lib/dup-safer-flag.c

   1 /* Duplicate a file descriptor result, avoiding clobbering
   2    STD{IN,OUT,ERR}_FILENO, with specific flags.
   3
   4    Copyright (C) 2001, 2004-2006, 2009-2018 Free Software Foundation, Inc.
   5
   6    This program is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  18
  19 /* Written by Paul Eggert and Eric Blake.  */
  20
  21 #include <config.h>
  22
  23 /* Specification.  */
  24 #include "unistd-safer.h"
  25
  26 #include <fcntl.h>
  27 #include <unistd.h>
  28
  29 /* Like dup, but do not return STDIN_FILENO, STDOUT_FILENO, or
  30    STDERR_FILENO.  If FLAG contains O_CLOEXEC, behave like
  31    fcntl(F_DUPFD_CLOEXEC) rather than fcntl(F_DUPFD).  */
  32
  33 int
  34 dup_safer_flag (int fd, int flag)
  35 {
  36   return fcntl (fd, (flag & O_CLOEXEC) ? F_DUPFD_CLOEXEC : F_DUPFD,
  37                 STDERR_FILENO + 1);
  38 }