Re: [PATCH] ada/9535: Do not loop when writing/reading on datagram socket

[Samuel Tardieu <sam at rfc1149 dot net>]

On 16/04, Laurent GUERBY wrote:

| > +      Send_Socket
| > +        (Stream.Socket,
| > +         Item,
| > +         Last,
| > +         Stream.To);
[...]
| > +      if Last /= Item'Last then
| >           raise Socket_Error;
| >        end if;
| 
| IIRC the data payload of an UDP datagram can be zero (to be checked I
| might be wrong), in this case Send_Socket will set Last to Item'First
| and the "if" above will erroneously raise Socket_Error because Last =
| Item'First /= Item'Last by construction of empty array bounds in Ada.
| 
| Might be a thing to try out as there might be similar handling
| of zero elsewhere.

I don't think so: in "Send_Socket", "Last" is set to
      Item'First + Ada.Streams.Stream_Element_Offset (Res - 1);
where "Res" is the number of bytes sent; this will correctly give
"Item'First - 1" if an empty payload has been succesfully sent.

Where did you see that "Send_Socket" would set "Last" to "Item'First"?