summaryrefslogtreecommitdiffstats
path: root/lib/libutil/pidfile.c
blob: 6b99936f7aa292c88749a29dc69a6bda7faee705 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
/*-
 * Copyright (c) 2005 Pawel Jakub Dawidek <pjd@FreeBSD.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <sys/param.h>
#include <sys/file.h>
#include <sys/stat.h>

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <time.h>
#include <err.h>
#include <errno.h>
#include <libutil.h>

static int _pidfile_remove(struct pidfh *pfh, int freeit);

static int
pidfile_verify(struct pidfh *pfh)
{
	struct stat sb;

	if (pfh == NULL || pfh->pf_fd == -1)
		return (EDOOFUS);
	/*
	 * Check remembered descriptor.
	 */
	if (fstat(pfh->pf_fd, &sb) == -1)
		return (errno);
	if (sb.st_dev != pfh->pf_dev || sb.st_ino != pfh->pf_ino)
		return (EDOOFUS);
	return (0);
}

static int
pidfile_read(const char *path, pid_t *pidptr)
{
	char buf[16], *endptr;
	int error, fd, i;

	fd = open(path, O_RDONLY);
	if (fd == -1)
		return (errno);

	i = read(fd, buf, sizeof(buf) - 1);
	error = errno;	/* Remember errno in case close() wants to change it. */
	close(fd);
	if (i == -1)
		return (error);
	else if (i == 0)
		return (EAGAIN);
	buf[i] = '\0';

	*pidptr = strtol(buf, &endptr, 10);
	if (endptr != &buf[i])
		return (EINVAL);

	return (0);
}

struct pidfh *
pidfile_open(const char *path, mode_t mode, pid_t *pidptr)
{
	struct pidfh *pfh;
	struct stat sb;
	int error, fd, len, count;
	struct timespec rqtp;

	pfh = malloc(sizeof(*pfh));
	if (pfh == NULL)
		return (NULL);

	if (path == NULL)
		len = snprintf(pfh->pf_path, sizeof(pfh->pf_path),
		    "/var/run/%s.pid", getprogname());
	else
		len = snprintf(pfh->pf_path, sizeof(pfh->pf_path),
		    "%s", path);
	if (len >= (int)sizeof(pfh->pf_path)) {
		free(pfh);
		errno = ENAMETOOLONG;
		return (NULL);
	}

	/*
	 * Open the PID file and obtain exclusive lock.
	 * We truncate PID file here only to remove old PID immediatelly,
	 * PID file will be truncated again in pidfile_write(), so
	 * pidfile_write() can be called multiple times.
	 */
	fd = flopen(pfh->pf_path,
	    O_WRONLY | O_CREAT | O_TRUNC | O_NONBLOCK, mode);
	if (fd == -1) {
		count = 0;
		rqtp.tv_sec = 0;
		rqtp.tv_nsec = 5000000;
		if (errno == EWOULDBLOCK && pidptr != NULL) {
		again:
			errno = pidfile_read(pfh->pf_path, pidptr);
			if (errno == 0)
				errno = EEXIST;
			else if (errno == EAGAIN) {
				if (++count <= 3) {
					nanosleep(&rqtp, 0);
					goto again;
				}
			}
		}
		free(pfh);
		return (NULL);
	}
	/*
	 * Remember file information, so in pidfile_write() we are sure we write
	 * to the proper descriptor.
	 */
	if (fstat(fd, &sb) == -1) {
		error = errno;
		unlink(pfh->pf_path);
		close(fd);
		free(pfh);
		errno = error;
		return (NULL);
	}

	pfh->pf_fd = fd;
	pfh->pf_dev = sb.st_dev;
	pfh->pf_ino = sb.st_ino;

	return (pfh);
}

int
pidfile_write(struct pidfh *pfh)
{
	char pidstr[16];
	int error, fd;

	/*
	 * Check remembered descriptor, so we don't overwrite some other
	 * file if pidfile was closed and descriptor reused.
	 */
	errno = pidfile_verify(pfh);
	if (errno != 0) {
		/*
		 * Don't close descriptor, because we are not sure if it's ours.
		 */
		return (-1);
	}
	fd = pfh->pf_fd;

	/*
	 * Truncate PID file, so multiple calls of pidfile_write() are allowed.
	 */
	if (ftruncate(fd, 0) == -1) {
		error = errno;
		_pidfile_remove(pfh, 0);
		errno = error;
		return (-1);
	}

	snprintf(pidstr, sizeof(pidstr), "%u", getpid());
	if (pwrite(fd, pidstr, strlen(pidstr), 0) != (ssize_t)strlen(pidstr)) {
		error = errno;
		_pidfile_remove(pfh, 0);
		errno = error;
		return (-1);
	}

	return (0);
}

int
pidfile_close(struct pidfh *pfh)
{
	int error;

	error = pidfile_verify(pfh);
	if (error != 0) {
		errno = error;
		return (-1);
	}

	if (close(pfh->pf_fd) == -1)
		error = errno;
	free(pfh);
	if (error != 0) {
		errno = error;
		return (-1);
	}
	return (0);
}

static int
_pidfile_remove(struct pidfh *pfh, int freeit)
{
	int error;

	error = pidfile_verify(pfh);
	if (error != 0) {
		errno = error;
		return (-1);
	}

	if (unlink(pfh->pf_path) == -1)
		error = errno;
	if (close(pfh->pf_fd) == -1) {
		if (error == 0)
			error = errno;
	}
	if (freeit)
		free(pfh);
	else
		pfh->pf_fd = -1;
	if (error != 0) {
		errno = error;
		return (-1);
	}
	return (0);
}

int
pidfile_remove(struct pidfh *pfh)
{

	return (_pidfile_remove(pfh, 1));
}
OpenPOWER on IntegriCloud