Commit | Line | Data |
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6ec2e0f5 | 1 | /* Open a descriptor to a file. |
7a6dbc2f | 2 | Copyright (C) 2007-2018 Free Software Foundation, Inc. |
6ec2e0f5 SDJ |
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 | |
7a6dbc2f | 15 | along with this program. If not, see <https://www.gnu.org/licenses/>. */ |
6ec2e0f5 SDJ |
16 | |
17 | /* Written by Bruno Haible <bruno@clisp.org>, 2007. */ | |
18 | ||
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 | |
21 | rpl_open. */ | |
22 | #define __need_system_fcntl_h | |
23 | #include <config.h> | |
24 | ||
25 | /* Get the original definition of open. It might be defined as a macro. */ | |
26 | #include <fcntl.h> | |
27 | #include <sys/types.h> | |
28 | #undef __need_system_fcntl_h | |
29 | ||
30 | static int | |
31 | orig_open (const char *filename, int flags, mode_t mode) | |
32 | { | |
33 | return open (filename, flags, mode); | |
34 | } | |
35 | ||
36 | /* Specification. */ | |
37 | /* Write "fcntl.h" here, not <fcntl.h>, otherwise OSF/1 5.1 DTK cc eliminates | |
38 | this include because of the preliminary #include <fcntl.h> above. */ | |
39 | #include "fcntl.h" | |
40 | ||
7a6dbc2f SDJ |
41 | #include "cloexec.h" |
42 | ||
6ec2e0f5 SDJ |
43 | #include <errno.h> |
44 | #include <stdarg.h> | |
45 | #include <string.h> | |
46 | #include <sys/types.h> | |
47 | #include <sys/stat.h> | |
48 | #include <unistd.h> | |
49 | ||
50 | #ifndef REPLACE_OPEN_DIRECTORY | |
51 | # define REPLACE_OPEN_DIRECTORY 0 | |
52 | #endif | |
53 | ||
54 | int | |
55 | open (const char *filename, int flags, ...) | |
56 | { | |
7a6dbc2f SDJ |
57 | /* 0 = unknown, 1 = yes, -1 = no. */ |
58 | #if GNULIB_defined_O_CLOEXEC | |
59 | int have_cloexec = -1; | |
60 | #else | |
61 | static int have_cloexec; | |
62 | #endif | |
63 | ||
6ec2e0f5 SDJ |
64 | mode_t mode; |
65 | int fd; | |
66 | ||
67 | mode = 0; | |
68 | if (flags & O_CREAT) | |
69 | { | |
70 | va_list arg; | |
71 | va_start (arg, flags); | |
72 | ||
73 | /* We have to use PROMOTED_MODE_T instead of mode_t, otherwise GCC 4 | |
74 | creates crashing code when 'mode_t' is smaller than 'int'. */ | |
75 | mode = va_arg (arg, PROMOTED_MODE_T); | |
76 | ||
77 | va_end (arg); | |
78 | } | |
79 | ||
80 | #if GNULIB_defined_O_NONBLOCK | |
81 | /* The only known platform that lacks O_NONBLOCK is mingw, but it | |
82 | also lacks named pipes and Unix sockets, which are the only two | |
83 | file types that require non-blocking handling in open(). | |
84 | Therefore, it is safe to ignore O_NONBLOCK here. It is handy | |
85 | that mingw also lacks openat(), so that is also covered here. */ | |
86 | flags &= ~O_NONBLOCK; | |
87 | #endif | |
88 | ||
7a6dbc2f | 89 | #if defined _WIN32 && ! defined __CYGWIN__ |
6ec2e0f5 SDJ |
90 | if (strcmp (filename, "/dev/null") == 0) |
91 | filename = "NUL"; | |
92 | #endif | |
93 | ||
94 | #if OPEN_TRAILING_SLASH_BUG | |
95 | /* If the filename ends in a slash and one of O_CREAT, O_WRONLY, O_RDWR | |
96 | is specified, then fail. | |
97 | Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html> | |
98 | says that | |
99 | "A pathname that contains at least one non-slash character and that | |
100 | ends with one or more trailing slashes shall be resolved as if a | |
101 | single dot character ( '.' ) were appended to the pathname." | |
102 | and | |
103 | "The special filename dot shall refer to the directory specified by | |
104 | its predecessor." | |
105 | If the named file already exists as a directory, then | |
106 | - if O_CREAT is specified, open() must fail because of the semantics | |
107 | of O_CREAT, | |
108 | - if O_WRONLY or O_RDWR is specified, open() must fail because POSIX | |
109 | <http://www.opengroup.org/susv3/functions/open.html> says that it | |
110 | fails with errno = EISDIR in this case. | |
111 | If the named file does not exist or does not name a directory, then | |
112 | - if O_CREAT is specified, open() must fail since open() cannot create | |
113 | directories, | |
114 | - if O_WRONLY or O_RDWR is specified, open() must fail because the | |
115 | file does not contain a '.' directory. */ | |
116 | if (flags & (O_CREAT | O_WRONLY | O_RDWR)) | |
117 | { | |
118 | size_t len = strlen (filename); | |
119 | if (len > 0 && filename[len - 1] == '/') | |
120 | { | |
121 | errno = EISDIR; | |
122 | return -1; | |
123 | } | |
124 | } | |
125 | #endif | |
126 | ||
7a6dbc2f SDJ |
127 | fd = orig_open (filename, |
128 | flags & ~(have_cloexec <= 0 ? O_CLOEXEC : 0), mode); | |
129 | ||
130 | if (flags & O_CLOEXEC) | |
131 | { | |
132 | if (! have_cloexec) | |
133 | { | |
134 | if (0 <= fd) | |
135 | have_cloexec = 1; | |
136 | else if (errno == EINVAL) | |
137 | { | |
138 | fd = orig_open (filename, flags & ~O_CLOEXEC, mode); | |
139 | have_cloexec = -1; | |
140 | } | |
141 | } | |
142 | if (have_cloexec < 0 && 0 <= fd) | |
143 | set_cloexec_flag (fd, true); | |
144 | } | |
145 | ||
6ec2e0f5 SDJ |
146 | |
147 | #if REPLACE_FCHDIR | |
148 | /* Implementing fchdir and fdopendir requires the ability to open a | |
149 | directory file descriptor. If open doesn't support that (as on | |
150 | mingw), we use a dummy file that behaves the same as directories | |
151 | on Linux (ie. always reports EOF on attempts to read()), and | |
152 | override fstat() in fchdir.c to hide the fact that we have a | |
153 | dummy. */ | |
154 | if (REPLACE_OPEN_DIRECTORY && fd < 0 && errno == EACCES | |
155 | && ((flags & O_ACCMODE) == O_RDONLY | |
156 | || (O_SEARCH != O_RDONLY && (flags & O_ACCMODE) == O_SEARCH))) | |
157 | { | |
158 | struct stat statbuf; | |
159 | if (stat (filename, &statbuf) == 0 && S_ISDIR (statbuf.st_mode)) | |
160 | { | |
161 | /* Maximum recursion depth of 1. */ | |
162 | fd = open ("/dev/null", flags, mode); | |
163 | if (0 <= fd) | |
164 | fd = _gl_register_fd (fd, filename); | |
165 | } | |
166 | else | |
167 | errno = EACCES; | |
168 | } | |
169 | #endif | |
170 | ||
171 | #if OPEN_TRAILING_SLASH_BUG | |
172 | /* If the filename ends in a slash and fd does not refer to a directory, | |
173 | then fail. | |
174 | Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html> | |
175 | says that | |
176 | "A pathname that contains at least one non-slash character and that | |
177 | ends with one or more trailing slashes shall be resolved as if a | |
178 | single dot character ( '.' ) were appended to the pathname." | |
179 | and | |
180 | "The special filename dot shall refer to the directory specified by | |
181 | its predecessor." | |
182 | If the named file without the slash is not a directory, open() must fail | |
183 | with ENOTDIR. */ | |
184 | if (fd >= 0) | |
185 | { | |
186 | /* We know len is positive, since open did not fail with ENOENT. */ | |
187 | size_t len = strlen (filename); | |
188 | if (filename[len - 1] == '/') | |
189 | { | |
190 | struct stat statbuf; | |
191 | ||
192 | if (fstat (fd, &statbuf) >= 0 && !S_ISDIR (statbuf.st_mode)) | |
193 | { | |
194 | close (fd); | |
195 | errno = ENOTDIR; | |
196 | return -1; | |
197 | } | |
198 | } | |
199 | } | |
200 | #endif | |
201 | ||
202 | #if REPLACE_FCHDIR | |
203 | if (!REPLACE_OPEN_DIRECTORY && 0 <= fd) | |
204 | fd = _gl_register_fd (fd, filename); | |
205 | #endif | |
206 | ||
207 | return fd; | |
208 | } |