Editor crashes due to file operations in code

Hi, I have a BlueprintFunctionLibrary I’m writing and some of the code I have is causing the editor to crash on startup.

I have a blueprint-friendly function that does nothing but call a constructor for a separate class and return it.

MyClass MyBlueprintFunction(FString filename) {
   MyClass instance;
   instance = MyClass(TCHAR_TO_ANSI(*filename));
   return instance;

MyClass’ constructor tries to construct itself using information from the file provided.

In the constructor I have the following code:

MyClass(char *filename) {
  FILE *file;
  fopen_s(&file, filename, "rb");  // from stdio.h
  ...  // (using the file)

This code compiles fine in Visual Studio 2015 for development editor. When I use the File* for any operations later in the function, the editor crashes when I start it up. If I remove all uses of the File* the editor does not crash. Some examples of my uses of the File* are as follows:

uint32_t width = 0, height = 0;
fread(&width, 1, sizeof(width), file);
fread(&height, 1, sizeof(height), file);

Leaving any of these lines (except the first) in the function causes the editor to crash. Any ideas of what I might be doing wrong? Is this a bug?

Nope, I added some checking to catch that case and now everything works, thanks!

Are you checking the return of the open function to see if it opened successfully? Or to see if the file pointer is null?