Internals of Feature API

Modules
	Internal Cryptographic Backend
	Policy instantiation module
	Policy calculation module
	Policy callback functions.
	Policy execution functions.
	Policy utilitiy module
	Helper functions module
	Utility module
	Basic IO module
	Key store module
	Policy store module
	Configuration utilities.
	Event log utilities.
	Profile module
	FAPI object serialization module
	FAPI object deserialization module
	Vendor specific module

Detailed Description

This module holds internal APIs of the FAPI implementation.

Async programming style:

The tss2-fapi implementation uses an asynchronous programming style internally. This means that whenever a piece of code performs a potentially blocking operation it will instead return TSS2_FAPI_RC_TRY_AGAIN (similarly to ESAPI). Then this function is called again once the Poll returns ok. In order to carry the state of execution information over between the different invocation of the same function, the current state is stored in a state variable and all variables are stored in some kind of context variables. On the next entry to the function the state is evaluated using a swtich() statement and execution is resumed.

In order to understand the functional flow of code in FAPI, one can read the functions continuously over all fallthrough; and statecase(); statements. The statecase statements are the re-entry points of each function. The return_try_again() and FAPI_SYNC() statements are the preempt statements.