NT/2k/XP Drivers Development Kit is all what you need. What are those wrappers for ?! If you want to be a friend of the system you have to use standart function for file read/write/open/close operations such as ZwReadFile/ZwWriteFile/ZwOpen/ZwClose. For memory de/allocation you could use ExFreePool/ExAllocatePoolWithTag. For fstat function probably you could use ZwQueryInformationFile.

I'm glad if it is somehow pointed to the source you wanted...