xref: /src/lib/libc/gen/syslog.c

/*	$NetBSD: syslog.c,v 1.31 2005/11/29 03:11:59 christos Exp $	*/

/*
 * Copyright (c) 1983, 1988, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)syslog.c	8.5 (Berkeley) 4/29/95";
#else
__RCSID("$NetBSD: syslog.c,v 1.31 2005/11/29 03:11:59 christos Exp $");
#endif
#endif /* LIBC_SCCS and not lint */

#include "namespace.h"
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/syslog.h>
#include <sys/uio.h>
#include <sys/un.h>
#include <netdb.h>

#include <errno.h>
#include <fcntl.h>
#include <paths.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include "reentrant.h"

#ifdef __weak_alias
__weak_alias(closelog,_closelog)
__weak_alias(openlog,_openlog)
__weak_alias(setlogmask,_setlogmask)
__weak_alias(syslog,_syslog)
__weak_alias(vsyslog,_vsyslog)
#endif

static int	LogFile = -1;		/* fd for log */
static int	connected;		/* have done connect */
static int	LogStat = 0;		/* status bits, set by openlog() */
static const char *LogTag = NULL;	/* string to tag the entry with */
static int	LogFacility = LOG_USER;	/* default facility code */
static int	LogMask = 0xff;		/* mask of priorities to be logged */

static void	openlog_unlocked __P((const char *, int, int));
static void	closelog_unlocked __P((void));

#ifdef _REENTRANT
static mutex_t	syslog_mutex = MUTEX_INITIALIZER;
#endif

#ifdef lint
static const int ZERO = 0;
#else
#define ZERO	0
#endif

/*
 * syslog, vsyslog --
 *	print message on log file; output is intended for syslogd(8).
 */
void
syslog(int pri, const char *fmt, ...)
{
	va_list ap;

	va_start(ap, fmt);
	vsyslog(pri, fmt, ap);
	va_end(ap);
}

void
vsyslog(pri, fmt, ap)
	int pri;
	const char *fmt;
	_BSD_VA_LIST_ ap;
{
	size_t cnt;
	char ch, *p, *t;
	time_t now;
	struct tm tmnow;
	int fd, saved_errno, tries;
#define	TBUF_LEN	2048
#define	FMT_LEN		1024
	char *stdp = NULL;	/* pacify gcc */
	char tbuf[TBUF_LEN], fmt_cpy[FMT_LEN];
	size_t tbuf_left, fmt_left, prlen;

#define	INTERNALLOG	LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
	/* Check for invalid bits. */
	if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) {
		syslog(INTERNALLOG,
		    "syslog: unknown facility/priority: %x", pri);
		pri &= LOG_PRIMASK|LOG_FACMASK;
	}

	/* Check priority against setlogmask values. */
	if (!(LOG_MASK(LOG_PRI(pri)) & LogMask))
		return;

	saved_errno = errno;

	/* Set default facility if none specified. */
	if ((pri & LOG_FACMASK) == 0)
		pri |= LogFacility;

	/* Build the message. */

	/*
 	 * Although it's tempting, we can't ignore the possibility of
	 * overflowing the buffer when assembling the "fixed" portion
	 * of the message.  Strftime's "%h" directive expands to the
	 * locale's abbreviated month name, but if the user has the
	 * ability to construct to his own locale files, it may be
	 * arbitrarily long.
	 */
	(void)time(&now);

	p = tbuf;
	tbuf_left = TBUF_LEN;

#define	DEC()							\
	do {							\
		if (prlen >= tbuf_left)				\
			prlen = tbuf_left - 1;			\
		p += prlen;					\
		tbuf_left -= prlen;				\
	} while (ZERO)

	prlen = snprintf(p, tbuf_left, "<%d>", pri);
	DEC();

	tzset(); /* strftime() implies tzset(), localtime_r() doesn't. */
	prlen = strftime(p, tbuf_left, "%h %e %T ", localtime_r(&now, &tmnow));
	DEC();

	if (LogStat & LOG_PERROR)
		stdp = p;
	if (LogTag == NULL)
		LogTag = getprogname();
	if (LogTag != NULL) {
		prlen = snprintf(p, tbuf_left, "%s", LogTag);
		DEC();
	}
	if (LogStat & LOG_PID) {
		prlen = snprintf(p, tbuf_left, "[%d]", getpid());
		DEC();
	}
	if (LogTag != NULL) {
		if (tbuf_left > 1) {
			*p++ = ':';
			tbuf_left--;
		}
		if (tbuf_left > 1) {
			*p++ = ' ';
			tbuf_left--;
		}
	}

	/*
	 * We wouldn't need this mess if printf handled %m, or if
	 * strerror() had been invented before syslog().
	 */
	for (t = fmt_cpy, fmt_left = FMT_LEN; (ch = *fmt) != '\0'; ++fmt) {
		if (ch == '%' && fmt[1] == 'm') {
			++fmt;
			prlen = snprintf(t, fmt_left, "%s",
			    strerror(saved_errno));
			if (prlen >= fmt_left)
				prlen = fmt_left - 1;
			t += prlen;
			fmt_left -= prlen;
		} else {
			if (fmt_left > 1) {
				*t++ = ch;
				fmt_left--;
			}
		}
	}
	*t = '\0';

	prlen = vsnprintf(p, tbuf_left, fmt_cpy, ap);
	DEC();
	cnt = p - tbuf;

	/* Output to stderr if requested. */
	if (LogStat & LOG_PERROR) {
		struct iovec iov[2];

		iov[0].iov_base = stdp;
		iov[0].iov_len = cnt - (stdp - tbuf);
		iov[1].iov_base = __UNCONST("\n");
		iov[1].iov_len = 1;
		(void)writev(STDERR_FILENO, iov, 2);
	}

	/* Get connected, output the message to the local logger. */
	mutex_lock(&syslog_mutex);
	/*
	 * Try to send it twice.  If the first try fails, we might
	 * be able to simply reconnect and send the message (which
	 * means syslogd was restarted since we connected the first
	 * time).  If the second attempt doesn't work, then something
	 * else is wrong and there's probably not much we can do
	 * here.
	 */
	for (tries = 1; tries <= 2; tries++) {
		if (!connected)
			openlog_unlocked(LogTag, LogStat | LOG_NDELAY, 0);
		if (send(LogFile, tbuf, cnt, 0) >= 0) {
			mutex_unlock(&syslog_mutex);
			return;
		}
		else
			closelog_unlocked();
	}
	mutex_unlock(&syslog_mutex);

	/*
	 * Output the message to the console; don't worry about blocking,
	 * if console blocks everything will.  Make sure the error reported
	 * is the one from the syslogd failure.
	 */
	if (LogStat & LOG_CONS &&
	    (fd = open(_PATH_CONSOLE, O_WRONLY, 0)) >= 0) {
		struct iovec iov[2];

		p = strchr(tbuf, '>') + 1;
		iov[0].iov_base = p;
		iov[0].iov_len = cnt - (p - tbuf);
		iov[1].iov_base = __UNCONST("\r\n");
		iov[1].iov_len = 2;
		(void)writev(fd, iov, 2);
		(void)close(fd);
	}
}

static struct sockaddr_un SyslogAddr;	/* AF_LOCAL address of local logger */

static void
openlog_unlocked(ident, logstat, logfac)
	const char *ident;
	int logstat, logfac;
{

	if (ident != NULL)
		LogTag = ident;
	LogStat = logstat;
	if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0)
		LogFacility = logfac;

	if (LogFile == -1) {
		SyslogAddr.sun_family = AF_LOCAL;
		(void)strncpy(SyslogAddr.sun_path, _PATH_LOG,
		    sizeof(SyslogAddr.sun_path));
		if (LogStat & LOG_NDELAY) {
			if ((LogFile = socket(AF_LOCAL, SOCK_DGRAM, 0)) == -1)
				return;
			(void)fcntl(LogFile, F_SETFD, 1);
		}
	}
	if (LogFile != -1 && !connected) {
		if (connect(LogFile, (struct sockaddr *)(void *)&SyslogAddr,
		    SUN_LEN(&SyslogAddr)) == -1) {
			(void)close(LogFile);
			LogFile = -1;
		} else
			connected = 1;
	}
}

void
openlog(ident, logstat, logfac)
	const char *ident;
	int logstat, logfac;
{

	mutex_lock(&syslog_mutex);
	openlog_unlocked(ident, logstat, logfac);
	mutex_unlock(&syslog_mutex);
}

static void
closelog_unlocked()
{
	(void)close(LogFile);
	LogFile = -1;
	connected = 0;
}

void
closelog()
{

	mutex_lock(&syslog_mutex);
	closelog_unlocked();
	mutex_unlock(&syslog_mutex);
}

/* setlogmask -- set the log mask level */
int
setlogmask(pmask)
	int pmask;
{
	int omask;

	omask = LogMask;
	if (pmask != 0)
		LogMask = pmask;
	return (omask);
}