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fune/accessible/atk/Platform.cpp
Mike Hommey 693d7516ba Bug 1377445 - Use dlsym for atk_bridge_adaptor_init. r=eeejay 
Currently, we use a weak symbol to call atk_bridge_adaptor_init, but for
some reason, this stops working when removing the mozgtk stub library
(which we can do now that we don't need gtk+2 support at all), in a way
similar to bug 1368363.

We've been using a weak symbol because atk-bridge 2.0 was not guaranteed
to be enabled in gtk+3 back when this was added, but things have changed
since then, and gtk+3 always requires atk-bridge 2.0... ... on X11.
Unfortunately, that's not the case on Wayland, and a gtk+3 built with
Wayland support only will not depend on atk-bridge 2.0. So all in all,
we're back to square one, and because this fails to build, we need
another approach.

It turns out that other approach was in place for gtk+2, in the form of
dlopen/dlsym, the code for which somehow survived the years despite
Firefox not actually using gtk+2 for accessibility.

So we repurpose that code to load atk-bridge 2.0, which also happens to
not be a gtk+3 module, so we can remove the whole code path that tries to
load it from the gtk-3.0/modules path.

Differential Revision: https://phabricator.services.mozilla.com/D111996
2021-04-20 01:57:02 +00:00

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/* -*- 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 "nsIGSettingsService.h"
#include "nsMai.h"
#include "nsServiceManagerUtils.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, atkMicroVersion = 0;
GType (*gAtkTableCellGetTypeFunc)();
extern "C" {
typedef GType (*AtkGetTypeType)(void);
typedef void (*AtkBridgeAdaptorInit)(int*, char**[]);
}
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 AtkBridgeModule {
const char* libName;
PRLibrary* lib;
const char* initName;
AtkBridgeAdaptorInit init;
};
static AtkBridgeModule sAtkBridge = {"libatk-bridge-2.0.so.0", nullptr,
"atk_bridge_adaptor_init", nullptr};
static nsresult LoadGtkModule(AtkBridgeModule& aModule) {
NS_ENSURE_ARG(aModule.libName);
if (!(aModule.lib = PR_LoadLibrary(aModule.libName))) {
return NS_ERROR_FAILURE;
}
// we have loaded the library, try to get the function ptrs
if (!(aModule.init = (AtkBridgeAdaptorInit)PR_FindFunctionSymbol(
aModule.lib, aModule.initName))) {
// 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;
}
gAtkTableCellGetTypeFunc =
(GType(*)())PR_FindFunctionSymbol(sATKLib, "atk_table_cell_get_type");
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 (atkMajorVersion != 0L) {
atkMinorVersion = strtol(endPtr + 1, &endPtr, 10);
if (atkMinorVersion != 0L) {
atkMicroVersion = strtol(endPtr + 1, &endPtr, 10);
}
}
}
}
// 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");
nsresult rv = LoadGtkModule(sAtkBridge);
if (NS_SUCCEEDED(rv)) {
(*sAtkBridge.init)(nullptr, nullptr);
}
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
// PR_UnloadLibrary(sAtkBridge.lib);
sAtkBridge.lib = nullptr;
sAtkBridge.init = 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 GSettings
#define GSETINGS_A11Y_INTERFACE "org.gnome.desktop.interface"
#define GSETINGS_A11Y_KEY "toolkit-accessibility"
nsCOMPtr<nsIGSettingsService> gsettings =
do_GetService(NS_GSETTINGSSERVICE_CONTRACTID);
nsCOMPtr<nsIGSettingsCollection> a11y_settings;
if (gsettings) {
gsettings->GetCollectionForSchema(nsLiteralCString(GSETINGS_A11Y_INTERFACE),
getter_AddRefs(a11y_settings));
if (a11y_settings) {
a11y_settings->GetBoolean(nsLiteralCString(GSETINGS_A11Y_KEY),
&sShouldEnable);
}
}
return sShouldEnable;
}
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