Add small tweaks to the code to fix compilation when ISC assertions are disabled

While implementing the new unit testing framework cmocka, it was found that the
BIND 9 code doesn't compile when assertions are disabled or replaced with any
function (such as mock_assert() from cmocka unit testing framework) that's not
directly recognized as assertion by the compiler.

This made the compiler to complain about blocks of code that was recognized as
unreachable before, but now it isn't.

The changes in this commit include:

* assigns default values to couple of local variables,
* moves some return statements around INSIST assertions,
* adds __builtin_unreachable(); annotations after some INSIST assertions,
* fixes one broken assertion (= instead of ==)

bin/dig/dighost.c

@@ -2291,7 +2291,7 @@ setup_lookup(dig_lookup_t *lookup) {
 
 		if (lookup->ecs_addr != NULL) {
 			uint8_t addr[16];
-			uint16_t family;
+			uint16_t family = 0;
 			uint32_t plen;
 			struct sockaddr *sa;
 			struct sockaddr_in *sin;

bin/named/server.c

@@ -2718,7 +2718,7 @@ catz_create_chg_task(dns_catz_entry_t *entry, dns_catz_zone_t *origin,
 	catz_chgzone_event_t *event;
 	isc_task_t *task;
 	isc_result_t result;
-	isc_taskaction_t action;
+	isc_taskaction_t action = NULL;
 
 	switch (type) {
 	case DNS_EVENT_CATZADDZONE:
@@ -4356,7 +4356,7 @@ configure_view(dns_view_t *view, dns_viewlist_t *viewlist,
 		obj2 = cfg_tuple_get(obj, "response");
 		if (!cfg_obj_isvoid(obj2)) {
 			const char *resp = cfg_obj_asstring(obj2);
-			isc_result_t r;
+			isc_result_t r = DNS_R_SERVFAIL;
 
 			if (strcasecmp(resp, "drop") == 0)
 				r = DNS_R_DROP;
@@ -5036,7 +5036,7 @@ configure_view(dns_view_t *view, dns_viewlist_t *viewlist,
 	obj2 = cfg_tuple_get(obj, "response");
 	if (!cfg_obj_isvoid(obj2)) {
 		const char *resp = cfg_obj_asstring(obj2);
-		isc_result_t r;
+		isc_result_t r = DNS_R_SERVFAIL;
 
 		if (strcasecmp(resp, "drop") == 0)
 			r = DNS_R_DROP;
@@ -5281,7 +5281,7 @@ configure_view(dns_view_t *view, dns_viewlist_t *viewlist,
 		const char *empty_dbtype[4] =
 				    { "_builtin", "empty", NULL, NULL };
 		int empty_dbtypec = 4;
-		dns_zonestat_level_t statlevel;
+		dns_zonestat_level_t statlevel = dns_zonestat_none;
 
 		name = dns_fixedname_initname(&fixed);
 
@@ -9920,7 +9920,7 @@ static void
 named_server_reload(isc_task_t *task, isc_event_t *event) {
 	named_server_t *server = (named_server_t *)event->ev_arg;
 
-	INSIST(task = server->task);
+	INSIST(task == server->task);
 	UNUSED(task);
 
 	isc_log_write(named_g_lctx, NAMED_LOGCATEGORY_GENERAL,
@@ -12586,7 +12586,7 @@ newzone_parse(named_server_t *server, char *command, dns_view_t **viewp,
 	const char *viewname = NULL;
 	dns_rdataclass_t rdclass;
 	dns_view_t *view = NULL;
-	const char *bn;
+	const char *bn = NULL;
 
 	REQUIRE(viewp != NULL && *viewp == NULL);
 	REQUIRE(zoneobjp != NULL && *zoneobjp == NULL);

bin/named/zoneconf.c

@@ -903,7 +903,7 @@ named_zone_configure(const cfg_obj_t *config, const cfg_obj_t *vconfig,
 	const dns_master_style_t *masterstyle = &dns_master_style_default;
 	isc_stats_t *zoneqrystats;
 	dns_stats_t *rcvquerystats;
-	dns_zonestat_level_t statlevel;
+	dns_zonestat_level_t statlevel = dns_zonestat_none;
 	int seconds;
 	dns_zone_t *mayberaw = (raw != NULL) ? raw : zone;
 	isc_dscp_t dscp;

bin/tests/system/rpz/dnsrps.c

@@ -82,10 +82,11 @@ main(int argc, char **argv) {
 			}
 #ifdef USE_DNSRPS
 			printf("%s\n", librpz->dnsrpzd_path);
-			return (0);
 #else
 			INSIST(0);
+			ISC_UNREACHABLE();
 #endif
+			return (0);
 
 		case 'n':
 			if (!link_dnsrps(&emsg)) {
@@ -132,10 +133,11 @@ main(int argc, char **argv) {
 			librpz->rsp_detach(&rsp);
 			librpz->client_detach(&client);
 			printf("%u\n", serial);
-			return (0);
 #else
 			INSIST(0);
+			ISC_UNREACHABLE();
 #endif
+			return (0);
 
 		case 'w':
 			seconds = strtod(optarg, &p);

config.h.in

@@ -60,6 +60,9 @@
 /* Define to 1 if the compiler supports __builtin_expect. */
 #undef HAVE_BUILTIN_EXPECT
 
+/* define if the compiler supports __builtin_unreachable(). */
+#undef HAVE_BUILTIN_UNREACHABLE
+
 /* Define to 1 if you have the `catgets' function. */
 #undef HAVE_CATGETS
 

configure

@@ -18161,6 +18161,38 @@ fi
 done
 
 
+#
+# Check for __builtin_unreachable
+#
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking compiler support for __builtin_unreachable()" >&5
+$as_echo_n "checking compiler support for __builtin_unreachable()... " >&6; }
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+__builtin_unreachable();
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+
+$as_echo "#define HAVE_BUILTIN_UNREACHABLE 1" >>confdefs.h
+
+
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+
 #
 # Check for __builtin_expect
 #

configure.ac

@@ -2017,6 +2017,21 @@ LIBS="$LIBS $ISC_ATOMIC_LIBS"
 
 AC_CHECK_HEADERS([uchar.h])
 
+#
+# Check for __builtin_unreachable
+#
+AC_MSG_CHECKING([compiler support for __builtin_unreachable()])
+AC_LINK_IFELSE(
+  [AC_LANG_PROGRAM(
+     [[]],
+     [[__builtin_unreachable();]]
+   )],
+  [AC_MSG_RESULT([yes])
+   AC_DEFINE([HAVE_BUILTIN_UNREACHABLE], [1], [define if the compiler supports __builtin_unreachable().])
+  ],
+  [AC_MSG_RESULT([no])
+  ])
+
 #
 # Check for __builtin_expect
 #

lib/dns/dnstap.c

@@ -700,6 +700,7 @@ dnstap_type(dns_dtmsgtype_t msgtype) {
 		return (DNSTAP__MESSAGE__TYPE__UPDATE_RESPONSE);
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 }
 

lib/dns/iptable.c

@@ -67,7 +67,7 @@ dns_iptable_addprefix(dns_iptable_t *tab, const isc_netaddr_t *addr,
 	int i;
 
 	INSIST(DNS_IPTABLE_VALID(tab));
-	INSIST(tab->radix);
+	INSIST(tab->radix != NULL);
 
 	NETADDR_TO_PREFIX_T(addr, pfx, bitlen);
 

lib/dns/master.c

@@ -549,8 +549,6 @@ loadctx_create(dns_masterformat_t format, isc_mem_t *mctx,
 
 	lctx->format = format;
 	switch (format) {
-	default:
-		INSIST(0);
 	case dns_masterformat_text:
 		lctx->openfile = openfile_text;
 		lctx->load = load_text;
@@ -563,6 +561,9 @@ loadctx_create(dns_masterformat_t format, isc_mem_t *mctx,
 		lctx->openfile = openfile_map;
 		lctx->load = load_map;
 		break;
+	default:
+		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	if (lex != NULL) {

lib/dns/rpz.c

@@ -567,8 +567,8 @@ adj_trigger_cnt(dns_rpz_zones_t *rpzs, dns_rpz_num_t rpz_num,
 		const dns_rpz_cidr_key_t *tgt_ip, dns_rpz_prefix_t tgt_prefix,
 		bool inc)
 {
-	dns_rpz_trigger_counter_t *cnt;
-	dns_rpz_zbits_t *have;
+	dns_rpz_trigger_counter_t *cnt = 0;
+	dns_rpz_zbits_t *have = 0;
 
 	switch (rpz_type) {
 	case DNS_RPZ_TYPE_CLIENT_IP:
@@ -611,6 +611,7 @@ adj_trigger_cnt(dns_rpz_zones_t *rpzs, dns_rpz_num_t rpz_num,
 		break;
 	default:
 		INSIST(0);
+		ISC_UNREACHABLE();
 	}
 
 	if (inc) {
@@ -2477,7 +2478,7 @@ dns_rpz_find_ip(dns_rpz_zones_t *rpzs, dns_rpz_type_t rpz_type,
 	dns_rpz_addr_zbits_t tgt_set;
 	dns_rpz_cidr_node_t *found;
 	isc_result_t result;
-	dns_rpz_num_t rpz_num;
+	dns_rpz_num_t rpz_num = 0;
 	dns_rpz_have_t have;
 	int i;
 

lib/isc/include/isc/util.h

@@ -203,6 +203,12 @@
  */
 #include <isc/likely.h>
 
+#ifdef HAVE_BUILTIN_UNREACHABLE
+#define ISC_UNREACHABLE() __builtin_unreachable();
+#else
+#define ISC_UNREACHABLE()
+#endif
+
 #ifdef UNIT_TESTING
 extern void mock_assert(const int result, const char* const expression,
 			const char * const file, const int line);

lib/isc/pk11.c

@@ -667,6 +667,7 @@ pk11_numbits(CK_BYTE_PTR data, unsigned int bytecnt) {
 		break;
 	}
 	INSIST(0);
+	ISC_UNREACHABLE();
 }
 
 CK_ATTRIBUTE *

lib/isc/random.c

@@ -114,7 +114,7 @@ isc_random_buf(void *buf, size_t buflen) {
 	int i;
 	uint32_t r;
 
-	REQUIRE(buf);
+	REQUIRE(buf != NULL);
 	REQUIRE(buflen > 0);
 
 	RUNTIME_CHECK(isc_once_do(&isc_random_once,

lib/ns/client.c

@@ -1686,7 +1686,7 @@ ns_client_addopt(ns_client_t *client, dns_message_t *message,
 		isc_buffer_t buf;
 		uint8_t addr[16];
 		uint32_t plen, addrl;
-		uint16_t family;
+		uint16_t family = 0;
 
 		/* Add CLIENT-SUBNET option. */
 

lib/ns/query.c

@@ -2587,7 +2587,7 @@ rpz_get_zbits(ns_client_t *client,
 	      dns_rdatatype_t ip_type, dns_rpz_type_t rpz_type)
 {
 	dns_rpz_st_t *st;
-	dns_rpz_zbits_t zbits;
+	dns_rpz_zbits_t zbits = 0;
 
 	REQUIRE(client != NULL);
 	REQUIRE(client->query.rpz_st != NULL);