#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);} /* * 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	   || sl.d == nil	   || d == nil	   || d->dev != sl.d->dev	   || d->type != sl.d->type	   || d->qid.path != sl.d->qid.path){		free(sl.name);		sl.name = strdup(logname);		if(sl.name == nil)			cons = 1;		else{			_syslogopen();			if(sl.fd < 0)				cons = 1;			free(sl.d);			sl.d = d;			d = nil;	/* don't free it */		}	}	free(d);	if(cons){		d = dirfstat(sl.consfd);		if(sl.consfd < 0		   || d == nil		   || sl.consd == nil		   || d->dev != sl.consd->dev		   || d->type != sl.consd->type		   || d->qid.path != sl.consd->qid.path){			sl.consfd = open("#c/cons", OWRITE|OCEXEC);			free(sl.consd);			sl.consd = d;			d = nil;	/* don't free it */		}		free(d);	} 	if(fmt == nil){		unlock(&sl);		return;	} 	ctim = ctime(time(0));	werrstr(err);	p = buf + snprint(buf, sizeof(buf)-1, "%s ", sysname());	strncpy(p, ctim+4, 15);	p += 15;	*p++ = ' ';	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);}