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| 1 /* Return a safer copy of a file descriptor. |
| 2 |
| 3 Copyright (C) 2005, 2006 Free Software Foundation, Inc. |
| 4 |
| 5 This program is free software: you can redistribute it and/or modify |
| 6 it under the terms of the GNU General Public License as published by |
| 7 the Free Software Foundation; either version 3 of the License, or |
| 8 (at your option) any later version. |
| 9 |
| 10 This program 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 |
| 13 GNU General Public License for more details. |
| 14 |
| 15 You should have received a copy of the GNU General Public License |
| 16 along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 17 |
| 18 /* Written by Paul Eggert. */ |
| 19 |
| 20 #include <config.h> |
| 21 |
| 22 #include "unistd-safer.h" |
| 23 |
| 24 #include <errno.h> |
| 25 |
| 26 #include <unistd.h> |
| 27 #ifndef STDIN_FILENO |
| 28 # define STDIN_FILENO 0 |
| 29 #endif |
| 30 #ifndef STDERR_FILENO |
| 31 # define STDERR_FILENO 2 |
| 32 #endif |
| 33 |
| 34 /* Return FD, unless FD would be a copy of standard input, output, or |
| 35 error; in that case, return a duplicate of FD, closing FD. On |
| 36 failure to duplicate, close FD, set errno, and return -1. Preserve |
| 37 errno if FD is negative, so that the caller can always inspect |
| 38 errno when the returned value is negative. |
| 39 |
| 40 This function is usefully wrapped around functions that return file |
| 41 descriptors, e.g., fd_safer (open ("file", O_RDONLY)). */ |
| 42 |
| 43 int |
| 44 fd_safer (int fd) |
| 45 { |
| 46 if (STDIN_FILENO <= fd && fd <= STDERR_FILENO) |
| 47 { |
| 48 int f = dup_safer (fd); |
| 49 int e = errno; |
| 50 close (fd); |
| 51 errno = e; |
| 52 fd = f; |
| 53 } |
| 54 |
| 55 return fd; |
| 56 } |
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