syslog.c revision 91940 
1/*
2 * Copyright (c) 1983, 1988, 1993
3 *	The Regents of the University of California.  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 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#if defined(LIBC_SCCS) && !defined(lint)
35static char sccsid[] = "@(#)syslog.c	8.5 (Berkeley) 4/29/95";
36#endif /* LIBC_SCCS and not lint */
37#include <sys/cdefs.h>
38__FBSDID("$FreeBSD: head/lib/libc/gen/syslog.c 91940 2002-03-09 11:38:01Z dwmalone $");
39
40#include "namespace.h"
41#include <sys/types.h>
42#include <sys/socket.h>
43#include <sys/syslog.h>
44#include <sys/uio.h>
45#include <sys/un.h>
46#include <netdb.h>
47
48#include <errno.h>
49#include <fcntl.h>
50#include <paths.h>
51#include <stdio.h>
52#include <string.h>
53#include <time.h>
54#include <unistd.h>
55
56#if __STDC__
57#include <stdarg.h>
58#else
59#include <varargs.h>
60#endif
61#include "un-namespace.h"
62
63static int	LogFile = -1;		/* fd for log */
64static int	connected;		/* have done connect */
65static int	opened;			/* have done openlog() */
66static int	LogStat = 0;		/* status bits, set by openlog() */
67static const char *LogTag = NULL;	/* string to tag the entry with */
68static int	LogFacility = LOG_USER;	/* default facility code */
69static int	LogMask = 0xff;		/* mask of priorities to be logged */
70extern char	*__progname;		/* Program name, from crt0. */
71
72static void	disconnectlog(void); /* disconnect from syslogd */
73static void	connectlog(void);	/* (re)connect to syslogd */
74
75/*
76 * Format of the magic cookie passed through the stdio hook
77 */
78struct bufcookie {
79	char	*base;	/* start of buffer */
80	int	left;
81};
82
83/*
84 * stdio write hook for writing to a static string buffer
85 * XXX: Maybe one day, dynamically allocate it so that the line length
86 *      is `unlimited'.
87 */
88static
89int writehook(cookie, buf, len)
90	void	*cookie;	/* really [struct bufcookie *] */
91	char	*buf;		/* characters to copy */
92	int	len;		/* length to copy */
93{
94	struct bufcookie *h;	/* private `handle' */
95
96	h = (struct bufcookie *)cookie;
97	if (len > h->left) {
98		/* clip in case of wraparound */
99		len = h->left;
100	}
101	if (len > 0) {
102		(void)memcpy(h->base, buf, len); /* `write' it. */
103		h->base += len;
104		h->left -= len;
105	}
106	return 0;
107}
108
109/*
110 * syslog, vsyslog --
111 *	print message on log file; output is intended for syslogd(8).
112 */
113void
114#if __STDC__
115syslog(int pri, const char *fmt, ...)
116#else
117syslog(pri, fmt, va_alist)
118	int pri;
119	char *fmt;
120	va_dcl
121#endif
122{
123	va_list ap;
124
125#if __STDC__
126	va_start(ap, fmt);
127#else
128	va_start(ap);
129#endif
130	vsyslog(pri, fmt, ap);
131	va_end(ap);
132}
133
134void
135vsyslog(pri, fmt, ap)
136	int pri;
137	const char *fmt;
138	va_list ap;
139{
140	int cnt;
141	char ch, *p;
142	time_t now;
143	int fd, saved_errno;
144	char *stdp, tbuf[2048], fmt_cpy[1024], timbuf[26];
145	FILE *fp, *fmt_fp;
146	struct bufcookie tbuf_cookie;
147	struct bufcookie fmt_cookie;
148
149#define	INTERNALLOG	LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
150	/* Check for invalid bits. */
151	if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) {
152		syslog(INTERNALLOG,
153		    "syslog: unknown facility/priority: %x", pri);
154		pri &= LOG_PRIMASK|LOG_FACMASK;
155	}
156
157	/* Check priority against setlogmask values. */
158	if (!(LOG_MASK(LOG_PRI(pri)) & LogMask))
159		return;
160
161	saved_errno = errno;
162
163	/* Set default facility if none specified. */
164	if ((pri & LOG_FACMASK) == 0)
165		pri |= LogFacility;
166
167	/* Create the primary stdio hook */
168	tbuf_cookie.base = tbuf;
169	tbuf_cookie.left = sizeof(tbuf);
170	fp = fwopen(&tbuf_cookie, writehook);
171	if (fp == NULL)
172		return;
173
174	/* Build the message. */
175	(void)time(&now);
176	(void)fprintf(fp, "<%d>", pri);
177	(void)fprintf(fp, "%.15s ", ctime_r(&now, timbuf) + 4);
178	if (LogStat & LOG_PERROR) {
179		/* Transfer to string buffer */
180		(void)fflush(fp);
181		stdp = tbuf + (sizeof(tbuf) - tbuf_cookie.left);
182	}
183	if (LogTag == NULL)
184		LogTag = __progname;
185	if (LogTag != NULL)
186		(void)fprintf(fp, "%s", LogTag);
187	if (LogStat & LOG_PID)
188		(void)fprintf(fp, "[%d]", getpid());
189	if (LogTag != NULL) {
190		(void)fprintf(fp, ": ");
191	}
192
193	/* Check to see if we can skip expanding the %m */
194	if (strstr(fmt, "%m")) {
195
196		/* Create the second stdio hook */
197		fmt_cookie.base = fmt_cpy;
198		fmt_cookie.left = sizeof(fmt_cpy) - 1;
199		fmt_fp = fwopen(&fmt_cookie, writehook);
200		if (fmt_fp == NULL) {
201			fclose(fp);
202			return;
203		}
204
205		/* Substitute error message for %m. */
206		for ( ; (ch = *fmt); ++fmt)
207			if (ch == '%' && fmt[1] == 'm') {
208				++fmt;
209				fputs(strerror(saved_errno), fmt_fp);
210			} else
211				fputc(ch, fmt_fp);
212
213		/* Null terminate if room */
214		fputc(0, fmt_fp);
215		fclose(fmt_fp);
216
217		/* Guarantee null termination */
218		fmt_cpy[sizeof(fmt_cpy) - 1] = '\0';
219
220		fmt = fmt_cpy;
221	}
222
223	(void)vfprintf(fp, fmt, ap);
224	(void)fclose(fp);
225
226	cnt = sizeof(tbuf) - tbuf_cookie.left;
227
228	/* Output to stderr if requested. */
229	if (LogStat & LOG_PERROR) {
230		struct iovec iov[2];
231		struct iovec *v = iov;
232
233		v->iov_base = stdp;
234		v->iov_len = cnt - (stdp - tbuf);
235		++v;
236		v->iov_base = "\n";
237		v->iov_len = 1;
238		(void)_writev(STDERR_FILENO, iov, 2);
239	}
240
241	/* Get connected, output the message to the local logger. */
242	if (!opened)
243		openlog(LogTag, LogStat | LOG_NDELAY, 0);
244	connectlog();
245	if (send(LogFile, tbuf, cnt, 0) >= 0)
246		return;
247
248	/*
249	 * If the send() failed, the odds are syslogd was restarted.
250	 * Make one (only) attempt to reconnect to /dev/log.
251	 */
252	disconnectlog();
253	connectlog();
254	if (send(LogFile, tbuf, cnt, 0) >= 0)
255		return;
256
257	/*
258	 * Output the message to the console; try not to block
259	 * as a blocking console should not stop other processes.
260	 * Make sure the error reported is the one from the syslogd failure.
261	 */
262	if (LogStat & LOG_CONS &&
263	    (fd = _open(_PATH_CONSOLE, O_WRONLY|O_NONBLOCK, 0)) >= 0) {
264		struct iovec iov[2];
265		struct iovec *v = iov;
266
267		p = strchr(tbuf, '>') + 1;
268		v->iov_base = p;
269		v->iov_len = cnt - (p - tbuf);
270		++v;
271		v->iov_base = "\r\n";
272		v->iov_len = 2;
273		(void)_writev(fd, iov, 2);
274		(void)_close(fd);
275	}
276}
277static void
278disconnectlog()
279{
280	/*
281	 * If the user closed the FD and opened another in the same slot,
282	 * that's their problem.  They should close it before calling on
283	 * system services.
284	 */
285	if (LogFile != -1) {
286		_close(LogFile);
287		LogFile = -1;
288	}
289	connected = 0;			/* retry connect */
290}
291
292static void
293connectlog()
294{
295	struct sockaddr_un SyslogAddr;	/* AF_UNIX address of local logger */
296
297	if (LogFile == -1) {
298		if ((LogFile = _socket(AF_UNIX, SOCK_DGRAM, 0)) == -1)
299			return;
300		(void)_fcntl(LogFile, F_SETFD, 1);
301	}
302	if (LogFile != -1 && !connected) {
303		SyslogAddr.sun_len = sizeof(SyslogAddr);
304		SyslogAddr.sun_family = AF_UNIX;
305		(void)strncpy(SyslogAddr.sun_path, _PATH_LOG,
306		    sizeof SyslogAddr.sun_path);
307		connected = _connect(LogFile, (struct sockaddr *)&SyslogAddr,
308			sizeof(SyslogAddr)) != -1;
309
310		if (!connected) {
311			/*
312			 * Try the old "/dev/log" path, for backward
313			 * compatibility.
314			 */
315			(void)strncpy(SyslogAddr.sun_path, _PATH_OLDLOG,
316			    sizeof SyslogAddr.sun_path);
317			connected = _connect(LogFile,
318				(struct sockaddr *)&SyslogAddr,
319				sizeof(SyslogAddr)) != -1;
320		}
321
322		if (!connected) {
323			(void)_close(LogFile);
324			LogFile = -1;
325		}
326	}
327}
328
329void
330openlog(ident, logstat, logfac)
331	const char *ident;
332	int logstat, logfac;
333{
334	if (ident != NULL)
335		LogTag = ident;
336	LogStat = logstat;
337	if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0)
338		LogFacility = logfac;
339
340	if (LogStat & LOG_NDELAY)	/* open immediately */
341		connectlog();
342
343	opened = 1;	/* ident and facility has been set */
344}
345
346void
347closelog()
348{
349	(void)_close(LogFile);
350	LogFile = -1;
351	connected = 0;
352}
353
354/* setlogmask -- set the log mask level */
355int
356setlogmask(pmask)
357	int pmask;
358{
359	int omask;
360
361	omask = LogMask;
362	if (pmask != 0)
363		LogMask = pmask;
364	return (omask);
365}
366