glibc/libio/tst-freopen.c

/* Test freopen with mmap stdio.
   Copyright (C) 2002-2024 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <support/check.h>
#include <support/temp_file.h>

static int fd;
static char *name;

static void
do_prepare (int argc, char *argv[])
{
  fd = create_temp_file ("tst-freopen.", &name);
  TEST_VERIFY_EXIT (fd != -1);
}

#define PREPARE do_prepare

/* Basic tests for freopen.  */
static void
do_test_basic (void)
{
  const char * const test = "Let's test freopen.\n";
  char temp[strlen (test) + 1];

  FILE *f = fdopen (fd, "w");
  if (f == NULL)
    FAIL_EXIT1 ("fdopen: %m");

  fputs (test, f);
  fclose (f);

  f = fopen (name, "r");
  if (f == NULL)
    FAIL_EXIT1 ("fopen: %m");

  if (fread (temp, 1, strlen (test), f) != strlen (test))
    FAIL_EXIT1 ("fread: %m");
  temp [strlen (test)] = '\0';

  if (strcmp (test, temp))
    FAIL_EXIT1 ("read different string than was written: (%s, %s)",
	        test, temp);

  f = freopen (name, "r+", f);
  if (f == NULL)
    FAIL_EXIT1 ("freopen: %m");

  if (fseek (f, 0, SEEK_SET) != 0)
    FAIL_EXIT1 ("fseek: %m");

  if (fread (temp, 1, strlen (test), f) != strlen (test))
    FAIL_EXIT1 ("fread: %m");
  temp [strlen (test)] = '\0';

  if (strcmp (test, temp))
    FAIL_EXIT1 ("read different string than was written: (%s, %s)",
	        test, temp);

  fclose (f);
}

#if defined __GNUC__ && __GNUC__ >= 11
/* Force an error to detect incorrectly making freopen a deallocator
   for its last argument via attribute malloc.  The function closes
   the stream without deallocating it so either the argument or
   the pointer returned from the function (but not both) can be passed
   to fclose.  */
#pragma GCC diagnostic push
#pragma GCC diagnostic error "-Wmismatched-dealloc"
#endif

/* Verify that freopen returns stream.  */
static void
do_test_return_stream (void)
{
  FILE *f1 = fopen (name, "r");
  if (f1 == NULL)
    FAIL_EXIT1 ("fopen: %m");

  FILE *f2 = freopen (name, "r+", f1);
  if (f2 == NULL)
    FAIL_EXIT1 ("freopen: %m");

  /* Verify that freopen isn't declared with the no-argument attribute
     malloc (which could let GCC fold the inequality to false).  */
  if (f1 != f2)
    FAIL_EXIT1 ("freopen returned a different stream");

  /* This shouldn't trigger -Wmismatched-dealloc.  */
  fclose (f1);
}

#if defined __GNUC__ && __GNUC__ >= 11
/* Pop -Wmismatched-dealloc set to error above.  */
# pragma GCC diagnostic pop
#endif

/* Test for BZ#21398, where it tries to freopen stdio after the close
   of its file descriptor.  */
static void
do_test_bz21398 (void)
{
  (void) close (STDIN_FILENO);

  FILE *f = freopen (name, "r", stdin);
  if (f == NULL)
    FAIL_EXIT1 ("freopen: %m");

  TEST_VERIFY_EXIT (ferror (f) == 0);

  char buf[128];
  char *ret = fgets (buf, sizeof (buf), stdin);
  TEST_VERIFY_EXIT (ret != NULL);
  TEST_VERIFY_EXIT (ferror (f) == 0);
}

static int
do_test (void)
{
  do_test_basic ();
  do_test_bz21398 ();
  do_test_return_stream ();

  return 0;
}

#include <support/test-driver.c>