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53e1b683 | 1 | /* SPDX-License-Identifier: LGPL-2.1+ */ |
3ffd4af2 LP |
2 | /*** |
3 | This file is part of systemd. | |
4 | ||
5 | Copyright 2010 Lennart Poettering | |
6 | ||
7 | systemd is free software; you can redistribute it and/or modify it | |
8 | under the terms of the GNU Lesser General Public License as published by | |
9 | the Free Software Foundation; either version 2.1 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | systemd is distributed in the hope that it will be useful, but | |
13 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
15 | Lesser General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU Lesser General Public License | |
18 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
19 | ***/ | |
20 | ||
11c3a366 TA |
21 | #include <errno.h> |
22 | #include <fcntl.h> | |
23 | #include <sys/resource.h> | |
24 | #include <sys/socket.h> | |
25 | #include <sys/stat.h> | |
26 | #include <unistd.h> | |
27 | ||
8fb3f009 | 28 | #include "dirent-util.h" |
3ffd4af2 | 29 | #include "fd-util.h" |
4aeb20f5 | 30 | #include "fs-util.h" |
11c3a366 TA |
31 | #include "macro.h" |
32 | #include "missing.h" | |
93cc7779 | 33 | #include "parse-util.h" |
11c3a366 | 34 | #include "path-util.h" |
df0ff127 | 35 | #include "process-util.h" |
93cc7779 | 36 | #include "socket-util.h" |
4aeb20f5 | 37 | #include "stdio-util.h" |
3ffd4af2 LP |
38 | #include "util.h" |
39 | ||
40 | int close_nointr(int fd) { | |
41 | assert(fd >= 0); | |
42 | ||
43 | if (close(fd) >= 0) | |
44 | return 0; | |
45 | ||
46 | /* | |
47 | * Just ignore EINTR; a retry loop is the wrong thing to do on | |
48 | * Linux. | |
49 | * | |
50 | * http://lkml.indiana.edu/hypermail/linux/kernel/0509.1/0877.html | |
51 | * https://bugzilla.gnome.org/show_bug.cgi?id=682819 | |
52 | * http://utcc.utoronto.ca/~cks/space/blog/unix/CloseEINTR | |
53 | * https://sites.google.com/site/michaelsafyan/software-engineering/checkforeintrwheninvokingclosethinkagain | |
54 | */ | |
55 | if (errno == EINTR) | |
56 | return 0; | |
57 | ||
58 | return -errno; | |
59 | } | |
60 | ||
61 | int safe_close(int fd) { | |
62 | ||
63 | /* | |
64 | * Like close_nointr() but cannot fail. Guarantees errno is | |
65 | * unchanged. Is a NOP with negative fds passed, and returns | |
66 | * -1, so that it can be used in this syntax: | |
67 | * | |
68 | * fd = safe_close(fd); | |
69 | */ | |
70 | ||
71 | if (fd >= 0) { | |
72 | PROTECT_ERRNO; | |
73 | ||
74 | /* The kernel might return pretty much any error code | |
75 | * via close(), but the fd will be closed anyway. The | |
76 | * only condition we want to check for here is whether | |
77 | * the fd was invalid at all... */ | |
78 | ||
79 | assert_se(close_nointr(fd) != -EBADF); | |
80 | } | |
81 | ||
82 | return -1; | |
83 | } | |
84 | ||
85 | void safe_close_pair(int p[]) { | |
86 | assert(p); | |
87 | ||
88 | if (p[0] == p[1]) { | |
89 | /* Special case pairs which use the same fd in both | |
90 | * directions... */ | |
91 | p[0] = p[1] = safe_close(p[0]); | |
92 | return; | |
93 | } | |
94 | ||
95 | p[0] = safe_close(p[0]); | |
96 | p[1] = safe_close(p[1]); | |
97 | } | |
98 | ||
99 | void close_many(const int fds[], unsigned n_fd) { | |
100 | unsigned i; | |
101 | ||
102 | assert(fds || n_fd <= 0); | |
103 | ||
104 | for (i = 0; i < n_fd; i++) | |
105 | safe_close(fds[i]); | |
106 | } | |
107 | ||
108 | int fclose_nointr(FILE *f) { | |
109 | assert(f); | |
110 | ||
111 | /* Same as close_nointr(), but for fclose() */ | |
112 | ||
113 | if (fclose(f) == 0) | |
114 | return 0; | |
115 | ||
116 | if (errno == EINTR) | |
117 | return 0; | |
118 | ||
119 | return -errno; | |
120 | } | |
121 | ||
122 | FILE* safe_fclose(FILE *f) { | |
123 | ||
124 | /* Same as safe_close(), but for fclose() */ | |
125 | ||
126 | if (f) { | |
127 | PROTECT_ERRNO; | |
128 | ||
129 | assert_se(fclose_nointr(f) != EBADF); | |
130 | } | |
131 | ||
132 | return NULL; | |
133 | } | |
134 | ||
135 | DIR* safe_closedir(DIR *d) { | |
136 | ||
137 | if (d) { | |
138 | PROTECT_ERRNO; | |
139 | ||
140 | assert_se(closedir(d) >= 0 || errno != EBADF); | |
141 | } | |
142 | ||
143 | return NULL; | |
144 | } | |
145 | ||
146 | int fd_nonblock(int fd, bool nonblock) { | |
147 | int flags, nflags; | |
148 | ||
149 | assert(fd >= 0); | |
150 | ||
151 | flags = fcntl(fd, F_GETFL, 0); | |
152 | if (flags < 0) | |
153 | return -errno; | |
154 | ||
155 | if (nonblock) | |
156 | nflags = flags | O_NONBLOCK; | |
157 | else | |
158 | nflags = flags & ~O_NONBLOCK; | |
159 | ||
160 | if (nflags == flags) | |
161 | return 0; | |
162 | ||
163 | if (fcntl(fd, F_SETFL, nflags) < 0) | |
164 | return -errno; | |
165 | ||
166 | return 0; | |
167 | } | |
168 | ||
169 | int fd_cloexec(int fd, bool cloexec) { | |
170 | int flags, nflags; | |
171 | ||
172 | assert(fd >= 0); | |
173 | ||
174 | flags = fcntl(fd, F_GETFD, 0); | |
175 | if (flags < 0) | |
176 | return -errno; | |
177 | ||
178 | if (cloexec) | |
179 | nflags = flags | FD_CLOEXEC; | |
180 | else | |
181 | nflags = flags & ~FD_CLOEXEC; | |
182 | ||
183 | if (nflags == flags) | |
184 | return 0; | |
185 | ||
186 | if (fcntl(fd, F_SETFD, nflags) < 0) | |
187 | return -errno; | |
188 | ||
189 | return 0; | |
190 | } | |
191 | ||
3b9a1d87 AK |
192 | void stdio_unset_cloexec(void) { |
193 | fd_cloexec(STDIN_FILENO, false); | |
194 | fd_cloexec(STDOUT_FILENO, false); | |
195 | fd_cloexec(STDERR_FILENO, false); | |
196 | } | |
197 | ||
3ffd4af2 LP |
198 | _pure_ static bool fd_in_set(int fd, const int fdset[], unsigned n_fdset) { |
199 | unsigned i; | |
200 | ||
201 | assert(n_fdset == 0 || fdset); | |
202 | ||
203 | for (i = 0; i < n_fdset; i++) | |
204 | if (fdset[i] == fd) | |
205 | return true; | |
206 | ||
207 | return false; | |
208 | } | |
209 | ||
210 | int close_all_fds(const int except[], unsigned n_except) { | |
211 | _cleanup_closedir_ DIR *d = NULL; | |
212 | struct dirent *de; | |
213 | int r = 0; | |
214 | ||
215 | assert(n_except == 0 || except); | |
216 | ||
217 | d = opendir("/proc/self/fd"); | |
218 | if (!d) { | |
219 | int fd; | |
220 | struct rlimit rl; | |
221 | ||
222 | /* When /proc isn't available (for example in chroots) | |
223 | * the fallback is brute forcing through the fd | |
224 | * table */ | |
225 | ||
226 | assert_se(getrlimit(RLIMIT_NOFILE, &rl) >= 0); | |
227 | for (fd = 3; fd < (int) rl.rlim_max; fd ++) { | |
228 | ||
229 | if (fd_in_set(fd, except, n_except)) | |
230 | continue; | |
231 | ||
232 | if (close_nointr(fd) < 0) | |
233 | if (errno != EBADF && r == 0) | |
234 | r = -errno; | |
235 | } | |
236 | ||
237 | return r; | |
238 | } | |
239 | ||
8fb3f009 | 240 | FOREACH_DIRENT(de, d, return -errno) { |
3ffd4af2 LP |
241 | int fd = -1; |
242 | ||
3ffd4af2 LP |
243 | if (safe_atoi(de->d_name, &fd) < 0) |
244 | /* Let's better ignore this, just in case */ | |
245 | continue; | |
246 | ||
247 | if (fd < 3) | |
248 | continue; | |
249 | ||
250 | if (fd == dirfd(d)) | |
251 | continue; | |
252 | ||
253 | if (fd_in_set(fd, except, n_except)) | |
254 | continue; | |
255 | ||
256 | if (close_nointr(fd) < 0) { | |
257 | /* Valgrind has its own FD and doesn't want to have it closed */ | |
258 | if (errno != EBADF && r == 0) | |
259 | r = -errno; | |
260 | } | |
261 | } | |
262 | ||
263 | return r; | |
264 | } | |
265 | ||
266 | int same_fd(int a, int b) { | |
267 | struct stat sta, stb; | |
268 | pid_t pid; | |
269 | int r, fa, fb; | |
270 | ||
271 | assert(a >= 0); | |
272 | assert(b >= 0); | |
273 | ||
274 | /* Compares two file descriptors. Note that semantics are | |
275 | * quite different depending on whether we have kcmp() or we | |
276 | * don't. If we have kcmp() this will only return true for | |
277 | * dup()ed file descriptors, but not otherwise. If we don't | |
278 | * have kcmp() this will also return true for two fds of the same | |
279 | * file, created by separate open() calls. Since we use this | |
280 | * call mostly for filtering out duplicates in the fd store | |
281 | * this difference hopefully doesn't matter too much. */ | |
282 | ||
283 | if (a == b) | |
284 | return true; | |
285 | ||
286 | /* Try to use kcmp() if we have it. */ | |
df0ff127 | 287 | pid = getpid_cached(); |
3ffd4af2 LP |
288 | r = kcmp(pid, pid, KCMP_FILE, a, b); |
289 | if (r == 0) | |
290 | return true; | |
291 | if (r > 0) | |
292 | return false; | |
293 | if (errno != ENOSYS) | |
294 | return -errno; | |
295 | ||
296 | /* We don't have kcmp(), use fstat() instead. */ | |
297 | if (fstat(a, &sta) < 0) | |
298 | return -errno; | |
299 | ||
300 | if (fstat(b, &stb) < 0) | |
301 | return -errno; | |
302 | ||
303 | if ((sta.st_mode & S_IFMT) != (stb.st_mode & S_IFMT)) | |
304 | return false; | |
305 | ||
306 | /* We consider all device fds different, since two device fds | |
307 | * might refer to quite different device contexts even though | |
308 | * they share the same inode and backing dev_t. */ | |
309 | ||
310 | if (S_ISCHR(sta.st_mode) || S_ISBLK(sta.st_mode)) | |
311 | return false; | |
312 | ||
313 | if (sta.st_dev != stb.st_dev || sta.st_ino != stb.st_ino) | |
314 | return false; | |
315 | ||
316 | /* The fds refer to the same inode on disk, let's also check | |
317 | * if they have the same fd flags. This is useful to | |
318 | * distinguish the read and write side of a pipe created with | |
319 | * pipe(). */ | |
320 | fa = fcntl(a, F_GETFL); | |
321 | if (fa < 0) | |
322 | return -errno; | |
323 | ||
324 | fb = fcntl(b, F_GETFL); | |
325 | if (fb < 0) | |
326 | return -errno; | |
327 | ||
328 | return fa == fb; | |
329 | } | |
330 | ||
331 | void cmsg_close_all(struct msghdr *mh) { | |
332 | struct cmsghdr *cmsg; | |
333 | ||
334 | assert(mh); | |
335 | ||
336 | CMSG_FOREACH(cmsg, mh) | |
337 | if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) | |
338 | close_many((int*) CMSG_DATA(cmsg), (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int)); | |
339 | } | |
4fee3975 LP |
340 | |
341 | bool fdname_is_valid(const char *s) { | |
342 | const char *p; | |
343 | ||
344 | /* Validates a name for $LISTEN_FDNAMES. We basically allow | |
345 | * everything ASCII that's not a control character. Also, as | |
346 | * special exception the ":" character is not allowed, as we | |
347 | * use that as field separator in $LISTEN_FDNAMES. | |
348 | * | |
349 | * Note that the empty string is explicitly allowed | |
350 | * here. However, we limit the length of the names to 255 | |
351 | * characters. */ | |
352 | ||
353 | if (!s) | |
354 | return false; | |
355 | ||
356 | for (p = s; *p; p++) { | |
357 | if (*p < ' ') | |
358 | return false; | |
359 | if (*p >= 127) | |
360 | return false; | |
361 | if (*p == ':') | |
362 | return false; | |
363 | } | |
364 | ||
365 | return p - s < 256; | |
366 | } | |
4aeb20f5 LP |
367 | |
368 | int fd_get_path(int fd, char **ret) { | |
369 | char procfs_path[strlen("/proc/self/fd/") + DECIMAL_STR_MAX(int)]; | |
a0fe2a2d | 370 | int r; |
4aeb20f5 LP |
371 | |
372 | xsprintf(procfs_path, "/proc/self/fd/%i", fd); | |
373 | ||
a0fe2a2d LP |
374 | r = readlink_malloc(procfs_path, ret); |
375 | ||
376 | if (r == -ENOENT) /* If the file doesn't exist the fd is invalid */ | |
377 | return -EBADF; | |
378 | ||
379 | return r; | |
4aeb20f5 | 380 | } |