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-rw-r--r--src/basic/stat-util.c427
1 files changed, 427 insertions, 0 deletions
diff --git a/src/basic/stat-util.c b/src/basic/stat-util.c
new file mode 100644
index 0000000..ea2bbc3
--- /dev/null
+++ b/src/basic/stat-util.c
@@ -0,0 +1,427 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/magic.h>
+#include <sched.h>
+#include <sys/stat.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 "fs-util.h"
+#include "macro.h"
+#include "missing.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 = fdopendir(fd);
+ if (!d)
+ return -errno;
+ fd = -1;
+
+ 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 device node?" check. */
+
+ if (S_ISCHR(st->st_mode) || S_ISBLK(st->st_mode))
+ return true;
+
+ return false;
+}
+
+int null_or_empty_path(const char *fn) {
+ struct stat st;
+
+ assert(fn);
+
+ 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) {
+ _cleanup_close_ int fd = -1;
+
+ fd = open(path, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_PATH);
+ if (fd < 0)
+ return -errno;
+
+ return fd_is_fs_type(fd, 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 fd_is_network_ns(int fd) {
+ struct statfs s;
+ int r;
+
+ /* Checks whether the specified file descriptor refers to a network namespace. On old kernels there's no nice
+ * way to detect that, hence on those we'll return a recognizable error (EUCLEAN), so that callers can handle
+ * this somewhat nicely.
+ *
+ * This function returns > 0 if the fd definitely refers to a network namespace, 0 if it definitely does not
+ * refer to a network namespace, -EUCLEAN if we can't determine, and other negative error codes on error. */
+
+ if (fstatfs(fd, &s) < 0)
+ return -errno;
+
+ if (!is_fs_type(&s, NSFS_MAGIC)) {
+ /* On really old kernels, there was no "nsfs", and network namespace sockets belonged to procfs
+ * instead. Handle that in a somewhat smart way. */
+
+ if (is_fs_type(&s, PROC_SUPER_MAGIC)) {
+ struct statfs t;
+
+ /* OK, so it is procfs. Let's see if our own network namespace is procfs, too. If so, then the
+ * passed fd might refer to a network namespace, but we can't know for sure. In that case,
+ * return a recognizable error. */
+
+ if (statfs("/proc/self/ns/net", &t) < 0)
+ return -errno;
+
+ if (s.f_type == t.f_type)
+ return -EUCLEAN; /* It's possible, we simply don't know */
+ }
+
+ return 0; /* No! */
+ }
+
+ r = ioctl(fd, NS_GET_NSTYPE);
+ if (r < 0) {
+ if (errno == ENOTTY) /* Old kernels didn't know this ioctl, let's also return a recognizable error in that case */
+ return -EUCLEAN;
+
+ return -errno;
+ }
+
+ return r == CLONE_NEWNET;
+}
+
+int path_is_temporary_fs(const char *path) {
+ _cleanup_close_ int fd = -1;
+
+ fd = open(path, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_PATH);
+ if (fd < 0)
+ return -errno;
+
+ return fd_is_temporary_fs(fd);
+}
+
+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);
+}
+
+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;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-08-13 12:01:19 +0000