syslog.c revision 24068 
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)
35/*
36static char sccsid[] = "@(#)syslog.c	8.5 (Berkeley) 4/29/95";
37*/
38static const char rcsid[] =
39  "$Id: syslog.c,v 1.12 1997/03/11 11:52:33 peter Exp $";
40#endif /* LIBC_SCCS and not lint */
41
42#include <sys/types.h>
43#include <sys/socket.h>
44#include <sys/syslog.h>
45#include <sys/uio.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
62static int	LogFile = -1;		/* fd for log */
63static int	connected;		/* have done connect */
64static int	opened;			/* have done openlog() */
65static int	LogStat = 0;		/* status bits, set by openlog() */
66static const char *LogTag = NULL;	/* string to tag the entry with */
67static int	LogFacility = LOG_USER;	/* default facility code */
68static int	LogMask = 0xff;		/* mask of priorities to be logged */
69extern char	*__progname;		/* Program name, from crt0. */
70
71static void	disconnectlog __P((void)); /* disconnect from syslogd */
72static void	connectlog __P((void));	/* (re)connect to syslogd */
73
74/*
75 * Format of the magic cookie passed through the stdio hook
76 */
77struct bufcookie {
78	char	*base;	/* start of buffer */
79	int	left;
80};
81
82/*
83 * stdio write hook for writing to a static string buffer
84 * XXX: Maybe one day, dynamically allocate it so that the line length
85 *      is `unlimited'.
86 */
87static
88int writehook(cookie, buf, len)
89	void	*cookie;	/* really [struct bufcookie *] */
90	char	*buf;		/* characters to copy */
91	int	len;		/* length to copy */
92{
93	struct bufcookie *h;	/* private `handle' */
94
95	h = (struct bufcookie *)cookie;
96	if (len > h->left) {
97		/* clip in case of wraparound */
98		len = h->left;
99	}
100	if (len > 0) {
101		(void)memcpy(h->base, buf, len); /* `write' it. */
102		h->base += len;
103		h->left -= len;
104	}
105	return 0;
106}
107
108/*
109 * syslog, vsyslog --
110 *	print message on log file; output is intended for syslogd(8).
111 */
112void
113#if __STDC__
114syslog(int pri, const char *fmt, ...)
115#else
116syslog(pri, fmt, va_alist)
117	int pri;
118	char *fmt;
119	va_dcl
120#endif
121{
122	va_list ap;
123
124#if __STDC__
125	va_start(ap, fmt);
126#else
127	va_start(ap);
128#endif
129	vsyslog(pri, fmt, ap);
130	va_end(ap);
131}
132
133void
134vsyslog(pri, fmt, ap)
135	int pri;
136	register const char *fmt;
137	va_list ap;
138{
139	register int cnt;
140	register char ch, *p;
141	time_t now;
142	int fd, saved_errno;
143	char *stdp, tbuf[2048], fmt_cpy[1024];
144	FILE *fp, *fmt_fp;
145	struct bufcookie tbuf_cookie;
146	struct bufcookie fmt_cookie;
147
148#define	INTERNALLOG	LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
149	/* Check for invalid bits. */
150	if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) {
151		syslog(INTERNALLOG,
152		    "syslog: unknown facility/priority: %x", pri);
153		pri &= LOG_PRIMASK|LOG_FACMASK;
154	}
155
156	/* Check priority against setlogmask values. */
157	if (!(LOG_MASK(LOG_PRI(pri)) & LogMask))
158		return;
159
160	saved_errno = errno;
161
162	/* Set default facility if none specified. */
163	if ((pri & LOG_FACMASK) == 0)
164		pri |= LogFacility;
165
166	/* Create the primary stdio hook */
167	tbuf_cookie.base = tbuf;
168	tbuf_cookie.left = sizeof(tbuf);
169	fp = fwopen(&tbuf_cookie, writehook);
170	if (fp == NULL)
171		return;
172
173	/* Build the message. */
174	(void)time(&now);
175	(void)fprintf(fp, "<%d>", pri);
176	(void)fprintf(fp, "%.15s ", ctime(&now) + 4);
177	if (LogStat & LOG_PERROR) {
178		/* Transfer to string buffer */
179		(void)fflush(fp);
180		stdp = tbuf + (sizeof(tbuf) - tbuf_cookie.left);
181	}
182	if (LogTag == NULL)
183		LogTag = __progname;
184	if (LogTag != NULL)
185		(void)fprintf(fp, "%s", LogTag);
186	if (LogStat & LOG_PID)
187		(void)fprintf(fp, "[%d]", getpid());
188	if (LogTag != NULL) {
189		(void)fprintf(fp, ": ");
190	}
191
192	/* Check to see if we can skip expanding the %m */
193	if (strstr(fmt, "%m")) {
194
195		/* Create the second stdio hook */
196		fmt_cookie.base = fmt_cpy;
197		fmt_cookie.left = sizeof(fmt_cpy) - 1;
198		fmt_fp = fwopen(&fmt_cookie, writehook);
199		if (fmt_fp == NULL) {
200			fclose(fp);
201			return;
202		}
203
204		/* Substitute error message for %m. */
205		for ( ; (ch = *fmt); ++fmt)
206			if (ch == '%' && fmt[1] == 'm') {
207				++fmt;
208				fputs(strerror(saved_errno), fmt_fp);
209			} else
210				fputc(ch, fmt_fp);
211
212		/* Null terminate if room */
213		fputc(0, fmt_fp);
214		fclose(fmt_fp);
215
216		/* Guarantee null termination */
217		fmt_cpy[sizeof(fmt_cpy) - 1] = '\0';
218
219		fmt = fmt_cpy;
220	}
221
222	(void)vfprintf(fp, fmt, ap);
223	(void)fclose(fp);
224
225	cnt = sizeof(tbuf) - tbuf_cookie.left;
226
227	/* Output to stderr if requested. */
228	if (LogStat & LOG_PERROR) {
229		struct iovec iov[2];
230		register struct iovec *v = iov;
231
232		v->iov_base = stdp;
233		v->iov_len = cnt - (stdp - tbuf);
234		++v;
235		v->iov_base = "\n";
236		v->iov_len = 1;
237		(void)writev(STDERR_FILENO, iov, 2);
238	}
239
240	/* Get connected, output the message to the local logger. */
241	if (!opened)
242		openlog(LogTag, LogStat | LOG_NDELAY, 0);
243	connectlog();
244	if (send(LogFile, tbuf, cnt, 0) >= 0)
245		return;
246
247	/*
248	 * If the send() failed, the odds are syslogd was restarted.
249	 * Make one (only) attempt to reconnect to /dev/log.
250	 */
251	disconnectlog();
252	connectlog();
253	if (send(LogFile, tbuf, cnt, 0) >= 0)
254		return;
255
256	/*
257	 * Output the message to the console; don't worry about blocking,
258	 * if console blocks everything will.  Make sure the error reported
259	 * is the one from the syslogd failure.
260	 */
261	if (LogStat & LOG_CONS &&
262	    (fd = open(_PATH_CONSOLE, O_WRONLY, 0)) >= 0) {
263		struct iovec iov[2];
264		register struct iovec *v = iov;
265
266		p = strchr(tbuf, '>') + 1;
267		v->iov_base = p;
268		v->iov_len = cnt - (p - tbuf);
269		++v;
270		v->iov_base = "\r\n";
271		v->iov_len = 2;
272		(void)writev(fd, iov, 2);
273		(void)close(fd);
274	}
275}
276static void
277disconnectlog()
278{
279	/*
280	 * If the user closed the FD and opened another in the same slot,
281	 * that's their problem.  They should close it before calling on
282	 * system services.
283	 */
284	if (LogFile != -1) {
285		close(LogFile);
286		LogFile = -1;
287	}
288	connected = 0;			/* retry connect */
289}
290
291static void
292connectlog()
293{
294	struct sockaddr SyslogAddr;	/* AF_UNIX address of local logger */
295
296	if (LogFile == -1) {
297		if ((LogFile = socket(AF_UNIX, SOCK_DGRAM, 0)) == -1)
298			return;
299		(void)fcntl(LogFile, F_SETFD, 1);
300	}
301	if (LogFile != -1 && !connected) {
302		SyslogAddr.sa_len = sizeof(SyslogAddr);
303		SyslogAddr.sa_family = AF_UNIX;
304		(void)strncpy(SyslogAddr.sa_data, _PATH_LOG,
305		    sizeof(SyslogAddr.sa_data));
306		connected = connect(LogFile, &SyslogAddr,
307			sizeof(SyslogAddr)) != -1;
308
309		if (!connected) {
310			/*
311			 * Try the old "/dev/log" path, for backward
312			 * compatibility.
313			 */
314			(void)strncpy(SyslogAddr.sa_data, _PATH_OLDLOG,
315			    sizeof(SyslogAddr.sa_data));
316			connected = connect(LogFile, &SyslogAddr,
317				sizeof(SyslogAddr)) != -1;
318		}
319
320		if (!connected) {
321			(void)close(LogFile);
322			LogFile = -1;
323		}
324	}
325}
326
327void
328openlog(ident, logstat, logfac)
329	const char *ident;
330	int logstat, logfac;
331{
332	if (ident != NULL)
333		LogTag = ident;
334	LogStat = logstat;
335	if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0)
336		LogFacility = logfac;
337
338	if (LogStat & LOG_NDELAY)	/* open immediately */
339		connectlog();
340
341	opened = 1;	/* ident and facility has been set */
342}
343
344void
345closelog()
346{
347	(void)close(LogFile);
348	LogFile = -1;
349	connected = 0;
350}
351
352/* setlogmask -- set the log mask level */
353int
354setlogmask(pmask)
355	int pmask;
356{
357	int omask;
358
359	omask = LogMask;
360	if (pmask != 0)
361		LogMask = pmask;
362	return (omask);
363}
364