LXR linux/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
  26int 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}
  68