Daniel Stenberg <[EMAIL PROTECTED]> writes:
> On Tue, 1 Jul 2008, J.T. Conklin wrote:
>
>> I checked the current CVS version of sftp.c, and it looks like more
>> effort has been made to make libssh2_sftp_close_handle() return
>> PACKET_EAGAIN when an underlying libssh_* operation fails with
>> PACKET_EAGAIN. I'm not sure what benefit this is supposed to
>> provide. It seems to push error handling for nonblocking
>> connections up to the client, so what was a
>> "libssh2_sftp_close_handle(h);" has to be changed to
>> "while(libssh2_sftp_close_handle(h) != PACKET_EAGAIN);".
>>
>> I really think this libssh2_sftp_close_handle() needs to be changed
>> to be best effort and blocking
>
> Why so? We've made an effort to bring non-blocking functionality to
> libssh2, why would an application using libssh2 suddenly not care
> about that when it wants to close a SFTP handle?
I suggested blocking because it seems conceptually simpler. After you
close a handle, there's nothing more that can be done with it, as such
it seemed natural to have close() block until it has completed? Now I
suspect this opinion was formed due to my lack of direct experience
with non-blocking I/O -- I usually use blocking or asynchronous I/O.
I did a little investigating, and saw that OpenSSL's SSL_shutdown(),
which is roughly equivalent in a handwavy kind of way, also returns a
"partially done" value when the BIO is in nonblocking mode. It seems
that libssh2's behavior isn't as wierd as I first thought, and I'll
take that suggestion off the table (and we can all pretend I never
made it in the first place :-).
But if there is a hard failure, as in the case of the underlying
connection being closed, I think libssh2_sftp_close_handle() has to
complete, as no amount of retries are going to complete the close.
--jtc
--
J.T. Conklin
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