1  /* Test that openat_safer leave standard fds alone.
       2     Copyright (C) 2009-2022 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 0;
     125  }