add basic (and not very useful) D-Bus support

1 files changed, 608 insertions, 0 deletions

diff --git a/dbus.c b/dbus.c
new file mode 100644
index 0000000000..17987210e6
--- /dev/null
+++ b/dbus.c
@@ -0,0 +1,608 @@
+/*-*- Mode: C; c-basic-offset: 8 -*-*/
+
+#include <dbus/dbus.h>
+
+#include <sys/epoll.h>
+#include <sys/timerfd.h>
+#include <errno.h>
+#include <unistd.h>
+
+#include "dbus.h"
+#include "log.h"
+#include "strv.h"
+
+static void bus_dispatch_status(DBusConnection *bus, DBusDispatchStatus status, void *data)  {
+        Manager *m = data;
+
+        assert(bus);
+        assert(m);
+
+        m->request_bus_dispatch = status != DBUS_DISPATCH_COMPLETE;
+}
+
+static uint32_t bus_flags_to_events(DBusWatch *bus_watch) {
+        unsigned flags;
+        uint32_t events = 0;
+
+        assert(bus_watch);
+
+        /* no watch flags for disabled watches */
+        if (!dbus_watch_get_enabled(bus_watch))
+                return 0;
+
+        flags = dbus_watch_get_flags(bus_watch);
+
+        if (flags & DBUS_WATCH_READABLE)
+                events |= EPOLLIN;
+        if (flags & DBUS_WATCH_WRITABLE)
+                events |= EPOLLOUT;
+
+        return events | EPOLLHUP | EPOLLERR;
+}
+
+static unsigned events_to_bus_flags(uint32_t events) {
+        unsigned flags = 0;
+
+        if (events & EPOLLIN)
+                flags |= DBUS_WATCH_READABLE;
+        if (events & EPOLLOUT)
+                flags |= DBUS_WATCH_WRITABLE;
+        if (events & EPOLLHUP)
+                flags |= DBUS_WATCH_HANGUP;
+        if (events & EPOLLERR)
+                flags |= DBUS_WATCH_ERROR;
+
+        return flags;
+}
+
+void bus_watch_event(Manager *m, Watch *w, int events) {
+        assert(m);
+        assert(w);
+
+        /* This is called by the event loop whenever there is
+         * something happening on D-Bus' file handles. */
+
+        if (!(dbus_watch_get_enabled(w->data.bus_watch)))
+                return;
+
+        dbus_watch_handle(w->data.bus_watch, events_to_bus_flags(events));
+}
+
+static dbus_bool_t bus_add_watch(DBusWatch *bus_watch, void *data) {
+        Manager *m = data;
+        Watch *w;
+        struct epoll_event ev;
+
+        assert(bus_watch);
+        assert(m);
+
+        if (!(w = new0(Watch, 1)))
+                return FALSE;
+
+        w->fd = dbus_watch_get_unix_fd(bus_watch);
+        w->type = WATCH_DBUS_WATCH;
+        w->data.bus_watch = bus_watch;
+
+        zero(ev);
+        ev.events = bus_flags_to_events(bus_watch);
+        ev.data.ptr = w;
+
+        if (epoll_ctl(m->epoll_fd, EPOLL_CTL_ADD, w->fd, &ev) < 0) {
+
+                if (errno != EEXIST) {
+                        free(w);
+                        return FALSE;
+                }
+
+                /* Hmm, bloody D-Bus creates multiple watches on the
+                 * same fd. epoll() does not like that. As a dirty
+                 * hack we simply dup() the fd and hence get a second
+                 * one we can safely add to the epoll(). */
+
+                if ((w->fd = dup(w->fd)) < 0) {
+                        free(w);
+                        return FALSE;
+                }
+
+                if (epoll_ctl(m->epoll_fd, EPOLL_CTL_ADD, w->fd, &ev) < 0) {
+                        free(w);
+                        close_nointr_nofail(w->fd);
+                        return FALSE;
+                }
+
+                w->fd_is_dupped = true;
+        }
+
+        dbus_watch_set_data(bus_watch, w, NULL);
+
+        return TRUE;
+}
+
+static void bus_remove_watch(DBusWatch *bus_watch, void *data) {
+        Manager *m = data;
+        Watch *w;
+
+        assert(bus_watch);
+        assert(m);
+
+        if (!(w = dbus_watch_get_data(bus_watch)))
+                return;
+
+        assert(w->type == WATCH_DBUS_WATCH);
+        assert_se(epoll_ctl(m->epoll_fd, EPOLL_CTL_DEL, w->fd, NULL) >= 0);
+
+        if (w->fd_is_dupped)
+                close_nointr_nofail(w->fd);
+
+        free(w);
+}
+
+static void bus_toggle_watch(DBusWatch *bus_watch, void *data) {
+        Manager *m = data;
+        Watch *w;
+        struct epoll_event ev;
+
+        assert(bus_watch);
+        assert(m);
+
+        assert_se(w = dbus_watch_get_data(bus_watch));
+        assert(w->type == WATCH_DBUS_WATCH);
+
+        zero(ev);
+        ev.events = bus_flags_to_events(bus_watch);
+        ev.data.ptr = w;
+
+        assert_se(epoll_ctl(m->epoll_fd, EPOLL_CTL_MOD, w->fd, &ev) == 0);
+}
+
+static int bus_timeout_arm(Manager *m, Watch *w) {
+        struct itimerspec its;
+
+        assert(m);
+        assert(w);
+
+        zero(its);
+
+        if (dbus_timeout_get_enabled(w->data.bus_timeout)) {
+                timespec_store(&its.it_value, dbus_timeout_get_interval(w->data.bus_timeout) * USEC_PER_MSEC);
+                its.it_interval = its.it_interval;
+        }
+
+        if (timerfd_settime(w->fd, 0, &its, NULL) < 0)
+                return -errno;
+
+        return 0;
+}
+
+void bus_timeout_event(Manager *m, Watch *w, int events) {
+        assert(m);
+        assert(w);
+
+        /* This is called by the event loop whenever there is
+         * something happening on D-Bus' file handles. */
+
+        if (!(dbus_timeout_get_enabled(w->data.bus_timeout)))
+                return;
+
+        dbus_timeout_handle(w->data.bus_timeout);
+}
+
+static dbus_bool_t bus_add_timeout(DBusTimeout *timeout, void *data) {
+        Manager *m = data;
+        Watch *w;
+        struct epoll_event ev;
+
+        assert(timeout);
+        assert(m);
+
+        if (!(w = new0(Watch, 1)))
+                return FALSE;
+
+        if (!(w->fd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK|TFD_CLOEXEC)) < 0)
+                goto fail;
+
+        w->type = WATCH_DBUS_TIMEOUT;
+        w->data.bus_timeout = timeout;
+
+        if (bus_timeout_arm(m, w) < 0)
+                goto fail;
+
+        zero(ev);
+        ev.events = EPOLLIN;
+        ev.data.ptr = w;
+
+        if (epoll_ctl(m->epoll_fd, EPOLL_CTL_ADD, w->fd, &ev) < 0)
+                goto fail;
+
+        dbus_timeout_set_data(timeout, w, NULL);
+
+        return TRUE;
+
+fail:
+        if (w->fd >= 0)
+                close_nointr_nofail(w->fd);
+
+        free(w);
+        return FALSE;
+}
+
+static void bus_remove_timeout(DBusTimeout *timeout, void *data) {
+        Manager *m = data;
+        Watch *w;
+
+        assert(timeout);
+        assert(m);
+
+        if (!(w = dbus_timeout_get_data(timeout)))
+                return;
+
+        assert(w->type == WATCH_DBUS_TIMEOUT);
+        assert_se(epoll_ctl(m->epoll_fd, EPOLL_CTL_DEL, w->fd, NULL) >= 0);
+        close_nointr_nofail(w->fd);
+        free(w);
+}
+
+static void bus_toggle_timeout(DBusTimeout *timeout, void *data) {
+        Manager *m = data;
+        Watch *w;
+        int r;
+
+        assert(timeout);
+        assert(m);
+
+        assert_se(w = dbus_timeout_get_data(timeout));
+        assert(w->type == WATCH_DBUS_TIMEOUT);
+
+        if ((r = bus_timeout_arm(m, w)) < 0)
+                log_error("Failed to rearm timer: %s", strerror(-r));
+}
+
+void bus_dispatch(Manager *m) {
+        assert(m);
+
+        if (dbus_connection_dispatch(m->bus) == DBUS_DISPATCH_COMPLETE)
+                m->request_bus_dispatch = false;
+}
+
+static int request_name(Manager *m) {
+        DBusMessage *message;
+        const char *name = "org.freedesktop.systemd1";
+        uint32_t flags = 0;
+
+        if (!(message = dbus_message_new_method_call(
+                              DBUS_SERVICE_DBUS,
+                              DBUS_PATH_DBUS,
+                              DBUS_INTERFACE_DBUS,
+                              "RequestName")))
+                return -ENOMEM;
+
+        if (!dbus_message_append_args(
+                            message,
+                            DBUS_TYPE_STRING, &name,
+                            DBUS_TYPE_UINT32, &flags,
+                            DBUS_TYPE_INVALID)) {
+                dbus_message_unref(message);
+                return -ENOMEM;
+        }
+
+        if (!dbus_connection_send(m->bus, message, NULL)) {
+                dbus_message_unref(message);
+                return -ENOMEM;
+        }
+
+        /* We simple ask for the name and don't wait for it. Sooner or
+         * later we'll have it, and we wouldn't know what to do on
+         * error anyway. */
+
+        dbus_message_unref(message);
+
+        return 0;
+}
+
+int bus_init(Manager *m) {
+        DBusError error;
+        char *id;
+        int r;
+
+        assert(m);
+
+        if (m->bus)
+                return 0;
+
+        dbus_connection_set_change_sigpipe(FALSE);
+
+        dbus_error_init(&error);
+        if (!(m->bus = dbus_bus_get_private(m->is_init ? DBUS_BUS_SYSTEM : DBUS_BUS_SESSION, &error))) {
+                log_error("Failed to get D-Bus connection: %s", error.message);
+                dbus_error_free(&error);
+                return -ECONNREFUSED;
+        }
+
+        dbus_connection_set_exit_on_disconnect(m->bus, FALSE);
+        dbus_connection_set_dispatch_status_function(m->bus, bus_dispatch_status, m, NULL);
+        if (!dbus_connection_set_watch_functions(m->bus, bus_add_watch, bus_remove_watch, bus_toggle_watch, m, NULL) ||
+            !dbus_connection_set_timeout_functions(m->bus, bus_add_timeout, bus_remove_timeout, bus_toggle_timeout, m, NULL) ||
+            !dbus_connection_register_object_path(m->bus, "/org/freedesktop/systemd1", &bus_manager_vtable, m) ||
+            !dbus_connection_register_fallback(m->bus, "/org/freedesktop/systemd1/unit", &bus_unit_vtable, m) ||
+            !dbus_connection_register_fallback(m->bus, "/org/freedesktop/systemd1/job", &bus_job_vtable, m)) {
+                bus_done(m);
+                return -ENOMEM;
+        }
+
+        if ((r = request_name(m)) < 0) {
+                bus_done(m);
+                return r;
+        }
+
+        log_debug("Successfully connected to D-Bus bus %s as %s",
+                  strnull((id = dbus_connection_get_server_id(m->bus))),
+                  strnull(dbus_bus_get_unique_name(m->bus)));
+        dbus_free(id);
+
+        m->request_bus_dispatch = true;
+
+        return 0;
+}
+
+void bus_done(Manager *m) {
+        assert(m);
+
+        if (m->bus) {
+                dbus_connection_close(m->bus);
+                dbus_connection_unref(m->bus);
+                m->bus = NULL;
+        }
+}
+
+DBusHandlerResult bus_default_message_handler(Manager *m, DBusMessage *message, const char*introspection, const BusProperty *properties) {
+        DBusError error;
+        DBusMessage *reply = NULL;
+        int r;
+
+        assert(m);
+        assert(message);
+
+        dbus_error_init(&error);
+
+        if (dbus_message_is_method_call(message, "org.freedesktop.DBus.Introspectable", "Introspect") && introspection) {
+
+                if (!(reply = dbus_message_new_method_return(message)))
+                        goto oom;
+
+                if (!dbus_message_append_args(reply, DBUS_TYPE_STRING, &introspection, DBUS_TYPE_INVALID))
+                        goto oom;
+
+        } else if (dbus_message_is_method_call(message, "org.freedesktop.DBus.Properties", "Get") && properties) {
+                const char *interface, *property;
+                const BusProperty *p;
+
+                if (!dbus_message_get_args(
+                            message,
+                            &error,
+                            DBUS_TYPE_STRING, &interface,
+                            DBUS_TYPE_STRING, &property,
+                            DBUS_TYPE_INVALID))
+                        return bus_send_error_reply(m, message, &error, -EINVAL);
+
+                for (p = properties; p->property; p++)
+                        if (streq(p->interface, interface) && streq(p->property, property))
+                                break;
+
+                if (p->property) {
+                        DBusMessageIter iter, sub;
+
+                        if (!(reply = dbus_message_new_method_return(message)))
+                                goto oom;
+
+                        dbus_message_iter_init_append(reply, &iter);
+
+                        if (!dbus_message_iter_open_container(&iter, DBUS_TYPE_VARIANT, p->signature, &sub))
+                                goto oom;
+
+                        if ((r = p->append(m, &sub, property, p->data)) < 0) {
+
+                                if (r == -ENOMEM)
+                                        goto oom;
+
+                                dbus_message_unref(reply);
+                                return bus_send_error_reply(m, message, NULL, r);
+                        }
+
+                        if (!dbus_message_iter_close_container(&iter, &sub))
+                                goto oom;
+                }
+        } else if (dbus_message_is_method_call(message, "org.freedesktop.DBus.Properties", "GetAll") && properties) {
+                const char *interface;
+                const BusProperty *p;
+                DBusMessageIter iter, sub, sub2, sub3;
+                bool any = false;
+
+                if (!dbus_message_get_args(
+                            message,
+                            &error,
+                            DBUS_TYPE_STRING, &interface,
+                            DBUS_TYPE_INVALID))
+                        return bus_send_error_reply(m, message, &error, -EINVAL);
+
+                if (!(reply = dbus_message_new_method_return(message)))
+                        goto oom;
+
+                dbus_message_iter_init_append(reply, &iter);
+
+                if (!dbus_message_iter_open_container(&iter, DBUS_TYPE_ARRAY, "{sv}", &sub))
+                        goto oom;
+
+                for (p = properties; p->property; p++) {
+                        if (!streq(p->interface, interface))
+                                continue;
+
+                        if (!dbus_message_iter_open_container(&sub, DBUS_TYPE_DICT_ENTRY, "sv" , &sub2) ||
+                            !dbus_message_iter_append_basic(&sub2, DBUS_TYPE_STRING, &p->property) ||
+                            !dbus_message_iter_open_container(&sub2, DBUS_TYPE_VARIANT, p->signature, &sub3))
+                                goto oom;
+
+                        if ((r = p->append(m, &sub3, p->property, p->data)) < 0) {
+
+                                if (r == -ENOMEM)
+                                        goto oom;
+
+                                dbus_message_unref(reply);
+                                return bus_send_error_reply(m, message, NULL, r);
+                        }
+
+                        if (!dbus_message_iter_close_container(&sub2, &sub3) ||
+                            !dbus_message_iter_close_container(&sub, &sub2))
+                                goto oom;
+
+                        any = true;
+                }
+
+                if (!dbus_message_iter_close_container(&iter, &sub))
+                        goto oom;
+        }
+
+        if (reply) {
+                if (!dbus_connection_send(m->bus, reply, NULL))
+                        goto oom;
+
+                dbus_message_unref(reply);
+                return DBUS_HANDLER_RESULT_HANDLED;
+        }
+
+        return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
+
+oom:
+        if (reply)
+                dbus_message_unref(reply);
+
+        dbus_error_free(&error);
+
+        return DBUS_HANDLER_RESULT_NEED_MEMORY;
+}
+
+
+
+static const char *error_to_dbus(int error) {
+
+        switch(error) {
+
+        case -EINVAL:
+                return DBUS_ERROR_INVALID_ARGS;
+
+        case -ENOMEM:
+                return DBUS_ERROR_NO_MEMORY;
+
+        case -EPERM:
+        case -EACCES:
+                return DBUS_ERROR_ACCESS_DENIED;
+
+        case -ESRCH:
+                return DBUS_ERROR_UNIX_PROCESS_ID_UNKNOWN;
+
+        case -ENOENT:
+                return DBUS_ERROR_FILE_NOT_FOUND;
+
+        case -EEXIST:
+                return DBUS_ERROR_FILE_EXISTS;
+
+        case -ETIMEDOUT:
+                return DBUS_ERROR_TIMEOUT;
+
+        case -EIO:
+                return DBUS_ERROR_IO_ERROR;
+
+        case -ENETRESET:
+        case -ECONNABORTED:
+        case -ECONNRESET:
+                return DBUS_ERROR_DISCONNECTED;
+        }
+
+        return DBUS_ERROR_FAILED;
+}
+
+DBusHandlerResult bus_send_error_reply(Manager *m, DBusMessage *message, DBusError *bus_error, int error) {
+        DBusMessage *reply = NULL;
+        const char *name, *text;
+
+        if (bus_error && dbus_error_is_set(bus_error)) {
+                name = bus_error->name;
+                text = bus_error->message;
+        } else {
+                name = error_to_dbus(error);
+                text = strerror(-error);
+        }
+
+        if (!(reply = dbus_message_new_error(message, name, text)))
+                goto oom;
+
+        if (!dbus_connection_send(m->bus, reply, NULL))
+                goto oom;
+
+        dbus_message_unref(reply);
+
+        if (bus_error)
+                dbus_error_free(bus_error);
+
+        return DBUS_HANDLER_RESULT_HANDLED;
+
+oom:
+        if (reply)
+                dbus_message_unref(reply);
+
+        if (bus_error)
+                dbus_error_free(bus_error);
+
+        return DBUS_HANDLER_RESULT_NEED_MEMORY;
+}
+
+int bus_property_append_string(Manager *m, DBusMessageIter *i, const char *property, void *data) {
+        const char *t = data;
+
+        assert(m);
+        assert(i);
+        assert(property);
+        assert(t);
+
+        if (!dbus_message_iter_append_basic(i, DBUS_TYPE_STRING, &t))
+                return -ENOMEM;
+
+        return 0;
+}
+
+int bus_property_append_strv(Manager *m, DBusMessageIter *i, const char *property, void *data) {
+        DBusMessageIter sub;
+        char **t = data;
+
+        assert(m);
+        assert(i);
+        assert(property);
+
+        if (!dbus_message_iter_open_container(i, DBUS_TYPE_ARRAY, "s", &sub))
+                return -ENOMEM;
+
+        STRV_FOREACH(t, t)
+                if (!dbus_message_iter_append_basic(&sub, DBUS_TYPE_STRING, t))
+                        return -ENOMEM;
+
+        if (!dbus_message_iter_close_container(i, &sub))
+                return -ENOMEM;
+
+        return 0;
+}
+
+int bus_property_append_bool(Manager *m, DBusMessageIter *i, const char *property, void *data) {
+        bool *b = data;
+        dbus_bool_t db;
+
+        assert(m);
+        assert(i);
+        assert(property);
+        assert(b);
+
+        db = *b;
+
+        if (!dbus_message_iter_append_basic(i, DBUS_TYPE_BOOLEAN, &db))
+                return -ENOMEM;
+
+        return 0;
+}