Add optional dbus helpers
This adds optional libdbus integration for weston. If libdbus is available
and not disabled via --disable-dbus during weston build, we now provide
basic DBusConnection main-loop integration for weston.
The dbus.c file provides a new helper to integrate any DBusConnection
object into a wl_event_loop object. This avoids any glib/qt/..
dependencies but instead only uses the low-level libdbus library.
Note that we do not provide dummy fallbacks for dbus helpers in case
dbus-support is disabled. The reason for that is that you need dbus/dbus.h
for nearly any operation you want to do via dbus. Therefore, only the most
basic helpers which can be used independently provide a "static inline"
dummy fallback to avoid #ifdef all over the code.
diff --git a/src/dbus.c b/src/dbus.c
new file mode 100644
index 0000000..4de8c9c
--- /dev/null
+++ b/src/dbus.c
@@ -0,0 +1,336 @@
+/*
+ * Copyright © 2013 David Herrmann <dh.herrmann@gmail.com>
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and
+ * its documentation for any purpose is hereby granted without fee, provided
+ * that the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation, and that the name of the copyright holders not be used in
+ * advertising or publicity pertaining to distribution of the software
+ * without specific, written prior permission. The copyright holders make
+ * no representations about the suitability of this software for any
+ * purpose. It is provided "as is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
+ * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
+ * CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * DBus Helpers
+ * This file contains the dbus mainloop integration and several helpers to
+ * make lowlevel libdbus access easier.
+ */
+
+#include "config.h"
+
+#include <dbus/dbus.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/epoll.h>
+#include <sys/eventfd.h>
+#include <sys/timerfd.h>
+#include <unistd.h>
+#include <wayland-server.h>
+
+#include "compositor.h"
+#include "dbus.h"
+
+/*
+ * DBus Mainloop Integration
+ * weston_dbus_bind() and weston_dbus_unbind() allow to bind an existing
+ * DBusConnection to an existing wl_event_loop object. All dbus dispatching
+ * is then nicely integrated into the wayland event loop.
+ * Note that this only provides basic watch and timeout dispatching. No
+ * remote thread wakeup, signal handling or other dbus insanity is supported.
+ * This is fine as long as you don't use any of the deprecated libdbus
+ * interfaces (like waking up remote threads..). There is really no rational
+ * reason to support these.
+ */
+
+static int weston_dbus_dispatch_watch(int fd, uint32_t mask, void *data)
+{
+ DBusWatch *watch = data;
+ uint32_t flags = 0;
+
+ if (dbus_watch_get_enabled(watch)) {
+ if (mask & WL_EVENT_READABLE)
+ flags |= DBUS_WATCH_READABLE;
+ if (mask & WL_EVENT_WRITABLE)
+ flags |= DBUS_WATCH_WRITABLE;
+ if (mask & WL_EVENT_HANGUP)
+ flags |= DBUS_WATCH_HANGUP;
+ if (mask & WL_EVENT_ERROR)
+ flags |= DBUS_WATCH_ERROR;
+
+ dbus_watch_handle(watch, flags);
+ }
+
+ return 0;
+}
+
+static dbus_bool_t weston_dbus_add_watch(DBusWatch *watch, void *data)
+{
+ struct wl_event_loop *loop = data;
+ struct wl_event_source *s;
+ int fd;
+ uint32_t mask = 0, flags;
+
+ if (dbus_watch_get_enabled(watch)) {
+ flags = dbus_watch_get_flags(watch);
+ if (flags & DBUS_WATCH_READABLE)
+ mask |= WL_EVENT_READABLE;
+ if (flags & DBUS_WATCH_WRITABLE)
+ mask |= WL_EVENT_WRITABLE;
+ }
+
+ fd = dbus_watch_get_unix_fd(watch);
+ s = wl_event_loop_add_fd(loop, fd, mask, weston_dbus_dispatch_watch,
+ watch);
+ if (!s)
+ return FALSE;
+
+ dbus_watch_set_data(watch, s, NULL);
+ return TRUE;
+}
+
+static void weston_dbus_remove_watch(DBusWatch *watch, void *data)
+{
+ struct wl_event_source *s;
+
+ s = dbus_watch_get_data(watch);
+ if (!s)
+ return;
+
+ wl_event_source_remove(s);
+}
+
+static void weston_dbus_toggle_watch(DBusWatch *watch, void *data)
+{
+ struct wl_event_source *s;
+ uint32_t mask = 0, flags;
+
+ s = dbus_watch_get_data(watch);
+ if (!s)
+ return;
+
+ if (dbus_watch_get_enabled(watch)) {
+ flags = dbus_watch_get_flags(watch);
+ if (flags & DBUS_WATCH_READABLE)
+ mask |= WL_EVENT_READABLE;
+ if (flags & DBUS_WATCH_WRITABLE)
+ mask |= WL_EVENT_WRITABLE;
+ }
+
+ wl_event_source_fd_update(s, mask);
+}
+
+static int weston_dbus_dispatch_timeout(void *data)
+{
+ DBusTimeout *timeout = data;
+
+ if (dbus_timeout_get_enabled(timeout))
+ dbus_timeout_handle(timeout);
+
+ return 0;
+}
+
+static int weston_dbus_adjust_timeout(DBusTimeout *timeout,
+ struct wl_event_source *s)
+{
+ int64_t t = 0;
+
+ if (dbus_timeout_get_enabled(timeout))
+ t = dbus_timeout_get_interval(timeout);
+
+ return wl_event_source_timer_update(s, t);
+}
+
+static dbus_bool_t weston_dbus_add_timeout(DBusTimeout *timeout, void *data)
+{
+ struct wl_event_loop *loop = data;
+ struct wl_event_source *s;
+ int r;
+
+ s = wl_event_loop_add_timer(loop, weston_dbus_dispatch_timeout,
+ timeout);
+ if (!s)
+ return FALSE;
+
+ r = weston_dbus_adjust_timeout(timeout, s);
+ if (r < 0) {
+ wl_event_source_remove(s);
+ return FALSE;
+ }
+
+ dbus_timeout_set_data(timeout, s, NULL);
+ return TRUE;
+}
+
+static void weston_dbus_remove_timeout(DBusTimeout *timeout, void *data)
+{
+ struct wl_event_source *s;
+
+ s = dbus_timeout_get_data(timeout);
+ if (!s)
+ return;
+
+ wl_event_source_remove(s);
+}
+
+static void weston_dbus_toggle_timeout(DBusTimeout *timeout, void *data)
+{
+ struct wl_event_source *s;
+
+ s = dbus_timeout_get_data(timeout);
+ if (!s)
+ return;
+
+ weston_dbus_adjust_timeout(timeout, s);
+}
+
+static int weston_dbus_dispatch(int fd, uint32_t mask, void *data)
+{
+ DBusConnection *c = data;
+ int r;
+
+ do {
+ r = dbus_connection_dispatch(c);
+ if (r == DBUS_DISPATCH_COMPLETE)
+ r = 0;
+ else if (r == DBUS_DISPATCH_DATA_REMAINS)
+ r = -EAGAIN;
+ else if (r == DBUS_DISPATCH_NEED_MEMORY)
+ r = -ENOMEM;
+ else
+ r = -EIO;
+ } while (r == -EAGAIN);
+
+ if (r)
+ weston_log("cannot dispatch dbus events: %d\n", r);
+
+ return 0;
+}
+
+static int weston_dbus_bind(struct wl_event_loop *loop, DBusConnection *c,
+ struct wl_event_source **ctx_out)
+{
+ bool b;
+ int r, fd;
+
+ /* Idle events cannot reschedule themselves, therefore we use a dummy
+ * event-fd and mark it for post-dispatch. Hence, the dbus
+ * dispatcher is called after every dispatch-round.
+ * This is required as dbus doesn't allow dispatching events from
+ * within its own event sources. */
+ fd = eventfd(0, EFD_CLOEXEC);
+ if (fd < 0)
+ return -errno;
+
+ *ctx_out = wl_event_loop_add_fd(loop, fd, 0, weston_dbus_dispatch, c);
+ close(fd);
+
+ if (!*ctx_out)
+ return -ENOMEM;
+
+ wl_event_source_check(*ctx_out);
+
+ b = dbus_connection_set_watch_functions(c,
+ weston_dbus_add_watch,
+ weston_dbus_remove_watch,
+ weston_dbus_toggle_watch,
+ loop,
+ NULL);
+ if (!b) {
+ r = -ENOMEM;
+ goto error;
+ }
+
+ b = dbus_connection_set_timeout_functions(c,
+ weston_dbus_add_timeout,
+ weston_dbus_remove_timeout,
+ weston_dbus_toggle_timeout,
+ loop,
+ NULL);
+ if (!b) {
+ r = -ENOMEM;
+ goto error;
+ }
+
+ dbus_connection_ref(c);
+ return 0;
+
+error:
+ dbus_connection_set_timeout_functions(c, NULL, NULL, NULL,
+ NULL, NULL);
+ dbus_connection_set_watch_functions(c, NULL, NULL, NULL,
+ NULL, NULL);
+ wl_event_source_remove(*ctx_out);
+ *ctx_out = NULL;
+ return r;
+}
+
+static void weston_dbus_unbind(DBusConnection *c, struct wl_event_source *ctx)
+{
+ dbus_connection_set_timeout_functions(c, NULL, NULL, NULL,
+ NULL, NULL);
+ dbus_connection_set_watch_functions(c, NULL, NULL, NULL,
+ NULL, NULL);
+ dbus_connection_unref(c);
+ wl_event_source_remove(ctx);
+}
+
+/*
+ * Convenience Helpers
+ * Several convenience helpers are provided to make using dbus in weston
+ * easier. We don't use any of the gdbus or qdbus helpers as they pull in
+ * huge dependencies and actually are quite awful to use. Instead, we only
+ * use the basic low-level libdbus library.
+ */
+
+int weston_dbus_open(struct wl_event_loop *loop, DBusBusType bus,
+ DBusConnection **out, struct wl_event_source **ctx_out)
+{
+ DBusConnection *c;
+ int r;
+
+ /* Ihhh, global state.. stupid dbus. */
+ dbus_connection_set_change_sigpipe(FALSE);
+
+ /* This is actually synchronous. It blocks for some authentication and
+ * setup. We just trust the dbus-server here and accept this blocking
+ * call. There is no real reason to complicate things further and make
+ * this asynchronous/non-blocking. A context should be created during
+ * thead/process/app setup, so blocking calls should be fine. */
+ c = dbus_bus_get_private(bus, NULL);
+ if (!c)
+ return -EIO;
+
+ dbus_connection_set_exit_on_disconnect(c, FALSE);
+
+ r = weston_dbus_bind(loop, c, ctx_out);
+ if (r < 0)
+ goto error;
+
+ *out = c;
+ return r;
+
+error:
+ dbus_connection_close(c);
+ dbus_connection_unref(c);
+ return r;
+}
+
+void weston_dbus_close(DBusConnection *c, struct wl_event_source *ctx)
+{
+ weston_dbus_unbind(c, ctx);
+ dbus_connection_close(c);
+ dbus_connection_unref(c);
+}