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.
11 years ago · 59ab90049f
parent afb9828d57
commit 59ab90049f
4 changed files with 434 additions and 0 deletions
--- a/configure.ac
+++ b/configure.ac
@ -379,6 +379,28 @@ if test "x$enable_colord" != "xno"; then
 fi
 AM_CONDITIONAL(ENABLE_COLORD, test "x$enable_colord" = "xyes")

+# dbus support
+AC_ARG_ENABLE(dbus,
+              AS_HELP_STRING([--disable-dbus],
+                             [do not build with dbus support]),,
+              enable_dbus=auto)
+if test "x$enable_dbus" != "xno"; then
+        PKG_CHECK_MODULES(DBUS,
+                          dbus-1 >= 1.6,
+                          have_dbus=yes,
+                          have_dbus=no)
+        if test "x$have_dbus" = "xno" -a "x$enable_dbus" = "xyes"; then
+                AC_MSG_ERROR([dbus support explicitly requested, but libdbus couldn't be found])
+        fi
+        if test "x$have_dbus" = "xyes"; then
+                enable_dbus=yes
+                AC_DEFINE([HAVE_DBUS], [1], [Build with dbus support])
+        else
+                enable_dbus=no
+        fi
+fi
+AM_CONDITIONAL(ENABLE_DBUS, test "x$enable_dbus" = "xyes")
+
 AC_ARG_ENABLE(wcap-tools, [  --disable-wcap-tools],, enable_wcap_tools=yes)
 AM_CONDITIONAL(BUILD_WCAP_TOOLS, test x$enable_wcap_tools = xyes)
 if test x$enable_wcap_tools = xyes; then
@ -467,6 +489,7 @@ AC_MSG_RESULT([
 	EGL				${enable_egl}
 	libxkbcommon			${enable_xkbcommon}
 	XWayland			${enable_xwayland}
+	dbus				${enable_dbus}

 	Build wcap utility		${enable_wcap_tools}
 	Build Tablet Shell		${enable_tablet_shell}
--- a/src/Makefile.am
+++ b/src/Makefile.am
@ -49,6 +49,14 @@ weston_SOURCES =				\
 	weston-launch.h				\
 	weston-egl-ext.h

+if ENABLE_DBUS
+weston_SOURCES +=				\
+	dbus.h					\
+	dbus.c
+weston_CFLAGS += $(DBUS_CFLAGS)
+weston_LDADD += $(DBUS_LIBS)
+endif
+
 git-version.h : .FORCE
 	$(AM_V_GEN)(echo "#define BUILD_ID \"$(shell git --git-dir=$(top_srcdir)/.git describe --always --dirty) $(shell git --git-dir=$(top_srcdir)/.git log -1 --format='%s (%ci)')\"" > $@-new; \
 	cmp -s $@ $@-new || cp $@-new $@; \
--- a/src/dbus.c
+++ 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);
+}
--- a/src/dbus.h
+++ b/src/dbus.h
@ -0,0 +1,67 @@
+/*
+ * 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.
+ */
+
+#ifndef _WESTON_DBUS_H_
+#define _WESTON_DBUS_H_
+
+#include "config.h"
+
+#include <errno.h>
+#include <wayland-server.h>
+
+#include "compositor.h"
+
+#ifdef HAVE_DBUS
+
+#include <dbus/dbus.h>
+
+/*
+ * weston_dbus_open() - Open new dbus connection
+ *
+ * Opens a new dbus connection to the bus given as @bus. It automatically
+ * integrates the new connection into the main-loop @loop. The connection
+ * itself is returned in @out.
+ * This also returns a context source used for dbus dispatching. It is
+ * returned on success in @ctx_out and must be passed to weston_dbus_close()
+ * unchanged. You must not access it from outside of a dbus helper!
+ *
+ * Returns 0 on success, negative error code on failure.
+ */
+int weston_dbus_open(struct wl_event_loop *loop, DBusBusType bus,
+		     DBusConnection **out, struct wl_event_source **ctx_out);
+
+/*
+ * weston_dbus_close() - Close dbus connection
+ *
+ * Closes a dbus connection that was previously opened via weston_dbus_open().
+ * It unbinds the connection from the main-loop it was previously bound to,
+ * closes the dbus connection and frees all resources. If you want to access
+ * @c after this call returns, you must hold a dbus-reference to it. But
+ * notice that the connection is closed after this returns so it cannot be
+ * used to spawn new dbus requests.
+ * You must pass the context source returns by weston_dbus_open() as @ctx.
+ */
+void weston_dbus_close(DBusConnection *c, struct wl_event_source *ctx);
+
+#endif /* HAVE_DBUS */
+
+#endif // _WESTON_DBUS_H_