDEX], tempLockPath, MAXPATHLEN); } writeSize = PROXY_PATHINDEX + strlen(&writeBuffer[PROXY_PATHINDEX]); robust_ftruncate(conchFile->h, writeSize); rc = unixWrite((sqlite3_file *)conchFile, writeBuffer, writeSize, 0); full_fsync(conchFile->h,0,0); /* If we created a new conch file (not just updated the contents of a ** valid conch file), try to match the permissions of the database */ if( rc==SQLITE_OK && createConch ){ struct stat buf; int err = osFstat(pFile->h, &buf); if( err==0 ){ mode_t cmode = buf.st_mode&(S_IRUSR|S_IWUSR | S_IRGRP|S_IWGRP | S_IROTH|S_IWOTH); /* try to match the database file R/W permissions, ignore failure */ #ifndef SQLITE_PROXY_DEBUG osFchmod(conchFile->h, cmode); #else do{ rc = osFchmod(conchFile->h, cmode); }while( rc==(-1) && errno==EINTR ); if( rc!=0 ){ int code = errno; fprintf(stderr, "fchmod %o FAILED with %d %s\n", cmode, code, strerror(code)); } else { fprintf(stderr, "fchmod %o SUCCEDED\n",cmode); } }else{ int code = errno; fprintf(stderr, "STAT FAILED[%d] with %d %s\n", err, code, strerror(code)); #endif } } } conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, SHARED_LOCK); end_takeconch: OSTRACE(("TRANSPROXY: CLOSE %d\n", pFile->h)); if( rc==SQLITE_OK && pFile->openFlags ){ int fd; if( pFile->h>=0 ){ robust_close(pFile, pFile->h, __LINE__); } pFile->h = -1; fd = robust_open(pCtx->dbPath, pFile->openFlags, 0); OSTRACE(("TRANSPROXY: OPEN %d\n", fd)); if( fd>=0 ){ pFile->h = fd; }else{ rc=SQLITE_CANTOPEN_BKPT; /* SQLITE_BUSY? proxyTakeConch called during locking */ } } if( rc==SQLITE_OK && !pCtx->lockProxy ){ char *path = tempLockPath ? tempLockPath : pCtx->lockProxyPath; rc = proxyCreateUnixFile(path, &pCtx->lockProxy, 1); if( rc!=SQLITE_OK && rc!=SQLITE_NOMEM && tryOldLockPath ){ /* we couldn't create the proxy lock file with the old lock file path ** so try again via auto-naming */ forceNewLockPath = 1; tryOldLockPath = 0; continue; /* go back to the do {} while start point, try again */ } } if( rc==SQLITE_OK ){ /* Need to make a copy of path if we extracted the value ** from the conch file or the path was allocated on the stack */ if( tempLockPath ){ pCtx->lockProxyPath = sqlite3DbStrDup(0, tempLockPath); if( !pCtx->lockProxyPath ){ rc = SQLITE_NOMEM_BKPT; } } } if( rc==SQLITE_OK ){ pCtx->conchHeld = 1; if( pCtx->lockProxy->pMethod == &afpIoMethods ){ afpLockingContext *afpCtx; afpCtx = (afpLockingContext *)pCtx->lockProxy->lockingContext; afpCtx->dbPath = pCtx->lockProxyPath; } } else { conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, NO_LOCK); } OSTRACE(("TAKECONCH %d %s\n", conchFile->h, rc==SQLITE_OK?"ok":"failed")); return rc; } while (1); /* in case we need to retry the :auto: lock file - ** we should never get here except via the 'continue' call. */ } } /* ** If pFile holds a lock on a conch file, then release that lock. */ static int proxyReleaseConch(unixFile *pFile){ int rc = SQLITE_OK; /* Subroutine return code */ proxyLockingContext *pCtx; /* The locking context for the proxy lock */ unixFile *conchFile; /* Name of the conch file */ pCtx = (proxyLockingContext *)pFile->lockingContext; conchFile = pCtx->conchFile; OSTRACE(("RELEASECONCH %d for %s pid=%d\n", conchFile->h, (pCtx->lockProxyPath ? pCtx->lockProxyPath : ":auto:"), osGetpid(0))); if( pCtx->conchHeld>0 ){ rc = conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, NO_LOCK); } pCtx->conchHeld = 0; OSTRACE(("RELEASECONCH %d %s\n", conchFile->h, (rc==SQLITE_OK ? "ok" : "failed"))); return rc; } /* ** Given the name of a database file, compute the name of its conch file. ** Store the conch filename in memory obtained from sqlite3_malloc64(). ** Make *pConchPath point to the new name. Return SQLITE_OK on success ** or SQLITE_NOMEM if unable to obtain memory. ** ** The caller is responsible for ensuring that the allocated memory ** space is eventually freed. ** ** *pConchPath is set to NULL if a memory allocation error occurs. */ static int proxyCreateConchPathname(char *dbPath, char **pConchPath){ int i; /* Loop counter */ int len = (int)strlen(dbPath); /* Length of database filename - dbPath */ char *conchPath; /* buffer in which to construct conch name */ /* Allocate space for the conch filename and initialize the name to ** the name of the original database file. */ *pConchPath = conchPath = (char *)sqlite3_malloc64(len + 8); if( conchPath==0 ){ return SQLITE_NOMEM_BKPT; } memcpy(conchPath, dbPath, len+1); /* now insert a "." before the last / character */ for( i=(len-1); i>=0; i-- ){ if( conchPath[i]=='/' ){ i++; break; } } conchPath[i]='.'; while ( i<len ){ conchPath[i+1]=dbPath[i]; i++; } /* append the "-conch" suffix to the file */ memcpy(&conchPath[i+1], "-conch", 7); assert( (int)strlen(conchPath) == len+7 ); return SQLITE_OK; } /* Takes a fully configured proxy locking-style unix file and switches ** the local lock file path */ static int switchLockProxyPath(unixFile *pFile, const char *path) { proxyLockingContext *pCtx = (proxyLockingContext*)pFile->lockingContext; char *oldPath = pCtx->lockProxyPath; int rc = SQLITE_OK; if( pFile->eFileLock!=NO_LOCK ){ return SQLITE_BUSY; } /* nothing to do if the path is NULL, :auto: or matches the existing path */ if( !path || path[0]=='\0' || !strcmp(path, ":auto:") || (oldPath && !strncmp(oldPath, path, MAXPATHLEN)) ){ return SQLITE_OK; }else{ unixFile *lockProxy = pCtx->lockProxy; pCtx->lockProxy=NULL; pCtx->conchHeld = 0; if( lockProxy!=NULL ){ rc=lockProxy->pMethod->xClose((sqlite3_file *)lockProxy); if( rc ) return rc; sqlite3_free(lockProxy); } sqlite3_free(oldPath); pCtx->lockProxyPath = sqlite3DbStrDup(0, path); } return rc; } /* ** pFile is a file that has been opened by a prior xOpen call. dbPath ** is a string buffer at least MAXPATHLEN+1 characters in size. ** ** This routine find the filename associated with pFile and writes it ** int dbPath. */ static int proxyGetDbPathForUnixFile(unixFile *pFile, char *dbPath){ #if defined(__APPLE__) if( pFile->pMethod == &afpIoMethods ){ /* afp style keeps a reference to the db path in the filePath field ** of the struct */ assert( (int)strlen((char*)pFile->lockingContext)<=MAXPATHLEN ); strlcpy(dbPath, ((afpLockingContext *)pFile->lockingContext)->dbPath, MAXPATHLEN); } else #endif if( pFile->pMethod == &dotlockIoMethods ){ /* dot lock style uses the locking context to store the dot lock ** file path */ int len = strlen((char *)pFile->lockingContext) - strlen(DOTLOCK_SUFFIX); memcpy(dbPath, (char *)pFile->lockingContext, len + 1); }else{ /* all other styles use the locking context to store the db file path */ assert( strlen((char*)pFile->lockingContext)<=MAXPATHLEN ); strlcpy(dbPath, (char *)pFile->lockingContext, MAXPATHLEN); } return SQLITE_OK; } /* ** Takes an already filled in unix file and alters it so all file locking ** will be performed on the local proxy lock file. The following fields ** are preserved in the locking context so that they can be restored and ** the unix structure properly cleaned up at close time: ** ->lockingContext ** ->pMethod */ static int proxyTransformUnixFile(unixFile *pFile, const char *path) { proxyLockingContext *pCtx; char dbPath[MAXPATHLEN+1]; /* Name of the database file */ char *lockPath=NULL; int rc = SQLITE_OK; if( pFile->eFileLock!=NO_LOCK ){ return SQLITE_BUSY; } proxyGetDbPathForUnixFile(pFile, dbPath); if( !path || path[0]=='\0' || !strcmp(path, ":auto:") ){ lockPath=NULL; }else{ lockPath=(char *)path; } OSTRACE(("TRANSPROXY %d for %s pid=%d\n", pFile->h, (lockPath ? lockPath : ":auto:"), osGetpid(0))); pCtx = sqlite3_malloc64( sizeof(*pCtx) ); if( pCtx==0 ){ return SQLITE_NOMEM_BKPT; } memset(pCtx, 0, sizeof(*pCtx)); rc = proxyCreateConchPathname(dbPath, &pCtx->conchFilePath); if( rc==SQLITE_OK ){ rc = proxyCreateUnixFile(pCtx->conchFilePath, &pCtx->conchFile, 0); if( rc==SQLITE_CANTOPEN && ((pFile->openFlags&O_RDWR) == 0) ){ /* if (a) the open flags are not O_RDWR, (b) the conch isn't there, and ** (c) the file system is read-only, then enable no-locking access. ** Ugh, since O_RDONLY==0x0000 we test for !O_RDWR since unixOpen asserts ** that openFlags will have only one of O_RDONLY or O_RDWR. */ struct statfs fsInfo; struct stat conchInfo; int goLockless = 0; if( osStat(pCtx->conchFilePath, &conchInfo) == -1 ) { int err = errno; if( (err==ENOENT) && (statfs(dbPath, &fsInfo) != -1) ){ goLockless = (fsInfo.f_flags&MNT_RDONLY) == MNT_RDONLY; } } if( goLockless ){ pCtx->conchHeld = -1; /* read only FS/ lockless */ rc = SQLITE_OK; } } } if( rc==SQLITE_OK && lockPath ){ pCtx->lockProxyPath = sqlite3DbStrDup(0, lockPath); } if( rc==SQLITE_OK ){ pCtx->dbPath = sqlite3DbStrDup(0, dbPath); if( pCtx->dbPath==NULL ){ rc = SQLITE_NOMEM_BKPT; } } if( rc==SQLITE_OK ){ /* all memory is allocated, proxys are created and assigned, ** switch the locking context and pMethod then return. */ pCtx->oldLockingContext = pFile->lockingContext; pFile->lockingContext = pCtx; pCtx->pOldMethod = pFile->pMethod; pFile->pMethod = &proxyIoMethods; }else{ if( pCtx->conchFile ){ pCtx->conchFile->pMethod->xClose((sqlite3_file *)pCtx->conchFile); sqlite3_free(pCtx->conchFile); } sqlite3DbFree(0, pCtx->lockProxyPath); sqlite3_free(pCtx->conchFilePath); sqlite3_free(pCtx); } OSTRACE(("TRANSPROXY %d %s\n", pFile->h, (rc==SQLITE_OK ? "ok" : "failed"))); return rc; } /* ** This routine handles sqlite3_file_control() calls that are specific ** to proxy locking. */ static int proxyFileControl(sqlite3_file *id, int op, void *pArg){ switch( op ){ case SQLITE_FCNTL_GET_LOCKPROXYFILE: { unixFile *pFile = (unixFile*)id; if( pFile->pMethod == &proxyIoMethods ){ proxyLockingContext *pCtx = (proxyLockingContext*)pFile->lockingContext; proxyTakeConch(pFile); if( pCtx->lockProxyPath ){ *(const char **)pArg = pCtx->lockProxyPath; }else{ *(const char **)pArg = ":auto: (not held)"; } } else { *(const char **)pArg = NULL; } return SQLITE_OK; } case SQLITE_FCNTL_SET_LOCKPROXYFILE: { unixFile *pFile = (unixFile*)id; int rc = SQLITE_OK; int isProxyStyle = (pFile->pMethod == &proxyIoMethods); if( pArg==NULL || (const char *)pArg==0 ){ if( isProxyStyle ){ /* turn off proxy locking - not supported. If support is added for ** switching proxy locking mode off then it will need to fail if ** the journal mode is WAL mode. */ rc = SQLITE_ERROR /*SQLITE_PROTOCOL? SQLITE_MISUSE?*/; }else{ /* turn off proxy locking - already off - NOOP */ rc = SQLITE_OK; } }else{ const char *proxyPath = (const char *)pArg; if( isProxyStyle ){ proxyLockingContext *pCtx = (proxyLockingContext*)pFile->lockingContext; if( !strcmp(pArg, ":auto:") || (pCtx->lockProxyPath && !strncmp(pCtx->lockProxyPath, proxyPath, MAXPATHLEN)) ){ rc = SQLITE_OK; }else{ rc = switchLockProxyPath(pFile, proxyPath); } }else{ /* turn on proxy file locking */ rc = proxyTransformUnixFile(pFile, proxyPath); } } return rc; } default: { assert( 0 ); /* The call assures that only valid opcodes are sent */ } } /*NOTREACHED*/ assert(0); return SQLITE_ERROR; } /* ** Within this division (the proxying locking implementation) the procedures ** above this point are all utilities. The lock-related methods of the ** proxy-locking sqlite3_io_method object follow. */ /* ** This routine checks if there is a RESERVED lock held on the specified ** file by this or any other process. If such a lock is held, set *pResOut ** to a non-zero value otherwise *pResOut is set to zero. The return value ** is set to SQLITE_OK unless an I/O error occurs during lock checking. */ static int proxyCheckReservedLock(sqlite3_file *id, int *pResOut) { unixFile *pFile = (unixFile*)id; int rc = proxyTakeConch(pFile); if( rc==SQLITE_OK ){ proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; if( pCtx->conchHeld>0 ){ unixFile *proxy = pCtx->lockProxy; return proxy->pMethod->xCheckReservedLock((sqlite3_file*)proxy, pResOut); }else{ /* conchHeld < 0 is lockless */ pResOut=0; } } return rc; } /* ** Lock the file with the lock specified by parameter eFileLock - one ** of the following: ** ** (1) SHARED_LOCK ** (2) RESERVED_LOCK ** (3) PENDING_LOCK ** (4) EXCLUSIVE_LOCK ** ** Sometimes when requesting one lock state, additional lock states ** are inserted in between. The locking might fail on one of the later ** transitions leaving the lock state different from what it started but ** still short of its goal. The following chart shows the allowed ** transitions and the inserted intermediate states: ** ** UNLOCKED -> SHARED ** SHARED -> RESERVED ** SHARED -> (PENDING) -> EXCLUSIVE ** RESERVED -> (PENDING) -> EXCLUSIVE ** PENDING -> EXCLUSIVE ** ** This routine will only increase a lock. Use the sqlite3OsUnlock() ** routine to lower a locking level. */ static int proxyLock(sqlite3_file *id, int eFileLock) { unixFile *pFile = (unixFile*)id; int rc = proxyTakeConch(pFile); if( rc==SQLITE_OK ){ proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; if( pCtx->conchHeld>0 ){ unixFile *proxy = pCtx->lockProxy; rc = proxy->pMethod->xLock((sqlite3_file*)proxy, eFileLock); pFile->eFileLock = proxy->eFileLock; }else{ /* conchHeld < 0 is lockless */ } } return rc; } /* ** Lower the locking level on file descriptor pFile to eFileLock. eFileLock ** must be either NO_LOCK or SHARED_LOCK. ** ** If the locking level of the file descriptor is already at or below ** the requested locking level, this routine is a no-op. */ static int proxyUnlock(sqlite3_file *id, int eFileLock) { unixFile *pFile = (unixFile*)id; int rc = proxyTakeConch(pFile); if( rc==SQLITE_OK ){ proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; if( pCtx->conchHeld>0 ){ unixFile *proxy = pCtx->lockProxy; rc = proxy->pMethod->xUnlock((sqlite3_file*)proxy, eFileLock); pFile->eFileLock = proxy->eFileLock; }else{ /* conchHeld < 0 is lockless */ } } return rc; } /* ** Close a file that uses proxy locks. */ static int proxyClose(sqlite3_file *id) { if( ALWAYS(id) ){ unixFile *pFile = (unixFile*)id; proxyLockingContext *pCtx = (proxyLockingContext *)pFile->lockingContext; unixFile *lockProxy = pCtx->lockProxy; unixFile *conchFile = pCtx->conchFile; int rc = SQLITE_OK; if( lockProxy ){ rc = lockProxy->pMethod->xUnlock((sqlite3_file*)lockProxy, NO_LOCK); if( rc ) return rc; rc = lockProxy->pMethod->xClose((sqlite3_file*)lockProxy); if( rc ) return rc; sqlite3_free(lockProxy); pCtx->lockProxy = 0; } if( conchFile ){ if( pCtx->conchHeld ){ rc = proxyReleaseConch(pFile); if( rc ) return rc; } rc = conchFile->pMethod->xClose((sqlite3_file*)conchFile); if( rc ) return rc; sqlite3_free(conchFile); } sqlite3DbFree(0, pCtx->lockProxyPath); sqlite3_free(pCtx->conchFilePath); sqlite3DbFree(0, pCtx->dbPath); /* restore the original locking context and pMethod then close it */ pFile->lockingContext = pCtx->oldLockingContext; pFile->pMethod = pCtx->pOldMethod; sqlite3_free(pCtx); return pFile->pMethod->xClose(id); } return SQLITE_OK; } #endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */ /* ** The proxy locking style is intended for use with AFP filesystems. ** And since AFP is only supported on MacOSX, the proxy locking is also ** restricted to MacOSX. ** ** ******************* End of the proxy lock implementation ********************** ******************************************************************************/ /* ** Initialize the operating system interface. ** ** This routine registers all VFS implementations for unix-like operating ** systems. This routine, and the sqlite3_os_end() routine that follows, ** should be the only routines in this file that are visible from other ** files. ** ** This routine is called once during SQLite initialization and by a ** single thread. The memory allocation and mutex subsystems have not ** necessarily been initialized when this routine is called, and so they ** should not be used. */ int sqlite3_os_init(void){ /* ** The following macro defines an initializer for an sqlite3_vfs object. ** The name of the VFS is NAME. The pAppData is a pointer to a pointer ** to the "finder" function. (pAppData is a pointer to a pointer because ** silly C90 rules prohibit a void* from being cast to a function pointer ** and so we have to go through the intermediate pointer to avoid problems ** when compiling with -pedantic-errors on GCC.) ** ** The FINDER parameter to this macro is the name of the pointer to the ** finder-function. The finder-function returns a pointer to the ** sqlite_io_methods object that implements the desired locking ** behaviors. See the division above that contains the IOMETHODS ** macro for addition information on finder-functions. ** ** Most finders simply return a pointer to a fixed sqlite3_io_methods ** object. But the "autolockIoFinder" available on MacOSX does a little ** more than that; it looks at the filesystem type that hosts the ** database file and tries to choose an locking method appropriate for ** that filesystem time. */ #define UNIXVFS(VFSNAME, FINDER) { \ 3, /* iVersion */ \ sizeof(unixFile), /* szOsFile */ \ MAX_PATHNAME, /* mxPathname */ \ 0, /* pNext */ \ VFSNAME, /* zName */ \ (void*)&FINDER, /* pAppData */ \ unixOpen, /* xOpen */ \ unixDelete, /* xDelete */ \ unixAccess, /* xAccess */ \ unixFullPathname, /* xFullPathname */ \ unixDlOpen, /* xDlOpen */ \ unixDlError, /* xDlError */ \ unixDlSym, /* xDlSym */ \ unixDlClose, /* xDlClose */ \ unixRandomness, /* xRandomness */ \ unixSleep, /* xSleep */ \ unixCurrentTime, /* xCurrentTime */ \ unixGetLastError, /* xGetLastError */ \ unixCurrentTimeInt64, /* xCurrentTimeInt64 */ \ unixSetSystemCall, /* xSetSystemCall */ \ unixGetSystemCall, /* xGetSystemCall */ \ unixNextSystemCall, /* xNextSystemCall */ \ } /* ** All default VFSes for unix are contained in the following array. ** ** Note that the sqlite3_vfs.pNext field of the VFS object is modified ** by the SQLite core when the VFS is registered. So the following ** array cannot be const. */ static sqlite3_vfs aVfs[] = { #if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__) UNIXVFS("unix", autolockIoFinder ), #elif OS_VXWORKS UNIXVFS("unix", vxworksIoFinder ), #else UNIXVFS("unix", posixIoFinder ), #endif UNIXVFS("unix-none", nolockIoFinder ), UNIXVFS("unix-dotfile", dotlockIoFinder ), UNIXVFS("unix-excl", posixIoFinder ), #if OS_VXWORKS UNIXVFS("unix-namedsem", semIoFinder ), #endif #if SQLITE_ENABLE_LOCKING_STYLE || OS_VXWORKS UNIXVFS("unix-posix", posixIoFinder ), #endif #if SQLITE_ENABLE_LOCKING_STYLE UNIXVFS("unix-flock", flockIoFinder ), #endif #if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__) UNIXVFS("unix-afp", afpIoFinder ), UNIXVFS("unix-nfs", nfsIoFinder ), UNIXVFS("unix-proxy", proxyIoFinder ), #endif }; unsigned int i; /* Loop counter */ /* Double-check that the aSyscall[] array has been constructed ** correctly. See ticket [bb3a86e890c8e96ab] */ assert( ArraySize(aSyscall)==29 ); /* Register all VFSes defined in the aVfs[] array */ for(i=0; i<(sizeof(aVfs)/sizeof(sqlite3_vfs)); i++){ #ifdef SQLITE_DEFAULT_UNIX_VFS sqlite3_vfs_register(&aVfs[i], 0==strcmp(aVfs[i].zName,SQLITE_DEFAULT_UNIX_VFS)); #else sqlite3_vfs_register(&aVfs[i], i==0); #endif } #ifdef SQLITE_OS_KV_OPTIONAL sqlite3KvvfsInit(); #endif unixBigLock = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_VFS1); #if OS_VXWORKS vxworksMutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_VFS2); #endif #ifndef SQLITE_OMIT_WAL /* Validate lock assumptions */ assert( SQLITE_SHM_NLOCK==8 ); /* Number of available locks */ assert( UNIX_SHM_BASE==120 ); /* Start of locking area */ /* Locks: ** WRITE UNIX_SHM_BASE 120 ** CKPT UNIX_SHM_BASE+1 121 ** RECOVER UNIX_SHM_BASE+2 122 ** READ-0 UNIX_SHM_BASE+3 123 ** READ-1 UNIX_SHM_BASE+4 124 ** READ-2 UNIX_SHM_BASE+5 125 ** READ-3 UNIX_SHM_BASE+6 126 ** READ-4 UNIX_SHM_BASE+7 127 ** DMS UNIX_SHM_BASE+8 128 */ assert( UNIX_SHM_DMS==128 ); /* Byte offset of the deadman-switch */ #endif return SQLITE_OK; } /* ** Shutdown the operating system interface. ** ** Some operating systems might need to do some cleanup in this routine, ** to release dynamically allocated objects. But not on unix. ** This routine is a no-op for unix. */ int sqlite3_os_end(void){ unixBigLock = 0; #if OS_VXWORKS vxworksMutex = 0; #endif return SQLITE_OK; } #endif /* SQLITE_OS_UNIX */