xref: /haiku/src/libs/util/pidfile.c (revision 89755088d790ff4fe36f8aa77dacb2bd15507108)
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 <libutil.h>
42 
43 static int _pidfile_remove(struct pidfh *pfh, int freeit);
44 
45 static int
46 pidfile_verify(struct pidfh *pfh)
47 {
48 	struct stat sb;
49 
50 	if (pfh == NULL || pfh->pf_fd == -1)
51 		return (EDOOFUS);
52 	/*
53 	 * Check remembered descriptor.
54 	 */
55 	if (fstat(pfh->pf_fd, &sb) == -1)
56 		return (errno);
57 	if (sb.st_dev != pfh->pf_dev || sb.st_ino != pfh->pf_ino)
58 		return (EDOOFUS);
59 	return (0);
60 }
61 
62 static int
63 pidfile_read(const char *path, pid_t *pidptr)
64 {
65 	char buf[16], *endptr;
66 	int error, fd, i;
67 
68 	fd = open(path, O_RDONLY);
69 	if (fd == -1)
70 		return (errno);
71 
72 	i = read(fd, buf, sizeof(buf) - 1);
73 	error = errno;	/* Remember errno in case close() wants to change it. */
74 	close(fd);
75 	if (i == -1)
76 		return (error);
77 	buf[i] = '\0';
78 
79 	*pidptr = strtol(buf, &endptr, 10);
80 	if (endptr != &buf[i])
81 		return (EINVAL);
82 
83 	return (0);
84 }
85 
86 struct pidfh *
87 pidfile_open(const char *path, mode_t mode, pid_t *pidptr)
88 {
89 	struct pidfh *pfh;
90 	struct stat sb;
91 	int error, fd;
92 
93 	pfh = malloc(sizeof(*pfh));
94 	if (pfh == NULL)
95 		return (NULL);
96 
97 	if (path == NULL) {
98 		snprintf(pfh->pf_path, sizeof(pfh->pf_path), "/var/run/%s.pid",
99 		    getprogname());
100 	} else {
101 		strlcpy(pfh->pf_path, path, sizeof(pfh->pf_path));
102 	}
103 	if (strlen(pfh->pf_path) == sizeof(pfh->pf_path) - 1) {
104 		free(pfh);
105 		errno = ENAMETOOLONG;
106 		return (NULL);
107 	}
108 
109 	/*
110 	 * Open the PID file and obtain exclusive lock.
111 	 * We truncate PID file here only to remove old PID immediatelly,
112 	 * PID file will be truncated again in pidfile_write(), so
113 	 * pidfile_write() can be called multiple times.
114 	 */
115 	fd = open(pfh->pf_path,
116 	    O_WRONLY | O_CREAT | O_EXLOCK | O_TRUNC | O_NONBLOCK, mode);
117 	if (fd == -1) {
118 		if (errno == EWOULDBLOCK && pidptr != NULL) {
119 			errno = pidfile_read(pfh->pf_path, pidptr);
120 			if (errno == 0)
121 				errno = EEXIST;
122 		}
123 		free(pfh);
124 		return (NULL);
125 	}
126 	/*
127 	 * Remember file information, so in pidfile_write() we are sure we write
128 	 * to the proper descriptor.
129 	 */
130 	if (fstat(fd, &sb) == -1) {
131 		error = errno;
132 		unlink(pfh->pf_path);
133 		close(fd);
134 		free(pfh);
135 		errno = error;
136 		return (NULL);
137 	}
138 
139 	pfh->pf_fd = fd;
140 	pfh->pf_dev = sb.st_dev;
141 	pfh->pf_ino = sb.st_ino;
142 
143 	return (pfh);
144 }
145 
146 int
147 pidfile_write(struct pidfh *pfh)
148 {
149 	char pidstr[16];
150 	int error, fd;
151 
152 	/*
153 	 * Check remembered descriptor, so we don't overwrite some other
154 	 * file if pidfile was closed and descriptor reused.
155 	 */
156 	errno = pidfile_verify(pfh);
157 	if (errno != 0) {
158 		/*
159 		 * Don't close descriptor, because we are not sure if it's ours.
160 		 */
161 		return (-1);
162 	}
163 	fd = pfh->pf_fd;
164 
165 	/*
166 	 * Truncate PID file, so multiple calls of pidfile_write() are allowed.
167 	 */
168 	if (ftruncate(fd, 0) == -1) {
169 		error = errno;
170 		_pidfile_remove(pfh, 0);
171 		errno = error;
172 		return (-1);
173 	}
174 
175 	snprintf(pidstr, sizeof(pidstr), "%lu", getpid());
176 	if (pwrite(fd, pidstr, strlen(pidstr), 0) != (ssize_t)strlen(pidstr)) {
177 		error = errno;
178 		_pidfile_remove(pfh, 0);
179 		errno = error;
180 		return (-1);
181 	}
182 
183 	return (0);
184 }
185 
186 int
187 pidfile_close(struct pidfh *pfh)
188 {
189 	int error;
190 
191 	error = pidfile_verify(pfh);
192 	if (error != 0) {
193 		errno = error;
194 		return (-1);
195 	}
196 
197 	if (close(pfh->pf_fd) == -1)
198 		error = errno;
199 	free(pfh);
200 	if (error != 0) {
201 		errno = error;
202 		return (-1);
203 	}
204 	return (0);
205 }
206 
207 static int
208 _pidfile_remove(struct pidfh *pfh, int freeit)
209 {
210 	int error;
211 
212 	error = pidfile_verify(pfh);
213 	if (error != 0) {
214 		errno = error;
215 		return (-1);
216 	}
217 
218 	if (unlink(pfh->pf_path) == -1)
219 		error = errno;
220 	if (flock(pfh->pf_fd, LOCK_UN) == -1) {
221 		if (error == 0)
222 			error = errno;
223 	}
224 	if (close(pfh->pf_fd) == -1) {
225 		if (error == 0)
226 			error = errno;
227 	}
228 	if (freeit)
229 		free(pfh);
230 	else
231 		pfh->pf_fd = -1;
232 	if (error != 0) {
233 		errno = error;
234 		return (-1);
235 	}
236 	return (0);
237 }
238 
239 int
240 pidfile_remove(struct pidfh *pfh)
241 {
242 
243 	return (_pidfile_remove(pfh, 1));
244 }
245