Re: ada/9535: Datagram socket semantics are wrong

Re: ada/9535: Datagram socket semantics are wrong

[Dara Hazeghi]

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

From: Dara Hazeghi <dhazeghi@yahoo.com>
To: gcc-bugs@gcc.gnu.org, gcc-gnats@gcc.gnu.org, simon@pushface.org
Cc:  
Subject: Re: ada/9535: Datagram socket semantics are wrong
Date: Mon, 12 May 2003 17:34:34 -0700

 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit- 
 trail&database=gcc&pr=9535
 
 Hello,
 
 you'll probably have better luck getting feedback, if you send this  
 patch to either the gcc-patches mailing lists, or one of the Ada  
 maintainers. To date, Ada people haven't paid much attention to bug  
 reports in GNATs. Cheers,
 
 Dara
 

Re: ada/9535: Datagram socket semantics are wrong

[Simon Wright]

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.
 
 

ada/9535: Datagram socket semantics are wrong

[simon]

>Number:         9535
>Category:       ada
>Synopsis:       Datagram socket semantics are wrong
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Feb 01 18:06:01 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator:     Simon Wright
>Release:        gcc version 3.4 20030201 (experimental)
>Organization:
>Environment:
i686-pc-linux-gnu
>Description:
Datagram sockets try to behave like streams -- they will send as many datagrams as necessary to output the data rather than failing if the user sends more than the max datagram size, and read as many as necessary to fill the user buffer.
I believe they should respect the "datagram-ness" of the medium the user has chosen. There are all sorts of problems with the present model (out-of-order arrival etc).
I propose the attached patch.
>How-To-Repeat:
Not applicable.
>Fix:
As per patch.
>Release-Note:
>Audit-Trail:
>Unformatted:
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