#GenericPlatformFile.h
I offered the functionality you are wanting as a pull request to Epic but they did not seem to think it was necessary
You can see all the available file functions here:
GenericPlatformFile.h
If you still think the Engine needs this functionality then maybe you can support another pull request that I make to bring this functionality to the engine.
I have a wiki on how to use GeneralPlatformfile here: