tools/testing/selftests/tmpfs/bug-link-o-tmpfile.c

   1 /*
   2  * Copyright (c) 2019 Alexey Dobriyan <adobriyan@gmail.com>
   3  *
   4  * Permission to use, copy, modify, and distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15  */
  16 /* Test that open(O_TMPFILE), linkat() doesn't screw accounting. */
  17 #include <errno.h>
  18 #include <sched.h>
  19 #include <stdio.h>
  20 #include <sys/types.h>
  21 #include <sys/stat.h>
  22 #include <fcntl.h>
  23 #include <sys/mount.h>
  24 #include <unistd.h>
  25
  26 int main(void)
  27 {
  28         int fd;
  29
  30         if (unshare(CLONE_NEWNS) == -1) {
  31                 if (errno == ENOSYS || errno == EPERM) {
  32                         fprintf(stderr, "error: unshare, errno %d\n", errno);
  33                         return 4;
  34                 }
  35                 fprintf(stderr, "error: unshare, errno %d\n", errno);
  36                 return 1;
  37         }
  38         if (mount(NULL, "/", NULL, MS_PRIVATE|MS_REC, NULL) == -1) {
  39                 fprintf(stderr, "error: mount '/', errno %d\n", errno);
  40                 return 1;
  41         }
  42
  43         /* Our heroes: 1 root inode, 1 O_TMPFILE inode, 1 permanent inode. */
  44         if (mount(NULL, "/tmp", "tmpfs", 0, "nr_inodes=3") == -1) {
  45                 fprintf(stderr, "error: mount tmpfs, errno %d\n", errno);
  46                 return 1;
  47         }
  48
  49         fd = openat(AT_FDCWD, "/tmp", O_WRONLY|O_TMPFILE, 0600);
  50         if (fd == -1) {
  51                 fprintf(stderr, "error: open 1, errno %d\n", errno);
  52                 return 1;
  53         }
  54         if (linkat(fd, "", AT_FDCWD, "/tmp/1", AT_EMPTY_PATH) == -1) {
  55                 fprintf(stderr, "error: linkat, errno %d\n", errno);
  56                 return 1;
  57         }
  58         close(fd);
  59
  60         fd = openat(AT_FDCWD, "/tmp", O_WRONLY|O_TMPFILE, 0600);
  61         if (fd == -1) {
  62                 fprintf(stderr, "error: open 2, errno %d\n", errno);
  63                 return 1;
  64         }
  65
  66         return 0;
  67 }