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v260
src/basic/fileio.c
1 657 строк
54 KB
Yu Watanabe
tree-wide: normalize comment style
15 дек 2025, 02:50
15 дек 2025, 02:50
9337814
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/* SPDX-License-Identifier: LGPL-2.1-or-later */ #include <fcntl.h> #include <stdio_ext.h> #include <stdlib.h> #include <sys/stat.h> #include <unistd.h> #include "alloc-util.h" #include "errno-util.h" #include "extract-word.h" #include "fd-util.h" #include "fileio.h" #include "fs-util.h" #include "hexdecoct.h" #include "label.h" #include "log.h" #include "mkdir.h" #include "nulstr-util.h" #include "parse-util.h" #include "path-util.h" #include "socket-util.h" #include "stat-util.h" #include "stdio-util.h" #include "string-util.h" #include "strv.h" #include "sync-util.h" #include "terminal-util.h" #include "time-util.h" #include "tmpfile-util.h" /* The maximum size of the file we'll read in one go in read_full_file() (64M). */ #define READ_FULL_BYTES_MAX (64U * U64_MB - UINT64_C(1)) /* Used when a size is specified for read_full_file() with READ_FULL_FILE_UNBASE64 or _UNHEX */ #define READ_FULL_FILE_ENCODED_STRING_AMPLIFICATION_BOUNDARY 3 /* The maximum size of virtual files (i.e. procfs, sysfs, and other virtual "API" files) we'll read in one go * in read_virtual_file(). Note that this limit is different (and much lower) than the READ_FULL_BYTES_MAX * limit. This reflects the fact that we use different strategies for reading virtual and regular files: * virtual files we generally have to read in a single read() syscall since the kernel doesn't support * continuation read()s for them. Thankfully they are somewhat size constrained. Thus we can allocate the * full potential buffer in advance. Regular files OTOH can be much larger, and there we grow the allocations * exponentially in a loop. We use a size limit of 4M-2 because 4M-1 is the maximum buffer that /proc/sys/ * allows us to read() (larger reads will fail with ENOMEM), and we want to read one extra byte so that we * can detect EOFs. */ #define READ_VIRTUAL_BYTES_MAX (4U * U64_MB - UINT64_C(2)) int fdopen_unlocked(int fd, const char *options, FILE **ret) { assert(ret); FILE *f = fdopen(fd, options); if (!f) return -errno; (void) __fsetlocking(f, FSETLOCKING_BYCALLER); *ret = f; return 0; } int take_fdopen_unlocked(int *fd, const char *options, FILE **ret) { int r; assert(fd); r = fdopen_unlocked(*fd, options, ret); if (r < 0) return r; *fd = -EBADF; return 0; } FILE* take_fdopen(int *fd, const char *options) { assert(fd); FILE *f = fdopen(*fd, options); if (!f) return NULL; *fd = -EBADF; return f; } DIR* take_fdopendir(int *dfd) { assert(dfd); DIR *d = fdopendir(*dfd); if (!d) return NULL; *dfd = -EBADF; return d; } FILE* open_memstream_unlocked(char **ptr, size_t *sizeloc) { FILE *f = open_memstream(ptr, sizeloc); if (!f) return NULL; (void) __fsetlocking(f, FSETLOCKING_BYCALLER); return f; } FILE* fmemopen_unlocked(void *buf, size_t size, const char *mode) { FILE *f = fmemopen(buf, size, mode); if (!f) return NULL; (void) __fsetlocking(f, FSETLOCKING_BYCALLER); return f; } int write_string_stream_full( FILE *f, const char *line, WriteStringFileFlags flags, const struct timespec *ts) { bool needs_nl; int r, fd = -EBADF; assert(f); assert(line); if (ferror(f)) return -EIO; if (ts) { /* If we shall set the timestamp we need the fd. But fmemopen() streams generally don't have * an fd. Let's fail early in that case. */ fd = fileno(f); if (fd < 0) return -EBADF; } if (flags & WRITE_STRING_FILE_SUPPRESS_REDUNDANT_VIRTUAL) { _cleanup_free_ char *t = NULL; /* If value to be written is same as that of the existing value, then suppress the write. */ if (fd < 0) { fd = fileno(f); if (fd < 0) return -EBADF; } /* Read an additional byte to detect cases where the prefix matches but the rest * doesn't. Also, 0 returned by read_virtual_file_fd() means the read was truncated and * it won't be equal to the new value. */ if (read_virtual_file_fd(fd, strlen(line)+1, &t, NULL) > 0 && streq_skip_trailing_chars(line, t, NEWLINE)) { log_debug("No change in value '%s', suppressing write", line); return 0; } if (lseek(fd, 0, SEEK_SET) < 0) return -errno; } needs_nl = !(flags & WRITE_STRING_FILE_AVOID_NEWLINE) && !endswith(line, "\n"); if (needs_nl && (flags & WRITE_STRING_FILE_DISABLE_BUFFER)) { /* If STDIO buffering was disabled, then let's append the newline character to the string * itself, so that the write goes out in one go, instead of two */ line = strjoina(line, "\n"); needs_nl = false; } if (fputs(line, f) == EOF) return -errno; if (needs_nl) if (fputc('\n', f) == EOF) return -errno; if (flags & WRITE_STRING_FILE_SYNC) r = fflush_sync_and_check(f); else r = fflush_and_check(f); if (r < 0) return r; if (ts) { const struct timespec twice[2] = {*ts, *ts}; assert(fd >= 0); if (futimens(fd, twice) < 0) return -errno; } return 0; } static mode_t write_string_file_flags_to_mode(WriteStringFileFlags flags) { /* We support three different modes, that are the ones that really make sense for text files like this: * * → 0600 (i.e. root-only) * → 0444 (i.e. read-only) * → 0644 (i.e. writable for root, readable for everyone else) */ return FLAGS_SET(flags, WRITE_STRING_FILE_MODE_0600) ? 0600 : FLAGS_SET(flags, WRITE_STRING_FILE_MODE_0444) ? 0444 : 0644; } static int write_string_file_atomic_at( int dir_fd, const char *fn, const char *line, WriteStringFileFlags flags, const struct timespec *ts) { _cleanup_fclose_ FILE *f = NULL; _cleanup_free_ char *p = NULL; int r; assert(fn); assert(line); /* Note that we'd really like to use O_TMPFILE here, but can't really, since we want replacement * semantics here, and O_TMPFILE can't offer that. i.e. rename() replaces but linkat() doesn't. */ mode_t mode = write_string_file_flags_to_mode(flags); bool call_label_ops_post = false; if (FLAGS_SET(flags, WRITE_STRING_FILE_LABEL)) { r = label_ops_pre(dir_fd, fn, mode); if (r < 0) return r; call_label_ops_post = true; } r = fopen_temporary_at(dir_fd, fn, &f, &p); int k = call_label_ops_post ? label_ops_post(f ? fileno(f) : dir_fd, f ? NULL : fn, /* created= */ !!f) : 0; /* If fopen_temporary_at() failed in the above, propagate the error code, and ignore failures in * label_ops_post(). */ if (r < 0) return r; CLEANUP_TMPFILE_AT(dir_fd, p); if (k < 0) return k; r = write_string_stream_full(f, line, flags, ts); if (r < 0) return r; r = fchmod_umask(fileno(f), mode); if (r < 0) return r; r = RET_NERRNO(renameat(dir_fd, p, dir_fd, fn)); if (r < 0) return r; p = mfree(p); /* disarm CLEANUP_TMPFILE_AT() */ if (FLAGS_SET(flags, WRITE_STRING_FILE_SYNC)) { /* Sync the rename, too */ r = fsync_directory_of_file(fileno(f)); if (r < 0) return r; } return 0; } int write_string_file_full( int dir_fd, const char *fn, const char *line, WriteStringFileFlags flags, const struct timespec *ts, const char *label_fn) { bool made_file = false; _cleanup_fclose_ FILE *f = NULL; _cleanup_close_ int fd = -EBADF; int r; assert(dir_fd == AT_FDCWD || dir_fd >= 0); assert(line); /* We don't know how to verify whether the file contents was already on-disk. */ assert(!((flags & WRITE_STRING_FILE_VERIFY_ON_FAILURE) && (flags & WRITE_STRING_FILE_SYNC))); if (flags & WRITE_STRING_FILE_MKDIR_0755) { assert(fn); r = mkdirat_parents(dir_fd, fn, 0755); if (r < 0) return r; } if (flags & WRITE_STRING_FILE_ATOMIC) { assert(fn); assert(flags & WRITE_STRING_FILE_CREATE); r = write_string_file_atomic_at(dir_fd, fn, line, flags, ts); if (r < 0) goto fail; return r; } /* We manually build our own version of fopen(..., "we") that works without O_CREAT and with O_NOFOLLOW if needed. */ if (isempty(fn)) r = fd = fd_reopen( ASSERT_FD(dir_fd), O_CLOEXEC | O_NOCTTY | (FLAGS_SET(flags, WRITE_STRING_FILE_TRUNCATE) ? O_TRUNC : 0) | (FLAGS_SET(flags, WRITE_STRING_FILE_SUPPRESS_REDUNDANT_VIRTUAL) ? O_RDWR : O_WRONLY) | (FLAGS_SET(flags, WRITE_STRING_FILE_OPEN_NONBLOCKING) ? O_NONBLOCK : 0)); else { mode_t mode = write_string_file_flags_to_mode(flags); bool call_label_ops_post = false; if (FLAGS_SET(flags, WRITE_STRING_FILE_LABEL|WRITE_STRING_FILE_CREATE)) { r = label_ops_pre(dir_fd, label_fn ?: fn, mode); if (r < 0) goto fail; call_label_ops_post = true; } r = fd = openat_report_new( dir_fd, fn, O_CLOEXEC | O_NOCTTY | (FLAGS_SET(flags, WRITE_STRING_FILE_NOFOLLOW) ? O_NOFOLLOW : 0) | (FLAGS_SET(flags, WRITE_STRING_FILE_CREATE) ? O_CREAT : 0) | (FLAGS_SET(flags, WRITE_STRING_FILE_TRUNCATE) ? O_TRUNC : 0) | (FLAGS_SET(flags, WRITE_STRING_FILE_SUPPRESS_REDUNDANT_VIRTUAL) ? O_RDWR : O_WRONLY) | (FLAGS_SET(flags, WRITE_STRING_FILE_OPEN_NONBLOCKING) ? O_NONBLOCK : 0), mode, &made_file); if (call_label_ops_post) /* If openat_report_new() failed in the above, propagate the error code, and ignore * failures in label_ops_post(). */ RET_GATHER(r, label_ops_post(fd >= 0 ? fd : dir_fd, fd >= 0 ? NULL : fn, made_file)); } if (r < 0) goto fail; r = take_fdopen_unlocked(&fd, "w", &f); if (r < 0) goto fail; if (flags & WRITE_STRING_FILE_DISABLE_BUFFER) setvbuf(f, NULL, _IONBF, 0); r = write_string_stream_full(f, line, flags, ts); if (r < 0) goto fail; return 0; fail: if (made_file) (void) unlinkat(dir_fd, fn, 0); if (!(flags & WRITE_STRING_FILE_VERIFY_ON_FAILURE)) return r; f = safe_fclose(f); fd = safe_close(fd); /* OK, the operation failed, but let's see if the right contents in place already. If so, eat up the * error. */ if (verify_file_at(dir_fd, fn, line, !(flags & WRITE_STRING_FILE_AVOID_NEWLINE) || (flags & WRITE_STRING_FILE_VERIFY_IGNORE_NEWLINE)) > 0) return 0; return r; } int write_string_filef( const char *fn, WriteStringFileFlags flags, const char *format, ...) { _cleanup_free_ char *p = NULL; va_list ap; int r; va_start(ap, format); r = vasprintf(&p, format, ap); va_end(ap); if (r < 0) return -ENOMEM; return write_string_file(fn, p, flags); } int write_base64_file_at( int dir_fd, const char *fn, const struct iovec *data, WriteStringFileFlags flags) { _cleanup_free_ char *encoded = NULL; ssize_t n; n = base64mem_full(data ? data->iov_base : NULL, data ? data->iov_len : 0, 79, &encoded); if (n < 0) return n; return write_string_file_at(dir_fd, fn, encoded, flags); } int read_one_line_file_at(int dir_fd, const char *filename, char **ret) { _cleanup_fclose_ FILE *f = NULL; int r; assert(dir_fd >= 0 || dir_fd == AT_FDCWD); assert(filename); assert(ret); r = fopen_unlocked_at(dir_fd, filename, "re", 0, &f); if (r < 0) return r; return read_line(f, LONG_LINE_MAX, ret); } int verify_file_at(int dir_fd, const char *fn, const char *blob, bool accept_extra_nl) { _cleanup_fclose_ FILE *f = NULL; _cleanup_free_ char *buf = NULL; size_t l, k; int r; assert(blob); l = strlen(blob); if (accept_extra_nl && endswith(blob, "\n")) accept_extra_nl = false; buf = malloc(l + accept_extra_nl + 1); if (!buf) return -ENOMEM; r = fopen_unlocked_at(dir_fd, strempty(fn), "re", 0, &f); if (r < 0) return r; /* We try to read one byte more than we need, so that we know whether we hit eof */ errno = 0; k = fread(buf, 1, l + accept_extra_nl + 1, f); if (ferror(f)) return errno_or_else(EIO); if (k != l && k != l + accept_extra_nl) return 0; if (memcmp(buf, blob, l) != 0) return 0; if (k > l && buf[l] != '\n') return 0; return 1; } int read_virtual_file_at( int dir_fd, const char *filename, size_t max_size, char **ret_contents, size_t *ret_size) { _cleanup_free_ char *buf = NULL; size_t n, size; int n_retries; bool truncated = false; /* Virtual filesystems such as sysfs or procfs use kernfs, and kernfs can work with two sorts of * virtual files. One sort uses "seq_file", and the results of the first read are buffered for the * second read. The other sort uses "raw" reads which always go direct to the device. In the latter * case, the content of the virtual file must be retrieved with a single read otherwise a second read * might get the new value instead of finding EOF immediately. That's the reason why the usage of * fread(3) is prohibited in this case as it always performs a second call to read(2) looking for * EOF. See issue #13585. * * max_size specifies a limit on the bytes read. If max_size is SIZE_MAX, the full file is read. If * the full file is too large to read, an error is returned. For other values of max_size, *partial * contents* may be returned. (Though the read is still done using one syscall.) Returns 0 on * partial success, 1 if untruncated contents were read. * * Rule: for kernfs files using "seq_file" → use regular read_full_file_at() * for kernfs files using "raw" → use read_virtual_file_at() */ assert(dir_fd >= 0 || dir_fd == AT_FDCWD); assert(max_size <= READ_VIRTUAL_BYTES_MAX || max_size == SIZE_MAX); _cleanup_close_ int fd = -EBADF; if (isempty(filename)) fd = fd_reopen(ASSERT_FD(dir_fd), O_RDONLY | O_NOCTTY | O_CLOEXEC); else fd = RET_NERRNO(openat(dir_fd, filename, O_RDONLY | O_NOCTTY | O_CLOEXEC)); if (fd < 0) return fd; /* Limit the number of attempts to read the number of bytes returned by fstat(). */ n_retries = 3; for (;;) { struct stat st; if (fstat(fd, &st) < 0) return -errno; if (!S_ISREG(st.st_mode)) return -EBADF; /* Be prepared for files from /proc which generally report a file size of 0. */ assert_cc(READ_VIRTUAL_BYTES_MAX < SSIZE_MAX); if (st.st_size > 0 && n_retries > 1) { /* Let's use the file size if we have more than 1 attempt left. On the last attempt * we'll ignore the file size */ if (st.st_size > SSIZE_MAX) { /* Avoid overflow with 32-bit size_t and 64-bit off_t. */ if (max_size == SIZE_MAX) return -EFBIG; size = max_size; } else { size = MIN((size_t) st.st_size, max_size); if (size > READ_VIRTUAL_BYTES_MAX) return -EFBIG; } n_retries--; } else if (n_retries > 1) { /* Files in /proc are generally smaller than the page size so let's start with * a page size buffer from malloc and only use the max buffer on the final try. */ size = MIN3(page_size() - 1, READ_VIRTUAL_BYTES_MAX, max_size); n_retries = 1; } else { size = MIN(READ_VIRTUAL_BYTES_MAX, max_size); n_retries = 0; } buf = malloc(size + 1); if (!buf) return -ENOMEM; /* Use a bigger allocation if we got it anyway, but not more than the limit. */ size = MIN3(MALLOC_SIZEOF_SAFE(buf) - 1, max_size, READ_VIRTUAL_BYTES_MAX); for (;;) { ssize_t k; /* Read one more byte so we can detect whether the content of the * file has already changed or the guessed size for files from /proc * wasn't large enough . */ k = read(fd, buf, size + 1); if (k >= 0) { n = k; break; } if (errno != EINTR) return -errno; } /* Consider a short read as EOF */ if (n <= size) break; /* If a maximum size is specified and we already read more we know the file is larger, and * can handle this as truncation case. Note that if the size of what we read equals the * maximum size then this doesn't mean truncation, the file might or might not end on that * byte. We need to rerun the loop in that case, with a larger buffer size, so that we read * at least one more byte to be able to distinguish EOF from truncation. */ if (max_size != SIZE_MAX && n > max_size) { n = size; /* Make sure we never use more than what we sized the buffer for (so that * we have one free byte in it for the trailing NUL we add below). */ truncated = true; break; } /* We have no further attempts left? Then the file is apparently larger than our limits. Give up. */ if (n_retries <= 0) return -EFBIG; /* Hmm... either we read too few bytes from /proc or less likely the content of the file * might have been changed (and is now bigger) while we were processing, let's try again * either with the new file size. */ if (lseek(fd, 0, SEEK_SET) < 0) return -errno; buf = mfree(buf); } if (ret_contents) { /* Safety check: if the caller doesn't want to know the size of what we just read it will * rely on the trailing NUL byte. But if there's an embedded NUL byte, then we should refuse * operation as otherwise there'd be ambiguity about what we just read. */ if (!ret_size && memchr(buf, 0, n)) return -EBADMSG; if (n < size) { char *p; /* Return rest of the buffer to libc */ p = realloc(buf, n + 1); if (!p) return -ENOMEM; buf = p; } buf[n] = 0; *ret_contents = TAKE_PTR(buf); } if (ret_size) *ret_size = n; return !truncated; } int read_full_stream_full( FILE *f, const char *filename, uint64_t offset, size_t size, ReadFullFileFlags flags, char **ret_contents, size_t *ret_size) { _cleanup_free_ char *buf = NULL; size_t n, n_next = 0, l, expected_decoded_size = size; int fd, r; assert(f); assert(ret_contents); assert(!FLAGS_SET(flags, READ_FULL_FILE_UNBASE64 | READ_FULL_FILE_UNHEX)); assert(size != SIZE_MAX || !FLAGS_SET(flags, READ_FULL_FILE_FAIL_WHEN_LARGER)); if (offset != UINT64_MAX && offset > LONG_MAX) /* fseek() can only deal with "long" offsets */ return -ERANGE; if ((flags & (READ_FULL_FILE_UNBASE64 | READ_FULL_FILE_UNHEX)) != 0) { if (size <= SIZE_MAX / READ_FULL_FILE_ENCODED_STRING_AMPLIFICATION_BOUNDARY) size *= READ_FULL_FILE_ENCODED_STRING_AMPLIFICATION_BOUNDARY; else size = SIZE_MAX; } fd = fileno(f); if (fd >= 0) { /* If the FILE* object is backed by an fd (as opposed to memory or such, see * fmemopen()), let's optimize our buffering */ struct stat st; if (fstat(fd, &st) < 0) return -errno; if (FLAGS_SET(flags, READ_FULL_FILE_VERIFY_REGULAR)) { r = stat_verify_regular(&st); if (r < 0) return r; } if (S_ISREG(st.st_mode)) { /* Try to start with the right file size if we shall read the file in full. Note * that we increase the size to read here by one, so that the first read attempt * already makes us notice the EOF. If the reported size of the file is zero, we * avoid this logic however, since quite likely it might be a virtual file in procfs * that all report a zero file size. */ if (st.st_size > 0 && (size == SIZE_MAX || FLAGS_SET(flags, READ_FULL_FILE_FAIL_WHEN_LARGER))) { uint64_t rsize = LESS_BY((uint64_t) st.st_size, offset == UINT64_MAX ? 0 : offset); if (rsize < SIZE_MAX) /* overflow check */ n_next = rsize + 1; } if (flags & READ_FULL_FILE_WARN_WORLD_READABLE) (void) warn_file_is_world_accessible(filename, &st, NULL, 0); } } else if (FLAGS_SET(flags, READ_FULL_FILE_VERIFY_REGULAR)) return -EBADFD; /* If we don't know how much to read, figure it out now. If we shall read a part of the file, then * allocate the requested size. If we shall load the full file start with LINE_MAX. Note that if * READ_FULL_FILE_FAIL_WHEN_LARGER we consider the specified size a safety limit, and thus also start * with LINE_MAX, under assumption the file is most likely much shorter. */ if (n_next == 0) n_next = size != SIZE_MAX && !FLAGS_SET(flags, READ_FULL_FILE_FAIL_WHEN_LARGER) ? size : LINE_MAX; /* Never read more than we need to determine that our own limit is hit */ if (n_next > READ_FULL_BYTES_MAX) n_next = READ_FULL_BYTES_MAX + 1; if (offset != UINT64_MAX && fseek(f, offset, SEEK_SET) < 0) return -errno; n = l = 0; for (;;) { char *t; size_t k; /* If we shall fail when reading overly large data, then read exactly one byte more than the * specified size at max, since that'll tell us if there's anymore data beyond the limit. */ if (FLAGS_SET(flags, READ_FULL_FILE_FAIL_WHEN_LARGER) && n_next > size) n_next = size + 1; if (flags & READ_FULL_FILE_SECURE) { t = malloc(n_next + 1); if (!t) { r = -ENOMEM; goto finalize; } memcpy_safe(t, buf, n); explicit_bzero_safe(buf, n); free(buf); } else { t = realloc(buf, n_next + 1); if (!t) return -ENOMEM; } buf = t; /* Unless a size has been explicitly specified, try to read as much as fits into the memory * we allocated (minus 1, to leave one byte for the safety NUL byte) */ n = size == SIZE_MAX ? MALLOC_SIZEOF_SAFE(buf) - 1 : n_next; errno = 0; k = fread(buf + l, 1, n - l, f); assert(k <= n - l); l += k; if (ferror(f)) { r = errno_or_else(EIO); goto finalize; } if (feof(f)) break; if (size != SIZE_MAX && !FLAGS_SET(flags, READ_FULL_FILE_FAIL_WHEN_LARGER)) { /* If we got asked to read some specific size, we already sized the buffer right, hence leave */ assert(l == size); break; } assert(k > 0); /* we can't have read zero bytes because that would have been EOF */ if (FLAGS_SET(flags, READ_FULL_FILE_FAIL_WHEN_LARGER) && l > size) { r = -E2BIG; goto finalize; } if (n >= READ_FULL_BYTES_MAX) { r = -E2BIG; goto finalize; } n_next = MIN(n * 2, READ_FULL_BYTES_MAX); } if (flags & (READ_FULL_FILE_UNBASE64 | READ_FULL_FILE_UNHEX)) { _cleanup_free_ void *decoded = NULL; size_t decoded_size; buf[l++] = 0; if (flags & READ_FULL_FILE_UNBASE64) r = unbase64mem_full(buf, l, flags & READ_FULL_FILE_SECURE, &decoded, &decoded_size); else r = unhexmem_full(buf, l, flags & READ_FULL_FILE_SECURE, &decoded, &decoded_size); if (r < 0) goto finalize; if (flags & READ_FULL_FILE_SECURE) explicit_bzero_safe(buf, n); free_and_replace(buf, decoded); n = l = decoded_size; if (FLAGS_SET(flags, READ_FULL_FILE_FAIL_WHEN_LARGER) && l > expected_decoded_size) { r = -E2BIG; goto finalize; } } if (!ret_size) { /* Safety check: if the caller doesn't want to know the size of what we just read it will rely on the * trailing NUL byte. But if there's an embedded NUL byte, then we should refuse operation as otherwise * there'd be ambiguity about what we just read. */ if (memchr(buf, 0, l)) { r = -EBADMSG; goto finalize; } } buf[l] = 0; *ret_contents = TAKE_PTR(buf); if (ret_size) *ret_size = l; return 0; finalize: if (flags & READ_FULL_FILE_SECURE) explicit_bzero_safe(buf, n); return r; } int read_full_file_full( int dir_fd, const char *filename, uint64_t offset, size_t size, ReadFullFileFlags flags, const char *bind_name, char **ret_contents, size_t *ret_size) { _cleanup_fclose_ FILE *f = NULL; XfopenFlags xflags = XFOPEN_UNLOCKED; int r; assert(ret_contents); if (FLAGS_SET(flags, READ_FULL_FILE_CONNECT_SOCKET) && /* If this is enabled, let's try to connect to it */ offset == UINT64_MAX) /* Seeking is not supported on AF_UNIX sockets */ xflags |= XFOPEN_SOCKET; r = xfopenat_full(dir_fd, filename, "re", 0, xflags, bind_name, &f); if (r < 0) return r; return read_full_stream_full(f, filename, offset, size, flags, ret_contents, ret_size); } int script_get_shebang_interpreter(const char *path, char **ret) { _cleanup_fclose_ FILE *f = NULL; int r; assert(path); f = fopen(path, "re"); if (!f) return -errno; char c; r = safe_fgetc(f, &c); if (r < 0) return r; if (r == 0) return -EBADMSG; if (c != '#') return -EMEDIUMTYPE; r = safe_fgetc(f, &c); if (r < 0) return r; if (r == 0) return -EBADMSG; if (c != '!') return -EMEDIUMTYPE; _cleanup_free_ char *line = NULL; r = read_line(f, LONG_LINE_MAX, &line); if (r < 0) return r; _cleanup_free_ char *p = NULL; const char *s = line; r = extract_first_word(&s, &p, /* separators= */ NULL, /* flags= */ 0); if (r < 0) return r; if (r == 0) return -ENOEXEC; if (ret) *ret = TAKE_PTR(p); return 0; } int get_proc_field(const char *path, const char *key, char **ret) { _cleanup_fclose_ FILE *f = NULL; int r; /* Retrieve one field from a file like /proc/self/status. "key" matches the beginning of the line * and should not include whitespace or the delimiter (':'). * Whitespaces after the ':' will be skipped. Only the first element is returned * (i.e. for /proc/meminfo line "MemTotal: 1024 kB" -> return "1024"). */ assert(path); assert(key); r = fopen_unlocked(path, "re", &f); if (r == -ENOENT && proc_mounted() == 0) return -ENOSYS; if (r < 0) return r; for (;;) { _cleanup_free_ char *line = NULL; r = read_line(f, LONG_LINE_MAX, &line); if (r < 0) return r; if (r == 0) return -ENODATA; char *l = startswith(line, key); if (l && *l == ':') { if (ret) { char *s = strdupcspn(skip_leading_chars(l + 1, " \t"), WHITESPACE); if (!s) return -ENOMEM; *ret = s; } return 0; } } } DIR* xopendirat(int dir_fd, const char *path, int flags) { _cleanup_close_ int fd = -EBADF; assert(dir_fd >= 0 || dir_fd == AT_FDCWD); assert(!(flags & (O_CREAT|O_TMPFILE))); if ((dir_fd == AT_FDCWD || path_is_absolute(path)) && (flags &~ O_DIRECTORY) == 0) return opendir(path); if (isempty(path)) { path = "."; flags |= O_NOFOLLOW; } fd = openat(dir_fd, path, O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|flags); if (fd < 0) return NULL; return take_fdopendir(&fd); } int fopen_mode_to_flags(const char *mode) { const char *p; int flags; assert(mode); if ((p = startswith(mode, "r+"))) flags = O_RDWR; else if ((p = startswith(mode, "r"))) flags = O_RDONLY; else if ((p = startswith(mode, "w+"))) flags = O_RDWR|O_CREAT|O_TRUNC; else if ((p = startswith(mode, "w"))) flags = O_WRONLY|O_CREAT|O_TRUNC; else if ((p = startswith(mode, "a+"))) flags = O_RDWR|O_CREAT|O_APPEND; else if ((p = startswith(mode, "a"))) flags = O_WRONLY|O_CREAT|O_APPEND; else return -EINVAL; for (; *p != 0; p++) { switch (*p) { case 'e': flags |= O_CLOEXEC; break; case 'x': flags |= O_EXCL; break; case 'm': /* ignore this here, fdopen() might care later though */ break; case 'c': /* not sure what to do about this one */ default: return -EINVAL; } } return flags; } static int xfopenat_regular(int dir_fd, const char *path, const char *mode, int open_flags, FILE **ret) { FILE *f; /* A combination of fopen() with openat() */ assert(dir_fd >= 0 || dir_fd == AT_FDCWD); assert(mode); assert(ret); if (dir_fd == AT_FDCWD && path && open_flags == 0) f = fopen(path, mode); else { _cleanup_close_ int fd = -EBADF; int mode_flags; mode_flags = fopen_mode_to_flags(mode); if (mode_flags < 0) return mode_flags; if (path) { fd = openat(dir_fd, path, mode_flags | open_flags); if (fd < 0) return -errno; } else { if (dir_fd == AT_FDCWD) return -EBADF; fd = fd_reopen(dir_fd, (mode_flags | open_flags) & ~O_NOFOLLOW); if (fd < 0) return fd; } f = take_fdopen(&fd, mode); } if (!f) return -errno; *ret = f; return 0; } static int xfopenat_unix_socket(int dir_fd, const char *path, const char *bind_name, FILE **ret) { _cleanup_close_ int sk = -EBADF; FILE *f; int r; assert(dir_fd >= 0 || dir_fd == AT_FDCWD); assert(ret); sk = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0); if (sk < 0) return -errno; if (bind_name) { /* If the caller specified a socket name to bind to, do so before connecting. This is * useful to communicate some minor, short meta-information token from the client to * the server. */ union sockaddr_union bsa; r = sockaddr_un_set_path(&bsa.un, bind_name); if (r < 0) return r; if (bind(sk, &bsa.sa, r) < 0) return -errno; } r = connect_unix_path(sk, dir_fd, path); if (r < 0) return r; if (shutdown(sk, SHUT_WR) < 0) return -errno; f = take_fdopen(&sk, "r"); if (!f) return -errno; *ret = f; return 0; } int xfopenat_full( int dir_fd, const char *path, const char *mode, int open_flags, XfopenFlags flags, const char *bind_name, FILE **ret) { FILE *f = NULL; /* avoid false maybe-uninitialized warning */ int r; assert(dir_fd >= 0 || dir_fd == AT_FDCWD); assert(mode); assert(ret); r = xfopenat_regular(dir_fd, path, mode, open_flags, &f); if (r == -ENXIO && FLAGS_SET(flags, XFOPEN_SOCKET)) { /* ENXIO is what Linux returns if we open a node that is an AF_UNIX socket */ r = xfopenat_unix_socket(dir_fd, path, bind_name, &f); if (IN_SET(r, -ENOTSOCK, -EINVAL)) return -ENXIO; /* propagate original error if this is not a socket after all */ } if (r < 0) return r; if (FLAGS_SET(flags, XFOPEN_UNLOCKED)) (void) __fsetlocking(f, FSETLOCKING_BYCALLER); *ret = f; return 0; } int fdopen_independent(int fd, const char *mode, FILE **ret) { _cleanup_close_ int copy_fd = -EBADF; _cleanup_fclose_ FILE *f = NULL; int mode_flags; assert(fd >= 0); assert(mode); assert(ret); /* A combination of fdopen() + fd_reopen(). i.e. reopens the inode the specified fd points to and * returns a FILE* for it */ mode_flags = fopen_mode_to_flags(mode); if (mode_flags < 0) return mode_flags; /* Flags returned by fopen_mode_to_flags might contain O_CREAT, but it doesn't make sense for fd_reopen * since we're working on an existing fd anyway. Let's drop it here to avoid triggering assertion. */ copy_fd = fd_reopen(fd, mode_flags & ~O_CREAT); if (copy_fd < 0) return copy_fd; f = take_fdopen(©_fd, mode); if (!f) return -errno; *ret = TAKE_PTR(f); return 0; } static int search_and_open_internal( const char *path, int mode, /* if ret_fd is NULL this is an [FRWX]_OK mode for access(), otherwise an open mode for open() */ const char *root, char **search, int *ret_fd, char **ret_path) { int r; assert(!ret_fd || !FLAGS_SET(mode, O_CREAT)); /* We don't support O_CREAT for this */ assert(path); if (path_is_absolute(path)) { _cleanup_close_ int fd = -EBADF; if (ret_fd) /* We only specify 0777 here to appease static analyzers, it's never used since we * don't support O_CREAT here */ r = fd = RET_NERRNO(open(path, mode, 0777)); else r = RET_NERRNO(access(path, mode)); if (r < 0) return r; if (ret_path) { r = path_simplify_alloc(path, ret_path); if (r < 0) return r; } if (ret_fd) *ret_fd = TAKE_FD(fd); return 0; } if (!path_strv_resolve_uniq(search, root)) return -ENOMEM; STRV_FOREACH(i, search) { _cleanup_close_ int fd = -EBADF; _cleanup_free_ char *p = NULL; p = path_join(root, *i, path); if (!p) return -ENOMEM; if (ret_fd) /* as above, 0777 is static analyzer appeasement */ r = fd = RET_NERRNO(open(p, mode, 0777)); else r = RET_NERRNO(access(p, F_OK)); if (r >= 0) { if (ret_path) *ret_path = path_simplify(TAKE_PTR(p)); if (ret_fd) *ret_fd = TAKE_FD(fd); return 0; } if (r != -ENOENT) return r; } return -ENOENT; } int search_and_open( const char *path, int mode, const char *root, char **search, int *ret_fd, char **ret_path) { _cleanup_strv_free_ char **copy = NULL; assert(path); copy = strv_copy(search); if (!copy) return -ENOMEM; return search_and_open_internal(path, mode, root, copy, ret_fd, ret_path); } static int search_and_fopen_internal( const char *path, const char *mode, const char *root, char **search, FILE **ret_file, char **ret_path) { _cleanup_free_ char *found_path = NULL; _cleanup_close_ int fd = -EBADF; int r; assert(path); assert(mode || !ret_file); r = search_and_open( path, mode ? fopen_mode_to_flags(mode) : 0, root, search, ret_file ? &fd : NULL, ret_path ? &found_path : NULL); if (r < 0) return r; if (ret_file) { FILE *f = take_fdopen(&fd, mode); if (!f) return -errno; *ret_file = f; } if (ret_path) *ret_path = TAKE_PTR(found_path); return 0; } int search_and_fopen( const char *path, const char *mode, const char *root, const char **search, FILE **ret_file, char **ret_path) { _cleanup_strv_free_ char **copy = NULL; assert(path); assert(mode || !ret_file); copy = strv_copy((char**) search); if (!copy) return -ENOMEM; return search_and_fopen_internal(path, mode, root, copy, ret_file, ret_path); } int search_and_fopen_nulstr( const char *path, const char *mode, const char *root, const char *search, FILE **ret_file, char **ret_path) { _cleanup_strv_free_ char **l = NULL; assert(path); assert(mode || !ret_file); l = strv_split_nulstr(search); if (!l) return -ENOMEM; return search_and_fopen_internal(path, mode, root, l, ret_file, ret_path); } int fflush_and_check(FILE *f) { assert(f); errno = 0; fflush(f); if (ferror(f)) return errno_or_else(EIO); return 0; } int fflush_sync_and_check(FILE *f) { int r, fd; assert(f); r = fflush_and_check(f); if (r < 0) return r; /* Not all file streams have an fd associated (think: fmemopen()), let's handle this gracefully and * assume that in that case we need no explicit syncing */ fd = fileno(f); if (fd < 0) return 0; r = fsync_full(fd); if (r < 0) return r; return 0; } int write_timestamp_file_atomic(const char *fn, usec_t n) { char ln[DECIMAL_STR_MAX(n)+2]; /* Creates a "timestamp" file, that contains nothing but a * usec_t timestamp, formatted in ASCII. */ if (!timestamp_is_set(n)) return -ERANGE; xsprintf(ln, USEC_FMT "\n", n); return write_string_file(fn, ln, WRITE_STRING_FILE_CREATE|WRITE_STRING_FILE_ATOMIC); } int read_timestamp_file(const char *fn, usec_t *ret) { _cleanup_free_ char *ln = NULL; uint64_t t; int r; r = read_one_line_file(fn, &ln); if (r < 0) return r; r = safe_atou64(ln, &t); if (r < 0) return r; if (!timestamp_is_set(t)) return -ERANGE; *ret = (usec_t) t; return 0; } int fputs_with_separator(FILE *f, const char *s, const char *separator, bool *space) { assert(s); assert(space); /* Outputs the specified string with fputs(), but optionally prefixes it with a separator. * The *space parameter when specified shall initially point to a boolean variable initialized * to false. It is set to true after the first invocation. This call is supposed to be use in loops, * where a separator shall be inserted between each element, but not before the first one. */ if (!f) f = stdout; if (!separator) separator = " "; if (*space) if (fputs(separator, f) < 0) return -EIO; *space = true; if (fputs(s, f) < 0) return -EIO; return 0; } int fputs_with_newline(FILE *f, const char *s) { /* This is like fputs() but outputs a trailing newline char, but only if the string isn't empty * and doesn't end in a newline already. Returns 0 in case we didn't append a newline, > 0 otherwise. */ if (isempty(s)) return 0; if (!f) f = stdout; if (fputs(s, f) < 0) return -EIO; if (endswith(s, "\n")) return 0; if (fputc('\n', f) < 0) return -EIO; return 1; } /* A bitmask of the EOL markers we know */ typedef enum EndOfLineMarker { EOL_NONE = 0, EOL_ZERO = 1 << 0, /* \0 (aka NUL) */ EOL_TEN = 1 << 1, /* \n (aka NL, aka LF) */ EOL_THIRTEEN = 1 << 2, /* \r (aka CR) */ } EndOfLineMarker; static EndOfLineMarker categorize_eol(char c, ReadLineFlags flags) { if (!FLAGS_SET(flags, READ_LINE_ONLY_NUL)) { if (c == '\n') return EOL_TEN; if (c == '\r') return EOL_THIRTEEN; } if (c == '\0') return EOL_ZERO; return EOL_NONE; } DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(FILE*, funlockfile, NULL); int read_line_full(FILE *f, size_t limit, ReadLineFlags flags, char **ret) { _cleanup_free_ char *buffer = NULL; size_t n = 0, count = 0; int r; assert(f); /* Something like a bounded version of getline(). * * Considers EOF, \n, \r and \0 end of line delimiters (or combinations of these), and does not include these * delimiters in the string returned. Specifically, recognizes the following combinations of markers as line * endings: * * • \n (UNIX) * • \r (old MacOS) * • \0 (C strings) * • \n\0 * • \r\0 * • \r\n (Windows) * • \n\r * • \r\n\0 * • \n\r\0 * * Returns the number of bytes read from the files (i.e. including delimiters — this hence usually differs from * the number of characters in the returned string). When EOF is hit, 0 is returned. * * The input parameter limit is the maximum numbers of characters in the returned string, i.e. excluding * delimiters. If the limit is hit we fail and return -ENOBUFS. * * If a line shall be skipped ret may be initialized as NULL. */ if (ret) { if (!GREEDY_REALLOC(buffer, 1)) return -ENOMEM; } { _unused_ _cleanup_(funlockfilep) FILE *flocked = f; EndOfLineMarker previous_eol = EOL_NONE; flockfile(f); for (;;) { EndOfLineMarker eol; char c; if (n >= limit) return -ENOBUFS; if (count >= INT_MAX) /* We couldn't return the counter anymore as "int", hence refuse this */ return -ENOBUFS; r = safe_fgetc(f, &c); if (r < 0) return r; if (r == 0) /* EOF is definitely EOL */ break; eol = categorize_eol(c, flags); if (FLAGS_SET(previous_eol, EOL_ZERO) || (eol == EOL_NONE && previous_eol != EOL_NONE) || (eol != EOL_NONE && (previous_eol & eol) != 0)) { /* Previous char was a NUL? This is not an EOL, but the previous char was? This type of * EOL marker has been seen right before? In either of these three cases we are * done. But first, let's put this character back in the queue. (Note that we have to * cast this to (unsigned char) here as ungetc() expects a positive 'int', and if we * are on an architecture where 'char' equals 'signed char' we need to ensure we don't * pass a negative value here. That said, to complicate things further ungetc() is * actually happy with most negative characters and implicitly casts them back to * positive ones as needed, except for \xff (aka -1, aka EOF), which it refuses. What a * godawful API!) */ assert_se(ungetc((unsigned char) c, f) != EOF); break; } count++; if (eol != EOL_NONE) { /* If we are on a tty, we can't shouldn't wait for more input, because that * generally means waiting for the user, interactively. In the case of a TTY * we expect only \n as the single EOL marker, so we are in the lucky * position that there is no need to wait. We check this condition last, to * avoid isatty() check if not necessary. */ if ((flags & (READ_LINE_IS_A_TTY|READ_LINE_NOT_A_TTY)) == 0) { int fd; fd = fileno(f); if (fd < 0) /* Maybe an fmemopen() stream? Handle this gracefully, * and don't call isatty() on an invalid fd */ flags |= READ_LINE_NOT_A_TTY; else flags |= isatty_safe(fd) ? READ_LINE_IS_A_TTY : READ_LINE_NOT_A_TTY; } if (FLAGS_SET(flags, READ_LINE_IS_A_TTY)) break; } if (eol != EOL_NONE) { previous_eol |= eol; continue; } if (ret) { if (!GREEDY_REALLOC(buffer, n + 2)) return -ENOMEM; buffer[n] = c; } n++; } } if (ret) { buffer[n] = 0; *ret = TAKE_PTR(buffer); } return (int) count; } int read_stripped_line(FILE *f, size_t limit, char **ret) { _cleanup_free_ char *s = NULL; int r, k; assert(f); r = read_line(f, limit, ret ? &s : NULL); if (r < 0) return r; if (ret) { const char *p = strstrip(s); if (p == s) *ret = TAKE_PTR(s); else { k = strdup_to(ret, p); if (k < 0) return k; } } return r > 0; /* Return 1 if something was read. */ } int safe_fgetc(FILE *f, char *ret) { int k; assert(f); /* A safer version of plain fgetc(): let's propagate the error that happened while reading as such, and * separate the EOF condition from the byte read, to avoid those confusion signed/unsigned issues fgetc() * has. */ errno = 0; k = fgetc(f); if (k == EOF) { if (ferror(f)) return errno_or_else(EIO); if (ret) *ret = 0; return 0; } if (ret) *ret = k; return 1; } int warn_file_is_world_accessible(const char *filename, struct stat *st, const char *unit, unsigned line) { struct stat _st; if (!filename) return 0; if (!st) { if (stat(filename, &_st) < 0) return -errno; st = &_st; } if ((st->st_mode & S_IRWXO) == 0) return 0; if (unit) log_syntax(unit, LOG_WARNING, filename, line, 0, "%s has %04o mode that is too permissive, please adjust the ownership and access mode.", filename, st->st_mode & 07777); else log_warning("%s has %04o mode that is too permissive, please adjust the ownership and access mode.", filename, st->st_mode & 07777); return 0; }