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-rw-r--r--src/basic/stat-util.c520
1 files changed, 520 insertions, 0 deletions
diff --git a/src/basic/stat-util.c b/src/basic/stat-util.c
new file mode 100644
index 0000000..c54374b
--- /dev/null
+++ b/src/basic/stat-util.c
@@ -0,0 +1,520 @@
+/* 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.h"
+#include "dirent-util.h"
+#include "errno-util.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "filesystems.h"
+#include "fs-util.h"
+#include "hash-funcs.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 = -EBADF;
+ 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_and_stat(fn, root, CHASE_PREFIX_ROOT, NULL, &st);
+ if (r < 0)
+ return r;
+
+ return null_or_empty(&st);
+}
+
+static int fd_is_read_only_fs(int fd) {
+ struct statvfs st;
+
+ assert(fd >= 0);
+
+ if (fstatvfs(fd, &st) < 0)
+ return -errno;
+
+ if (st.f_flag & ST_RDONLY)
+ return true;
+
+ /* On NFS, fstatvfs() 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_fd(fd, W_OK) == -EROFS)
+ return true;
+
+ return false;
+}
+
+int path_is_read_only_fs(const char *path) {
+ _cleanup_close_ int fd = -EBADF;
+
+ assert(path);
+
+ fd = open(path, O_CLOEXEC | O_PATH);
+ if (fd < 0)
+ return -errno;
+
+ return fd_is_read_only_fs(fd);
+}
+
+int inode_same_at(int fda, const char *filea, int fdb, const char *fileb, int flags) {
+ struct stat a, b;
+
+ assert(fda >= 0 || fda == AT_FDCWD);
+ assert(filea);
+ assert(fdb >= 0 || fdb == AT_FDCWD);
+ assert(fileb);
+
+ if (fstatat(fda, filea, &a, flags) < 0)
+ return log_debug_errno(errno, "Cannot stat %s: %m", filea);
+
+ if (fstatat(fdb, 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 is_fs_type_at(int dir_fd, const char *path, statfs_f_type_t magic_value) {
+ struct statfs s;
+ int r;
+
+ r = xstatfsat(dir_fd, path, &s);
+ if (r < 0)
+ return r;
+
+ 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 verify_regular_at(int dir_fd, const char *path, bool follow) {
+ struct stat st;
+
+ assert(dir_fd >= 0 || dir_fd == AT_FDCWD);
+ assert(path);
+
+ if (fstatat(dir_fd, path, &st, (isempty(path) ? AT_EMPTY_PATH : 0) | (follow ? 0 : AT_SYMLINK_NOFOLLOW)) < 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;
+}
+
+static bool is_statx_fatal_error(int err, int flags) {
+ assert(err < 0);
+
+ /* If statx() is not supported or if we see EPERM (which might indicate seccomp filtering or so),
+ * let's do a fallback. Note that on EACCES we'll not fall back, since that is likely an indication of
+ * fs access issues, which we should propagate. */
+ if (ERRNO_IS_NOT_SUPPORTED(err) || err == -EPERM)
+ return false;
+
+ /* When unsupported flags are specified, glibc's fallback function returns -EINVAL.
+ * See statx_generic() in glibc. */
+ if (err != -EINVAL)
+ return true;
+
+ if ((flags & ~(AT_EMPTY_PATH | AT_NO_AUTOMOUNT | AT_SYMLINK_NOFOLLOW | AT_STATX_SYNC_AS_STAT)) != 0)
+ return false; /* Unsupported flags are specified. Let's try to use our implementation. */
+
+ return true;
+}
+
+int statx_fallback(int dfd, const char *path, int flags, unsigned mask, struct statx *sx) {
+ static bool avoid_statx = false;
+ struct stat st;
+ int r;
+
+ if (!avoid_statx) {
+ r = RET_NERRNO(statx(dfd, path, flags, mask, sx));
+ if (r >= 0 || is_statx_fatal_error(r, flags))
+ return r;
+
+ 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;
+}
+
+int xstatfsat(int dir_fd, const char *path, struct statfs *ret) {
+ _cleanup_close_ int fd = -EBADF;
+
+ assert(dir_fd >= 0 || dir_fd == AT_FDCWD);
+ assert(ret);
+
+ fd = xopenat(dir_fd, path, O_PATH|O_CLOEXEC|O_NOCTTY, /* xopen_flags = */ 0, /* mode = */ 0);
+ if (fd < 0)
+ return fd;
+
+ return RET_NERRNO(fstatfs(fd, ret));
+}
+
+void inode_hash_func(const struct stat *q, struct siphash *state) {
+ siphash24_compress(&q->st_dev, sizeof(q->st_dev), state);
+ siphash24_compress(&q->st_ino, sizeof(q->st_ino), state);
+}
+
+int inode_compare_func(const struct stat *a, const struct stat *b) {
+ int r;
+
+ r = CMP(a->st_dev, b->st_dev);
+ if (r != 0)
+ return r;
+
+ return CMP(a->st_ino, b->st_ino);
+}
+
+DEFINE_HASH_OPS_WITH_KEY_DESTRUCTOR(inode_hash_ops, struct stat, inode_hash_func, inode_compare_func, free);
+
+const char* inode_type_to_string(mode_t m) {
+
+ /* Returns a short string for the inode type. We use the same name as the underlying macros for each
+ * inode type. */
+
+ switch (m & S_IFMT) {
+ case S_IFREG:
+ return "reg";
+ case S_IFDIR:
+ return "dir";
+ case S_IFLNK:
+ return "lnk";
+ case S_IFCHR:
+ return "chr";
+ case S_IFBLK:
+ return "blk";
+ case S_IFIFO:
+ return "fifo";
+ case S_IFSOCK:
+ return "sock";
+ }
+
+ return NULL;
+}
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