On Thu, Aug 11, 2016 at 4:13 PM, Corinna Vinschen <corinna-cyg...@cygwin.com> wrote: > Hi Eric, > > On Aug 11 11:51, Erik Bray wrote: >> [...] >> > Existing implementations vary on the result of a kill() with pid >> > indicating an inactive process (a >> > terminated process that has not been waited for by its parent). Some >> > indicate success on such a >> > call (subject to permission checking), while others give an error of >> > [ESRCH]. Since the definition >> > of process lifetime in this volume of POSIX.1-2008 covers inactive >> > processes, the [ESRCH] error >> > as described is inappropriate in this case. In particular, this means that >> > an application cannot >> > have a parent process check for termination of a particular child with >> > kill(). (Usually this is done >> > with the null signal; this can be done reliably with waitpid().) >> >> 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. >> 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 :) Best, Erik -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
