1  /* Invoke pipe, but avoid some glitches.
       2     Copyright (C) 2005-2006, 2009-2023 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  }