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. */
19 /* If the user's config.h happens to include <fcntl.h>, let it include only
20 the system's <fcntl.h> here, so that orig_open doesn't recurse to
22 #define __need_system_fcntl_h
25 /* Get the original definition of open. It might be defined as a macro. */
27 #include <sys/types.h>
28 #undef __need_system_fcntl_h
31 orig_open (const char *filename, int flags, mode_t mode)
33 return open (filename, flags, mode);
42 #include <sys/types.h>
46 #ifndef REPLACE_OPEN_DIRECTORY
47 # define REPLACE_OPEN_DIRECTORY 0
51 open (const char *filename, int flags, ...)
60 va_start (arg, flags);
62 /* We have to use PROMOTED_MODE_T instead of mode_t, otherwise GCC 4
63 creates crashing code when 'mode_t' is smaller than 'int'. */
64 mode = va_arg (arg, PROMOTED_MODE_T);
69 #if GNULIB_defined_O_NONBLOCK
70 /* The only known platform that lacks O_NONBLOCK is mingw, but it
71 also lacks named pipes and Unix sockets, which are the only two
72 file types that require non-blocking handling in open().
73 Therefore, it is safe to ignore O_NONBLOCK here. It is handy
74 that mingw also lacks openat(), so that is also covered here. */
78 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
79 if (strcmp (filename, "/dev/null") == 0)
83 #if OPEN_TRAILING_SLASH_BUG
84 /* If the filename ends in a slash and one of O_CREAT, O_WRONLY, O_RDWR
85 is specified, then fail.
86 Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html>
88 "A pathname that contains at least one non-slash character and that
89 ends with one or more trailing slashes shall be resolved as if a
90 single dot character ( '.' ) were appended to the pathname."
92 "The special filename dot shall refer to the directory specified by
94 If the named file already exists as a directory, then
95 - if O_CREAT is specified, open() must fail because of the semantics
97 - if O_WRONLY or O_RDWR is specified, open() must fail because POSIX
98 <http://www.opengroup.org/susv3/functions/open.html> says that it
99 fails with errno = EISDIR in this case.
100 If the named file does not exist or does not name a directory, then
101 - if O_CREAT is specified, open() must fail since open() cannot create
103 - if O_WRONLY or O_RDWR is specified, open() must fail because the
104 file does not contain a '.' directory. */
105 if (flags & (O_CREAT | O_WRONLY | O_RDWR))
107 size_t len = strlen (filename);
108 if (len > 0 && filename[len - 1] == '/')
116 fd = orig_open (filename, flags, mode);
119 /* Implementing fchdir and fdopendir requires the ability to open a
120 directory file descriptor. If open doesn't support that (as on
121 mingw), we use a dummy file that behaves the same as directories
122 on Linux (ie. always reports EOF on attempts to read()), and
123 override fstat() in fchdir.c to hide the fact that we have a
125 if (REPLACE_OPEN_DIRECTORY && fd < 0 && errno == EACCES
126 && ((flags & O_ACCMODE) == O_RDONLY
127 || (O_SEARCH != O_RDONLY && (flags & O_ACCMODE) == O_SEARCH)))
130 if (stat (filename, &statbuf) == 0 && S_ISDIR (statbuf.st_mode))
132 /* Maximum recursion depth of 1. */
133 fd = open ("/dev/null", flags, mode);
135 fd = _gl_register_fd (fd, filename);
142 #if OPEN_TRAILING_SLASH_BUG
143 /* If the filename ends in a slash and fd does not refer to a directory,
145 Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html>
147 "A pathname that contains at least one non-slash character and that
148 ends with one or more trailing slashes shall be resolved as if a
149 single dot character ( '.' ) were appended to the pathname."
151 "The special filename dot shall refer to the directory specified by
153 If the named file without the slash is not a directory, open() must fail
157 /* We know len is positive, since open did not fail with ENOENT. */
158 size_t len = strlen (filename);
159 if (filename[len - 1] == '/')
163 if (fstat (fd, &statbuf) >= 0 && !S_ISDIR (statbuf.st_mode))
174 if (!REPLACE_OPEN_DIRECTORY && 0 <= fd)
175 fd = _gl_register_fd (fd, filename);