Line data    Source code

       1             : /* Return a safer copy of a file descriptor.
       2             : 
       3             :    Copyright (C) 2005, 2006 Free Software Foundation, Inc.
       4             : 
       5             :    This program is free software: you can redistribute it and/or modify
       6             :    it under the terms of the GNU General Public License as published by
       7             :    the Free Software Foundation; either version 3 of the License, or
       8             :    (at your option) any later version.
       9             : 
      10             :    This program is distributed in the hope that it will be useful,
      11             :    but WITHOUT ANY WARRANTY; without even the implied warranty of
      12             :    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      13             :    GNU General Public License for more details.
      14             : 
      15             :    You should have received a copy of the GNU General Public License
      16             :    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
      17             : 
      18             : /* Written by Paul Eggert.  */
      19             : 
      20             : #include <config.h>
      21             : 
      22             : #include "unistd-safer.h"
      23             : 
      24             : #include <errno.h>
      25             : 
      26             : #include <unistd.h>
      27             : #ifndef STDIN_FILENO
      28             : # define STDIN_FILENO 0
      29             : #endif
      30             : #ifndef STDERR_FILENO
      31             : # define STDERR_FILENO 2
      32             : #endif
      33             : 
      34             : /* Return FD, unless FD would be a copy of standard input, output, or
      35             :    error; in that case, return a duplicate of FD, closing FD.  On
      36             :    failure to duplicate, close FD, set errno, and return -1.  Preserve
      37             :    errno if FD is negative, so that the caller can always inspect
      38             :    errno when the returned value is negative.
      39             : 
      40             :    This function is usefully wrapped around functions that return file
      41             :    descriptors, e.g., fd_safer (open ("file", O_RDONLY)).  */
      42             : 
      43             : int
      44      135695 : fd_safer (int fd)
      45             : {
      46      135695 :   if (STDIN_FILENO <= fd && fd <= STDERR_FILENO)
      47             :     {
      48           0 :       int f = dup_safer (fd);
      49           0 :       int e = errno;
      50           0 :       close (fd);
      51           0 :       errno = e;
      52           0 :       fd = f;
      53             :     }
      54             : 
      55      135695 :   return fd;
      56             : }