C++ sd_event_add_io函数代码示例

int button_open(Button *b) {
        char *p, name[256];
        int r;

        assert(b);

        b->fd = safe_close(b->fd);

        p = strjoina("/dev/input/", b->name);

        b->fd = open(p, O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
        if (b->fd < 0)
                return log_warning_errno(errno, "Failed to open %s: %m", b->name);

        if (ioctl(b->fd, EVIOCGNAME(sizeof(name)), name) < 0) {
                r = log_error_errno(errno, "Failed to get input name: %m");
                goto fail;
        }

        r = sd_event_add_io(b->manager->event, &b->io_event_source, b->fd, EPOLLIN, button_dispatch, b);
        if (r < 0) {
                log_error_errno(r, "Failed to add button event: %m");
                goto fail;
        }

        log_info("Watching system buttons on /dev/input/%s (%s)", b->name, name);

        return 0;

fail:
        b->fd = safe_close(b->fd);
        return r;
}

static int automount_coldplug(Unit *u) {
        Automount *a = AUTOMOUNT(u);
        int r;

        assert(a);
        assert(a->state == AUTOMOUNT_DEAD);

        if (a->deserialized_state != a->state) {

                r = open_dev_autofs(u->manager);
                if (r < 0)
                        return r;

                if (a->deserialized_state == AUTOMOUNT_WAITING ||
                    a->deserialized_state == AUTOMOUNT_RUNNING) {

                        assert(a->pipe_fd >= 0);

                        r = sd_event_add_io(u->manager->event, a->pipe_fd, EPOLLIN, automount_dispatch_io, u, &a->pipe_event_source);
                        if (r < 0)
                                return r;
                }

                automount_set_state(a, a->deserialized_state);
        }

        return 0;
}

_public_ int sd_lldp_start(sd_lldp *lldp) {
        int r;

        assert_return(lldp, -EINVAL);

        if (lldp->fd >= 0)
                return 0;

        assert(!lldp->io_event_source);

        lldp->fd = lldp_network_bind_raw_socket(lldp->ifindex);
        if (lldp->fd < 0)
                return lldp->fd;

        if (lldp->event) {
                r = sd_event_add_io(lldp->event, &lldp->io_event_source, lldp->fd, EPOLLIN, lldp_receive_datagram, lldp);
                if (r < 0)
                        goto fail;

                r = sd_event_source_set_priority(lldp->io_event_source, lldp->event_priority);
                if (r < 0)
                        goto fail;

                (void) sd_event_source_set_description(lldp->io_event_source, "lldp-io");
        }

        return 1;

fail:
        lldp->io_event_source = sd_event_source_unref(lldp->io_event_source);
        lldp->fd = safe_close(lldp->fd);

        return r;
}

static int dns_transaction_emit(DnsTransaction *t) {
        int r;

        assert(t);

        if (t->scope->protocol == DNS_PROTOCOL_DNS && !t->server) {
                DnsServer *server = NULL;
                _cleanup_close_ int fd = -1;

                fd = dns_scope_udp_dns_socket(t->scope, &server);
                if (fd < 0)
                        return fd;

                r = sd_event_add_io(t->scope->manager->event, &t->dns_udp_event_source, fd, EPOLLIN, on_dns_packet, t);
                if (r < 0)
                        return r;

                t->dns_udp_fd = fd;
                fd = -1;
                t->server = dns_server_ref(server);
        }

        r = dns_scope_emit(t->scope, t->dns_udp_fd, t->sent);
        if (r < 0)
                return r;

        return 0;
}

static int busname_watch_fd(BusName *n) {
        int r;

        assert(n);

        if (n->starter_fd < 0)
                return 0;

        if (n->starter_event_source) {
                r = sd_event_source_set_enabled(n->starter_event_source, SD_EVENT_ON);
                if (r < 0)
                        goto fail;
        } else {
                r = sd_event_add_io(UNIT(n)->manager->event, &n->starter_event_source, n->starter_fd, EPOLLIN, busname_dispatch_io, n);
                if (r < 0)
                        goto fail;

                (void) sd_event_source_set_description(n->starter_event_source, "busname-starter");
        }

        return 0;

fail:
        log_unit_warning_errno(UNIT(n), r, "Failed to watch starter fd: %m");
        busname_unwatch_fd(n);
        return r;
}

void DbusApiInit(int sock)
{
	fd = sock;
	sd_event_source *busSource = NULL;
	sd_bus_slot *slot = NULL;

	int ret = sd_event_default(&event);
	char tmp = '0';
	read(fd, &tmp, sizeof(char));

	ret = sd_bus_open_system(&bus);

	ret = sd_bus_add_object_vtable(bus, &slot, "/org/watchdogd1",
				"org.watchdogd1", watchdogPmon, NULL);

	ret = sd_bus_request_name(bus, "org.watchdogd1", 0);

	if (ret < 0) {
		ReloadDbusDaemon();
		ret = sd_bus_request_name(bus, "org.watchdogd1", 0);
	}

	sd_event_add_io(event, &busSource, sd_bus_get_fd(bus), EPOLLIN, BusHandler, NULL);

	sd_event_loop(event);
}

static int automount_coldplug(Unit *u) {
        Automount *a = AUTOMOUNT(u);
        int r;

        assert(a);
        assert(a->state == AUTOMOUNT_DEAD);

        if (a->deserialized_state != a->state) {

                r = open_dev_autofs(u->manager);
                if (r < 0)
                        return r;

                if (a->deserialized_state == AUTOMOUNT_WAITING ||
                    a->deserialized_state == AUTOMOUNT_RUNNING) {
                        assert(a->pipe_fd >= 0);

                        r = sd_event_add_io(u->manager->event, &a->pipe_event_source, a->pipe_fd, EPOLLIN, automount_dispatch_io, u);
                        if (r < 0)
                                return r;

                        (void) sd_event_source_set_description(a->pipe_event_source, "automount-io");
                        if (a->deserialized_state == AUTOMOUNT_RUNNING) {
                                r = automount_start_expire(a);
                                if (r < 0)
                                        log_unit_warning_errno(UNIT(a), r, "Failed to start expiration timer, ignoring: %m");
                        }
                }

                automount_set_state(a, a->deserialized_state);
        }

        return 0;
}

int raw_export_start(RawExport *e, const char *path, int fd, ImportCompressType compress) {
        _cleanup_close_ int sfd = -1, tfd = -1;
        int r;

        assert(e);
        assert(path);
        assert(fd >= 0);
        assert(compress < _IMPORT_COMPRESS_TYPE_MAX);
        assert(compress != IMPORT_COMPRESS_UNKNOWN);

        if (e->output_fd >= 0)
                return -EBUSY;

        r = fd_nonblock(fd, true);
        if (r < 0)
                return r;

        r = free_and_strdup(&e->path, path);
        if (r < 0)
                return r;

        sfd = open(path, O_RDONLY|O_CLOEXEC|O_NOCTTY);
        if (sfd < 0)
                return -errno;

        if (fstat(sfd, &e->st) < 0)
                return -errno;
        r = stat_verify_regular(&e->st);
        if (r < 0)
                return r;

        /* Try to take a reflink snapshot of the file, if we can t make the export atomic */
        tfd = reflink_snapshot(sfd, path);
        if (tfd >= 0)
                e->input_fd = TAKE_FD(tfd);
        else
                e->input_fd = TAKE_FD(sfd);

        r = import_compress_init(&e->compress, compress);
        if (r < 0)
                return r;

        r = sd_event_add_io(e->event, &e->output_event_source, fd, EPOLLOUT, raw_export_on_output, e);
        if (r == -EPERM) {
                r = sd_event_add_defer(e->event, &e->output_event_source, raw_export_on_defer, e);
                if (r < 0)
                        return r;

                r = sd_event_source_set_enabled(e->output_event_source, SD_EVENT_ON);
        }
        if (r < 0)
                return r;

        e->output_fd = fd;
        return r;
}

static int stdout_stream_install(Server *s, int fd, StdoutStream **ret) {
        _cleanup_(stdout_stream_freep) StdoutStream *stream = NULL;
        sd_id128_t id;
        int r;

        assert(s);
        assert(fd >= 0);

        r = sd_id128_randomize(&id);
        if (r < 0)
                return log_error_errno(r, "Failed to generate stream ID: %m");

        stream = new0(StdoutStream, 1);
        if (!stream)
                return log_oom();

        stream->fd = -1;
        stream->priority = LOG_INFO;

        xsprintf(stream->id_field, "_STREAM_ID=" SD_ID128_FORMAT_STR, SD_ID128_FORMAT_VAL(id));

        r = getpeercred(fd, &stream->ucred);
        if (r < 0)
                return log_error_errno(r, "Failed to determine peer credentials: %m");

        if (mac_selinux_use()) {
                r = getpeersec(fd, &stream->label);
                if (r < 0 && r != -EOPNOTSUPP)
                        (void) log_warning_errno(r, "Failed to determine peer security context: %m");
        }

        (void) shutdown(fd, SHUT_WR);

        r = sd_event_add_io(s->event, &stream->event_source, fd, EPOLLIN, stdout_stream_process, stream);
        if (r < 0)
                return log_error_errno(r, "Failed to add stream to event loop: %m");

        r = sd_event_source_set_priority(stream->event_source, SD_EVENT_PRIORITY_NORMAL+5);
        if (r < 0)
                return log_error_errno(r, "Failed to adjust stdout event source priority: %m");

        stream->fd = fd;

        stream->server = s;
        LIST_PREPEND(stdout_stream, s->stdout_streams, stream);
        s->n_stdout_streams++;

        if (ret)
                *ret = stream;

        stream = NULL;

        return 0;
}

int sd_pppoe_start(sd_pppoe *ppp) {
        union sockaddr_union link = {
                .ll = {
                        .sll_family = AF_PACKET,
                        .sll_protocol = htons(ETH_P_PPP_DISC),
                },
        };
        _cleanup_close_ int s = -1;
        _cleanup_event_source_unref_ sd_event_source *io = NULL;
        int r;

        assert_return(ppp, -EINVAL);
        assert_return(ppp->fd == -1, -EBUSY);
        assert_return(!ppp->io, -EBUSY);
        assert_return(ppp->ifindex > 0, -EUNATCH);
        assert_return(ppp->ifname, -EUNATCH);
        assert_return(ppp->event, -EUNATCH);
        assert_return(ppp->cb, -EUNATCH);

        s = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
        if (s < 0)
                return -errno;

        link.ll.sll_ifindex = ppp->ifindex;

        r = bind(s, &link.sa, sizeof(link.ll));
        if (r < 0)
                return r;

        r = sd_event_add_io(ppp->event, &io,
                            s, EPOLLIN, pppoe_receive_message,
                            ppp);
        if (r < 0)
                return r;

        r = sd_event_source_set_priority(io, ppp->event_priority);
        if (r < 0)
                return r;

        ppp->fd = s;
        s = -1;
        ppp->io = io;
        io = NULL;

        r = pppoe_send_initiation(ppp);
        if (r < 0)
                return r;

        ppp->state = PPPOE_STATE_INITIALIZING;

        return 0;
}

int server_open_native_socket(Server*s) {

        static const union sockaddr_union sa = {
                .un.sun_family = AF_UNIX,
                .un.sun_path = "/run/systemd/journal/socket",
        };
        static const int one = 1;
        int r;

        assert(s);

        if (s->native_fd < 0) {
                s->native_fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
                if (s->native_fd < 0)
                        return log_error_errno(errno, "socket() failed: %m");

                (void) unlink(sa.un.sun_path);

                r = bind(s->native_fd, &sa.sa, SOCKADDR_UN_LEN(sa.un));
                if (r < 0)
                        return log_error_errno(errno, "bind(%s) failed: %m", sa.un.sun_path);

                (void) chmod(sa.un.sun_path, 0666);
        } else
                fd_nonblock(s->native_fd, 1);

        r = setsockopt(s->native_fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one));
        if (r < 0)
                return log_error_errno(errno, "SO_PASSCRED failed: %m");

#ifdef HAVE_SELINUX
        if (mac_selinux_use()) {
                r = setsockopt(s->native_fd, SOL_SOCKET, SO_PASSSEC, &one, sizeof(one));
                if (r < 0)
                        log_warning_errno(errno, "SO_PASSSEC failed: %m");
        }
#endif

        r = setsockopt(s->native_fd, SOL_SOCKET, SO_TIMESTAMP, &one, sizeof(one));
        if (r < 0)
                return log_error_errno(errno, "SO_TIMESTAMP failed: %m");

        r = sd_event_add_io(s->event, &s->native_event_source, s->native_fd, EPOLLIN, server_process_datagram, s);
        if (r < 0)
                return log_error_errno(r, "Failed to add native server fd to event loop: %m");

        r = sd_event_source_set_priority(s->native_event_source, SD_EVENT_PRIORITY_NORMAL+5);
        if (r < 0)
                return log_error_errno(r, "Failed to adjust native event source priority: %m");

        return 0;
}

int server_open_dev_kmsg(Server *s) {
        mode_t mode;
        int r;

        assert(s);

        if (s->read_kmsg)
                mode = O_RDWR|O_CLOEXEC|O_NONBLOCK|O_NOCTTY;
        else
                mode = O_WRONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY;

        s->dev_kmsg_fd = open("/dev/kmsg", mode);
        if (s->dev_kmsg_fd < 0) {
                log_full(errno == ENOENT ? LOG_DEBUG : LOG_WARNING,
                         "Failed to open /dev/kmsg, ignoring: %m");
                return 0;
        }

        if (!s->read_kmsg)
                return 0;

        r = sd_event_add_io(s->event, &s->dev_kmsg_event_source, s->dev_kmsg_fd, EPOLLIN, dispatch_dev_kmsg, s);
        if (r < 0) {

                /* This will fail with EPERM on older kernels where
                 * /dev/kmsg is not readable. */
                if (r == -EPERM) {
                        r = 0;
                        goto fail;
                }

                log_error_errno(r, "Failed to add /dev/kmsg fd to event loop: %m");
                goto fail;
        }

        r = sd_event_source_set_priority(s->dev_kmsg_event_source, SD_EVENT_PRIORITY_IMPORTANT+10);
        if (r < 0) {
                log_error_errno(r, "Failed to adjust priority of kmsg event source: %m");
                goto fail;
        }

        s->dev_kmsg_readable = true;

        return 0;

fail:
        s->dev_kmsg_event_source = sd_event_source_unref(s->dev_kmsg_event_source);
        s->dev_kmsg_fd = safe_close(s->dev_kmsg_fd);

        return r;
}

static int connection_enable_event_sources(Connection *c) {
        uint32_t a = 0, b = 0;
        int r;

        assert(c);

        if (c->server_to_client_buffer_full > 0)
                b |= EPOLLOUT;
        if (c->server_to_client_buffer_full < c->server_to_client_buffer_size)
                a |= EPOLLIN;

        if (c->client_to_server_buffer_full > 0)
                a |= EPOLLOUT;
        if (c->client_to_server_buffer_full < c->client_to_server_buffer_size)
                b |= EPOLLIN;

        if (c->server_event_source)
                r = sd_event_source_set_io_events(c->server_event_source, a);
        else if (c->server_fd >= 0)
                r = sd_event_add_io(c->context->event, &c->server_event_source, c->server_fd, a, traffic_cb, c);
        else
                r = 0;

        if (r < 0)
                return log_error_errno(r, "Failed to set up server event source: %m");

        if (c->client_event_source)
                r = sd_event_source_set_io_events(c->client_event_source, b);
        else if (c->client_fd >= 0)
                r = sd_event_add_io(c->context->event, &c->client_event_source, c->client_fd, b, traffic_cb, c);
        else
                r = 0;

        if (r < 0)
                return log_error_errno(r, "Failed to set up client event source: %m");

        return 0;
}

int sd_icmp6_router_solicitation_start(sd_icmp6_nd *nd) {
        int r;

        assert(nd);
        assert(nd->event);

        if (nd->state != ICMP6_NEIGHBOR_DISCOVERY_IDLE)
                return -EINVAL;

        if (nd->index < 1)
                return -EINVAL;

        r = dhcp_network_icmp6_bind_router_solicitation(nd->index);
        if (r < 0)
                return r;

        nd->fd = r;

        r = sd_event_add_io(nd->event, &nd->recv, nd->fd, EPOLLIN,
                            icmp6_router_advertisment_recv, nd);
        if (r < 0)
                goto error;

        r = sd_event_source_set_priority(nd->recv, nd->event_priority);
        if (r < 0)
                goto error;

        r = sd_event_source_set_description(nd->recv, "icmp6-receive-message");
        if (r < 0)
                goto error;

        r = sd_event_add_time(nd->event, &nd->timeout, clock_boottime_or_monotonic(),
                              0, 0, icmp6_router_solicitation_timeout, nd);
        if (r < 0)
                goto error;

        r = sd_event_source_set_priority(nd->timeout, nd->event_priority);
        if (r < 0)
                goto error;

        r = sd_event_source_set_description(nd->timeout, "icmp6-timeout");
error:
        if (r < 0)
                icmp6_nd_init(nd);
        else
                log_icmp6_nd(client, "Start Router Solicitation");

        return r;
}

int server_open_dev_kmsg(Server *s) {
        int r;

        assert(s);

        s->dev_kmsg_fd = open("/dev/kmsg", O_RDWR|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
        if (s->dev_kmsg_fd < 0) {
                log_full(errno == ENOENT ? LOG_DEBUG : LOG_WARNING,
                         "Failed to open /dev/kmsg, ignoring: %m");
                return 0;
        }

        r = sd_event_add_io(s->event, &s->dev_kmsg_event_source, s->dev_kmsg_fd, EPOLLIN, dispatch_dev_kmsg, s);
        if (r < 0) {

                /* This will fail with EPERM on older kernels where
                 * /dev/kmsg is not readable. */
                if (r == -EPERM) {
                        r = 0;
                        goto fail;
                }

                log_error("Failed to add /dev/kmsg fd to event loop: %s", strerror(-r));
                goto fail;
        }

        r = sd_event_source_set_priority(s->dev_kmsg_event_source, SD_EVENT_PRIORITY_IMPORTANT+10);
        if (r < 0) {
                log_error("Failed to adjust priority of kmsg event source: %s", strerror(-r));
                goto fail;
        }

        s->dev_kmsg_readable = true;

        return 0;

fail:
        if (s->dev_kmsg_event_source)
                s->dev_kmsg_event_source = sd_event_source_unref(s->dev_kmsg_event_source);

        if (s->dev_kmsg_fd >= 0) {
                close_nointr_nofail(s->dev_kmsg_fd);
                s->dev_kmsg_fd = -1;
        }

        return r;
}