sysdeps/unix/sysv/linux/generic/dup2.c

   1 /* Copyright (C) 2011-2016 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library 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 GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library.  If not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <fcntl.h>
  21 #include <limits.h>
  22 #include <unistd.h>
  23
  24 /* Duplicate FD to FD2, closing the old FD2 and making FD2 be
  25    open the same file as FD is.  Return FD2 or -1.  */
  26 int
  27 __dup2 (int fd, int fd2)
  28 {
  29   /* For the degenerate case, check if the fd is valid (by trying to
  30      get the file status flags) and return it, or else return EBADF.  */
  31   if (fd == fd2)
  32     return __libc_fcntl (fd, F_GETFL, 0) < 0 ? -1 : fd;
  33
  34   return INLINE_SYSCALL (dup3, 3, fd, fd2, 0);
  35 }
  36 libc_hidden_def (__dup2)
  37 weak_alias (__dup2, dup2)