1 /* Copyright (C) 2011-2022 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 <fcntl.h>
19 #include <unistd.h>
20 #include <sysdep.h>
21
22 /* Duplicate FD to FD2, closing the old FD2 and making FD2 be
23 open the same file as FD is. Return FD2 or -1. */
24 int
__dup2(int fd,int fd2)25 __dup2 (int fd, int fd2)
26 {
27 /* For the degenerate case, check if the fd is valid (by trying to
28 get the file status flags) and return it, or else return EBADF. */
29 if (fd == fd2)
30 return __libc_fcntl (fd, F_GETFL, 0) < 0 ? -1 : fd;
31
32 return INLINE_SYSCALL (dup3, 3, fd, fd2, 0);
33 }
34 libc_hidden_def (__dup2)
35 weak_alias (__dup2, dup2)
36