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syslog.c revision 1.28 
      1 /*	$NetBSD: syslog.c,v 1.28 2002/05/26 14:03:20 wiz Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1983, 1988, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #include <sys/cdefs.h>
     37 #if defined(LIBC_SCCS) && !defined(lint)
     38 #if 0
     39 static char sccsid[] = "@(#)syslog.c	8.5 (Berkeley) 4/29/95";
     40 #else
     41 __RCSID("$NetBSD: syslog.c,v 1.28 2002/05/26 14:03:20 wiz Exp $");
     42 #endif
     43 #endif /* LIBC_SCCS and not lint */
     44 
     45 #include "namespace.h"
     46 #include <sys/types.h>
     47 #include <sys/socket.h>
     48 #include <sys/syslog.h>
     49 #include <sys/uio.h>
     50 #include <sys/un.h>
     51 #include <netdb.h>
     52 
     53 #include <errno.h>
     54 #include <fcntl.h>
     55 #include <paths.h>
     56 #include <stdarg.h>
     57 #include <stdio.h>
     58 #include <stdlib.h>
     59 #include <string.h>
     60 #include <time.h>
     61 #include <unistd.h>
     62 #include "reentrant.h"
     63 
     64 #ifdef __weak_alias
     65 __weak_alias(closelog,_closelog)
     66 __weak_alias(openlog,_openlog)
     67 __weak_alias(setlogmask,_setlogmask)
     68 __weak_alias(syslog,_syslog)
     69 __weak_alias(vsyslog,_vsyslog)
     70 #endif
     71 
     72 static int	LogFile = -1;		/* fd for log */
     73 static int	connected;		/* have done connect */
     74 static int	LogStat = 0;		/* status bits, set by openlog() */
     75 static const char *LogTag = NULL;	/* string to tag the entry with */
     76 static int	LogFacility = LOG_USER;	/* default facility code */
     77 static int	LogMask = 0xff;		/* mask of priorities to be logged */
     78 
     79 static void	openlog_unlocked __P((const char *, int, int));
     80 static void	closelog_unlocked __P((void));
     81 
     82 #ifdef _REENT
     83 static mutex_t	syslog_mutex = MUTEX_INITIALIZER;
     84 #endif
     85 
     86 #ifdef lint
     87 static const int ZERO = 0;
     88 #else
     89 #define ZERO	0
     90 #endif
     91 
     92 /*
     93  * syslog, vsyslog --
     94  *	print message on log file; output is intended for syslogd(8).
     95  */
     96 void
     97 syslog(int pri, const char *fmt, ...)
     98 {
     99 	va_list ap;
    100 
    101 	va_start(ap, fmt);
    102 	vsyslog(pri, fmt, ap);
    103 	va_end(ap);
    104 }
    105 
    106 void
    107 vsyslog(pri, fmt, ap)
    108 	int pri;
    109 	const char *fmt;
    110 	_BSD_VA_LIST_ ap;
    111 {
    112 	size_t cnt;
    113 	char ch, *p, *t;
    114 	time_t now;
    115 	struct tm tmnow;
    116 	int fd, saved_errno, tries;
    117 #define	TBUF_LEN	2048
    118 #define	FMT_LEN		1024
    119 	char *stdp = NULL;	/* pacify gcc */
    120 	char tbuf[TBUF_LEN], fmt_cpy[FMT_LEN];
    121 	size_t tbuf_left, fmt_left, prlen;
    122 
    123 #define	INTERNALLOG	LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
    124 	/* Check for invalid bits. */
    125 	if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) {
    126 		syslog(INTERNALLOG,
    127 		    "syslog: unknown facility/priority: %x", pri);
    128 		pri &= LOG_PRIMASK|LOG_FACMASK;
    129 	}
    130 
    131 	/* Check priority against setlogmask values. */
    132 	if (!(LOG_MASK(LOG_PRI(pri)) & LogMask))
    133 		return;
    134 
    135 	saved_errno = errno;
    136 
    137 	/* Set default facility if none specified. */
    138 	if ((pri & LOG_FACMASK) == 0)
    139 		pri |= LogFacility;
    140 
    141 	/* Build the message. */
    142 
    143 	/*
    144  	 * Although it's tempting, we can't ignore the possibility of
    145 	 * overflowing the buffer when assembling the "fixed" portion
    146 	 * of the message.  Strftime's "%h" directive expands to the
    147 	 * locale's abbreviated month name, but if the user has the
    148 	 * ability to construct to his own locale files, it may be
    149 	 * arbitrarily long.
    150 	 */
    151 	(void)time(&now);
    152 
    153 	p = tbuf;
    154 	tbuf_left = TBUF_LEN;
    155 
    156 #define	DEC()							\
    157 	do {							\
    158 		if (prlen >= tbuf_left)				\
    159 			prlen = tbuf_left - 1;			\
    160 		p += prlen;					\
    161 		tbuf_left -= prlen;				\
    162 	} while (ZERO)
    163 
    164 	prlen = snprintf(p, tbuf_left, "<%d>", pri);
    165 	DEC();
    166 
    167 	tzset(); /* strftime() implies tzset(), localtime_r() doesn't. */
    168 	prlen = strftime(p, tbuf_left, "%h %e %T ", localtime_r(&now, &tmnow));
    169 	DEC();
    170 
    171 	if (LogStat & LOG_PERROR)
    172 		stdp = p;
    173 	if (LogTag == NULL)
    174 		LogTag = getprogname();
    175 	if (LogTag != NULL) {
    176 		prlen = snprintf(p, tbuf_left, "%s", LogTag);
    177 		DEC();
    178 	}
    179 	if (LogStat & LOG_PID) {
    180 		prlen = snprintf(p, tbuf_left, "[%d]", getpid());
    181 		DEC();
    182 	}
    183 	if (LogTag != NULL) {
    184 		if (tbuf_left > 1) {
    185 			*p++ = ':';
    186 			tbuf_left--;
    187 		}
    188 		if (tbuf_left > 1) {
    189 			*p++ = ' ';
    190 			tbuf_left--;
    191 		}
    192 	}
    193 
    194 	/*
    195 	 * We wouldn't need this mess if printf handled %m, or if
    196 	 * strerror() had been invented before syslog().
    197 	 */
    198 	for (t = fmt_cpy, fmt_left = FMT_LEN; (ch = *fmt) != '\0'; ++fmt) {
    199 		if (ch == '%' && fmt[1] == 'm') {
    200 			++fmt;
    201 			prlen = snprintf(t, fmt_left, "%s",
    202 			    strerror(saved_errno));
    203 			if (prlen >= fmt_left)
    204 				prlen = fmt_left - 1;
    205 			t += prlen;
    206 			fmt_left -= prlen;
    207 		} else {
    208 			if (fmt_left > 1) {
    209 				*t++ = ch;
    210 				fmt_left--;
    211 			}
    212 		}
    213 	}
    214 	*t = '\0';
    215 
    216 	prlen = vsnprintf(p, tbuf_left, fmt_cpy, ap);
    217 	DEC();
    218 	cnt = p - tbuf;
    219 
    220 	/* Output to stderr if requested. */
    221 	if (LogStat & LOG_PERROR) {
    222 		struct iovec iov[2];
    223 
    224 		iov[0].iov_base = stdp;
    225 		iov[0].iov_len = cnt - (stdp - tbuf);
    226 		iov[1].iov_base = "\n";
    227 		iov[1].iov_len = 1;
    228 		(void)writev(STDERR_FILENO, iov, 2);
    229 	}
    230 
    231 	/* Get connected, output the message to the local logger. */
    232 	mutex_lock(&syslog_mutex);
    233 	/*
    234 	 * Try to send it twice.  If the first try fails, we might
    235 	 * be able to simply reconnect and send the message (which
    236 	 * means syslogd was restarted since we connected the first
    237 	 * time).  If the second attempt doesn't work, then something
    238 	 * else is wrong and there's probably not much we can do
    239 	 * here.
    240 	 */
    241 	for (tries = 1; tries <= 2; tries++) {
    242 		if (!connected)
    243 			openlog_unlocked(LogTag, LogStat | LOG_NDELAY, 0);
    244 		if (send(LogFile, tbuf, cnt, 0) >= 0) {
    245 			mutex_unlock(&syslog_mutex);
    246 			return;
    247 		}
    248 		else
    249 			closelog_unlocked();
    250 	}
    251 	mutex_unlock(&syslog_mutex);
    252 
    253 	/*
    254 	 * Output the message to the console; don't worry about blocking,
    255 	 * if console blocks everything will.  Make sure the error reported
    256 	 * is the one from the syslogd failure.
    257 	 */
    258 	if (LogStat & LOG_CONS &&
    259 	    (fd = open(_PATH_CONSOLE, O_WRONLY, 0)) >= 0) {
    260 		struct iovec iov[2];
    261 
    262 		p = strchr(tbuf, '>') + 1;
    263 		iov[0].iov_base = p;
    264 		iov[0].iov_len = cnt - (p - tbuf);
    265 		iov[1].iov_base = "\r\n";
    266 		iov[1].iov_len = 2;
    267 		(void)writev(fd, iov, 2);
    268 		(void)close(fd);
    269 	}
    270 }
    271 
    272 static struct sockaddr_un SyslogAddr;	/* AF_LOCAL address of local logger */
    273 
    274 static void
    275 openlog_unlocked(ident, logstat, logfac)
    276 	const char *ident;
    277 	int logstat, logfac;
    278 {
    279 
    280 	if (ident != NULL)
    281 		LogTag = ident;
    282 	LogStat = logstat;
    283 	if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0)
    284 		LogFacility = logfac;
    285 
    286 	if (LogFile == -1) {
    287 		SyslogAddr.sun_family = AF_LOCAL;
    288 		(void)strncpy(SyslogAddr.sun_path, _PATH_LOG,
    289 		    sizeof(SyslogAddr.sun_path));
    290 		if (LogStat & LOG_NDELAY) {
    291 			if ((LogFile = socket(AF_LOCAL, SOCK_DGRAM, 0)) == -1)
    292 				return;
    293 			(void)fcntl(LogFile, F_SETFD, 1);
    294 		}
    295 	}
    296 	if (LogFile != -1 && !connected) {
    297 		if (connect(LogFile, (struct sockaddr *)(void *)&SyslogAddr,
    298 		    SUN_LEN(&SyslogAddr)) == -1) {
    299 			(void)close(LogFile);
    300 			LogFile = -1;
    301 		} else
    302 			connected = 1;
    303 	}
    304 }
    305 
    306 void
    307 openlog(ident, logstat, logfac)
    308 	const char *ident;
    309 	int logstat, logfac;
    310 {
    311 
    312 	mutex_lock(&syslog_mutex);
    313 	openlog_unlocked(ident, logstat, logfac);
    314 	mutex_unlock(&syslog_mutex);
    315 }
    316 
    317 static void
    318 closelog_unlocked()
    319 {
    320 	(void)close(LogFile);
    321 	LogFile = -1;
    322 	connected = 0;
    323 }
    324 
    325 void
    326 closelog()
    327 {
    328 
    329 	mutex_lock(&syslog_mutex);
    330 	closelog_unlocked();
    331 	mutex_unlock(&syslog_mutex);
    332 }
    333 
    334 /* setlogmask -- set the log mask level */
    335 int
    336 setlogmask(pmask)
    337 	int pmask;
    338 {
    339 	int omask;
    340 
    341 	omask = LogMask;
    342 	if (pmask != 0)
    343 		LogMask = pmask;
    344 	return (omask);
    345 }
    346