aboutsummaryrefslogtreecommitdiffstats
path: root/cmd/zed/zed_log.c
blob: 948dad52adb81aec9267a2ec08e439c89cc59fae (plain) (blame)
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
255
256
/*
 * This file is part of the ZFS Event Daemon (ZED).
 *
 * Developed at Lawrence Livermore National Laboratory (LLNL-CODE-403049).
 * Copyright (C) 2013-2014 Lawrence Livermore National Security, LLC.
 * Refer to the ZoL git commit log for authoritative copyright attribution.
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License Version 1.0 (CDDL-1.0).
 * You can obtain a copy of the license from the top-level file
 * "OPENSOLARIS.LICENSE" or at <http://opensource.org/licenses/CDDL-1.0>.
 * You may not use this file except in compliance with the license.
 */

#include <assert.h>
#include <errno.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <syslog.h>
#include <unistd.h>
#include "zed_log.h"

#define	ZED_LOG_MAX_LOG_LEN	1024

static struct {
	unsigned do_stderr:1;
	unsigned do_syslog:1;
	const char *identity;
	int priority;
	int pipe_fd[2];
} _ctx;

/*
 * Initialize the logging subsystem.
 */
void
zed_log_init(const char *identity)
{
	if (identity) {
		const char *p = strrchr(identity, '/');
		_ctx.identity = (p != NULL) ? p + 1 : identity;
	} else {
		_ctx.identity = NULL;
	}
	_ctx.pipe_fd[0] = -1;
	_ctx.pipe_fd[1] = -1;
}

/*
 * Shutdown the logging subsystem.
 */
void
zed_log_fini(void)
{
	zed_log_stderr_close();
	zed_log_syslog_close();
}

/*
 * Create pipe for communicating daemonization status between the parent and
 * child processes across the double-fork().
 */
void
zed_log_pipe_open(void)
{
	if ((_ctx.pipe_fd[0] != -1) || (_ctx.pipe_fd[1] != -1))
		zed_log_die("Invalid use of zed_log_pipe_open in PID %d",
		    (int)getpid());

	if (pipe(_ctx.pipe_fd) < 0)
		zed_log_die("Failed to create daemonize pipe in PID %d: %s",
		    (int)getpid(), strerror(errno));
}

/*
 * Close the read-half of the daemonize pipe.
 *
 * This should be called by the child after fork()ing from the parent since
 * the child will never read from this pipe.
 */
void
zed_log_pipe_close_reads(void)
{
	if (_ctx.pipe_fd[0] < 0)
		zed_log_die(
		    "Invalid use of zed_log_pipe_close_reads in PID %d",
		    (int)getpid());

	if (close(_ctx.pipe_fd[0]) < 0)
		zed_log_die(
		    "Failed to close reads on daemonize pipe in PID %d: %s",
		    (int)getpid(), strerror(errno));

	_ctx.pipe_fd[0] = -1;
}

/*
 * Close the write-half of the daemonize pipe.
 *
 * This should be called by the parent after fork()ing its child since the
 * parent will never write to this pipe.
 *
 * This should also be called by the child once initialization is complete
 * in order to signal the parent that it can safely exit.
 */
void
zed_log_pipe_close_writes(void)
{
	if (_ctx.pipe_fd[1] < 0)
		zed_log_die(
		    "Invalid use of zed_log_pipe_close_writes in PID %d",
		    (int)getpid());

	if (close(_ctx.pipe_fd[1]) < 0)
		zed_log_die(
		    "Failed to close writes on daemonize pipe in PID %d: %s",
		    (int)getpid(), strerror(errno));

	_ctx.pipe_fd[1] = -1;
}

/*
 * Block on reading from the daemonize pipe until signaled by the child
 * (via zed_log_pipe_close_writes()) that initialization is complete.
 *
 * This should only be called by the parent while waiting to exit after
 * fork()ing the child.
 */
void
zed_log_pipe_wait(void)
{
	ssize_t n;
	char c;

	if (_ctx.pipe_fd[0] < 0)
		zed_log_die("Invalid use of zed_log_pipe_wait in PID %d",
		    (int)getpid());

	for (;;) {
		n = read(_ctx.pipe_fd[0], &c, sizeof (c));
		if (n < 0) {
			if (errno == EINTR)
				continue;
			zed_log_die(
			    "Failed to read from daemonize pipe in PID %d: %s",
			    (int)getpid(), strerror(errno));
		}
		if (n == 0) {
			break;
		}
	}
}

/*
 * Start logging messages at the syslog [priority] level or higher to stderr.
 * Refer to syslog(3) for valid priority values.
 */
void
zed_log_stderr_open(int priority)
{
	_ctx.do_stderr = 1;
	_ctx.priority = priority;
}

/*
 * Stop logging messages to stderr.
 */
void
zed_log_stderr_close(void)
{
	if (_ctx.do_stderr)
		_ctx.do_stderr = 0;
}

/*
 * Start logging messages to syslog.
 * Refer to syslog(3) for valid option/facility values.
 */
void
zed_log_syslog_open(int facility)
{
	_ctx.do_syslog = 1;
	openlog(_ctx.identity, LOG_NDELAY | LOG_PID, facility);
}

/*
 * Stop logging messages to syslog.
 */
void
zed_log_syslog_close(void)
{
	if (_ctx.do_syslog) {
		_ctx.do_syslog = 0;
		closelog();
	}
}

/*
 * Auxiliary function to log a message to syslog and/or stderr.
 */
static void
_zed_log_aux(int priority, const char *fmt, va_list vargs)
{
	char buf[ZED_LOG_MAX_LOG_LEN];
	int n;

	if (!fmt)
		return;

	n = vsnprintf(buf, sizeof (buf), fmt, vargs);
	if ((n < 0) || (n >= sizeof (buf))) {
		buf[sizeof (buf) - 2] = '+';
		buf[sizeof (buf) - 1] = '\0';
	}

	if (_ctx.do_syslog)
		syslog(priority, "%s", buf);

	if (_ctx.do_stderr && (priority <= _ctx.priority))
		fprintf(stderr, "%s\n", buf);
}

/*
 * Log a message at the given [priority] level specified by the printf-style
 * format string [fmt].
 */
void
zed_log_msg(int priority, const char *fmt, ...)
{
	va_list vargs;

	if (fmt) {
		va_start(vargs, fmt);
		_zed_log_aux(priority, fmt, vargs);
		va_end(vargs);
	}
}

/*
 * Log a fatal error message specified by the printf-style format string [fmt].
 */
void
zed_log_die(const char *fmt, ...)
{
	va_list vargs;

	if (fmt) {
		va_start(vargs, fmt);
		_zed_log_aux(LOG_ERR, fmt, vargs);
		va_end(vargs);
	}
	exit(EXIT_FAILURE);
}