1 /* Invoke fopen, but avoid some glitches.
2 Copyright (C) 2001, 2004, 2005 Free Software Foundation, Inc.
3
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2, or (at your option)
7 any later version.
8
9 This program 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
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software Foundation,
16 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
17
18 /* Written by Paul Eggert. */
19
20 #ifdef HAVE_CONFIG_H
21 # include <config.h>
22 #endif
23
24 #include "stdio-safer.h"
25
26 #include <errno.h>
27 #include <unistd.h>
28 #include "unistd-safer.h"
29
30 #ifndef STDERR_FILENO
31 # define STDERR_FILENO 2
32 #endif
33
34 /* Like fopen, but do not return stdin, stdout, or stderr. */
35
36 FILE *
fopen_safer(char const * file,char const * mode)37 fopen_safer (char const *file, char const *mode)
38 {
39 FILE *fp = fopen (file, mode);
40
41 if (fp)
42 {
43 int fd = fileno (fp);
44
45 if (0 <= fd && fd <= STDERR_FILENO)
46 {
47 int f = dup_safer (fd);
48
49 if (f < 0)
50 {
51 int e = errno;
52 fclose (fp);
53 errno = e;
54 return NULL;
55 }
56
57 if (fclose (fp) != 0
58 || ! (fp = fdopen (f, mode)))
59 {
60 int e = errno;
61 close (f);
62 errno = e;
63 return NULL;
64 }
65 }
66 }
67
68 return fp;
69 }
70