/* Create a pipe, with specific opening flags.
   Copyright (C) 2009 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 2, 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, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

#include <config.h>

/* Specification.  */
#include <unistd.h>

#include <errno.h>
#include <fcntl.h>

#include "binary-io.h"

#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
/* Native Woe32 API.  */

# include <io.h>

#else
/* Unix API.  */

# ifndef O_CLOEXEC
#  define O_CLOEXEC 0
# endif

#endif

int
pipe2 (int fd[2], int flags)
{
#if HAVE_PIPE2
# undef pipe2
  /* Try the system call first, if it exists.  (We may be running with a glibc
     that has the function but with an older kernel that lacks it.)  */
  {
    /* Cache the information whether the system call really exists.  */
    static int have_pipe2_really; /* 0 = unknown, 1 = yes, -1 = no */
    if (have_pipe2_really >= 0)
      {
	int result = pipe2 (fd, flags);
	if (!(result < 0 && errno == ENOSYS))
	  {
	    have_pipe2_really = 1;
	    return result;
	  }
	have_pipe2_really = -1;
      }
  }
#endif

#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
/* Native Woe32 API.  */

  /* Check the supported flags.  */
  if ((flags & ~(O_CLOEXEC | O_BINARY | O_TEXT)) != 0)
    {
      errno = EINVAL;
      return -1;
    }

  return _pipe (fd, 4096, flags);

#else
/* Unix API.  */

  /* Check the supported flags.  */
  if ((flags & ~(O_CLOEXEC | O_NONBLOCK | O_TEXT | O_BINARY)) != 0)
    {
      errno = EINVAL;
      return -1;
    }

  if (pipe (fd) < 0)
    return -1;

  /* POSIX <http://www.opengroup.org/onlinepubs/9699919799/functions/pipe.html>
     says that initially, the O_NONBLOCK and FD_CLOEXEC flags are cleared on
     both fd[0] amd fd[1].  */

  if (flags & O_NONBLOCK)
    {
      int fcntl_flags;

      if ((fcntl_flags = fcntl (fd[1], F_GETFL, 0)) < 0
	  || fcntl (fd[1], F_SETFL, fcntl_flags | O_NONBLOCK) == -1
	  || (fcntl_flags = fcntl (fd[0], F_GETFL, 0)) < 0
	  || fcntl (fd[0], F_SETFL, fcntl_flags | O_NONBLOCK) == -1)
	goto fail;
    }

  if (flags & O_CLOEXEC)
    {
      int fcntl_flags;

      if ((fcntl_flags = fcntl (fd[1], F_GETFD, 0)) < 0
	  || fcntl (fd[1], F_SETFD, fcntl_flags | FD_CLOEXEC) == -1
	  || (fcntl_flags = fcntl (fd[0], F_GETFD, 0)) < 0
	  || fcntl (fd[0], F_SETFD, fcntl_flags | FD_CLOEXEC) == -1)
	goto fail;
    }

# if O_BINARY
  if (flags & O_BINARY)
    {
      setmode (fd[1], O_BINARY);
      setmode (fd[0], O_BINARY);
    }
  else if (flags & O_TEXT)
    {
      setmode (fd[1], O_TEXT);
      setmode (fd[0], O_TEXT);
    }
# endif

  return 0;

 fail:
  {
    int saved_errno = errno;
    close (fd[0]);
    close (fd[1]);
    errno = saved_errno;
    return -1;
  }

#endif
}
