1/* Open a stream to a file.
2   Copyright (C) 2007-2010 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#include <config.h>
20
21/* Get the original definition of fopen.  It might be defined as a macro.  */
22#define __need_FILE
23#include <stdio.h>
24#undef __need_FILE
25
26static inline FILE *
27orig_fopen (const char *filename, const char *mode)
28{
29  return fopen (filename, mode);
30}
31
32/* Specification.  */
33#include <stdio.h>
34
35#include <errno.h>
36#include <fcntl.h>
37#include <string.h>
38#include <unistd.h>
39#include <sys/types.h>
40#include <sys/stat.h>
41
42FILE *
43rpl_fopen (const char *filename, const char *mode)
44{
45#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
46  if (strcmp (filename, "/dev/null") == 0)
47    filename = "NUL";
48#endif
49
50#if FOPEN_TRAILING_SLASH_BUG
51  /* If the filename ends in a slash and a mode that requires write access is
52     specified, then fail.
53     Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html>
54     says that
55       "A pathname that contains at least one non-slash character and that
56        ends with one or more trailing slashes shall be resolved as if a
57        single dot character ( '.' ) were appended to the pathname."
58     and
59       "The special filename dot shall refer to the directory specified by
60        its predecessor."
61     If the named file already exists as a directory, then if a mode that
62     requires write access is specified, fopen() must fail because POSIX
63     <http://www.opengroup.org/susv3/functions/fopen.html> says that it
64     fails with errno = EISDIR in this case.
65     If the named file does not exist or does not name a directory, then
66     fopen() must fail since the file does not contain a '.' directory.  */
67  {
68    size_t len = strlen (filename);
69    if (len > 0 && filename[len - 1] == '/')
70      {
71        int fd;
72        struct stat statbuf;
73        FILE *fp;
74
75        if (mode[0] == 'w' || mode[0] == 'a')
76          {
77            errno = EISDIR;
78            return NULL;
79          }
80
81        fd = open (filename, O_RDONLY);
82        if (fd < 0)
83          return NULL;
84
85        if (fstat (fd, &statbuf) >= 0 && !S_ISDIR (statbuf.st_mode))
86          {
87            close (fd);
88            errno = ENOTDIR;
89            return NULL;
90          }
91
92        fp = fdopen (fd, mode);
93        if (fp == NULL)
94          {
95            int saved_errno = errno;
96            close (fd);
97            errno = saved_errno;
98          }
99        return fp;
100      }
101  }
102# endif
103
104  return orig_fopen (filename, mode);
105}
106