Issue 1848 - Clean up local reference handling

jni/JniFilterEngine.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2015 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 16 matching lines @@
   {
     JniAddObjectToList(env, list, NewJniSubscription(env, *it));
   }
 
   return list;
 }
 
 static AdblockPlus::FilterEngine::ContentType ConvertContentType(JNIEnv *env,
     jobject jContentType)
 {
-  jclass contentTypeClass = env->GetObjectClass(jContentType);
-  jmethodID nameMethod = env->GetMethodID(contentTypeClass, "name",
+  JniLocalReference<jclass> contentTypeClass(env, env->GetObjectClass(jContentType));
+  jmethodID nameMethod = env->GetMethodID(*contentTypeClass, "name",
                                           "()Ljava/lang/String;");
-  jstring jValue = (jstring) env->CallObjectMethod(jContentType, nameMethod);
-  const std::string value = JniJavaToStdString(env, jValue);
+  JniLocalReference<jstring> jValue(env, (jstring) env->CallObjectMethod(jContentType, nameMethod));
+  const std::string value = JniJavaToStdString(env, *jValue);
   return AdblockPlus::FilterEngine::StringToContentType(value);
 }
 
 static jlong JNICALL JniCtor(JNIEnv* env, jclass clazz, jlong enginePtr)
 {
   try
   {
     AdblockPlus::JsEnginePtr& jsEngine = *JniLongToTypePtr<AdblockPlus::JsEnginePtr>(enginePtr);
     return JniPtrToLong(new AdblockPlus::FilterEngine(jsEngine));
   }
@@ skipping 35 matching lines @@
   AdblockPlus::FilterEngine* engine = JniLongToTypePtr<AdblockPlus::FilterEngine>(ptr);
 
   try
   {
     std::vector<AdblockPlus::FilterPtr> filters = engine->GetListedFilters();
 
     jobject list = NewJniArrayList(env);
 
     for (std::vector<AdblockPlus::FilterPtr>::iterator it = filters.begin(), end = filters.end(); it != end; it++)
     {
-      JniAddObjectToList(env, list, NewJniFilter(env, *it));
+      JniAddObjectToList(env, list, *JniLocalReference<jobject>(env, NewJniFilter(env, *it)));
     }
 
     return list;
   }
   CATCH_THROW_AND_RETURN(env, 0);
 }
 
 static jobject JNICALL JniGetSubscription(JNIEnv* env, jclass clazz, jlong ptr, jstring jUrl)
 {
   AdblockPlus::FilterEngine* engine = JniLongToTypePtr<AdblockPlus::FilterEngine>(ptr);
@@ skipping 119 matching lines @@
   std::string domain = JniJavaToStdString(env, jDomain);
 
   try
   {
     std::vector<std::string> selectors = engine->GetElementHidingSelectors(domain);
 
     jobject list = NewJniArrayList(env);
 
     for (std::vector<std::string>::iterator it = selectors.begin(), end = selectors.end(); it != end; it++)
     {
-      JniAddObjectToList(env, list, env->NewStringUTF(it->c_str()));
+      JniAddObjectToList(env, list, *JniLocalReference<jstring>(env, env->NewStringUTF(it->c_str())));
     }
 
     return list;
   }
   CATCH_THROW_AND_RETURN(env, 0)
 }
 
 static jobject JNICALL JniMatches(JNIEnv* env, jclass clazz, jlong ptr, jstring jUrl, jobject jContentType, jstring jDocumentUrl)
 {
   AdblockPlus::FilterEngine* engine = JniLongToTypePtr<AdblockPlus::FilterEngine>(ptr);
@@ skipping 19 matching lines @@
   std::string url = JniJavaToStdString(env, jUrl);
   AdblockPlus::FilterEngine::ContentType contentType =
       ConvertContentType(env, jContentType);
 
   std::vector<std::string> documentUrls;
 
   jsize len = env->GetArrayLength(jDocumentUrls);
 
   for (jsize i = 0; i < len; i++)
   {
-    documentUrls.push_back(JniJavaToStdString(env, static_cast<jstring>(env->GetObjectArrayElement(jDocumentUrls, i))));
+    documentUrls.push_back(JniJavaToStdString(env,
+        *JniLocalReference<jstring>(env, static_cast<jstring>(env->GetObjectArrayElement(jDocumentUrls, i)))));
   }
 
   try
   {
     AdblockPlus::FilterPtr filter = engine->Matches(url, contentType, documentUrls);
 
     return NewJniFilter(env, filter);
   }
   CATCH_THROW_AND_RETURN(env, 0)
 }
@@ skipping 46 matching lines @@
   { (char*)"matches", (char*)"(JLjava/lang/String;" TYP("FilterEngine$ContentType") "[Ljava/lang/String;)" TYP("Filter"), (void*)JniMatchesMany },
   { (char*)"getPref", (char*)"(JLjava/lang/String;)" TYP("JsValue"), (void*)JniGetPref },
   { (char*)"setPref", (char*)"(JLjava/lang/String;J)V", (void*)JniSetPref },
   { (char*)"dtor", (char*)"(J)V", (void*)JniDtor }
 };
 
 extern "C" JNIEXPORT void JNICALL Java_org_adblockplus_libadblockplus_FilterEngine_registerNatives(JNIEnv *env, jclass clazz)
 {
   env->RegisterNatives(clazz, methods, sizeof(methods) / sizeof(methods[0]));
 }