1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2005 Pawel Jakub Dawidek <[email protected]>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31
32 #include <sys/param.h>
33 #include <sys/capsicum.h>
34 #include <sys/file.h>
35 #include <sys/stat.h>
36
37 #include <err.h>
38 #include <errno.h>
39 #include <fcntl.h>
40 #include <libgen.h>
41 #include <libutil.h>
42 #include <stdio.h>
43 #include <stdlib.h>
44 #include <string.h>
45 #include <time.h>
46 #include <unistd.h>
47
48 struct pidfh {
49 int pf_dirfd;
50 int pf_fd;
51 char pf_dir[MAXPATHLEN + 1];
52 char pf_filename[MAXPATHLEN + 1];
53 dev_t pf_dev;
54 ino_t pf_ino;
55 };
56
57 static int _pidfile_remove(struct pidfh *pfh, int freeit);
58
59 static int
pidfile_verify(const struct pidfh * pfh)60 pidfile_verify(const struct pidfh *pfh)
61 {
62 struct stat sb;
63
64 if (pfh == NULL || pfh->pf_fd == -1)
65 return (EDOOFUS);
66 /*
67 * Check remembered descriptor.
68 */
69 if (fstat(pfh->pf_fd, &sb) == -1)
70 return (errno);
71 if (sb.st_dev != pfh->pf_dev || sb.st_ino != pfh->pf_ino)
72 return (EDOOFUS);
73 return (0);
74 }
75
76 static int
pidfile_read(int dirfd,const char * filename,pid_t * pidptr)77 pidfile_read(int dirfd, const char *filename, pid_t *pidptr)
78 {
79 char buf[16], *endptr;
80 int error, fd, i;
81
82 fd = openat(dirfd, filename, O_RDONLY | O_CLOEXEC);
83 if (fd == -1)
84 return (errno);
85
86 i = read(fd, buf, sizeof(buf) - 1);
87 error = errno; /* Remember errno in case close() wants to change it. */
88 close(fd);
89 if (i == -1)
90 return (error);
91 else if (i == 0)
92 return (EAGAIN);
93 buf[i] = '\0';
94
95 *pidptr = strtol(buf, &endptr, 10);
96 if (endptr != &buf[i])
97 return (EINVAL);
98
99 return (0);
100 }
101
102 struct pidfh *
pidfile_open(const char * pathp,mode_t mode,pid_t * pidptr)103 pidfile_open(const char *pathp, mode_t mode, pid_t *pidptr)
104 {
105 char path[MAXPATHLEN];
106 struct pidfh *pfh;
107 struct stat sb;
108 int error, fd, dirfd, dirlen, filenamelen, count;
109 struct timespec rqtp;
110 cap_rights_t caprights;
111
112 pfh = malloc(sizeof(*pfh));
113 if (pfh == NULL)
114 return (NULL);
115
116 if (pathp == NULL) {
117 dirlen = snprintf(pfh->pf_dir, sizeof(pfh->pf_dir),
118 "/var/run/");
119 filenamelen = snprintf(pfh->pf_filename,
120 sizeof(pfh->pf_filename), "%s.pid", getprogname());
121 } else {
122 if (strlcpy(path, pathp, sizeof(path)) >= sizeof(path)) {
123 free(pfh);
124 errno = ENAMETOOLONG;
125 return (NULL);
126 }
127 dirlen = strlcpy(pfh->pf_dir, dirname(path),
128 sizeof(pfh->pf_dir));
129 (void)strlcpy(path, pathp, sizeof(path));
130 filenamelen = strlcpy(pfh->pf_filename, basename(path),
131 sizeof(pfh->pf_filename));
132 }
133
134 if (dirlen >= (int)sizeof(pfh->pf_dir) ||
135 filenamelen >= (int)sizeof(pfh->pf_filename)) {
136 free(pfh);
137 errno = ENAMETOOLONG;
138 return (NULL);
139 }
140
141 dirfd = open(pfh->pf_dir, O_CLOEXEC | O_DIRECTORY | O_NONBLOCK);
142 if (dirfd == -1) {
143 error = errno;
144 free(pfh);
145 errno = error;
146 return (NULL);
147 }
148
149 /*
150 * Open the PID file and obtain exclusive lock.
151 * We truncate PID file here only to remove old PID immediately,
152 * PID file will be truncated again in pidfile_write(), so
153 * pidfile_write() can be called multiple times.
154 */
155 fd = flopenat(dirfd, pfh->pf_filename,
156 O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC | O_NONBLOCK, mode);
157 if (fd == -1) {
158 if (errno == EWOULDBLOCK) {
159 if (pidptr == NULL) {
160 errno = EEXIST;
161 } else {
162 count = 20;
163 rqtp.tv_sec = 0;
164 rqtp.tv_nsec = 5000000;
165 for (;;) {
166 errno = pidfile_read(dirfd,
167 pfh->pf_filename, pidptr);
168 if (errno != EAGAIN || --count == 0)
169 break;
170 nanosleep(&rqtp, 0);
171 }
172 if (errno == EAGAIN)
173 *pidptr = -1;
174 if (errno == 0 || errno == EAGAIN)
175 errno = EEXIST;
176 }
177 }
178 error = errno;
179 close(dirfd);
180 free(pfh);
181 errno = error;
182 return (NULL);
183 }
184
185 /*
186 * Remember file information, so in pidfile_write() we are sure we write
187 * to the proper descriptor.
188 */
189 if (fstat(fd, &sb) == -1) {
190 goto failed;
191 }
192
193 if (cap_rights_limit(dirfd,
194 cap_rights_init(&caprights, CAP_UNLINKAT)) < 0 && errno != ENOSYS) {
195 goto failed;
196 }
197
198 if (cap_rights_limit(fd, cap_rights_init(&caprights, CAP_PWRITE,
199 CAP_FSTAT, CAP_FTRUNCATE, CAP_EVENT)) < 0 &&
200 errno != ENOSYS) {
201 goto failed;
202 }
203
204 pfh->pf_dirfd = dirfd;
205 pfh->pf_fd = fd;
206 pfh->pf_dev = sb.st_dev;
207 pfh->pf_ino = sb.st_ino;
208
209 return (pfh);
210
211 failed:
212 error = errno;
213 unlinkat(dirfd, pfh->pf_filename, 0);
214 close(dirfd);
215 close(fd);
216 free(pfh);
217 errno = error;
218 return (NULL);
219 }
220
221 int
pidfile_write(struct pidfh * pfh)222 pidfile_write(struct pidfh *pfh)
223 {
224 char pidstr[16];
225 int error, fd;
226
227 /*
228 * Check remembered descriptor, so we don't overwrite some other
229 * file if pidfile was closed and descriptor reused.
230 */
231 errno = pidfile_verify(pfh);
232 if (errno != 0) {
233 /*
234 * Don't close descriptor, because we are not sure if it's ours.
235 */
236 return (-1);
237 }
238 fd = pfh->pf_fd;
239
240 /*
241 * Truncate PID file, so multiple calls of pidfile_write() are allowed.
242 */
243 if (ftruncate(fd, 0) == -1) {
244 error = errno;
245 _pidfile_remove(pfh, 0);
246 errno = error;
247 return (-1);
248 }
249
250 snprintf(pidstr, sizeof(pidstr), "%u", getpid());
251 if (pwrite(fd, pidstr, strlen(pidstr), 0) != (ssize_t)strlen(pidstr)) {
252 error = errno;
253 _pidfile_remove(pfh, 0);
254 errno = error;
255 return (-1);
256 }
257
258 return (0);
259 }
260
261 int
pidfile_close(struct pidfh * pfh)262 pidfile_close(struct pidfh *pfh)
263 {
264 int error;
265
266 error = pidfile_verify(pfh);
267 if (error != 0) {
268 errno = error;
269 return (-1);
270 }
271
272 if (close(pfh->pf_fd) == -1)
273 error = errno;
274 if (close(pfh->pf_dirfd) == -1 && error == 0)
275 error = errno;
276
277 free(pfh);
278 if (error != 0) {
279 errno = error;
280 return (-1);
281 }
282 return (0);
283 }
284
285 static int
_pidfile_remove(struct pidfh * pfh,int freeit)286 _pidfile_remove(struct pidfh *pfh, int freeit)
287 {
288 int error;
289
290 error = pidfile_verify(pfh);
291 if (error != 0) {
292 errno = error;
293 return (-1);
294 }
295
296 if (funlinkat(pfh->pf_dirfd, pfh->pf_filename, pfh->pf_fd, 0) == -1) {
297 if (errno == EDEADLK)
298 return (-1);
299 error = errno;
300 }
301 if (close(pfh->pf_fd) == -1 && error == 0)
302 error = errno;
303 if (close(pfh->pf_dirfd) == -1 && error == 0)
304 error = errno;
305 if (freeit)
306 free(pfh);
307 else
308 pfh->pf_fd = -1;
309 if (error != 0) {
310 errno = error;
311 return (-1);
312 }
313 return (0);
314 }
315
316 int
pidfile_remove(struct pidfh * pfh)317 pidfile_remove(struct pidfh *pfh)
318 {
319
320 return (_pidfile_remove(pfh, 1));
321 }
322
323 int
pidfile_fileno(const struct pidfh * pfh)324 pidfile_fileno(const struct pidfh *pfh)
325 {
326
327 if (pfh == NULL || pfh->pf_fd == -1) {
328 errno = EDOOFUS;
329 return (-1);
330 }
331 return (pfh->pf_fd);
332 }
333