Feature #80: D-Bus support

- Add D-Bus support. Currently 7 methods are available: "reset" (same as
  SIGUSR1), "list_win" (list the windows compton manages), "win_get"
  (get a property of the window), "win_set" (set a property of the
  window), "find_win" (find window based on client window / focus),
  "opts_get" (get the value of a compton option), and "opts_set" (set
  the value of a compton option), together with 4 signals: "win_added",
  "win_destroyed", "win_mapped", "win_unmapped".

- D-Bus support depends on libdbus.

- As there are many items and my time is tight, no much tests are done.
  Bugs to be expected.

- Create a new header file `common.h` that contains shared content.

- Fix some bugs in timeout handling.

- Update file headers in all source files.

- Re-enable --unredir-if-possible on multi-screen set-ups, as the user
  could turn if off manually anyway.

- Check if the window is mapped in `repair_win()`.

- Add ps->track_atom_lst and its handlers, to prepare for the new
  condition format.

- Known issue 1: "win_get", "win_set", "opts_get", "opts_set" support a
  very limited number of targets only. New ones will be added gradually.

- Known issue 2: Accidental drop of D-Bus connection is not handled.

- Known issue 3: Introspection does not reveal all available methods,
  because some methods have unpredictable prototypes. Still hesitating
  about what to do...

- Known issue 4: Error handling is not finished yet. Compton does not
  always reply with the correct error message (but it does print out the
  correct error message, usually).

1 files changed, 920 insertions, 0 deletions

diff --git a/dbus.c b/dbus.c
new file mode 100644
index 000000000..16be7cc8f
--- /dev/null
+++ b/dbus.c
@@ -0,0 +1,920 @@
+/*
+ * Compton - a compositor for X11
+ *
+ * Based on `xcompmgr` - Copyright (c) 2003, Keith Packard
+ *
+ * Copyright (c) 2011-2013, Christopher Jeffrey
+ * See LICENSE for more information.
+ *
+ */
+
+#include "dbus.h"
+
+/**
+ * Initialize D-Bus connection.
+ */
+bool
+cdbus_init(session_t *ps) {
+  DBusError err = { };
+
+  // Initialize
+  dbus_error_init(&err);
+
+  // Connect to D-Bus
+  // Use dbus_bus_get_private() so we can fully recycle it ourselves
+  ps->dbus_conn = dbus_bus_get_private(DBUS_BUS_SESSION, &err);
+  if (dbus_error_is_set(&err)) {
+    printf_errf("(): D-Bus connection failed (%s).", err.message);
+    dbus_error_free(&err);
+    return false;
+  }
+
+  if (!ps->dbus_conn) {
+    printf_errf("(): D-Bus connection failed for unknown reason.");
+    return false;
+  }
+
+  // Avoid exiting on disconnect
+  dbus_connection_set_exit_on_disconnect(ps->dbus_conn, false);
+
+  // Request service name
+  {
+    // Get display name
+    char *display = DisplayString(ps->dpy);
+    if (!display)
+      display = "unknown";
+    display = mstrcpy(display);
+
+    // Convert all special characters in display name to underscore
+    {
+      char *pdisp = display;
+
+      while (*pdisp) {
+        if (!isalnum(*pdisp))
+          *pdisp = '_';
+        ++pdisp;
+      }
+    }
+
+    // Build service name
+    char *service = mstrjoin3(CDBUS_SERVICE_NAME, ".", display);
+    ps->dbus_service = service;
+
+    free(display);
+    display = NULL;
+
+    // Request for the name
+    int ret = dbus_bus_request_name(ps->dbus_conn, service,
+        DBUS_NAME_FLAG_DO_NOT_QUEUE, &err);
+
+    if (dbus_error_is_set(&err)) {
+      printf_errf("(): Failed to obtain D-Bus name (%s).", err.message);
+      dbus_error_free(&err);
+    }
+
+    if (DBUS_REQUEST_NAME_REPLY_PRIMARY_OWNER != ret
+        && DBUS_REQUEST_NAME_REPLY_ALREADY_OWNER != ret) {
+      printf_errf("(): Failed to become the primary owner of requested "
+          "D-Bus name (%d).", ret);
+    }
+  }
+
+
+  // Add watch handlers
+  if (!dbus_connection_set_watch_functions(ps->dbus_conn,
+        cdbus_callback_add_watch, cdbus_callback_remove_watch,
+        cdbus_callback_watch_toggled, ps, NULL)) {
+    printf_errf("(): Failed to add D-Bus watch functions.");
+    return false;
+  }
+
+  // Add timeout handlers
+  if (!dbus_connection_set_timeout_functions(ps->dbus_conn,
+        cdbus_callback_add_timeout, cdbus_callback_remove_timeout,
+        cdbus_callback_timeout_toggled, ps, NULL)) {
+    printf_errf("(): Failed to add D-Bus timeout functions.");
+    return false;
+  }
+
+  // Add match
+  dbus_bus_add_match(ps->dbus_conn,
+      "type='method_call',interface='" CDBUS_INTERFACE_NAME "'", &err);
+  if (dbus_error_is_set(&err)) {
+    printf_errf("(): Failed to add D-Bus match.");
+    dbus_error_free(&err);
+    return false;
+  }
+
+  return true;
+}
+
+/**
+ * Destroy D-Bus connection.
+ */
+void
+cdbus_destroy(session_t *ps) {
+  if (ps->dbus_conn) {
+    // Release DBus name firstly
+    if (ps->dbus_service) {
+      DBusError err = { };
+      dbus_error_init(&err);
+
+      dbus_bus_release_name(ps->dbus_conn, ps->dbus_service, &err);
+      if (dbus_error_is_set(&err)) {
+        printf_errf("(): Failed to release DBus name (%s).",
+            err.message);
+        dbus_error_free(&err);
+      }
+    }
+
+    // Close and unref the connection
+    dbus_connection_close(ps->dbus_conn);
+    dbus_connection_unref(ps->dbus_conn);
+  }
+}
+
+/** @name DBusTimeout handling
+ */
+///@{
+
+/**
+ * Callback for adding D-Bus timeout.
+ */
+static dbus_bool_t
+cdbus_callback_add_timeout(DBusTimeout *timeout, void *data) {
+  session_t *ps = data;
+
+  timeout_t *ptmout = timeout_insert(ps, dbus_timeout_get_interval(timeout),
+      cdbus_callback_handle_timeout, timeout);
+  if (ptmout)
+    dbus_timeout_set_data(timeout, ptmout, NULL);
+
+  return (bool) ptmout;
+}
+
+/**
+ * Callback for removing D-Bus timeout.
+ */
+static void
+cdbus_callback_remove_timeout(DBusTimeout *timeout, void *data) {
+  session_t *ps = data;
+
+  timeout_t *ptmout = dbus_timeout_get_data(timeout);
+  assert(ptmout);
+  if (ptmout)
+    timeout_drop(ps, ptmout);
+}
+
+/**
+ * Callback for toggling a D-Bus timeout.
+ */
+static void
+cdbus_callback_timeout_toggled(DBusTimeout *timeout, void *data) {
+  timeout_t *ptmout = dbus_timeout_get_data(timeout);
+
+  assert(ptmout);
+  if (ptmout) {
+    ptmout->enabled = dbus_timeout_get_enabled(timeout);
+    // Refresh interval as libdbus doc says: "Whenever a timeout is toggled,
+    // its interval may change."
+    ptmout->interval = dbus_timeout_get_interval(timeout);
+  }
+}
+
+/**
+ * Callback for handling a D-Bus timeout.
+ */
+static bool
+cdbus_callback_handle_timeout(session_t *ps, timeout_t *ptmout) {
+  assert(ptmout && ptmout->data);
+  if (ptmout && ptmout->data)
+    return dbus_timeout_handle(ptmout->data);
+
+  return false;
+}
+
+///@}
+
+/** @name DBusWatch handling
+ */
+///@{
+
+/**
+ * Callback for adding D-Bus watch.
+ */
+static dbus_bool_t
+cdbus_callback_add_watch(DBusWatch *watch, void *data) {
+  // Leave disabled watches alone
+  if (!dbus_watch_get_enabled(watch))
+    return TRUE;
+
+  session_t *ps = data;
+
+  // Insert the file descriptor
+  fds_insert(ps, dbus_watch_get_unix_fd(watch),
+      cdbus_get_watch_cond(watch));
+
+  // Always return true
+  return TRUE;
+}
+
+/**
+ * Callback for removing D-Bus watch.
+ */
+static void
+cdbus_callback_remove_watch(DBusWatch *watch, void *data) {
+  session_t *ps = data;
+
+  fds_drop(ps, dbus_watch_get_unix_fd(watch),
+      cdbus_get_watch_cond(watch));
+}
+
+/**
+ * Callback for toggling D-Bus watch status.
+ */
+static void
+cdbus_callback_watch_toggled(DBusWatch *watch, void *data) {
+  if (dbus_watch_get_enabled(watch)) {
+    cdbus_callback_add_watch(watch, data);
+  }
+  else {
+    cdbus_callback_remove_watch(watch, data);
+  }
+}
+
+///@}
+
+/** @name Message argument appending callbacks
+ */
+///@{
+
+/**
+ * Callback to append a bool argument to a message.
+ */
+static bool
+cdbus_apdarg_bool(session_t *ps, DBusMessage *msg, const void *data) {
+  assert(data);
+
+  dbus_bool_t val = *(const bool *) data;
+
+  if (!dbus_message_append_args(msg, DBUS_TYPE_BOOLEAN, &val,
+        DBUS_TYPE_INVALID)) {
+    printf_errf("(): Failed to append argument.");
+    return false;
+  }
+
+  return true;
+}
+
+/**
+ * Callback to append a Window argument to a message.
+ */
+static bool
+cdbus_apdarg_wid(session_t *ps, DBusMessage *msg, const void *data) {
+  assert(data);
+  cdbus_window_t val = *(const Window *)data;
+
+  if (!dbus_message_append_args(msg, CDBUS_TYPE_WINDOW, &val,
+        DBUS_TYPE_INVALID)) {
+    printf_errf("(): Failed to append argument.");
+    return false;
+  }
+
+  return true;
+}
+
+/**
+ * Callback to append an cdbus_enum_t argument to a message.
+ */
+static bool
+cdbus_apdarg_enum(session_t *ps, DBusMessage *msg, const void *data) {
+  assert(data);
+  if (!dbus_message_append_args(msg, CDBUS_TYPE_ENUM, data,
+        DBUS_TYPE_INVALID)) {
+    printf_errf("(): Failed to append argument.");
+    return false;
+  }
+
+  return true;
+}
+
+/**
+ * Callback to append a string argument to a message.
+ */
+static bool
+cdbus_apdarg_string(session_t *ps, DBusMessage *msg, const void *data) {
+  const char *str = data;
+  if (!str)
+    str = "";
+
+  if (!dbus_message_append_args(msg, DBUS_TYPE_STRING, &str,
+        DBUS_TYPE_INVALID)) {
+    printf_errf("(): Failed to append argument.");
+    return false;
+  }
+
+  return true;
+}
+
+/**
+ * Callback to append all window IDs to a message.
+ */
+static bool
+cdbus_apdarg_wids(session_t *ps, DBusMessage *msg, const void *data) {
+  // Get the number of wids we are to include
+  unsigned count = 0;
+  for (win *w = ps->list; w; w = w->next) {
+    if (!w->destroyed)
+      ++count;
+  }
+
+  // Allocate memory for an array of window IDs
+  cdbus_window_t *arr = malloc(sizeof(cdbus_window_t) * count);
+  if (!arr) {
+    printf_errf("(): Failed to allocate memory for window ID array.");
+    return false;
+  }
+
+  // Build the array
+  {
+    cdbus_window_t *pcur = arr;
+    for (win *w = ps->list; w; w = w->next) {
+      if (!w->destroyed) {
+        *pcur = w->id;
+        ++pcur;
+        assert(pcur <= arr + count);
+      }
+    }
+    assert(pcur == arr + count);
+  }
+
+  // Append arguments
+  if (!dbus_message_append_args(msg, DBUS_TYPE_ARRAY, CDBUS_TYPE_WINDOW,
+        &arr, count, DBUS_TYPE_INVALID)) {
+    printf_errf("(): Failed to append argument.");
+    free(arr);
+    return false;
+  }
+
+  free(arr);
+  return true;
+}
+///@}
+
+/**
+ * Send a D-Bus signal.
+ *
+ * @param ps current session
+ * @param name signal name
+ * @param func a function that modifies the built message, to, for example,
+ *        add an argument
+ * @param data data pointer to pass to the function
+ */
+static bool
+cdbus_signal(session_t *ps, const char *name,
+    bool (*func)(session_t *ps, DBusMessage *msg, const void *data),
+    const void *data) {
+  DBusMessage* msg = NULL;
+
+  // Create a signal
+  msg = dbus_message_new_signal(CDBUS_OBJECT_NAME, CDBUS_INTERFACE_NAME,
+      name);
+  if (!msg) {
+    printf_errf("(): Failed to create D-Bus signal.");
+    return false;
+  }
+
+  // Append arguments onto message
+  if (func && !func(ps, msg, data)) {
+    dbus_message_unref(msg);
+    return false;
+  }
+
+  // Send the message and flush the connection
+  if (!dbus_connection_send(ps->dbus_conn, msg, NULL)) {
+    printf_errf("(): Failed to send D-Bus signal.");
+    dbus_message_unref(msg);
+    return false;
+  }
+  dbus_connection_flush(ps->dbus_conn);
+
+  // Free the message
+  dbus_message_unref(msg);
+
+  return true;
+}
+
+/**
+ * Send a D-Bus reply.
+ *
+ * @param ps current session
+ * @param srcmsg original message
+ * @param func a function that modifies the built message, to, for example,
+ *        add an argument
+ * @param data data pointer to pass to the function
+ */
+static bool
+cdbus_reply(session_t *ps, DBusMessage *srcmsg,
+    bool (*func)(session_t *ps, DBusMessage *msg, const void *data),
+    const void *data) {
+  DBusMessage* msg = NULL;
+
+  // Create a reply
+  msg = dbus_message_new_method_return(srcmsg);
+  if (!msg) {
+    printf_errf("(): Failed to create D-Bus reply.");
+    return false;
+  }
+
+  // Append arguments onto message
+  if (func && !func(ps, msg, data)) {
+    dbus_message_unref(msg);
+    return false;
+  }
+
+  // Send the message and flush the connection
+  if (!dbus_connection_send(ps->dbus_conn, msg, NULL)) {
+    printf_errf("(): Failed to send D-Bus reply.");
+    dbus_message_unref(msg);
+    return false;
+  }
+  dbus_connection_flush(ps->dbus_conn);
+
+  // Free the message
+  dbus_message_unref(msg);
+
+  return true;
+}
+
+/**
+ * Send a D-Bus error reply.
+ *
+ * @param ps current session
+ * @param msg the new error DBusMessage
+ */
+static bool
+cdbus_reply_errm(session_t *ps, DBusMessage *msg) {
+  if (!msg) {
+    printf_errf("(): Failed to create D-Bus reply.");
+    return false;
+  }
+
+  // Send the message and flush the connection
+  if (!dbus_connection_send(ps->dbus_conn, msg, NULL)) {
+    printf_errf("(): Failed to send D-Bus reply.");
+    dbus_message_unref(msg);
+    return false;
+  }
+  dbus_connection_flush(ps->dbus_conn);
+
+  // Free the message
+  dbus_message_unref(msg);
+
+  return true;
+}
+
+/**
+ * Get n-th argument of a D-Bus message.
+ *
+ * @param count the position of the argument to get, starting from 0
+ * @param type libdbus type number of the type
+ * @param pdest pointer to the target
+ * @return true if successful, false otherwise.
+ */
+static bool
+cdbus_msg_get_arg(DBusMessage *msg, int count, const int type, void *pdest) {
+  assert(count >= 0);
+
+  DBusMessageIter iter = { };
+  if (!dbus_message_iter_init(msg, &iter)) {
+    printf_errf("(): Message has no argument.");
+    return false;
+  }
+
+  {
+    const int oldcount = count;
+    while (count) {
+      if (!dbus_message_iter_next(&iter)) {
+        printf_errf("(): Failed to find argument %d.", oldcount);
+        return false;
+      }
+      --count;
+    }
+  }
+
+  if (type != dbus_message_iter_get_arg_type(&iter)) {
+    printf_errf("(): Argument has incorrect type.");
+    return false;
+  }
+
+  dbus_message_iter_get_basic(&iter, pdest);
+
+  return true;
+}
+
+void
+cdbus_loop(session_t *ps) {
+  dbus_connection_read_write(ps->dbus_conn, 0);
+  DBusMessage *msg = NULL;
+  while ((msg = dbus_connection_pop_message(ps->dbus_conn)))
+    cdbus_process(ps, msg);
+}
+
+/** @name Message processing
+ */
+///@{
+
+/**
+ * Process a message from D-Bus.
+ */
+static void
+cdbus_process(session_t *ps, DBusMessage *msg) {
+  bool success = false;
+
+#define cdbus_m_ismethod(method) \
+  dbus_message_is_method_call(msg, CDBUS_INTERFACE_NAME, method)
+
+  if (cdbus_m_ismethod("reset")) {
+    ps->reset = true;
+    if (!dbus_message_get_no_reply(msg))
+      cdbus_reply_bool(ps, msg, true);
+    success = true;
+  }
+  else if (cdbus_m_ismethod("list_win")) {
+    success = cdbus_process_list_win(ps, msg);
+  }
+  else if (cdbus_m_ismethod("win_get")) {
+    success = cdbus_process_win_get(ps, msg);
+  }
+  else if (cdbus_m_ismethod("win_set")) {
+    success = cdbus_process_win_set(ps, msg);
+  }
+  else if (cdbus_m_ismethod("find_win")) {
+    success = cdbus_process_find_win(ps, msg);
+  }
+  else if (cdbus_m_ismethod("opts_get")) {
+    success = cdbus_process_opts_get(ps, msg);
+  }
+  else if (cdbus_m_ismethod("opts_set")) {
+    success = cdbus_process_opts_set(ps, msg);
+  }
+#undef cdbus_m_ismethod
+  else if (dbus_message_is_method_call(msg,
+        "org.freedesktop.DBus.Introspectable", "Introspect")) {
+    success = cdbus_process_introspect(ps, msg);
+  }
+  else if (dbus_message_is_signal(msg, "org.freedesktop.DBus", "NameAcquired")
+      || dbus_message_is_signal(msg, "org.freedesktop.DBus", "NameLost")) {
+    success = true;
+  }
+  else {
+    if (DBUS_MESSAGE_TYPE_ERROR == dbus_message_get_type(msg)) {
+      printf_errf("(): Error message of path \"%s\" "
+          "interface \"%s\", member \"%s\", error \"%s\"",
+          dbus_message_get_path(msg), dbus_message_get_interface(msg),
+          dbus_message_get_member(msg), dbus_message_get_error_name(msg));
+    }
+    else {
+      printf_errf("(): Illegal message of type \"%s\", path \"%s\" "
+          "interface \"%s\", member \"%s\"",
+          cdbus_repr_msgtype(msg), dbus_message_get_path(msg),
+          dbus_message_get_interface(msg), dbus_message_get_member(msg));
+    }
+    if (DBUS_MESSAGE_TYPE_METHOD_CALL == dbus_message_get_type(msg)
+        && !dbus_message_get_no_reply(msg))
+      cdbus_reply_err(ps, msg, CDBUS_ERROR_BADMSG, CDBUS_ERROR_BADMSG_S);
+    success = true;
+  }
+
+  // If the message could not be processed, and an reply is expected, return
+  // an empty reply.
+  if (!success && DBUS_MESSAGE_TYPE_METHOD_CALL == dbus_message_get_type(msg)
+      && !dbus_message_get_no_reply(msg))
+    cdbus_reply_err(ps, msg, CDBUS_ERROR_UNKNOWN, CDBUS_ERROR_UNKNOWN_S);
+
+  // Free the message
+  dbus_message_unref(msg);
+}
+
+/**
+ * Process a list_win D-Bus request.
+ */
+static bool
+cdbus_process_list_win(session_t *ps, DBusMessage *msg) {
+  cdbus_reply(ps, msg, cdbus_apdarg_wids, NULL);
+
+  return true;
+}
+
+/**
+ * Process a win_get D-Bus request.
+ */
+static bool
+cdbus_process_win_get(session_t *ps, DBusMessage *msg) {
+  cdbus_window_t wid = None;
+  const char *target = NULL;
+  DBusError err = { };
+
+  if (!dbus_message_get_args(msg, &err,
+        CDBUS_TYPE_WINDOW, &wid,
+        DBUS_TYPE_STRING, &target,
+        DBUS_TYPE_INVALID)) {
+    printf_errf("(): Failed to parse argument of \"win_get\" (%s).",
+        err.message);
+    dbus_error_free(&err);
+    return false;
+  }
+
+  win *w = find_win(ps, wid);
+
+  if (!w) {
+    printf_errf("(): Window %#010x not found.", wid);
+    cdbus_reply_err(ps, msg, CDBUS_ERROR_BADWIN, CDBUS_ERROR_BADWIN_S, wid);
+    return true;
+  }
+
+#define cdbus_m_win_get_do(tgt, apdarg_func) \
+  if (!strcmp(MSTR(tgt), target)) { \
+    apdarg_func(ps, msg, w->tgt); \
+    return true; \
+  }
+
+  cdbus_m_win_get_do(client_win, cdbus_reply_wid);
+  cdbus_m_win_get_do(damaged, cdbus_reply_bool);
+  cdbus_m_win_get_do(destroyed, cdbus_reply_bool);
+  cdbus_m_win_get_do(window_type, cdbus_reply_enum);
+  cdbus_m_win_get_do(wmwin, cdbus_reply_bool);
+  cdbus_m_win_get_do(leader, cdbus_reply_wid);
+  cdbus_m_win_get_do(focused_real, cdbus_reply_bool);
+  cdbus_m_win_get_do(shadow_force, cdbus_reply_enum);
+  cdbus_m_win_get_do(focused_force, cdbus_reply_enum);
+  cdbus_m_win_get_do(invert_color_force, cdbus_reply_enum);
+  if (!strcmp("map_state", target)) {
+    cdbus_reply_bool(ps, msg, w->a.map_state);
+    return true;
+  }
+#undef cdbus_m_win_get_do
+
+  printf_errf("(): No matching target found.");
+
+  return false;
+}
+
+/**
+ * Process a win_set D-Bus request.
+ */
+static bool
+cdbus_process_win_set(session_t *ps, DBusMessage *msg) {
+  cdbus_window_t wid = None;
+  const char *target = NULL;
+  DBusError err = { };
+
+  if (!dbus_message_get_args(msg, &err,
+        CDBUS_TYPE_WINDOW, &wid,
+        DBUS_TYPE_STRING, &target,
+        DBUS_TYPE_INVALID)) {
+    printf_errf("(): Failed to parse argument of \"win_set\" (%s).",
+        err.message);
+    dbus_error_free(&err);
+    return false;
+  }
+
+  win *w = find_win(ps, wid);
+
+  if (!w) {
+    printf_errf("(): Window %#010x not found.", wid);
+    cdbus_reply_err(ps, msg, CDBUS_ERROR_BADWIN, CDBUS_ERROR_BADWIN_S, wid);
+    return true;
+  }
+
+  ps->ev_received = true;
+
+#define cdbus_m_win_set_do(tgt, type, real_type) \
+  if (!strcmp(MSTR(tgt), target)) { \
+    real_type val; \
+    if (!cdbus_msg_get_arg(msg, 2, type, &val)) \
+      return false; \
+    w->tgt = val; \
+    goto cdbus_process_win_set_success; \
+  }
+
+  if (!strcmp("shadow_force", target)) {
+    cdbus_enum_t val = UNSET;
+    if (!cdbus_msg_get_arg(msg, 2, CDBUS_TYPE_ENUM, &val))
+      return false;
+    win_set_shadow_force(ps, w, val);
+    goto cdbus_process_win_set_success;
+  }
+
+  if (!strcmp("focused_force", target)) {
+    cdbus_enum_t val = UNSET;
+    if (!cdbus_msg_get_arg(msg, 2, CDBUS_TYPE_ENUM, &val))
+      return false;
+    win_set_focused_force(ps, w, val);
+    goto cdbus_process_win_set_success;
+  }
+
+  if (!strcmp("invert_color_force", target)) {
+    cdbus_enum_t val = UNSET;
+    if (!cdbus_msg_get_arg(msg, 2, CDBUS_TYPE_ENUM, &val))
+      return false;
+    win_set_invert_color_force(ps, w, val);
+    goto cdbus_process_win_set_success;
+  }
+#undef cdbus_m_win_set_do
+
+  printf_errf("(): No matching target found.");
+
+  return false;
+
+cdbus_process_win_set_success:
+  if (!dbus_message_get_no_reply(msg))
+    cdbus_reply_bool(ps, msg, true);
+  return true;
+}
+
+/**
+ * Process a find_win D-Bus request.
+ */
+static bool
+cdbus_process_find_win(session_t *ps, DBusMessage *msg) {
+  const char *target = NULL;
+
+  if (!cdbus_msg_get_arg(msg, 0, DBUS_TYPE_STRING, &target))
+    return false;
+
+  Window wid = None;
+
+  // Find window by client window
+  if (!strcmp("client", target)) {
+    cdbus_window_t client = None;
+    if (!cdbus_msg_get_arg(msg, 1, CDBUS_TYPE_WINDOW, &client))
+      return false;
+    win *w = find_toplevel(ps, client);
+    if (w)
+      wid = w->id;
+  }
+  // Find focused window
+  else if (!strcmp("focused", target)) {
+    win *w = find_focused(ps);
+    if (w)
+      wid = w->id;
+  }
+  else {
+    printf_errf("(): No matching target found.");
+
+    return false;
+  }
+
+  cdbus_reply_wid(ps, msg, wid);
+
+  return true;
+}
+
+/**
+ * Process a opts_get D-Bus request.
+ */
+static bool
+cdbus_process_opts_get(session_t *ps, DBusMessage *msg) {
+  const char *target = NULL;
+
+  if (!cdbus_msg_get_arg(msg, 0, DBUS_TYPE_STRING, &target))
+    return false;
+
+#define cdbus_m_opts_get_do(tgt, apdarg_func) \
+  if (!strcmp(MSTR(tgt), target)) { \
+    apdarg_func(ps, msg, ps->o.tgt); \
+    return true; \
+  }
+
+  cdbus_m_opts_get_do(display, cdbus_reply_string);
+  cdbus_m_opts_get_do(mark_wmwin_focused, cdbus_reply_bool);
+  cdbus_m_opts_get_do(mark_ovredir_focused, cdbus_reply_bool);
+  cdbus_m_opts_get_do(fork_after_register, cdbus_reply_bool);
+  cdbus_m_opts_get_do(detect_rounded_corners, cdbus_reply_bool);
+  cdbus_m_opts_get_do(paint_on_overlay, cdbus_reply_bool);
+  cdbus_m_opts_get_do(unredir_if_possible, cdbus_reply_bool);
+  cdbus_m_opts_get_do(logpath, cdbus_reply_string);
+  cdbus_m_opts_get_do(synchronize, cdbus_reply_bool);
+
+  cdbus_m_opts_get_do(clear_shadow, cdbus_reply_bool);
+#undef cdbus_m_opts_get_do
+
+  printf_errf("(): No matching target found.");
+
+  return false;
+}
+
+/**
+ * Process a opts_set D-Bus request.
+ */
+static bool
+cdbus_process_opts_set(session_t *ps, DBusMessage *msg) {
+  const char *target = NULL;
+
+  if (!cdbus_msg_get_arg(msg, 0, DBUS_TYPE_STRING, &target))
+    return false;
+
+#define cdbus_m_opts_set_do(tgt, type, real_type) \
+  if (!strcmp(MSTR(tgt), target)) { \
+    real_type val; \
+    if (!cdbus_msg_get_arg(msg, 1, type, &val)) \
+      return false; \
+    ps->o.tgt = val; \
+    goto cdbus_process_opts_set_success; \
+  }
+
+  // unredir_if_possible
+  if (!strcmp("unredir_if_possible", target)) {
+    dbus_bool_t val = FALSE;
+    if (!cdbus_msg_get_arg(msg, 1, DBUS_TYPE_BOOLEAN, &val))
+      return false;
+    if (ps->o.unredir_if_possible != val) {
+      ps->o.unredir_if_possible = val;
+      ps->ev_received = true;
+    }
+    goto cdbus_process_opts_set_success;
+  }
+
+  // clear_shadow
+  if (!strcmp("clear_shadow", target)) {
+    dbus_bool_t val = FALSE;
+    if (!cdbus_msg_get_arg(msg, 1, DBUS_TYPE_BOOLEAN, &val))
+      return false;
+    if (ps->o.clear_shadow != val) {
+      ps->o.clear_shadow = val;
+      force_repaint(ps);
+    }
+    goto cdbus_process_opts_set_success;
+  }
+#undef cdbus_m_opts_set_do
+
+  printf_errf("(): No matching target found.");
+
+  return false;
+
+cdbus_process_opts_set_success:
+  if (!dbus_message_get_no_reply(msg))
+    cdbus_reply_bool(ps, msg, true);
+  return true;
+}
+
+/**
+ * Process an Introspect D-Bus request.
+ */
+static bool
+cdbus_process_introspect(session_t *ps, DBusMessage *msg) {
+  const static char *str_introspect =
+    "<!DOCTYPE node PUBLIC \"-//freedesktop//DTD D-BUS Object Introspection 1.0//EN\"\n"
+    " \"http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd\">\n"
+    "<node name='" CDBUS_OBJECT_NAME "'>\n"
+    "  <interface name='" CDBUS_INTERFACE_NAME "'>\n"
+    "    <signal name='win_added'>\n"
+    "      <arg name='wid' type='" CDBUS_TYPE_WINDOW_STR "'/>\n"
+    "    </signal>\n"
+    "    <signal name='win_destroyed'>\n"
+    "      <arg name='wid' type='" CDBUS_TYPE_WINDOW_STR "'/>\n"
+    "    </signal>\n"
+    "    <signal name='win_mapped'>\n"
+    "      <arg name='wid' type='" CDBUS_TYPE_WINDOW_STR "'/>\n"
+    "    </signal>\n"
+    "    <signal name='win_unmapped'>\n"
+    "      <arg name='wid' type='" CDBUS_TYPE_WINDOW_STR "'/>\n"
+    "    </signal>\n"
+    "    <method name='reset' />\n"
+    "  </interface>\n"
+    "</node>\n";
+
+  cdbus_reply_string(ps, msg, str_introspect);
+
+  return true;
+}
+///@}
+
+/** @name Core callbacks
+ */
+///@{
+void
+cdbus_ev_win_added(session_t *ps, win *w) {
+  if (ps->dbus_conn)
+    cdbus_signal_wid(ps, "win_added", w->id);
+}
+
+void
+cdbus_ev_win_destroyed(session_t *ps, win *w) {
+  if (ps->dbus_conn)
+    cdbus_signal_wid(ps, "win_destroyed", w->id);
+}
+
+void
+cdbus_ev_win_mapped(session_t *ps, win *w) {
+  if (ps->dbus_conn)
+    cdbus_signal_wid(ps, "win_mapped", w->id);
+}
+
+void
+cdbus_ev_win_unmapped(session_t *ps, win *w) {
+  if (ps->dbus_conn)
+    cdbus_signal_wid(ps, "win_unmapped", w->id);
+}
+//!@}