From a perfectionist viewpoint, the decision's almost correct: TLS work on streams and fds are streams in POSIX. Although an ANSI C's FILE* would be a more port

From a perfectionist viewpoint, the decision's almost correct: TLS work on streams and fds are streams in POSIX. Although an ANSI C's FILE* would be a more portable thus wiser choice. However, given that the world's flawed and FILEs (and fds) aren't proper objects that end-user can create and use with their own functions (like an implementation of read(2) that'd yield to an event loop until the data's there), guess it warrants yet another ad-hoc struct. Or a bunch of functions that work on some context struct and that you're supposed to pass data chunks by yourself. Like in classic OpenSSL API.