Simplify signMessageJni

java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_account.cpp

@@ -413,17 +413,18 @@ JNIEXPORT jstring OLM_ACCOUNT_FUNC_DEF(signMessageJni)(JNIEnv *env, jobject thiz
   else
   {
     int messageLength = env->GetArrayLength(aMessage);
-        unsigned char* messageToSign = new unsigned char[messageLength];
-        env->GetByteArrayRegion(aMessage, 0, messageLength, reinterpret_cast<jbyte*>(messageToSign));
+    jbyte* messageToSign = env->GetByteArrayElements(aMessage, NULL);
 
     // signature memory allocation
     signatureLength = olm_account_signature_length(accountPtr);
+
     if(NULL == (signedMsgPtr = (void*)malloc((signatureLength+1)*sizeof(uint8_t))))
     {
       LOGE("## signMessageJni(): failure - signature allocation OOM");
     }
     else
-        {   // sign message
+    {
+      // sign message
       resultSign = olm_account_sign(accountPtr,
                                    (void*)messageToSign,
                                    (size_t)messageLength,
@@ -446,15 +447,15 @@ JNIEXPORT jstring OLM_ACCOUNT_FUNC_DEF(signMessageJni)(JNIEnv *env, jobject thiz
     }
 
     // release messageToSign
-        free(messageToSign);
+    if (messageToSign)
+    {
+      env->ReleaseByteArrayElements(aMessage, messageToSign, JNI_ABORT);
+    }
   }
 
   return signedMsgRetValue;
 }
 
-
-
-
 /**
 * Serialize and encrypt account instance into a base64 string.<br>
 * @param aKey key used to encrypt the serialized account data