syslog.c revision 129091 
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 129091 2004-05-10 17:12:52Z dds $");
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 <stdlib.h>
53#include <string.h>
54#include <time.h>
55#include <unistd.h>
56
57#include <stdarg.h>
58#include "un-namespace.h"
59
60#include "libc_private.h"
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 */
69
70static void	disconnectlog(void); /* disconnect from syslogd */
71static void	connectlog(void);	/* (re)connect to syslogd */
72
73/*
74 * Format of the magic cookie passed through the stdio hook
75 */
76struct bufcookie {
77	char	*base;	/* start of buffer */
78	int	left;
79};
80
81/*
82 * stdio write hook for writing to a static string buffer
83 * XXX: Maybe one day, dynamically allocate it so that the line length
84 *      is `unlimited'.
85 */
86static
87int writehook(cookie, buf, len)
88	void	*cookie;	/* really [struct bufcookie *] */
89	char	*buf;		/* characters to copy */
90	int	len;		/* length to copy */
91{
92	struct bufcookie *h;	/* private `handle' */
93
94	h = (struct bufcookie *)cookie;
95	if (len > h->left) {
96		/* clip in case of wraparound */
97		len = h->left;
98	}
99	if (len > 0) {
100		(void)memcpy(h->base, buf, len); /* `write' it. */
101		h->base += len;
102		h->left -= len;
103	}
104	return 0;
105}
106
107/*
108 * syslog, vsyslog --
109 *	print message on log file; output is intended for syslogd(8).
110 */
111void
112syslog(int pri, const char *fmt, ...)
113{
114	va_list ap;
115
116	va_start(ap, fmt);
117	vsyslog(pri, fmt, ap);
118	va_end(ap);
119}
120
121void
122vsyslog(pri, fmt, ap)
123	int pri;
124	const char *fmt;
125	va_list ap;
126{
127	int cnt;
128	char ch, *p;
129	time_t now;
130	int fd, saved_errno;
131	char *stdp, tbuf[2048], fmt_cpy[1024], timbuf[26];
132	FILE *fp, *fmt_fp;
133	struct bufcookie tbuf_cookie;
134	struct bufcookie fmt_cookie;
135
136#define	INTERNALLOG	LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
137	/* Check for invalid bits. */
138	if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) {
139		syslog(INTERNALLOG,
140		    "syslog: unknown facility/priority: %x", pri);
141		pri &= LOG_PRIMASK|LOG_FACMASK;
142	}
143
144	/* Check priority against setlogmask values. */
145	if (!(LOG_MASK(LOG_PRI(pri)) & LogMask))
146		return;
147
148	saved_errno = errno;
149
150	/* Set default facility if none specified. */
151	if ((pri & LOG_FACMASK) == 0)
152		pri |= LogFacility;
153
154	/* Create the primary stdio hook */
155	tbuf_cookie.base = tbuf;
156	tbuf_cookie.left = sizeof(tbuf);
157	fp = fwopen(&tbuf_cookie, writehook);
158	if (fp == NULL)
159		return;
160
161	/* Build the message. */
162	(void)time(&now);
163	(void)fprintf(fp, "<%d>", pri);
164	(void)fprintf(fp, "%.15s ", ctime_r(&now, timbuf) + 4);
165	if (LogStat & LOG_PERROR) {
166		/* Transfer to string buffer */
167		(void)fflush(fp);
168		stdp = tbuf + (sizeof(tbuf) - tbuf_cookie.left);
169	}
170	if (LogTag == NULL)
171		LogTag = _getprogname();
172	if (LogTag != NULL)
173		(void)fprintf(fp, "%s", LogTag);
174	if (LogStat & LOG_PID)
175		(void)fprintf(fp, "[%d]", getpid());
176	if (LogTag != NULL) {
177		(void)fprintf(fp, ": ");
178	}
179
180	/* Check to see if we can skip expanding the %m */
181	if (strstr(fmt, "%m")) {
182
183		/* Create the second stdio hook */
184		fmt_cookie.base = fmt_cpy;
185		fmt_cookie.left = sizeof(fmt_cpy) - 1;
186		fmt_fp = fwopen(&fmt_cookie, writehook);
187		if (fmt_fp == NULL) {
188			fclose(fp);
189			return;
190		}
191
192		/*
193		 * Substitute error message for %m.  Be careful not to
194		 * molest an escaped percent "%%m".  We want to pass it
195		 * on untouched as the format is later parsed by vfprintf.
196		 */
197		for ( ; (ch = *fmt); ++fmt) {
198			if (ch == '%' && fmt[1] == 'm') {
199				++fmt;
200				fputs(strerror(saved_errno), fmt_fp);
201			} else if (ch == '%' && fmt[1] == '%') {
202				++fmt;
203				fputc(ch, fmt_fp);
204				fputc(ch, fmt_fp);
205			} else {
206				fputc(ch, fmt_fp);
207			}
208		}
209
210		/* Null terminate if room */
211		fputc(0, fmt_fp);
212		fclose(fmt_fp);
213
214		/* Guarantee null termination */
215		fmt_cpy[sizeof(fmt_cpy) - 1] = '\0';
216
217		fmt = fmt_cpy;
218	}
219
220	(void)vfprintf(fp, fmt, ap);
221	(void)fclose(fp);
222
223	cnt = sizeof(tbuf) - tbuf_cookie.left;
224
225	/* Remove a trailing newline */
226	if (tbuf[cnt - 1] == '\n')
227		cnt--;
228
229	/* Output to stderr if requested. */
230	if (LogStat & LOG_PERROR) {
231		struct iovec iov[2];
232		struct iovec *v = iov;
233
234		v->iov_base = stdp;
235		v->iov_len = cnt - (stdp - tbuf);
236		++v;
237		v->iov_base = "\n";
238		v->iov_len = 1;
239		(void)_writev(STDERR_FILENO, iov, 2);
240	}
241
242	/* Get connected, output the message to the local logger. */
243	if (!opened)
244		openlog(LogTag, LogStat | LOG_NDELAY, 0);
245	connectlog();
246	if (send(LogFile, tbuf, cnt, 0) >= 0)
247		return;
248
249	/*
250	 * If the send() failed, the odds are syslogd was restarted.
251	 * Make one (only) attempt to reconnect to /dev/log.
252	 */
253	disconnectlog();
254	connectlog();
255	if (send(LogFile, tbuf, cnt, 0) >= 0)
256		return;
257
258	/*
259	 * Output the message to the console; try not to block
260	 * as a blocking console should not stop other processes.
261	 * Make sure the error reported is the one from the syslogd failure.
262	 */
263	if (LogStat & LOG_CONS &&
264	    (fd = _open(_PATH_CONSOLE, O_WRONLY|O_NONBLOCK, 0)) >= 0) {
265		struct iovec iov[2];
266		struct iovec *v = iov;
267
268		p = strchr(tbuf, '>') + 1;
269		v->iov_base = p;
270		v->iov_len = cnt - (p - tbuf);
271		++v;
272		v->iov_base = "\r\n";
273		v->iov_len = 2;
274		(void)_writev(fd, iov, 2);
275		(void)_close(fd);
276	}
277}
278static void
279disconnectlog()
280{
281	/*
282	 * If the user closed the FD and opened another in the same slot,
283	 * that's their problem.  They should close it before calling on
284	 * system services.
285	 */
286	if (LogFile != -1) {
287		_close(LogFile);
288		LogFile = -1;
289	}
290	connected = 0;			/* retry connect */
291}
292
293static void
294connectlog()
295{
296	struct sockaddr_un SyslogAddr;	/* AF_UNIX address of local logger */
297
298	if (LogFile == -1) {
299		if ((LogFile = _socket(AF_UNIX, SOCK_DGRAM, 0)) == -1)
300			return;
301		(void)_fcntl(LogFile, F_SETFD, 1);
302	}
303	if (LogFile != -1 && !connected) {
304		SyslogAddr.sun_len = sizeof(SyslogAddr);
305		SyslogAddr.sun_family = AF_UNIX;
306		(void)strncpy(SyslogAddr.sun_path, _PATH_LOG,
307		    sizeof SyslogAddr.sun_path);
308		connected = _connect(LogFile, (struct sockaddr *)&SyslogAddr,
309			sizeof(SyslogAddr)) != -1;
310
311		if (!connected) {
312			/*
313			 * Try the old "/dev/log" path, for backward
314			 * compatibility.
315			 */
316			(void)strncpy(SyslogAddr.sun_path, _PATH_OLDLOG,
317			    sizeof SyslogAddr.sun_path);
318			connected = _connect(LogFile,
319				(struct sockaddr *)&SyslogAddr,
320				sizeof(SyslogAddr)) != -1;
321		}
322
323		if (!connected) {
324			(void)_close(LogFile);
325			LogFile = -1;
326		}
327	}
328}
329
330void
331openlog(ident, logstat, logfac)
332	const char *ident;
333	int logstat, logfac;
334{
335	if (ident != NULL)
336		LogTag = ident;
337	LogStat = logstat;
338	if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0)
339		LogFacility = logfac;
340
341	if (LogStat & LOG_NDELAY)	/* open immediately */
342		connectlog();
343
344	opened = 1;	/* ident and facility has been set */
345}
346
347void
348closelog()
349{
350	(void)_close(LogFile);
351	LogFile = -1;
352	LogTag = NULL;
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