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