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Member "gcal-4.1/lib/fd-safer.c" (22 Jan 2017, 1538 Bytes) of package /linux/misc/gcal-4.1.tar.gz:


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    1 /* Return a safer copy of a file descriptor.
    2 
    3    Copyright (C) 2005-2006, 2009-2017 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 #include <unistd.h>
   26 
   27 /* Return FD, unless FD would be a copy of standard input, output, or
   28    error; in that case, return a duplicate of FD, closing FD.  On
   29    failure to duplicate, close FD, set errno, and return -1.  Preserve
   30    errno if FD is negative, so that the caller can always inspect
   31    errno when the returned value is negative.
   32 
   33    This function is usefully wrapped around functions that return file
   34    descriptors, e.g., fd_safer (open ("file", O_RDONLY)).  */
   35 
   36 int
   37 fd_safer (int fd)
   38 {
   39   if (STDIN_FILENO <= fd && fd <= STDERR_FILENO)
   40     {
   41       int f = dup_safer (fd);
   42       int e = errno;
   43       close (fd);
   44       errno = e;
   45       fd = f;
   46     }
   47 
   48   return fd;
   49 }