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 2011-2018 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 #ifdef __linux__
  29 #include <sys/prctl.h>
  30 #include <sys/socket.h>
  31 #include <sys/un.h>
  32 #endif
  33 #include <sys/wait.h>
  34 #include <errno.h>
  35 #include <stdio.h>
  36
  37 #include <gio/gio.h>
  38 #ifdef HAVE_X11
  39 #include <X11/Xlib.h>
  40 #include <X11/Xatom.h>
  41 #endif
  42
  43 typedef enum {
  44   A11Y_BUS_STATE_IDLE = 0,
  45   A11Y_BUS_STATE_READING_ADDRESS,
  46   A11Y_BUS_STATE_RUNNING,
  47   A11Y_BUS_STATE_ERROR
  48 } A11yBusState;
  49
  50 typedef struct {
  51   GMainLoop *loop;
  52   gboolean launch_immediately;
  53   gboolean a11y_enabled;
  54   gboolean screen_reader_enabled;
  55   GDBusConnection *session_bus;
  56   GSettings *a11y_schema;
  57   GSettings *interface_schema;
  58   int name_owner_id;
  59
  60   GDBusProxy *client_proxy;
  61
  62   A11yBusState state;
  63   /* -1 == error, 0 == pending, > 0 == running */
  64   int a11y_bus_pid;
  65   char *a11y_bus_address;
  66   int pipefd[2];
  67   int listenfd;
  68   char *a11y_launch_error_message;
  69 } A11yBusLauncher;
  70
  71 static A11yBusLauncher *_global_app = NULL;
  72
  73 static const gchar introspection_xml[] =
  74   "<node>"
  75   "  <interface name='org.a11y.Bus'>"
  76   "    <method name='GetAddress'>"
  77   "      <arg type='s' name='address' direction='out'/>"
  78   "    </method>"
  79   "  </interface>"
  80   "<interface name='org.a11y.Status'>"
  81   "<property name='IsEnabled' type='b' access='readwrite'/>"
  82   "<property name='ScreenReaderEnabled' type='b' access='readwrite'/>"
  83   "</interface>"
  84   "</node>";
  85 static GDBusNodeInfo *introspection_data = NULL;
  86
  87 static void
  88 respond_to_end_session (GDBusProxy *proxy)
  89 {
  90   GVariant *parameters;
  91
  92   parameters = g_variant_new ("(bs)", TRUE, "");
  93
  94   g_dbus_proxy_call (proxy,
  95                      "EndSessionResponse", parameters,
  96                      G_DBUS_CALL_FLAGS_NONE,
  97                      -1, NULL, NULL, NULL);
  98 }
  99
 100 static void
 101 g_signal_cb (GDBusProxy *proxy,
 102              gchar      *sender_name,
 103              gchar      *signal_name,
 104              GVariant   *parameters,
 105              gpointer    user_data)
 106 {
 107   A11yBusLauncher *app = user_data;
 108
 109   if (g_strcmp0 (signal_name, "QueryEndSession") == 0)
 110     respond_to_end_session (proxy);
 111   else if (g_strcmp0 (signal_name, "EndSession") == 0)
 112     respond_to_end_session (proxy);
 113   else if (g_strcmp0 (signal_name, "Stop") == 0)
 114     g_main_loop_quit (app->loop);
 115 }
 116
 117 static void
 118 client_proxy_ready_cb (GObject      *source_object,
 119                        GAsyncResult *res,
 120                        gpointer      user_data)
 121 {
 122   A11yBusLauncher *app = user_data;
 123   GError *error = NULL;
 124
 125   app->client_proxy = g_dbus_proxy_new_for_bus_finish (res, &error);
 126
 127   if (error != NULL)
 128     {
 129       g_warning ("Failed to get a client proxy: %s", error->message);
 130       g_error_free (error);
 131
 132       return;
 133     }
 134
 135   g_signal_connect (app->client_proxy, "g-signal",
 136                     G_CALLBACK (g_signal_cb), app);
 137 }
 138
 139 static void
 140 register_client (A11yBusLauncher *app)
 141 {
 142   GDBusProxyFlags flags;
 143   GDBusProxy *sm_proxy;
 144   GError *error;
 145   const gchar *app_id;
 146   const gchar *autostart_id;
 147   gchar *client_startup_id;
 148   GVariant *parameters;
 149   GVariant *variant;
 150   gchar *object_path;
 151
 152   flags = G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES |
 153           G_DBUS_PROXY_FLAGS_DO_NOT_CONNECT_SIGNALS;
 154
 155   error = NULL;
 156   sm_proxy = g_dbus_proxy_new_sync (app->session_bus, flags, NULL,
 157                                     "org.gnome.SessionManager",
 158                                     "/org/gnome/SessionManager",
 159                                     "org.gnome.SessionManager",
 160                                     NULL, &error);
 161
 162   if (error != NULL)
 163     {
 164       g_warning ("Failed to get session manager proxy: %s", error->message);
 165       g_error_free (error);
 166
 167       return;
 168     }
 169
 170   app_id = "at-spi-bus-launcher";
 171   autostart_id = g_getenv ("DESKTOP_AUTOSTART_ID");
 172
 173   if (autostart_id != NULL)
 174     {
 175       client_startup_id = g_strdup (autostart_id);
 176       g_unsetenv ("DESKTOP_AUTOSTART_ID");
 177     }
 178   else
 179     {
 180       client_startup_id = g_strdup ("");
 181     }
 182
 183   parameters = g_variant_new ("(ss)", app_id, client_startup_id);
 184   g_free (client_startup_id);
 185
 186   error = NULL;
 187   variant = g_dbus_proxy_call_sync (sm_proxy,
 188                                     "RegisterClient", parameters,
 189                                     G_DBUS_CALL_FLAGS_NONE,
 190                                     -1, NULL, &error);
 191
 192   g_object_unref (sm_proxy);
 193
 194   if (error != NULL)
 195     {
 196       g_warning ("Failed to register client: %s", error->message);
 197       g_error_free (error);
 198
 199       return;
 200     }
 201
 202   g_variant_get (variant, "(o)", &object_path);
 203   g_variant_unref (variant);
 204
 205   flags = G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES;
 206   g_dbus_proxy_new_for_bus (G_BUS_TYPE_SESSION, flags, NULL,
 207                             "org.gnome.SessionManager", object_path,
 208                             "org.gnome.SessionManager.ClientPrivate",
 209                             NULL, client_proxy_ready_cb, app);
 210
 211   g_free (object_path);
 212 }
 213
 214 static void
 215 name_appeared_handler (GDBusConnection *connection,
 216                        const gchar     *name,
 217                        const gchar     *name_owner,
 218                        gpointer         user_data)
 219 {
 220   A11yBusLauncher *app = user_data;
 221
 222   register_client (app);
 223 }
 224
 225 /**
 226  * unix_read_all_fd_to_string:
 227  *
 228  * Read all data from a file descriptor to a C string buffer.
 229  */
 230 static gboolean
 231 unix_read_all_fd_to_string (int      fd,
 232                             char    *buf,
 233                             ssize_t  max_bytes)
 234 {
 235   ssize_t bytes_read;
 236
 237   while (max_bytes > 1 && (bytes_read = read (fd, buf, MIN (4096, max_bytes - 1))))
 238     {
 239       if (bytes_read < 0)
 240         return FALSE;
 241       buf += bytes_read;
 242       max_bytes -= bytes_read;
 243     }
 244   *buf = '\0';
 245   return TRUE;
 246 }
 247
 248 static void
 249 on_bus_exited (GPid     pid,
 250                gint     status,
 251                gpointer data)
 252 {
 253   A11yBusLauncher *app = data;
 254
 255   app->a11y_bus_pid = -1;
 256   app->state = A11Y_BUS_STATE_ERROR;
 257   if (app->a11y_launch_error_message == NULL)
 258     {
 259       if (WIFEXITED (status))
 260         app->a11y_launch_error_message = g_strdup_printf ("Bus exited with code %d", WEXITSTATUS (status));
 261       else if (WIFSIGNALED (status))
 262         app->a11y_launch_error_message = g_strdup_printf ("Bus killed by signal %d", WTERMSIG (status));
 263       else if (WIFSTOPPED (status))
 264         app->a11y_launch_error_message = g_strdup_printf ("Bus stopped by signal %d", WSTOPSIG (status));
 265     }
 266   g_main_loop_quit (app->loop);
 267 }
 268
 269 #ifdef DBUS_DAEMON
 270 static void
 271 setup_bus_child_daemon (gpointer data)
 272 {
 273   A11yBusLauncher *app = data;
 274   (void) app;
 275
 276   close (app->pipefd[0]);
 277   dup2 (app->pipefd[1], 3);
 278   close (app->pipefd[1]);
 279
 280   /* On Linux, tell the bus process to exit if this process goes away */
 281 #ifdef __linux__
 282   prctl (PR_SET_PDEATHSIG, 15);
 283 #endif
 284 }
 285
 286 static gboolean
 287 ensure_a11y_bus_daemon (A11yBusLauncher *app, char *config_path)
 288 {
 289   char *argv[] = { DBUS_DAEMON, config_path, "--nofork", "--print-address", "3", NULL };
 290   GPid pid;
 291   char addr_buf[2048];
 292   GError *error = NULL;
 293
 294   if (pipe (app->pipefd) < 0)
 295     g_error ("Failed to create pipe: %s", strerror (errno));
 296
 297   g_clear_pointer (&app->a11y_launch_error_message, g_free);
 298
 299   if (!g_spawn_async (NULL,
 300                       argv,
 301                       NULL,
 302                       G_SPAWN_SEARCH_PATH | G_SPAWN_DO_NOT_REAP_CHILD,
 303                       setup_bus_child_daemon,
 304                       app,
 305                       &pid,
 306                       &error))
 307     {
 308       app->a11y_bus_pid = -1;
 309       app->a11y_launch_error_message = g_strdup (error->message);
 310       g_clear_error (&error);
 311       goto error;
 312     }
 313
 314   close (app->pipefd[1]);
 315   app->pipefd[1] = -1;
 316
 317   g_child_watch_add (pid, on_bus_exited, app);
 318
 319   app->state = A11Y_BUS_STATE_READING_ADDRESS;
 320   app->a11y_bus_pid = pid;
 321   g_debug ("Launched a11y bus, child is %ld", (long) pid);
 322   if (!unix_read_all_fd_to_string (app->pipefd[0], addr_buf, sizeof (addr_buf)))
 323     {
 324       app->a11y_launch_error_message = g_strdup_printf ("Failed to read address: %s", strerror (errno));
 325       kill (app->a11y_bus_pid, SIGTERM);
 326       goto error;
 327     }
 328   close (app->pipefd[0]);
 329   app->pipefd[0] = -1;
 330   app->state = A11Y_BUS_STATE_RUNNING;
 331
 332   /* Trim the trailing newline */
 333   app->a11y_bus_address = g_strchomp (g_strdup (addr_buf));
 334   g_debug ("a11y bus address: %s", app->a11y_bus_address);
 335
 336   return TRUE;
 337
 338 error:
 339   close (app->pipefd[0]);
 340   close (app->pipefd[1]);
 341   app->state = A11Y_BUS_STATE_ERROR;
 342
 343   return FALSE;
 344 }
 345 #else
 346 static gboolean
 347 ensure_a11y_bus_daemon (A11yBusLauncher *app, char *config_path)
 348 {
 349         return FALSE;
 350 }
 351 #endif
 352
 353 #ifdef DBUS_BROKER
 354 static void
 355 setup_bus_child_broker (gpointer data)
 356 {
 357   A11yBusLauncher *app = data;
 358   gchar *pid_str;
 359   (void) app;
 360
 361   dup2 (app->listenfd, 3);
 362   close (app->listenfd);
 363   g_setenv("LISTEN_FDS", "1", TRUE);
 364
 365   pid_str = g_strdup_printf("%u", getpid());
 366   g_setenv("LISTEN_PID", pid_str, TRUE);
 367   g_free(pid_str);
 368
 369   /* Tell the bus process to exit if this process goes away */
 370   prctl (PR_SET_PDEATHSIG, SIGTERM);
 371 }
 372
 373 static gboolean
 374 ensure_a11y_bus_broker (A11yBusLauncher *app, char *config_path)
 375 {
 376   char *argv[] = { DBUS_BROKER, config_path, "--scope", "user", NULL };
 377   struct sockaddr_un addr = { .sun_family = AF_UNIX };
 378   socklen_t addr_len = sizeof(addr);
 379   GPid pid;
 380   GError *error = NULL;
 381
 382   if ((app->listenfd = socket (PF_UNIX, SOCK_STREAM | SOCK_NONBLOCK, 0)) < 0)
 383     g_error ("Failed to create listening socket: %s", strerror (errno));
 384
 385   if (bind (app->listenfd, (struct sockaddr *)&addr, sizeof(sa_family_t)) < 0)
 386     g_error ("Failed to bind listening socket: %s", strerror (errno));
 387
 388   if (getsockname (app->listenfd, (struct sockaddr *)&addr, &addr_len) < 0)
 389     g_error ("Failed to get socket name for listening socket: %s", strerror(errno));
 390
 391   if (listen (app->listenfd, 1024) < 0)
 392     g_error ("Failed to listen on socket: %s", strerror(errno));
 393
 394   g_clear_pointer (&app->a11y_launch_error_message, g_free);
 395
 396   if (!g_spawn_async (NULL,
 397                       argv,
 398                       NULL,
 399                       G_SPAWN_SEARCH_PATH | G_SPAWN_DO_NOT_REAP_CHILD,
 400                       setup_bus_child_broker,
 401                       app,
 402                       &pid,
 403                       &error))
 404     {
 405       app->a11y_bus_pid = -1;
 406       app->a11y_launch_error_message = g_strdup (error->message);
 407       g_clear_error (&error);
 408       goto error;
 409     }
 410
 411   close (app->listenfd);
 412   app->listenfd = -1;
 413
 414   g_child_watch_add (pid, on_bus_exited, app);
 415   app->a11y_bus_pid = pid;
 416   g_debug ("Launched a11y bus, child is %ld", (long) pid);
 417   app->state = A11Y_BUS_STATE_RUNNING;
 418
 419   app->a11y_bus_address = g_strconcat("unix:abstract=", addr.sun_path + 1, NULL);
 420   g_debug ("a11y bus address: %s", app->a11y_bus_address);
 421
 422   return TRUE;
 423
 424 error:
 425   close (app->listenfd);
 426   app->state = A11Y_BUS_STATE_ERROR;
 427
 428   return FALSE;
 429 }
 430 #else
 431 static gboolean
 432 ensure_a11y_bus_broker (A11yBusLauncher *app, char *config_path)
 433 {
 434         return FALSE;
 435 }
 436 #endif
 437
 438 static gboolean
 439 ensure_a11y_bus (A11yBusLauncher *app)
 440 {
 441   char *config_path = NULL;
 442   gboolean success = FALSE;
 443
 444   if (app->a11y_bus_pid != 0)
 445     return FALSE;
 446
 447   if (g_file_test (SYSCONFDIR"/at-spi2/accessibility.conf", G_FILE_TEST_EXISTS))
 448       config_path = "--config-file="SYSCONFDIR"/at-spi2/accessibility.conf";
 449   else
 450       config_path = "--config-file="DATADIR"/defaults/at-spi2/accessibility.conf";
 451
 452 #ifdef WANT_DBUS_BROKER
 453     success = ensure_a11y_bus_broker (app, config_path);
 454     if (!success)
 455       {
 456         if (!ensure_a11y_bus_daemon (app, config_path))
 457             return FALSE;
 458       }
 459 #else
 460     success = ensure_a11y_bus_daemon (app, config_path);
 461     if (!success)
 462       {
 463         if (!ensure_a11y_bus_broker (app, config_path))
 464             return FALSE;
 465       }
 466 #endif
 467
 468 #ifdef HAVE_X11
 469   {
 470     Display *display = XOpenDisplay (NULL);
 471     if (display)
 472       {
 473         Atom bus_address_atom = XInternAtom (display, "AT_SPI_BUS", False);
 474         XChangeProperty (display,
 475                          XDefaultRootWindow (display),
 476                          bus_address_atom,
 477                          XA_STRING, 8, PropModeReplace,
 478                          (guchar *) app->a11y_bus_address, strlen (app->a11y_bus_address));
 479         XFlush (display);
 480         XCloseDisplay (display);
 481       }
 482   }
 483 #endif
 484
 485   return TRUE;
 486 }
 487
 488 static void
 489 handle_method_call (GDBusConnection       *connection,
 490                     const gchar           *sender,
 491                     const gchar           *object_path,
 492                     const gchar           *interface_name,
 493                     const gchar           *method_name,
 494                     GVariant              *parameters,
 495                     GDBusMethodInvocation *invocation,
 496                     gpointer               user_data)
 497 {
 498   A11yBusLauncher *app = user_data;
 499
 500   if (g_strcmp0 (method_name, "GetAddress") == 0)
 501     {
 502       ensure_a11y_bus (app);
 503       if (app->a11y_bus_pid > 0)
 504         g_dbus_method_invocation_return_value (invocation,
 505                                                g_variant_new ("(s)", app->a11y_bus_address));
 506       else
 507         g_dbus_method_invocation_return_dbus_error (invocation,
 508                                                     "org.a11y.Bus.Error",
 509                                                     app->a11y_launch_error_message);
 510     }
 511 }
 512
 513 static GVariant *
 514 handle_get_property  (GDBusConnection       *connection,
 515                       const gchar           *sender,
 516                       const gchar           *object_path,
 517                       const gchar           *interface_name,
 518                       const gchar           *property_name,
 519                     GError **error,
 520                     gpointer               user_data)
 521 {
 522   A11yBusLauncher *app = user_data;
 523
 524   if (g_strcmp0 (property_name, "IsEnabled") == 0)
 525     return g_variant_new ("b", app->a11y_enabled);
 526   else if (g_strcmp0 (property_name, "ScreenReaderEnabled") == 0)
 527     return g_variant_new ("b", app->screen_reader_enabled);
 528   else
 529     return NULL;
 530 }
 531
 532 static void
 533 handle_a11y_enabled_change (A11yBusLauncher *app, gboolean enabled,
 534                                gboolean notify_gsettings)
 535 {
 536   GVariantBuilder builder;
 537   GVariantBuilder invalidated_builder;
 538
 539   if (enabled == app->a11y_enabled)
 540     return;
 541
 542   app->a11y_enabled = enabled;
 543
 544   if (notify_gsettings && app->interface_schema)
 545     {
 546       g_settings_set_boolean (app->interface_schema, "toolkit-accessibility",
 547                               enabled);
 548       g_settings_sync ();
 549     }
 550
 551   g_variant_builder_init (&builder, G_VARIANT_TYPE_ARRAY);
 552   g_variant_builder_init (&invalidated_builder, G_VARIANT_TYPE ("as"));
 553   g_variant_builder_add (&builder, "{sv}", "IsEnabled",
 554                          g_variant_new_boolean (enabled));
 555
 556   g_dbus_connection_emit_signal (app->session_bus, NULL, "/org/a11y/bus",
 557                                  "org.freedesktop.DBus.Properties",
 558                                  "PropertiesChanged",
 559                                  g_variant_new ("(sa{sv}as)", "org.a11y.Status",
 560                                                 &builder,
 561                                                 &invalidated_builder),
 562                                  NULL);
 563
 564   g_variant_builder_clear (&builder);
 565   g_variant_builder_clear (&invalidated_builder);
 566 }
 567
 568 static void
 569 handle_screen_reader_enabled_change (A11yBusLauncher *app, gboolean enabled,
 570                                gboolean notify_gsettings)
 571 {
 572   GVariantBuilder builder;
 573   GVariantBuilder invalidated_builder;
 574
 575   if (enabled == app->screen_reader_enabled)
 576     return;
 577
 578   /* If the screen reader is being enabled, we should enable accessibility
 579    * if it isn't enabled already */
 580   if (enabled)
 581     handle_a11y_enabled_change (app, enabled, notify_gsettings);
 582
 583   app->screen_reader_enabled = enabled;
 584
 585   if (notify_gsettings && app->a11y_schema)
 586     {
 587       g_settings_set_boolean (app->a11y_schema, "screen-reader-enabled",
 588                               enabled);
 589       g_settings_sync ();
 590     }
 591
 592   g_variant_builder_init (&builder, G_VARIANT_TYPE_ARRAY);
 593   g_variant_builder_init (&invalidated_builder, G_VARIANT_TYPE ("as"));
 594   g_variant_builder_add (&builder, "{sv}", "ScreenReaderEnabled",
 595                          g_variant_new_boolean (enabled));
 596
 597   g_dbus_connection_emit_signal (app->session_bus, NULL, "/org/a11y/bus",
 598                                  "org.freedesktop.DBus.Properties",
 599                                  "PropertiesChanged",
 600                                  g_variant_new ("(sa{sv}as)", "org.a11y.Status",
 601                                                 &builder,
 602                                                 &invalidated_builder),
 603                                  NULL);
 604
 605   g_variant_builder_clear (&builder);
 606   g_variant_builder_clear (&invalidated_builder);
 607 }
 608
 609 static gboolean
 610 handle_set_property  (GDBusConnection       *connection,
 611                       const gchar           *sender,
 612                       const gchar           *object_path,
 613                       const gchar           *interface_name,
 614                       const gchar           *property_name,
 615                       GVariant *value,
 616                     GError **error,
 617                     gpointer               user_data)
 618 {
 619   A11yBusLauncher *app = user_data;
 620   const gchar *type = g_variant_get_type_string (value);
 621   gboolean enabled;
 622
 623   if (g_strcmp0 (type, "b") != 0)
 624     {
 625       g_set_error (error, G_DBUS_ERROR, G_DBUS_ERROR_INVALID_ARGS,
 626                        "org.a11y.Status.%s expects a boolean but got %s", property_name, type);
 627       return FALSE;
 628     }
 629
 630   enabled = g_variant_get_boolean (value);
 631
 632   if (g_strcmp0 (property_name, "IsEnabled") == 0)
 633     {
 634       handle_a11y_enabled_change (app, enabled, TRUE);
 635       return TRUE;
 636     }
 637   else if (g_strcmp0 (property_name, "ScreenReaderEnabled") == 0)
 638     {
 639       handle_screen_reader_enabled_change (app, enabled, TRUE);
 640       return TRUE;
 641     }
 642   else
 643     {
 644       g_set_error (error, G_DBUS_ERROR, G_DBUS_ERROR_INVALID_ARGS,
 645                        "Unknown property '%s'", property_name);
 646       return FALSE;
 647     }
 648 }
 649
 650 static const GDBusInterfaceVTable bus_vtable =
 651 {
 652   handle_method_call,
 653   NULL, /* handle_get_property, */
 654   NULL  /* handle_set_property */
 655 };
 656
 657 static const GDBusInterfaceVTable status_vtable =
 658 {
 659   NULL, /* handle_method_call */
 660   handle_get_property,
 661   handle_set_property
 662 };
 663
 664 static void
 665 on_bus_acquired (GDBusConnection *connection,
 666                  const gchar     *name,
 667                  gpointer         user_data)
 668 {
 669   A11yBusLauncher *app = user_data;
 670   GError *error;
 671   guint registration_id;
 672
 673   if (connection == NULL)
 674     {
 675       g_main_loop_quit (app->loop);
 676       return;
 677     }
 678   app->session_bus = connection;
 679
 680   if (app->launch_immediately)
 681     {
 682       ensure_a11y_bus (app);
 683       if (app->state == A11Y_BUS_STATE_ERROR)
 684         {
 685           g_main_loop_quit (app->loop);
 686           return;
 687         }
 688     }
 689
 690   error = NULL;
 691   registration_id = g_dbus_connection_register_object (connection,
 692                                                        "/org/a11y/bus",
 693                                                        introspection_data->interfaces[0],
 694                                                        &bus_vtable,
 695                                                        _global_app,
 696                                                        NULL,
 697                                                        &error);
 698   if (registration_id == 0)
 699     {
 700       g_error ("%s", error->message);
 701       g_clear_error (&error);
 702     }
 703
 704   g_dbus_connection_register_object (connection,
 705                                      "/org/a11y/bus",
 706                                      introspection_data->interfaces[1],
 707                                      &status_vtable,
 708                                      _global_app,
 709                                      NULL,
 710                                      NULL);
 711 }
 712
 713 static void
 714 on_name_lost (GDBusConnection *connection,
 715               const gchar     *name,
 716               gpointer         user_data)
 717 {
 718   A11yBusLauncher *app = user_data;
 719   if (app->session_bus == NULL
 720       && connection == NULL
 721       && app->a11y_launch_error_message == NULL)
 722     app->a11y_launch_error_message = g_strdup ("Failed to connect to session bus");
 723   g_main_loop_quit (app->loop);
 724 }
 725
 726 static void
 727 on_name_acquired (GDBusConnection *connection,
 728                   const gchar     *name,
 729                   gpointer         user_data)
 730 {
 731   g_bus_watch_name (G_BUS_TYPE_SESSION,
 732                     "org.gnome.SessionManager",
 733                     G_BUS_NAME_WATCHER_FLAGS_NONE,
 734                     name_appeared_handler, NULL,
 735                     user_data, NULL);
 736 }
 737
 738 static int sigterm_pipefd[2];
 739
 740 static void
 741 sigterm_handler (int signum)
 742 {
 743   write (sigterm_pipefd[1], "X", 1);
 744 }
 745
 746 static gboolean
 747 on_sigterm_pipe (GIOChannel  *channel,
 748                  GIOCondition condition,
 749                  gpointer     data)
 750 {
 751   A11yBusLauncher *app = data;
 752
 753   g_main_loop_quit (app->loop);
 754
 755   return FALSE;
 756 }
 757
 758 static void
 759 init_sigterm_handling (A11yBusLauncher *app)
 760 {
 761   GIOChannel *sigterm_channel;
 762
 763   if (pipe (sigterm_pipefd) < 0)
 764     g_error ("Failed to create pipe: %s", strerror (errno));
 765   signal (SIGTERM, sigterm_handler);
 766
 767   sigterm_channel = g_io_channel_unix_new (sigterm_pipefd[0]);
 768   g_io_add_watch (sigterm_channel,
 769                   G_IO_IN | G_IO_ERR | G_IO_HUP,
 770                   on_sigterm_pipe,
 771                   app);
 772 }
 773
 774 static gboolean
 775 already_running ()
 776 {
 777 #ifdef HAVE_X11
 778   Atom AT_SPI_BUS;
 779   Atom actual_type;
 780   Display *bridge_display;
 781   int actual_format;
 782   unsigned char *data = NULL;
 783   unsigned long nitems;
 784   unsigned long leftover;
 785   gboolean result = FALSE;
 786
 787   bridge_display = XOpenDisplay (NULL);
 788   if (!bridge_display)
 789               return FALSE;
 790
 791   AT_SPI_BUS = XInternAtom (bridge_display, "AT_SPI_BUS", False);
 792   XGetWindowProperty (bridge_display,
 793                       XDefaultRootWindow (bridge_display),
 794                       AT_SPI_BUS, 0L,
 795                       (long) BUFSIZ, False,
 796                       (Atom) 31, &actual_type, &actual_format,
 797                       &nitems, &leftover, &data);
 798
 799   if (data)
 800   {
 801     GDBusConnection *bus;
 802     bus = g_dbus_connection_new_for_address_sync ((const gchar *)data, 0,
 803                                                   NULL, NULL, NULL);
 804     if (bus != NULL)
 805       {
 806         result = TRUE;
 807         g_object_unref (bus);
 808       }
 809   }
 810
 811   XCloseDisplay (bridge_display);
 812   return result;
 813 #else
 814   return FALSE;
 815 #endif
 816 }
 817
 818 static GSettings *
 819 get_schema (const gchar *name)
 820 {
 821 #if GLIB_CHECK_VERSION (2, 32, 0)
 822   GSettingsSchemaSource *source = g_settings_schema_source_get_default ();
 823   GSettingsSchema *schema = g_settings_schema_source_lookup (source, name, FALSE);
 824
 825   if (schema == NULL)
 826     return NULL;
 827
 828   return g_settings_new_full (schema, NULL, NULL);
 829 #else
 830   const char * const *schemas = NULL;
 831   gint i;
 832
 833   schemas = g_settings_list_schemas ();
 834   for (i = 0; schemas[i]; i++)
 835   {
 836     if (!strcmp (schemas[i], name))
 837       return g_settings_new (schemas[i]);
 838   }
 839
 840   return NULL;
 841 #endif
 842 }
 843
 844 static void
 845 gsettings_key_changed (GSettings *gsettings, const gchar *key, void *user_data)
 846 {
 847   gboolean new_val = g_settings_get_boolean (gsettings, key);
 848
 849   if (!strcmp (key, "toolkit-accessibility"))
 850     handle_a11y_enabled_change (_global_app, new_val, FALSE);
 851   else if (!strcmp (key, "screen-reader-enabled"))
 852     handle_screen_reader_enabled_change (_global_app, new_val, FALSE);
 853 }
 854
 855 int
 856 main (int    argc,
 857       char **argv)
 858 {
 859   gboolean a11y_set = FALSE;
 860   gboolean screen_reader_set = FALSE;
 861   gint i;
 862
 863   if (already_running ())
 864     return 0;
 865
 866   _global_app = g_slice_new0 (A11yBusLauncher);
 867   _global_app->loop = g_main_loop_new (NULL, FALSE);
 868
 869   for (i = 1; i < argc; i++)
 870     {
 871       if (!strcmp (argv[i], "--launch-immediately"))
 872         _global_app->launch_immediately = TRUE;
 873       else if (sscanf (argv[i], "--a11y=%d", &_global_app->a11y_enabled) == 1)
 874         a11y_set = TRUE;
 875       else if (sscanf (argv[i], "--screen-reader=%d",
 876                        &_global_app->screen_reader_enabled) == 1)
 877         screen_reader_set = TRUE;
 878     else
 879       g_error ("usage: %s [--launch-immediately] [--a11y=0|1] [--screen-reader=0|1]", argv[0]);
 880     }
 881
 882   _global_app->interface_schema = get_schema ("org.gnome.desktop.interface");
 883   _global_app->a11y_schema = get_schema ("org.gnome.desktop.a11y.applications");
 884
 885   if (!a11y_set)
 886     {
 887       _global_app->a11y_enabled = _global_app->interface_schema
 888                                   ? g_settings_get_boolean (_global_app->interface_schema, "toolkit-accessibility")
 889                                   : _global_app->launch_immediately;
 890     }
 891
 892   if (!screen_reader_set)
 893     {
 894       _global_app->screen_reader_enabled = _global_app->a11y_schema
 895                                   ? g_settings_get_boolean (_global_app->a11y_schema, "screen-reader-enabled")
 896                                   : FALSE;
 897     }
 898
 899   if (_global_app->interface_schema)
 900     g_signal_connect (_global_app->interface_schema,
 901                       "changed::toolkit-accessibility",
 902                       G_CALLBACK (gsettings_key_changed), _global_app);
 903
 904   if (_global_app->a11y_schema)
 905     g_signal_connect (_global_app->a11y_schema,
 906                       "changed::screen-reader-enabled",
 907                       G_CALLBACK (gsettings_key_changed), _global_app);
 908
 909   init_sigterm_handling (_global_app);
 910
 911   introspection_data = g_dbus_node_info_new_for_xml (introspection_xml, NULL);
 912   g_assert (introspection_data != NULL);
 913
 914   _global_app->name_owner_id =
 915     g_bus_own_name (G_BUS_TYPE_SESSION,
 916                     "org.a11y.Bus",
 917                     G_BUS_NAME_OWNER_FLAGS_ALLOW_REPLACEMENT,
 918                     on_bus_acquired,
 919                     on_name_acquired,
 920                     on_name_lost,
 921                     _global_app,
 922                     NULL);
 923
 924   g_main_loop_run (_global_app->loop);
 925
 926   if (_global_app->a11y_bus_pid > 0)
 927     kill (_global_app->a11y_bus_pid, SIGTERM);
 928
 929   /* Clear the X property if our bus is gone; in the case where e.g.
 930    * GDM is launching a login on an X server it was using before,
 931    * we don't want early login processes to pick up the stale address.
 932    */
 933 #ifdef HAVE_X11
 934   {
 935     Display *display = XOpenDisplay (NULL);
 936     if (display)
 937       {
 938         Atom bus_address_atom = XInternAtom (display, "AT_SPI_BUS", False);
 939         XDeleteProperty (display,
 940                          XDefaultRootWindow (display),
 941                          bus_address_atom);
 942
 943         XFlush (display);
 944         XCloseDisplay (display);
 945       }
 946   }
 947 #endif
 948
 949   if (_global_app->a11y_launch_error_message)
 950     {
 951       g_printerr ("Failed to launch bus: %s", _global_app->a11y_launch_error_message);
 952       return 1;
 953     }
 954   return 0;
 955 }