ipa: Change ipa_msg_recv() to support partial receive

Currently ipa_msg_recv() fails, when messages are received partially.

This patch provides a new function ipa_msg_recv_buffered() that uses
an additional ** to a message buffer to store partial data.  When
this happens, -EAGAIN is returned. If NULL is used, the function
behaves similar to ipa_msg_recv() and fails on partial read.
In addition in case of errors the return value is now always -EXXX
and the contents of errno is undefined.

Note that this feature needs support by the calling code insofar that
*tmp_msg must be set to NULL initially and it must be freed and
set to NULL manually when the socket is closed.

Note also that ipa_msg_recv() is then a wrapper around
ipa_msg_recv_buffered() which mimics the old error behaviour by
setting errno explicitely to -rc and returning -1 when an error has
happened.

Ticket: OW#728
Sponsored-by: On-Waves ehf
7 files changed