tests/test-openat-safer.c

   1 /* Test that openat_safer leave standard fds alone.
   2    Copyright (C) 2009-2024 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Eric Blake <ebb9@byu.net>, 2009.  */
  18
  19 #include <config.h>
  20
  21 #include "fcntl--.h"
  22
  23 #include <errno.h>
  24 #include <stdio.h>
  25 #include <sys/stat.h>
  26 #include <unistd.h>
  27
  28 /* This test intentionally closes stderr.  So, we arrange to have fd 10
  29    (outside the range of interesting fd's during the test) set up to
  30    duplicate the original stderr.  */
  31
  32 #define BACKUP_STDERR_FILENO 10
  33 #define ASSERT_STREAM myerr
  34 #include "macros.h"
  35
  36 static FILE *myerr;
  37
  38 #define witness "test-openat-safer.txt"
  39
  40 int
  41 main (void)
  42 {
  43   int i;
  44   int j;
  45   int dfd;
  46   int fd;
  47   char buf[2];
  48
  49   /* We close fd 2 later, so save it in fd 10.  */
  50   if (dup2 (STDERR_FILENO, BACKUP_STDERR_FILENO) != BACKUP_STDERR_FILENO
  51       || (myerr = fdopen (BACKUP_STDERR_FILENO, "w")) == NULL)
  52     return 2;
  53
  54   /* Create handle for future use.  */
  55   dfd = openat (AT_FDCWD, ".", O_RDONLY);
  56   ASSERT (STDERR_FILENO < dfd);
  57
  58   /* Create file for later checks.  */
  59   remove (witness);
  60   fd = openat (dfd, witness, O_WRONLY | O_CREAT | O_EXCL, 0600);
  61   ASSERT (STDERR_FILENO < fd);
  62   ASSERT (write (fd, "hi", 2) == 2);
  63   ASSERT (close (fd) == 0);
  64
  65   /* Four iterations, with progressively more standard descriptors
  66      closed.  */
  67   for (i = -1; i <= STDERR_FILENO; i++)
  68     {
  69       ASSERT (fchdir (dfd) == 0);
  70       if (0 <= i)
  71         ASSERT (close (i) == 0);
  72
  73       /* Execute once in ".", once in "..".  */
  74       for (j = 0; j <= 1; j++)
  75         {
  76           if (j)
  77             ASSERT (chdir ("..") == 0);
  78
  79           /* Check for error detection.  */
  80           errno = 0;
  81           ASSERT (openat (AT_FDCWD, "", O_RDONLY) == -1);
  82           ASSERT (errno == ENOENT);
  83           errno = 0;
  84           ASSERT (openat (dfd, "", O_RDONLY) == -1);
  85           ASSERT (errno == ENOENT);
  86           errno = 0;
  87           ASSERT (openat (-1, ".", O_RDONLY) == -1);
  88           ASSERT (errno == EBADF);
  89
  90           /* Check for trailing slash and /dev/null handling.  */
  91           errno = 0;
  92           ASSERT (openat (dfd, "nonexist.ent/", O_CREAT | O_RDONLY,
  93                           S_IRUSR | S_IWUSR) == -1);
  94           ASSERT (errno == ENOTDIR || errno == EISDIR || errno == ENOENT
  95                   || errno == EINVAL);
  96           errno = 0;
  97           ASSERT (openat (dfd, witness "/", O_RDONLY) == -1);
  98           ASSERT (errno == ENOTDIR || errno == EISDIR || errno == EINVAL);
  99 #if defined __linux__ || defined __ANDROID__
 100           /* Using a bad directory is okay for absolute paths.  */
 101           fd = openat (-1, "/dev/null", O_WRONLY);
 102           ASSERT (STDERR_FILENO < fd);
 103 #endif
 104           /* Using a non-directory is wrong for relative paths.  */
 105           errno = 0;
 106           fd = open ("/dev/null", O_RDONLY);
 107           ASSERT (STDERR_FILENO < fd);
 108           ASSERT (openat (fd, ".", O_RDONLY) == -1);
 109           ASSERT (errno == EBADF || errno == ENOTDIR);
 110           ASSERT (close (fd) == 0);
 111
 112           /* Check for our witness file.  */
 113           fd = openat (dfd, witness, O_RDONLY | O_NOFOLLOW);
 114           ASSERT (STDERR_FILENO < fd);
 115           ASSERT (read (fd, buf, 2) == 2);
 116           ASSERT (buf[0] == 'h' && buf[1] == 'i');
 117           ASSERT (close (fd) == 0);
 118         }
 119     }
 120   ASSERT (fchdir (dfd) == 0);
 121   ASSERT (unlink (witness) == 0);
 122   ASSERT (close (dfd) == 0);
 123
 124   return test_exit_status;
 125 }