How to access large objects in Postgresql c-language functions?

[Spiros Ioannou <sivann@xxxxxxxxxxxx>]

I'm writing a c-language user defined function for postgresql 9.3.5. I didn't use pl/pgsql or pl/python because part of it needs to be written in C for speed.

The function gets an existing OID as an argument. How can I access & modify the OID data from within the c-language function? I can't find any docs for that! 

Thanks,

-Spiros