io/dup2.c

   1 /* Copyright (C) 1991-2023 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    <https://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.  Return FD2 or -1.  */
  25 int
  26 __dup2 (int fd, int fd2)
  27 {
  28   if (fd < 0 || fd2 < 0)
  29     {
  30       __set_errno (EBADF);
  31       return -1;
  32     }
  33
  34   if (fd == fd2)
  35     /* No way to check that they are valid.  */
  36     return fd2;
  37
  38   __set_errno (ENOSYS);
  39   return -1;
  40 }
  41 libc_hidden_def (__dup2)
  42 stub_warning (dup2)
  43
  44 weak_alias (__dup2, dup2)