provide freeBufferCallback to Nan::NewBuffer to fix imencode crashes in electron when buffer is released

Author: justadudewhohacks

cc/modules/io/ioBindings.h

@@ -10,57 +10,57 @@ namespace IoBindings {
     std::string path;
     int flags = cv::IMREAD_COLOR;
     cv::Mat img;
-  
+
     std::string executeCatchCvExceptionWorker() {
       img = cv::imread(path, flags);
       if (img.rows == 0 && img.cols == 0) {
         return "empty Mat";
       }
       return "";
     }
-  
+
     bool unwrapRequiredArgs(Nan::NAN_METHOD_ARGS_TYPE info) {
       return StringConverter::arg(0, &path, info);
     }
-  
+
     bool unwrapOptionalArgs(Nan::NAN_METHOD_ARGS_TYPE info) {
       return IntConverter::optArg(1, &flags, info);
     }
-  
+
     FF_VAL getReturnValue() {
       return Mat::Converter::wrap(img);
     }
   };
-  
+
   struct ImwriteWorker : CatchCvExceptionWorker {
   public:
     std::string path;
     cv::Mat img;
     std::vector<int> flags;
-  
+
     std::string executeCatchCvExceptionWorker() {
       cv::imwrite(path, img);
       return "";
     }
-  
+
     bool unwrapRequiredArgs(Nan::NAN_METHOD_ARGS_TYPE info) {
       return StringConverter::arg(0, &path, info)
         || Mat::Converter::arg(1, &img, info);
     }
-  
+
     bool unwrapOptionalArgs(Nan::NAN_METHOD_ARGS_TYPE info) {
       return IntArrayConverter::optArg(2, &flags, info);
     }
   };
-  
+
   struct ImencodeWorker : CatchCvExceptionWorker {
   public:
     std::string ext;
     cv::Mat img;
     std::vector<int> flags;
     char *data;
     size_t dataSize;
-  
+
     std::string executeCatchCvExceptionWorker() {
       std::vector<uchar> dataVec;
       cv::imencode(ext, img, dataVec, flags);
@@ -69,40 +69,44 @@ namespace IoBindings {
       memcpy(data, reinterpret_cast<char*>(dataVec.data()), dataSize);
       return "";
     }
-  
+
     bool unwrapRequiredArgs(Nan::NAN_METHOD_ARGS_TYPE info) {
       return StringConverter::arg(0, &ext, info)
         || Mat::Converter::arg(1, &img, info);
     }
-  
+
     bool unwrapOptionalArgs(Nan::NAN_METHOD_ARGS_TYPE info) {
       return IntArrayConverter::optArg(2, &flags, info);
     }
-  
+
+    static void freeBufferCallback(char* data, void* hint) {
+      free(data);
+    }
+
     FF_VAL getReturnValue() {
-      return Nan::NewBuffer(data, dataSize).ToLocalChecked();
+      return Nan::NewBuffer(data, dataSize, freeBufferCallback, 0).ToLocalChecked();
     }
   };
-  
+
   struct ImdecodeWorker : CatchCvExceptionWorker {
   public:
     int flags;
     cv::Mat img;
     char *data;
     size_t dataSize;
-  
+
     std::string executeCatchCvExceptionWorker() {
       std::vector<uchar> vec(dataSize);
       memcpy(vec.data(), data, dataSize);
       img = cv::imdecode(vec, flags);
       return "";
     }
-  
+
     FF_VAL getReturnValue() {
       return Mat::Converter::wrap(img);
     }
   };
-  
+
 
 }