Watch for destruction of widget during callback

fpdfsdk/fsdk_baseform.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "fpdfsdk/include/fsdk_baseform.h"
 
 #include <algorithm>
 #include <map>
 #include <memory>
 #include <vector>
 
 #include "core/fpdfapi/fpdf_page/include/cpdf_page.h"
 #include "core/fpdfapi/fpdf_parser/include/cfdf_document.h"
 #include "core/fpdfapi/fpdf_parser/include/cpdf_array.h"
 #include "core/fpdfapi/fpdf_parser/include/cpdf_document.h"
 #include "core/fpdfapi/fpdf_parser/include/cpdf_stream.h"
 #include "core/fxge/include/fx_ge.h"
 #include "fpdfsdk/formfiller/cffl_formfiller.h"
 #include "fpdfsdk/fxedit/include/fxet_edit.h"
 #include "fpdfsdk/include/fsdk_actionhandler.h"
 #include "fpdfsdk/include/fsdk_baseannot.h"
 #include "fpdfsdk/include/fsdk_define.h"
 #include "fpdfsdk/include/fsdk_mgr.h"
 #include "fpdfsdk/javascript/ijs_context.h"
 #include "fpdfsdk/javascript/ijs_runtime.h"
 #include "fpdfsdk/pdfwindow/PWL_Utils.h"
+#include "third_party/base/stl_util.h"
 
 #ifdef PDF_ENABLE_XFA
 #include "fpdfsdk/fpdfxfa/include/fpdfxfa_doc.h"
 #include "fpdfsdk/fpdfxfa/include/fpdfxfa_util.h"
 #include "xfa/fxfa/include/cxfa_eventparam.h"
 #include "xfa/fxfa/include/xfa_ffdocview.h"
 #include "xfa/fxfa/include/xfa_ffwidget.h"
 #include "xfa/fxfa/include/xfa_ffwidgethandler.h"
 #endif  // PDF_ENABLE_XFA
 
 PDFSDK_FieldAction::PDFSDK_FieldAction()
     : bModifier(FALSE),
       bShift(FALSE),
       nCommitKey(0),
       bKeyDown(FALSE),
       nSelEnd(0),
       nSelStart(0),
       bWillCommit(FALSE),
       bFieldFull(FALSE),
       bRC(TRUE) {}
 
+CPDFSDK_Widget::Observer::Observer(CPDFSDK_Widget** pWatchedPtr)
+    : m_pWatchedPtr(pWatchedPtr) {
+  (*m_pWatchedPtr)->AddObserver(this);
+}
+
+CPDFSDK_Widget::Observer::~Observer() {
+  if (m_pWatchedPtr)
+    (*m_pWatchedPtr)->RemoveObserver(this);
+}
+
+void CPDFSDK_Widget::Observer::OnWidgetDestroyed() {
+  if (m_pWatchedPtr) {

[Lei Zhang, 2016/07/29 22:30:06]

Is this always true, or can OnWidgetDestroyed() get called multiple times?

[Tom Sepez, 2016/08/01 16:24:54]

Shouldn't happen. Will change to assert.

+    *m_pWatchedPtr = nullptr;
+    m_pWatchedPtr = nullptr;
+  }
+}
+
 CPDFSDK_Widget::CPDFSDK_Widget(CPDF_Annot* pAnnot,
                                CPDFSDK_PageView* pPageView,
                                CPDFSDK_InterForm* pInterForm)
     : CPDFSDK_BAAnnot(pAnnot, pPageView),
       m_pInterForm(pInterForm),
       m_nAppAge(0),
       m_nValueAge(0)
 #ifdef PDF_ENABLE_XFA
       ,
       m_hMixXFAWidget(nullptr),
       m_pWidgetHandler(nullptr)
 #endif  // PDF_ENABLE_XFA
 {
 }
 
-CPDFSDK_Widget::~CPDFSDK_Widget() {}
+CPDFSDK_Widget::~CPDFSDK_Widget() {
+  for (auto* pObserver : m_Observers)
+    pObserver->OnWidgetDestroyed();
+}
+
+void CPDFSDK_Widget::AddObserver(Observer* pObserver) {
+  ASSERT(!pdfium::ContainsKey(m_Observers, pObserver));

[Lei Zhang, 2016/07/29 22:30:05]

You can also just try inserting, and then ASSERT the return result to make sure
it was actually inserted. Ditto for erase() below.

[Tom Sepez, 2016/08/01 16:24:54]

Probably leads to unused variable warnings when asserts not enabled.

+  m_Observers.insert(pObserver);
+}
+
+void CPDFSDK_Widget::RemoveObserver(Observer* pObserver) {
+  ASSERT(pdfium::ContainsKey(m_Observers, pObserver));
+  m_Observers.erase(pObserver);
+}
 
 #ifdef PDF_ENABLE_XFA
 CXFA_FFWidget* CPDFSDK_Widget::GetMixXFAWidget() const {
   CPDFSDK_Document* pSDKDoc = m_pPageView->GetSDKDocument();
   CPDFXFA_Document* pDoc = pSDKDoc->GetXFADocument();
   if (pDoc->GetDocType() == DOCTYPE_STATIC_XFA) {
     if (!m_hMixXFAWidget) {
       if (CXFA_FFDocView* pDocView = pDoc->GetXFADocView()) {
         CFX_WideString sName;
         if (GetFieldType() == FIELDTYPE_RADIOBUTTON) {
@@ skipping 2751 matching lines @@
       break;
     }
   }
 }
 
 CFX_FloatRect CBA_AnnotIterator::GetAnnotRect(const CPDFSDK_Annot* pAnnot) {
   CFX_FloatRect rcAnnot;
   pAnnot->GetPDFAnnot()->GetRect(rcAnnot);
   return rcAnnot;
 }