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 Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 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  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with this library; if not, write to the
  19  * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  20  * Boston, MA 02110-1301, 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 #ifdef DBUS_BROKER
  43 #include <systemd/sd-login.h>
  44 #endif
  45 #include <sys/stat.h>
  46
  47 typedef enum {
  48   A11Y_BUS_STATE_IDLE = 0,
  49   A11Y_BUS_STATE_READING_ADDRESS,
  50   A11Y_BUS_STATE_RUNNING,
  51   A11Y_BUS_STATE_ERROR
  52 } A11yBusState;
  53
  54 typedef struct {
  55   GMainLoop *loop;
  56   gboolean launch_immediately;
  57   gboolean a11y_enabled;
  58   gboolean screen_reader_enabled;
  59   GDBusConnection *session_bus;
  60   GSettings *a11y_schema;
  61   GSettings *interface_schema;
  62   int name_owner_id;
  63
  64   GDBusProxy *client_proxy;
  65
  66   A11yBusState state;
  67   /* -1 == error, 0 == pending, > 0 == running */
  68   GPid a11y_bus_pid;
  69   char *socket_name;
  70   char *a11y_bus_address;
  71 #ifdef HAVE_X11
  72   gboolean x11_prop_set;
  73 #endif
  74   int pipefd[2];
  75   int listenfd;
  76   char *a11y_launch_error_message;
  77   GDBusProxy *sm_proxy;
  78 } A11yBusLauncher;
  79
  80 static A11yBusLauncher *_global_app = NULL;
  81
  82 static const gchar introspection_xml[] =
  83   "<node>"
  84   "  <interface name='org.a11y.Bus'>"
  85   "    <method name='GetAddress'>"
  86   "      <arg type='s' name='address' direction='out'/>"
  87   "    </method>"
  88   "  </interface>"
  89   "  <interface name='org.a11y.Status'>"
  90   "    <property name='IsEnabled' type='b' access='readwrite'/>"
  91   "    <property name='ScreenReaderEnabled' type='b' access='readwrite'/>"
  92   "  </interface>"
  93   "</node>";
  94 static GDBusNodeInfo *introspection_data = NULL;
  95
  96 static void
  97 respond_to_end_session (GDBusProxy *proxy)
  98 {
  99   GVariant *parameters;
 100
 101   parameters = g_variant_new ("(bs)", TRUE, "");
 102
 103   g_dbus_proxy_call (proxy,
 104                      "EndSessionResponse", parameters,
 105                      G_DBUS_CALL_FLAGS_NONE,
 106                      -1, NULL, NULL, NULL);
 107 }
 108
 109 static void
 110 g_signal_cb (GDBusProxy *proxy,
 111              gchar      *sender_name,
 112              gchar      *signal_name,
 113              GVariant   *parameters,
 114              gpointer    user_data)
 115 {
 116   A11yBusLauncher *app = user_data;
 117
 118   if (g_strcmp0 (signal_name, "QueryEndSession") == 0)
 119     respond_to_end_session (proxy);
 120   else if (g_strcmp0 (signal_name, "EndSession") == 0)
 121     respond_to_end_session (proxy);
 122   else if (g_strcmp0 (signal_name, "Stop") == 0)
 123     g_main_loop_quit (app->loop);
 124 }
 125
 126 static void
 127 client_proxy_ready_cb (GObject      *source_object,
 128                        GAsyncResult *res,
 129                        gpointer      user_data)
 130 {
 131   A11yBusLauncher *app = user_data;
 132   GError *error = NULL;
 133
 134   app->client_proxy = g_dbus_proxy_new_for_bus_finish (res, &error);
 135
 136   if (error != NULL)
 137     {
 138       g_warning ("Failed to get a client proxy: %s", error->message);
 139       g_error_free (error);
 140
 141       return;
 142     }
 143
 144   g_signal_connect (app->client_proxy, "g-signal",
 145                     G_CALLBACK (g_signal_cb), app);
 146 }
 147
 148 static void
 149 client_registered (GObject *source,
 150                    GAsyncResult *result,
 151                    gpointer user_data)
 152 {
 153   A11yBusLauncher *app = user_data;
 154   GError *error = NULL;
 155   GVariant *variant;
 156   gchar *object_path;
 157   GDBusProxyFlags flags;
 158
 159   variant = g_dbus_proxy_call_finish (app->sm_proxy, result, &error);
 160   if (!variant)
 161     {
 162       if (error != NULL)
 163         {
 164           g_warning ("Failed to register client: %s", error->message);
 165           g_error_free (error);
 166         }
 167     }
 168   else
 169     {
 170       g_variant_get (variant, "(o)", &object_path);
 171       g_variant_unref (variant);
 172
 173       flags = G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES;
 174       g_dbus_proxy_new_for_bus (G_BUS_TYPE_SESSION, flags, NULL,
 175                                 "org.gnome.SessionManager", object_path,
 176                                 "org.gnome.SessionManager.ClientPrivate",
 177                                 NULL, client_proxy_ready_cb, app);
 178
 179       g_free (object_path);
 180     }
 181   g_clear_object (&app->sm_proxy);
 182 }
 183
 184 static void
 185 register_client (A11yBusLauncher *app)
 186 {
 187   GDBusProxyFlags flags;
 188   GError *error;
 189   const gchar *app_id;
 190   const gchar *autostart_id;
 191   gchar *client_startup_id;
 192   GVariant *parameters;
 193
 194   flags = G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES |
 195           G_DBUS_PROXY_FLAGS_DO_NOT_CONNECT_SIGNALS;
 196
 197   error = NULL;
 198   app->sm_proxy = g_dbus_proxy_new_sync (app->session_bus, flags, NULL,
 199                                          "org.gnome.SessionManager",
 200                                          "/org/gnome/SessionManager",
 201                                          "org.gnome.SessionManager",
 202                                          NULL, &error);
 203
 204   if (error != NULL)
 205     {
 206       g_warning ("Failed to get session manager proxy: %s", error->message);
 207       g_error_free (error);
 208
 209       return;
 210     }
 211
 212   app_id = "at-spi-bus-launcher";
 213   autostart_id = g_getenv ("DESKTOP_AUTOSTART_ID");
 214
 215   if (autostart_id != NULL)
 216     {
 217       client_startup_id = g_strdup (autostart_id);
 218       g_unsetenv ("DESKTOP_AUTOSTART_ID");
 219     }
 220   else
 221     {
 222       client_startup_id = g_strdup ("");
 223     }
 224
 225   parameters = g_variant_new ("(ss)", app_id, client_startup_id);
 226   g_free (client_startup_id);
 227
 228   error = NULL;
 229   g_dbus_proxy_call (app->sm_proxy,
 230                      "RegisterClient", parameters,
 231                      G_DBUS_CALL_FLAGS_NONE,
 232                      G_MAXINT, NULL, client_registered, app);
 233
 234 }
 235
 236 static void
 237 name_appeared_handler (GDBusConnection *connection,
 238                        const gchar     *name,
 239                        const gchar     *name_owner,
 240                        gpointer         user_data)
 241 {
 242   A11yBusLauncher *app = user_data;
 243
 244   register_client (app);
 245 }
 246
 247 /**
 248  * unix_read_all_fd_to_string:
 249  *
 250  * Read all data from a file descriptor to a C string buffer.
 251  */
 252 static gboolean
 253 unix_read_all_fd_to_string (int       fd,
 254                             char     *buf,
 255                             ssize_t   max_bytes,
 256                             char    **error_msg)
 257 {
 258   g_assert (max_bytes > 1);
 259   *error_msg = NULL;
 260
 261   max_bytes -= 1; /* allow space for nul terminator */
 262
 263   while (max_bytes > 1)
 264     {
 265       ssize_t bytes_read;
 266
 267     again:
 268       bytes_read = read (fd, buf, max_bytes);
 269
 270       if (bytes_read == 0)
 271         {
 272           break;
 273         }
 274       else if (bytes_read > 0)
 275         {
 276           buf += bytes_read;
 277           max_bytes -= bytes_read;
 278         }
 279       else if (errno == EINTR)
 280         {
 281           goto again;
 282         }
 283       else
 284         {
 285           int err_save = errno;
 286           *error_msg = g_strdup_printf ("Failed to read data from accessibility bus: %s", g_strerror (err_save));
 287           return FALSE;
 288         }
 289     }
 290
 291   *buf = '\0';
 292   return TRUE;
 293 }
 294
 295 static void
 296 on_bus_exited (GPid     pid,
 297                gint     status,
 298                gpointer data)
 299 {
 300   A11yBusLauncher *app = data;
 301
 302   app->a11y_bus_pid = -1;
 303   app->state = A11Y_BUS_STATE_ERROR;
 304   if (app->a11y_launch_error_message == NULL)
 305     {
 306       if (WIFEXITED (status))
 307         app->a11y_launch_error_message = g_strdup_printf ("Bus exited with code %d", WEXITSTATUS (status));
 308       else if (WIFSIGNALED (status))
 309         app->a11y_launch_error_message = g_strdup_printf ("Bus killed by signal %d", WTERMSIG (status));
 310       else if (WIFSTOPPED (status))
 311         app->a11y_launch_error_message = g_strdup_printf ("Bus stopped by signal %d", WSTOPSIG (status));
 312     }
 313   g_main_loop_quit (app->loop);
 314 }
 315
 316 #ifdef DBUS_DAEMON
 317 static gboolean
 318 ensure_a11y_bus_daemon (A11yBusLauncher *app, char *config_path)
 319 {
 320   char *address_param;
 321
 322   if (app->socket_name)
 323     {
 324       gchar *escaped_address = g_dbus_address_escape_value (app->socket_name);
 325       address_param = g_strconcat ("--address=unix:path=", escaped_address, NULL);
 326       g_free (escaped_address);
 327     }
 328   else
 329     {
 330       address_param = NULL;
 331     }
 332
 333   if (pipe (app->pipefd) < 0)
 334     g_error ("Failed to create pipe: %s", strerror (errno));
 335
 336   char *print_address_fd_param = g_strdup_printf ("%d", app->pipefd[1]);
 337
 338   char *argv[] = { DBUS_DAEMON, config_path, "--nofork", "--print-address", print_address_fd_param, address_param, NULL };
 339   gint source_fds[1] = { app->pipefd[1] };
 340   gint target_fds[1] = { app->pipefd[1] };
 341   G_STATIC_ASSERT (G_N_ELEMENTS (source_fds) == G_N_ELEMENTS (target_fds));
 342   GPid pid;
 343   char addr_buf[2048];
 344   GError *error = NULL;
 345   char *error_from_read;
 346
 347   g_clear_pointer (&app->a11y_launch_error_message, g_free);
 348
 349   if (!g_spawn_async_with_pipes_and_fds (NULL,
 350                                          (const gchar * const *) argv,
 351                                          NULL,
 352                                          G_SPAWN_SEARCH_PATH | G_SPAWN_DO_NOT_REAP_CHILD | G_SPAWN_LEAVE_DESCRIPTORS_OPEN,
 353                                          NULL, /* child_setup */
 354                                          app,
 355                                          -1, /* stdin_fd */
 356                                          -1, /* stdout_fd */
 357                                          -1, /* stdout_fd */
 358                                          source_fds,
 359                                          target_fds,
 360                                          G_N_ELEMENTS (source_fds), /* n_fds in source_fds and target_fds */
 361                                          &pid,
 362                                          NULL, /* stdin_pipe_out */
 363                                          NULL, /* stdout_pipe_out */
 364                                          NULL, /* stderr_pipe_out */
 365                                          &error))
 366     {
 367       app->a11y_bus_pid = -1;
 368       app->a11y_launch_error_message = g_strdup (error->message);
 369       g_clear_error (&error);
 370       g_free (address_param);
 371       g_free (print_address_fd_param);
 372       goto error;
 373     }
 374
 375   g_free (address_param);
 376   g_free (print_address_fd_param);
 377   close (app->pipefd[1]);
 378   app->pipefd[1] = -1;
 379
 380   g_child_watch_add (pid, on_bus_exited, app);
 381
 382   app->state = A11Y_BUS_STATE_READING_ADDRESS;
 383   app->a11y_bus_pid = pid;
 384   g_debug ("Launched a11y bus, child is %ld", (long) pid);
 385   error_from_read = NULL;
 386   if (!unix_read_all_fd_to_string (app->pipefd[0], addr_buf, sizeof (addr_buf), &error_from_read))
 387     {
 388       app->a11y_launch_error_message = error_from_read;
 389       kill (app->a11y_bus_pid, SIGTERM);
 390       g_spawn_close_pid (app->a11y_bus_pid);
 391       app->a11y_bus_pid = -1;
 392       goto error;
 393     }
 394   close (app->pipefd[0]);
 395   app->pipefd[0] = -1;
 396   app->state = A11Y_BUS_STATE_RUNNING;
 397
 398   /* Trim the trailing newline */
 399   app->a11y_bus_address = g_strchomp (g_strdup (addr_buf));
 400   g_debug ("a11y bus address: %s", app->a11y_bus_address);
 401
 402   return TRUE;
 403
 404 error:
 405   close (app->pipefd[0]);
 406   close (app->pipefd[1]);
 407   app->state = A11Y_BUS_STATE_ERROR;
 408
 409   return FALSE;
 410 }
 411 #else
 412 static gboolean
 413 ensure_a11y_bus_daemon (A11yBusLauncher *app, char *config_path)
 414 {
 415         return FALSE;
 416 }
 417 #endif
 418
 419 #ifdef DBUS_BROKER
 420 static void
 421 setup_bus_child_broker (gpointer data)
 422 {
 423   A11yBusLauncher *app = data;
 424   gchar *pid_str;
 425   (void) app;
 426
 427   dup2 (app->listenfd, 3);
 428   close (app->listenfd);
 429   g_setenv("LISTEN_FDS", "1", TRUE);
 430
 431   pid_str = g_strdup_printf("%u", getpid());
 432   g_setenv("LISTEN_PID", pid_str, TRUE);
 433   g_free(pid_str);
 434 }
 435
 436 static gboolean
 437 ensure_a11y_bus_broker (A11yBusLauncher *app, char *config_path)
 438 {
 439   char *argv[] = { DBUS_BROKER, config_path, "--scope", "user", NULL };
 440   char *unit;
 441   struct sockaddr_un addr = { .sun_family = AF_UNIX, "" };
 442   socklen_t addr_len = sizeof(addr);
 443   GPid pid;
 444   GError *error = NULL;
 445
 446   if (app->socket_name)
 447     {
 448       strcpy (addr.sun_path, app->socket_name);
 449       unlink (app->socket_name);
 450     }
 451
 452   /* This detects whether we are running under systemd. We only try to
 453    * use dbus-broker if we are running under systemd because D-Bus
 454    * service activation won't work otherwise.
 455    */
 456   if (sd_pid_get_user_unit (getpid (), &unit) >= 0)
 457     {
 458       free (unit);
 459     }
 460   else
 461     {
 462       app->state = A11Y_BUS_STATE_ERROR;
 463       return FALSE;
 464     }
 465
 466   if ((app->listenfd = socket (PF_UNIX, SOCK_STREAM | SOCK_NONBLOCK, 0)) < 0)
 467     g_error ("Failed to create listening socket: %s", strerror (errno));
 468
 469   if (bind (app->listenfd, (struct sockaddr *)&addr, addr_len) < 0)
 470     g_error ("Failed to bind listening socket: %s", strerror (errno));
 471
 472   if (!app->socket_name &&
 473       getsockname (app->listenfd, (struct sockaddr *)&addr, &addr_len) < 0)
 474     g_error ("Failed to get socket name for listening socket: %s", strerror(errno));
 475
 476   if (listen (app->listenfd, 1024) < 0)
 477     g_error ("Failed to listen on socket: %s", strerror(errno));
 478
 479   g_clear_pointer (&app->a11y_launch_error_message, g_free);
 480
 481   if (!g_spawn_async (NULL,
 482                       argv,
 483                       NULL,
 484                       G_SPAWN_SEARCH_PATH | G_SPAWN_DO_NOT_REAP_CHILD,
 485                       setup_bus_child_broker,
 486                       app,
 487                       &pid,
 488                       &error))
 489     {
 490       app->a11y_bus_pid = -1;
 491       app->a11y_launch_error_message = g_strdup (error->message);
 492       g_clear_error (&error);
 493       goto error;
 494     }
 495
 496   close (app->listenfd);
 497   app->listenfd = -1;
 498
 499   g_child_watch_add (pid, on_bus_exited, app);
 500   app->a11y_bus_pid = pid;
 501   g_debug ("Launched a11y bus, child is %ld", (long) pid);
 502   app->state = A11Y_BUS_STATE_RUNNING;
 503
 504   if (app->socket_name)
 505     app->a11y_bus_address = g_strconcat("unix:path=", addr.sun_path, NULL);
 506   else
 507     app->a11y_bus_address = g_strconcat("unix:abstract=", addr.sun_path + 1, NULL);
 508   g_debug ("a11y bus address: %s", app->a11y_bus_address);
 509
 510   return TRUE;
 511
 512 error:
 513   close (app->listenfd);
 514   app->state = A11Y_BUS_STATE_ERROR;
 515
 516   return FALSE;
 517 }
 518 #else
 519 static gboolean
 520 ensure_a11y_bus_broker (A11yBusLauncher *app, char *config_path)
 521 {
 522         return FALSE;
 523 }
 524 #endif
 525
 526 static gboolean
 527 ensure_a11y_bus (A11yBusLauncher *app)
 528 {
 529   char *config_path = NULL;
 530   gboolean success = FALSE;
 531   const gchar *xdg_runtime_dir;
 532
 533   if (app->a11y_bus_pid != 0)
 534     return FALSE;
 535
 536   if (g_file_test (SYSCONFDIR"/at-spi2/accessibility.conf", G_FILE_TEST_EXISTS))
 537       config_path = "--config-file="SYSCONFDIR"/at-spi2/accessibility.conf";
 538   else
 539       config_path = "--config-file="DATADIR"/defaults/at-spi2/accessibility.conf";
 540
 541     xdg_runtime_dir = g_get_user_runtime_dir ();
 542     if (xdg_runtime_dir)
 543       {
 544         const gchar *display = g_getenv ("DISPLAY");
 545         gchar *at_spi_dir = g_strconcat (xdg_runtime_dir, "/at-spi", NULL);
 546         gchar *p;
 547         mkdir (xdg_runtime_dir, 0700);
 548         if (!g_path_is_absolute (at_spi_dir))
 549         {
 550           gchar *new_dir = g_canonicalize_filename (at_spi_dir, NULL);
 551           g_free (at_spi_dir);
 552           at_spi_dir = new_dir;
 553         }
 554         if (mkdir (at_spi_dir, 0700) == 0 || errno == EEXIST)
 555           {
 556             app->socket_name = g_strconcat (at_spi_dir, "/bus", display, NULL);
 557             g_free (at_spi_dir);
 558             p = strchr (app->socket_name, ':');
 559             if (p)
 560               *p = '_';
 561             if (strlen (app->socket_name) >= 100)
 562               {
 563                 g_free (app->socket_name);
 564                 app->socket_name = NULL;
 565               }
 566           }
 567         else
 568           g_free (at_spi_dir);
 569       }
 570
 571 #ifdef WANT_DBUS_BROKER
 572     success = ensure_a11y_bus_broker (app, config_path);
 573     if (!success)
 574       {
 575         if (!ensure_a11y_bus_daemon (app, config_path))
 576             return FALSE;
 577       }
 578 #else
 579     success = ensure_a11y_bus_daemon (app, config_path);
 580     if (!success)
 581       {
 582         if (!ensure_a11y_bus_broker (app, config_path))
 583             return FALSE;
 584       }
 585 #endif
 586
 587 #ifdef HAVE_X11
 588   if (g_getenv ("DISPLAY") != NULL && g_getenv ("WAYLAND_DISPLAY") == NULL)
 589     {
 590       Display *display = XOpenDisplay (NULL);
 591       if (display)
 592         {
 593           Atom bus_address_atom = XInternAtom (display, "AT_SPI_BUS", False);
 594           XChangeProperty (display,
 595                            XDefaultRootWindow (display),
 596                            bus_address_atom,
 597                            XA_STRING, 8, PropModeReplace,
 598                            (guchar *) app->a11y_bus_address, strlen (app->a11y_bus_address));
 599           XFlush (display);
 600           XCloseDisplay (display);
 601           app->x11_prop_set = TRUE;
 602         }
 603     }
 604 #endif
 605
 606   return TRUE;
 607 }
 608
 609 static void
 610 handle_method_call (GDBusConnection       *connection,
 611                     const gchar           *sender,
 612                     const gchar           *object_path,
 613                     const gchar           *interface_name,
 614                     const gchar           *method_name,
 615                     GVariant              *parameters,
 616                     GDBusMethodInvocation *invocation,
 617                     gpointer               user_data)
 618 {
 619   A11yBusLauncher *app = user_data;
 620
 621   if (g_strcmp0 (method_name, "GetAddress") == 0)
 622     {
 623       ensure_a11y_bus (app);
 624       if (app->a11y_bus_pid > 0)
 625         g_dbus_method_invocation_return_value (invocation,
 626                                                g_variant_new ("(s)", app->a11y_bus_address));
 627       else
 628         g_dbus_method_invocation_return_dbus_error (invocation,
 629                                                     "org.a11y.Bus.Error",
 630                                                     app->a11y_launch_error_message);
 631     }
 632 }
 633
 634 static GVariant *
 635 handle_get_property  (GDBusConnection       *connection,
 636                       const gchar           *sender,
 637                       const gchar           *object_path,
 638                       const gchar           *interface_name,
 639                       const gchar           *property_name,
 640                     GError **error,
 641                     gpointer               user_data)
 642 {
 643   A11yBusLauncher *app = user_data;
 644
 645   if (g_strcmp0 (property_name, "IsEnabled") == 0)
 646     return g_variant_new ("b", app->a11y_enabled);
 647   else if (g_strcmp0 (property_name, "ScreenReaderEnabled") == 0)
 648     return g_variant_new ("b", app->screen_reader_enabled);
 649   else
 650     return NULL;
 651 }
 652
 653 static void
 654 handle_a11y_enabled_change (A11yBusLauncher *app, gboolean enabled,
 655                                gboolean notify_gsettings)
 656 {
 657   GVariantBuilder builder;
 658   GVariantBuilder invalidated_builder;
 659
 660   if (enabled == app->a11y_enabled)
 661     return;
 662
 663   app->a11y_enabled = enabled;
 664
 665   if (notify_gsettings && app->interface_schema)
 666     {
 667       g_settings_set_boolean (app->interface_schema, "toolkit-accessibility",
 668                               enabled);
 669       g_settings_sync ();
 670     }
 671
 672   g_variant_builder_init (&builder, G_VARIANT_TYPE_ARRAY);
 673   g_variant_builder_init (&invalidated_builder, G_VARIANT_TYPE ("as"));
 674   g_variant_builder_add (&builder, "{sv}", "IsEnabled",
 675                          g_variant_new_boolean (enabled));
 676
 677   g_dbus_connection_emit_signal (app->session_bus, NULL, "/org/a11y/bus",
 678                                  "org.freedesktop.DBus.Properties",
 679                                  "PropertiesChanged",
 680                                  g_variant_new ("(sa{sv}as)", "org.a11y.Status",
 681                                                 &builder,
 682                                                 &invalidated_builder),
 683                                  NULL);
 684
 685   g_variant_builder_clear (&builder);
 686   g_variant_builder_clear (&invalidated_builder);
 687 }
 688
 689 static void
 690 handle_screen_reader_enabled_change (A11yBusLauncher *app, gboolean enabled,
 691                                gboolean notify_gsettings)
 692 {
 693   GVariantBuilder builder;
 694   GVariantBuilder invalidated_builder;
 695
 696   if (enabled == app->screen_reader_enabled)
 697     return;
 698
 699   /* If the screen reader is being enabled, we should enable accessibility
 700    * if it isn't enabled already */
 701   if (enabled)
 702     handle_a11y_enabled_change (app, enabled, notify_gsettings);
 703
 704   app->screen_reader_enabled = enabled;
 705
 706   if (notify_gsettings && app->a11y_schema)
 707     {
 708       g_settings_set_boolean (app->a11y_schema, "screen-reader-enabled",
 709                               enabled);
 710       g_settings_sync ();
 711     }
 712
 713   g_variant_builder_init (&builder, G_VARIANT_TYPE_ARRAY);
 714   g_variant_builder_init (&invalidated_builder, G_VARIANT_TYPE ("as"));
 715   g_variant_builder_add (&builder, "{sv}", "ScreenReaderEnabled",
 716                          g_variant_new_boolean (enabled));
 717
 718   g_dbus_connection_emit_signal (app->session_bus, NULL, "/org/a11y/bus",
 719                                  "org.freedesktop.DBus.Properties",
 720                                  "PropertiesChanged",
 721                                  g_variant_new ("(sa{sv}as)", "org.a11y.Status",
 722                                                 &builder,
 723                                                 &invalidated_builder),
 724                                  NULL);
 725
 726   g_variant_builder_clear (&builder);
 727   g_variant_builder_clear (&invalidated_builder);
 728 }
 729
 730 static gboolean
 731 handle_set_property  (GDBusConnection       *connection,
 732                       const gchar           *sender,
 733                       const gchar           *object_path,
 734                       const gchar           *interface_name,
 735                       const gchar           *property_name,
 736                       GVariant *value,
 737                     GError **error,
 738                     gpointer               user_data)
 739 {
 740   A11yBusLauncher *app = user_data;
 741   const gchar *type = g_variant_get_type_string (value);
 742   gboolean enabled;
 743
 744   if (g_strcmp0 (type, "b") != 0)
 745     {
 746       g_set_error (error, G_DBUS_ERROR, G_DBUS_ERROR_INVALID_ARGS,
 747                        "org.a11y.Status.%s expects a boolean but got %s", property_name, type);
 748       return FALSE;
 749     }
 750
 751   enabled = g_variant_get_boolean (value);
 752
 753   if (g_strcmp0 (property_name, "IsEnabled") == 0)
 754     {
 755       handle_a11y_enabled_change (app, enabled, TRUE);
 756       return TRUE;
 757     }
 758   else if (g_strcmp0 (property_name, "ScreenReaderEnabled") == 0)
 759     {
 760       handle_screen_reader_enabled_change (app, enabled, TRUE);
 761       return TRUE;
 762     }
 763   else
 764     {
 765       g_set_error (error, G_DBUS_ERROR, G_DBUS_ERROR_INVALID_ARGS,
 766                        "Unknown property '%s'", property_name);
 767       return FALSE;
 768     }
 769 }
 770
 771 static const GDBusInterfaceVTable bus_vtable =
 772 {
 773   handle_method_call,
 774   NULL, /* handle_get_property, */
 775   NULL  /* handle_set_property */
 776 };
 777
 778 static const GDBusInterfaceVTable status_vtable =
 779 {
 780   NULL, /* handle_method_call */
 781   handle_get_property,
 782   handle_set_property
 783 };
 784
 785 static void
 786 on_bus_acquired (GDBusConnection *connection,
 787                  const gchar     *name,
 788                  gpointer         user_data)
 789 {
 790   A11yBusLauncher *app = user_data;
 791   GError *error;
 792   guint registration_id;
 793
 794   if (connection == NULL)
 795     {
 796       g_main_loop_quit (app->loop);
 797       return;
 798     }
 799   app->session_bus = connection;
 800
 801   error = NULL;
 802   registration_id = g_dbus_connection_register_object (connection,
 803                                                        "/org/a11y/bus",
 804                                                        introspection_data->interfaces[0],
 805                                                        &bus_vtable,
 806                                                        _global_app,
 807                                                        NULL,
 808                                                        &error);
 809   if (registration_id == 0)
 810     {
 811       g_error ("%s", error->message);
 812       g_clear_error (&error);
 813     }
 814
 815   g_dbus_connection_register_object (connection,
 816                                      "/org/a11y/bus",
 817                                      introspection_data->interfaces[1],
 818                                      &status_vtable,
 819                                      _global_app,
 820                                      NULL,
 821                                      NULL);
 822 }
 823
 824 static void
 825 on_name_lost (GDBusConnection *connection,
 826               const gchar     *name,
 827               gpointer         user_data)
 828 {
 829   A11yBusLauncher *app = user_data;
 830   if (app->session_bus == NULL
 831       && connection == NULL
 832       && app->a11y_launch_error_message == NULL)
 833     app->a11y_launch_error_message = g_strdup ("Failed to connect to session bus");
 834   g_main_loop_quit (app->loop);
 835 }
 836
 837 static void
 838 on_name_acquired (GDBusConnection *connection,
 839                   const gchar     *name,
 840                   gpointer         user_data)
 841 {
 842   A11yBusLauncher *app = user_data;
 843
 844   if (app->launch_immediately)
 845     {
 846       ensure_a11y_bus (app);
 847       if (app->state == A11Y_BUS_STATE_ERROR)
 848         {
 849           g_main_loop_quit (app->loop);
 850           return;
 851         }
 852     }
 853
 854   g_bus_watch_name (G_BUS_TYPE_SESSION,
 855                     "org.gnome.SessionManager",
 856                     G_BUS_NAME_WATCHER_FLAGS_NONE,
 857                     name_appeared_handler, NULL,
 858                     user_data, NULL);
 859 }
 860
 861 static int sigterm_pipefd[2];
 862
 863 static void
 864 sigterm_handler (int signum)
 865 {
 866   write (sigterm_pipefd[1], "X", 1);
 867 }
 868
 869 static gboolean
 870 on_sigterm_pipe (GIOChannel  *channel,
 871                  GIOCondition condition,
 872                  gpointer     data)
 873 {
 874   A11yBusLauncher *app = data;
 875
 876   g_main_loop_quit (app->loop);
 877
 878   return FALSE;
 879 }
 880
 881 static void
 882 init_sigterm_handling (A11yBusLauncher *app)
 883 {
 884   GIOChannel *sigterm_channel;
 885
 886   if (pipe (sigterm_pipefd) < 0)
 887     g_error ("Failed to create pipe: %s", strerror (errno));
 888   signal (SIGTERM, sigterm_handler);
 889
 890   sigterm_channel = g_io_channel_unix_new (sigterm_pipefd[0]);
 891   g_io_add_watch (sigterm_channel,
 892                   G_IO_IN | G_IO_ERR | G_IO_HUP,
 893                   on_sigterm_pipe,
 894                   app);
 895 }
 896
 897 static GSettings *
 898 get_schema (const gchar *name)
 899 {
 900 #if GLIB_CHECK_VERSION (2, 32, 0)
 901   GSettingsSchemaSource *source = g_settings_schema_source_get_default ();
 902   if (!source)
 903     {
 904       g_error ("Cannot get the default GSettingsSchemaSource - is the gsettings-desktop-schemas package installed?");
 905     }
 906
 907   GSettingsSchema *schema = g_settings_schema_source_lookup (source, name, FALSE);
 908
 909   if (schema == NULL)
 910     return NULL;
 911
 912   return g_settings_new_full (schema, NULL, NULL);
 913 #else
 914   const char * const *schemas = NULL;
 915   gint i;
 916
 917   schemas = g_settings_list_schemas ();
 918   for (i = 0; schemas[i]; i++)
 919   {
 920     if (!strcmp (schemas[i], name))
 921       return g_settings_new (schemas[i]);
 922   }
 923
 924   return NULL;
 925 #endif
 926 }
 927
 928 static void
 929 gsettings_key_changed (GSettings *gsettings, const gchar *key, void *user_data)
 930 {
 931   gboolean new_val = g_settings_get_boolean (gsettings, key);
 932
 933   if (!strcmp (key, "toolkit-accessibility"))
 934     handle_a11y_enabled_change (_global_app, new_val, FALSE);
 935   else if (!strcmp (key, "screen-reader-enabled"))
 936     handle_screen_reader_enabled_change (_global_app, new_val, FALSE);
 937 }
 938
 939 int
 940 main (int    argc,
 941       char **argv)
 942 {
 943   gboolean a11y_set = FALSE;
 944   gboolean screen_reader_set = FALSE;
 945   gint i;
 946
 947   _global_app = g_new0 (A11yBusLauncher, 1);
 948   _global_app->loop = g_main_loop_new (NULL, FALSE);
 949
 950   for (i = 1; i < argc; i++)
 951     {
 952       if (!strcmp (argv[i], "--launch-immediately"))
 953         _global_app->launch_immediately = TRUE;
 954       else if (sscanf (argv[i], "--a11y=%d", &_global_app->a11y_enabled) == 1)
 955         a11y_set = TRUE;
 956       else if (sscanf (argv[i], "--screen-reader=%d",
 957                        &_global_app->screen_reader_enabled) == 1)
 958         screen_reader_set = TRUE;
 959     else
 960       g_error ("usage: %s [--launch-immediately] [--a11y=0|1] [--screen-reader=0|1]", argv[0]);
 961     }
 962
 963   _global_app->interface_schema = get_schema ("org.gnome.desktop.interface");
 964   _global_app->a11y_schema = get_schema ("org.gnome.desktop.a11y.applications");
 965
 966   if (!a11y_set)
 967     {
 968       _global_app->a11y_enabled = _global_app->interface_schema
 969                                   ? g_settings_get_boolean (_global_app->interface_schema, "toolkit-accessibility")
 970                                   : _global_app->launch_immediately;
 971     }
 972
 973   if (!screen_reader_set)
 974     {
 975       _global_app->screen_reader_enabled = _global_app->a11y_schema
 976                                   ? g_settings_get_boolean (_global_app->a11y_schema, "screen-reader-enabled")
 977                                   : FALSE;
 978     }
 979
 980   if (_global_app->interface_schema)
 981     g_signal_connect (_global_app->interface_schema,
 982                       "changed::toolkit-accessibility",
 983                       G_CALLBACK (gsettings_key_changed), _global_app);
 984
 985   if (_global_app->a11y_schema)
 986     g_signal_connect (_global_app->a11y_schema,
 987                       "changed::screen-reader-enabled",
 988                       G_CALLBACK (gsettings_key_changed), _global_app);
 989
 990   init_sigterm_handling (_global_app);
 991
 992   introspection_data = g_dbus_node_info_new_for_xml (introspection_xml, NULL);
 993   g_assert (introspection_data != NULL);
 994
 995   _global_app->name_owner_id =
 996     g_bus_own_name (G_BUS_TYPE_SESSION,
 997                     "org.a11y.Bus",
 998                     G_BUS_NAME_OWNER_FLAGS_ALLOW_REPLACEMENT,
 999                     on_bus_acquired,
1000                     on_name_acquired,
1001                     on_name_lost,
1002                     _global_app,
1003                     NULL);
1004
1005   g_main_loop_run (_global_app->loop);
1006
1007   if (_global_app->a11y_bus_pid > 0)
1008     {
1009       kill (_global_app->a11y_bus_pid, SIGTERM);
1010       g_spawn_close_pid (_global_app->a11y_bus_pid);
1011       _global_app->a11y_bus_pid = -1;
1012     }
1013
1014   /* Clear the X property if our bus is gone; in the case where e.g.
1015    * GDM is launching a login on an X server it was using before,
1016    * we don't want early login processes to pick up the stale address.
1017    */
1018 #ifdef HAVE_X11
1019   if (_global_app->x11_prop_set)
1020     {
1021       Display *display = XOpenDisplay (NULL);
1022       if (display)
1023         {
1024           Atom bus_address_atom = XInternAtom (display, "AT_SPI_BUS", False);
1025           XDeleteProperty (display,
1026                            XDefaultRootWindow (display),
1027                            bus_address_atom);
1028
1029           XFlush (display);
1030           XCloseDisplay (display);
1031         }
1032     }
1033 #endif
1034
1035   if (_global_app->a11y_launch_error_message)
1036     {
1037       g_printerr ("Failed to launch bus: %s", _global_app->a11y_launch_error_message);
1038       return 1;
1039     }
1040   return 0;
1041 }