#include <u.h>#include <libc.h> /* * Print *  sysname: time: user: [prog: ]msg[: errmsg] * on /sys/log/logname, creating it (append only) if it doesn't exist. * Print the prog if argv0 is not 0. * 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, *ebuf, *t;	int f, n;	static char user[NAMELEN];	static char name[NAMELEN];	static char sysname[NAMELEN];	static int logfd = -1;	static int consfd = -1; 	if(logfd<0 || strcmp(name, logname)!=0){		strncpy(name, logname, NAMELEN-1);		if(logfd >= 0)			close(logfd);		doprint(buf, buf+sizeof(buf), "/sys/log/%s", &logname);		logfd = open(buf, OWRITE);		if(logfd < 0)			cons = 1;	}	if(cons && consfd<0)		consfd = open("#c/cons", OWRITE);	if(sysname[0] == 0){		strcpy(sysname, "gnot");		f = open("/env/sysname", OREAD);		if(f >= 0){			read(f, sysname, NAMELEN-1);			close(f);		}	}	if(user[0] == 0){		f = open("/dev/user", OREAD);		if(f >= 0){			if(read(f, user, NAMELEN-1) <= 0)				strcpy(user, "ditzel");			close(f);		}	}	ctim = ctime(time(0));	ebuf = buf+sizeof(buf)-1; /* leave room for newline */	t = sysname;	p = doprint(buf, ebuf, "%s: ", &t);	strncpy(p, ctim+4, 15);	p += 15;	t = user;	if(user[0])		p = doprint(p, ebuf, ": %s: ", &t);	if(argv0)		p = doprint(p, ebuf, "%s: ", &argv0);	p = doprint(p, ebuf, fmt, (&fmt+1));	*p++ = '\n';	n = p - buf;	if(logfd >= 0){		seek(logfd, 0, 2);	/* in case it's not append-only */		write(logfd, buf, n);	}	if(cons && consfd >=0)		write(consfd, buf, n);}