1/* Open a stream to a file.
2   Copyright (C) 2007-2012 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 3 of the License, or
7   (at your option) 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, see <http://www.gnu.org/licenses/>.  */
16
17/* Written by Bruno Haible <bruno@clisp.org>, 2007.  */
18
19/* If the user's config.h happens to include <stdio.h>, let it include only
20   the system's <stdio.h> here, so that orig_fopen doesn't recurse to
21   rpl_fopen.  */
22#define __need_FILE
23#include <config.h>
24
25/* Get the original definition of fopen.  It might be defined as a macro.  */
26#include <stdio.h>
27#undef __need_FILE
28
29static FILE *
30orig_fopen (const char *filename, const char *mode)
31{
32  return fopen (filename, mode);
33}
34
35/* Specification.  */
36/* Write "stdio.h" here, not <stdio.h>, otherwise OSF/1 5.1 DTK cc eliminates
37   this include because of the preliminary #include <stdio.h> above.  */
38#include "stdio.h"
39
40#include <errno.h>
41#include <fcntl.h>
42#include <string.h>
43#include <unistd.h>
44#include <sys/types.h>
45#include <sys/stat.h>
46
47FILE *
48rpl_fopen (const char *filename, const char *mode)
49{
50#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
51  if (strcmp (filename, "/dev/null") == 0)
52    filename = "NUL";
53#endif
54
55#if FOPEN_TRAILING_SLASH_BUG
56  /* If the filename ends in a slash and a mode that requires write access is
57     specified, then fail.
58     Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html>
59     says that
60       "A pathname that contains at least one non-slash character and that
61        ends with one or more trailing slashes shall be resolved as if a
62        single dot character ( '.' ) were appended to the pathname."
63     and
64       "The special filename dot shall refer to the directory specified by
65        its predecessor."
66     If the named file already exists as a directory, then if a mode that
67     requires write access is specified, fopen() must fail because POSIX
68     <http://www.opengroup.org/susv3/functions/fopen.html> says that it
69     fails with errno = EISDIR in this case.
70     If the named file does not exist or does not name a directory, then
71     fopen() must fail since the file does not contain a '.' directory.  */
72  {
73    size_t len = strlen (filename);
74    if (len > 0 && filename[len - 1] == '/')
75      {
76        int fd;
77        struct stat statbuf;
78        FILE *fp;
79
80        if (mode[0] == 'w' || mode[0] == 'a')
81          {
82            errno = EISDIR;
83            return NULL;
84          }
85
86        fd = open (filename, O_RDONLY);
87        if (fd < 0)
88          return NULL;
89
90        if (fstat (fd, &statbuf) >= 0 && !S_ISDIR (statbuf.st_mode))
91          {
92            close (fd);
93            errno = ENOTDIR;
94            return NULL;
95          }
96
97        fp = fdopen (fd, mode);
98        if (fp == NULL)
99          {
100            int saved_errno = errno;
101            close (fd);
102            errno = saved_errno;
103          }
104        return fp;
105      }
106  }
107# endif
108
109  return orig_fopen (filename, mode);
110}
111