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-rw-r--r--src/basic/path-util.c199
1 files changed, 0 insertions, 199 deletions
diff --git a/src/basic/path-util.c b/src/basic/path-util.c
index 7abb3a7b9e..b1cab7356c 100644
--- a/src/basic/path-util.c
+++ b/src/basic/path-util.c
@@ -454,205 +454,6 @@ char* path_join(const char *root, const char *path, const char *rest) {
NULL);
}
-static int fd_fdinfo_mnt_id(int fd, const char *filename, int flags, int *mnt_id) {
- char path[strlen("/proc/self/fdinfo/") + DECIMAL_STR_MAX(int)];
- _cleanup_free_ char *fdinfo = NULL;
- _cleanup_close_ int subfd = -1;
- char *p;
- int r;
-
- if ((flags & AT_EMPTY_PATH) && isempty(filename))
- xsprintf(path, "/proc/self/fdinfo/%i", fd);
- else {
- subfd = openat(fd, filename, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_PATH);
- if (subfd < 0)
- return -errno;
-
- xsprintf(path, "/proc/self/fdinfo/%i", subfd);
- }
-
- r = read_full_file(path, &fdinfo, NULL);
- if (r == -ENOENT) /* The fdinfo directory is a relatively new addition */
- return -EOPNOTSUPP;
- if (r < 0)
- return -errno;
-
- p = startswith(fdinfo, "mnt_id:");
- if (!p) {
- p = strstr(fdinfo, "\nmnt_id:");
- if (!p) /* The mnt_id field is a relatively new addition */
- return -EOPNOTSUPP;
-
- p += 8;
- }
-
- p += strspn(p, WHITESPACE);
- p[strcspn(p, WHITESPACE)] = 0;
-
- return safe_atoi(p, mnt_id);
-}
-
-int fd_is_mount_point(int fd, const char *filename, int flags) {
- union file_handle_union h = FILE_HANDLE_INIT, h_parent = FILE_HANDLE_INIT;
- int mount_id = -1, mount_id_parent = -1;
- bool nosupp = false, check_st_dev = true;
- struct stat a, b;
- int r;
-
- assert(fd >= 0);
- assert(filename);
-
- /* First we will try the name_to_handle_at() syscall, which
- * tells us the mount id and an opaque file "handle". It is
- * not supported everywhere though (kernel compile-time
- * option, not all file systems are hooked up). If it works
- * the mount id is usually good enough to tell us whether
- * something is a mount point.
- *
- * If that didn't work we will try to read the mount id from
- * /proc/self/fdinfo/<fd>. This is almost as good as
- * name_to_handle_at(), however, does not return the
- * opaque file handle. The opaque file handle is pretty useful
- * to detect the root directory, which we should always
- * consider a mount point. Hence we use this only as
- * fallback. Exporting the mnt_id in fdinfo is a pretty recent
- * kernel addition.
- *
- * As last fallback we do traditional fstat() based st_dev
- * comparisons. This is how things were traditionally done,
- * but unionfs breaks breaks this since it exposes file
- * systems with a variety of st_dev reported. Also, btrfs
- * subvolumes have different st_dev, even though they aren't
- * real mounts of their own. */
-
- r = name_to_handle_at(fd, filename, &h.handle, &mount_id, flags);
- if (r < 0) {
- if (errno == ENOSYS)
- /* This kernel does not support name_to_handle_at()
- * fall back to simpler logic. */
- goto fallback_fdinfo;
- else if (errno == EOPNOTSUPP)
- /* This kernel or file system does not support
- * name_to_handle_at(), hence let's see if the
- * upper fs supports it (in which case it is a
- * mount point), otherwise fallback to the
- * traditional stat() logic */
- nosupp = true;
- else
- return -errno;
- }
-
- r = name_to_handle_at(fd, "", &h_parent.handle, &mount_id_parent, AT_EMPTY_PATH);
- if (r < 0) {
- if (errno == EOPNOTSUPP) {
- if (nosupp)
- /* Neither parent nor child do name_to_handle_at()?
- We have no choice but to fall back. */
- goto fallback_fdinfo;
- else
- /* The parent can't do name_to_handle_at() but the
- * directory we are interested in can?
- * If so, it must be a mount point. */
- return 1;
- } else
- return -errno;
- }
-
- /* The parent can do name_to_handle_at() but the
- * directory we are interested in can't? If so, it
- * must be a mount point. */
- if (nosupp)
- return 1;
-
- /* If the file handle for the directory we are
- * interested in and its parent are identical, we
- * assume this is the root directory, which is a mount
- * point. */
-
- if (h.handle.handle_bytes == h_parent.handle.handle_bytes &&
- h.handle.handle_type == h_parent.handle.handle_type &&
- memcmp(h.handle.f_handle, h_parent.handle.f_handle, h.handle.handle_bytes) == 0)
- return 1;
-
- return mount_id != mount_id_parent;
-
-fallback_fdinfo:
- r = fd_fdinfo_mnt_id(fd, filename, flags, &mount_id);
- if (r == -EOPNOTSUPP)
- goto fallback_fstat;
- if (r < 0)
- return r;
-
- r = fd_fdinfo_mnt_id(fd, "", AT_EMPTY_PATH, &mount_id_parent);
- if (r < 0)
- return r;
-
- if (mount_id != mount_id_parent)
- return 1;
-
- /* Hmm, so, the mount ids are the same. This leaves one
- * special case though for the root file system. For that,
- * let's see if the parent directory has the same inode as we
- * are interested in. Hence, let's also do fstat() checks now,
- * too, but avoid the st_dev comparisons, since they aren't
- * that useful on unionfs mounts. */
- check_st_dev = false;
-
-fallback_fstat:
- /* yay for fstatat() taking a different set of flags than the other
- * _at() above */
- if (flags & AT_SYMLINK_FOLLOW)
- flags &= ~AT_SYMLINK_FOLLOW;
- else
- flags |= AT_SYMLINK_NOFOLLOW;
- if (fstatat(fd, filename, &a, flags) < 0)
- return -errno;
-
- if (fstatat(fd, "", &b, AT_EMPTY_PATH) < 0)
- return -errno;
-
- /* A directory with same device and inode as its parent? Must
- * be the root directory */
- if (a.st_dev == b.st_dev &&
- a.st_ino == b.st_ino)
- return 1;
-
- return check_st_dev && (a.st_dev != b.st_dev);
-}
-
-/* flags can be AT_SYMLINK_FOLLOW or 0 */
-int path_is_mount_point(const char *t, int flags) {
- _cleanup_close_ int fd = -1;
- _cleanup_free_ char *canonical = NULL, *parent = NULL;
-
- assert(t);
-
- if (path_equal(t, "/"))
- return 1;
-
- /* we need to resolve symlinks manually, we can't just rely on
- * fd_is_mount_point() to do that for us; if we have a structure like
- * /bin -> /usr/bin/ and /usr is a mount point, then the parent that we
- * look at needs to be /usr, not /. */
- if (flags & AT_SYMLINK_FOLLOW) {
- canonical = canonicalize_file_name(t);
- if (!canonical)
- return -errno;
-
- t = canonical;
- }
-
- parent = dirname_malloc(t);
- if (!parent)
- return -ENOMEM;
-
- fd = openat(AT_FDCWD, parent, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_PATH);
- if (fd < 0)
- return -errno;
-
- return fd_is_mount_point(fd, basename(t), flags);
-}
-
int path_is_read_only_fs(const char *path) {
struct statvfs st;
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-11-11 05:17:29 +0000