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Re: [libvirt] [PATCH] Fix sending/receiving of FDs when stream returns EAGAIN

On 11/04/2011 10:06 AM, Daniel P. Berrange wrote:
From: "Daniel P. Berrange"<berrange redhat com>

The code calling sendfd/recvfd was mistakenly assuming those
calls would never block. They can in fact return EAGAIN and
this is causing us to drop the client connection when blocking
ocurrs while sending/receiving FDs.

Fixing this is a little hairy on the incoming side, since at
the point where we see the EAGAIN, we already thought we had
finished receiving all data for the packet. So we play a little
trick to reset bufferOffset again and go back into polling for
more data.

* src/rpc/virnetsocket.c, src/rpc/virnetsocket.h: Update
   virNetSocketSendFD/RecvFD to return 0 on EAGAIN, or 1
   on success
* src/rpc/virnetclient.c: Move decoding of header&  fds
   out of virNetClientCallDispatch and into virNetClientIOHandleInput.
   Handling blocking when sending/receiving FDs
* src/rpc/virnetmessage.h: Add a 'donefds' field to track
   how many FDs we've sent / received
* src/rpc/virnetserverclient.c: Handling blocking when
   sending/receiving FDs

ACK - the solution matches the commit message, which does sound like the correct way to handle things; and I didn't see anything wrong in the patch. Appropriate for 0.9.7.

Eric Blake   eblake redhat com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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