1 #include <u.h>
2 #include <libc.h>
3 
4 static struct
5 {
6 	int	fd;
7 	int	consfd;
8 	char	*name;
9 	Dir	*d;
10 	Dir	*consd;
11 	Lock	lk;
12 } sl =
13 {
14 	-1, -1,
15 };
16 
17 static void
18 _syslogopen(void)
19 {
20 	char buf[1024], *p;
21 
22 	if(sl.fd >= 0)
23 		close(sl.fd);
24 	snprint(buf, sizeof(buf), "#9/log/%s", sl.name);
25 	p = unsharp(buf);
26 	sl.fd = open(p, OWRITE|OCEXEC|OAPPEND);
27 	free(p);
28 }
29 
30 /*
31  * Print
32  *  sysname: time: mesg
33  * on /sys/log/logname.
34  * If cons or log file can't be opened, print on the system console, too.
35  */
36 void
37 syslog(int cons, char *logname, char *fmt, ...)
38 {
39 	char buf[1024];
40 	char *ctim, *p;
41 	va_list arg;
42 	int n;
43 	Dir *d;
44 	char err[ERRMAX];
45 
46 	err[0] = '\0';
47 	errstr(err, sizeof err);
48 	lock(&sl.lk);
49 
50 	/*
51 	 *  paranoia makes us stat to make sure a fork+close
52 	 *  hasn't broken our fd's
53 	 */
54 	d = dirfstat(sl.fd);
55 	if(sl.fd < 0
56 	   || sl.name == nil
57 	   || strcmp(sl.name, logname)!=0
58 	   || sl.d == nil
59 	   || d == nil
60 	   || d->dev != sl.d->dev
61 	   || d->type != sl.d->type
62 	   || d->qid.path != sl.d->qid.path){
63 		free(sl.name);
64 		sl.name = strdup(logname);
65 		if(sl.name == nil)
66 			cons = 1;
67 		else{
68 			_syslogopen();
69 			if(sl.fd < 0)
70 				cons = 1;
71 			free(sl.d);
72 			sl.d = d;
73 			d = nil;	/* don't free it */
74 		}
75 	}
76 	free(d);
77 	if(cons){
78 		d = dirfstat(sl.consfd);
79 		if(sl.consfd < 0
80 		   || d == nil
81 		   || sl.consd == nil
82 		   || d->dev != sl.consd->dev
83 		   || d->type != sl.consd->type
84 		   || d->qid.path != sl.consd->qid.path){
85 			sl.consfd = open("/dev/tty", OWRITE|OCEXEC);
86 			free(sl.consd);
87 			sl.consd = d;
88 			d = nil;	/* don't free it */
89 		}
90 		free(d);
91 	}
92 
93 	if(fmt == nil){
94 		unlock(&sl.lk);
95 		return;
96 	}
97 
98 	ctim = ctime(time(0));
99 	werrstr(err);
100 	p = buf + snprint(buf, sizeof(buf)-1, "%s ", sysname());
101 	strncpy(p, ctim+4, 15);
102 	p += 15;
103 	*p++ = ' ';
104 	va_start(arg, fmt);
105 	p = vseprint(p, buf+sizeof(buf)-1, fmt, arg);
106 	va_end(arg);
107 	*p++ = '\n';
108 	n = p - buf;
109 
110 	if(sl.fd >= 0){
111 		seek(sl.fd, 0, 2);
112 		write(sl.fd, buf, n);
113 	}
114 
115 	if(cons && sl.consfd >=0)
116 		write(sl.consfd, buf, n);
117 
118 	unlock(&sl.lk);
119 }