/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ #include <u.h>#include <libc.h> static struct{	int	fd;	int	consfd;	char	*name;	Dir	*d;	Dir	*consd;	Lock;} sl ={	-1, -1,}; static void_syslogopen(void){	char buf[1024]; 	if(sl.fd >= 0)		close(sl.fd);	snprint(buf, sizeof(buf), "/sys/log/%s", sl.name);	sl.fd = open(buf, OWRITE|OCEXEC);} static inteqdirdev(Dir *a, Dir *b){	return a != nil && b != nil &&		a->dev == b->dev && a->type == b->type &&		a->qid.path == b->qid.path;} /* * Print *  sysname: time: mesg * on /sys/log/logname. * If cons or log file can't be opened, print on the system console, too. */voidsyslog(int cons, char *logname, char *fmt, ...){	char buf[1024];	char *ctim, *p;	va_list arg;	int n;	Dir *d;	char err[ERRMAX]; 	err[0] = '\0';	errstr(err, sizeof err);	lock(&sl); 	/*	 *  paranoia makes us stat to make sure a fork+close	 *  hasn't broken our fd's	 */	d = dirfstat(sl.fd);	if(sl.fd < 0 || sl.name == nil || strcmp(sl.name, logname) != 0 ||	   !eqdirdev(d, sl.d)){		free(sl.name);		sl.name = strdup(logname);		if(sl.name == nil)			cons = 1;		else{			free(sl.d);			sl.d = nil;			_syslogopen();			if(sl.fd < 0)				cons = 1;			else				sl.d = dirfstat(sl.fd);		}	}	free(d);	if(cons){		d = dirfstat(sl.consfd);		if(sl.consfd < 0 || !eqdirdev(d, sl.consd)){			free(sl.consd);			sl.consd = nil;			sl.consfd = open("#c/cons", OWRITE|OCEXEC);			if(sl.consfd >= 0)				sl.consd = dirfstat(sl.consfd);		}		free(d);	} 	if(fmt == nil){		unlock(&sl);		return;	} 	ctim = ctime(time(0));	p = buf + snprint(buf, sizeof(buf)-1, "%s ", sysname());	strncpy(p, ctim+4, 15);	p += 15;	*p++ = ' ';	errstr(err, sizeof err);	va_start(arg, fmt);	p = vseprint(p, buf+sizeof(buf)-1, fmt, arg);	va_end(arg);	*p++ = '\n';	n = p - buf; 	if(sl.fd >= 0){		seek(sl.fd, 0, 2);		write(sl.fd, buf, n);	} 	if(cons && sl.consfd >=0)		write(sl.consfd, buf, n); 	unlock(&sl);}