[ECOS] New revision of select() hangs my code

[Dan Jakubiec <dan at systech dot com>]

> I just grabbed the latest version of
> ecos/packages/io/fileio/current/src/select.cxx (I went from rev 1.8 to
> 1.9).  The changes in this file break my current code which uses the
> select() call.  I looked through the code changes, but didn't see anything
> obviously wrong.
> 
> Nick Garnett:  Would you mind having a look at this to see if you can see
> something?
> 
> My code just issues a select() call with a timeout of 0 to poll the read
> state of a TCP socket.  Here is the gist of what my code does:
> 
> void my_func()
> {
> 	fd_set read_fds;
> 	struct timeval timeout;
> 	int s;	/* TCP socket */
> 	int net_ok;
> 	char buf[128];
> 
> 	/* The "s" file descriptor is a connected TCP socket */
> 	...
> 
> 	FD_ZERO(&read_fds);
> 	FD_SET(s, &read_fds);
> 	timeout.tv_sec = timeout.tv_usec = 0;
> 	net_ok = TRUE;
> 	while (net_ok &&
> 		(select(s+1, &read_fds, NULL, NULL, &timeout) > 0) &&
> 		FD_ISSET(s, &read_fds))
> 	{
> 		diag_printf("got data\n");
> 		net_ok = (read(s, buf, sizeof(buf)) > 0);
> 
> 	}
> 	diag_printf("Finished flushing data\n");
> 
> }
> 
> 
> With revision 1.8 of select.cxx, the code works fine (ie. it returns
> immediately with the socket state).  With revision 1.9 of select.cxx, the
> select() call hangs on the first call and does not return (ie. neither of
> my diag_printf()'s come out).  Any ideas?
> 
> --
> Dan Jakubiec
> Systech Corporation
> dan@systech.com
> 

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