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Groups > gnu.bash.bug > #15963

Re: "wait" loses signals

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On 2/24/20 5:18 PM, Chet Ramey wrote:
> The first case is trickier: there's always going to be a window between
> the time the shell checks for pending traps and the time the wait builtin
> starts to run. You can't really close it unless you're willing to run the
> trap out of the signal handler, which everyone agrees is a bad idea, but
> you can squeeze it down to practially nothing.

dash uses something along these lines:

         sigfillset(&mask);
         sigprocmask(SIG_SETMASK, &mask, &mask);
         while (!pending_sig)
                 sigsuspend(&mask);
         sigprocmask(SIG_SETMASK, &mask, NULL);
         if (pending_sig)
                 handle_signals(pending_sig);
         pid = waitpid(... WNOHANG);

It sleeps in sigsuspend(), not in waitpid(). This way we wait for both
signals *and* children (by virtue of getting SIGCHLD for them).

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Re: "wait" loses signals Denys Vlasenko <dvlasenk@redhat.com> - 2020-02-24 18:19 +0100

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