fix: handle missing child classes when querying native classes (#1718)

Author: edusperoni

test-app/runtime/src/main/cpp/JEnv.cpp

@@ -723,16 +723,31 @@ jclass JEnv::FindClass(const string &className) {
     jclass global_class = CheckForClassInCache(className);
 
     if (global_class == nullptr) {
+        auto classIsMissing = CheckForClassMissingCache(className);
+        // class is missing. Set the same JNI error we had when we tried to find it the first time
+        if (classIsMissing != nullptr) {
+            m_env->Throw(classIsMissing);
+            return nullptr;
+        }
         jclass tmp = m_env->FindClass(className.c_str());
 
         if (m_env->ExceptionCheck() == JNI_TRUE) {
             m_env->ExceptionClear();
-            string cannonicalClassName = Util::ConvertFromJniToCanonicalName(className);
-            jstring s = m_env->NewStringUTF(cannonicalClassName.c_str());
-            tmp = static_cast<jclass>(m_env->CallStaticObjectMethod(RUNTIME_CLASS,
-                                                                    GET_CACHED_CLASS_METHOD_ID, s));
-
-            m_env->DeleteLocalRef(s);
+             string cannonicalClassName = Util::ConvertFromJniToCanonicalName(className);
+             jstring s = m_env->NewStringUTF(cannonicalClassName.c_str());
+             tmp = static_cast<jclass>(m_env->CallStaticObjectMethod(RUNTIME_CLASS,
+                                                                     GET_CACHED_CLASS_METHOD_ID, s));
+
+             m_env->DeleteLocalRef(s);
+            // we failed our static class check
+            // if we continue, we will crash (C++ level)
+            // so just return null and let the runtime deal with the NativeScriptException
+            if (m_env->ExceptionCheck() == JNI_TRUE) {
+                auto tmpException = m_env->ExceptionOccurred();
+                m_env->ExceptionClear();
+                m_env->Throw(InsertClassIntoMissingCache(className, tmpException));
+                return nullptr;
+            }
         }
 
         global_class = InsertClassIntoCache(className, tmp);
@@ -760,6 +775,25 @@ jclass JEnv::InsertClassIntoCache(const string &className, jclass &tmp) {
     return global_class;
 }
 
+jthrowable JEnv::CheckForClassMissingCache(const string &className) {
+    jthrowable throwable = nullptr;
+    auto itFound = s_missingClasses.find(className);
+
+    if (itFound != s_missingClasses.end()) {
+        throwable = itFound->second;
+    }
+
+    return throwable;
+}
+
+jthrowable JEnv::InsertClassIntoMissingCache(const string &className,const jthrowable &tmp) {
+    auto throwable = reinterpret_cast<jthrowable>(m_env->NewGlobalRef(tmp));
+    s_missingClasses.insert(make_pair(className, throwable));
+    m_env->DeleteLocalRef(tmp);
+
+    return throwable;
+}
+
 jobject JEnv::NewDirectByteBuffer(void *address, jlong capacity) {
     jobject jo = m_env->NewDirectByteBuffer(address, capacity);
     CheckForJavaException();
@@ -822,6 +856,7 @@ void JEnv::CheckForJavaException() {
 
 JavaVM *JEnv::s_jvm = nullptr;
 map<string, jclass> JEnv::s_classCache;
+map<string, jthrowable> JEnv::s_missingClasses;
 jclass JEnv::RUNTIME_CLASS = nullptr;
 jmethodID JEnv::GET_CACHED_CLASS_METHOD_ID = nullptr;
 

test-app/runtime/src/main/cpp/JEnv.h

@@ -191,6 +191,16 @@ class JEnv {
          */
         jclass InsertClassIntoCache(const std::string& className, jclass& tmp);
 
+
+        /*
+         * The "CheckForClassMissing" will check if a class has been checked and it was missing, if it is, it will return the original throwable
+         * this is useful for rethrowing exceptions if they were caught in the previous attempt of loading it.
+         * if it is not: it will return "nullptr".
+         */
+        jthrowable CheckForClassMissingCache(const std::string& className);
+
+        jthrowable InsertClassIntoMissingCache(const std::string& className, const jthrowable& tmp);
+
         jobject NewDirectByteBuffer(void* address, jlong capacity);
         void* GetDirectBufferAddress(jobject buf);
         jlong GetDirectBufferCapacity(jobject buf);
@@ -333,6 +343,7 @@ class JEnv {
         static jmethodID GET_CACHED_CLASS_METHOD_ID;
 
         static std::map<std::string, jclass> s_classCache;
+        static std::map<std::string, jthrowable> s_missingClasses;
 };
 }
 

test-app/runtime/src/main/cpp/MetadataNode.cpp

@@ -884,6 +884,10 @@ void MetadataNode::SetInnerTypes(Isolate* isolate, Local<Function>& ctorFunction
 
             // The call to GetConstructorFunctionTemplate bootstraps the ctor function for the childNode
             auto innerTypeCtorFuncTemplate = childNode->GetConstructorFunctionTemplate(isolate, curChild);
+            if(innerTypeCtorFuncTemplate.IsEmpty()) {
+                // this class does not exist, so just ignore it
+                continue;
+            }
             auto innerTypeCtorFunc = Local<Function>::New(isolate, *GetOrCreateInternal(curChild)->GetPersistentConstructorFunction(isolate));
             auto innerTypeName = ArgConverter::ConvertToV8String(isolate, curChild->name);
             ctorFunction->Set(context, innerTypeName, innerTypeCtorFunc);
@@ -917,6 +921,25 @@ Local<FunctionTemplate> MetadataNode::GetConstructorFunctionTemplate(Isolate* is
     //
 
     auto node = GetOrCreateInternal(treeNode);
+
+
+    JEnv env;
+    // if we already have an exception (which will be rethrown later)
+    // then we don't want to ignore the next exception
+    bool ignoreFindClassException = env.ExceptionCheck() == JNI_FALSE;
+    auto currentClass = env.FindClass(node->m_name);
+    if (ignoreFindClassException && env.ExceptionCheck()) {
+        env.ExceptionClear();
+        // JNI found an exception looking up this class
+        // but we don't care, because this means this class doesn't exist
+        // like when you try to get a class that only exists in a higher API level
+        ctorFuncTemplate.Clear();
+        auto pft = new Persistent<FunctionTemplate>(isolate, ctorFuncTemplate);
+        CtorCacheData ctorCacheItem(pft, instanceMethodsCallbackData);
+        cache->CtorFuncCache.insert(make_pair(treeNode, ctorCacheItem));
+        return ctorFuncTemplate;
+    }
+
     auto ctorCallbackData = External::New(isolate, node);
     auto isInterface = s_metadataReader.IsNodeTypeInterface(treeNode->type);
     auto funcCallback = isInterface ? InterfaceConstructorCallback : ClassConstructorCallback;
@@ -926,8 +949,6 @@ Local<FunctionTemplate> MetadataNode::GetConstructorFunctionTemplate(Isolate* is
     Local<Function> baseCtorFunc;
     std::vector<MethodCallbackData*> baseInstanceMethodsCallbackData;
     auto tmpTreeNode = treeNode;
-    JEnv env;
-    auto currentClass = env.FindClass(node->m_name);
     std::vector<MetadataTreeNode*> skippedBaseTypes;
     while (true) {
         auto baseTreeNode = s_metadataReader.GetBaseClassNode(tmpTreeNode);