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main
lib/system.h
364 строки
9 KB
Mark Wielaard
elfcompress: Handle existing output files (symlinks)
19 июн 2026, 01:53
19 июн 2026, 01:53
0e8b57a
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/* Declarations for common convenience functions. Copyright (C) 2006-2011 Red Hat, Inc. Copyright (C) 2022, 2026 Mark J. Wielaard <mark@klomp.org> Copyright (C) 2023 Khem Raj. This file is part of elfutils. This file is free software; you can redistribute it and/or modify it under the terms of either * the GNU Lesser General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version or * the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version or both in parallel, as here. elfutils is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received copies of the GNU General Public License and the GNU Lesser General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ #ifndef LIB_SYSTEM_H #define LIB_SYSTEM_H 1 /* Prevent double inclusion of config.h, config.h includes eu-config.h. */ #ifdef HAVE_CONFIG_H #ifndef EU_CONFIG_H # include <config.h> #endif #endif #include <errno.h> #include <fcntl.h> #include <stdbool.h> #include <stddef.h> #include <stdint.h> #include <string.h> #include <stdarg.h> #include <stdlib.h> /* System dependent headers */ #include <byteswap.h> #include <endian.h> #include <sys/mman.h> #include <sys/param.h> #include <unistd.h> #if defined(HAVE_SYS_RANDOM_H) #include <sys/random.h> #endif #if defined(HAVE_ERROR_H) #include <error.h> #elif defined(HAVE_ERR_H) extern int error_message_count; void error(int status, int errnum, const char *format, ...); #else #error "err.h or error.h must be available" #endif /* error (EXIT_FAILURE, ...) should be noreturn but on some systems it isn't. This may cause warnings about code that should not be reachable. So have an explicit error_exit wrapper that is noreturn (because it calls exit explicitly). */ #define error_exit(errnum,...) do { \ error (EXIT_FAILURE,errnum,__VA_ARGS__); \ exit (EXIT_FAILURE); \ } while (0) #if BYTE_ORDER == LITTLE_ENDIAN # define LE32(n) (n) # define LE64(n) (n) # define BE32(n) bswap_32 (n) # define BE64(n) bswap_64 (n) #elif BYTE_ORDER == BIG_ENDIAN # define BE32(n) (n) # define BE64(n) (n) # define LE32(n) bswap_32 (n) # define LE64(n) bswap_64 (n) #else # error "Unknown byte order" #endif #ifndef MAX #define MAX(m, n) ((m) < (n) ? (n) : (m)) #endif #ifndef MIN #define MIN(m, n) ((m) < (n) ? (m) : (n)) #endif #if !HAVE_DECL_POWEROF2 #define powerof2(x) (((x) & ((x) - 1)) == 0) #endif #if !HAVE_DECL_MEMPCPY #define mempcpy(dest, src, n) \ ((void *) ((char *) memcpy (dest, src, n) + (size_t) n)) #endif #if !HAVE_DECL_REALLOCARRAY static inline void * reallocarray (void *ptr, size_t nmemb, size_t size) { if (size > 0 && nmemb > SIZE_MAX / size) { errno = ENOMEM; return NULL; } return realloc (ptr, nmemb * size); } #endif /* Return TRUE if the start of STR matches PREFIX, FALSE otherwise. */ static inline int startswith (const char *str, const char *prefix) { return strncmp (str, prefix, strlen (prefix)) == 0; } /* Return TRUE if STR[FROM] is a valid string with a zero terminator at or before STR[TO - 1]. Note FROM is an index into the STR array, while TO is the maximum size of the STR array. This function returns FALSE when TO is zero or FROM >= TO. */ static inline bool validate_str (const char *str, size_t from, size_t to) { #if HAVE_DECL_MEMRCHR // Check end first, which is likely a zero terminator, // to prevent function call return (to > 0 && (str[to - 1] == '\0' || (to > from && memrchr (&str[from], '\0', to - from - 1) != NULL))); #else do { if (to <= from) return false; to--; } while (str[to]); return true; #endif } /* A special gettext function we use if the strings are too short. */ #define sgettext(Str) \ ({ const char *__res = strrchr (_(Str), '|'); \ __res ? __res + 1 : Str; }) #define gettext_noop(Str) Str #ifndef TEMP_FAILURE_RETRY #define TEMP_FAILURE_RETRY(expression) \ ({ ssize_t __res; \ do \ __res = expression; \ while (__res == -1 && errno == EINTR); \ __res; }) #endif #ifndef ACCESSPERMS #define ACCESSPERMS (S_IRWXU|S_IRWXG|S_IRWXO) /* 0777 */ #endif #ifndef ALLPERMS #define ALLPERMS (S_ISUID|S_ISGID|S_ISVTX|S_IRWXU|S_IRWXG|S_IRWXO) /* 07777 */ #endif #ifndef DEFFILEMODE #define DEFFILEMODE (S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH)/* 0666 */ #endif static inline ssize_t __attribute__ ((unused)) pwrite_retry (int fd, const void *buf, size_t len, off_t off) { ssize_t recvd = 0; do { ssize_t ret = TEMP_FAILURE_RETRY (pwrite (fd, ((char *)buf) + recvd, len - recvd, off + recvd)); if (ret <= 0) return ret < 0 ? ret : recvd; recvd += ret; } while ((size_t) recvd < len); return recvd; } static inline ssize_t __attribute__ ((unused)) write_retry (int fd, const void *buf, size_t len) { ssize_t recvd = 0; do { ssize_t ret = TEMP_FAILURE_RETRY (write (fd, ((char *)buf) + recvd, len - recvd)); if (ret <= 0) return ret < 0 ? ret : recvd; recvd += ret; } while ((size_t) recvd < len); return recvd; } static inline ssize_t __attribute__ ((unused)) pread_retry (int fd, void *buf, size_t len, off_t off) { ssize_t recvd = 0; do { ssize_t ret = TEMP_FAILURE_RETRY (pread (fd, ((char *)buf) + recvd, len - recvd, off + recvd)); if (ret <= 0) return ret < 0 ? ret : recvd; recvd += ret; } while ((size_t) recvd < len); return recvd; } static inline ssize_t __attribute__ ((unused)) read_retry (int fd, void *buf, size_t len) { ssize_t recvd = 0; do { ssize_t ret = TEMP_FAILURE_RETRY (read (fd, ((char *)buf) + recvd, len - recvd)); if (ret <= 0) return ret < 0 ? ret : recvd; recvd += ret; } while ((size_t) recvd < len); return recvd; } /* The demangler from libstdc++. */ extern char *__cxa_demangle (const char *mangled_name, char *output_buffer, size_t *length, int *status); /* A static assertion. This will cause a compile-time error if EXPR, which must be a compile-time constant, is false. */ #define eu_static_assert(expr) \ extern int never_defined_just_used_for_checking[(expr) ? 1 : -1] \ __attribute__ ((unused)) /* We really want a basename implementation that doesn't modify the input argument. Normally you get that from string.h with _GNU_SOURCE define. But some libc implementations don't define it and other define it, but provide an implementation that still modifies the argument. So define our own and poison a bare basename symbol. */ static inline const char * xbasename(const char *s) { const char *p = strrchr(s, '/'); return p ? p+1 : s; } #pragma GCC poison basename /* Get a random uint64_t. Returns zero on success, minus one on failure. */ static inline int xrandom64 (uint64_t *r) { /* Prefer getentropy if it is available, fallback to getrandom, if both are missing, or if they fail try reading from /dev/urandom. */ #if HAVE_DECL_GETENTROPY if (getentropy (r, sizeof (*r)) == 0) return 0; #elif HAVE_DECL_GETRANDOM if (TEMP_FAILURE_RETRY (getrandom (r, sizeof (*r), 0)) == sizeof (*r)) return 0; #endif int fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC); if (fd < 0) return -1; if (read_retry (fd, r, sizeof (uint64_t)) == sizeof (uint64_t)) { close (fd); return 0; } int save_errno = errno; close (fd); errno = save_errno; /* We could try some pseudo-random thing with getpid and clock_gettime. But if even getting something from /dev/urandom fails it seems we tried hard enough already. */ return -1; } /* There is no mkstempat needed for creating a temp file in a specific directory. Needed e.g. in combination with renameat to atomicly replace a file. So define one ourselves. Like mkstemp the template must end in "XXXXXX", which are replaced by an unique filename suffix. The file is created with user read/write permissions only in the given dirfd using openat. https://sourceware.org/bugzilla/show_bug.cgi?id=19866 */ static inline int xmkstempat (int dirfd, char *templ) { /* Only use these 64 chars. */ const char chars[] = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-_"; /* Must end in 6X. */ size_t l = strlen (templ); if (l < 6 || memcmp (templ + l - 6, "XXXXXX", 6) != 0) { errno = EINVAL; return -1; } int tries = 128; /* Just fail with EEXIST if 128 tries wasn't enough. */ do { uint64_t r; /* We need at least 64^6 == 2^36 */ if (xrandom64 (&r) != 0) return -1; /* Random chars for the template. */ for (int i = 0; i < 6; i++) { templ[l - 6 + i] = chars[r % 64]; r /= 64; } /* Must be able to open exclusively. */ int fd = openat (dirfd, templ, O_RDWR | O_CREAT | O_EXCL | O_CLOEXEC, S_IRUSR | S_IWUSR); if (fd >= 0) return fd; tries--; } while (tries > 0 && errno == EEXIST); return -1; } #endif /* system.h */