Adjust the order of clearing resource in CPDF_DocPageData::Clear

core/src/fpdfapi/fpdf_page/fpdf_page_doc.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 "../../../include/fpdfapi/fpdf_page.h"
 #include "../../../include/fpdfapi/fpdf_module.h"
 #include "../../../include/fdrm/fx_crypt.h"
 #include "../fpdf_font/font_int.h"
@@ skipping 133 matching lines @@
     m_FontFileMap.InitHashTable(32);
 }
 CPDF_DocPageData::~CPDF_DocPageData()
 {
     Clear(FALSE);
     Clear(TRUE);
 }
 void CPDF_DocPageData::Clear(FX_BOOL bForceRelease)
 {
     FX_POSITION pos;
     FX_DWORD    nCount;

[Tom Sepez, 2014/09/19 17:40:38]

In fact, we can remove the nCount local entirely, since it isn't adding any
value beyond directly using the left-hand-side of whatever you set it to.

 
     m_bForceClear = bForceRelease;
     pos = m_FontMap.GetStartPosition();

[Tom Sepez, 2014/09/19 17:36:31]

Nit: need a small comment here explaining that compound objects need to be
deleted before simple ones or some such.

     while (pos) {
         CPDF_Dictionary* fontDict;
         CPDF_CountedObject<CPDF_Font*>* fontData;
         m_FontMap.GetNextAssoc(pos, fontDict, fontData);
         nCount = fontData->m_nCount;
         if (bForceRelease || nCount < 2) {
             delete fontData->m_Obj;
             fontData->m_Obj = NULL;
         }
     }
-    pos = m_ImageMap.GetStartPosition();
-    while (pos) {
-        FX_DWORD objNum;
-        CPDF_CountedObject<CPDF_Image*>* imageData;
-        m_ImageMap.GetNextAssoc(pos, objNum, imageData);
-        nCount = imageData->m_nCount;
-        if (bForceRelease || nCount < 2) {
-            delete imageData->m_Obj;
-            delete imageData;
-            m_ImageMap.RemoveKey(objNum);
-        }
-    }
     pos = m_ColorSpaceMap.GetStartPosition();
     while (pos) {
         CPDF_Object* csKey;
         CPDF_CountedObject<CPDF_ColorSpace*>* csData;
         m_ColorSpaceMap.GetNextAssoc(pos, csKey, csData);
         nCount = csData->m_nCount;
         if (bForceRelease || nCount < 2) {
             csData->m_Obj->ReleaseCS();
             csData->m_Obj = NULL;
         }
@@ skipping 30 matching lines @@
             delete ftData->m_Obj;
             delete ftData;
             m_FontFileMap.RemoveKey(ftKey);
         }
     }
     pos = m_PatternMap.GetStartPosition();
     while (pos) {
         CPDF_Object* ptObj;
         CPDF_CountedObject<CPDF_Pattern*>* ptData;
         m_PatternMap.GetNextAssoc(pos, ptObj, ptData);
         nCount = ptData->m_nCount;

[Tom Sepez, 2014/09/19 17:36:31]

nit: if ptObj->m_obj is NULL, we can short-circuit execution here with a
"continue" before even considering m_nCount. And you may not need the local
m_nCount since its only used once (in the if below) and ptData->m_nCount is just
fine to use there. I think the loop reads clearer that way.

         if (bForceRelease || nCount < 2) {
-            ptData->m_Obj->SetForceClear(bForceRelease);
-            delete ptData->m_Obj;
-            ptData->m_Obj = NULL;
+            if (ptData->m_Obj) {
+                ptData->m_Obj->SetForceClear(bForceRelease);
+                delete ptData->m_Obj;
+                ptData->m_Obj = NULL;
+            }
+        }
+    }
+    pos = m_ImageMap.GetStartPosition();
+    while (pos) {
+        FX_DWORD objNum;
+        CPDF_CountedObject<CPDF_Image*>* imageData;
+        m_ImageMap.GetNextAssoc(pos, objNum, imageData);
+        nCount = imageData->m_nCount;
+        if (bForceRelease || nCount < 2) {
+            delete imageData->m_Obj;

[Tom Sepez, 2014/09/19 17:36:31]

do we need to check imageData->m_obj for NULLness here too?

+            delete imageData;
+            m_ImageMap.RemoveKey(objNum);
         }
     }
 }
 CPDF_Font* CPDF_DocPageData::GetFont(CPDF_Dictionary* pFontDict, FX_BOOL findOnly)
 {
     if (!pFontDict) {
         return NULL;
     }
     if (findOnly) {
         CPDF_CountedObject<CPDF_Font*>* fontData;
@@ skipping 384 matching lines @@
     m_FontFileMap.SetAt(pFontStream, ftData);
     return pFontFile;
 }
 void CPDF_DocPageData::ReleaseFontFileStreamAcc(CPDF_Stream* pFontStream, FX_BOOL bForce)
 {
     if (!pFontStream) {
         return;
     }
     PDF_DocPageData_Release<CPDF_Stream*, CPDF_StreamAcc*>(m_FontFileMap, pFontStream, NULL, bForce);
 }