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3ffd4af2 LP |
1 | /*** |
2 | This file is part of systemd. | |
3 | ||
4 | Copyright 2010 Lennart Poettering | |
5 | ||
6 | systemd is free software; you can redistribute it and/or modify it | |
7 | under the terms of the GNU Lesser General Public License as published by | |
8 | the Free Software Foundation; either version 2.1 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | systemd is distributed in the hope that it will be useful, but | |
12 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | Lesser General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU Lesser General Public License | |
17 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
18 | ***/ | |
19 | ||
11c3a366 TA |
20 | #include <errno.h> |
21 | #include <fcntl.h> | |
22 | #include <sys/resource.h> | |
23 | #include <sys/socket.h> | |
24 | #include <sys/stat.h> | |
25 | #include <unistd.h> | |
26 | ||
8fb3f009 | 27 | #include "dirent-util.h" |
3ffd4af2 | 28 | #include "fd-util.h" |
4aeb20f5 | 29 | #include "fs-util.h" |
11c3a366 TA |
30 | #include "macro.h" |
31 | #include "missing.h" | |
93cc7779 | 32 | #include "parse-util.h" |
11c3a366 | 33 | #include "path-util.h" |
93cc7779 | 34 | #include "socket-util.h" |
4aeb20f5 | 35 | #include "stdio-util.h" |
3ffd4af2 LP |
36 | #include "util.h" |
37 | ||
38 | int close_nointr(int fd) { | |
39 | assert(fd >= 0); | |
40 | ||
41 | if (close(fd) >= 0) | |
42 | return 0; | |
43 | ||
44 | /* | |
45 | * Just ignore EINTR; a retry loop is the wrong thing to do on | |
46 | * Linux. | |
47 | * | |
48 | * http://lkml.indiana.edu/hypermail/linux/kernel/0509.1/0877.html | |
49 | * https://bugzilla.gnome.org/show_bug.cgi?id=682819 | |
50 | * http://utcc.utoronto.ca/~cks/space/blog/unix/CloseEINTR | |
51 | * https://sites.google.com/site/michaelsafyan/software-engineering/checkforeintrwheninvokingclosethinkagain | |
52 | */ | |
53 | if (errno == EINTR) | |
54 | return 0; | |
55 | ||
56 | return -errno; | |
57 | } | |
58 | ||
59 | int safe_close(int fd) { | |
60 | ||
61 | /* | |
62 | * Like close_nointr() but cannot fail. Guarantees errno is | |
63 | * unchanged. Is a NOP with negative fds passed, and returns | |
64 | * -1, so that it can be used in this syntax: | |
65 | * | |
66 | * fd = safe_close(fd); | |
67 | */ | |
68 | ||
69 | if (fd >= 0) { | |
70 | PROTECT_ERRNO; | |
71 | ||
72 | /* The kernel might return pretty much any error code | |
73 | * via close(), but the fd will be closed anyway. The | |
74 | * only condition we want to check for here is whether | |
75 | * the fd was invalid at all... */ | |
76 | ||
77 | assert_se(close_nointr(fd) != -EBADF); | |
78 | } | |
79 | ||
80 | return -1; | |
81 | } | |
82 | ||
83 | void safe_close_pair(int p[]) { | |
84 | assert(p); | |
85 | ||
86 | if (p[0] == p[1]) { | |
87 | /* Special case pairs which use the same fd in both | |
88 | * directions... */ | |
89 | p[0] = p[1] = safe_close(p[0]); | |
90 | return; | |
91 | } | |
92 | ||
93 | p[0] = safe_close(p[0]); | |
94 | p[1] = safe_close(p[1]); | |
95 | } | |
96 | ||
97 | void close_many(const int fds[], unsigned n_fd) { | |
98 | unsigned i; | |
99 | ||
100 | assert(fds || n_fd <= 0); | |
101 | ||
102 | for (i = 0; i < n_fd; i++) | |
103 | safe_close(fds[i]); | |
104 | } | |
105 | ||
106 | int fclose_nointr(FILE *f) { | |
107 | assert(f); | |
108 | ||
109 | /* Same as close_nointr(), but for fclose() */ | |
110 | ||
111 | if (fclose(f) == 0) | |
112 | return 0; | |
113 | ||
114 | if (errno == EINTR) | |
115 | return 0; | |
116 | ||
117 | return -errno; | |
118 | } | |
119 | ||
120 | FILE* safe_fclose(FILE *f) { | |
121 | ||
122 | /* Same as safe_close(), but for fclose() */ | |
123 | ||
124 | if (f) { | |
125 | PROTECT_ERRNO; | |
126 | ||
127 | assert_se(fclose_nointr(f) != EBADF); | |
128 | } | |
129 | ||
130 | return NULL; | |
131 | } | |
132 | ||
133 | DIR* safe_closedir(DIR *d) { | |
134 | ||
135 | if (d) { | |
136 | PROTECT_ERRNO; | |
137 | ||
138 | assert_se(closedir(d) >= 0 || errno != EBADF); | |
139 | } | |
140 | ||
141 | return NULL; | |
142 | } | |
143 | ||
144 | int fd_nonblock(int fd, bool nonblock) { | |
145 | int flags, nflags; | |
146 | ||
147 | assert(fd >= 0); | |
148 | ||
149 | flags = fcntl(fd, F_GETFL, 0); | |
150 | if (flags < 0) | |
151 | return -errno; | |
152 | ||
153 | if (nonblock) | |
154 | nflags = flags | O_NONBLOCK; | |
155 | else | |
156 | nflags = flags & ~O_NONBLOCK; | |
157 | ||
158 | if (nflags == flags) | |
159 | return 0; | |
160 | ||
161 | if (fcntl(fd, F_SETFL, nflags) < 0) | |
162 | return -errno; | |
163 | ||
164 | return 0; | |
165 | } | |
166 | ||
167 | int fd_cloexec(int fd, bool cloexec) { | |
168 | int flags, nflags; | |
169 | ||
170 | assert(fd >= 0); | |
171 | ||
172 | flags = fcntl(fd, F_GETFD, 0); | |
173 | if (flags < 0) | |
174 | return -errno; | |
175 | ||
176 | if (cloexec) | |
177 | nflags = flags | FD_CLOEXEC; | |
178 | else | |
179 | nflags = flags & ~FD_CLOEXEC; | |
180 | ||
181 | if (nflags == flags) | |
182 | return 0; | |
183 | ||
184 | if (fcntl(fd, F_SETFD, nflags) < 0) | |
185 | return -errno; | |
186 | ||
187 | return 0; | |
188 | } | |
189 | ||
3b9a1d87 AK |
190 | void stdio_unset_cloexec(void) { |
191 | fd_cloexec(STDIN_FILENO, false); | |
192 | fd_cloexec(STDOUT_FILENO, false); | |
193 | fd_cloexec(STDERR_FILENO, false); | |
194 | } | |
195 | ||
3ffd4af2 LP |
196 | _pure_ static bool fd_in_set(int fd, const int fdset[], unsigned n_fdset) { |
197 | unsigned i; | |
198 | ||
199 | assert(n_fdset == 0 || fdset); | |
200 | ||
201 | for (i = 0; i < n_fdset; i++) | |
202 | if (fdset[i] == fd) | |
203 | return true; | |
204 | ||
205 | return false; | |
206 | } | |
207 | ||
208 | int close_all_fds(const int except[], unsigned n_except) { | |
209 | _cleanup_closedir_ DIR *d = NULL; | |
210 | struct dirent *de; | |
211 | int r = 0; | |
212 | ||
213 | assert(n_except == 0 || except); | |
214 | ||
215 | d = opendir("/proc/self/fd"); | |
216 | if (!d) { | |
217 | int fd; | |
218 | struct rlimit rl; | |
219 | ||
220 | /* When /proc isn't available (for example in chroots) | |
221 | * the fallback is brute forcing through the fd | |
222 | * table */ | |
223 | ||
224 | assert_se(getrlimit(RLIMIT_NOFILE, &rl) >= 0); | |
225 | for (fd = 3; fd < (int) rl.rlim_max; fd ++) { | |
226 | ||
227 | if (fd_in_set(fd, except, n_except)) | |
228 | continue; | |
229 | ||
230 | if (close_nointr(fd) < 0) | |
231 | if (errno != EBADF && r == 0) | |
232 | r = -errno; | |
233 | } | |
234 | ||
235 | return r; | |
236 | } | |
237 | ||
8fb3f009 | 238 | FOREACH_DIRENT(de, d, return -errno) { |
3ffd4af2 LP |
239 | int fd = -1; |
240 | ||
3ffd4af2 LP |
241 | if (safe_atoi(de->d_name, &fd) < 0) |
242 | /* Let's better ignore this, just in case */ | |
243 | continue; | |
244 | ||
245 | if (fd < 3) | |
246 | continue; | |
247 | ||
248 | if (fd == dirfd(d)) | |
249 | continue; | |
250 | ||
251 | if (fd_in_set(fd, except, n_except)) | |
252 | continue; | |
253 | ||
254 | if (close_nointr(fd) < 0) { | |
255 | /* Valgrind has its own FD and doesn't want to have it closed */ | |
256 | if (errno != EBADF && r == 0) | |
257 | r = -errno; | |
258 | } | |
259 | } | |
260 | ||
261 | return r; | |
262 | } | |
263 | ||
264 | int same_fd(int a, int b) { | |
265 | struct stat sta, stb; | |
266 | pid_t pid; | |
267 | int r, fa, fb; | |
268 | ||
269 | assert(a >= 0); | |
270 | assert(b >= 0); | |
271 | ||
272 | /* Compares two file descriptors. Note that semantics are | |
273 | * quite different depending on whether we have kcmp() or we | |
274 | * don't. If we have kcmp() this will only return true for | |
275 | * dup()ed file descriptors, but not otherwise. If we don't | |
276 | * have kcmp() this will also return true for two fds of the same | |
277 | * file, created by separate open() calls. Since we use this | |
278 | * call mostly for filtering out duplicates in the fd store | |
279 | * this difference hopefully doesn't matter too much. */ | |
280 | ||
281 | if (a == b) | |
282 | return true; | |
283 | ||
284 | /* Try to use kcmp() if we have it. */ | |
285 | pid = getpid(); | |
286 | r = kcmp(pid, pid, KCMP_FILE, a, b); | |
287 | if (r == 0) | |
288 | return true; | |
289 | if (r > 0) | |
290 | return false; | |
291 | if (errno != ENOSYS) | |
292 | return -errno; | |
293 | ||
294 | /* We don't have kcmp(), use fstat() instead. */ | |
295 | if (fstat(a, &sta) < 0) | |
296 | return -errno; | |
297 | ||
298 | if (fstat(b, &stb) < 0) | |
299 | return -errno; | |
300 | ||
301 | if ((sta.st_mode & S_IFMT) != (stb.st_mode & S_IFMT)) | |
302 | return false; | |
303 | ||
304 | /* We consider all device fds different, since two device fds | |
305 | * might refer to quite different device contexts even though | |
306 | * they share the same inode and backing dev_t. */ | |
307 | ||
308 | if (S_ISCHR(sta.st_mode) || S_ISBLK(sta.st_mode)) | |
309 | return false; | |
310 | ||
311 | if (sta.st_dev != stb.st_dev || sta.st_ino != stb.st_ino) | |
312 | return false; | |
313 | ||
314 | /* The fds refer to the same inode on disk, let's also check | |
315 | * if they have the same fd flags. This is useful to | |
316 | * distinguish the read and write side of a pipe created with | |
317 | * pipe(). */ | |
318 | fa = fcntl(a, F_GETFL); | |
319 | if (fa < 0) | |
320 | return -errno; | |
321 | ||
322 | fb = fcntl(b, F_GETFL); | |
323 | if (fb < 0) | |
324 | return -errno; | |
325 | ||
326 | return fa == fb; | |
327 | } | |
328 | ||
329 | void cmsg_close_all(struct msghdr *mh) { | |
330 | struct cmsghdr *cmsg; | |
331 | ||
332 | assert(mh); | |
333 | ||
334 | CMSG_FOREACH(cmsg, mh) | |
335 | if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) | |
336 | close_many((int*) CMSG_DATA(cmsg), (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int)); | |
337 | } | |
4fee3975 LP |
338 | |
339 | bool fdname_is_valid(const char *s) { | |
340 | const char *p; | |
341 | ||
342 | /* Validates a name for $LISTEN_FDNAMES. We basically allow | |
343 | * everything ASCII that's not a control character. Also, as | |
344 | * special exception the ":" character is not allowed, as we | |
345 | * use that as field separator in $LISTEN_FDNAMES. | |
346 | * | |
347 | * Note that the empty string is explicitly allowed | |
348 | * here. However, we limit the length of the names to 255 | |
349 | * characters. */ | |
350 | ||
351 | if (!s) | |
352 | return false; | |
353 | ||
354 | for (p = s; *p; p++) { | |
355 | if (*p < ' ') | |
356 | return false; | |
357 | if (*p >= 127) | |
358 | return false; | |
359 | if (*p == ':') | |
360 | return false; | |
361 | } | |
362 | ||
363 | return p - s < 256; | |
364 | } | |
4aeb20f5 LP |
365 | |
366 | int fd_get_path(int fd, char **ret) { | |
367 | char procfs_path[strlen("/proc/self/fd/") + DECIMAL_STR_MAX(int)]; | |
a0fe2a2d | 368 | int r; |
4aeb20f5 LP |
369 | |
370 | xsprintf(procfs_path, "/proc/self/fd/%i", fd); | |
371 | ||
a0fe2a2d LP |
372 | r = readlink_malloc(procfs_path, ret); |
373 | ||
374 | if (r == -ENOENT) /* If the file doesn't exist the fd is invalid */ | |
375 | return -EBADF; | |
376 | ||
377 | return r; | |
4aeb20f5 | 378 | } |