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syslog.c revision 1.30 
      1 /*	$NetBSD: syslog.c,v 1.30 2003/08/07 16:42:57 agc 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. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #if defined(LIBC_SCCS) && !defined(lint)
     34 #if 0
     35 static char sccsid[] = "@(#)syslog.c	8.5 (Berkeley) 4/29/95";
     36 #else
     37 __RCSID("$NetBSD: syslog.c,v 1.30 2003/08/07 16:42:57 agc Exp $");
     38 #endif
     39 #endif /* LIBC_SCCS and not lint */
     40 
     41 #include "namespace.h"
     42 #include <sys/types.h>
     43 #include <sys/socket.h>
     44 #include <sys/syslog.h>
     45 #include <sys/uio.h>
     46 #include <sys/un.h>
     47 #include <netdb.h>
     48 
     49 #include <errno.h>
     50 #include <fcntl.h>
     51 #include <paths.h>
     52 #include <stdarg.h>
     53 #include <stdio.h>
     54 #include <stdlib.h>
     55 #include <string.h>
     56 #include <time.h>
     57 #include <unistd.h>
     58 #include "reentrant.h"
     59 
     60 #ifdef __weak_alias
     61 __weak_alias(closelog,_closelog)
     62 __weak_alias(openlog,_openlog)
     63 __weak_alias(setlogmask,_setlogmask)
     64 __weak_alias(syslog,_syslog)
     65 __weak_alias(vsyslog,_vsyslog)
     66 #endif
     67 
     68 static int	LogFile = -1;		/* fd for log */
     69 static int	connected;		/* have done connect */
     70 static int	LogStat = 0;		/* status bits, set by openlog() */
     71 static const char *LogTag = NULL;	/* string to tag the entry with */
     72 static int	LogFacility = LOG_USER;	/* default facility code */
     73 static int	LogMask = 0xff;		/* mask of priorities to be logged */
     74 
     75 static void	openlog_unlocked __P((const char *, int, int));
     76 static void	closelog_unlocked __P((void));
     77 
     78 #ifdef _REENTRANT
     79 static mutex_t	syslog_mutex = MUTEX_INITIALIZER;
     80 #endif
     81 
     82 #ifdef lint
     83 static const int ZERO = 0;
     84 #else
     85 #define ZERO	0
     86 #endif
     87 
     88 /*
     89  * syslog, vsyslog --
     90  *	print message on log file; output is intended for syslogd(8).
     91  */
     92 void
     93 syslog(int pri, const char *fmt, ...)
     94 {
     95 	va_list ap;
     96 
     97 	va_start(ap, fmt);
     98 	vsyslog(pri, fmt, ap);
     99 	va_end(ap);
    100 }
    101 
    102 void
    103 vsyslog(pri, fmt, ap)
    104 	int pri;
    105 	const char *fmt;
    106 	_BSD_VA_LIST_ ap;
    107 {
    108 	size_t cnt;
    109 	char ch, *p, *t;
    110 	time_t now;
    111 	struct tm tmnow;
    112 	int fd, saved_errno, tries;
    113 #define	TBUF_LEN	2048
    114 #define	FMT_LEN		1024
    115 	char *stdp = NULL;	/* pacify gcc */
    116 	char tbuf[TBUF_LEN], fmt_cpy[FMT_LEN];
    117 	size_t tbuf_left, fmt_left, prlen;
    118 
    119 #define	INTERNALLOG	LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
    120 	/* Check for invalid bits. */
    121 	if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) {
    122 		syslog(INTERNALLOG,
    123 		    "syslog: unknown facility/priority: %x", pri);
    124 		pri &= LOG_PRIMASK|LOG_FACMASK;
    125 	}
    126 
    127 	/* Check priority against setlogmask values. */
    128 	if (!(LOG_MASK(LOG_PRI(pri)) & LogMask))
    129 		return;
    130 
    131 	saved_errno = errno;
    132 
    133 	/* Set default facility if none specified. */
    134 	if ((pri & LOG_FACMASK) == 0)
    135 		pri |= LogFacility;
    136 
    137 	/* Build the message. */
    138 
    139 	/*
    140  	 * Although it's tempting, we can't ignore the possibility of
    141 	 * overflowing the buffer when assembling the "fixed" portion
    142 	 * of the message.  Strftime's "%h" directive expands to the
    143 	 * locale's abbreviated month name, but if the user has the
    144 	 * ability to construct to his own locale files, it may be
    145 	 * arbitrarily long.
    146 	 */
    147 	(void)time(&now);
    148 
    149 	p = tbuf;
    150 	tbuf_left = TBUF_LEN;
    151 
    152 #define	DEC()							\
    153 	do {							\
    154 		if (prlen >= tbuf_left)				\
    155 			prlen = tbuf_left - 1;			\
    156 		p += prlen;					\
    157 		tbuf_left -= prlen;				\
    158 	} while (ZERO)
    159 
    160 	prlen = snprintf(p, tbuf_left, "<%d>", pri);
    161 	DEC();
    162 
    163 	tzset(); /* strftime() implies tzset(), localtime_r() doesn't. */
    164 	prlen = strftime(p, tbuf_left, "%h %e %T ", localtime_r(&now, &tmnow));
    165 	DEC();
    166 
    167 	if (LogStat & LOG_PERROR)
    168 		stdp = p;
    169 	if (LogTag == NULL)
    170 		LogTag = getprogname();
    171 	if (LogTag != NULL) {
    172 		prlen = snprintf(p, tbuf_left, "%s", LogTag);
    173 		DEC();
    174 	}
    175 	if (LogStat & LOG_PID) {
    176 		prlen = snprintf(p, tbuf_left, "[%d]", getpid());
    177 		DEC();
    178 	}
    179 	if (LogTag != NULL) {
    180 		if (tbuf_left > 1) {
    181 			*p++ = ':';
    182 			tbuf_left--;
    183 		}
    184 		if (tbuf_left > 1) {
    185 			*p++ = ' ';
    186 			tbuf_left--;
    187 		}
    188 	}
    189 
    190 	/*
    191 	 * We wouldn't need this mess if printf handled %m, or if
    192 	 * strerror() had been invented before syslog().
    193 	 */
    194 	for (t = fmt_cpy, fmt_left = FMT_LEN; (ch = *fmt) != '\0'; ++fmt) {
    195 		if (ch == '%' && fmt[1] == 'm') {
    196 			++fmt;
    197 			prlen = snprintf(t, fmt_left, "%s",
    198 			    strerror(saved_errno));
    199 			if (prlen >= fmt_left)
    200 				prlen = fmt_left - 1;
    201 			t += prlen;
    202 			fmt_left -= prlen;
    203 		} else {
    204 			if (fmt_left > 1) {
    205 				*t++ = ch;
    206 				fmt_left--;
    207 			}
    208 		}
    209 	}
    210 	*t = '\0';
    211 
    212 	prlen = vsnprintf(p, tbuf_left, fmt_cpy, ap);
    213 	DEC();
    214 	cnt = p - tbuf;
    215 
    216 	/* Output to stderr if requested. */
    217 	if (LogStat & LOG_PERROR) {
    218 		struct iovec iov[2];
    219 
    220 		iov[0].iov_base = stdp;
    221 		iov[0].iov_len = cnt - (stdp - tbuf);
    222 		iov[1].iov_base = "\n";
    223 		iov[1].iov_len = 1;
    224 		(void)writev(STDERR_FILENO, iov, 2);
    225 	}
    226 
    227 	/* Get connected, output the message to the local logger. */
    228 	mutex_lock(&syslog_mutex);
    229 	/*
    230 	 * Try to send it twice.  If the first try fails, we might
    231 	 * be able to simply reconnect and send the message (which
    232 	 * means syslogd was restarted since we connected the first
    233 	 * time).  If the second attempt doesn't work, then something
    234 	 * else is wrong and there's probably not much we can do
    235 	 * here.
    236 	 */
    237 	for (tries = 1; tries <= 2; tries++) {
    238 		if (!connected)
    239 			openlog_unlocked(LogTag, LogStat | LOG_NDELAY, 0);
    240 		if (send(LogFile, tbuf, cnt, 0) >= 0) {
    241 			mutex_unlock(&syslog_mutex);
    242 			return;
    243 		}
    244 		else
    245 			closelog_unlocked();
    246 	}
    247 	mutex_unlock(&syslog_mutex);
    248 
    249 	/*
    250 	 * Output the message to the console; don't worry about blocking,
    251 	 * if console blocks everything will.  Make sure the error reported
    252 	 * is the one from the syslogd failure.
    253 	 */
    254 	if (LogStat & LOG_CONS &&
    255 	    (fd = open(_PATH_CONSOLE, O_WRONLY, 0)) >= 0) {
    256 		struct iovec iov[2];
    257 
    258 		p = strchr(tbuf, '>') + 1;
    259 		iov[0].iov_base = p;
    260 		iov[0].iov_len = cnt - (p - tbuf);
    261 		iov[1].iov_base = "\r\n";
    262 		iov[1].iov_len = 2;
    263 		(void)writev(fd, iov, 2);
    264 		(void)close(fd);
    265 	}
    266 }
    267 
    268 static struct sockaddr_un SyslogAddr;	/* AF_LOCAL address of local logger */
    269 
    270 static void
    271 openlog_unlocked(ident, logstat, logfac)
    272 	const char *ident;
    273 	int logstat, logfac;
    274 {
    275 
    276 	if (ident != NULL)
    277 		LogTag = ident;
    278 	LogStat = logstat;
    279 	if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0)
    280 		LogFacility = logfac;
    281 
    282 	if (LogFile == -1) {
    283 		SyslogAddr.sun_family = AF_LOCAL;
    284 		(void)strncpy(SyslogAddr.sun_path, _PATH_LOG,
    285 		    sizeof(SyslogAddr.sun_path));
    286 		if (LogStat & LOG_NDELAY) {
    287 			if ((LogFile = socket(AF_LOCAL, SOCK_DGRAM, 0)) == -1)
    288 				return;
    289 			(void)fcntl(LogFile, F_SETFD, 1);
    290 		}
    291 	}
    292 	if (LogFile != -1 && !connected) {
    293 		if (connect(LogFile, (struct sockaddr *)(void *)&SyslogAddr,
    294 		    SUN_LEN(&SyslogAddr)) == -1) {
    295 			(void)close(LogFile);
    296 			LogFile = -1;
    297 		} else
    298 			connected = 1;
    299 	}
    300 }
    301 
    302 void
    303 openlog(ident, logstat, logfac)
    304 	const char *ident;
    305 	int logstat, logfac;
    306 {
    307 
    308 	mutex_lock(&syslog_mutex);
    309 	openlog_unlocked(ident, logstat, logfac);
    310 	mutex_unlock(&syslog_mutex);
    311 }
    312 
    313 static void
    314 closelog_unlocked()
    315 {
    316 	(void)close(LogFile);
    317 	LogFile = -1;
    318 	connected = 0;
    319 }
    320 
    321 void
    322 closelog()
    323 {
    324 
    325 	mutex_lock(&syslog_mutex);
    326 	closelog_unlocked();
    327 	mutex_unlock(&syslog_mutex);
    328 }
    329 
    330 /* setlogmask -- set the log mask level */
    331 int
    332 setlogmask(pmask)
    333 	int pmask;
    334 {
    335 	int omask;
    336 
    337 	omask = LogMask;
    338 	if (pmask != 0)
    339 		LogMask = pmask;
    340 	return (omask);
    341 }
    342