Re: [Qemu-devel] [PATCH] suppress 'warn_unused_result' warning

[Stuart Brady]

On Sun, May 10, 2009 at 07:53:35PM -0600, M. Warner Losh wrote:
> When a signal is received and you are waiting for data, you get
> EINTR.  If there's data available, then I believe the behavior is to
> return that data and not EINTR.  That's the way Unix works.

So if I do a read() from a file over NFS, and there's an awful lot of
latency (and perhaps even connection problems), and the process gets a
signal -- does that mean that the signal will only be delivered once
data is returned?

If not, then I would really start to wonder whether /all/ code dealing
with read(), write(), etc. should be written to cope with EINTR (and 
also partial reads/writes?) regardless of whatever is done with threads
and signal masks, as doing otherwise seems only to be asking for trouble
at some point.  (I'd be especially concerned about signals intended for
libraries that are not under the developer's control...)
-- 
Stuart Brady