alternative for buggy accept_socket to create a non-blocking version

[Matt Borchers <mattborchers@gmail.com>]

I have no choice but to use an old GNAT compiler -- version 6.3.0.  In this version there is a confirmed bug (fixed in 6.3.2) that prevents the non-blocking version of accept_socket from working.  I want to call the version of accept_socket with the 'timeout' parameter, but it doesn't do what it should.

Basically, I've built a way to read data from a socket and all goes well when a response is made.  However, I need a way to abandon the accept call if a response is never sent within a small time window.

This is my foray into sockets programming and I don't fully understand all of the nuances yet.  I tried setting the Receive_Timeout socket option but it had no effect -- I don't think it does what I need anyway.  This all seems pretty straight-forward assuming there is no bug in the non-blocking version of accept_socket, but I don't know how to work-around this bug.

I can imagine a pair of tasks in which one does the blocking accept (A) and the other task (B) does the time-out.  If the time-out occurs first, B will abort the task A otherwise after A succeeds in accepting the message it will abort B.  This seems like it might not be the best work-around solution.

Does anybody know of a good way to create a type of non-blocking accept_socket?

My code basically is:

with GNAT.Sockets; use GNAT.Sockets;
...
declare
  sock,
  socket   : SOCKET_TYPE;
  address  : SOCK_ADDR_TYPE;
  data     : STREAM_ELEMENT_ARRAY(1..256);
  last     : STREAM_ELEMENT_OFFSET;
  sel_stat : SELECTOR_STATUS;
begin
  create_socket( socket );
  bind_socket( socket, address );
  listen_socket( socket );
  accept_socket( socket, sock, address );
  --I wish I could do this
  --accept_socket( socket, sock, address, timeout => 2.0, status => sel_stat );
  ...
  loop
    receive_socket( sock, data, last );
    ...
  end loop;
  close_socket( socket );
end;

Thanks,
Matt