Add dns_zone_logv()

Add a new libdns function, dns_zone_logv(), which takes a single va_list
argument rather than a variable number of arguments and can be used as a
base for implementing more specific zone logging functions.

(cherry picked from commit bb2dfb3f49)

lib/dns/include/dns/zone.h

@@ -2013,6 +2013,15 @@ dns_zone_setdialup(dns_zone_t *zone, dns_dialuptype_t dialup);
  *\li	'dialup' to be a valid dialup type.
  */
 
+void
+dns_zone_logv(dns_zone_t *zone, isc_logcategory_t *category, int level,
+	      const char *prefix, const char *msg, va_list ap);
+/*%<
+ * Log the message 'msg...' at 'level' using log category 'category', including
+ * text that identifies the message as applying to 'zone'.  If the (optional)
+ * 'prefix' is not NULL, it will be placed at the start of the entire log line.
+ */
+
 void
 dns_zone_log(dns_zone_t *zone, int level, const char *msg, ...)
 	ISC_FORMAT_PRINTF(3, 4);

lib/dns/win32/libdns.def.in

@@ -1272,6 +1272,7 @@ dns_zone_loadandthaw
 dns_zone_loadnew
 dns_zone_log
 dns_zone_logc
+dns_zone_logv
 dns_zone_maintenance
 dns_zone_markdirty
 dns_zone_name

lib/dns/zone.c

@@ -13815,6 +13815,37 @@ dns_zone_nameonly(dns_zone_t *zone, char *buf, size_t length) {
 	zone_name_tostr(zone, buf, length);
 }
 
+void
+dns_zone_logv(dns_zone_t *zone, isc_logcategory_t *category, int level,
+	      const char *prefix, const char *fmt, va_list ap)
+{
+	char message[4096];
+	const char *zstr;
+
+	if (!isc_log_wouldlog(dns_lctx, level)) {
+		return;
+	}
+
+	vsnprintf(message, sizeof(message), fmt, ap);
+
+	switch (zone->type) {
+	case dns_zone_key:
+		zstr = "managed-keys-zone";
+		break;
+	case dns_zone_redirect:
+		zstr = "redirect-zone";
+		break;
+	default:
+		zstr = "zone ";
+	}
+
+	isc_log_write(dns_lctx, category, DNS_LOGMODULE_ZONE, level,
+		      "%s%s%s%s: %s",
+		      (prefix != NULL ? prefix : ""),
+		      (prefix != NULL ? ": " : ""),
+		      zstr, zone->strnamerd, message);
+}
+
 static void
 notify_log(dns_zone_t *zone, int level, const char *fmt, ...) {
 	va_list ap;