]>
git.ipfire.org Git - thirdparty/systemd.git/blob - src/basic/fd-util.c
1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
8 #include <linux/magic.h>
10 #include <sys/resource.h>
14 #include "alloc-util.h"
15 #include "dirent-util.h"
21 #include "missing_fcntl.h"
22 #include "missing_fs.h"
23 #include "missing_syscall.h"
24 #include "mountpoint-util.h"
25 #include "parse-util.h"
26 #include "path-util.h"
27 #include "process-util.h"
28 #include "socket-util.h"
29 #include "sort-util.h"
30 #include "stat-util.h"
31 #include "stdio-util.h"
32 #include "tmpfile-util.h"
34 /* The maximum number of iterations in the loop to close descriptors in the fallback case
35 * when /proc/self/fd/ is inaccessible. */
36 #define MAX_FD_LOOP_LIMIT (1024*1024)
38 int close_nointr(int fd
) {
45 * Just ignore EINTR; a retry loop is the wrong thing to do on
48 * http://lkml.indiana.edu/hypermail/linux/kernel/0509.1/0877.html
49 * https://bugzilla.gnome.org/show_bug.cgi?id=682819
50 * http://utcc.utoronto.ca/~cks/space/blog/unix/CloseEINTR
51 * https://sites.google.com/site/michaelsafyan/software-engineering/checkforeintrwheninvokingclosethinkagain
59 int safe_close(int fd
) {
61 * Like close_nointr() but cannot fail. Guarantees errno is unchanged. Is a noop for negative fds,
62 * and returns -EBADF, so that it can be used in this syntax:
64 * fd = safe_close(fd);
70 /* The kernel might return pretty much any error code
71 * via close(), but the fd will be closed anyway. The
72 * only condition we want to check for here is whether
73 * the fd was invalid at all... */
75 assert_se(close_nointr(fd
) != -EBADF
);
81 void safe_close_pair(int p
[static 2]) {
85 /* Special case pairs which use the same fd in both
87 p
[0] = p
[1] = safe_close(p
[0]);
91 p
[0] = safe_close(p
[0]);
92 p
[1] = safe_close(p
[1]);
95 void close_many(const int fds
[], size_t n_fd
) {
96 assert(fds
|| n_fd
<= 0);
98 for (size_t i
= 0; i
< n_fd
; i
++)
102 int fclose_nointr(FILE *f
) {
105 /* Same as close_nointr(), but for fclose() */
107 errno
= 0; /* Extra safety: if the FILE* object is not encapsulating an fd, it might not set errno
108 * correctly. Let's hence initialize it to zero first, so that we aren't confused by any
109 * prior errno here */
116 return errno_or_else(EIO
);
119 FILE* safe_fclose(FILE *f
) {
121 /* Same as safe_close(), but for fclose() */
126 assert_se(fclose_nointr(f
) != -EBADF
);
132 DIR* safe_closedir(DIR *d
) {
137 assert_se(closedir(d
) >= 0 || errno
!= EBADF
);
143 int fd_nonblock(int fd
, bool nonblock
) {
148 flags
= fcntl(fd
, F_GETFL
, 0);
152 nflags
= UPDATE_FLAG(flags
, O_NONBLOCK
, nonblock
);
156 return RET_NERRNO(fcntl(fd
, F_SETFL
, nflags
));
159 int fd_cloexec(int fd
, bool cloexec
) {
164 flags
= fcntl(fd
, F_GETFD
, 0);
168 nflags
= UPDATE_FLAG(flags
, FD_CLOEXEC
, cloexec
);
172 return RET_NERRNO(fcntl(fd
, F_SETFD
, nflags
));
175 int fd_cloexec_many(const int fds
[], size_t n_fds
, bool cloexec
) {
178 assert(n_fds
== 0 || fds
);
180 for (size_t i
= 0; i
< n_fds
; i
++) {
181 if (fds
[i
] < 0) /* Skip gracefully over already invalidated fds */
184 r
= fd_cloexec(fds
[i
], cloexec
);
185 if (r
< 0 && ret
>= 0) /* Continue going, but return first error */
188 ret
= 1; /* report if we did anything */
194 static bool fd_in_set(int fd
, const int fdset
[], size_t n_fdset
) {
195 assert(n_fdset
== 0 || fdset
);
197 for (size_t i
= 0; i
< n_fdset
; i
++) {
208 int get_max_fd(void) {
212 /* Return the highest possible fd, based RLIMIT_NOFILE, but enforcing FD_SETSIZE-1 as lower boundary
213 * and INT_MAX as upper boundary. */
215 if (getrlimit(RLIMIT_NOFILE
, &rl
) < 0)
218 m
= MAX(rl
.rlim_cur
, rl
.rlim_max
);
219 if (m
< FD_SETSIZE
) /* Let's always cover at least 1024 fds */
222 if (m
== RLIM_INFINITY
|| m
> INT_MAX
) /* Saturate on overflow. After all fds are "int", hence can
223 * never be above INT_MAX */
226 return (int) (m
- 1);
229 static int close_all_fds_frugal(const int except
[], size_t n_except
) {
232 assert(n_except
== 0 || except
);
234 /* This is the inner fallback core of close_all_fds(). This never calls malloc() or opendir() or so
235 * and hence is safe to be called in signal handler context. Most users should call close_all_fds(),
236 * but when we assume we are called from signal handler context, then use this simpler call
239 max_fd
= get_max_fd();
243 /* Refuse to do the loop over more too many elements. It's better to fail immediately than to
244 * spin the CPU for a long time. */
245 if (max_fd
> MAX_FD_LOOP_LIMIT
)
246 return log_debug_errno(SYNTHETIC_ERRNO(EPERM
),
247 "Refusing to loop over %d potential fds.",
250 for (int fd
= 3; fd
>= 0; fd
= fd
< max_fd
? fd
+ 1 : -EBADF
) {
253 if (fd_in_set(fd
, except
, n_except
))
256 q
= close_nointr(fd
);
257 if (q
< 0 && q
!= -EBADF
&& r
>= 0)
264 static bool have_close_range
= true; /* Assume we live in the future */
266 static int close_all_fds_special_case(const int except
[], size_t n_except
) {
267 assert(n_except
== 0 || except
);
269 /* Handles a few common special cases separately, since they are common and can be optimized really
270 * nicely, since we won't need sorting for them. Returns > 0 if the special casing worked, 0
273 if (!have_close_range
)
276 if (n_except
== 1 && except
[0] < 0) /* Minor optimization: if we only got one fd, and it's invalid,
283 /* Close everything. Yay! */
285 if (close_range(3, -1, 0) >= 0)
288 if (ERRNO_IS_NOT_SUPPORTED(errno
) || ERRNO_IS_PRIVILEGE(errno
)) {
289 have_close_range
= false;
296 /* Close all but exactly one, then we don't need no sorting. This is a pretty common
297 * case, hence let's handle it specially. */
299 if ((except
[0] <= 3 || close_range(3, except
[0]-1, 0) >= 0) &&
300 (except
[0] >= INT_MAX
|| close_range(MAX(3, except
[0]+1), -1, 0) >= 0))
303 if (ERRNO_IS_NOT_SUPPORTED(errno
) || ERRNO_IS_PRIVILEGE(errno
)) {
304 have_close_range
= false;
315 int close_all_fds_without_malloc(const int except
[], size_t n_except
) {
318 assert(n_except
== 0 || except
);
320 r
= close_all_fds_special_case(except
, n_except
);
323 if (r
> 0) /* special case worked! */
326 return close_all_fds_frugal(except
, n_except
);
329 int close_all_fds(const int except
[], size_t n_except
) {
330 _cleanup_closedir_
DIR *d
= NULL
;
333 assert(n_except
== 0 || except
);
335 r
= close_all_fds_special_case(except
, n_except
);
338 if (r
> 0) /* special case worked! */
341 if (have_close_range
) {
342 _cleanup_free_
int *sorted_malloc
= NULL
;
346 /* In the best case we have close_range() to close all fds between a start and an end fd,
347 * which we can use on the "inverted" exception array, i.e. all intervals between all
348 * adjacent pairs from the sorted exception array. This changes loop complexity from O(n)
349 * where n is number of open fds to O(mâ‹…log(m)) where m is the number of fds to keep
350 * open. Given that we assume n ≫ m that's preferable to us. */
352 assert(n_except
< SIZE_MAX
);
353 n_sorted
= n_except
+ 1;
355 if (n_sorted
> 64) /* Use heap for large numbers of fds, stack otherwise */
356 sorted
= sorted_malloc
= new(int, n_sorted
);
358 sorted
= newa(int, n_sorted
);
361 memcpy(sorted
, except
, n_except
* sizeof(int));
363 /* Let's add fd 2 to the list of fds, to simplify the loop below, as this
364 * allows us to cover the head of the array the same way as the body */
365 sorted
[n_sorted
-1] = 2;
367 typesafe_qsort(sorted
, n_sorted
, cmp_int
);
369 for (size_t i
= 0; i
< n_sorted
-1; i
++) {
372 start
= MAX(sorted
[i
], 2); /* The first three fds shall always remain open */
373 end
= MAX(sorted
[i
+1], 2);
375 assert(end
>= start
);
377 if (end
- start
<= 1)
380 /* Close everything between the start and end fds (both of which shall stay open) */
381 if (close_range(start
+ 1, end
- 1, 0) < 0) {
382 if (!ERRNO_IS_NOT_SUPPORTED(errno
) && !ERRNO_IS_PRIVILEGE(errno
))
385 have_close_range
= false;
390 if (have_close_range
) {
391 /* The loop succeeded. Let's now close everything beyond the end */
393 if (sorted
[n_sorted
-1] >= INT_MAX
) /* Dont let the addition below overflow */
396 if (close_range(sorted
[n_sorted
-1] + 1, -1, 0) >= 0)
399 if (!ERRNO_IS_NOT_SUPPORTED(errno
) && !ERRNO_IS_PRIVILEGE(errno
))
402 have_close_range
= false;
406 /* Fallback on OOM or if close_range() is not supported */
409 d
= opendir("/proc/self/fd");
411 return close_all_fds_frugal(except
, n_except
); /* ultimate fallback if /proc/ is not available */
413 FOREACH_DIRENT(de
, d
, return -errno
) {
416 if (!IN_SET(de
->d_type
, DT_LNK
, DT_UNKNOWN
))
419 fd
= parse_fd(de
->d_name
);
421 /* Let's better ignore this, just in case */
430 if (fd_in_set(fd
, except
, n_except
))
433 q
= close_nointr(fd
);
434 if (q
< 0 && q
!= -EBADF
&& r
>= 0) /* Valgrind has its own FD and doesn't want to have it closed */
441 int same_fd(int a
, int b
) {
442 struct stat sta
, stb
;
449 /* Compares two file descriptors. Note that semantics are quite different depending on whether we
450 * have kcmp() or we don't. If we have kcmp() this will only return true for dup()ed file
451 * descriptors, but not otherwise. If we don't have kcmp() this will also return true for two fds of
452 * the same file, created by separate open() calls. Since we use this call mostly for filtering out
453 * duplicates in the fd store this difference hopefully doesn't matter too much. */
458 /* Try to use kcmp() if we have it. */
459 pid
= getpid_cached();
460 r
= kcmp(pid
, pid
, KCMP_FILE
, a
, b
);
465 if (!ERRNO_IS_NOT_SUPPORTED(errno
) && !ERRNO_IS_PRIVILEGE(errno
))
468 /* We don't have kcmp(), use fstat() instead. */
469 if (fstat(a
, &sta
) < 0)
472 if (fstat(b
, &stb
) < 0)
475 if (!stat_inode_same(&sta
, &stb
))
478 /* We consider all device fds different, since two device fds might refer to quite different device
479 * contexts even though they share the same inode and backing dev_t. */
481 if (S_ISCHR(sta
.st_mode
) || S_ISBLK(sta
.st_mode
))
484 /* The fds refer to the same inode on disk, let's also check if they have the same fd flags. This is
485 * useful to distinguish the read and write side of a pipe created with pipe(). */
486 fa
= fcntl(a
, F_GETFL
);
490 fb
= fcntl(b
, F_GETFL
);
497 void cmsg_close_all(struct msghdr
*mh
) {
498 struct cmsghdr
*cmsg
;
502 CMSG_FOREACH(cmsg
, mh
)
503 if (cmsg
->cmsg_level
== SOL_SOCKET
&& cmsg
->cmsg_type
== SCM_RIGHTS
)
504 close_many(CMSG_TYPED_DATA(cmsg
, int),
505 (cmsg
->cmsg_len
- CMSG_LEN(0)) / sizeof(int));
508 bool fdname_is_valid(const char *s
) {
511 /* Validates a name for $LISTEN_FDNAMES. We basically allow
512 * everything ASCII that's not a control character. Also, as
513 * special exception the ":" character is not allowed, as we
514 * use that as field separator in $LISTEN_FDNAMES.
516 * Note that the empty string is explicitly allowed
517 * here. However, we limit the length of the names to 255
523 for (p
= s
; *p
; p
++) {
532 return p
- s
<= FDNAME_MAX
;
535 int fd_get_path(int fd
, char **ret
) {
538 assert(fd
>= 0 || fd
== AT_FDCWD
);
541 return safe_getcwd(ret
);
543 r
= readlink_malloc(FORMAT_PROC_FD_PATH(fd
), ret
);
545 /* ENOENT can mean two things: that the fd does not exist or that /proc is not mounted. Let's make
546 * things debuggable and distinguish the two. */
548 if (proc_mounted() == 0)
549 return -ENOSYS
; /* /proc is not available or not set up properly, we're most likely in some chroot
551 return -EBADF
; /* The directory exists, hence it's the fd that doesn't. */
557 int move_fd(int from
, int to
, int cloexec
) {
560 /* Move fd 'from' to 'to', make sure FD_CLOEXEC remains equal if requested, and release the old fd. If
561 * 'cloexec' is passed as -1, the original FD_CLOEXEC is inherited for the new fd. If it is 0, it is turned
562 * off, if it is > 0 it is turned on. */
572 r
= fd_cloexec(to
, cloexec
);
583 fl
= fcntl(from
, F_GETFD
, 0);
587 cloexec
= !!(fl
& FD_CLOEXEC
);
590 r
= dup3(from
, to
, cloexec
? O_CLOEXEC
: 0);
601 int fd_move_above_stdio(int fd
) {
605 /* Moves the specified file descriptor if possible out of the range [0…2], i.e. the range of
606 * stdin/stdout/stderr. If it can't be moved outside of this range the original file descriptor is
607 * returned. This call is supposed to be used for long-lasting file descriptors we allocate in our code that
608 * might get loaded into foreign code, and where we want ensure our fds are unlikely used accidentally as
609 * stdin/stdout/stderr of unrelated code.
611 * Note that this doesn't fix any real bugs, it just makes it less likely that our code will be affected by
612 * buggy code from others that mindlessly invokes 'fprintf(stderr, …' or similar in places where stderr has
613 * been closed before.
615 * This function is written in a "best-effort" and "least-impact" style. This means whenever we encounter an
616 * error we simply return the original file descriptor, and we do not touch errno. */
618 if (fd
< 0 || fd
> 2)
621 flags
= fcntl(fd
, F_GETFD
, 0);
625 if (flags
& FD_CLOEXEC
)
626 copy
= fcntl(fd
, F_DUPFD_CLOEXEC
, 3);
628 copy
= fcntl(fd
, F_DUPFD
, 3);
638 int rearrange_stdio(int original_input_fd
, int original_output_fd
, int original_error_fd
) {
639 int fd
[3] = { original_input_fd
, /* Put together an array of fds we work on */
642 null_fd
= -EBADF
, /* If we open /dev/null, we store the fd to it here */
643 copy_fd
[3] = { -EBADF
, -EBADF
, -EBADF
}, /* This contains all fds we duplicate here
644 * temporarily, and hence need to close at the end. */
646 bool null_readable
, null_writable
;
648 /* Sets up stdin, stdout, stderr with the three file descriptors passed in. If any of the descriptors
649 * is specified as -EBADF it will be connected with /dev/null instead. If any of the file descriptors
650 * is passed as itself (e.g. stdin as STDIN_FILENO) it is left unmodified, but the O_CLOEXEC bit is
651 * turned off should it be on.
653 * Note that if any of the passed file descriptors are > 2 they will be closed — both on success and
654 * on failure! Thus, callers should assume that when this function returns the input fds are
657 * Note that when this function fails stdin/stdout/stderr might remain half set up!
659 * O_CLOEXEC is turned off for all three file descriptors (which is how it should be for
660 * stdin/stdout/stderr). */
662 null_readable
= original_input_fd
< 0;
663 null_writable
= original_output_fd
< 0 || original_error_fd
< 0;
665 /* First step, open /dev/null once, if we need it */
666 if (null_readable
|| null_writable
) {
668 /* Let's open this with O_CLOEXEC first, and convert it to non-O_CLOEXEC when we move the fd to the final position. */
669 null_fd
= open("/dev/null", (null_readable
&& null_writable
? O_RDWR
:
670 null_readable
? O_RDONLY
: O_WRONLY
) | O_CLOEXEC
);
676 /* If this fd is in the 0…2 range, let's move it out of it */
680 copy
= fcntl(null_fd
, F_DUPFD_CLOEXEC
, 3); /* Duplicate this with O_CLOEXEC set */
686 close_and_replace(null_fd
, copy
);
690 /* Let's assemble fd[] with the fds to install in place of stdin/stdout/stderr */
691 for (int i
= 0; i
< 3; i
++) {
694 fd
[i
] = null_fd
; /* A negative parameter means: connect this one to /dev/null */
695 else if (fd
[i
] != i
&& fd
[i
] < 3) {
696 /* This fd is in the 0…2 territory, but not at its intended place, move it out of there, so that we can work there. */
697 copy_fd
[i
] = fcntl(fd
[i
], F_DUPFD_CLOEXEC
, 3); /* Duplicate this with O_CLOEXEC set */
698 if (copy_fd
[i
] < 0) {
707 /* At this point we now have the fds to use in fd[], and they are all above the stdio range, so that
708 * we have freedom to move them around. If the fds already were at the right places then the specific
709 * fds are -EBADF. Let's now move them to the right places. This is the point of no return. */
710 for (int i
= 0; i
< 3; i
++) {
714 /* fd is already in place, but let's make sure O_CLOEXEC is off */
715 r
= fd_cloexec(i
, false);
722 if (dup2(fd
[i
], i
) < 0) { /* Turns off O_CLOEXEC on the new fd. */
732 /* Close the original fds, but only if they were outside of the stdio range. Also, properly check for the same
733 * fd passed in multiple times. */
734 safe_close_above_stdio(original_input_fd
);
735 if (original_output_fd
!= original_input_fd
)
736 safe_close_above_stdio(original_output_fd
);
737 if (original_error_fd
!= original_input_fd
&& original_error_fd
!= original_output_fd
)
738 safe_close_above_stdio(original_error_fd
);
740 /* Close the copies we moved > 2 */
741 for (int i
= 0; i
< 3; i
++)
742 safe_close(copy_fd
[i
]);
744 /* Close our null fd, if it's > 2 */
745 safe_close_above_stdio(null_fd
);
750 int fd_reopen(int fd
, int flags
) {
753 assert(fd
>= 0 || fd
== AT_FDCWD
);
755 /* Reopens the specified fd with new flags. This is useful for convert an O_PATH fd into a regular one, or to
756 * turn O_RDWR fds into O_RDONLY fds.
758 * This doesn't work on sockets (since they cannot be open()ed, ever).
760 * This implicitly resets the file read index to 0.
762 * If AT_FDCWD is specified as file descriptor gets an fd to the current cwd.
764 * If the specified file descriptor refers to a symlink via O_PATH, then this function cannot be used
765 * to follow that symlink. Because we cannot have non-O_PATH fds to symlinks reopening it without
766 * O_PATH will always result in -ELOOP. Or in other words: if you have an O_PATH fd to a symlink you
767 * can reopen it only if you pass O_PATH again. */
769 if (FLAGS_SET(flags
, O_NOFOLLOW
))
770 /* O_NOFOLLOW is not allowed in fd_reopen(), because after all this is primarily implemented
771 * via a symlink-based interface in /proc/self/fd. Let's refuse this here early. Note that
772 * the kernel would generate ELOOP here too, hence this manual check is mostly redundant –
773 * the only reason we add it here is so that the O_DIRECTORY special case (see below) behaves
774 * the same way as the non-O_DIRECTORY case. */
777 if (FLAGS_SET(flags
, O_DIRECTORY
) || fd
== AT_FDCWD
) {
778 /* If we shall reopen the fd as directory we can just go via "." and thus bypass the whole
779 * magic /proc/ directory, and make ourselves independent of that being mounted. */
780 new_fd
= openat(fd
, ".", flags
| O_DIRECTORY
);
789 new_fd
= open(FORMAT_PROC_FD_PATH(fd
), flags
);
796 return -ENOSYS
; /* if we have no /proc/, the concept is not implementable */
798 return r
> 0 ? -EBADF
: -ENOENT
; /* If /proc/ is definitely around then this means the fd is
799 * not valid, otherwise let's propagate the original
806 int fd_reopen_condition(
816 /* Invokes fd_reopen(fd, flags), but only if the existing F_GETFL flags don't match the specified
817 * flags (masked by the specified mask). This is useful for converting O_PATH fds into real fds if
818 * needed, but only then. */
820 r
= fcntl(fd
, F_GETFL
);
824 if ((r
& mask
) == (flags
& mask
)) {
825 *ret_new_fd
= -EBADF
;
829 new_fd
= fd_reopen(fd
, flags
);
833 *ret_new_fd
= new_fd
;
837 int fd_is_opath(int fd
) {
842 r
= fcntl(fd
, F_GETFL
);
846 return FLAGS_SET(r
, O_PATH
);
849 int read_nr_open(void) {
850 _cleanup_free_
char *nr_open
= NULL
;
853 /* Returns the kernel's current fd limit, either by reading it of /proc/sys if that works, or using the
854 * hard-coded default compiled-in value of current kernels (1M) if not. This call will never fail. */
856 r
= read_one_line_file("/proc/sys/fs/nr_open", &nr_open
);
858 log_debug_errno(r
, "Failed to read /proc/sys/fs/nr_open, ignoring: %m");
862 r
= safe_atoi(nr_open
, &v
);
864 log_debug_errno(r
, "Failed to parse /proc/sys/fs/nr_open value '%s', ignoring: %m", nr_open
);
869 /* If we fail, fall back to the hard-coded kernel limit of 1024 * 1024. */
873 int fd_get_diskseq(int fd
, uint64_t *ret
) {
879 if (ioctl(fd
, BLKGETDISKSEQ
, &diskseq
) < 0) {
880 /* Note that the kernel is weird: non-existing ioctls currently return EINVAL
881 * rather than ENOTTY on loopback block devices. They should fix that in the kernel,
882 * but in the meantime we accept both here. */
883 if (!ERRNO_IS_NOT_SUPPORTED(errno
) && errno
!= EINVAL
)
894 int path_is_root_at(int dir_fd
, const char *path
) {
895 STRUCT_NEW_STATX_DEFINE(st
);
896 STRUCT_NEW_STATX_DEFINE(pst
);
897 _cleanup_close_
int fd
= -EBADF
;
900 assert(dir_fd
>= 0 || dir_fd
== AT_FDCWD
);
902 if (!isempty(path
)) {
903 fd
= openat(dir_fd
, path
, O_PATH
|O_DIRECTORY
|O_CLOEXEC
);
905 return errno
== ENOTDIR
? false : -errno
;
910 r
= statx_fallback(dir_fd
, ".", 0, STATX_TYPE
|STATX_INO
|STATX_MNT_ID
, &st
.sx
);
916 r
= statx_fallback(dir_fd
, "..", 0, STATX_TYPE
|STATX_INO
|STATX_MNT_ID
, &pst
.sx
);
920 /* First, compare inode. If these are different, the fd does not point to the root directory "/". */
921 if (!statx_inode_same(&st
.sx
, &pst
.sx
))
924 /* Even if the parent directory has the same inode, the fd may not point to the root directory "/",
925 * and we also need to check that the mount ids are the same. Otherwise, a construct like the
926 * following could be used to trick us:
928 * $ mkdir /tmp/x /tmp/x/y
929 * $ mount --bind /tmp/x /tmp/x/y
931 * Note, statx() does not provide the mount ID and path_get_mnt_id_at() does not work when an old
932 * kernel is used. In that case, let's assume that we do not have such spurious mount points in an
933 * early boot stage, and silently skip the following check. */
935 if (!FLAGS_SET(st
.nsx
.stx_mask
, STATX_MNT_ID
)) {
938 r
= path_get_mnt_id_at_fallback(dir_fd
, "", &mntid
);
939 if (ERRNO_IS_NEG_NOT_SUPPORTED(r
))
940 return true; /* skip the mount ID check */
945 st
.nsx
.stx_mnt_id
= mntid
;
946 st
.nsx
.stx_mask
|= STATX_MNT_ID
;
949 if (!FLAGS_SET(pst
.nsx
.stx_mask
, STATX_MNT_ID
)) {
952 r
= path_get_mnt_id_at_fallback(dir_fd
, "..", &mntid
);
953 if (ERRNO_IS_NEG_NOT_SUPPORTED(r
))
954 return true; /* skip the mount ID check */
959 pst
.nsx
.stx_mnt_id
= mntid
;
960 pst
.nsx
.stx_mask
|= STATX_MNT_ID
;
963 return statx_mount_same(&st
.nsx
, &pst
.nsx
);
966 const char *accmode_to_string(int flags
) {
967 switch (flags
& O_ACCMODE
) {