1/* Invoke pipe, but avoid some glitches.
2   Copyright (C) 2005-2006, 2009-2012 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 3 of the License, or
7   (at your option) 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, see <http://www.gnu.org/licenses/>.  */
16
17/* Written by Jim Meyering.  */
18
19#include <config.h>
20
21#include "unistd-safer.h"
22
23#include <unistd.h>
24#include <errno.h>
25
26/* Like pipe, but ensure that neither of the file descriptors is
27   STDIN_FILENO, STDOUT_FILENO, or STDERR_FILENO.  Fail with ENOSYS on
28   platforms that lack pipe.  */
29
30int
31pipe_safer (int fd[2])
32{
33#if HAVE_PIPE
34  if (pipe (fd) == 0)
35    {
36      int i;
37      for (i = 0; i < 2; i++)
38        {
39          fd[i] = fd_safer (fd[i]);
40          if (fd[i] < 0)
41            {
42              int e = errno;
43              close (fd[1 - i]);
44              errno = e;
45              return -1;
46            }
47        }
48
49      return 0;
50    }
51#else
52  errno = ENOSYS;
53#endif
54
55  return -1;
56}
57