static int manager_setup_signals(Manager *m) {
        struct sigaction sa = {
                .sa_handler = SIG_DFL,
                .sa_flags = SA_NOCLDSTOP|SA_RESTART,
        };
        sigset_t mask;
        int r;

        assert(m);

        /* We are not interested in SIGSTOP and friends. */
        assert_se(sigaction(SIGCHLD, &sa, NULL) == 0);

        assert_se(sigemptyset(&mask) == 0);

        sigset_add_many(&mask,
                        SIGCHLD,     /* Child died */
                        SIGTERM,     /* Reexecute daemon */
                        SIGHUP,      /* Reload configuration */
                        SIGUSR1,     /* systemd/upstart: reconnect to D-Bus */
                        SIGUSR2,     /* systemd: dump status */
                        SIGINT,      /* Kernel sends us this on control-alt-del */
                        SIGWINCH,    /* Kernel sends us this on kbrequest (alt-arrowup) */
                        SIGPWR,      /* Some kernel drivers and upsd send us this on power failure */
                        SIGRTMIN+0,  /* systemd: start default.target */
                        SIGRTMIN+1,  /* systemd: isolate rescue.target */
                        SIGRTMIN+2,  /* systemd: isolate emergency.target */
                        SIGRTMIN+3,  /* systemd: start halt.target */
                        SIGRTMIN+4,  /* systemd: start poweroff.target */
                        SIGRTMIN+5,  /* systemd: start reboot.target */
                        SIGRTMIN+6,  /* systemd: start kexec.target */
                        SIGRTMIN+13, /* systemd: Immediate halt */
                        SIGRTMIN+14, /* systemd: Immediate poweroff */
                        SIGRTMIN+15, /* systemd: Immediate reboot */
                        SIGRTMIN+16, /* systemd: Immediate kexec */
                        SIGRTMIN+20, /* systemd: enable status messages */
                        SIGRTMIN+21, /* systemd: disable status messages */
                        SIGRTMIN+22, /* systemd: set log level to LOG_DEBUG */
                        SIGRTMIN+23, /* systemd: set log level to LOG_INFO */
                        SIGRTMIN+24, /* systemd: Immediate exit (--user only) */
                        SIGRTMIN+26, /* systemd: set log target to journal-or-kmsg */
                        SIGRTMIN+27, /* systemd: set log target to console */
                        SIGRTMIN+28, /* systemd: set log target to kmsg */
                        SIGRTMIN+29, /* systemd: set log target to syslog-or-kmsg */
                        -1);
        assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);

        m->signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC);
        if (m->signal_fd < 0)
                return -errno;

        r = sd_event_add_io(m->event, m->signal_fd, EPOLLIN, manager_dispatch_signal_fd, m, &m->signal_event_source);
        if (r < 0)
                return r;

        /* Process signals a bit earlier than the rest of things, but
         * later that notify_fd processing, so that the notify
         * processing can still figure out to which process/service a
         * message belongs, before we reap the process. */
        r = sd_event_source_set_priority(m->signal_event_source, -5);
        if (r < 0)
                return r;

        if (m->running_as == SYSTEMD_SYSTEM)
                return enable_special_signals(m);

        return 0;
}
Unknown