syslog.c revision 71579 
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  "$FreeBSD: head/lib/libc/gen/syslog.c 71579 2001-01-24 13:01:12Z deischen $";
40#endif /* LIBC_SCCS and not lint */
41
42#include "namespace.h"
43#include <sys/types.h>
44#include <sys/socket.h>
45#include <sys/syslog.h>
46#include <sys/uio.h>
47#include <sys/un.h>
48#include <netdb.h>
49
50#include <errno.h>
51#include <fcntl.h>
52#include <paths.h>
53#include <stdio.h>
54#include <string.h>
55#include <time.h>
56#include <unistd.h>
57
58#if __STDC__
59#include <stdarg.h>
60#else
61#include <varargs.h>
62#endif
63#include "un-namespace.h"
64
65static int	LogFile = -1;		/* fd for log */
66static int	connected;		/* have done connect */
67static int	opened;			/* have done openlog() */
68static int	LogStat = 0;		/* status bits, set by openlog() */
69static const char *LogTag = NULL;	/* string to tag the entry with */
70static int	LogFacility = LOG_USER;	/* default facility code */
71static int	LogMask = 0xff;		/* mask of priorities to be logged */
72extern char	*__progname;		/* Program name, from crt0. */
73
74static void	disconnectlog __P((void)); /* disconnect from syslogd */
75static void	connectlog __P((void));	/* (re)connect to syslogd */
76
77/*
78 * Format of the magic cookie passed through the stdio hook
79 */
80struct bufcookie {
81	char	*base;	/* start of buffer */
82	int	left;
83};
84
85/*
86 * stdio write hook for writing to a static string buffer
87 * XXX: Maybe one day, dynamically allocate it so that the line length
88 *      is `unlimited'.
89 */
90static
91int writehook(cookie, buf, len)
92	void	*cookie;	/* really [struct bufcookie *] */
93	char	*buf;		/* characters to copy */
94	int	len;		/* length to copy */
95{
96	struct bufcookie *h;	/* private `handle' */
97
98	h = (struct bufcookie *)cookie;
99	if (len > h->left) {
100		/* clip in case of wraparound */
101		len = h->left;
102	}
103	if (len > 0) {
104		(void)memcpy(h->base, buf, len); /* `write' it. */
105		h->base += len;
106		h->left -= len;
107	}
108	return 0;
109}
110
111/*
112 * syslog, vsyslog --
113 *	print message on log file; output is intended for syslogd(8).
114 */
115void
116#if __STDC__
117syslog(int pri, const char *fmt, ...)
118#else
119syslog(pri, fmt, va_alist)
120	int pri;
121	char *fmt;
122	va_dcl
123#endif
124{
125	va_list ap;
126
127#if __STDC__
128	va_start(ap, fmt);
129#else
130	va_start(ap);
131#endif
132	vsyslog(pri, fmt, ap);
133	va_end(ap);
134}
135
136void
137vsyslog(pri, fmt, ap)
138	int pri;
139	register const char *fmt;
140	va_list ap;
141{
142	register int cnt;
143	register char ch, *p;
144	time_t now;
145	int fd, saved_errno;
146	char *stdp, tbuf[2048], fmt_cpy[1024];
147	FILE *fp, *fmt_fp;
148	struct bufcookie tbuf_cookie;
149	struct bufcookie fmt_cookie;
150
151#define	INTERNALLOG	LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
152	/* Check for invalid bits. */
153	if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) {
154		syslog(INTERNALLOG,
155		    "syslog: unknown facility/priority: %x", pri);
156		pri &= LOG_PRIMASK|LOG_FACMASK;
157	}
158
159	/* Check priority against setlogmask values. */
160	if (!(LOG_MASK(LOG_PRI(pri)) & LogMask))
161		return;
162
163	saved_errno = errno;
164
165	/* Set default facility if none specified. */
166	if ((pri & LOG_FACMASK) == 0)
167		pri |= LogFacility;
168
169	/* Create the primary stdio hook */
170	tbuf_cookie.base = tbuf;
171	tbuf_cookie.left = sizeof(tbuf);
172	fp = fwopen(&tbuf_cookie, writehook);
173	if (fp == NULL)
174		return;
175
176	/* Build the message. */
177	(void)time(&now);
178	(void)fprintf(fp, "<%d>", pri);
179	(void)fprintf(fp, "%.15s ", ctime(&now) + 4);
180	if (LogStat & LOG_PERROR) {
181		/* Transfer to string buffer */
182		(void)fflush(fp);
183		stdp = tbuf + (sizeof(tbuf) - tbuf_cookie.left);
184	}
185	if (LogTag == NULL)
186		LogTag = __progname;
187	if (LogTag != NULL)
188		(void)fprintf(fp, "%s", LogTag);
189	if (LogStat & LOG_PID)
190		(void)fprintf(fp, "[%d]", getpid());
191	if (LogTag != NULL) {
192		(void)fprintf(fp, ": ");
193	}
194
195	/* Check to see if we can skip expanding the %m */
196	if (strstr(fmt, "%m")) {
197
198		/* Create the second stdio hook */
199		fmt_cookie.base = fmt_cpy;
200		fmt_cookie.left = sizeof(fmt_cpy) - 1;
201		fmt_fp = fwopen(&fmt_cookie, writehook);
202		if (fmt_fp == NULL) {
203			fclose(fp);
204			return;
205		}
206
207		/* Substitute error message for %m. */
208		for ( ; (ch = *fmt); ++fmt)
209			if (ch == '%' && fmt[1] == 'm') {
210				++fmt;
211				fputs(strerror(saved_errno), fmt_fp);
212			} else
213				fputc(ch, fmt_fp);
214
215		/* Null terminate if room */
216		fputc(0, fmt_fp);
217		fclose(fmt_fp);
218
219		/* Guarantee null termination */
220		fmt_cpy[sizeof(fmt_cpy) - 1] = '\0';
221
222		fmt = fmt_cpy;
223	}
224
225	(void)vfprintf(fp, fmt, ap);
226	(void)fclose(fp);
227
228	cnt = sizeof(tbuf) - tbuf_cookie.left;
229
230	/* Output to stderr if requested. */
231	if (LogStat & LOG_PERROR) {
232		struct iovec iov[2];
233		register struct iovec *v = iov;
234
235		v->iov_base = stdp;
236		v->iov_len = cnt - (stdp - tbuf);
237		++v;
238		v->iov_base = "\n";
239		v->iov_len = 1;
240		(void)_writev(STDERR_FILENO, iov, 2);
241	}
242
243	/* Get connected, output the message to the local logger. */
244	if (!opened)
245		openlog(LogTag, LogStat | LOG_NDELAY, 0);
246	connectlog();
247	if (send(LogFile, tbuf, cnt, 0) >= 0)
248		return;
249
250	/*
251	 * If the send() failed, the odds are syslogd was restarted.
252	 * Make one (only) attempt to reconnect to /dev/log.
253	 */
254	disconnectlog();
255	connectlog();
256	if (send(LogFile, tbuf, cnt, 0) >= 0)
257		return;
258
259	/*
260	 * Output the message to the console; don't worry about blocking,
261	 * if console blocks everything will.  Make sure the error reported
262	 * is the one from the syslogd failure.
263	 */
264	if (LogStat & LOG_CONS &&
265	    (fd = _open(_PATH_CONSOLE, O_WRONLY, 0)) >= 0) {
266		struct iovec iov[2];
267		register struct iovec *v = iov;
268
269		p = strchr(tbuf, '>') + 1;
270		v->iov_base = p;
271		v->iov_len = cnt - (p - tbuf);
272		++v;
273		v->iov_base = "\r\n";
274		v->iov_len = 2;
275		(void)_writev(fd, iov, 2);
276		(void)_close(fd);
277	}
278}
279static void
280disconnectlog()
281{
282	/*
283	 * If the user closed the FD and opened another in the same slot,
284	 * that's their problem.  They should close it before calling on
285	 * system services.
286	 */
287	if (LogFile != -1) {
288		_close(LogFile);
289		LogFile = -1;
290	}
291	connected = 0;			/* retry connect */
292}
293
294static void
295connectlog()
296{
297	struct sockaddr_un SyslogAddr;	/* AF_UNIX address of local logger */
298
299	if (LogFile == -1) {
300		if ((LogFile = _socket(AF_UNIX, SOCK_DGRAM, 0)) == -1)
301			return;
302		(void)_fcntl(LogFile, F_SETFD, 1);
303	}
304	if (LogFile != -1 && !connected) {
305		SyslogAddr.sun_len = sizeof(SyslogAddr);
306		SyslogAddr.sun_family = AF_UNIX;
307		(void)strncpy(SyslogAddr.sun_path, _PATH_LOG,
308		    sizeof SyslogAddr.sun_path);
309		connected = _connect(LogFile, (struct sockaddr *)&SyslogAddr,
310			sizeof(SyslogAddr)) != -1;
311
312		if (!connected) {
313			/*
314			 * Try the old "/dev/log" path, for backward
315			 * compatibility.
316			 */
317			(void)strncpy(SyslogAddr.sun_path, _PATH_OLDLOG,
318			    sizeof SyslogAddr.sun_path);
319			connected = _connect(LogFile,
320				(struct sockaddr *)&SyslogAddr,
321				sizeof(SyslogAddr)) != -1;
322		}
323
324		if (!connected) {
325			(void)_close(LogFile);
326			LogFile = -1;
327		}
328	}
329}
330
331void
332openlog(ident, logstat, logfac)
333	const char *ident;
334	int logstat, logfac;
335{
336	if (ident != NULL)
337		LogTag = ident;
338	LogStat = logstat;
339	if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0)
340		LogFacility = logfac;
341
342	if (LogStat & LOG_NDELAY)	/* open immediately */
343		connectlog();
344
345	opened = 1;	/* ident and facility has been set */
346}
347
348void
349closelog()
350{
351	(void)_close(LogFile);
352	LogFile = -1;
353	connected = 0;
354}
355
356/* setlogmask -- set the log mask level */
357int
358setlogmask(pmask)
359	int pmask;
360{
361	int omask;
362
363	omask = LogMask;
364	if (pmask != 0)
365		LogMask = pmask;
366	return (omask);
367}
368