Hotplug: Separate D-Bus into core and hotplug API components

Break up D-Bus into two components: a D-Bus core that can be used by any
part of the server (for the moment, just the D-Bus hotplug API, and the
forthcoming HAL hotplug API), and the old D-Bus hotplug API.

1 files changed, 233 insertions, 0 deletions

diff --git a/config/dbus-core.c b/config/dbus-core.c
new file mode 100644
index 000000000..b90e413f3
--- /dev/null
+++ b/config/dbus-core.c
@@ -0,0 +1,233 @@
+/*
+ * Copyright © 2006-2007 Daniel Stone
+ *
+ * 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 and/or authors
+ * not be used in advertising or publicity pertaining to distribution of the
+ * software without specific, written prior permission.  The copyright holders
+ * and/or authors 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 AND/OR AUTHORS DISCLAIM ALL WARRANTIES WITH REGARD
+ * TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS AND/OR AUTHORS 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.
+ */
+
+#ifdef HAVE_DIX_CONFIG_H
+#include <dix-config.h>
+#endif
+
+#define DBUS_API_SUBJECT_TO_CHANGE
+#include <dbus/dbus.h>
+#include <sys/select.h>
+
+#include "config-backends.h"
+#include "dix.h"
+#include "os.h"
+
+/* How often to attempt reconnecting when we get booted off the bus. */
+#define RECONNECT_DELAY (10 * 1000) /* in ms */
+
+struct dbus_core_info {
+    int fd;
+    DBusConnection *connection;
+    OsTimerPtr timer;
+    struct config_dbus_core_hook *hooks;
+};
+static struct dbus_core_info bus_info;
+
+static CARD32 reconnect_timer(OsTimerPtr timer, CARD32 time, pointer arg);
+
+static void
+wakeup_handler(pointer data, int err, pointer read_mask)
+{
+    struct dbus_core_info *info = data;
+
+    if (info->connection && FD_ISSET(info->fd, (fd_set *) read_mask))
+        dbus_connection_read_write_dispatch(info->connection, 0);
+}
+
+static void
+block_handler(pointer data, struct timeval **tv, pointer read_mask)
+{
+}
+
+/**
+ * Disconnect (if we haven't already been forcefully disconnected), clean up
+ * after ourselves, and call all registered disconnect hooks.
+ */
+static void
+teardown(void)
+{
+    struct config_dbus_core_hook *hook;
+
+    if (bus_info.timer) {
+        TimerCancel(bus_info.timer);
+        bus_info.timer = NULL;
+    }
+
+    /* We should really have pre-disconnect hooks and run them here, for
+     * completeness.  But then it gets awkward, given that you can't
+     * guarantee that they'll be called ... */
+    if (bus_info.connection)
+        dbus_connection_unref(bus_info.connection);
+
+    RemoveBlockAndWakeupHandlers(block_handler, wakeup_handler, &bus_info);
+    RemoveGeneralSocket(bus_info.fd);
+    bus_info.fd = -1;
+    bus_info.connection = NULL;
+
+    for (hook = bus_info.hooks; hook; hook = hook->next) {
+        if (hook->disconnect)
+            hook->disconnect(hook->data);
+    }
+}
+
+/**
+ * This is a filter, which only handles the disconnected signal, which
+ * doesn't go to the normal message handling function.  This takes
+ * precedence over the message handling function, so have have to be
+ * careful to ignore anything we don't want to deal with here.
+ */
+static DBusHandlerResult
+message_filter(DBusConnection *connection, DBusMessage *message, void *data)
+{
+    /* If we get disconnected, then take everything down, and attempt to
+     * reconnect immediately (assuming it's just a restart).  The
+     * connection isn't valid at this point, so throw it out immediately. */
+    if (dbus_message_is_signal(message, DBUS_INTERFACE_LOCAL,
+                                    "Disconnected")) {
+        DebugF("[config/dbus-core] disconnected from bus\n");
+        bus_info.connection = NULL;
+        teardown();
+
+        bus_info.timer = TimerSet(NULL, 0, 1, reconnect_timer, NULL);
+
+        return DBUS_HANDLER_RESULT_HANDLED;
+    }
+
+    return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
+}
+
+/**
+ * Attempt to connect to the system bus, and set a filter to deal with
+ * disconnection (see message_filter above).
+ *
+ * @return 1 on success, 0 on failure.
+ */
+static int
+connect_to_bus(void)
+{
+    DBusError error;
+    struct config_dbus_core_hook *hook;
+
+    dbus_error_init(&error);
+    bus_info.connection = dbus_bus_get(DBUS_BUS_SYSTEM, &error);
+    if (!bus_info.connection || dbus_error_is_set(&error)) {
+        DebugF("[config/dbus-core] error connecting to system bus: %s (%s)\n",
+               error.name, error.message);
+        goto err_begin;
+    }
+
+    /* Thankyou.  Really, thankyou. */
+    dbus_connection_set_exit_on_disconnect(bus_info.connection, FALSE);
+
+    if (!dbus_connection_get_unix_fd(bus_info.connection, &bus_info.fd)) {
+        ErrorF("[config/dbus-core] couldn't get fd for system bus\n");
+        goto err_unref;
+    }
+
+    if (!dbus_connection_add_filter(bus_info.connection, message_filter,
+                                    &bus_info, NULL)) {
+        ErrorF("[config/dbus-core] couldn't add filter: %s (%s)\n", error.name,
+               error.message);
+        goto err_fd;
+    }
+
+    dbus_error_free(&error);
+    AddGeneralSocket(bus_info.fd);
+
+    RegisterBlockAndWakeupHandlers(block_handler, wakeup_handler, &bus_info);
+
+    for (hook = bus_info.hooks; hook; hook = hook->next) {
+        if (hook->connect)
+            hook->connect(bus_info.connection, hook->data);
+    }
+
+    return 1;
+
+err_fd:
+    bus_info.fd = -1;
+err_unref:
+    dbus_connection_unref(bus_info.connection);
+    bus_info.connection = NULL;
+err_begin:
+    dbus_error_free(&error);
+
+    return 0;
+}
+
+static CARD32
+reconnect_timer(OsTimerPtr timer, CARD32 time, pointer arg)
+{
+    if (connect_to_bus()) {
+        bus_info.timer = NULL;
+        return 0;
+    }
+    else {
+        return RECONNECT_DELAY;
+    }
+}
+
+int
+config_dbus_core_add_hook(struct config_dbus_core_hook *hook)
+{
+    struct config_dbus_core_hook **prev;
+
+    for (prev = &bus_info.hooks; *prev; prev = &(*prev)->next)
+        ;
+    *prev = hook;
+
+    /* If we're already connected, call the connect hook. */
+    if (bus_info.connection)
+        hook->connect(bus_info.connection, hook->data);
+
+    return 1;
+}
+
+void
+config_dbus_core_remove_hook(struct config_dbus_core_hook *hook)
+{
+    struct config_dbus_core_hook **prev;
+
+    for (prev = &bus_info.hooks; *prev; prev = &(*prev)->next) {
+        if (*prev == hook)
+            *prev = hook->next;
+    }
+}
+
+int
+config_dbus_core_init(void)
+{
+    memset(&bus_info, 0, sizeof(bus_info));
+    bus_info.fd = -1;
+    bus_info.hooks = NULL;
+    bus_info.connection = NULL;
+    bus_info.timer = TimerSet(NULL, 0, 1, reconnect_timer, NULL);
+
+    return 1;
+}
+
+void
+config_dbus_core_fini(void)
+{
+    teardown();
+}