simplify syslog, add vsyslog interface (nonstandard)

with datagram sockets, depending on fprintf not to flush the output
early was very fragile; the new version simply uses a small fixed-size
buffer. it could be updated to dynamic-allocate large buffers if
needed, but i can't envision any admin being happy about finding
64kb-long lines in their syslog...

src/misc/syslog.c

@@ -14,7 +14,7 @@ static const char *log_ident;
 static int log_opt;
 static int log_facility = LOG_USER;
 static int log_mask = 0xff;
-static FILE *log_f;
+static int log_fd = -1;
 
 int setlogmask(int maskpri)
 {
@@ -34,26 +34,21 @@ static const struct {
 void closelog(void)
 {
 	LOCK(&lock);
-	if (log_f) fclose(log_f);
-	log_f = NULL;
+	close(log_fd);
+	log_fd = -1;
 	UNLOCK(&lock);
 }
 
 static void __openlog(const char *ident, int opt, int facility)
 {
-	int fd;
-
 	log_ident = ident;
 	log_opt = opt;
 	log_facility = facility;
 
-	if (!(opt & LOG_NDELAY) || log_f) return;
+	if (!(opt & LOG_NDELAY) || log_fd>=0) return;
 
-	fd = socket(AF_UNIX, SOCK_DGRAM, 0);
-	fcntl(fd, F_SETFD, FD_CLOEXEC);
-	if (connect(fd, (void *)&log_addr, sizeof(short) + sizeof "/dev/log") < 0)
-		close(fd);
-	else log_f = fdopen(fd, "wb");
+	log_fd = socket(AF_UNIX, SOCK_DGRAM, 0);
+	fcntl(log_fd, F_SETFD, FD_CLOEXEC);
 }
 
 void openlog(const char *ident, int opt, int facility)
@@ -63,42 +58,52 @@ void openlog(const char *ident, int opt, int facility)
 	UNLOCK(&lock);
 }
 
-void syslog(int priority, const char *message, ...)
+void __vsyslog(int priority, const char *message, va_list ap)
 {
-	va_list ap;
 	char timebuf[16];
 	time_t now;
 	struct tm tm;
-	//const char *fmt, *ident, *sep;
-	//int i;
+	char buf[256];
+	int pid;
+	int l, l2;
 
 	if (!(log_mask & LOG_MASK(priority&7)) || (priority&~0x3ff)) return;
 
 	LOCK(&lock);
 
-	if (!log_f) __openlog(log_ident, log_opt | LOG_NDELAY, log_facility);
-	if (!log_f) {
-		UNLOCK(&lock);
-		return;
+	if (log_fd < 0) {
+		__openlog(log_ident, log_opt | LOG_NDELAY, log_facility);
+		if (log_fd < 0) {
+			UNLOCK(&lock);
+			return;
+		}
 	}
 
 	now = time(NULL);
 	gmtime_r(&now, &tm);
 	strftime(timebuf, sizeof timebuf, "%b %e %T", &tm);
 
-	fprintf(log_f, "<%d>%s ", priority, timebuf);
-	if (log_ident) fprintf(log_f, "%s", log_ident);
-	if (log_opt & LOG_PID) fprintf(log_f, "[%d]", getpid());
-	if (log_ident) fprintf(log_f, ": ");
+	pid = (log_opt & LOG_PID) ? getpid() : 0;
+	l = snprintf(buf, sizeof buf, "<%d>%s %s%s%.0d%s: ",
+		priority, timebuf,
+		log_ident ? log_ident : "",
+		"["+!pid, pid, "]"+!pid);
+	l2 = vsnprintf(buf+l, sizeof buf - l, message, ap);
+	if (l2 >= 0) {
+		l += l2;
+		if (buf[l-1] != '\n') buf[l++] = '\n';
+		sendto(log_fd, buf, l, 0, (void *)&log_addr, 11);
+	}
+
+	UNLOCK(&lock);
+}
 
+void syslog(int priority, const char *message, ...)
+{
+	va_list ap;
 	va_start(ap, message);
-	vfprintf(log_f, message, ap);
+	__vsyslog(priority, message, ap);
 	va_end(ap);
-	fputc(0, log_f);
-	fflush(log_f);
-
-	// Note: LOG_CONS is not supported because it is annoying!!
-	// syslogd will send messages to console if it deems them appropriate!
-
-	UNLOCK(&lock);
 }
+
+weak_alias(__vsyslog, vsyslog);