diff options
Diffstat (limited to 'src/basic/stat-util.c')
| -rw-r--r-- | src/basic/stat-util.c | 443 |
1 files changed, 443 insertions, 0 deletions
diff --git a/src/basic/stat-util.c b/src/basic/stat-util.c new file mode 100644 index 0000000..468840d --- /dev/null +++ b/src/basic/stat-util.c @@ -0,0 +1,443 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include <errno.h> +#include <fcntl.h> +#include <sched.h> +#include <sys/statvfs.h> +#include <sys/types.h> +#include <unistd.h> + +#include "alloc-util.h" +#include "chase-symlinks.h" +#include "dirent-util.h" +#include "errno-util.h" +#include "fd-util.h" +#include "fileio.h" +#include "filesystems.h" +#include "fs-util.h" +#include "macro.h" +#include "missing_fs.h" +#include "missing_magic.h" +#include "missing_syscall.h" +#include "nulstr-util.h" +#include "parse-util.h" +#include "stat-util.h" +#include "string-util.h" + +int is_symlink(const char *path) { + struct stat info; + + assert(path); + + if (lstat(path, &info) < 0) + return -errno; + + return !!S_ISLNK(info.st_mode); +} + +int is_dir_full(int atfd, const char* path, bool follow) { + struct stat st; + int r; + + assert(atfd >= 0 || atfd == AT_FDCWD); + assert(atfd >= 0 || path); + + if (path) + r = fstatat(atfd, path, &st, follow ? 0 : AT_SYMLINK_NOFOLLOW); + else + r = fstat(atfd, &st); + if (r < 0) + return -errno; + + return !!S_ISDIR(st.st_mode); +} + +int is_device_node(const char *path) { + struct stat info; + + assert(path); + + if (lstat(path, &info) < 0) + return -errno; + + return !!(S_ISBLK(info.st_mode) || S_ISCHR(info.st_mode)); +} + +int dir_is_empty_at(int dir_fd, const char *path, bool ignore_hidden_or_backup) { + _cleanup_close_ int fd = -1; + struct dirent *buf; + size_t m; + + if (path) { + assert(dir_fd >= 0 || dir_fd == AT_FDCWD); + + fd = openat(dir_fd, path, O_RDONLY|O_DIRECTORY|O_CLOEXEC); + if (fd < 0) + return -errno; + } else if (dir_fd == AT_FDCWD) { + fd = open(".", O_RDONLY|O_DIRECTORY|O_CLOEXEC); + if (fd < 0) + return -errno; + } else { + /* Note that DUPing is not enough, as the internal pointer would still be shared and moved + * getedents64(). */ + assert(dir_fd >= 0); + + fd = fd_reopen(dir_fd, O_RDONLY|O_DIRECTORY|O_CLOEXEC); + if (fd < 0) + return fd; + } + + /* Allocate space for at least 3 full dirents, since every dir has at least two entries ("." + + * ".."), and only once we have seen if there's a third we know whether the dir is empty or not. If + * 'ignore_hidden_or_backup' is true we'll allocate a bit more, since we might skip over a bunch of + * entries that we end up ignoring. */ + m = (ignore_hidden_or_backup ? 16 : 3) * DIRENT_SIZE_MAX; + buf = alloca(m); + + for (;;) { + struct dirent *de; + ssize_t n; + + n = getdents64(fd, buf, m); + if (n < 0) + return -errno; + if (n == 0) + break; + + assert((size_t) n <= m); + msan_unpoison(buf, n); + + FOREACH_DIRENT_IN_BUFFER(de, buf, n) + if (!(ignore_hidden_or_backup ? hidden_or_backup_file(de->d_name) : dot_or_dot_dot(de->d_name))) + return 0; + } + + return 1; +} + +bool null_or_empty(struct stat *st) { + assert(st); + + if (S_ISREG(st->st_mode) && st->st_size <= 0) + return true; + + /* We don't want to hardcode the major/minor of /dev/null, hence we do a simpler "is this a character + * device node?" check. */ + + if (S_ISCHR(st->st_mode)) + return true; + + return false; +} + +int null_or_empty_path_with_root(const char *fn, const char *root) { + struct stat st; + int r; + + assert(fn); + + /* A symlink to /dev/null or an empty file? + * When looking under root_dir, we can't expect /dev/ to be mounted, + * so let's see if the path is a (possibly dangling) symlink to /dev/null. */ + + if (path_equal_ptr(path_startswith(fn, root ?: "/"), "dev/null")) + return true; + + r = chase_symlinks_and_stat(fn, root, CHASE_PREFIX_ROOT, NULL, &st, NULL); + if (r < 0) + return r; + + return null_or_empty(&st); +} + +int null_or_empty_fd(int fd) { + struct stat st; + + assert(fd >= 0); + + if (fstat(fd, &st) < 0) + return -errno; + + return null_or_empty(&st); +} + +int path_is_read_only_fs(const char *path) { + struct statvfs st; + + assert(path); + + if (statvfs(path, &st) < 0) + return -errno; + + if (st.f_flag & ST_RDONLY) + return true; + + /* On NFS, statvfs() might not reflect whether we can actually + * write to the remote share. Let's try again with + * access(W_OK) which is more reliable, at least sometimes. */ + if (access(path, W_OK) < 0 && errno == EROFS) + return true; + + return false; +} + +int files_same(const char *filea, const char *fileb, int flags) { + struct stat a, b; + + assert(filea); + assert(fileb); + + if (fstatat(AT_FDCWD, filea, &a, flags) < 0) + return log_debug_errno(errno, "Cannot stat %s: %m", filea); + + if (fstatat(AT_FDCWD, fileb, &b, flags) < 0) + return log_debug_errno(errno, "Cannot stat %s: %m", fileb); + + return stat_inode_same(&a, &b); +} + +bool is_fs_type(const struct statfs *s, statfs_f_type_t magic_value) { + assert(s); + assert_cc(sizeof(statfs_f_type_t) >= sizeof(s->f_type)); + + return F_TYPE_EQUAL(s->f_type, magic_value); +} + +int fd_is_fs_type(int fd, statfs_f_type_t magic_value) { + struct statfs s; + + if (fstatfs(fd, &s) < 0) + return -errno; + + return is_fs_type(&s, magic_value); +} + +int path_is_fs_type(const char *path, statfs_f_type_t magic_value) { + struct statfs s; + + if (statfs(path, &s) < 0) + return -errno; + + return is_fs_type(&s, magic_value); +} + +bool is_temporary_fs(const struct statfs *s) { + return fs_in_group(s, FILESYSTEM_SET_TEMPORARY); +} + +bool is_network_fs(const struct statfs *s) { + return fs_in_group(s, FILESYSTEM_SET_NETWORK); +} + +int fd_is_temporary_fs(int fd) { + struct statfs s; + + if (fstatfs(fd, &s) < 0) + return -errno; + + return is_temporary_fs(&s); +} + +int fd_is_network_fs(int fd) { + struct statfs s; + + if (fstatfs(fd, &s) < 0) + return -errno; + + return is_network_fs(&s); +} + +int path_is_temporary_fs(const char *path) { + struct statfs s; + + if (statfs(path, &s) < 0) + return -errno; + + return is_temporary_fs(&s); +} + +int path_is_network_fs(const char *path) { + struct statfs s; + + if (statfs(path, &s) < 0) + return -errno; + + return is_network_fs(&s); +} + +int stat_verify_regular(const struct stat *st) { + assert(st); + + /* Checks whether the specified stat() structure refers to a regular file. If not returns an appropriate error + * code. */ + + if (S_ISDIR(st->st_mode)) + return -EISDIR; + + if (S_ISLNK(st->st_mode)) + return -ELOOP; + + if (!S_ISREG(st->st_mode)) + return -EBADFD; + + return 0; +} + +int fd_verify_regular(int fd) { + struct stat st; + + assert(fd >= 0); + + if (fstat(fd, &st) < 0) + return -errno; + + return stat_verify_regular(&st); +} + +int stat_verify_directory(const struct stat *st) { + assert(st); + + if (S_ISLNK(st->st_mode)) + return -ELOOP; + + if (!S_ISDIR(st->st_mode)) + return -ENOTDIR; + + return 0; +} + +int fd_verify_directory(int fd) { + struct stat st; + + assert(fd >= 0); + + if (fstat(fd, &st) < 0) + return -errno; + + return stat_verify_directory(&st); +} + +int proc_mounted(void) { + int r; + + /* A quick check of procfs is properly mounted */ + + r = path_is_fs_type("/proc/", PROC_SUPER_MAGIC); + if (r == -ENOENT) /* not mounted at all */ + return false; + + return r; +} + +bool stat_inode_same(const struct stat *a, const struct stat *b) { + + /* Returns if the specified stat structure references the same (though possibly modified) inode. Does + * a thorough check, comparing inode nr, backing device and if the inode is still of the same type. */ + + return a && b && + (a->st_mode & S_IFMT) != 0 && /* We use the check for .st_mode if the structure was ever initialized */ + ((a->st_mode ^ b->st_mode) & S_IFMT) == 0 && /* same inode type */ + a->st_dev == b->st_dev && + a->st_ino == b->st_ino; +} + +bool stat_inode_unmodified(const struct stat *a, const struct stat *b) { + + /* Returns if the specified stat structures reference the same, unmodified inode. This check tries to + * be reasonably careful when detecting changes: we check both inode and mtime, to cater for file + * systems where mtimes are fixed to 0 (think: ostree/nixos type installations). We also check file + * size, backing device, inode type and if this refers to a device not the major/minor. + * + * Note that we don't care if file attributes such as ownership or access mode change, this here is + * about contents of the file. The purpose here is to detect file contents changes, and nothing + * else. */ + + return stat_inode_same(a, b) && + a->st_mtim.tv_sec == b->st_mtim.tv_sec && + a->st_mtim.tv_nsec == b->st_mtim.tv_nsec && + (!S_ISREG(a->st_mode) || a->st_size == b->st_size) && /* if regular file, compare file size */ + (!(S_ISCHR(a->st_mode) || S_ISBLK(a->st_mode)) || a->st_rdev == b->st_rdev); /* if device node, also compare major/minor, because we can */ +} + +bool statx_inode_same(const struct statx *a, const struct statx *b) { + + /* Same as stat_inode_same() but for struct statx */ + + return a && b && + FLAGS_SET(a->stx_mask, STATX_TYPE|STATX_INO) && FLAGS_SET(b->stx_mask, STATX_TYPE|STATX_INO) && + (a->stx_mode & S_IFMT) != 0 && + ((a->stx_mode ^ b->stx_mode) & S_IFMT) == 0 && + a->stx_dev_major == b->stx_dev_major && + a->stx_dev_minor == b->stx_dev_minor && + a->stx_ino == b->stx_ino; +} + +bool statx_mount_same(const struct new_statx *a, const struct new_statx *b) { + if (!a || !b) + return false; + + /* if we have the mount ID, that's all we need */ + if (FLAGS_SET(a->stx_mask, STATX_MNT_ID) && FLAGS_SET(b->stx_mask, STATX_MNT_ID)) + return a->stx_mnt_id == b->stx_mnt_id; + + /* Otherwise, major/minor of backing device must match */ + return a->stx_dev_major == b->stx_dev_major && + a->stx_dev_minor == b->stx_dev_minor; +} + +int statx_fallback(int dfd, const char *path, int flags, unsigned mask, struct statx *sx) { + static bool avoid_statx = false; + struct stat st; + + if (!avoid_statx) { + if (statx(dfd, path, flags, mask, sx) < 0) { + if (!ERRNO_IS_NOT_SUPPORTED(errno) && errno != EPERM) + return -errno; + + /* If statx() is not supported or if we see EPERM (which might indicate seccomp + * filtering or so), let's do a fallback. Not that on EACCES we'll not fall back, + * since that is likely an indication of fs access issues, which we should + * propagate */ + } else + return 0; + + avoid_statx = true; + } + + /* Only do fallback if fstatat() supports the flag too, or if it's one of the sync flags, which are + * OK to ignore */ + if ((flags & ~(AT_EMPTY_PATH|AT_NO_AUTOMOUNT|AT_SYMLINK_NOFOLLOW| + AT_STATX_SYNC_AS_STAT|AT_STATX_FORCE_SYNC|AT_STATX_DONT_SYNC)) != 0) + return -EOPNOTSUPP; + + if (fstatat(dfd, path, &st, flags & (AT_EMPTY_PATH|AT_NO_AUTOMOUNT|AT_SYMLINK_NOFOLLOW)) < 0) + return -errno; + + *sx = (struct statx) { + .stx_mask = STATX_TYPE|STATX_MODE| + STATX_NLINK|STATX_UID|STATX_GID| + STATX_ATIME|STATX_MTIME|STATX_CTIME| + STATX_INO|STATX_SIZE|STATX_BLOCKS, + .stx_blksize = st.st_blksize, + .stx_nlink = st.st_nlink, + .stx_uid = st.st_uid, + .stx_gid = st.st_gid, + .stx_mode = st.st_mode, + .stx_ino = st.st_ino, + .stx_size = st.st_size, + .stx_blocks = st.st_blocks, + .stx_rdev_major = major(st.st_rdev), + .stx_rdev_minor = minor(st.st_rdev), + .stx_dev_major = major(st.st_dev), + .stx_dev_minor = minor(st.st_dev), + .stx_atime.tv_sec = st.st_atim.tv_sec, + .stx_atime.tv_nsec = st.st_atim.tv_nsec, + .stx_mtime.tv_sec = st.st_mtim.tv_sec, + .stx_mtime.tv_nsec = st.st_mtim.tv_nsec, + .stx_ctime.tv_sec = st.st_ctim.tv_sec, + .stx_ctime.tv_nsec = st.st_ctim.tv_nsec, + }; + + return 0; +} |