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

   1 /* Copyright (C) 2011 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <limits.h>
  23 #include <unistd.h>
  24
  25 /* Duplicate FD to FD2, closing the old FD2 and making FD2 be
  26    open the same file as FD is.  Return FD2 or -1.  */
  27 int
  28 __dup2 (int fd, int fd2)
  29 {
  30   /* For the degenerate case, check if the fd is valid (by trying to
  31      get the file status flags) and return it, or else return EBADF.  */
  32   if (fd == fd2)
  33     return __libc_fcntl (fd, F_GETFL, 0) < 0 ? -1 : fd;
  34
  35   return INLINE_SYSCALL (dup3, 3, fd, fd2, 0);
  36 }
  37 libc_hidden_def (__dup2)
  38 weak_alias (__dup2, dup2)