1/* Invoke pipe, but avoid some glitches.
2   Copyright (C) 2005, 2006 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 2, or (at your option)
7   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, write to the Free Software Foundation,
16   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
17
18/* Written by Jim Meyering.  */
19
20#include <config.h>
21
22#include "unistd-safer.h"
23
24#include <unistd.h>
25#include <errno.h>
26
27/* Like pipe, but ensure that neither of the file descriptors is
28   STDIN_FILENO, STDOUT_FILENO, or STDERR_FILENO.  Fail with ENOSYS on
29   platforms that lack pipe.  */
30
31int
32pipe_safer (int fd[2])
33{
34#if HAVE_PIPE
35  if (pipe (fd) == 0)
36    {
37      int i;
38      for (i = 0; i < 2; i++)
39	{
40	  fd[i] = fd_safer (fd[i]);
41	  if (fd[i] < 0)
42	    {
43	      int e = errno;
44	      close (fd[1 - i]);
45	      errno = e;
46	      return -1;
47	    }
48	}
49
50      return 0;
51    }
52#else
53  errno = ENOSYS;
54#endif
55
56  return -1;
57}
58