1/* Duplicate a file descriptor. Linux version.
2 Copyright (C) 2011-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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 <https://www.gnu.org/licenses/>. */
18
19#include <fcntl.h>
20#include <unistd.h>
21#include <sysdep.h>
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. */
25int
26__dup2 (int fd, int fd2)
27{
28#ifdef __NR_dup2
29 return INLINE_SYSCALL_CALL (dup2, fd, fd2);
30#else
31 /* For the degenerate case, check if the fd is valid (by trying to
32 get the file status flags) and return it, or else return EBADF. */
33 if (fd == fd2)
34 return __libc_fcntl (fd, F_GETFL, 0) < 0 ? -1 : fd;
35
36 return INLINE_SYSCALL_CALL (dup3, fd, fd2, 0);
37#endif
38}
39libc_hidden_def (__dup2)
40weak_alias (__dup2, dup2)
41