1 /* Open a descriptor to a file.
2 Copyright (C) 2007-2011 Free Software Foundation, Inc.
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.
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.
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/>. */
17 /* Written by Bruno Haible <bruno@clisp.org>, 2007. */
21 /* Get the original definition of open. It might be defined as a macro. */
22 #define __need_system_fcntl_h
24 #undef __need_system_fcntl_h
25 #include <sys/types.h>
28 orig_open (const char *filename, int flags, mode_t mode)
30 return open (filename, flags, mode);
39 #include <sys/types.h>
43 #ifndef REPLACE_OPEN_DIRECTORY
44 # define REPLACE_OPEN_DIRECTORY 0
48 open (const char *filename, int flags, ...)
57 va_start (arg, flags);
59 /* We have to use PROMOTED_MODE_T instead of mode_t, otherwise GCC 4
60 creates crashing code when 'mode_t' is smaller than 'int'. */
61 mode = va_arg (arg, PROMOTED_MODE_T);
66 #if GNULIB_defined_O_NONBLOCK
67 /* The only known platform that lacks O_NONBLOCK is mingw, but it
68 also lacks named pipes and Unix sockets, which are the only two
69 file types that require non-blocking handling in open().
70 Therefore, it is safe to ignore O_NONBLOCK here. It is handy
71 that mingw also lacks openat(), so that is also covered here. */
75 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
76 if (strcmp (filename, "/dev/null") == 0)
80 #if OPEN_TRAILING_SLASH_BUG
81 /* If the filename ends in a slash and one of O_CREAT, O_WRONLY, O_RDWR
82 is specified, then fail.
83 Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html>
85 "A pathname that contains at least one non-slash character and that
86 ends with one or more trailing slashes shall be resolved as if a
87 single dot character ( '.' ) were appended to the pathname."
89 "The special filename dot shall refer to the directory specified by
91 If the named file already exists as a directory, then
92 - if O_CREAT is specified, open() must fail because of the semantics
94 - if O_WRONLY or O_RDWR is specified, open() must fail because POSIX
95 <http://www.opengroup.org/susv3/functions/open.html> says that it
96 fails with errno = EISDIR in this case.
97 If the named file does not exist or does not name a directory, then
98 - if O_CREAT is specified, open() must fail since open() cannot create
100 - if O_WRONLY or O_RDWR is specified, open() must fail because the
101 file does not contain a '.' directory. */
102 if (flags & (O_CREAT | O_WRONLY | O_RDWR))
104 size_t len = strlen (filename);
105 if (len > 0 && filename[len - 1] == '/')
113 fd = orig_open (filename, flags, mode);
116 /* Implementing fchdir and fdopendir requires the ability to open a
117 directory file descriptor. If open doesn't support that (as on
118 mingw), we use a dummy file that behaves the same as directories
119 on Linux (ie. always reports EOF on attempts to read()), and
120 override fstat() in fchdir.c to hide the fact that we have a
122 if (REPLACE_OPEN_DIRECTORY && fd < 0 && errno == EACCES
123 && ((flags & O_ACCMODE) == O_RDONLY
124 || (O_SEARCH != O_RDONLY && (flags & O_ACCMODE) == O_SEARCH)))
127 if (stat (filename, &statbuf) == 0 && S_ISDIR (statbuf.st_mode))
129 /* Maximum recursion depth of 1. */
130 fd = open ("/dev/null", flags, mode);
132 fd = _gl_register_fd (fd, filename);
139 #if OPEN_TRAILING_SLASH_BUG
140 /* If the filename ends in a slash and fd does not refer to a directory,
142 Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html>
144 "A pathname that contains at least one non-slash character and that
145 ends with one or more trailing slashes shall be resolved as if a
146 single dot character ( '.' ) were appended to the pathname."
148 "The special filename dot shall refer to the directory specified by
150 If the named file without the slash is not a directory, open() must fail
154 /* We know len is positive, since open did not fail with ENOENT. */
155 size_t len = strlen (filename);
156 if (filename[len - 1] == '/')
160 if (fstat (fd, &statbuf) >= 0 && !S_ISDIR (statbuf.st_mode))
171 if (!REPLACE_OPEN_DIRECTORY && 0 <= fd)
172 fd = _gl_register_fd (fd, filename);