Re: 2.5.1: kill(pid, sig) before waitpid() returns -1 for sig != 0

[Corinna Vinschen <corinna-cygwin at cygwin dot com>]

Hi Erik,

On Aug 12 10:44, Erik Bray wrote:
> On Thu, Aug 11, 2016 at 4:13 PM, Corinna Vinschen
> <corinna-cygwin@cygwin.com> wrote:
> > On Aug 11 11:51, Erik Bray wrote:
> >> [...]
> >> In response to the originally issue, this was fixed *specifically* for
> >> the case of kill(pid, 0).  But my reading of the above is that kill()
> >> should return 0 in this case regardless of the signal (modulo
> >> permissions, etc.).  On Linux, for example, when calling kill with pid
> >> of a zombie process the kernel will happily deliver the signal to the
> >> relevant task_struct; it will just never be acted on since the task
> >> will never run again.
> >
> > I'm not sure why cgf only fixed that for sig 0 at the time, since, as
> > you noted, the text from POSIX-1.2008 does not state that this is
> > *restricted* to sig 0.
> 
> Yep, my thoughts exactly.

Funny that nobody noticed at the time, even thought the full POSIX text
was quoted.

> >> The below (untested) patch demonstrates the change I'm suggesting,
> >> though I don't know what other code, if any, might be involved in
> >> this.
> >
> > The original patch laid the groundwork by making sure that there are
> > two states, EXITED and REAPED.  Removing the explicit check for 0 is
> > the right thing to do, afaics, so I tested and applied your patch as is,
> > see
> > https://cygwin.com/git/?p=newlib-cygwin.git;a=commitdiff;h=86f79af827729f3968d8b3b8f860ac29d200da0d
> 
> Thank you so much!  I think this is much better behavior.
> 
> (And thanks for the correction of my name--I'm used to it being
> misspelled but rarely do people notice and correct :)

I belong to the misspelled kind myself (Corrina?  No, Corinna!  Can't
you read?), so I was quite embarrassed when I did it myself :}


Thanks,
Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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