[Linux]Fix a potential crash issue in gtk_im_context_wrapper.cc

chrome/browser/renderer_host/gtk_im_context_wrapper.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/renderer_host/gtk_im_context_wrapper.h"
 
 #include <gdk/gdk.h>
 #include <gdk/gdkkeysyms.h>
 #include <gtk/gtk.h>
 #include <algorithm>
@@ skipping 190 matching lines @@
   // enabled by WebKit.
   if (is_enabled_)
     gtk_im_context_focus_in(context_);
 
   // context_simple_ is always enabled.
   // Actually it doesn't care focus state at all.
   gtk_im_context_focus_in(context_simple_);
 
   // Enables RenderWidget's IME related events, so that we can be notified
   // when WebKit wants to enable or disable IME.
-  host_view_->GetRenderWidgetHost()->SetInputMethodActive(true);
+  if (host_view_->GetRenderWidgetHost())

[satorux1, 2010/06/24 04:19:36]

host_view_ is guaranteed not to be NULL, right?

[James Su, 2010/06/24 04:21:46]

Yes. GtkIMContextWrapper object will be destroyed along with the |host_view_|
object.

+    host_view_->GetRenderWidgetHost()->SetInputMethodActive(true);
 }
 
 void GtkIMContextWrapper::OnFocusOut() {
   if (!is_focused_)
     return;
 
   // Tracks the focused state so that we won't give focus to the
   // GtkIMContext object unexpectly.
   is_focused_ = false;
 
   // Notify the GtkIMContext object of this focus-out event only if IME is
   // enabled by WebKit.
   if (is_enabled_) {
     // To reset the GtkIMContext object and prevent data loss.
     ConfirmComposition();
     gtk_im_context_focus_out(context_);
   }
 
   // To make sure it'll be in correct state when focused in again.
   gtk_im_context_reset(context_simple_);
   gtk_im_context_focus_out(context_simple_);
 
   is_composing_text_ = false;
 
   // Disable RenderWidget's IME related events to save bandwidth.
-  host_view_->GetRenderWidgetHost()->SetInputMethodActive(false);
+  if (host_view_->GetRenderWidgetHost())
+    host_view_->GetRenderWidgetHost()->SetInputMethodActive(false);
 }
 
 void GtkIMContextWrapper::AppendInputMethodsContextMenu(MenuGtk* menu) {
   std::string label = gtk_util::ConvertAcceleratorsFromWindowsStyle(
       l10n_util::GetStringUTF8(IDS_CONTENT_CONTEXT_INPUT_METHODS_MENU));
   GtkWidget* menuitem = gtk_menu_item_new_with_mnemonic(label.c_str());
   GtkWidget* submenu = gtk_menu_new();
   gtk_menu_item_set_submenu(GTK_MENU_ITEM(menuitem), submenu);
   gtk_im_multicontext_append_menuitems(GTK_IM_MULTICONTEXT(context_),
                                        GTK_MENU_SHELL(submenu));
@@ skipping 89 matching lines @@
   if (wke->text[0]) {
     wke->type = WebKit::WebInputEvent::Char;
     wke->skip_in_browser = true;
     host_view_->ForwardKeyboardEvent(*wke);
   }
 }
 
 void GtkIMContextWrapper::ProcessInputMethodResult(const GdkEventKey* event,
                                                    bool filtered) {
   RenderWidgetHost* host = host_view_->GetRenderWidgetHost();
+  if (!host)
+    return;
+
   bool committed = false;
   // We do commit before preedit change, so that we can optimize some
   // unnecessary preedit changes.
   if (commit_text_.length()) {
     if (filtered && NeedCommitByForwardingCharEvent()) {
       // Send a Char event when we input a composed character without IMEs
       // so that this event is to be dispatched to onkeypress() handlers,
       // autofill, etc.
       // Only commit text generated by a filtered key down event can be sent
       // as a Char event, because a unfiltered key down event will probably
@@ skipping 32 matching lines @@
   }
 }
 
 void GtkIMContextWrapper::ConfirmComposition() {
   if (!is_enabled_)
     return;
 
   DCHECK(!is_in_key_event_handler_);
 
   if (is_composing_text_) {
-    host_view_->GetRenderWidgetHost()->ImeConfirmComposition();
+    if (host_view_->GetRenderWidgetHost())
+      host_view_->GetRenderWidgetHost()->ImeConfirmComposition();
 
     // Reset the input method.
     CancelComposition();
   }
 }
 
 void GtkIMContextWrapper::HandleCommit(const string16& text) {
   // Append the text to the buffer, because commit signal might be fired
   // multiple times when processing a key event.
   commit_text_.append(text);
   // Nothing needs to do, if it's currently in ProcessKeyEvent()
   // handler, which will send commit text to webkit later. Otherwise,
   // we need send it here.
   // It's possible that commit signal is fired without a key event, for
   // example when user input via a voice or handwriting recognition software.
   // In this case, the text must be committed directly.
-  if (!is_in_key_event_handler_)
+  if (!is_in_key_event_handler_ && host_view_->GetRenderWidgetHost())
     host_view_->GetRenderWidgetHost()->ImeConfirmComposition(text);
 }
 
 void GtkIMContextWrapper::HandlePreeditStart() {
   is_composing_text_ = true;
 }
 
 void GtkIMContextWrapper::HandlePreeditChanged(const gchar* text,
                                                PangoAttrList* attrs,
                                                int cursor_position) {
@@ skipping 10 matching lines @@
                          &preedit_selection_end_);
 
   // In case we are using a buggy input method which doesn't fire
   // "preedit_start" signal.
   if (preedit_text_.length())
     is_composing_text_ = true;
 
   // Nothing needs to do, if it's currently in ProcessKeyEvent()
   // handler, which will send preedit text to webkit later.
   // Otherwise, we need send it here if it's been changed.
-  if (!is_in_key_event_handler_) {
+  if (!is_in_key_event_handler_ && host_view_->GetRenderWidgetHost()) {
     host_view_->GetRenderWidgetHost()->ImeSetComposition(
         preedit_text_, preedit_underlines_, preedit_selection_start_,
         preedit_selection_end_);
   }
 }
 
 void GtkIMContextWrapper::HandlePreeditEnd() {
-  bool changed = false;
   if (preedit_text_.length()) {
     // The composition session has been finished.
     preedit_text_.clear();
     preedit_underlines_.clear();
     is_preedit_changed_ = true;
-    changed = true;
+
+    // If there is still a preedit text when firing "preedit-end" signal,
+    // we need inform webkit to clear it.
+    // It's only necessary when it's not in ProcessKeyEvent ().
+    if (!is_in_key_event_handler_ && host_view_->GetRenderWidgetHost())
+      host_view_->GetRenderWidgetHost()->ImeCancelComposition();
   }
 
-  // If there is still a preedit text when firing "preedit-end" signal,
-  // we need inform webkit to clear it.
-  // It's only necessary when it's not in ProcessKeyEvent ().
-  if (!is_in_key_event_handler_ && changed)
-    host_view_->GetRenderWidgetHost()->ImeCancelComposition();
-
   // Don't set is_composing_text_ to false here, because "preedit_end"
   // signal may be fired before "commit" signal.
 }
 
 void GtkIMContextWrapper::HandleHostViewRealize(GtkWidget* widget) {
   // We should only set im context's client window once, because when setting
   // client window.im context may destroy and recreate its internal states and
   // objects.
   if (widget->window) {
     gtk_im_context_set_client_window(context_, widget->window);
@@ skipping 128 matching lines @@
     } while (pango_attr_iterator_next(iter));
     pango_attr_iterator_destroy(iter);
   }
 
   // Use a black thin underline by default.
   if (underlines->empty()) {
     underlines->push_back(
         WebKit::WebCompositionUnderline(0, length, SK_ColorBLACK, false));
   }
 }