RE: pselect/etc semantics

[David Laight]

From: Eric W. Biederman
> Sent: 30 May 2019 16:38
> ebiederm@xxxxxxxxxxxx (Eric W. Biederman) writes:
> 
> > Which means I believe we have a semantically valid change in behavior
> > that is causing a regression.
> 
> I haven't made a survey of all of the functions yet but
> fucntions return -ENORESTARTNOHAND will never return -EINTR and are
> immune from this problem.

Eh?
ERESTARTNOHAND just makes the system call restart if there is no
signal handler, EINTR should still be returned if there is a handler.

All the functions that have a temporary signal mask are likely
to be expected to work the same way and thus have the same bugs.

http://pubs.opengroup.org/onlinepubs/9699919799/functions/pselect.html#
isn't overly helpful.
But I think it should return EINTR even if there is no handler unless
SA_RESTART is set:

[EINTR]
    The function was interrupted while blocked waiting for any of the selected descriptors to become ready and before the timeout interval expired.

    If SA_RESTART has been set for the interrupting signal, it is implementation-defined whether the function restarts or returns with [EINTR].

	David

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