1 /*-
2 * Copyright (c) 2005 Pawel Jakub Dawidek <pjd@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: head/lib/libutil/pidfile.c 255007 2013-08-28 21:10:37Z jilles $
27 */
28
29 #include <sys/param.h>
30 #include <sys/stat.h>
31
32 #include <stdio.h>
33 #include <stdlib.h>
34 #include <unistd.h>
35 #include <fcntl.h>
36 #include <string.h>
37 #include <time.h>
38 #include <err.h>
39 #include <errno.h>
40 #include <libutil.h>
41
42 struct pidfh {
43 int pf_fd;
44 char pf_path[MAXPATHLEN + 1];
45 dev_t pf_dev;
46 ino_t pf_ino;
47 };
48
49 static int _pidfile_remove(struct pidfh *pfh, int freeit);
50
51 static int
pidfile_verify(const struct pidfh * pfh)52 pidfile_verify(const struct pidfh *pfh)
53 {
54 struct stat sb;
55
56 if (pfh == NULL || pfh->pf_fd == -1)
57 return (EDOOFUS);
58 /*
59 * Check remembered descriptor.
60 */
61 if (fstat(pfh->pf_fd, &sb) == -1)
62 return (errno);
63 if (sb.st_dev != pfh->pf_dev || sb.st_ino != pfh->pf_ino)
64 return (EDOOFUS);
65 return (0);
66 }
67
68 static int
pidfile_read(const char * path,pid_t * pidptr)69 pidfile_read(const char *path, pid_t *pidptr)
70 {
71 char buf[16], *endptr;
72 int error, fd, i;
73
74 fd = open(path, O_RDONLY | O_CLOEXEC);
75 if (fd == -1)
76 return (errno);
77
78 i = read(fd, buf, sizeof(buf) - 1);
79 error = errno; /* Remember errno in case close() wants to change it. */
80 close(fd);
81 if (i == -1)
82 return (error);
83 else if (i == 0)
84 return (EAGAIN);
85 buf[i] = '\0';
86
87 *pidptr = strtol(buf, &endptr, 10);
88 if (endptr != &buf[i])
89 return (EINVAL);
90
91 return (0);
92 }
93
94 struct pidfh *
pidfile_open(const char * path,mode_t mode,pid_t * pidptr)95 pidfile_open(const char *path, mode_t mode, pid_t *pidptr)
96 {
97 struct pidfh *pfh;
98 struct stat sb;
99 int error, fd, len, count;
100 struct timespec rqtp;
101
102 pfh = malloc(sizeof(*pfh));
103 if (pfh == NULL)
104 return (NULL);
105
106 if (path == NULL)
107 len = snprintf(pfh->pf_path, sizeof(pfh->pf_path),
108 "/var/run/%s.pid", getprogname());
109 else
110 len = snprintf(pfh->pf_path, sizeof(pfh->pf_path),
111 "%s", path);
112 if (len >= (int)sizeof(pfh->pf_path)) {
113 free(pfh);
114 errno = ENAMETOOLONG;
115 return (NULL);
116 }
117
118 /*
119 * Open the PID file and obtain exclusive lock.
120 * We truncate PID file here only to remove old PID immediatelly,
121 * PID file will be truncated again in pidfile_write(), so
122 * pidfile_write() can be called multiple times.
123 */
124 fd = flopen(pfh->pf_path,
125 O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC | O_NONBLOCK, mode);
126 if (fd == -1) {
127 if (errno == EWOULDBLOCK) {
128 if (pidptr == NULL) {
129 errno = EEXIST;
130 } else {
131 count = 20;
132 rqtp.tv_sec = 0;
133 rqtp.tv_nsec = 5000000;
134 for (;;) {
135 errno = pidfile_read(pfh->pf_path,
136 pidptr);
137 if (errno != EAGAIN || --count == 0)
138 break;
139 nanosleep(&rqtp, 0);
140 }
141 if (errno == EAGAIN)
142 *pidptr = -1;
143 if (errno == 0 || errno == EAGAIN)
144 errno = EEXIST;
145 }
146 }
147 free(pfh);
148 return (NULL);
149 }
150
151 /*
152 * Remember file information, so in pidfile_write() we are sure we write
153 * to the proper descriptor.
154 */
155 if (fstat(fd, &sb) == -1) {
156 error = errno;
157 unlink(pfh->pf_path);
158 close(fd);
159 free(pfh);
160 errno = error;
161 return (NULL);
162 }
163
164 pfh->pf_fd = fd;
165 pfh->pf_dev = sb.st_dev;
166 pfh->pf_ino = sb.st_ino;
167
168 return (pfh);
169 }
170
171 int
pidfile_write(struct pidfh * pfh)172 pidfile_write(struct pidfh *pfh)
173 {
174 char pidstr[16];
175 int error, fd;
176
177 /*
178 * Check remembered descriptor, so we don't overwrite some other
179 * file if pidfile was closed and descriptor reused.
180 */
181 errno = pidfile_verify(pfh);
182 if (errno != 0) {
183 /*
184 * Don't close descriptor, because we are not sure if it's ours.
185 */
186 return (-1);
187 }
188 fd = pfh->pf_fd;
189
190 /*
191 * Truncate PID file, so multiple calls of pidfile_write() are allowed.
192 */
193 if (ftruncate(fd, 0) == -1) {
194 error = errno;
195 _pidfile_remove(pfh, 0);
196 errno = error;
197 return (-1);
198 }
199
200 snprintf(pidstr, sizeof(pidstr), "%u", getpid());
201 if (pwrite(fd, pidstr, strlen(pidstr), 0) != (ssize_t)strlen(pidstr)) {
202 error = errno;
203 _pidfile_remove(pfh, 0);
204 errno = error;
205 return (-1);
206 }
207
208 return (0);
209 }
210
211 int
pidfile_close(struct pidfh * pfh)212 pidfile_close(struct pidfh *pfh)
213 {
214 int error;
215
216 error = pidfile_verify(pfh);
217 if (error != 0) {
218 errno = error;
219 return (-1);
220 }
221
222 if (close(pfh->pf_fd) == -1)
223 error = errno;
224 free(pfh);
225 if (error != 0) {
226 errno = error;
227 return (-1);
228 }
229 return (0);
230 }
231
232 static int
_pidfile_remove(struct pidfh * pfh,int freeit)233 _pidfile_remove(struct pidfh *pfh, int freeit)
234 {
235 int error;
236
237 error = pidfile_verify(pfh);
238 if (error != 0) {
239 errno = error;
240 return (-1);
241 }
242
243 if (unlink(pfh->pf_path) == -1)
244 error = errno;
245 if (close(pfh->pf_fd) == -1) {
246 if (error == 0)
247 error = errno;
248 }
249 if (freeit)
250 free(pfh);
251 else
252 pfh->pf_fd = -1;
253 if (error != 0) {
254 errno = error;
255 return (-1);
256 }
257 return (0);
258 }
259
260 int
pidfile_remove(struct pidfh * pfh)261 pidfile_remove(struct pidfh *pfh)
262 {
263
264 return (_pidfile_remove(pfh, 1));
265 }
266
267 int
pidfile_fileno(const struct pidfh * pfh)268 pidfile_fileno(const struct pidfh *pfh)
269 {
270
271 if (pfh == NULL || pfh->pf_fd == -1) {
272 errno = EDOOFUS;
273 return (-1);
274 }
275 return (pfh->pf_fd);
276 }
277