On 13 Mar 2015 16:46, "Alexander Lamaison" <sw...@lammy.co.uk> wrote: > > On 13 Mar 2015 16:18, "Will Cosgrove" <w...@panic.com> wrote: > >> > >> >> we have a function like errorMessageFromCode(int code), the _code_ is the code coming from any o’l libssh function call. > >> > > >> > > >> > But that's the mistake. All libssh2 functions don't return the same error code set. The libssh2_knownhost*() functions for example only return error codes in the LIBSSH2_KNOWNHOST_CHECK_* series. > >> > >> If I may weigh in here, the known_host return codes aren't error codes at all. That's where the misunderstanding has occurred. > >> > >> Most libssh2 return codes are indeed errors. You can think of them as exceptions, in a language that has that feature. Apart from EAGAIN, you never call a libssh2 function expecting to recieve one of those errors. > >> > >> Contrast that with the known_host functions. There the return code is a result, not an error. You call those functions fully expecting to get any of the possible values returned. > > > > I understand these are technically not errors per-say, but that doesn’t mean I agree with their values being the same. > > Would you feel different if the function did a calculation that returned a number? Or checked something and returned a boolean? > > Both those would return values that overlapped with the error codes. But they aren't error codes, so you presumably wouldn't care. The known_hosts functions are no different.
I've thought about this some more and I think I understand where the confusion arises. You are understandably assuming that libssh2_knownhost_check returns error codes when it hits an error (a real, unexpected, exception-type failure; not just 'not found'). It doesn't. It actually return there result FAILURE which means you should call libssh2_session_last_errno function to get the real error code (for example LIBSSH2_ERROR_ALLOC). Alex
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