save zone configuration as text

as previously mentioned in commit c65b2868ab, a cfg_obj_t
configuration tree structure takes up considerably more space than
the canonical text. since the zone configuration saved in the zone
object using dns_zone_setcfg() is only currently used for "rndc
showzone", it can be saved as text more efficiently than as an
object tree. (and, if a tree were needed, the text could be
re-parsed quickly; zone configuration text is generally small.)

bin/named/server.c

@@ -6040,6 +6040,39 @@ create_view(const cfg_obj_t *vconfig, dns_viewlist_t *viewlist,
 	return ISC_R_SUCCESS;
 }
 
+static void
+emit_text(void *arg, const char *buf, int len) {
+	ns_dzarg_t *dzarg = arg;
+	isc_result_t result;
+
+	REQUIRE(dzarg != NULL && ISC_MAGIC_VALID(dzarg, DZARG_MAGIC));
+	result = putmem(dzarg->text, buf, len);
+	if (result != ISC_R_SUCCESS && dzarg->result == ISC_R_SUCCESS) {
+		dzarg->result = result;
+	}
+}
+
+static isc_result_t
+save_zoneconfig(dns_zone_t *zone, const cfg_obj_t *zconfig) {
+	isc_result_t result;
+	isc_buffer_t *text = NULL;
+	ns_dzarg_t dzarg = {
+		.magic = DZARG_MAGIC,
+		.text = &text,
+	};
+
+	isc_buffer_allocate(isc_g_mctx, &text, 256);
+
+	cfg_printx(zconfig, CFG_PRINTER_ONELINE, emit_text, &dzarg);
+	CHECK(putnull(&text));
+
+	dns_zone_setcfg(zone, isc_buffer_base(text));
+
+cleanup:
+	isc_buffer_free(&text);
+	return result;
+}
+
 /*
  * Configure or reconfigure a zone.
  */
@@ -6249,6 +6282,7 @@ configure_zone(const cfg_obj_t *config, const cfg_obj_t *zconfig,
 		}
 		CHECK(named_zone_configure(config, vconfig, zconfig, aclctx,
 					   kasplist, zone, NULL));
+		CHECK(save_zoneconfig(zone, zconfig));
 		dns_zone_attach(zone, &view->redirect);
 		goto cleanup;
 	}
@@ -6425,6 +6459,7 @@ configure_zone(const cfg_obj_t *config, const cfg_obj_t *zconfig,
 	 */
 	CHECK(named_zone_configure(config, vconfig, zconfig, aclctx, kasplist,
 				   zone, raw));
+	CHECK(save_zoneconfig(zone, zconfig));
 
 	/*
 	 * Add the zone to its view in the new view list.
@@ -9077,18 +9112,6 @@ cleanup_aclctx:
 	return result;
 }
 
-static void
-emit_text(void *arg, const char *buf, int len) {
-	ns_dzarg_t *dzarg = arg;
-	isc_result_t result;
-
-	REQUIRE(dzarg != NULL && ISC_MAGIC_VALID(dzarg, DZARG_MAGIC));
-	result = putmem(dzarg->text, buf, len);
-	if (result != ISC_R_SUCCESS && dzarg->result == ISC_R_SUCCESS) {
-		dzarg->result = result;
-	}
-}
-
 static isc_result_t
 load_configuration(named_server_t *server, bool first_time) {
 	isc_result_t result;
@@ -13842,10 +13865,9 @@ isc_result_t
 named_server_showzone(named_server_t *server, isc_lex_t *lex,
 		      isc_buffer_t **text) {
 	isc_result_t result;
-	const cfg_obj_t *zconfig = NULL;
 	char zonename[DNS_NAME_FORMATSIZE];
 	dns_zone_t *zone = NULL;
-	ns_dzarg_t dzarg;
+	const char *zconfig = NULL;
 
 	REQUIRE(text != NULL);
 
@@ -13864,12 +13886,7 @@ named_server_showzone(named_server_t *server, isc_lex_t *lex,
 	}
 
 	CHECK(putstr(text, "zone "));
-	dzarg.magic = DZARG_MAGIC;
-	dzarg.text = text;
-	dzarg.result = ISC_R_SUCCESS;
-	cfg_printx(zconfig, CFG_PRINTER_ONELINE, emit_text, &dzarg);
-	CHECK(dzarg.result);
-
+	CHECK(putstr(text, zconfig));
 	CHECK(putstr(text, ";"));
 
 	result = ISC_R_SUCCESS;

bin/named/zoneconf.c

@@ -869,12 +869,6 @@ process_notifytype(dns_notifytype_t ntype, dns_zonetype_t ztype,
 	return dns_notifytype_explicit;
 }
 
-static void
-detach_cfg(void *arg) {
-	cfg_obj_t *cfg = (cfg_obj_t *)arg;
-	cfg_obj_detach(&cfg);
-}
-
 isc_result_t
 named_zone_configure(const cfg_obj_t *config, const cfg_obj_t *vconfig,
 		     const cfg_obj_t *zconfig, cfg_aclconfctx_t *aclctx,
@@ -1913,11 +1907,6 @@ named_zone_configure(const cfg_obj_t *config, const cfg_obj_t *vconfig,
 		break;
 	}
 
-	/* Save the configuration for later use */
-	cfg_obj_t *cfg = UNCONST(zconfig);
-	cfg_obj_ref(cfg);
-	dns_zone_setcfg(zone, (void *)cfg, detach_cfg);
-
 	result = ISC_R_SUCCESS;
 
 cleanup:

lib/dns/include/dns/zone.h

@@ -2763,19 +2763,20 @@ dns_zone_unloadplugins(dns_zone_t *zone);
  */
 
 void
-dns_zone_setcfg(dns_zone_t *zone, void *cfg, void (*cfg_detach)(void *));
+dns_zone_setcfg(dns_zone_t *zone, const char *cfg);
 /*%<
- * Set a pointer to the configuration object for 'zone', which can be
+ * Save a copy of the configuration text for 'zone', which can be
  * used later to dump the configuration status.
  *
  * Requires:
  * \li	'zone' to be a valid zone.
  */
-void *
+
+const char *
 dns_zone_getcfg(dns_zone_t *zone);
 /*%<
- * Return a pointer to the configuration object for 'zone', that was
- * previously set using _setcfg().
+ * Return a pointer to the configuration text for 'zone', that was
+ * previously saved using _setcfg().
  *
  * Requires:
  * \li	'zone' to be a valid zone.

lib/dns/zone.c

@@ -528,9 +528,8 @@ struct dns_zone {
 	void *hooktable;
 	void (*hooktable_free)(isc_mem_t *, void **);
 
-	/* Configuration object */
-	void *cfg;
-	void (*cfg_detach)(void *);
+	/* Configuration text */
+	char *cfg;
 };
 
 #define zonediff_init(z, d)                \
@@ -14718,7 +14717,7 @@ zone_shutdown(void *arg) {
 	}
 
 	/* Detach the zone configuration pointer */
-	dns_zone_setcfg(zone, NULL, NULL);
+	dns_zone_setcfg(zone, NULL);
 
 	LOCK_ZONE(zone);
 	INSIST(zone != zone->raw);
@@ -24058,18 +24057,18 @@ dns_zone_unloadplugins(dns_zone_t *zone) {
 }
 
 void
-dns_zone_setcfg(dns_zone_t *zone, void *cfg, void (*cfg_detach)(void *)) {
+dns_zone_setcfg(dns_zone_t *zone, const char *cfg) {
 	REQUIRE(DNS_ZONE_VALID(zone));
 
-	if (zone->cfg != NULL && zone->cfg_detach != NULL) {
-		zone->cfg_detach(zone->cfg);
-		zone->cfg = NULL;
+	if (zone->cfg != NULL) {
+		isc_mem_free(zone->mctx, zone->cfg);
+	}
+	if (cfg != NULL) {
+		zone->cfg = isc_mem_strdup(zone->mctx, cfg);
 	}
-	zone->cfg = cfg;
-	zone->cfg_detach = cfg_detach;
 }
 
-void *
+const char *
 dns_zone_getcfg(dns_zone_t *zone) {
 	REQUIRE(DNS_ZONE_VALID(zone));