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-rw-r--r--src/basic/stat-util.c472
1 files changed, 472 insertions, 0 deletions
diff --git a/src/basic/stat-util.c b/src/basic/stat-util.c
new file mode 100644
index 0000000..f999681
--- /dev/null
+++ b/src/basic/stat-util.c
@@ -0,0 +1,472 @@
+/* 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 "dirent-util.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "fs-util.h"
+#include "macro.h"
+#include "missing_fs.h"
+#include "missing_magic.h"
+#include "missing_syscall.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(const char* path, bool follow) {
+ struct stat st;
+ int r;
+
+ assert(path);
+
+ if (follow)
+ r = stat(path, &st);
+ else
+ r = lstat(path, &st);
+ if (r < 0)
+ return -errno;
+
+ return !!S_ISDIR(st.st_mode);
+}
+
+int is_dir_fd(int fd) {
+ struct stat st;
+
+ if (fstat(fd, &st) < 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) {
+ _cleanup_close_ int fd = -1;
+ _cleanup_closedir_ DIR *d = NULL;
+ struct dirent *de;
+
+ if (path)
+ fd = openat(dir_fd, path, O_RDONLY|O_DIRECTORY|O_CLOEXEC);
+ else
+ fd = fcntl(fd, F_DUPFD_CLOEXEC, 3);
+ if (fd < 0)
+ return -errno;
+
+ d = take_fdopendir(&fd);
+ if (!d)
+ return -errno;
+
+ FOREACH_DIRENT(de, d, return -errno)
+ 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(const char *fn) {
+ struct stat st;
+
+ assert(fn);
+
+ /* If we have the path, let's do an easy text comparison first. */
+ if (path_equal(fn, "/dev/null"))
+ return true;
+
+ if (stat(fn, &st) < 0)
+ return -errno;
+
+ 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 -errno;
+
+ if (fstatat(AT_FDCWD, fileb, &b, flags) < 0)
+ return -errno;
+
+ return a.st_dev == b.st_dev &&
+ a.st_ino == b.st_ino;
+}
+
+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 is_fs_type(s, TMPFS_MAGIC) ||
+ is_fs_type(s, RAMFS_MAGIC);
+}
+
+bool is_network_fs(const struct statfs *s) {
+ return is_fs_type(s, CIFS_MAGIC_NUMBER) ||
+ is_fs_type(s, CODA_SUPER_MAGIC) ||
+ is_fs_type(s, NCP_SUPER_MAGIC) ||
+ is_fs_type(s, NFS_SUPER_MAGIC) ||
+ is_fs_type(s, SMB_SUPER_MAGIC) ||
+ is_fs_type(s, V9FS_MAGIC) ||
+ is_fs_type(s, AFS_SUPER_MAGIC) ||
+ is_fs_type(s, OCFS2_SUPER_MAGIC);
+}
+
+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 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 device_path_make_major_minor(mode_t mode, dev_t devno, char **ret) {
+ const char *t;
+
+ /* Generates the /dev/{char|block}/MAJOR:MINOR path for a dev_t */
+
+ if (S_ISCHR(mode))
+ t = "char";
+ else if (S_ISBLK(mode))
+ t = "block";
+ else
+ return -ENODEV;
+
+ if (asprintf(ret, "/dev/%s/%u:%u", t, major(devno), minor(devno)) < 0)
+ return -ENOMEM;
+
+ return 0;
+}
+
+int device_path_make_canonical(mode_t mode, dev_t devno, char **ret) {
+ _cleanup_free_ char *p = NULL;
+ int r;
+
+ /* Finds the canonical path for a device, i.e. resolves the /dev/{char|block}/MAJOR:MINOR path to the end. */
+
+ assert(ret);
+
+ if (major(devno) == 0 && minor(devno) == 0) {
+ char *s;
+
+ /* A special hack to make sure our 'inaccessible' device nodes work. They won't have symlinks in
+ * /dev/block/ and /dev/char/, hence we handle them specially here. */
+
+ if (S_ISCHR(mode))
+ s = strdup("/run/systemd/inaccessible/chr");
+ else if (S_ISBLK(mode))
+ s = strdup("/run/systemd/inaccessible/blk");
+ else
+ return -ENODEV;
+
+ if (!s)
+ return -ENOMEM;
+
+ *ret = s;
+ return 0;
+ }
+
+ r = device_path_make_major_minor(mode, devno, &p);
+ if (r < 0)
+ return r;
+
+ return chase_symlinks(p, NULL, 0, ret, NULL);
+}
+
+int device_path_parse_major_minor(const char *path, mode_t *ret_mode, dev_t *ret_devno) {
+ mode_t mode;
+ dev_t devno;
+ int r;
+
+ /* Tries to extract the major/minor directly from the device path if we can. Handles /dev/block/ and /dev/char/
+ * paths, as well out synthetic inaccessible device nodes. Never goes to disk. Returns -ENODEV if the device
+ * path cannot be parsed like this. */
+
+ if (path_equal(path, "/run/systemd/inaccessible/chr")) {
+ mode = S_IFCHR;
+ devno = makedev(0, 0);
+ } else if (path_equal(path, "/run/systemd/inaccessible/blk")) {
+ mode = S_IFBLK;
+ devno = makedev(0, 0);
+ } else {
+ const char *w;
+
+ w = path_startswith(path, "/dev/block/");
+ if (w)
+ mode = S_IFBLK;
+ else {
+ w = path_startswith(path, "/dev/char/");
+ if (!w)
+ return -ENODEV;
+
+ mode = S_IFCHR;
+ }
+
+ r = parse_dev(w, &devno);
+ if (r < 0)
+ return r;
+ }
+
+ if (ret_mode)
+ *ret_mode = mode;
+ if (ret_devno)
+ *ret_devno = devno;
+
+ return 0;
+}
+
+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_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 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_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 */
+ a->st_dev == b->st_dev &&
+ a->st_ino == b->st_ino &&
+ (!(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 */
+}
+
+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;
+}
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