15308e5083
I mean, the old code at least used O_PATH, but still, we shouldn't allocate/close an fd if we don't have to.
473 lines
13 KiB
C
473 lines
13 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include <errno.h>
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#include <fcntl.h>
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#include <sched.h>
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#include <sys/statvfs.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include "alloc-util.h"
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#include "dirent-util.h"
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#include "fd-util.h"
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#include "fileio.h"
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#include "fs-util.h"
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#include "macro.h"
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#include "missing_fs.h"
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#include "missing_magic.h"
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#include "missing_syscall.h"
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#include "parse-util.h"
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#include "stat-util.h"
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#include "string-util.h"
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int is_symlink(const char *path) {
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struct stat info;
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assert(path);
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if (lstat(path, &info) < 0)
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return -errno;
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return !!S_ISLNK(info.st_mode);
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}
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int is_dir(const char* path, bool follow) {
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struct stat st;
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int r;
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assert(path);
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if (follow)
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r = stat(path, &st);
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else
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r = lstat(path, &st);
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if (r < 0)
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return -errno;
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return !!S_ISDIR(st.st_mode);
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}
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int is_dir_fd(int fd) {
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struct stat st;
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if (fstat(fd, &st) < 0)
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return -errno;
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return !!S_ISDIR(st.st_mode);
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}
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int is_device_node(const char *path) {
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struct stat info;
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assert(path);
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if (lstat(path, &info) < 0)
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return -errno;
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return !!(S_ISBLK(info.st_mode) || S_ISCHR(info.st_mode));
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}
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int dir_is_empty_at(int dir_fd, const char *path) {
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_cleanup_close_ int fd = -1;
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_cleanup_closedir_ DIR *d = NULL;
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struct dirent *de;
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if (path)
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fd = openat(dir_fd, path, O_RDONLY|O_DIRECTORY|O_CLOEXEC);
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else
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fd = fcntl(fd, F_DUPFD_CLOEXEC, 3);
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if (fd < 0)
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return -errno;
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d = take_fdopendir(&fd);
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if (!d)
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return -errno;
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FOREACH_DIRENT(de, d, return -errno)
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return 0;
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return 1;
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}
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bool null_or_empty(struct stat *st) {
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assert(st);
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if (S_ISREG(st->st_mode) && st->st_size <= 0)
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return true;
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/* We don't want to hardcode the major/minor of /dev/null, hence we do a simpler "is this a character
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* device node?" check. */
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if (S_ISCHR(st->st_mode))
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return true;
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return false;
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}
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int null_or_empty_path(const char *fn) {
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struct stat st;
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assert(fn);
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/* If we have the path, let's do an easy text comparison first. */
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if (path_equal(fn, "/dev/null"))
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return true;
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if (stat(fn, &st) < 0)
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return -errno;
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return null_or_empty(&st);
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}
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int null_or_empty_fd(int fd) {
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struct stat st;
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assert(fd >= 0);
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if (fstat(fd, &st) < 0)
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return -errno;
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return null_or_empty(&st);
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}
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int path_is_read_only_fs(const char *path) {
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struct statvfs st;
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assert(path);
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if (statvfs(path, &st) < 0)
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return -errno;
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if (st.f_flag & ST_RDONLY)
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return true;
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/* On NFS, statvfs() might not reflect whether we can actually
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* write to the remote share. Let's try again with
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* access(W_OK) which is more reliable, at least sometimes. */
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if (access(path, W_OK) < 0 && errno == EROFS)
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return true;
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return false;
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}
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int files_same(const char *filea, const char *fileb, int flags) {
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struct stat a, b;
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assert(filea);
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assert(fileb);
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if (fstatat(AT_FDCWD, filea, &a, flags) < 0)
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return -errno;
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if (fstatat(AT_FDCWD, fileb, &b, flags) < 0)
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return -errno;
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return a.st_dev == b.st_dev &&
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a.st_ino == b.st_ino;
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}
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bool is_fs_type(const struct statfs *s, statfs_f_type_t magic_value) {
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assert(s);
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assert_cc(sizeof(statfs_f_type_t) >= sizeof(s->f_type));
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return F_TYPE_EQUAL(s->f_type, magic_value);
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}
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int fd_is_fs_type(int fd, statfs_f_type_t magic_value) {
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struct statfs s;
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if (fstatfs(fd, &s) < 0)
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return -errno;
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return is_fs_type(&s, magic_value);
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}
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int path_is_fs_type(const char *path, statfs_f_type_t magic_value) {
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struct statfs s;
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if (statfs(path, &s) < 0)
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return -errno;
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return is_fs_type(&s, magic_value);
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}
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bool is_temporary_fs(const struct statfs *s) {
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return is_fs_type(s, TMPFS_MAGIC) ||
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is_fs_type(s, RAMFS_MAGIC);
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}
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bool is_network_fs(const struct statfs *s) {
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return is_fs_type(s, CIFS_MAGIC_NUMBER) ||
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is_fs_type(s, CODA_SUPER_MAGIC) ||
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is_fs_type(s, NCP_SUPER_MAGIC) ||
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is_fs_type(s, NFS_SUPER_MAGIC) ||
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is_fs_type(s, SMB_SUPER_MAGIC) ||
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is_fs_type(s, V9FS_MAGIC) ||
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is_fs_type(s, AFS_SUPER_MAGIC) ||
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is_fs_type(s, OCFS2_SUPER_MAGIC);
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}
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int fd_is_temporary_fs(int fd) {
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struct statfs s;
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if (fstatfs(fd, &s) < 0)
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return -errno;
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return is_temporary_fs(&s);
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}
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int fd_is_network_fs(int fd) {
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struct statfs s;
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if (fstatfs(fd, &s) < 0)
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return -errno;
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return is_network_fs(&s);
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}
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int path_is_temporary_fs(const char *path) {
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struct statfs s;
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if (statfs(path, &s) < 0)
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return -errno;
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return is_temporary_fs(&s);
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}
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int stat_verify_regular(const struct stat *st) {
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assert(st);
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/* Checks whether the specified stat() structure refers to a regular file. If not returns an appropriate error
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* code. */
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if (S_ISDIR(st->st_mode))
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return -EISDIR;
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if (S_ISLNK(st->st_mode))
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return -ELOOP;
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if (!S_ISREG(st->st_mode))
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return -EBADFD;
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return 0;
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}
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int fd_verify_regular(int fd) {
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struct stat st;
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assert(fd >= 0);
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if (fstat(fd, &st) < 0)
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return -errno;
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return stat_verify_regular(&st);
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}
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int stat_verify_directory(const struct stat *st) {
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assert(st);
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if (S_ISLNK(st->st_mode))
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return -ELOOP;
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if (!S_ISDIR(st->st_mode))
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return -ENOTDIR;
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return 0;
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}
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int fd_verify_directory(int fd) {
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struct stat st;
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assert(fd >= 0);
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if (fstat(fd, &st) < 0)
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return -errno;
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return stat_verify_directory(&st);
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}
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int device_path_make_major_minor(mode_t mode, dev_t devno, char **ret) {
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const char *t;
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/* Generates the /dev/{char|block}/MAJOR:MINOR path for a dev_t */
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if (S_ISCHR(mode))
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t = "char";
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else if (S_ISBLK(mode))
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t = "block";
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else
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return -ENODEV;
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if (asprintf(ret, "/dev/%s/%u:%u", t, major(devno), minor(devno)) < 0)
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return -ENOMEM;
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return 0;
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}
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int device_path_make_canonical(mode_t mode, dev_t devno, char **ret) {
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_cleanup_free_ char *p = NULL;
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int r;
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/* Finds the canonical path for a device, i.e. resolves the /dev/{char|block}/MAJOR:MINOR path to the end. */
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assert(ret);
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if (major(devno) == 0 && minor(devno) == 0) {
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char *s;
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/* A special hack to make sure our 'inaccessible' device nodes work. They won't have symlinks in
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* /dev/block/ and /dev/char/, hence we handle them specially here. */
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if (S_ISCHR(mode))
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s = strdup("/run/systemd/inaccessible/chr");
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else if (S_ISBLK(mode))
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s = strdup("/run/systemd/inaccessible/blk");
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else
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return -ENODEV;
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if (!s)
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return -ENOMEM;
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*ret = s;
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return 0;
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}
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r = device_path_make_major_minor(mode, devno, &p);
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if (r < 0)
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return r;
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return chase_symlinks(p, NULL, 0, ret, NULL);
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}
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int device_path_parse_major_minor(const char *path, mode_t *ret_mode, dev_t *ret_devno) {
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mode_t mode;
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dev_t devno;
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int r;
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/* Tries to extract the major/minor directly from the device path if we can. Handles /dev/block/ and /dev/char/
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* paths, as well out synthetic inaccessible device nodes. Never goes to disk. Returns -ENODEV if the device
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* path cannot be parsed like this. */
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if (path_equal(path, "/run/systemd/inaccessible/chr")) {
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mode = S_IFCHR;
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devno = makedev(0, 0);
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} else if (path_equal(path, "/run/systemd/inaccessible/blk")) {
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mode = S_IFBLK;
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devno = makedev(0, 0);
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} else {
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const char *w;
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w = path_startswith(path, "/dev/block/");
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if (w)
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mode = S_IFBLK;
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else {
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w = path_startswith(path, "/dev/char/");
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if (!w)
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return -ENODEV;
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mode = S_IFCHR;
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}
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r = parse_dev(w, &devno);
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if (r < 0)
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return r;
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}
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if (ret_mode)
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*ret_mode = mode;
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if (ret_devno)
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*ret_devno = devno;
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return 0;
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}
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int proc_mounted(void) {
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int r;
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/* A quick check of procfs is properly mounted */
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r = path_is_fs_type("/proc/", PROC_SUPER_MAGIC);
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if (r == -ENOENT) /* not mounted at all */
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return false;
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return r;
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}
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bool stat_inode_unmodified(const struct stat *a, const struct stat *b) {
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/* Returns if the specified stat structures reference the same, unmodified inode. This check tries to
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* be reasonably careful when detecting changes: we check both inode and mtime, to cater for file
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* systems where mtimes are fixed to 0 (think: ostree/nixos type installations). We also check file
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* size, backing device, inode type and if this refers to a device not the major/minor.
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*
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* Note that we don't care if file attributes such as ownership or access mode change, this here is
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* about contents of the file. The purpose here is to detect file contents changes, and nothing
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* else. */
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return a && b &&
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(a->st_mode & S_IFMT) != 0 && /* We use the check for .st_mode if the structure was ever initialized */
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((a->st_mode ^ b->st_mode) & S_IFMT) == 0 && /* same inode type */
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a->st_mtim.tv_sec == b->st_mtim.tv_sec &&
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a->st_mtim.tv_nsec == b->st_mtim.tv_nsec &&
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(!S_ISREG(a->st_mode) || a->st_size == b->st_size) && /* if regular file, compare file size */
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a->st_dev == b->st_dev &&
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a->st_ino == b->st_ino &&
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(!(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 */
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}
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int statx_fallback(int dfd, const char *path, int flags, unsigned mask, struct statx *sx) {
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static bool avoid_statx = false;
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struct stat st;
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if (!avoid_statx) {
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if (statx(dfd, path, flags, mask, sx) < 0) {
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if (!ERRNO_IS_NOT_SUPPORTED(errno) && errno != EPERM)
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return -errno;
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/* If statx() is not supported or if we see EPERM (which might indicate seccomp
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* filtering or so), let's do a fallback. Not that on EACCES we'll not fall back,
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* since that is likely an indication of fs access issues, which we should
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* propagate */
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} else
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return 0;
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avoid_statx = true;
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}
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/* Only do fallback if fstatat() supports the flag too, or if it's one of the sync flags, which are
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* OK to ignore */
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if ((flags & ~(AT_EMPTY_PATH|AT_NO_AUTOMOUNT|AT_SYMLINK_NOFOLLOW|
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AT_STATX_SYNC_AS_STAT|AT_STATX_FORCE_SYNC|AT_STATX_DONT_SYNC)) != 0)
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return -EOPNOTSUPP;
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if (fstatat(dfd, path, &st, flags & (AT_EMPTY_PATH|AT_NO_AUTOMOUNT|AT_SYMLINK_NOFOLLOW)) < 0)
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return -errno;
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*sx = (struct statx) {
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.stx_mask = STATX_TYPE|STATX_MODE|
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STATX_NLINK|STATX_UID|STATX_GID|
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STATX_ATIME|STATX_MTIME|STATX_CTIME|
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STATX_INO|STATX_SIZE|STATX_BLOCKS,
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.stx_blksize = st.st_blksize,
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.stx_nlink = st.st_nlink,
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.stx_uid = st.st_uid,
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.stx_gid = st.st_gid,
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.stx_mode = st.st_mode,
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.stx_ino = st.st_ino,
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.stx_size = st.st_size,
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.stx_blocks = st.st_blocks,
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.stx_rdev_major = major(st.st_rdev),
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.stx_rdev_minor = minor(st.st_rdev),
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.stx_dev_major = major(st.st_dev),
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.stx_dev_minor = minor(st.st_dev),
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.stx_atime.tv_sec = st.st_atim.tv_sec,
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.stx_atime.tv_nsec = st.st_atim.tv_nsec,
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.stx_mtime.tv_sec = st.st_mtim.tv_sec,
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.stx_mtime.tv_nsec = st.st_mtim.tv_nsec,
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.stx_ctime.tv_sec = st.st_ctim.tv_sec,
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.stx_ctime.tv_nsec = st.st_ctim.tv_nsec,
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};
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return 0;
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}
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