Addressing crash report involving strlen

[abbeycode]

I got a crash report in UnrarKit in this code:

    const char *filenameData = (const char *) [rarFile UTF8String];
    self.flags->ArcName = new char[strlen(filenameData) + 1]; // <---- Crash here
    strcpy(self.flags->ArcName, filenameData);

I was unable to reproduce, but it seems like since ArcName has a life beyond -_unrarOpenFile:inMode:withPassword:error:, it should be allocated on the heap instead of the stack.