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syslog.c revision 1.38 
      1 /*	$NetBSD: syslog.c,v 1.38 2006/11/05 04:35:35 christos 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 1.38 2006/11/05 04:35:35 christos 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 
     67 __weak_alias(closelog_r,_closelog_r)
     68 __weak_alias(openlog_r,_openlog_r)
     69 __weak_alias(setlogmask_r,_setlogmask_r)
     70 __weak_alias(syslog_r,_syslog_r)
     71 __weak_alias(vsyslog_r,_vsyslog_r)
     72 __weak_alias(syslog_ss,_syslog_ss)
     73 __weak_alias(vsyslog_ss,_vsyslog_ss)
     74 #endif
     75 
     76 static struct syslog_data sdata = SYSLOG_DATA_INIT;
     77 
     78 static void	openlog_unlocked_r(const char *, int, int,
     79     struct syslog_data *);
     80 static void	disconnectlog_r(struct syslog_data *);
     81 static void	connectlog_r(struct syslog_data *);
     82 
     83 #define LOG_SIGNAL_SAFE	(int)0x80000000
     84 
     85 
     86 #ifdef _REENTRANT
     87 static mutex_t	syslog_mutex = MUTEX_INITIALIZER;
     88 #endif
     89 
     90 /*
     91  * syslog, vsyslog --
     92  *	print message on log file; output is intended for syslogd(8).
     93  */
     94 void
     95 syslog(int pri, const char *fmt, ...)
     96 {
     97 	va_list ap;
     98 
     99 	va_start(ap, fmt);
    100 	vsyslog(pri, fmt, ap);
    101 	va_end(ap);
    102 }
    103 
    104 void
    105 vsyslog(int pri, const char *fmt, va_list ap)
    106 {
    107 	vsyslog_r(pri, &sdata, fmt, ap);
    108 }
    109 
    110 void
    111 openlog(const char *ident, int logstat, int logfac)
    112 {
    113 	openlog_r(ident, logstat, logfac, &sdata);
    114 }
    115 
    116 void
    117 closelog(void)
    118 {
    119 	closelog_r(&sdata);
    120 }
    121 
    122 /* setlogmask -- set the log mask level */
    123 int
    124 setlogmask(int pmask)
    125 {
    126 	return setlogmask_r(pmask, &sdata);
    127 }
    128 
    129 /* Reentrant version of syslog, i.e. syslog_r() */
    130 
    131 void
    132 syslog_r(int pri, struct syslog_data *data, const char *fmt, ...)
    133 {
    134 	va_list ap;
    135 
    136 	va_start(ap, fmt);
    137 	vsyslog_r(pri, data, fmt, ap);
    138 	va_end(ap);
    139 }
    140 
    141 void
    142 syslog_ss(int pri, struct syslog_data *data, const char *fmt, ...)
    143 {
    144 	va_list ap;
    145 
    146 	va_start(ap, fmt);
    147 	vsyslog_r(pri | LOG_SIGNAL_SAFE, data, fmt, ap);
    148 	va_end(ap);
    149 }
    150 
    151 void
    152 vsyslog_ss(int pri, struct syslog_data *data, const char *fmt, va_list ap)
    153 {
    154 	vsyslog_r(pri | LOG_SIGNAL_SAFE, data, fmt, ap);
    155 }
    156 
    157 void
    158 vsyslog_r(int pri, struct syslog_data *data, const char *fmt, va_list ap)
    159 {
    160 	size_t cnt, prlen;
    161 	char ch, *p, *t;
    162 	time_t now;
    163 	struct tm tmnow;
    164 	int fd, saved_errno;
    165 #define	TBUF_LEN	2048
    166 #define	FMT_LEN		1024
    167 	char *stdp = NULL;	/* pacify gcc */
    168 	char tbuf[TBUF_LEN], fmt_cpy[FMT_LEN];
    169 	size_t tbuf_left, fmt_left;
    170 	int signal_safe = pri & LOG_SIGNAL_SAFE;
    171 
    172 	pri &= ~LOG_SIGNAL_SAFE;
    173 
    174 #define	INTERNALLOG	LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
    175 	/* Check for invalid bits. */
    176 	if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) {
    177 		syslog_r(INTERNALLOG | signal_safe, data,
    178 		    "syslog_r: unknown facility/priority: %x", pri);
    179 		pri &= LOG_PRIMASK|LOG_FACMASK;
    180 	}
    181 
    182 	/* Check priority against setlogmask values. */
    183 	if (!(LOG_MASK(LOG_PRI(pri)) & data->log_mask))
    184 		return;
    185 
    186 	saved_errno = errno;
    187 
    188 	/* Set default facility if none specified. */
    189 	if ((pri & LOG_FACMASK) == 0)
    190 		pri |= data->log_fac;
    191 
    192 	/* Build the message. */
    193 
    194 	/*
    195  	 * Although it's tempting, we can't ignore the possibility of
    196 	 * overflowing the buffer when assembling the "fixed" portion
    197 	 * of the message.  Strftime's "%h" directive expands to the
    198 	 * locale's abbreviated month name, but if the user has the
    199 	 * ability to construct to his own locale files, it may be
    200 	 * arbitrarily long.
    201 	 */
    202 	 if (!signal_safe)
    203 		(void)time(&now);
    204 
    205 	p = tbuf;
    206 	tbuf_left = TBUF_LEN;
    207 
    208 #define	DEC()							\
    209 	do {							\
    210 		if (prlen >= tbuf_left)				\
    211 			prlen = tbuf_left - 1;			\
    212 		p += prlen;					\
    213 		tbuf_left -= prlen;				\
    214 	} while (/*CONSTCOND*/0)
    215 
    216 	prlen = snprintf_ss(p, tbuf_left, "<%d>", pri);
    217 	DEC();
    218 
    219 	if (!signal_safe) {
    220 		/* strftime() implies tzset(), localtime_r() doesn't. */
    221 		tzset();
    222 		prlen = strftime(p, tbuf_left, "%h %e %T ",
    223 		    localtime_r(&now, &tmnow));
    224 		DEC();
    225 	}
    226 
    227 	if (data->log_stat & LOG_PERROR)
    228 		stdp = p;
    229 	if (data->log_tag == NULL)
    230 		data->log_tag = getprogname();
    231 	if (data->log_tag != NULL) {
    232 		prlen = snprintf_ss(p, tbuf_left, "%s", data->log_tag);
    233 		DEC();
    234 	}
    235 	if (data->log_stat & LOG_PID) {
    236 		prlen = snprintf_ss(p, tbuf_left, "[%d]", getpid());
    237 		DEC();
    238 	}
    239 	if (data->log_tag != NULL) {
    240 		if (tbuf_left > 1) {
    241 			*p++ = ':';
    242 			tbuf_left--;
    243 		}
    244 		if (tbuf_left > 1) {
    245 			*p++ = ' ';
    246 			tbuf_left--;
    247 		}
    248 	}
    249 
    250 	/*
    251 	 * We wouldn't need this mess if printf handled %m, or if
    252 	 * strerror() had been invented before syslog().
    253 	 */
    254 	for (t = fmt_cpy, fmt_left = FMT_LEN; (ch = *fmt) != '\0'; ++fmt) {
    255 		if (ch == '%' && fmt[1] == 'm') {
    256 			char ebuf[128];
    257 			++fmt;
    258 			if (signal_safe ||
    259 			    strerror_r(saved_errno, ebuf, sizeof(ebuf)))
    260 				prlen = snprintf_ss(t, fmt_left, "Error %d",
    261 				    saved_errno);
    262 			else
    263 				prlen = snprintf_ss(t, fmt_left, "%s", ebuf);
    264 			if (prlen >= fmt_left)
    265 				prlen = fmt_left - 1;
    266 			t += prlen;
    267 			fmt_left -= prlen;
    268 		} else if (ch == '%' && fmt[1] == '%' && fmt_left > 2) {
    269 			*t++ = '%';
    270 			*t++ = '%';
    271 			fmt++;
    272 			fmt_left -= 2;
    273 		} else {
    274 			if (fmt_left > 1) {
    275 				*t++ = ch;
    276 				fmt_left--;
    277 			}
    278 		}
    279 	}
    280 	*t = '\0';
    281 
    282 	if (signal_safe)
    283 		prlen = vsnprintf_ss(p, tbuf_left, fmt_cpy, ap);
    284 	else
    285 		prlen = vsnprintf(p, tbuf_left, fmt_cpy, ap);
    286 	DEC();
    287 	cnt = p - tbuf;
    288 
    289 	/* Output to stderr if requested. */
    290 	if (data->log_stat & LOG_PERROR) {
    291 		struct iovec iov[2];
    292 
    293 		iov[0].iov_base = stdp;
    294 		iov[0].iov_len = cnt - (stdp - tbuf);
    295 		iov[1].iov_base = __UNCONST("\n");
    296 		iov[1].iov_len = 1;
    297 		(void)writev(STDERR_FILENO, iov, 2);
    298 	}
    299 
    300 	/* Get connected, output the message to the local logger. */
    301 	if (data == &sdata)
    302 		mutex_lock(&syslog_mutex);
    303 	if (!data->opened)
    304 		openlog_unlocked_r(data->log_tag, data->log_stat, 0, data);
    305 	connectlog_r(data);
    306 
    307 	/*
    308 	 * If the send() failed, there are two likely scenarios:
    309 	 *  1) syslogd was restarted
    310 	 *  2) /dev/log is out of socket buffer space
    311 	 * We attempt to reconnect to /dev/log to take care of
    312 	 * case #1 and keep send()ing data to cover case #2
    313 	 * to give syslogd a chance to empty its socket buffer.
    314 	 */
    315 	if (send(data->log_file, tbuf, cnt, 0) == -1) {
    316 		if (errno != ENOBUFS) {
    317 			disconnectlog_r(data);
    318 			connectlog_r(data);
    319 		}
    320 		do {
    321 			usleep(1);
    322 			if (send(data->log_file, tbuf, cnt, 0) != -1)
    323 				break;
    324 		} while (errno == ENOBUFS);
    325 	}
    326 	if (data == &sdata)
    327 		mutex_unlock(&syslog_mutex);
    328 
    329 	/*
    330 	 * Output the message to the console; try not to block
    331 	 * as a blocking console should not stop other processes.
    332 	 * Make sure the error reported is the one from the syslogd failure.
    333 	 */
    334 	if ((data->log_stat & LOG_CONS) &&
    335 	    (fd = open(_PATH_CONSOLE, O_WRONLY|O_NONBLOCK, 0)) >= 0) {
    336 		struct iovec iov[2];
    337 
    338 		p = strchr(tbuf, '>') + 1;
    339 		iov[0].iov_base = p;
    340 		iov[0].iov_len = cnt - (p - tbuf);
    341 		iov[1].iov_base = __UNCONST("\r\n");
    342 		iov[1].iov_len = 2;
    343 		(void)writev(fd, iov, 2);
    344 		(void)close(fd);
    345 	}
    346 	if (data != &sdata)
    347 		closelog_r(data);
    348 }
    349 
    350 static void
    351 disconnectlog_r(struct syslog_data *data)
    352 {
    353 	/*
    354 	 * If the user closed the FD and opened another in the same slot,
    355 	 * that's their problem.  They should close it before calling on
    356 	 * system services.
    357 	 */
    358 	if (data->log_file != -1) {
    359 		(void)close(data->log_file);
    360 		data->log_file = -1;
    361 	}
    362 	data->connected = 0;		/* retry connect */
    363 }
    364 
    365 static void
    366 connectlog_r(struct syslog_data *data)
    367 {
    368 	/* AF_UNIX address of local logger */
    369 	static const struct sockaddr_un sun = {
    370 		.sun_family = AF_LOCAL,
    371 		.sun_len = sizeof(sun),
    372 		.sun_path = _PATH_LOG,
    373 	};
    374 
    375 	if (data->log_file == -1 || fcntl(data->log_file, F_GETFL, 0) == -1) {
    376 		if ((data->log_file = socket(AF_UNIX, SOCK_DGRAM, 0)) == -1)
    377 			return;
    378 		(void)fcntl(data->log_file, F_SETFD, FD_CLOEXEC);
    379 		data->connected = 0;
    380 	}
    381 	if (!data->connected) {
    382 		if (connect(data->log_file,
    383 		    (const struct sockaddr *)(const void *)&sun,
    384 		    sizeof(sun)) == -1) {
    385 			(void)close(data->log_file);
    386 			data->log_file = -1;
    387  		} else
    388 			data->connected = 1;
    389 	}
    390 }
    391 
    392 static void
    393 openlog_unlocked_r(const char *ident, int logstat, int logfac,
    394     struct syslog_data *data)
    395 {
    396 	if (ident != NULL)
    397 		data->log_tag = ident;
    398 	data->log_stat = logstat;
    399 	if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0)
    400 		data->log_fac = logfac;
    401 
    402 	if (data->log_stat & LOG_NDELAY)	/* open immediately */
    403 		connectlog_r(data);
    404 }
    405 
    406 void
    407 openlog_r(const char *ident, int logstat, int logfac, struct syslog_data *data)
    408 {
    409 	if (data == &sdata)
    410 		mutex_lock(&syslog_mutex);
    411 	openlog_unlocked_r(ident, logstat, logfac, data);
    412 	if (data == &sdata)
    413 		mutex_unlock(&syslog_mutex);
    414 }
    415 
    416 void
    417 closelog_r(struct syslog_data *data)
    418 {
    419 	if (data == &sdata)
    420 		mutex_lock(&syslog_mutex);
    421 	(void)close(data->log_file);
    422 	data->log_file = -1;
    423 	data->connected = 0;
    424 	data->log_tag = NULL;
    425 	if (data == &sdata)
    426 		mutex_unlock(&syslog_mutex);
    427 }
    428 
    429 int
    430 setlogmask_r(int pmask, struct syslog_data *data)
    431 {
    432 	int omask;
    433 
    434 	omask = data->log_mask;
    435 	if (pmask != 0)
    436 		data->log_mask = pmask;
    437 	return omask;
    438 }
    439