Re: ada/9535: Datagram socket semantics are wrong

[Simon Wright <simon@pushface.org>]

The following reply was made to PR ada/9535; it has been noted by GNATS.

From: Simon Wright <simon@pushface.org>
To: gcc-gnats@gcc.gnu.org,  gcc-bugs@gcc.gnu.org,  nobody@gcc.gnu.org, 
 simon@pushface.org,  gcc-prs@gcc.gnu.org
Cc:  
Subject: Re: ada/9535: Datagram socket semantics are wrong
Date: Sat, 01 Mar 2003 07:57:02 +0000

 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=9535
 
 A clarification (I hope):
 
 At present, you can't use 'Read, 'Write with Stream(UDP_Socket) at all 
 (except for
 elementary types). You can Write a Stream_Element_Array, but you can't 
 Read one unless
 you know beforehand how big it needs to be. The patch I sent allows you 
 to Read into an
 arbitrarily-sized Stream_Element_Array, but you still can't do 'Read, 
 'Write directly.
 
 It's at least arguable that users should not be able to get a Stream at 
 all for a UDP socket (use
 Receive_Socket, Send_Socket instead). That solution would cause us 
 problems on the
 writing side: to avoid multiple OS calls, we
    get the user to stream his data into a memory stream
    get the user to write the contents of the memory stream to your 
 socket's stream in one go.
 
 On the UDP read side (using unpatched GNAT), we
    Receive_Socket into a memory stream
    give the user our memory stream to read from rather than your 
 socket's stream.