tests/test-spawn-pipe-child.c

/* Child program invoked by test-spawn-pipe-main.
   Copyright (C) 2009-2016 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3, or (at your option)
   any later version.

   This program 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 General Public License for more details.

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

#include <config.h>

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
/* Get declarations of the native Windows API functions.  */
# define WIN32_LEAN_AND_MEAN
# include <windows.h>
#endif

/* Depending on arguments, this test intentionally closes stderr or
   starts life with stderr closed.  So, we arrange to have fd 10
   (outside the range of interesting fd's during the test) set up to
   duplicate the original stderr.  */

#define BACKUP_STDERR_FILENO 10
#define ASSERT_STREAM myerr
#include "macros.h"

static FILE *myerr;

/* In this file, we use only system functions, no overrides from gnulib.  */
#undef atoi
#undef close
#undef fcntl
#undef fdopen
#undef fflush
#undef fprintf
#undef read
#undef write

/* Return non-zero if FD is open.  */
static int
is_open (int fd)
{
#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  /* On native Windows, the initial state of unassigned standard file
     descriptors is that they are open but point to an
     INVALID_HANDLE_VALUE, and there is no fcntl.  */
  return (HANDLE) _get_osfhandle (fd) != INVALID_HANDLE_VALUE;
#else
# ifndef F_GETFL
#  error Please port fcntl to your platform
# endif
  return 0 <= fcntl (fd, F_GETFL);
#endif
}

int
main (int argc, char *argv[])
{
  char buffer[2] = { 's', 't' };
  int fd;

  /* fd 2 might be closed, but fd BACKUP_STDERR_FILENO is the original
     stderr.  */
  myerr = fdopen (BACKUP_STDERR_FILENO, "w");
  if (!myerr)
    return 2;

  ASSERT (argc == 2);

  /* Read one byte from fd 0, and write its value plus one to fd 1.
     fd 2 should be closed iff the argument is 1.  Check that no other file
     descriptors leaked.  */

  ASSERT (read (STDIN_FILENO, buffer, 2) == 1);

  buffer[0]++;
  ASSERT (write (STDOUT_FILENO, buffer, 1) == 1);

  switch (atoi (argv[1]))
    {
    case 0:
      /* Expect fd 2 is open.  */
      ASSERT (is_open (STDERR_FILENO));
      break;
    case 1:
      /* Expect fd 2 is closed.
         But on HP-UX 11, fd 2 gets automatically re-opened to /dev/null if it
         was closed. Future POSIX will allow this, see
         <http://austingroupbugs.net/view.php?id=173>.  */
#if !defined __hpux
      ASSERT (! is_open (STDERR_FILENO));
#endif
      break;
    default:
      ASSERT (0);
    }

  for (fd = 3; fd < 7; fd++)
    {
      errno = 0;
      ASSERT (close (fd) == -1);
      ASSERT (errno == EBADF);
    }

  return 0;
}