syslog_r.c revision 1.6 
1/*	$OpenBSD: syslog_r.c,v 1.6 2014/10/03 15:41:18 bluhm Exp $ */
2/*
3 * Copyright (c) 1983, 1988, 1993
4 *	The Regents of the University of California.  All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the University nor the names of its contributors
15 *    may be used to endorse or promote products derived from this software
16 *    without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31#include <sys/types.h>
32#include <sys/syslog.h>
33#include <sys/uio.h>
34#include <netdb.h>
35
36#include <errno.h>
37#include <fcntl.h>
38#include <paths.h>
39#include <stdio.h>
40#include <string.h>
41#include <time.h>
42#include <unistd.h>
43#include <stdarg.h>
44
45extern char	*__progname;		/* Program name, from crt0. */
46
47int	sendsyslog(const char *, size_t);
48
49void	__vsyslog_r(int pri, struct syslog_data *, size_t (*)(char *, size_t),
50    const char *, va_list);
51
52/* Reentrant version of syslog, i.e. syslog_r() */
53
54/* PRINTFLIKE3 */
55void
56syslog_r(int pri, struct syslog_data *data, const char *fmt, ...)
57{
58	va_list ap;
59
60	va_start(ap, fmt);
61	vsyslog_r(pri, data, fmt, ap);
62	va_end(ap);
63}
64
65void
66vsyslog_r(int pri, struct syslog_data *data, const char *fmt, va_list ap)
67{
68	const char *ident;
69
70	__vsyslog_r(pri, data, NULL, fmt, ap);
71
72	/* close the socket without losing log_tag */
73	ident = data->log_tag;
74	closelog_r(data);
75	data->log_tag = ident;
76}
77
78/*
79 * This is used by both syslog_r and syslog.  The latter supplies
80 * a non-NULL gettime callback for filling in the date, but we also
81 * use the presence of that callback to decide whether it's safe
82 * to call strerror and what the name of the caller is
83 */
84void
85__vsyslog_r(int pri, struct syslog_data *data,
86    size_t (*gettime)(char *, size_t), const char *fmt, va_list ap)
87{
88	int cnt;
89	char ch, *p, *t;
90	int fd, saved_errno, error;
91#define	TBUF_LEN	2048
92#define	FMT_LEN		1024
93	char *conp = NULL, *stdp = NULL, tbuf[TBUF_LEN], fmt_cpy[FMT_LEN];
94	int tbuf_left, fmt_left, prlen;
95
96#define	INTERNALLOG	LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
97	/* Check for invalid bits. */
98	if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) {
99		syslog_r(INTERNALLOG, data,
100		    "syslog%s: unknown facility/priority: %x",
101		    gettime != NULL ? "" : "_r", pri);
102		pri &= LOG_PRIMASK|LOG_FACMASK;
103	}
104
105	/* Check priority against setlogmask values. */
106	if (!(LOG_MASK(LOG_PRI(pri)) & data->log_mask))
107		return;
108
109	saved_errno = errno;
110
111	/* Set default facility if none specified. */
112	if ((pri & LOG_FACMASK) == 0)
113		pri |= data->log_fac;
114
115	p = tbuf;
116	tbuf_left = TBUF_LEN;
117
118#define	DEC()	\
119	do {					\
120		if (prlen < 0)			\
121			prlen = 0;		\
122		if (prlen >= tbuf_left)		\
123			prlen = tbuf_left - 1;	\
124		p += prlen;			\
125		tbuf_left -= prlen;		\
126	} while (0)
127
128	prlen = snprintf(p, tbuf_left, "<%d>", pri);
129	DEC();
130	if (data->log_stat & LOG_CONS)
131		conp = p;
132
133	/*
134	 * syslogd will expand time automagically for reentrant case, and
135	 * for normal case, invoke the callback to do it just do like before
136	 */
137	if (gettime != NULL) {
138		prlen = gettime(p, tbuf_left);
139		DEC();
140	}
141
142	if (data->log_stat & LOG_PERROR)
143		stdp = p;
144	if (data->log_tag == NULL)
145		data->log_tag = __progname;
146	if (data->log_tag != NULL) {
147		prlen = snprintf(p, tbuf_left, "%s", data->log_tag);
148		DEC();
149	}
150	if (data->log_stat & LOG_PID) {
151		prlen = snprintf(p, tbuf_left, "[%ld]", (long)getpid());
152		DEC();
153	}
154	if (data->log_tag != NULL) {
155		if (tbuf_left > 1) {
156			*p++ = ':';
157			tbuf_left--;
158		}
159		if (tbuf_left > 1) {
160			*p++ = ' ';
161			tbuf_left--;
162		}
163	}
164
165	/* strerror() is not reentrant */
166
167	for (t = fmt_cpy, fmt_left = FMT_LEN; (ch = *fmt); ++fmt) {
168		if (ch == '%' && fmt[1] == 'm') {
169			++fmt;
170			if (gettime != NULL) {
171				prlen = snprintf(t, fmt_left, "%s",
172				    strerror(saved_errno));
173			} else {
174				prlen = snprintf(t, fmt_left, "Error %d",
175				    saved_errno);
176			}
177			if (prlen < 0)
178				prlen = 0;
179			if (prlen >= fmt_left)
180				prlen = fmt_left - 1;
181			t += prlen;
182			fmt_left -= prlen;
183		} else if (ch == '%' && fmt[1] == '%' && fmt_left > 2) {
184			*t++ = '%';
185			*t++ = '%';
186			fmt++;
187			fmt_left -= 2;
188		} else {
189			if (fmt_left > 1) {
190				*t++ = ch;
191				fmt_left--;
192			}
193		}
194	}
195	*t = '\0';
196
197	prlen = vsnprintf(p, tbuf_left, fmt_cpy, ap);
198	DEC();
199	cnt = p - tbuf;
200	while (cnt > 0 && p[-1] == '\n') {
201		*(--p) = '\0';
202		--cnt;
203	}
204
205	/* Output to stderr if requested. */
206	if (data->log_stat & LOG_PERROR) {
207		struct iovec iov[2];
208
209		iov[0].iov_base = stdp;
210		iov[0].iov_len = cnt > stdp - tbuf ? cnt - (stdp - tbuf) : 0;
211		iov[1].iov_base = "\n";
212		iov[1].iov_len = 1;
213		(void)writev(STDERR_FILENO, iov, 2);
214	}
215
216	/*
217	 * If the sendsyslog() fails, it means that syslogd
218	 * is not running.
219	 */
220	error = sendsyslog(tbuf, cnt);
221
222	/*
223	 * Output the message to the console; try not to block
224	 * as a blocking console should not stop other processes.
225	 * Make sure the error reported is the one from the syslogd failure.
226	 */
227	if (error == -1 && (data->log_stat & LOG_CONS) &&
228	    (fd = open(_PATH_CONSOLE, O_WRONLY|O_NONBLOCK, 0)) >= 0) {
229		struct iovec iov[2];
230
231		iov[0].iov_base = conp;
232		iov[0].iov_len = cnt > conp - tbuf ? cnt - (conp - tbuf) : 0;
233		iov[1].iov_base = "\r\n";
234		iov[1].iov_len = 2;
235		(void)writev(fd, iov, 2);
236		(void)close(fd);
237	}
238}
239
240void
241openlog_r(const char *ident, int logstat, int logfac, struct syslog_data *data)
242{
243	if (ident != NULL)
244		data->log_tag = ident;
245	data->log_stat = logstat;
246	if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0)
247		data->log_fac = logfac;
248}
249
250void
251closelog_r(struct syslog_data *data)
252{
253	data->log_tag = NULL;
254}
255
256