Handle network errors better

jni/AndroidWebRequest.cpp

 /*
  * This file is part of Adblock Plus <http://adblockplus.org/>,
  * Copyright (C) 2006-2013 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
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 #include <AdblockPlus.h>
 #include "AndroidWebRequest.h"
 #include "Utils.h"
 #include "debug.h"
 
 namespace
 {
   std::string ExtractExceptionMessage(JNIEnv* env, jthrowable throwable)
   {
     jclass throwableClass = env->FindClass("java/lang/Throwable");
     jmethodID throwableToStringMethodId = env->GetMethodID(throwableClass, "toString", "()Ljava/lang/String;");
     jstring javaMessage = static_cast<jstring>(env->CallObjectMethod(throwable, throwableToStringMethodId));
-    const char* nativeMessage = env->GetStringUTFChars(javaMessage, 0);
-    const std::string message = nativeMessage;
-    env->ReleaseStringUTFChars(javaMessage, nativeMessage);
-    return message;
+    return "Java exception: " + GetString(env, javaMessage);
   }
 
   class JavaException : public std::exception
   {
   public:
     JavaException(JNIEnv* env)
       : env(env), throwable(env->ExceptionOccurred())
     {
       env->ExceptionClear();
       message = ExtractExceptionMessage(env, throwable);
     }
 
     virtual ~JavaException() throw()
     {
     }
 
     const char* what() const throw()
     {
-      return ("Java Exception: " + message).c_str();

[Wladimir Palant, 2013/11/22 17:51:03]

You are creating a temporary std::string instance here and returning a reference
to its buffer - this will likely crash. You should add "Java Exception: " when
you are initializing the message variable in the constructor, this way there
shouldn't be any trouble.

[Felix Dahlke, 2013/11/22 18:01:12]

Done.

+      return message.c_str();
     }
 
     bool IsInstanceOf(const std::string& className) const
     {
       jclass clazz = env->FindClass(className.c_str());
       if (!clazz)
         return false;
       bool isInstance = env->IsInstanceOf(throwable, clazz);
       env->DeleteLocalRef(clazz);
       return isInstance;
@@ skipping 254 matching lines @@
   {
     D(D_ERROR, "Unknown exception");
     result.status = AdblockPlus::DefaultWebRequest::NS_ERROR_FAILURE;
   }
 
   if (stat == JNI_EDETACHED)
     globalJvm->DetachCurrentThread();
 
   return result;
 }