[fpc-devel] Linux Signals

Mark Morgan Lloyd markMLl.fpc-devel at telemetry.co.uk
Sat Jan 1 19:02:47 CET 2011

Andrew Brunner wrote:
> I'm trying to get signals to work with sockets under x64 Ubuntu 10.10
> (all updates)
> I installed two handlers for two events SIGIO, and SIGHUP uising
> fpsigaction(SIGIO, @saAct, nil) .  I was expecting to get a byte by
> byte signal under telnet to my server instance (110-pop3) on the IO
> but had only received the signal on CRLF.  Firefox on the HTTP has the
> same problem but I suspect a problem since it is impossible to ever
> receive a signal for binary protocols having no CRLFs for as kernel
> triggers to signal applications. Perhaps this particular issue is
> better directed at Debian?

I am neither a kernel hacker nor a network guru, but would a signal be 
raised when a byte was read or when a TCP packet- possibly comprising 
aggregated bytes- was transferred? I think you'd be better not using a 
standard telnet client for this but instead using Netcat (nc) or 
netpipes (faucet and hose) which will not, certainly by default, be 
fiddling with line-ends or aggregating bytes for efficiency.

Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]

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