tests/test-dirent-safer.c

   1 /* Test that directory streams leave standard fds alone.
   2    Copyright (C) 2009-2017 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 <http://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Eric Blake <ebb9@byu.net>, 2009.  */
  18
  19 #include <config.h>
  20
  21 #include "dirent--.h"
  22
  23 #include <errno.h>
  24 #include <fcntl.h>
  25 #include <stdio.h>
  26 #include <unistd.h>
  27
  28 #include "unistd-safer.h"
  29
  30 /* This test intentionally closes stderr.  So, we arrange to have fd 10
  31    (outside the range of interesting fd's during the test) set up to
  32    duplicate the original stderr.  */
  33
  34 #define BACKUP_STDERR_FILENO 10
  35 #define ASSERT_STREAM myerr
  36 #include "macros.h"
  37
  38 static FILE *myerr;
  39
  40 int
  41 main (void)
  42 {
  43   int i;
  44   DIR *dp;
  45   /* The dirent-safer module works without the use of fdopendir (which
  46      would also pull in fchdir and openat); but if those modules were
  47      also used, we ensure that they are safe.  In particular, the
  48      gnulib version of fdopendir is unable to guarantee that
  49      dirfd(fdopendir(fd))==fd, but we can at least guarantee that if
  50      they are not equal, the fd returned by dirfd is safe.  */
  51 #if HAVE_FDOPENDIR || GNULIB_TEST_FDOPENDIR
  52   int dfd;
  53 #endif
  54
  55   /* We close fd 2 later, so save it in fd 10.  */
  56   if (dup2 (STDERR_FILENO, BACKUP_STDERR_FILENO) != BACKUP_STDERR_FILENO
  57       || (myerr = fdopen (BACKUP_STDERR_FILENO, "w")) == NULL)
  58     return 2;
  59
  60 #if HAVE_FDOPENDIR || GNULIB_TEST_FDOPENDIR
  61   dfd = open (".", O_RDONLY);
  62   ASSERT (STDERR_FILENO < dfd);
  63 #endif
  64
  65   /* Four iterations, with progressively more standard descriptors
  66      closed.  */
  67   for (i = -1; i <= STDERR_FILENO; i++)
  68     {
  69       if (0 <= i)
  70         ASSERT (close (i) == 0);
  71       dp = opendir (".");
  72       ASSERT (dp);
  73       ASSERT (dirfd (dp) == -1 || STDERR_FILENO < dirfd (dp));
  74       ASSERT (closedir (dp) == 0);
  75
  76 #if HAVE_FDOPENDIR || GNULIB_TEST_FDOPENDIR
  77       {
  78         int fd = dup_safer (dfd);
  79         ASSERT (STDERR_FILENO < fd);
  80         dp = fdopendir (fd);
  81         ASSERT (dp);
  82         ASSERT (dirfd (dp) == -1 || STDERR_FILENO < dirfd (dp));
  83         ASSERT (closedir (dp) == 0);
  84         errno = 0;
  85         ASSERT (close (fd) == -1);
  86         ASSERT (errno == EBADF);
  87       }
  88 #endif
  89     }
  90
  91 #if HAVE_FDOPENDIR || GNULIB_TEST_FDOPENDIR
  92   ASSERT (close (dfd) == 0);
  93 #endif
  94
  95   return 0;
  96 }