| 1 | /* Copyright (C) 1991-2024 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 <limits.h> |
| 21 | #include <unistd.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. */ |
| 25 | int |
| 26 | __dup2 (int fd, int fd2) |
| 27 | { |
| 28 | int save; |
| 29 | |
| 30 | if (fd2 < 0 |
| 31 | #ifdef OPEN_MAX |
| 32 | || fd2 >= OPEN_MAX |
| 33 | #endif |
| 34 | ) |
| 35 | { |
| 36 | __set_errno (EBADF); |
| 37 | return -1; |
| 38 | } |
| 39 | |
| 40 | /* Check if FD is kosher. */ |
| 41 | if (fcntl (fd: fd, F_GETFL) < 0) |
| 42 | return -1; |
| 43 | |
| 44 | if (fd == fd2) |
| 45 | return fd2; |
| 46 | |
| 47 | /* This is not atomic. */ |
| 48 | |
| 49 | save = errno; |
| 50 | (void) close (fd: fd2); |
| 51 | __set_errno (save); |
| 52 | |
| 53 | return fcntl (fd: fd, F_DUPFD, fd2); |
| 54 | } |
| 55 | libc_hidden_def (__dup2) |
| 56 | weak_alias (__dup2, dup2) |
| 57 |