tests/test-freopen-safer.c

   1 /* Test of reopening a stream.
   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 /* Specification.  */
  22 #include "stdio--.h"
  23
  24 /* Helpers.  */
  25 #include <unistd.h>
  26
  27 /* This test intentionally closes stderr.  So, we arrange to have fd 10
  28    (outside the range of interesting fd's during the test) set up to
  29    duplicate the original stderr.  */
  30
  31 #define BACKUP_STDERR_FILENO 10
  32 #define ASSERT_STREAM myerr
  33 #include "macros.h"
  34
  35 static FILE *myerr;
  36
  37 int
  38 main (void)
  39 {
  40   FILE *fp;
  41
  42   /* We close fd 2 later, so save it in fd 10.  */
  43   if (dup2 (STDERR_FILENO, BACKUP_STDERR_FILENO) != BACKUP_STDERR_FILENO
  44       || (myerr = fdopen (BACKUP_STDERR_FILENO, "w")) == NULL)
  45     return 2;
  46
  47   {
  48     FILE *tmp;
  49     ASSERT (tmp = fopen ("/dev/null", "r"));
  50     ASSERT (STDERR_FILENO < fileno (tmp));
  51     ASSERT (fp = fopen ("/dev/null", "w"));
  52     ASSERT (fileno (tmp) < fileno (fp));
  53     ASSERT (fclose (tmp) == 0);
  54   }
  55
  56   /* Gap in fds.  */
  57   ASSERT (freopen ("/dev/null", "r+", fp) == fp);
  58   ASSERT (STDERR_FILENO < fileno (fp));
  59
  60   ASSERT (freopen ("/dev/null", "r", stdin) == stdin);
  61   ASSERT (STDIN_FILENO == fileno (stdin));
  62
  63   ASSERT (freopen ("/dev/null", "w", stdout) == stdout);
  64   ASSERT (STDOUT_FILENO == fileno (stdout));
  65
  66   ASSERT (freopen ("/dev/null", "w", stderr) == stderr);
  67   ASSERT (STDERR_FILENO == fileno (stderr));
  68
  69   /* fd 0 closed.  */
  70   ASSERT (close (STDIN_FILENO) == 0);
  71
  72   ASSERT (freopen ("/dev/null", "w", stdout) == stdout);
  73   ASSERT (STDOUT_FILENO == fileno (stdout));
  74
  75   ASSERT (freopen ("/dev/null", "w", stderr) == stderr);
  76   ASSERT (STDERR_FILENO == fileno (stderr));
  77
  78   ASSERT (freopen ("/dev/null", "a", fp) == fp);
  79   ASSERT (STDERR_FILENO < fileno (fp));
  80
  81   /* fd 1 closed.  */
  82   ASSERT (close (STDOUT_FILENO) == 0);
  83
  84   ASSERT (freopen ("/dev/null", "w", stderr) == stderr);
  85   ASSERT (STDERR_FILENO == fileno (stderr));
  86
  87   ASSERT (freopen ("/dev/null", "a+", fp) == fp);
  88   ASSERT (STDERR_FILENO < fileno (fp));
  89
  90   /* fd 2 closed.  */
  91   ASSERT (close (STDERR_FILENO) == 0);
  92
  93   ASSERT (freopen ("/dev/null", "w+", fp) == fp);
  94   ASSERT (STDERR_FILENO < fileno (fp));
  95
  96   return test_exit_status;
  97 }