lib/pipe-safer.c

   1 /* Invoke pipe, but avoid some glitches.
   2    Copyright (C) 2005-2006, 2009-2020 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 <https://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
  30 int
  31 pipe_safer (int fd[2])
  32 {
  33   if (pipe (fd) == 0)
  34     {
  35       int i;
  36       for (i = 0; i < 2; i++)
  37         {
  38           fd[i] = fd_safer (fd[i]);
  39           if (fd[i] < 0)
  40             {
  41               int saved_errno = errno;
  42               close (fd[1 - i]);
  43               errno = saved_errno;
  44               return -1;
  45             }
  46         }
  47
  48       return 0;
  49     }
  50
  51   return -1;
  52 }