bus/at-spi-bus-launcher.c

   1 /* -*- mode: c; c-basic-offset: 2; indent-tabs-mode: nil; -*-
   2  *
   3  * at-spi-bus-launcher: Manage the a11y bus as a child process
   4  *
   5  * Copyright 2011 Red Hat, Inc.
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Library General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2 of the License, or (at your option) any later version.
  11  *
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Library General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Library General Public
  18  * License along with this library; if not, write to the
  19  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  20  * Boston, MA 02111-1307, USA.
  21  */
  22
  23 #include "config.h"
  24
  25 #include <unistd.h>
  26 #include <string.h>
  27 #include <signal.h>
  28 #include <sys/wait.h>
  29 #include <errno.h>
  30 #include <stdio.h>
  31
  32 #include <gio/gio.h>
  33 #ifdef HAVE_X11
  34 #include <X11/Xlib.h>
  35 #include <X11/Xatom.h>
  36 #endif
  37
  38 typedef enum {
  39   A11Y_BUS_STATE_IDLE = 0,
  40   A11Y_BUS_STATE_READING_ADDRESS,
  41   A11Y_BUS_STATE_RUNNING,
  42   A11Y_BUS_STATE_ERROR
  43 } A11yBusState;
  44
  45 typedef struct {
  46   GMainLoop *loop;
  47   gboolean launch_immediately;
  48   gboolean a11y_enabled;
  49   gboolean screen_reader_enabled;
  50   GDBusConnection *session_bus;
  51   GSettings *a11y_schema;
  52   GSettings *interface_schema;
  53
  54   GDBusProxy *client_proxy;
  55
  56   A11yBusState state;
  57   /* -1 == error, 0 == pending, > 0 == running */
  58   int a11y_bus_pid;
  59   char *a11y_bus_address;
  60   int pipefd[2];
  61   char *a11y_launch_error_message;
  62 } A11yBusLauncher;
  63
  64 static A11yBusLauncher *_global_app = NULL;
  65
  66 static const gchar introspection_xml[] =
  67   "<node>"
  68   "  <interface name='org.a11y.Bus'>"
  69   "    <method name='GetAddress'>"
  70   "      <arg type='s' name='address' direction='out'/>"
  71   "    </method>"
  72   "  </interface>"
  73   "<interface name='org.a11y.Status'>"
  74   "<property name='IsEnabled' type='b' access='readwrite'/>"
  75   "<property name='ScreenReaderEnabled' type='b' access='readwrite'/>"
  76   "</interface>"
  77   "</node>";
  78 static GDBusNodeInfo *introspection_data = NULL;
  79
  80 static void
  81 respond_to_end_session (GDBusProxy *proxy)
  82 {
  83   GVariant *parameters;
  84
  85   parameters = g_variant_new ("(bs)", TRUE, "");
  86
  87   g_dbus_proxy_call (proxy,
  88                      "EndSessionResponse", parameters,
  89                      G_DBUS_CALL_FLAGS_NONE,
  90                      -1, NULL, NULL, NULL);
  91 }
  92
  93 static void
  94 g_signal_cb (GDBusProxy *proxy,
  95              gchar      *sender_name,
  96              gchar      *signal_name,
  97              GVariant   *parameters,
  98              gpointer    user_data)
  99 {
 100   A11yBusLauncher *app = user_data;
 101
 102   if (g_strcmp0 (signal_name, "QueryEndSession") == 0)
 103     respond_to_end_session (proxy);
 104   else if (g_strcmp0 (signal_name, "EndSession") == 0)
 105     respond_to_end_session (proxy);
 106   else if (g_strcmp0 (signal_name, "Stop") == 0)
 107     g_main_loop_quit (app->loop);
 108 }
 109
 110 static void
 111 client_proxy_ready_cb (GObject      *source_object,
 112                        GAsyncResult *res,
 113                        gpointer      user_data)
 114 {
 115   A11yBusLauncher *app = user_data;
 116   GError *error = NULL;
 117
 118   app->client_proxy = g_dbus_proxy_new_for_bus_finish (res, &error);
 119
 120   if (error != NULL)
 121     {
 122       g_warning ("Failed to get a client proxy: %s", error->message);
 123       g_error_free (error);
 124
 125       return;
 126     }
 127
 128   g_signal_connect (app->client_proxy, "g-signal",
 129                     G_CALLBACK (g_signal_cb), app);
 130 }
 131
 132 static void
 133 register_client (A11yBusLauncher *app)
 134 {
 135   GDBusProxyFlags flags;
 136   GDBusProxy *sm_proxy;
 137   GError *error;
 138   const gchar *app_id;
 139   const gchar *autostart_id;
 140   gchar *client_startup_id;
 141   GVariant *parameters;
 142   GVariant *variant;
 143   gchar *object_path;
 144
 145   flags = G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES |
 146           G_DBUS_PROXY_FLAGS_DO_NOT_CONNECT_SIGNALS;
 147
 148   error = NULL;
 149   sm_proxy = g_dbus_proxy_new_sync (app->session_bus, flags, NULL,
 150                                     "org.gnome.SessionManager",
 151                                     "/org/gnome/SessionManager",
 152                                     "org.gnome.SessionManager",
 153                                     NULL, &error);
 154
 155   if (error != NULL)
 156     {
 157       g_warning ("Failed to get session manager proxy: %s", error->message);
 158       g_error_free (error);
 159
 160       return;
 161     }
 162
 163   app_id = "at-spi-bus-launcher";
 164   autostart_id = g_getenv ("DESKTOP_AUTOSTART_ID");
 165
 166   if (autostart_id != NULL)
 167     {
 168       client_startup_id = g_strdup (autostart_id);
 169       g_unsetenv ("DESKTOP_AUTOSTART_ID");
 170     }
 171   else
 172     {
 173       client_startup_id = g_strdup ("");
 174     }
 175
 176   parameters = g_variant_new ("(ss)", app_id, client_startup_id);
 177   g_free (client_startup_id);
 178
 179   error = NULL;
 180   variant = g_dbus_proxy_call_sync (sm_proxy,
 181                                     "RegisterClient", parameters,
 182                                     G_DBUS_CALL_FLAGS_NONE,
 183                                     -1, NULL, &error);
 184
 185   g_object_unref (sm_proxy);
 186
 187   if (error != NULL)
 188     {
 189       g_warning ("Failed to register client: %s", error->message);
 190       g_error_free (error);
 191
 192       return;
 193     }
 194
 195   g_variant_get (variant, "(o)", &object_path);
 196   g_variant_unref (variant);
 197
 198   flags = G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES;
 199   g_dbus_proxy_new_for_bus (G_BUS_TYPE_SESSION, flags, NULL,
 200                             "org.gnome.SessionManager", object_path,
 201                             "org.gnome.SessionManager.ClientPrivate",
 202                             NULL, client_proxy_ready_cb, app);
 203
 204   g_free (object_path);
 205 }
 206
 207 static void
 208 setup_bus_child (gpointer data)
 209 {
 210   A11yBusLauncher *app = data;
 211   (void) app;
 212
 213   close (app->pipefd[0]);
 214   dup2 (app->pipefd[1], 3);
 215   close (app->pipefd[1]);
 216
 217   /* On Linux, tell the bus process to exit if this process goes away */
 218 #ifdef __linux
 219 #include <sys/prctl.h>
 220   prctl (PR_SET_PDEATHSIG, 15);
 221 #endif
 222 }
 223
 224 /**
 225  * unix_read_all_fd_to_string:
 226  *
 227  * Read all data from a file descriptor to a C string buffer.
 228  */
 229 static gboolean
 230 unix_read_all_fd_to_string (int      fd,
 231                             char    *buf,
 232                             ssize_t  max_bytes)
 233 {
 234   ssize_t bytes_read;
 235
 236   while (max_bytes > 1 && (bytes_read = read (fd, buf, MAX (4096, max_bytes - 1))))
 237     {
 238       if (bytes_read < 0)
 239         return FALSE;
 240       buf += bytes_read;
 241       max_bytes -= bytes_read;
 242     }
 243   *buf = '\0';
 244   return TRUE;
 245 }
 246
 247 static void
 248 on_bus_exited (GPid     pid,
 249                gint     status,
 250                gpointer data)
 251 {
 252   A11yBusLauncher *app = data;
 253
 254   app->a11y_bus_pid = -1;
 255   app->state = A11Y_BUS_STATE_ERROR;
 256   if (app->a11y_launch_error_message == NULL)
 257     {
 258       if (WIFEXITED (status))
 259         app->a11y_launch_error_message = g_strdup_printf ("Bus exited with code %d", WEXITSTATUS (status));
 260       else if (WIFSIGNALED (status))
 261         app->a11y_launch_error_message = g_strdup_printf ("Bus killed by signal %d", WTERMSIG (status));
 262       else if (WIFSTOPPED (status))
 263         app->a11y_launch_error_message = g_strdup_printf ("Bus stopped by signal %d", WSTOPSIG (status));
 264     }
 265   g_main_loop_quit (app->loop);
 266 }
 267
 268 static gboolean
 269 ensure_a11y_bus (A11yBusLauncher *app)
 270 {
 271   GPid pid;
 272   char *argv[] = { DBUS_DAEMON, NULL, "--nofork", "--print-address", "3", NULL };
 273   char addr_buf[2048];
 274   GError *error = NULL;
 275   const char *config_path = NULL;
 276
 277   if (app->a11y_bus_pid != 0)
 278     return FALSE;
 279
 280   if (g_file_test (SYSCONFDIR"/at-spi2/accessibility.conf", G_FILE_TEST_EXISTS))
 281       config_path = "--config-file="SYSCONFDIR"/at-spi2/accessibility.conf";
 282   else
 283       config_path = "--config-file="DATADIR"/defaults/at-spi2/accessibility.conf";
 284
 285   argv[1] = config_path;
 286
 287   if (pipe (app->pipefd) < 0)
 288     g_error ("Failed to create pipe: %s", strerror (errno));
 289
 290   if (!g_spawn_async (NULL,
 291                       argv,
 292                       NULL,
 293                       G_SPAWN_SEARCH_PATH | G_SPAWN_DO_NOT_REAP_CHILD,
 294                       setup_bus_child,
 295                       app,
 296                       &pid,
 297                       &error))
 298     {
 299       app->a11y_bus_pid = -1;
 300       app->a11y_launch_error_message = g_strdup (error->message);
 301       g_clear_error (&error);
 302       goto error;
 303     }
 304
 305   close (app->pipefd[1]);
 306   app->pipefd[1] = -1;
 307
 308   g_child_watch_add (pid, on_bus_exited, app);
 309
 310   app->state = A11Y_BUS_STATE_READING_ADDRESS;
 311   app->a11y_bus_pid = pid;
 312   g_debug ("Launched a11y bus, child is %ld", (long) pid);
 313   if (!unix_read_all_fd_to_string (app->pipefd[0], addr_buf, sizeof (addr_buf)))
 314     {
 315       app->a11y_launch_error_message = g_strdup_printf ("Failed to read address: %s", strerror (errno));
 316       kill (app->a11y_bus_pid, SIGTERM);
 317       goto error;
 318     }
 319   close (app->pipefd[0]);
 320   app->pipefd[0] = -1;
 321   app->state = A11Y_BUS_STATE_RUNNING;
 322
 323   /* Trim the trailing newline */
 324   app->a11y_bus_address = g_strchomp (g_strdup (addr_buf));
 325   g_debug ("a11y bus address: %s", app->a11y_bus_address);
 326
 327 #ifdef HAVE_X11
 328   {
 329     Display *display = XOpenDisplay (NULL);
 330     if (display)
 331       {
 332         Atom bus_address_atom = XInternAtom (display, "AT_SPI_BUS", False);
 333         XChangeProperty (display,
 334                          XDefaultRootWindow (display),
 335                          bus_address_atom,
 336                          XA_STRING, 8, PropModeReplace,
 337                          (guchar *) app->a11y_bus_address, strlen (app->a11y_bus_address));
 338         XFlush (display);
 339         XCloseDisplay (display);
 340       }
 341   }
 342 #endif
 343
 344   return TRUE;
 345
 346  error:
 347   close (app->pipefd[0]);
 348   close (app->pipefd[1]);
 349   app->state = A11Y_BUS_STATE_ERROR;
 350
 351   return FALSE;
 352 }
 353
 354 static void
 355 handle_method_call (GDBusConnection       *connection,
 356                     const gchar           *sender,
 357                     const gchar           *object_path,
 358                     const gchar           *interface_name,
 359                     const gchar           *method_name,
 360                     GVariant              *parameters,
 361                     GDBusMethodInvocation *invocation,
 362                     gpointer               user_data)
 363 {
 364   A11yBusLauncher *app = user_data;
 365
 366   if (g_strcmp0 (method_name, "GetAddress") == 0)
 367     {
 368       ensure_a11y_bus (app);
 369       if (app->a11y_bus_pid > 0)
 370         g_dbus_method_invocation_return_value (invocation,
 371                                                g_variant_new ("(s)", app->a11y_bus_address));
 372       else
 373         g_dbus_method_invocation_return_dbus_error (invocation,
 374                                                     "org.a11y.Bus.Error",
 375                                                     app->a11y_launch_error_message);
 376     }
 377 }
 378
 379 static GVariant *
 380 handle_get_property  (GDBusConnection       *connection,
 381                       const gchar           *sender,
 382                       const gchar           *object_path,
 383                       const gchar           *interface_name,
 384                       const gchar           *property_name,
 385                     GError **error,
 386                     gpointer               user_data)
 387 {
 388   A11yBusLauncher *app = user_data;
 389
 390   if (g_strcmp0 (property_name, "IsEnabled") == 0)
 391     return g_variant_new ("b", app->a11y_enabled);
 392   else if (g_strcmp0 (property_name, "ScreenReaderEnabled") == 0)
 393     return g_variant_new ("b", app->screen_reader_enabled);
 394   else
 395     return NULL;
 396 }
 397
 398 static void
 399 handle_a11y_enabled_change (A11yBusLauncher *app, gboolean enabled,
 400                                gboolean notify_gsettings)
 401 {
 402   GVariantBuilder builder;
 403   GVariantBuilder invalidated_builder;
 404
 405   if (enabled == app->a11y_enabled)
 406     return;
 407
 408   app->a11y_enabled = enabled;
 409
 410   if (notify_gsettings && app->interface_schema)
 411     {
 412       g_settings_set_boolean (app->interface_schema, "toolkit-accessibility",
 413                               enabled);
 414       g_settings_sync ();
 415     }
 416
 417   g_variant_builder_init (&builder, G_VARIANT_TYPE_ARRAY);
 418   g_variant_builder_init (&invalidated_builder, G_VARIANT_TYPE ("as"));
 419   g_variant_builder_add (&builder, "{sv}", "IsEnabled",
 420                          g_variant_new_boolean (enabled));
 421
 422   g_dbus_connection_emit_signal (app->session_bus, NULL, "/org/a11y/bus",
 423                                  "org.freedesktop.DBus.Properties",
 424                                  "PropertiesChanged",
 425                                  g_variant_new ("(sa{sv}as)", "org.a11y.Status",
 426                                                 &builder,
 427                                                 &invalidated_builder),
 428                                  NULL);
 429 }
 430
 431 static void
 432 handle_screen_reader_enabled_change (A11yBusLauncher *app, gboolean enabled,
 433                                gboolean notify_gsettings)
 434 {
 435   GVariantBuilder builder;
 436   GVariantBuilder invalidated_builder;
 437
 438   if (enabled == app->screen_reader_enabled)
 439     return;
 440
 441   /* If the screen reader is being enabled, we should enable accessibility
 442    * if it isn't enabled already */
 443   if (enabled)
 444     handle_a11y_enabled_change (app, enabled, notify_gsettings);
 445
 446   app->screen_reader_enabled = enabled;
 447
 448   if (notify_gsettings && app->a11y_schema)
 449     {
 450       g_settings_set_boolean (app->a11y_schema, "screen-reader-enabled",
 451                               enabled);
 452       g_settings_sync ();
 453     }
 454
 455   g_variant_builder_init (&builder, G_VARIANT_TYPE_ARRAY);
 456   g_variant_builder_init (&invalidated_builder, G_VARIANT_TYPE ("as"));
 457   g_variant_builder_add (&builder, "{sv}", "ScreenReaderEnabled",
 458                          g_variant_new_boolean (enabled));
 459
 460   g_dbus_connection_emit_signal (app->session_bus, NULL, "/org/a11y/bus",
 461                                  "org.freedesktop.DBus.Properties",
 462                                  "PropertiesChanged",
 463                                  g_variant_new ("(sa{sv}as)", "org.a11y.Status",
 464                                                 &builder,
 465                                                 &invalidated_builder),
 466                                  NULL);
 467 }
 468
 469 static gboolean
 470 handle_set_property  (GDBusConnection       *connection,
 471                       const gchar           *sender,
 472                       const gchar           *object_path,
 473                       const gchar           *interface_name,
 474                       const gchar           *property_name,
 475                       GVariant *value,
 476                     GError **error,
 477                     gpointer               user_data)
 478 {
 479   A11yBusLauncher *app = user_data;
 480   const gchar *type = g_variant_get_type_string (value);
 481   gboolean enabled;
 482
 483   if (g_strcmp0 (type, "b") != 0)
 484     {
 485       g_set_error (error, G_DBUS_ERROR, G_DBUS_ERROR_INVALID_ARGS,
 486                        "org.a11y.Status.%s expects a boolean but got %s", property_name, type);
 487       return FALSE;
 488     }
 489
 490   enabled = g_variant_get_boolean (value);
 491
 492   if (g_strcmp0 (property_name, "IsEnabled") == 0)
 493     {
 494       handle_a11y_enabled_change (app, enabled, TRUE);
 495       return TRUE;
 496     }
 497   else if (g_strcmp0 (property_name, "ScreenReaderEnabled") == 0)
 498     {
 499       handle_screen_reader_enabled_change (app, enabled, TRUE);
 500       return TRUE;
 501     }
 502   else
 503     {
 504       g_set_error (error, G_DBUS_ERROR, G_DBUS_ERROR_INVALID_ARGS,
 505                        "Unknown property '%s'", property_name);
 506       return FALSE;
 507     }
 508 }
 509
 510 static const GDBusInterfaceVTable bus_vtable =
 511 {
 512   handle_method_call,
 513   NULL, /* handle_get_property, */
 514   NULL  /* handle_set_property */
 515 };
 516
 517 static const GDBusInterfaceVTable status_vtable =
 518 {
 519   NULL, /* handle_method_call */
 520   handle_get_property,
 521   handle_set_property
 522 };
 523
 524 static void
 525 on_bus_acquired (GDBusConnection *connection,
 526                  const gchar     *name,
 527                  gpointer         user_data)
 528 {
 529   A11yBusLauncher *app = user_data;
 530   GError *error;
 531   guint registration_id;
 532
 533   if (connection == NULL)
 534     {
 535       g_main_loop_quit (app->loop);
 536       return;
 537     }
 538   app->session_bus = connection;
 539
 540   if (app->launch_immediately)
 541     {
 542       ensure_a11y_bus (app);
 543       if (app->state == A11Y_BUS_STATE_ERROR)
 544         {
 545           g_main_loop_quit (app->loop);
 546           return;
 547         }
 548     }
 549
 550   error = NULL;
 551   registration_id = g_dbus_connection_register_object (connection,
 552                                                        "/org/a11y/bus",
 553                                                        introspection_data->interfaces[0],
 554                                                        &bus_vtable,
 555                                                        _global_app,
 556                                                        NULL,
 557                                                        &error);
 558   if (registration_id == 0)
 559     {
 560       g_error ("%s", error->message);
 561       g_clear_error (&error);
 562     }
 563
 564   g_dbus_connection_register_object (connection,
 565                                      "/org/a11y/bus",
 566                                      introspection_data->interfaces[1],
 567                                      &status_vtable,
 568                                      _global_app,
 569                                      NULL,
 570                                      NULL);
 571 }
 572
 573 static void
 574 on_name_lost (GDBusConnection *connection,
 575               const gchar     *name,
 576               gpointer         user_data)
 577 {
 578   A11yBusLauncher *app = user_data;
 579   if (app->session_bus == NULL
 580       && connection == NULL
 581       && app->a11y_launch_error_message == NULL)
 582     app->a11y_launch_error_message = g_strdup ("Failed to connect to session bus");
 583   g_main_loop_quit (app->loop);
 584 }
 585
 586 static void
 587 on_name_acquired (GDBusConnection *connection,
 588                   const gchar     *name,
 589                   gpointer         user_data)
 590 {
 591   A11yBusLauncher *app = user_data;
 592
 593   register_client (app);
 594 }
 595
 596 static int sigterm_pipefd[2];
 597
 598 static void
 599 sigterm_handler (int signum)
 600 {
 601   write (sigterm_pipefd[1], "X", 1);
 602 }
 603
 604 static gboolean
 605 on_sigterm_pipe (GIOChannel  *channel,
 606                  GIOCondition condition,
 607                  gpointer     data)
 608 {
 609   A11yBusLauncher *app = data;
 610
 611   g_main_loop_quit (app->loop);
 612
 613   return FALSE;
 614 }
 615
 616 static void
 617 init_sigterm_handling (A11yBusLauncher *app)
 618 {
 619   GIOChannel *sigterm_channel;
 620
 621   if (pipe (sigterm_pipefd) < 0)
 622     g_error ("Failed to create pipe: %s", strerror (errno));
 623   signal (SIGTERM, sigterm_handler);
 624
 625   sigterm_channel = g_io_channel_unix_new (sigterm_pipefd[0]);
 626   g_io_add_watch (sigterm_channel,
 627                   G_IO_IN | G_IO_ERR | G_IO_HUP,
 628                   on_sigterm_pipe,
 629                   app);
 630 }
 631
 632 static gboolean
 633 already_running ()
 634 {
 635 #ifdef HAVE_X11
 636   Atom AT_SPI_BUS;
 637   Atom actual_type;
 638   Display *bridge_display;
 639   int actual_format;
 640   unsigned char *data = NULL;
 641   unsigned long nitems;
 642   unsigned long leftover;
 643   gboolean result = FALSE;
 644
 645   bridge_display = XOpenDisplay (NULL);
 646   if (!bridge_display)
 647               return FALSE;
 648
 649   AT_SPI_BUS = XInternAtom (bridge_display, "AT_SPI_BUS", False);
 650   XGetWindowProperty (bridge_display,
 651                       XDefaultRootWindow (bridge_display),
 652                       AT_SPI_BUS, 0L,
 653                       (long) BUFSIZ, False,
 654                       (Atom) 31, &actual_type, &actual_format,
 655                       &nitems, &leftover, &data);
 656
 657   if (data)
 658   {
 659     GDBusConnection *bus;
 660     bus = g_dbus_connection_new_for_address_sync ((const gchar *)data, 0,
 661                                                   NULL, NULL, NULL);
 662     if (bus != NULL)
 663       {
 664         result = TRUE;
 665         g_object_unref (bus);
 666       }
 667   }
 668
 669   XCloseDisplay (bridge_display);
 670   return result;
 671 #else
 672   return FALSE;
 673 #endif
 674 }
 675
 676 static GSettings *
 677 get_schema (const gchar *name)
 678 {
 679   const char * const *schemas = NULL;
 680   gint i;
 681
 682   schemas = g_settings_list_schemas ();
 683   for (i = 0; schemas[i]; i++)
 684   {
 685     if (!strcmp (schemas[i], name))
 686       return g_settings_new (schemas[i]);
 687   }
 688
 689   return NULL;
 690 }
 691
 692 static void
 693 gsettings_key_changed (GSettings *gsettings, const gchar *key, void *user_data)
 694 {
 695   gboolean new_val = g_settings_get_boolean (gsettings, key);
 696   A11yBusLauncher *app = user_data;
 697
 698   if (!strcmp (key, "toolkit-accessibility"))
 699     handle_a11y_enabled_change (_global_app, new_val, FALSE);
 700   else if (!strcmp (key, "screen-reader-enabled"))
 701     handle_screen_reader_enabled_change (_global_app, new_val, FALSE);
 702 }
 703
 704 int
 705 main (int    argc,
 706       char **argv)
 707 {
 708   GError *error = NULL;
 709   GMainLoop *loop;
 710   GDBusConnection *session_bus;
 711   int name_owner_id;
 712   gboolean a11y_set = FALSE;
 713   gboolean screen_reader_set = FALSE;
 714   gint i;
 715
 716   if (already_running ())
 717     return 0;
 718
 719   _global_app = g_slice_new0 (A11yBusLauncher);
 720   _global_app->loop = g_main_loop_new (NULL, FALSE);
 721
 722   for (i = 1; i < argc; i++)
 723     {
 724       if (!strcmp (argv[i], "--launch-immediately"))
 725         _global_app->launch_immediately = TRUE;
 726       else if (sscanf (argv[i], "--a11y=%d", &_global_app->a11y_enabled) == 1)
 727         a11y_set = TRUE;
 728       else if (sscanf (argv[i], "--screen-reader=%d",
 729                        &_global_app->screen_reader_enabled) == 1)
 730         screen_reader_set = TRUE;
 731     else
 732       g_error ("usage: %s [--launch-immediately] [--a11y=0|1] [--screen-reader=0|1]", argv[0]);
 733     }
 734
 735   _global_app->interface_schema = get_schema ("org.gnome.desktop.interface");
 736   _global_app->a11y_schema = get_schema ("org.gnome.desktop.a11y.applications");
 737
 738   if (!a11y_set)
 739     {
 740       _global_app->a11y_enabled = _global_app->interface_schema
 741                                   ? g_settings_get_boolean (_global_app->interface_schema, "toolkit-accessibility")
 742                                   : _global_app->launch_immediately;
 743     }
 744
 745   if (!screen_reader_set)
 746     {
 747       _global_app->screen_reader_enabled = _global_app->a11y_schema
 748                                   ? g_settings_get_boolean (_global_app->a11y_schema, "screen-reader-enabled")
 749                                   : FALSE;
 750     }
 751
 752   if (_global_app->interface_schema)
 753     g_signal_connect (_global_app->interface_schema,
 754                       "changed::toolkit-accessibility",
 755                       G_CALLBACK (gsettings_key_changed), _global_app);
 756
 757   if (_global_app->a11y_schema)
 758     g_signal_connect (_global_app->a11y_schema,
 759                       "changed::screen-reader-enabled",
 760                       G_CALLBACK (gsettings_key_changed), _global_app);
 761
 762   init_sigterm_handling (_global_app);
 763
 764   introspection_data = g_dbus_node_info_new_for_xml (introspection_xml, NULL);
 765   g_assert (introspection_data != NULL);
 766
 767   name_owner_id = g_bus_own_name (G_BUS_TYPE_SESSION,
 768                                   "org.a11y.Bus",
 769                                   G_BUS_NAME_OWNER_FLAGS_ALLOW_REPLACEMENT,
 770                                   on_bus_acquired,
 771                                   on_name_acquired,
 772                                   on_name_lost,
 773                                   _global_app,
 774                                   NULL);
 775
 776   g_main_loop_run (_global_app->loop);
 777
 778   if (_global_app->a11y_bus_pid > 0)
 779     kill (_global_app->a11y_bus_pid, SIGTERM);
 780
 781   /* Clear the X property if our bus is gone; in the case where e.g.
 782    * GDM is launching a login on an X server it was using before,
 783    * we don't want early login processes to pick up the stale address.
 784    */
 785 #ifdef HAVE_X11
 786   {
 787     Display *display = XOpenDisplay (NULL);
 788     if (display)
 789       {
 790         Atom bus_address_atom = XInternAtom (display, "AT_SPI_BUS", False);
 791         XDeleteProperty (display,
 792                          XDefaultRootWindow (display),
 793                          bus_address_atom);
 794
 795         XFlush (display);
 796         XCloseDisplay (display);
 797       }
 798   }
 799 #endif
 800
 801   if (_global_app->a11y_launch_error_message)
 802     {
 803       g_printerr ("Failed to launch bus: %s", _global_app->a11y_launch_error_message);
 804       return 1;
 805     }
 806   return 0;
 807 }