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
44static int _pidfile_remove(struct pidfh *pfh, int freeit);
45
46static int
47pidfile_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
63static int
64pidfile_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
87struct pidfh *
88pidfile_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
162int
163pidfile_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
202int
203pidfile_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
223static int
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
255int
256pidfile_remove(struct pidfh *pfh)
257{
258
259	return (_pidfile_remove(pfh, 1));
260}
261