io/dup3.c

   1 /* Copyright (C) 2008-2017 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <fcntl.h>
  20 #include <unistd.h>
  21
  22
  23 /* Duplicate FD to FD2, closing the old FD2 and making FD2 be
  24    open the same file as FD is which setting flags according to
  25    FLAGS.  Return FD2 or -1.  */
  26 int
  27 __dup3 (int fd, int fd2, int flags)
  28 {
  29   if (fd < 0 || fd2 < 0)
  30     {
  31       __set_errno (EBADF);
  32       return -1;
  33     }
  34
  35   if (fd == fd2)
  36     /* No way to check that they are valid.  */
  37     return fd2;
  38
  39   __set_errno (ENOSYS);
  40   return -1;
  41 }
  42 libc_hidden_def (__dup3)
  43 weak_alias (__dup3, dup3)
  44 stub_warning (dup3)