From mboxrd@z Thu Jan  1 00:00:00 1970
From: Danny Milosavljevic <dannym@scratchpost.org>
Subject: bug#30365: Offloading sometimes hangs
Date: Thu, 15 Feb 2018 01:06:04 +0100
Message-ID: <20180215010604.29cf5694@scratchpost.org>
References: <877erq8med.fsf@gnu.org> <87o9l0zzk1.fsf@gnu.org>
	<87mv0hwy75.fsf@gnu.org>
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To: Ludovic =?UTF-8?Q?Court=C3=A8s?= <ludo@gnu.org>
Cc: 30365-done@debbugs.gnu.org

Hi Ludo,

> On the Guile side, we=E2=80=99ll have to push the fix for
> <https://bugs.gnu.org/30368>.

Can't think of a way to test select.  But can think of a way to test pselec=
t:

Excuse the C:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/select.h>
#include <signal.h>

static void dummy(int signum) {
}

int main() {
        int fds[2];
        struct sigaction sa =3D {
                .sa_handler =3D dummy,
                .sa_flags =3D 0,
        };
        sigemptyset(&sa.sa_mask);
        pipe(fds);
	/* Make sure we don't miss it */
        sigsetmask(sigmask(SIGCHLD));
	/* Make sure we handle it once we DO get it (after unblocking it :P) */
        sigaction(SIGCHLD, &sa, NULL);
        if (fork() =3D=3D 0) {
                _exit(0); /* Cause SIGCHLD (to be at least pending) in the =
parent. */
        } else {
                close(fds[0]);
                fd_set read_set;
                fd_set write_set;
                fd_set except_set;
                sigset_t sigmask;
                int rc;
                FD_ZERO(&read_set);
                FD_ZERO(&write_set);
                FD_SET(fds[1], &write_set);
                FD_ZERO(&except_set);
                sigemptyset(&sigmask); /* unblock SIGCHLD */
                rc =3D pselect(fds[0] + 1, &read_set, &write_set, &except_s=
et, NULL, &sigmask);
                if (rc =3D=3D -1) {
                        perror("select");
                } else if (rc =3D=3D 0) {
                        printf("ZERO\n");
                } else {
                        printf("N\n");
                }
        }
        return 0;
}