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syslog.c revision 1.27 
      1 /*	$NetBSD: syslog.c,v 1.27 2001/07/30 04:12:33 atatat 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 1.27 2001/07/30 04:12:33 atatat 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 <stdio.h>
     57 #include <stdlib.h>
     58 #include <string.h>
     59 #include <time.h>
     60 #include <unistd.h>
     61 #include "reentrant.h"
     62 
     63 #if __STDC__
     64 #include <stdarg.h>
     65 #else
     66 #include <varargs.h>
     67 #endif
     68 
     69 #ifdef __weak_alias
     70 __weak_alias(closelog,_closelog)
     71 __weak_alias(openlog,_openlog)
     72 __weak_alias(setlogmask,_setlogmask)
     73 __weak_alias(syslog,_syslog)
     74 __weak_alias(vsyslog,_vsyslog)
     75 #endif
     76 
     77 static int	LogFile = -1;		/* fd for log */
     78 static int	connected;		/* have done connect */
     79 static int	LogStat = 0;		/* status bits, set by openlog() */
     80 static const char *LogTag = NULL;	/* string to tag the entry with */
     81 static int	LogFacility = LOG_USER;	/* default facility code */
     82 static int	LogMask = 0xff;		/* mask of priorities to be logged */
     83 
     84 static void	openlog_unlocked __P((const char *, int, int));
     85 static void	closelog_unlocked __P((void));
     86 
     87 #ifdef _REENT
     88 static mutex_t	syslog_mutex = MUTEX_INITIALIZER;
     89 #endif
     90 
     91 #ifdef lint
     92 static const int ZERO = 0;
     93 #else
     94 #define ZERO	0
     95 #endif
     96 
     97 /*
     98  * syslog, vsyslog --
     99  *	print message on log file; output is intended for syslogd(8).
    100  */
    101 void
    102 #if __STDC__
    103 syslog(int pri, const char *fmt, ...)
    104 #else
    105 syslog(pri, fmt, va_alist)
    106 	int pri;
    107 	char *fmt;
    108 	va_dcl
    109 #endif
    110 {
    111 	va_list ap;
    112 
    113 #if __STDC__
    114 	va_start(ap, fmt);
    115 #else
    116 	va_start(ap);
    117 #endif
    118 	vsyslog(pri, fmt, ap);
    119 	va_end(ap);
    120 }
    121 
    122 void
    123 vsyslog(pri, fmt, ap)
    124 	int pri;
    125 	const char *fmt;
    126 	_BSD_VA_LIST_ ap;
    127 {
    128 	size_t cnt;
    129 	char ch, *p, *t;
    130 	time_t now;
    131 	struct tm tmnow;
    132 	int fd, saved_errno, tries;
    133 #define	TBUF_LEN	2048
    134 #define	FMT_LEN		1024
    135 	char *stdp = NULL;	/* pacify gcc */
    136 	char tbuf[TBUF_LEN], fmt_cpy[FMT_LEN];
    137 	size_t tbuf_left, fmt_left, prlen;
    138 
    139 #define	INTERNALLOG	LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
    140 	/* Check for invalid bits. */
    141 	if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) {
    142 		syslog(INTERNALLOG,
    143 		    "syslog: unknown facility/priority: %x", pri);
    144 		pri &= LOG_PRIMASK|LOG_FACMASK;
    145 	}
    146 
    147 	/* Check priority against setlogmask values. */
    148 	if (!(LOG_MASK(LOG_PRI(pri)) & LogMask))
    149 		return;
    150 
    151 	saved_errno = errno;
    152 
    153 	/* Set default facility if none specified. */
    154 	if ((pri & LOG_FACMASK) == 0)
    155 		pri |= LogFacility;
    156 
    157 	/* Build the message. */
    158 
    159 	/*
    160  	 * Although it's tempting, we can't ignore the possibility of
    161 	 * overflowing the buffer when assembling the "fixed" portion
    162 	 * of the message.  Strftime's "%h" directive expands to the
    163 	 * locale's abbreviated month name, but if the user has the
    164 	 * ability to construct to his own locale files, it may be
    165 	 * arbitrarily long.
    166 	 */
    167 	(void)time(&now);
    168 
    169 	p = tbuf;
    170 	tbuf_left = TBUF_LEN;
    171 
    172 #define	DEC()							\
    173 	do {							\
    174 		if (prlen >= tbuf_left)				\
    175 			prlen = tbuf_left - 1;			\
    176 		p += prlen;					\
    177 		tbuf_left -= prlen;				\
    178 	} while (ZERO)
    179 
    180 	prlen = snprintf(p, tbuf_left, "<%d>", pri);
    181 	DEC();
    182 
    183 	tzset(); /* strftime() implies tzset(), localtime_r() doesn't. */
    184 	prlen = strftime(p, tbuf_left, "%h %e %T ", localtime_r(&now, &tmnow));
    185 	DEC();
    186 
    187 	if (LogStat & LOG_PERROR)
    188 		stdp = p;
    189 	if (LogTag == NULL)
    190 		LogTag = getprogname();
    191 	if (LogTag != NULL) {
    192 		prlen = snprintf(p, tbuf_left, "%s", LogTag);
    193 		DEC();
    194 	}
    195 	if (LogStat & LOG_PID) {
    196 		prlen = snprintf(p, tbuf_left, "[%d]", getpid());
    197 		DEC();
    198 	}
    199 	if (LogTag != NULL) {
    200 		if (tbuf_left > 1) {
    201 			*p++ = ':';
    202 			tbuf_left--;
    203 		}
    204 		if (tbuf_left > 1) {
    205 			*p++ = ' ';
    206 			tbuf_left--;
    207 		}
    208 	}
    209 
    210 	/*
    211 	 * We wouldn't need this mess if printf handled %m, or if
    212 	 * strerror() had been invented before syslog().
    213 	 */
    214 	for (t = fmt_cpy, fmt_left = FMT_LEN; (ch = *fmt) != '\0'; ++fmt) {
    215 		if (ch == '%' && fmt[1] == 'm') {
    216 			++fmt;
    217 			prlen = snprintf(t, fmt_left, "%s",
    218 			    strerror(saved_errno));
    219 			if (prlen >= fmt_left)
    220 				prlen = fmt_left - 1;
    221 			t += prlen;
    222 			fmt_left -= prlen;
    223 		} else {
    224 			if (fmt_left > 1) {
    225 				*t++ = ch;
    226 				fmt_left--;
    227 			}
    228 		}
    229 	}
    230 	*t = '\0';
    231 
    232 	prlen = vsnprintf(p, tbuf_left, fmt_cpy, ap);
    233 	DEC();
    234 	cnt = p - tbuf;
    235 
    236 	/* Output to stderr if requested. */
    237 	if (LogStat & LOG_PERROR) {
    238 		struct iovec iov[2];
    239 
    240 		iov[0].iov_base = stdp;
    241 		iov[0].iov_len = cnt - (stdp - tbuf);
    242 		iov[1].iov_base = "\n";
    243 		iov[1].iov_len = 1;
    244 		(void)writev(STDERR_FILENO, iov, 2);
    245 	}
    246 
    247 	/* Get connected, output the message to the local logger. */
    248 	mutex_lock(&syslog_mutex);
    249 	/*
    250 	 * Try to send it twice.  If the first try fails, we might
    251 	 * be able to simply reconnect and send the message (which
    252 	 * means syslogd was restarted since we connected the first
    253 	 * time).  If the second attempt doesn't work, then something
    254 	 * else is wrong and there's probably not much we can do
    255 	 * here.
    256 	 */
    257 	for (tries = 1; tries <= 2; tries++) {
    258 		if (!connected)
    259 			openlog_unlocked(LogTag, LogStat | LOG_NDELAY, 0);
    260 		if (send(LogFile, tbuf, cnt, 0) >= 0) {
    261 			mutex_unlock(&syslog_mutex);
    262 			return;
    263 		}
    264 		else
    265 			closelog_unlocked();
    266 	}
    267 	mutex_unlock(&syslog_mutex);
    268 
    269 	/*
    270 	 * Output the message to the console; don't worry about blocking,
    271 	 * if console blocks everything will.  Make sure the error reported
    272 	 * is the one from the syslogd failure.
    273 	 */
    274 	if (LogStat & LOG_CONS &&
    275 	    (fd = open(_PATH_CONSOLE, O_WRONLY, 0)) >= 0) {
    276 		struct iovec iov[2];
    277 
    278 		p = strchr(tbuf, '>') + 1;
    279 		iov[0].iov_base = p;
    280 		iov[0].iov_len = cnt - (p - tbuf);
    281 		iov[1].iov_base = "\r\n";
    282 		iov[1].iov_len = 2;
    283 		(void)writev(fd, iov, 2);
    284 		(void)close(fd);
    285 	}
    286 }
    287 
    288 static struct sockaddr_un SyslogAddr;	/* AF_LOCAL address of local logger */
    289 
    290 static void
    291 openlog_unlocked(ident, logstat, logfac)
    292 	const char *ident;
    293 	int logstat, logfac;
    294 {
    295 
    296 	if (ident != NULL)
    297 		LogTag = ident;
    298 	LogStat = logstat;
    299 	if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0)
    300 		LogFacility = logfac;
    301 
    302 	if (LogFile == -1) {
    303 		SyslogAddr.sun_family = AF_LOCAL;
    304 		(void)strncpy(SyslogAddr.sun_path, _PATH_LOG,
    305 		    sizeof(SyslogAddr.sun_path));
    306 		if (LogStat & LOG_NDELAY) {
    307 			if ((LogFile = socket(AF_LOCAL, SOCK_DGRAM, 0)) == -1)
    308 				return;
    309 			(void)fcntl(LogFile, F_SETFD, 1);
    310 		}
    311 	}
    312 	if (LogFile != -1 && !connected) {
    313 		if (connect(LogFile, (struct sockaddr *)(void *)&SyslogAddr,
    314 		    SUN_LEN(&SyslogAddr)) == -1) {
    315 			(void)close(LogFile);
    316 			LogFile = -1;
    317 		} else
    318 			connected = 1;
    319 	}
    320 }
    321 
    322 void
    323 openlog(ident, logstat, logfac)
    324 	const char *ident;
    325 	int logstat, logfac;
    326 {
    327 
    328 	mutex_lock(&syslog_mutex);
    329 	openlog_unlocked(ident, logstat, logfac);
    330 	mutex_unlock(&syslog_mutex);
    331 }
    332 
    333 static void
    334 closelog_unlocked()
    335 {
    336 	(void)close(LogFile);
    337 	LogFile = -1;
    338 	connected = 0;
    339 }
    340 
    341 void
    342 closelog()
    343 {
    344 
    345 	mutex_lock(&syslog_mutex);
    346 	closelog_unlocked();
    347 	mutex_unlock(&syslog_mutex);
    348 }
    349 
    350 /* setlogmask -- set the log mask level */
    351 int
    352 setlogmask(pmask)
    353 	int pmask;
    354 {
    355 	int omask;
    356 
    357 	omask = LogMask;
    358 	if (pmask != 0)
    359 		LogMask = pmask;
    360 	return (omask);
    361 }
    362