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1 | /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ |
2 | ||
3 | /*** | |
4 | This file is part of systemd. | |
5 | ||
6 | Copyright 2010 Lennart Poettering | |
7 | ||
8 | systemd is free software; you can redistribute it and/or modify it | |
9 | under the terms of the GNU Lesser General Public License as published by | |
10 | the Free Software Foundation; either version 2.1 of the License, or | |
11 | (at your option) any later version. | |
12 | ||
13 | systemd is distributed in the hope that it will be useful, but | |
14 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | Lesser General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU Lesser General Public License | |
19 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
20 | ***/ | |
21 | ||
8f328d36 | 22 | #include "dirent-util.h" |
3ffd4af2 | 23 | #include "fd-util.h" |
6bedfcbb | 24 | #include "parse-util.h" |
8f328d36 | 25 | #include "socket-util.h" |
3ffd4af2 LP |
26 | #include "util.h" |
27 | ||
28 | int close_nointr(int fd) { | |
29 | assert(fd >= 0); | |
30 | ||
31 | if (close(fd) >= 0) | |
32 | return 0; | |
33 | ||
34 | /* | |
35 | * Just ignore EINTR; a retry loop is the wrong thing to do on | |
36 | * Linux. | |
37 | * | |
38 | * http://lkml.indiana.edu/hypermail/linux/kernel/0509.1/0877.html | |
39 | * https://bugzilla.gnome.org/show_bug.cgi?id=682819 | |
40 | * http://utcc.utoronto.ca/~cks/space/blog/unix/CloseEINTR | |
41 | * https://sites.google.com/site/michaelsafyan/software-engineering/checkforeintrwheninvokingclosethinkagain | |
42 | */ | |
43 | if (errno == EINTR) | |
44 | return 0; | |
45 | ||
46 | return -errno; | |
47 | } | |
48 | ||
49 | int safe_close(int fd) { | |
50 | ||
51 | /* | |
52 | * Like close_nointr() but cannot fail. Guarantees errno is | |
53 | * unchanged. Is a NOP with negative fds passed, and returns | |
54 | * -1, so that it can be used in this syntax: | |
55 | * | |
56 | * fd = safe_close(fd); | |
57 | */ | |
58 | ||
59 | if (fd >= 0) { | |
60 | PROTECT_ERRNO; | |
61 | ||
62 | /* The kernel might return pretty much any error code | |
63 | * via close(), but the fd will be closed anyway. The | |
64 | * only condition we want to check for here is whether | |
65 | * the fd was invalid at all... */ | |
66 | ||
67 | assert_se(close_nointr(fd) != -EBADF); | |
68 | } | |
69 | ||
70 | return -1; | |
71 | } | |
72 | ||
73 | void safe_close_pair(int p[]) { | |
74 | assert(p); | |
75 | ||
76 | if (p[0] == p[1]) { | |
77 | /* Special case pairs which use the same fd in both | |
78 | * directions... */ | |
79 | p[0] = p[1] = safe_close(p[0]); | |
80 | return; | |
81 | } | |
82 | ||
83 | p[0] = safe_close(p[0]); | |
84 | p[1] = safe_close(p[1]); | |
85 | } | |
86 | ||
87 | void close_many(const int fds[], unsigned n_fd) { | |
88 | unsigned i; | |
89 | ||
90 | assert(fds || n_fd <= 0); | |
91 | ||
92 | for (i = 0; i < n_fd; i++) | |
93 | safe_close(fds[i]); | |
94 | } | |
95 | ||
96 | int fclose_nointr(FILE *f) { | |
97 | assert(f); | |
98 | ||
99 | /* Same as close_nointr(), but for fclose() */ | |
100 | ||
101 | if (fclose(f) == 0) | |
102 | return 0; | |
103 | ||
104 | if (errno == EINTR) | |
105 | return 0; | |
106 | ||
107 | return -errno; | |
108 | } | |
109 | ||
110 | FILE* safe_fclose(FILE *f) { | |
111 | ||
112 | /* Same as safe_close(), but for fclose() */ | |
113 | ||
114 | if (f) { | |
115 | PROTECT_ERRNO; | |
116 | ||
117 | assert_se(fclose_nointr(f) != EBADF); | |
118 | } | |
119 | ||
120 | return NULL; | |
121 | } | |
122 | ||
123 | DIR* safe_closedir(DIR *d) { | |
124 | ||
125 | if (d) { | |
126 | PROTECT_ERRNO; | |
127 | ||
128 | assert_se(closedir(d) >= 0 || errno != EBADF); | |
129 | } | |
130 | ||
131 | return NULL; | |
132 | } | |
133 | ||
134 | int fd_nonblock(int fd, bool nonblock) { | |
135 | int flags, nflags; | |
136 | ||
137 | assert(fd >= 0); | |
138 | ||
139 | flags = fcntl(fd, F_GETFL, 0); | |
140 | if (flags < 0) | |
141 | return -errno; | |
142 | ||
143 | if (nonblock) | |
144 | nflags = flags | O_NONBLOCK; | |
145 | else | |
146 | nflags = flags & ~O_NONBLOCK; | |
147 | ||
148 | if (nflags == flags) | |
149 | return 0; | |
150 | ||
151 | if (fcntl(fd, F_SETFL, nflags) < 0) | |
152 | return -errno; | |
153 | ||
154 | return 0; | |
155 | } | |
156 | ||
157 | int fd_cloexec(int fd, bool cloexec) { | |
158 | int flags, nflags; | |
159 | ||
160 | assert(fd >= 0); | |
161 | ||
162 | flags = fcntl(fd, F_GETFD, 0); | |
163 | if (flags < 0) | |
164 | return -errno; | |
165 | ||
166 | if (cloexec) | |
167 | nflags = flags | FD_CLOEXEC; | |
168 | else | |
169 | nflags = flags & ~FD_CLOEXEC; | |
170 | ||
171 | if (nflags == flags) | |
172 | return 0; | |
173 | ||
174 | if (fcntl(fd, F_SETFD, nflags) < 0) | |
175 | return -errno; | |
176 | ||
177 | return 0; | |
178 | } | |
179 | ||
180 | _pure_ static bool fd_in_set(int fd, const int fdset[], unsigned n_fdset) { | |
181 | unsigned i; | |
182 | ||
183 | assert(n_fdset == 0 || fdset); | |
184 | ||
185 | for (i = 0; i < n_fdset; i++) | |
186 | if (fdset[i] == fd) | |
187 | return true; | |
188 | ||
189 | return false; | |
190 | } | |
191 | ||
192 | int close_all_fds(const int except[], unsigned n_except) { | |
193 | _cleanup_closedir_ DIR *d = NULL; | |
194 | struct dirent *de; | |
195 | int r = 0; | |
196 | ||
197 | assert(n_except == 0 || except); | |
198 | ||
199 | d = opendir("/proc/self/fd"); | |
200 | if (!d) { | |
201 | int fd; | |
202 | struct rlimit rl; | |
203 | ||
204 | /* When /proc isn't available (for example in chroots) | |
205 | * the fallback is brute forcing through the fd | |
206 | * table */ | |
207 | ||
208 | assert_se(getrlimit(RLIMIT_NOFILE, &rl) >= 0); | |
209 | for (fd = 3; fd < (int) rl.rlim_max; fd ++) { | |
210 | ||
211 | if (fd_in_set(fd, except, n_except)) | |
212 | continue; | |
213 | ||
214 | if (close_nointr(fd) < 0) | |
215 | if (errno != EBADF && r == 0) | |
216 | r = -errno; | |
217 | } | |
218 | ||
219 | return r; | |
220 | } | |
221 | ||
222 | while ((de = readdir(d))) { | |
223 | int fd = -1; | |
224 | ||
225 | if (hidden_file(de->d_name)) | |
226 | continue; | |
227 | ||
228 | if (safe_atoi(de->d_name, &fd) < 0) | |
229 | /* Let's better ignore this, just in case */ | |
230 | continue; | |
231 | ||
232 | if (fd < 3) | |
233 | continue; | |
234 | ||
235 | if (fd == dirfd(d)) | |
236 | continue; | |
237 | ||
238 | if (fd_in_set(fd, except, n_except)) | |
239 | continue; | |
240 | ||
241 | if (close_nointr(fd) < 0) { | |
242 | /* Valgrind has its own FD and doesn't want to have it closed */ | |
243 | if (errno != EBADF && r == 0) | |
244 | r = -errno; | |
245 | } | |
246 | } | |
247 | ||
248 | return r; | |
249 | } | |
250 | ||
251 | int same_fd(int a, int b) { | |
252 | struct stat sta, stb; | |
253 | pid_t pid; | |
254 | int r, fa, fb; | |
255 | ||
256 | assert(a >= 0); | |
257 | assert(b >= 0); | |
258 | ||
259 | /* Compares two file descriptors. Note that semantics are | |
260 | * quite different depending on whether we have kcmp() or we | |
261 | * don't. If we have kcmp() this will only return true for | |
262 | * dup()ed file descriptors, but not otherwise. If we don't | |
263 | * have kcmp() this will also return true for two fds of the same | |
264 | * file, created by separate open() calls. Since we use this | |
265 | * call mostly for filtering out duplicates in the fd store | |
266 | * this difference hopefully doesn't matter too much. */ | |
267 | ||
268 | if (a == b) | |
269 | return true; | |
270 | ||
271 | /* Try to use kcmp() if we have it. */ | |
272 | pid = getpid(); | |
273 | r = kcmp(pid, pid, KCMP_FILE, a, b); | |
274 | if (r == 0) | |
275 | return true; | |
276 | if (r > 0) | |
277 | return false; | |
278 | if (errno != ENOSYS) | |
279 | return -errno; | |
280 | ||
281 | /* We don't have kcmp(), use fstat() instead. */ | |
282 | if (fstat(a, &sta) < 0) | |
283 | return -errno; | |
284 | ||
285 | if (fstat(b, &stb) < 0) | |
286 | return -errno; | |
287 | ||
288 | if ((sta.st_mode & S_IFMT) != (stb.st_mode & S_IFMT)) | |
289 | return false; | |
290 | ||
291 | /* We consider all device fds different, since two device fds | |
292 | * might refer to quite different device contexts even though | |
293 | * they share the same inode and backing dev_t. */ | |
294 | ||
295 | if (S_ISCHR(sta.st_mode) || S_ISBLK(sta.st_mode)) | |
296 | return false; | |
297 | ||
298 | if (sta.st_dev != stb.st_dev || sta.st_ino != stb.st_ino) | |
299 | return false; | |
300 | ||
301 | /* The fds refer to the same inode on disk, let's also check | |
302 | * if they have the same fd flags. This is useful to | |
303 | * distinguish the read and write side of a pipe created with | |
304 | * pipe(). */ | |
305 | fa = fcntl(a, F_GETFL); | |
306 | if (fa < 0) | |
307 | return -errno; | |
308 | ||
309 | fb = fcntl(b, F_GETFL); | |
310 | if (fb < 0) | |
311 | return -errno; | |
312 | ||
313 | return fa == fb; | |
314 | } | |
315 | ||
316 | void cmsg_close_all(struct msghdr *mh) { | |
317 | struct cmsghdr *cmsg; | |
318 | ||
319 | assert(mh); | |
320 | ||
321 | CMSG_FOREACH(cmsg, mh) | |
322 | if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) | |
323 | close_many((int*) CMSG_DATA(cmsg), (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int)); | |
324 | } | |
4fee3975 LP |
325 | |
326 | bool fdname_is_valid(const char *s) { | |
327 | const char *p; | |
328 | ||
329 | /* Validates a name for $LISTEN_FDNAMES. We basically allow | |
330 | * everything ASCII that's not a control character. Also, as | |
331 | * special exception the ":" character is not allowed, as we | |
332 | * use that as field separator in $LISTEN_FDNAMES. | |
333 | * | |
334 | * Note that the empty string is explicitly allowed | |
335 | * here. However, we limit the length of the names to 255 | |
336 | * characters. */ | |
337 | ||
338 | if (!s) | |
339 | return false; | |
340 | ||
341 | for (p = s; *p; p++) { | |
342 | if (*p < ' ') | |
343 | return false; | |
344 | if (*p >= 127) | |
345 | return false; | |
346 | if (*p == ':') | |
347 | return false; | |
348 | } | |
349 | ||
350 | return p - s < 256; | |
351 | } |