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
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD: src/lib/libutil/pidfile.c,v 1.3 2006/06/23 01:42:03 brian Exp $");
29
30 #include <sys/param.h>
31 #include <sys/file.h>
32 #include <sys/stat.h>
33
34 #include <stdio.h>
35 #include <stdlib.h>
36 #include <unistd.h>
37 #include <fcntl.h>
38 #include <string.h>
39 #include <err.h>
40 #include <errno.h>
41 #include <inttypes.h>
42 #include <libutil.h>
43
44 static int _pidfile_remove(struct pidfh *pfh, int freeit);
45
46 static int
pidfile_verify(struct pidfh * pfh)47 pidfile_verify(struct pidfh *pfh)
48 {
49 struct stat sb;
50
51 if (pfh == NULL || pfh->pf_fd == -1)
52 return (EDOOFUS);
53 /*
54 * Check remembered descriptor.
55 */
56 if (fstat(pfh->pf_fd, &sb) == -1)
57 return (errno);
58 if (sb.st_dev != pfh->pf_dev || sb.st_ino != pfh->pf_ino)
59 return (EDOOFUS);
60 return (0);
61 }
62
63 static int
pidfile_read(const char * path,pid_t * pidptr)64 pidfile_read(const char *path, pid_t *pidptr)
65 {
66 char buf[16], *endptr;
67 int error, fd, i;
68
69 fd = open(path, O_RDONLY);
70 if (fd == -1)
71 return (errno);
72
73 i = read(fd, buf, sizeof(buf) - 1);
74 error = errno; /* Remember errno in case close() wants to change it. */
75 close(fd);
76 if (i == -1)
77 return (error);
78 buf[i] = '\0';
79
80 *pidptr = strtol(buf, &endptr, 10);
81 if (endptr != &buf[i])
82 return (EINVAL);
83
84 return (0);
85 }
86
87 struct pidfh *
pidfile_open(const char * path,mode_t mode,pid_t * pidptr)88 pidfile_open(const char *path, mode_t mode, pid_t *pidptr)
89 {
90 struct pidfh *pfh;
91 struct stat sb;
92 int error, fd;
93
94 pfh = malloc(sizeof(*pfh));
95 if (pfh == NULL)
96 return (NULL);
97
98 if (path == NULL) {
99 snprintf(pfh->pf_path, sizeof(pfh->pf_path), "/var/run/%s.pid",
100 getprogname());
101 } else {
102 strlcpy(pfh->pf_path, path, sizeof(pfh->pf_path));
103 }
104 if (strlen(pfh->pf_path) == sizeof(pfh->pf_path) - 1) {
105 free(pfh);
106 errno = ENAMETOOLONG;
107 return (NULL);
108 }
109
110 /*
111 * Open the PID file and obtain exclusive lock.
112 * We truncate PID file here only to remove old PID immediatelly,
113 * PID file will be truncated again in pidfile_write(), so
114 * pidfile_write() can be called multiple times.
115 */
116 fd = open(pfh->pf_path, O_WRONLY | O_CREAT | O_NONBLOCK, mode);
117 if (fd >= 0) {
118 struct flock lock;
119 lock.l_type = F_WRLCK;
120 lock.l_whence = SEEK_SET;
121 lock.l_start = 0;
122 lock.l_len = 0;
123
124 if (fcntl(fd, F_SETLK, &lock) == -1) {
125 close(fd);
126 fd = -1;
127 }
128 }
129
130 if (fd == -1) {
131 if (errno == EWOULDBLOCK && pidptr != NULL) {
132 errno = pidfile_read(pfh->pf_path, pidptr);
133 if (errno == 0)
134 errno = EEXIST;
135 }
136 free(pfh);
137 return (NULL);
138 }
139
140 ftruncate(fd, 0);
141
142 /*
143 * Remember file information, so in pidfile_write() we are sure we write
144 * to the proper descriptor.
145 */
146 if (fstat(fd, &sb) == -1) {
147 error = errno;
148 unlink(pfh->pf_path);
149 close(fd);
150 free(pfh);
151 errno = error;
152 return (NULL);
153 }
154
155 pfh->pf_fd = fd;
156 pfh->pf_dev = sb.st_dev;
157 pfh->pf_ino = sb.st_ino;
158
159 return (pfh);
160 }
161
162 int
pidfile_write(struct pidfh * pfh)163 pidfile_write(struct pidfh *pfh)
164 {
165 char pidstr[16];
166 int error, fd;
167
168 /*
169 * Check remembered descriptor, so we don't overwrite some other
170 * file if pidfile was closed and descriptor reused.
171 */
172 errno = pidfile_verify(pfh);
173 if (errno != 0) {
174 /*
175 * Don't close descriptor, because we are not sure if it's ours.
176 */
177 return (-1);
178 }
179 fd = pfh->pf_fd;
180
181 /*
182 * Truncate PID file, so multiple calls of pidfile_write() are allowed.
183 */
184 if (ftruncate(fd, 0) == -1) {
185 error = errno;
186 _pidfile_remove(pfh, 0);
187 errno = error;
188 return (-1);
189 }
190
191 snprintf(pidstr, sizeof(pidstr), "%" PRIu32, getpid());
192 if (pwrite(fd, pidstr, strlen(pidstr), 0) != (ssize_t)strlen(pidstr)) {
193 error = errno;
194 _pidfile_remove(pfh, 0);
195 errno = error;
196 return (-1);
197 }
198
199 return (0);
200 }
201
202 int
pidfile_close(struct pidfh * pfh)203 pidfile_close(struct pidfh *pfh)
204 {
205 int error;
206
207 error = pidfile_verify(pfh);
208 if (error != 0) {
209 errno = error;
210 return (-1);
211 }
212
213 if (close(pfh->pf_fd) == -1)
214 error = errno;
215 free(pfh);
216 if (error != 0) {
217 errno = error;
218 return (-1);
219 }
220 return (0);
221 }
222
223 static int
_pidfile_remove(struct pidfh * pfh,int freeit)224 _pidfile_remove(struct pidfh *pfh, int freeit)
225 {
226 int error;
227
228 error = pidfile_verify(pfh);
229 if (error != 0) {
230 errno = error;
231 return (-1);
232 }
233
234 if (unlink(pfh->pf_path) == -1)
235 error = errno;
236 if (flock(pfh->pf_fd, LOCK_UN) == -1) {
237 if (error == 0)
238 error = errno;
239 }
240 if (close(pfh->pf_fd) == -1) {
241 if (error == 0)
242 error = errno;
243 }
244 if (freeit)
245 free(pfh);
246 else
247 pfh->pf_fd = -1;
248 if (error != 0) {
249 errno = error;
250 return (-1);
251 }
252 return (0);
253 }
254
255 int
pidfile_remove(struct pidfh * pfh)256 pidfile_remove(struct pidfh *pfh)
257 {
258
259 return (_pidfile_remove(pfh, 1));
260 }
261