vectored g_io_channel_[read|write]_chars?

[Rick Jones <rick jones2 hp com>]

In the netperf4 code I'm porting-over to glib, it used to call sendmsg 
with a two entry iovec - the first entry was the message length, and the 
second was the message body.  The reason to use sendmsg was to present 
logically associated data to the transport at the same time, as one 
really should (must) do for efficient networking.  Setting TCP_NODELAY 
is just a kludge.

At first I figured "Ok, no vectored operations, but there are buffered 
operations and I suppose I can live with the extra copies and having to 
flush"  but I have a question - on Windows a channel is made 
non-blocking when a watch is set (IIRC) - are there any other "gotchas" 
related to that that might make writing unbuffered as well?  I _really_ 
don't want the message length going-out separately from the message 
body... it may not matter all that much for file I/O, but in networking 
that is doubleplusungood.

sincerely,

rick jones