gecko/accessible/atk/Platform.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "Platform.h"

#include "nsIAccessibleEvent.h"
#include "nsIGConfService.h"
#include "nsIServiceManager.h"
#include "nsMai.h"
#include "AtkSocketAccessible.h"
#include "prenv.h"
#include "prlink.h"

#ifdef MOZ_ENABLE_DBUS
#include <dbus/dbus.h>
#endif
#include <gtk/gtk.h>

using namespace mozilla;
using namespace mozilla::a11y;

int atkMajorVersion = 1, atkMinorVersion = 12;

extern "C" {
typedef GType (* AtkGetTypeType) (void);
typedef void (*GnomeAccessibilityInit) (void);
typedef void (*GnomeAccessibilityShutdown) (void);
}

static PRLibrary* sATKLib = nullptr;
static const char sATKLibName[] = "libatk-1.0.so.0";
static const char sATKHyperlinkImplGetTypeSymbol[] =
  "atk_hyperlink_impl_get_type";

gboolean toplevel_event_watcher(GSignalInvocationHint*, guint, const GValue*,
                                gpointer);
static bool sToplevel_event_hook_added = false;
static gulong sToplevel_show_hook = 0;
static gulong sToplevel_hide_hook = 0;

GType g_atk_hyperlink_impl_type = G_TYPE_INVALID;

struct GnomeAccessibilityModule
{
    const char *libName;
    PRLibrary *lib;
    const char *initName;
    GnomeAccessibilityInit init;
    const char *shutdownName;
    GnomeAccessibilityShutdown shutdown;
};

static GnomeAccessibilityModule sAtkBridge = {
#ifdef AIX
    "libatk-bridge.a(libatk-bridge.so.0)", nullptr,
#else
    "libatk-bridge.so", nullptr,
#endif
    "gnome_accessibility_module_init", nullptr,
    "gnome_accessibility_module_shutdown", nullptr
};

static GnomeAccessibilityModule sGail = {
    "libgail.so", nullptr,
    "gnome_accessibility_module_init", nullptr,
    "gnome_accessibility_module_shutdown", nullptr
};

static nsresult
LoadGtkModule(GnomeAccessibilityModule& aModule)
{
    NS_ENSURE_ARG(aModule.libName);

    if (!(aModule.lib = PR_LoadLibrary(aModule.libName))) {
        //try to load the module with "gtk-2.0/modules" appended
        char *curLibPath = PR_GetLibraryPath();
        nsAutoCString libPath(curLibPath);
#if defined(LINUX) && defined(__x86_64__)
        libPath.AppendLiteral(":/usr/lib64:/usr/lib");
#else
        libPath.AppendLiteral(":/usr/lib");
#endif
        PR_FreeLibraryName(curLibPath);

        int16_t loc1 = 0, loc2 = 0;
        int16_t subLen = 0;
        while (loc2 >= 0) {
            loc2 = libPath.FindChar(':', loc1);
            if (loc2 < 0)
                subLen = libPath.Length() - loc1;
            else
                subLen = loc2 - loc1;
            nsAutoCString sub(Substring(libPath, loc1, subLen));
            sub.AppendLiteral("/gtk-2.0/modules/");
            sub.Append(aModule.libName);
            aModule.lib = PR_LoadLibrary(sub.get());
            if (aModule.lib)
                break;

            loc1 = loc2+1;
        }
        if (!aModule.lib)
            return NS_ERROR_FAILURE;
    }

    //we have loaded the library, try to get the function ptrs
    if (!(aModule.init = PR_FindFunctionSymbol(aModule.lib,
                                               aModule.initName)) ||
        !(aModule.shutdown = PR_FindFunctionSymbol(aModule.lib,
                                                   aModule.shutdownName))) {

        //fail, :(
        PR_UnloadLibrary(aModule.lib);
        aModule.lib = nullptr;
        return NS_ERROR_FAILURE;
    }
    return NS_OK;
}

void
a11y::PlatformInit()
{
  if (!ShouldA11yBeEnabled())
    return;

  sATKLib = PR_LoadLibrary(sATKLibName);
  if (!sATKLib)
    return;

  AtkGetTypeType pfn_atk_hyperlink_impl_get_type =
    (AtkGetTypeType) PR_FindFunctionSymbol(sATKLib, sATKHyperlinkImplGetTypeSymbol);
  if (pfn_atk_hyperlink_impl_get_type)
    g_atk_hyperlink_impl_type = pfn_atk_hyperlink_impl_get_type();

  AtkGetTypeType pfn_atk_socket_get_type = (AtkGetTypeType)
    PR_FindFunctionSymbol(sATKLib, AtkSocketAccessible::sATKSocketGetTypeSymbol);
  if (pfn_atk_socket_get_type) {
    AtkSocketAccessible::g_atk_socket_type = pfn_atk_socket_get_type();
    AtkSocketAccessible::g_atk_socket_embed = (AtkSocketEmbedType)
      PR_FindFunctionSymbol(sATKLib, AtkSocketAccessible ::sATKSocketEmbedSymbol);
    AtkSocketAccessible::gCanEmbed =
      AtkSocketAccessible::g_atk_socket_type != G_TYPE_INVALID &&
      AtkSocketAccessible::g_atk_socket_embed;
  }

  const char* (*atkGetVersion)() =
    (const char* (*)()) PR_FindFunctionSymbol(sATKLib, "atk_get_version");
  if (atkGetVersion) {
    const char* version = atkGetVersion();
    if (version) {
      char* endPtr = nullptr;
      atkMajorVersion = strtol(version, &endPtr, 10);
      if (*endPtr == '.')
        atkMinorVersion = strtol(endPtr + 1, &endPtr, 10);
    }
  }

  // Load and initialize gail library.
  nsresult rv = LoadGtkModule(sGail);
  if (NS_SUCCEEDED(rv))
    (*sGail.init)();

  // Initialize the MAI Utility class, it will overwrite gail_util.
  g_type_class_unref(g_type_class_ref(mai_util_get_type()));

  // Init atk-bridge now
  PR_SetEnv("NO_AT_BRIDGE=0");
  rv = LoadGtkModule(sAtkBridge);
  if (NS_SUCCEEDED(rv)) {
    (*sAtkBridge.init)();
  }

  if (!sToplevel_event_hook_added) {
    sToplevel_event_hook_added = true;
    sToplevel_show_hook =
      g_signal_add_emission_hook(g_signal_lookup("show", GTK_TYPE_WINDOW),
                                 0, toplevel_event_watcher,
                                 reinterpret_cast<gpointer>(nsIAccessibleEvent::EVENT_SHOW),
                                 nullptr);
    sToplevel_hide_hook =
      g_signal_add_emission_hook(g_signal_lookup("hide", GTK_TYPE_WINDOW), 0,
                                 toplevel_event_watcher,
                                 reinterpret_cast<gpointer>(nsIAccessibleEvent::EVENT_HIDE),
                                 nullptr);
  }
}

void
a11y::PlatformShutdown()
{
    if (sToplevel_event_hook_added) {
      sToplevel_event_hook_added = false;
      g_signal_remove_emission_hook(g_signal_lookup("show", GTK_TYPE_WINDOW),
                                    sToplevel_show_hook);
      g_signal_remove_emission_hook(g_signal_lookup("hide", GTK_TYPE_WINDOW),
                                    sToplevel_hide_hook);
    }

    if (sAtkBridge.lib) {
        // Do not shutdown/unload atk-bridge,
        // an exit function registered will take care of it
        // if (sAtkBridge.shutdown)
        //     (*sAtkBridge.shutdown)();
        // PR_UnloadLibrary(sAtkBridge.lib);
        sAtkBridge.lib = nullptr;
        sAtkBridge.init = nullptr;
        sAtkBridge.shutdown = nullptr;
    }
    if (sGail.lib) {
        // Do not shutdown gail because
        // 1) Maybe it's not init-ed by us. e.g. GtkEmbed
        // 2) We need it to avoid assert in spi_atk_tidy_windows
        // if (sGail.shutdown)
        //   (*sGail.shutdown)();
        // PR_UnloadLibrary(sGail.lib);
        sGail.lib = nullptr;
        sGail.init = nullptr;
        sGail.shutdown = nullptr;
    }
    // if (sATKLib) {
    //     PR_UnloadLibrary(sATKLib);
    //     sATKLib = nullptr;
    // }
}

  static const char sAccEnv [] = "GNOME_ACCESSIBILITY";
#ifdef MOZ_ENABLE_DBUS
static DBusPendingCall *sPendingCall = nullptr;
#endif

void
a11y::PreInit()
{
#ifdef MOZ_ENABLE_DBUS
  static bool sChecked = FALSE;
  if (sChecked)
    return;

  sChecked = TRUE;

  // dbus is only checked if GNOME_ACCESSIBILITY is unset
  // also make sure that a session bus address is available to prevent dbus from
  // starting a new one.  Dbus confuses the test harness when it creates a new
  // process (see bug 693343)
  if (PR_GetEnv(sAccEnv) || !PR_GetEnv("DBUS_SESSION_BUS_ADDRESS"))
    return;

  DBusConnection* bus = dbus_bus_get(DBUS_BUS_SESSION, nullptr);
  if (!bus)
    return;

  dbus_connection_set_exit_on_disconnect(bus, FALSE);

  static const char* iface = "org.a11y.Status";
  static const char* member = "IsEnabled";
  DBusMessage *message;
  message = dbus_message_new_method_call("org.a11y.Bus", "/org/a11y/bus",
                                         "org.freedesktop.DBus.Properties",
                                         "Get");
  if (!message)
    goto dbus_done;

  dbus_message_append_args(message, DBUS_TYPE_STRING, &iface,
                           DBUS_TYPE_STRING, &member, DBUS_TYPE_INVALID);
  dbus_connection_send_with_reply(bus, message, &sPendingCall, 1000);
  dbus_message_unref(message);

dbus_done:
  dbus_connection_unref(bus);
#endif
}

bool
a11y::ShouldA11yBeEnabled()
{
  static bool sChecked = false, sShouldEnable = false;
  if (sChecked)
    return sShouldEnable;

  sChecked = true;

  EPlatformDisabledState disabledState = PlatformDisabledState();
  if (disabledState == ePlatformIsDisabled)
    return sShouldEnable = false;

  // check if accessibility enabled/disabled by environment variable
  const char* envValue = PR_GetEnv(sAccEnv);
  if (envValue)
    return sShouldEnable = !!atoi(envValue);

#ifdef MOZ_ENABLE_DBUS
  PreInit();
  bool dbusSuccess = false;
  DBusMessage *reply = nullptr;
  if (!sPendingCall)
    goto dbus_done;

  dbus_pending_call_block(sPendingCall);
  reply = dbus_pending_call_steal_reply(sPendingCall);
  dbus_pending_call_unref(sPendingCall);
  sPendingCall = nullptr;
  if (!reply ||
      dbus_message_get_type(reply) != DBUS_MESSAGE_TYPE_METHOD_RETURN ||
      strcmp(dbus_message_get_signature (reply), DBUS_TYPE_VARIANT_AS_STRING))
    goto dbus_done;

  DBusMessageIter iter, iter_variant, iter_struct;
  dbus_bool_t dResult;
  dbus_message_iter_init(reply, &iter);
  dbus_message_iter_recurse (&iter, &iter_variant);
  switch (dbus_message_iter_get_arg_type(&iter_variant)) {
    case DBUS_TYPE_STRUCT:
      // at-spi2-core 2.2.0-2.2.1 had a bug where it returned a struct
      dbus_message_iter_recurse(&iter_variant, &iter_struct);
      if (dbus_message_iter_get_arg_type(&iter_struct) == DBUS_TYPE_BOOLEAN) {
        dbus_message_iter_get_basic(&iter_struct, &dResult);
        sShouldEnable = dResult;
        dbusSuccess = true;
      }

      break;
    case DBUS_TYPE_BOOLEAN:
      dbus_message_iter_get_basic(&iter_variant, &dResult);
      sShouldEnable = dResult;
      dbusSuccess = true;
      break;
    default:
      break;
  }

dbus_done:
  if (reply)
    dbus_message_unref(reply);

  if (dbusSuccess)
    return sShouldEnable;
#endif

  //check gconf-2 setting
static const char sGconfAccessibilityKey[] =
    "/desktop/gnome/interface/accessibility";
  nsresult rv = NS_OK;
  nsCOMPtr<nsIGConfService> gconf =
    do_GetService(NS_GCONFSERVICE_CONTRACTID, &rv);
  if (NS_SUCCEEDED(rv) && gconf)
    gconf->GetBool(NS_LITERAL_CSTRING(sGconfAccessibilityKey), &sShouldEnable);

  return sShouldEnable;
}