libio/tst-freopen.c

   1 /* Test freopen with mmap stdio.
   2    Copyright (C) 2002-2022 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <unistd.h>
  23
  24 #include <support/check.h>
  25 #include <support/temp_file.h>
  26
  27 static int fd;
  28 static char *name;
  29
  30 static void
  31 do_prepare (int argc, char *argv[])
  32 {
  33   fd = create_temp_file ("tst-freopen.", &name);
  34   TEST_VERIFY_EXIT (fd != -1);
  35 }
  36
  37 #define PREPARE do_prepare
  38
  39 /* Basic tests for freopen.  */
  40 static void
  41 do_test_basic (void)
  42 {
  43   const char * const test = "Let's test freopen.\n";
  44   char temp[strlen (test) + 1];
  45
  46   FILE *f = fdopen (fd, "w");
  47   if (f == NULL)
  48     FAIL_EXIT1 ("fdopen: %m");
  49
  50   fputs (test, f);
  51   fclose (f);
  52
  53   f = fopen (name, "r");
  54   if (f == NULL)
  55     FAIL_EXIT1 ("fopen: %m");
  56
  57   if (fread (temp, 1, strlen (test), f) != strlen (test))
  58     FAIL_EXIT1 ("fread: %m");
  59   temp [strlen (test)] = '\0';
  60
  61   if (strcmp (test, temp))
  62     FAIL_EXIT1 ("read different string than was written: (%s, %s)",
  63                 test, temp);
  64
  65   f = freopen (name, "r+", f);
  66   if (f == NULL)
  67     FAIL_EXIT1 ("freopen: %m");
  68
  69   if (fseek (f, 0, SEEK_SET) != 0)
  70     FAIL_EXIT1 ("fseek: %m");
  71
  72   if (fread (temp, 1, strlen (test), f) != strlen (test))
  73     FAIL_EXIT1 ("fread: %m");
  74   temp [strlen (test)] = '\0';
  75
  76   if (strcmp (test, temp))
  77     FAIL_EXIT1 ("read different string than was written: (%s, %s)",
  78                 test, temp);
  79
  80   fclose (f);
  81 }
  82
  83 #if defined __GNUC__ && __GNUC__ >= 11
  84 /* Force an error to detect incorrectly making freopen a deallocator
  85    for its last argument via attribute malloc.  The function closes
  86    the stream without deallocating it so either the argument or
  87    the pointer returned from the function (but not both) can be passed
  88    to fclose.  */
  89 #pragma GCC diagnostic push
  90 #pragma GCC diagnostic error "-Wmismatched-dealloc"
  91 #endif
  92
  93 /* Verify that freopen returns stream.  */
  94 static void
  95 do_test_return_stream (void)
  96 {
  97   FILE *f1 = fopen (name, "r");
  98   if (f1 == NULL)
  99     FAIL_EXIT1 ("fopen: %m");
 100
 101   FILE *f2 = freopen (name, "r+", f1);
 102   if (f2 == NULL)
 103     FAIL_EXIT1 ("freopen: %m");
 104
 105   /* Verify that freopen isn't declared with the no-argument attribute
 106      malloc (which could let GCC fold the inequality to false).  */
 107   if (f1 != f2)
 108     FAIL_EXIT1 ("freopen returned a different stream");
 109
 110   /* This shouldn't trigger -Wmismatched-dealloc.  */
 111   fclose (f1);
 112 }
 113
 114 #if defined __GNUC__ && __GNUC__ >= 11
 115 /* Pop -Wmismatched-dealloc set to error above.  */
 116 # pragma GCC diagnostic pop
 117 #endif
 118
 119 /* Test for BZ#21398, where it tries to freopen stdio after the close
 120    of its file descriptor.  */
 121 static void
 122 do_test_bz21398 (void)
 123 {
 124   (void) close (STDIN_FILENO);
 125
 126   FILE *f = freopen (name, "r", stdin);
 127   if (f == NULL)
 128     FAIL_EXIT1 ("freopen: %m");
 129
 130   TEST_VERIFY_EXIT (ferror (f) == 0);
 131
 132   char buf[128];
 133   char *ret = fgets (buf, sizeof (buf), stdin);
 134   TEST_VERIFY_EXIT (ret != NULL);
 135   TEST_VERIFY_EXIT (ferror (f) == 0);
 136 }
 137
 138 static int
 139 do_test (void)
 140 {
 141   do_test_basic ();
 142   do_test_bz21398 ();
 143   do_test_return_stream ();
 144
 145   return 0;
 146 }
 147
 148 #include <support/test-driver.c>