Fixed some issues found by tests with enabled UndefinedBehaviorSanitizer

src/nxt_http_js.c

@@ -162,6 +162,7 @@ static njs_int_t
 nxt_http_js_ext_get_args(njs_vm_t *vm, njs_object_prop_t *prop,
     njs_value_t *value, njs_value_t *setval, njs_value_t *retval)
 {
+    u_char              *start;
     njs_int_t           ret;
     njs_value_t         *args;
     njs_opaque_value_t  val;
@@ -175,8 +176,8 @@ nxt_http_js_ext_get_args(njs_vm_t *vm, njs_object_prop_t *prop,
 
     args = njs_value_arg(&val);
 
-    ret = njs_vm_query_string_parse(vm, r->args->start,
-                                    r->args->start + r->args->length, args);
+    start = (r->args->start != NULL) ? r->args->start : (u_char *) "";
+    ret = njs_vm_query_string_parse(vm, start, start + r->args->length, args);
 
     if (ret == NJS_ERROR) {
         return NJS_ERROR;

src/nxt_http_request.c

@@ -946,6 +946,10 @@ nxt_http_arguments_parse(nxt_http_request_t *r)
         return NULL;
     }
 
+    if (nxt_slow_path(r->args->start == NULL)) {
+        goto end;
+    }
+
     hash = NXT_HTTP_FIELD_HASH_INIT;
     name = NULL;
     name_length = 0;
@@ -1026,6 +1030,8 @@ nxt_http_arguments_parse(nxt_http_request_t *r)
         }
     }
 
+end:
+
     r->arguments = args;
 
     return args;

src/nxt_http_route.c

@@ -2134,6 +2134,10 @@ nxt_http_route_pattern(nxt_http_request_t *r, nxt_http_route_pattern_t *pattern,
         return 0;
     }
 
+    if (nxt_slow_path(start == NULL)) {
+        return 1;
+    }
+
     nxt_assert(pattern->u.pattern_slices != NULL);
 
     pattern_slices = pattern->u.pattern_slices;

src/nxt_port_memory.c

@@ -454,6 +454,10 @@ nxt_port_mmap_get(nxt_task_t *task, nxt_port_mmaps_t *mmaps, nxt_chunk_id_t *c,
 
     nxt_thread_mutex_lock(&mmaps->mutex);
 
+    if (nxt_slow_path(mmaps->elts == NULL)) {
+        goto end;
+    }
+
     end_port_mmap = mmaps->elts + mmaps->size;
 
     for (port_mmap = mmaps->elts;
@@ -500,6 +504,8 @@ nxt_port_mmap_get(nxt_task_t *task, nxt_port_mmaps_t *mmaps, nxt_chunk_id_t *c,
 
     /* TODO introduce port_mmap limit and release wait. */
 
+end:
+
     *c = 0;
     mmap_handler = nxt_port_new_port_mmap(task, mmaps, tracking, n);
 

src/nxt_random.c

@@ -148,10 +148,10 @@ nxt_random(nxt_random_t *r)
         nxt_random_stir(r);
     }
 
-    val  = nxt_random_byte(r) << 24;
-    val |= nxt_random_byte(r) << 16;
-    val |= nxt_random_byte(r) << 8;
-    val |= nxt_random_byte(r);
+    val  = (uint32_t) nxt_random_byte(r) << 24;
+    val |= (uint32_t) nxt_random_byte(r) << 16;
+    val |= (uint32_t) nxt_random_byte(r) << 8;
+    val |= (uint32_t) nxt_random_byte(r);
 
     return val;
 }

src/nxt_unit.c

@@ -1483,9 +1483,9 @@ nxt_unit_request_check_response_port(nxt_unit_request_info_t *req,
     pthread_mutex_lock(&lib->mutex);
 
     port = nxt_unit_port_hash_find(&lib->ports, port_id, 0);
-    port_impl = nxt_container_of(port, nxt_unit_port_impl_t, port);
 
     if (nxt_fast_path(port != NULL)) {
+        port_impl = nxt_container_of(port, nxt_unit_port_impl_t, port);
         req->response_port = port;
 
         if (nxt_fast_path(port_impl->ready)) {
@@ -3502,6 +3502,10 @@ nxt_unit_mmap_get(nxt_unit_ctx_t *ctx, nxt_unit_port_t *port,
 
     pthread_mutex_lock(&lib->outgoing.mutex);
 
+    if (nxt_slow_path(lib->outgoing.elts == NULL)) {
+        goto skip;
+    }
+
 retry:
 
     outgoing_size = lib->outgoing.size;
@@ -3598,6 +3602,8 @@ nxt_unit_mmap_get(nxt_unit_ctx_t *ctx, nxt_unit_port_t *port,
         goto retry;
     }
 
+skip:
+
     *c = 0;
     hdr = nxt_unit_new_mmap(ctx, port, *n);