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
43static int _pidfile_remove(struct pidfh *pfh, int freeit);
44
45static int
46pidfile_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
62static int
63pidfile_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
86struct pidfh *
87pidfile_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, O_WRONLY | O_CREAT | O_NONBLOCK, mode);
116	if (fd >= 0) {
117		struct flock lock;
118		lock.l_type = F_WRLCK;
119		lock.l_whence = SEEK_SET;
120		lock.l_start = 0;
121		lock.l_len = 0;
122
123		if (fcntl(fd, F_SETLK, &lock) == -1) {
124			close(fd);
125			fd = -1;
126		}
127	}
128
129	if (fd == -1) {
130		if (errno == EWOULDBLOCK && pidptr != NULL) {
131			errno = pidfile_read(pfh->pf_path, pidptr);
132			if (errno == 0)
133				errno = EEXIST;
134		}
135		free(pfh);
136		return (NULL);
137	}
138
139	ftruncate(fd, 0);
140
141	/*
142	 * Remember file information, so in pidfile_write() we are sure we write
143	 * to the proper descriptor.
144	 */
145	if (fstat(fd, &sb) == -1) {
146		error = errno;
147		unlink(pfh->pf_path);
148		close(fd);
149		free(pfh);
150		errno = error;
151		return (NULL);
152	}
153
154	pfh->pf_fd = fd;
155	pfh->pf_dev = sb.st_dev;
156	pfh->pf_ino = sb.st_ino;
157
158	return (pfh);
159}
160
161int
162pidfile_write(struct pidfh *pfh)
163{
164	char pidstr[16];
165	int error, fd;
166
167	/*
168	 * Check remembered descriptor, so we don't overwrite some other
169	 * file if pidfile was closed and descriptor reused.
170	 */
171	errno = pidfile_verify(pfh);
172	if (errno != 0) {
173		/*
174		 * Don't close descriptor, because we are not sure if it's ours.
175		 */
176		return (-1);
177	}
178	fd = pfh->pf_fd;
179
180	/*
181	 * Truncate PID file, so multiple calls of pidfile_write() are allowed.
182	 */
183	if (ftruncate(fd, 0) == -1) {
184		error = errno;
185		_pidfile_remove(pfh, 0);
186		errno = error;
187		return (-1);
188	}
189
190	snprintf(pidstr, sizeof(pidstr), "%lu", getpid());
191	if (pwrite(fd, pidstr, strlen(pidstr), 0) != (ssize_t)strlen(pidstr)) {
192		error = errno;
193		_pidfile_remove(pfh, 0);
194		errno = error;
195		return (-1);
196	}
197
198	return (0);
199}
200
201int
202pidfile_close(struct pidfh *pfh)
203{
204	int error;
205
206	error = pidfile_verify(pfh);
207	if (error != 0) {
208		errno = error;
209		return (-1);
210	}
211
212	if (close(pfh->pf_fd) == -1)
213		error = errno;
214	free(pfh);
215	if (error != 0) {
216		errno = error;
217		return (-1);
218	}
219	return (0);
220}
221
222static int
223_pidfile_remove(struct pidfh *pfh, int freeit)
224{
225	int error;
226
227	error = pidfile_verify(pfh);
228	if (error != 0) {
229		errno = error;
230		return (-1);
231	}
232
233	if (unlink(pfh->pf_path) == -1)
234		error = errno;
235	if (flock(pfh->pf_fd, LOCK_UN) == -1) {
236		if (error == 0)
237			error = errno;
238	}
239	if (close(pfh->pf_fd) == -1) {
240		if (error == 0)
241			error = errno;
242	}
243	if (freeit)
244		free(pfh);
245	else
246		pfh->pf_fd = -1;
247	if (error != 0) {
248		errno = error;
249		return (-1);
250	}
251	return (0);
252}
253
254int
255pidfile_remove(struct pidfh *pfh)
256{
257
258	return (_pidfile_remove(pfh, 1));
259}
260