SIGPIPE and threads

[John Baldwin]

On Monday 28 June 2010 10:05:34 am Kostik Belousov wrote:
> On Mon, Jun 28, 2010 at 08:33:54AM -0400, John Baldwin wrote:
> > Currently when a thread performs a write(2) on a disconnected socket or a FIFO 
> > with no readers the SIGPIPE signal is posted to the entire process via 
> > psignal().  This means that the signal can be delivered to any thread in the 
> > process.  However, it seems more intuitive to me that SIGPIPE should be sent 
> > to the "offending" thread similar to signals sent in response to traps via 
> > trapsignal().  POSIX seems to require this in that the description of the 
> > EPIPE error return value for write(2) and fflush(3) in the Open Group's online 
> > manpages both say that SIGPIPE should be sent to the current thread in 
> > addition to returning EPIPE:
> > 
> > http://www.opengroup.org/onlinepubs/000095399/functions/write.html
> > 
> > http://www.opengroup.org/onlinepubs/000095399/functions/fflush.html
> > 
> > I have an untested (only compiled) patch below:
>
> I think the patch is right, but, as you note, having a dedicated
> function that wraps automatic ksi initialization and tdsignal()
> call would be even better.

Ok, what I've done is to rename tdsignal() to tdsendsignals() and make it
private to kern_sig.c.  I then added 'tdsignal()' and 'tdksignal()' to the
public KPI to mirror the existing psignal() and pksignal() routines.

This patch can be found at http://www.freebsd.org/~jhb/patches/tdsignal.patch

I then reworked the sigpipe patch to just convert calls to psignal() to
tdsignal() instead.  It is at http://www.freebsd.org/~jhb/patches/sigpipe.patch

-- 
John Baldwin