1 /* Return a safer copy of a file descriptor.
3 Copyright (C) 2005, 2006 Free Software Foundation, Inc.
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 2, or (at your option)
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.
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software Foundation,
17 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
19 /* Written by Paul Eggert. */
23 #include "unistd-safer.h"
29 # define STDIN_FILENO 0
32 # define STDERR_FILENO 2
35 /* Return FD, unless FD would be a copy of standard input, output, or
36 error; in that case, return a duplicate of FD, closing FD. On
37 failure to duplicate, close FD, set errno, and return -1. Preserve
38 errno if FD is negative, so that the caller can always inspect
39 errno when the returned value is negative.
41 This function is usefully wrapped around functions that return file
42 descriptors, e.g., fd_safer (open ("file", O_RDONLY)). */
47 if (STDIN_FILENO <= fd && fd <= STDERR_FILENO)
49 int f = dup_safer (fd);