Re: [RFC] EINTR and PC loser-ing library design

[Rich Felker <dalias@libc.org>]

On Mon, Dec 08, 2014 at 03:45:33PM +0100, Laurent Bercot wrote:
> On 08/12/2014 15:32, Rich Felker wrote:
> 
> >The system call restarts (or, formally, it's as if it were never
> >interrupted; EINTR only applies to signal _handlers_).
> 
>  Could you please provide a pointer to the specification that
> guarantees this ? I've never been able to find a normative text that
> ensures you will never get EINTR unless you explicitly install a
> signal handler without SA_RESTART.

I've had a hard time pinning it down too, but that's what all modern
(e.g. modern enough to have a working sigaction) implementations do,
and it's the obviously correct behavior. I would consider making a
request for clarification here, but after what happened with the C
locale issue, I'd kinda fear some trolls would appear and insist that
EINTR be allowed to happen for no good reason. :(

> >>  And that happens all the time in asynchronous event loops where you
> >>handle signals with a self-pipe. ;)
> >
> >Only if you have installed interrupting signal handlers.
> 
>  Which basically means any signal except SIGCHLD.

No. Interrupting means "installed without SA_RESTART". It has nothing
to do with which signal it is, but rather how you installed the
handler.

Rich