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3d458a81 AW |
1 | /* Open a descriptor to a file. |
2 | Copyright (C) 2007-2011 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 Lesser 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 Lesser General Public License for more details. | |
13 | ||
14 | You should have received a copy of the GNU Lesser 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 open. It might be defined as a macro. */ | |
22 | #define __need_system_fcntl_h | |
23 | #include <fcntl.h> | |
24 | #undef __need_system_fcntl_h | |
25 | #include <sys/types.h> | |
26 | ||
27 | static inline int | |
28 | orig_open (const char *filename, int flags, mode_t mode) | |
29 | { | |
30 | return open (filename, flags, mode); | |
31 | } | |
32 | ||
33 | /* Specification. */ | |
34 | #include <fcntl.h> | |
35 | ||
36 | #include <errno.h> | |
37 | #include <stdarg.h> | |
38 | #include <string.h> | |
39 | #include <sys/types.h> | |
40 | #include <sys/stat.h> | |
41 | #include <unistd.h> | |
42 | ||
43 | #ifndef REPLACE_OPEN_DIRECTORY | |
44 | # define REPLACE_OPEN_DIRECTORY 0 | |
45 | #endif | |
46 | ||
47 | int | |
48 | open (const char *filename, int flags, ...) | |
49 | { | |
50 | mode_t mode; | |
51 | int fd; | |
52 | ||
53 | mode = 0; | |
54 | if (flags & O_CREAT) | |
55 | { | |
56 | va_list arg; | |
57 | va_start (arg, flags); | |
58 | ||
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); | |
62 | ||
63 | va_end (arg); | |
64 | } | |
65 | ||
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. */ | |
72 | flags &= ~O_NONBLOCK; | |
73 | #endif | |
74 | ||
75 | #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__ | |
76 | if (strcmp (filename, "/dev/null") == 0) | |
77 | filename = "NUL"; | |
78 | #endif | |
79 | ||
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> | |
84 | says that | |
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." | |
88 | and | |
89 | "The special filename dot shall refer to the directory specified by | |
90 | its predecessor." | |
91 | If the named file already exists as a directory, then | |
92 | - if O_CREAT is specified, open() must fail because of the semantics | |
93 | of O_CREAT, | |
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 | |
99 | directories, | |
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)) | |
103 | { | |
104 | size_t len = strlen (filename); | |
105 | if (len > 0 && filename[len - 1] == '/') | |
106 | { | |
107 | errno = EISDIR; | |
108 | return -1; | |
109 | } | |
110 | } | |
111 | #endif | |
112 | ||
113 | fd = orig_open (filename, flags, mode); | |
114 | ||
115 | #if REPLACE_FCHDIR | |
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 | |
121 | dummy. */ | |
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))) | |
125 | { | |
126 | struct stat statbuf; | |
127 | if (stat (filename, &statbuf) == 0 && S_ISDIR (statbuf.st_mode)) | |
128 | { | |
129 | /* Maximum recursion depth of 1. */ | |
130 | fd = open ("/dev/null", flags, mode); | |
131 | if (0 <= fd) | |
132 | fd = _gl_register_fd (fd, filename); | |
133 | } | |
134 | else | |
135 | errno = EACCES; | |
136 | } | |
137 | #endif | |
138 | ||
139 | #if OPEN_TRAILING_SLASH_BUG | |
140 | /* If the filename ends in a slash and fd does not refer to a directory, | |
141 | then fail. | |
142 | Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html> | |
143 | says that | |
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." | |
147 | and | |
148 | "The special filename dot shall refer to the directory specified by | |
149 | its predecessor." | |
150 | If the named file without the slash is not a directory, open() must fail | |
151 | with ENOTDIR. */ | |
152 | if (fd >= 0) | |
153 | { | |
154 | /* We know len is positive, since open did not fail with ENOENT. */ | |
155 | size_t len = strlen (filename); | |
156 | if (filename[len - 1] == '/') | |
157 | { | |
158 | struct stat statbuf; | |
159 | ||
160 | if (fstat (fd, &statbuf) >= 0 && !S_ISDIR (statbuf.st_mode)) | |
161 | { | |
162 | close (fd); | |
163 | errno = ENOTDIR; | |
164 | return -1; | |
165 | } | |
166 | } | |
167 | } | |
168 | #endif | |
169 | ||
170 | #if REPLACE_FCHDIR | |
171 | if (!REPLACE_OPEN_DIRECTORY && 0 <= fd) | |
172 | fd = _gl_register_fd (fd, filename); | |
173 | #endif | |
174 | ||
175 | return fd; | |
176 | } |