Add proper const/non-const versions of CPDF_Dictionary::GetDictFor().

BUG=pdfium:234

Change-Id: I6fde00c976ad4bb9cab632f465cf292f5b1da3d2
Reviewed-on: https://pdfium-review.googlesource.com/32914
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>

7 files changed, 42 insertions, 22 deletions

diff --git a/core/fpdfapi/font/cpdf_font.cpp b/core/fpdfapi/font/cpdf_font.cpp
index cc867d69d9..0bba1057e7 100644
--- a/core/fpdfapi/font/cpdf_font.cpp
+++ b/core/fpdfapi/font/cpdf_font.cpp
@@ -324,7 +324,8 @@ std::unique_ptr<CPDF_Font> CPDF_Font::Create(CPDF_Document* pDoc,
     ByteString tag = pFontDict->GetStringFor("BaseFont").Left(4);
     for (size_t i = 0; i < FX_ArraySize(kChineseFontNames); ++i) {
       if (tag == ByteString(kChineseFontNames[i], 4)) {
-        CPDF_Dictionary* pFontDesc = pFontDict->GetDictFor("FontDescriptor");
+        const CPDF_Dictionary* pFontDesc =
+            pFontDict->GetDictFor("FontDescriptor");
         if (!pFontDesc || !pFontDesc->KeyExist("FontFile2"))
           pFont = pdfium::MakeUnique<CPDF_CIDFont>();
         break;
diff --git a/core/fpdfapi/page/cpdf_docpagedata.cpp b/core/fpdfapi/page/cpdf_docpagedata.cpp
index 92dca138cf..37283b9d64 100644
--- a/core/fpdfapi/page/cpdf_docpagedata.cpp
+++ b/core/fpdfapi/page/cpdf_docpagedata.cpp
@@ -241,7 +241,7 @@ CPDF_ColorSpace* CPDF_DocPageData::GetColorSpaceInternal(
     ByteString name = pCSObj->GetString();
     CPDF_ColorSpace* pCS = CPDF_ColorSpace::ColorspaceFromName(name);
     if (!pCS && pResources) {
-      CPDF_Dictionary* pList = pResources->GetDictFor("ColorSpace");
+      const CPDF_Dictionary* pList = pResources->GetDictFor("ColorSpace");
       if (pList) {
         return GetColorSpaceInternal(pList->GetDirectObjectFor(name), nullptr,
                                      pVisited, pVisitedInternal);
@@ -250,7 +250,7 @@ CPDF_ColorSpace* CPDF_DocPageData::GetColorSpaceInternal(
     if (!pCS || !pResources)
       return pCS;
 
-    CPDF_Dictionary* pColorSpaces = pResources->GetDictFor("ColorSpace");
+    const CPDF_Dictionary* pColorSpaces = pResources->GetDictFor("ColorSpace");
     if (!pColorSpaces)
       return pCS;
 
diff --git a/core/fpdfapi/parser/cpdf_dictionary.cpp b/core/fpdfapi/parser/cpdf_dictionary.cpp
index 1ede5e707a..5257a20586 100644
--- a/core/fpdfapi/parser/cpdf_dictionary.cpp
+++ b/core/fpdfapi/parser/cpdf_dictionary.cpp
@@ -130,7 +130,19 @@ bool CPDF_Dictionary::GetBooleanFor(const ByteString& key,
   return ToBoolean(p) ? p->GetInteger() != 0 : bDefault;
 }
 
-CPDF_Dictionary* CPDF_Dictionary::GetDictFor(const ByteString& key) const {
+const CPDF_Dictionary* CPDF_Dictionary::GetDictFor(
+    const ByteString& key) const {
+  CPDF_Object* p = GetDirectObjectFor(key);
+  if (!p)
+    return nullptr;
+  if (CPDF_Dictionary* pDict = p->AsDictionary())
+    return pDict;
+  if (CPDF_Stream* pStream = p->AsStream())
+    return pStream->GetDict();
+  return nullptr;
+}
+
+CPDF_Dictionary* CPDF_Dictionary::GetDictFor(const ByteString& key) {
   CPDF_Object* p = GetDirectObjectFor(key);
   if (!p)
     return nullptr;
diff --git a/core/fpdfapi/parser/cpdf_dictionary.h b/core/fpdfapi/parser/cpdf_dictionary.h
index df789aa7b4..5240ab3b5c 100644
--- a/core/fpdfapi/parser/cpdf_dictionary.h
+++ b/core/fpdfapi/parser/cpdf_dictionary.h
@@ -51,7 +51,8 @@ class CPDF_Dictionary : public CPDF_Object {
   int GetIntegerFor(const ByteString& key, int default_int) const;
   bool GetBooleanFor(const ByteString& key, bool bDefault = false) const;
   float GetNumberFor(const ByteString& key) const;
-  CPDF_Dictionary* GetDictFor(const ByteString& key) const;
+  const CPDF_Dictionary* GetDictFor(const ByteString& key) const;
+  CPDF_Dictionary* GetDictFor(const ByteString& key);
   const CPDF_Stream* GetStreamFor(const ByteString& key) const;
   CPDF_Stream* GetStreamFor(const ByteString& key);
   const CPDF_Array* GetArrayFor(const ByteString& key) const;
diff --git a/core/fpdfapi/parser/cpdf_document.cpp b/core/fpdfapi/parser/cpdf_document.cpp
index 5264d4e795..5479a06174 100644
--- a/core/fpdfapi/parser/cpdf_document.cpp
+++ b/core/fpdfapi/parser/cpdf_document.cpp
@@ -322,11 +322,16 @@ void CPDF_Document::ResetTraversal() {
   m_pTreeTraversal.clear();
 }
 
-CPDF_Dictionary* CPDF_Document::GetPagesDict() const {
+const CPDF_Dictionary* CPDF_Document::GetPagesDict() const {
   const CPDF_Dictionary* pRoot = GetRoot();
   return pRoot ? pRoot->GetDictFor("Pages") : nullptr;
 }
 
+CPDF_Dictionary* CPDF_Document::GetPagesDict() {
+  CPDF_Dictionary* pRoot = GetRoot();
+  return pRoot ? pRoot->GetDictFor("Pages") : nullptr;
+}
+
 bool CPDF_Document::IsPageLoaded(int iPage) const {
   return !!m_PageList[iPage];
 }
@@ -363,7 +368,7 @@ void CPDF_Document::SetPageObjNum(int iPage, uint32_t objNum) {
   m_PageList[iPage] = objNum;
 }
 
-int CPDF_Document::FindPageIndex(CPDF_Dictionary* pNode,
+int CPDF_Document::FindPageIndex(const CPDF_Dictionary* pNode,
                                  uint32_t* skip_count,
                                  uint32_t objnum,
                                  int* index,
@@ -379,7 +384,7 @@ int CPDF_Document::FindPageIndex(CPDF_Dictionary* pNode,
     return -1;
   }
 
-  CPDF_Array* pKidList = pNode->GetArrayFor("Kids");
+  const CPDF_Array* pKidList = pNode->GetArrayFor("Kids");
   if (!pKidList)
     return -1;
 
@@ -395,14 +400,14 @@ int CPDF_Document::FindPageIndex(CPDF_Dictionary* pNode,
 
   if (count && count == pKidList->GetCount()) {
     for (size_t i = 0; i < count; i++) {
-      CPDF_Reference* pKid = ToReference(pKidList->GetObjectAt(i));
+      const CPDF_Reference* pKid = ToReference(pKidList->GetObjectAt(i));
       if (pKid && pKid->GetRefObjNum() == objnum)
         return static_cast<int>(*index + i);
     }
   }
 
   for (size_t i = 0; i < pKidList->GetCount(); i++) {
-    CPDF_Dictionary* pKid = pKidList->GetDictAt(i);
+    const CPDF_Dictionary* pKid = pKidList->GetDictAt(i);
     if (!pKid || pKid == pNode)
       continue;
 
@@ -426,7 +431,7 @@ int CPDF_Document::GetPageIndex(uint32_t objnum) {
       bSkipped = true;
     }
   }
-  CPDF_Dictionary* pPages = GetPagesDict();
+  const CPDF_Dictionary* pPages = GetPagesDict();
   if (!pPages)
     return -1;
 
@@ -445,7 +450,7 @@ int CPDF_Document::GetPageCount() const {
   return pdfium::CollectionSize<int>(m_PageList);
 }
 
-int CPDF_Document::RetrievePageCount() const {
+int CPDF_Document::RetrievePageCount() {
   CPDF_Dictionary* pPages = GetPagesDict();
   if (!pPages)
     return 0;
@@ -576,7 +581,7 @@ bool CPDF_Document::InsertDeletePDFPage(CPDF_Dictionary* pPages,
 }
 
 bool CPDF_Document::InsertNewPage(int iPage, CPDF_Dictionary* pPageDict) {
-  const CPDF_Dictionary* pRoot = GetRoot();
+  CPDF_Dictionary* pRoot = GetRoot();
   CPDF_Dictionary* pPages = pRoot ? pRoot->GetDictFor("Pages") : nullptr;
   if (!pPages)
     return false;
diff --git a/core/fpdfapi/parser/cpdf_document.h b/core/fpdfapi/parser/cpdf_document.h
index b169175668..356d341302 100644
--- a/core/fpdfapi/parser/cpdf_document.h
+++ b/core/fpdfapi/parser/cpdf_document.h
@@ -115,10 +115,10 @@ class CPDF_Document : public CPDF_IndirectObjectHolder {
 
  protected:
   // Retrieve page count information by getting count value from the tree nodes
-  int RetrievePageCount() const;
+  int RetrievePageCount();
   // When this method is called, m_pTreeTraversal[level] exists.
   CPDF_Dictionary* TraversePDFPages(int iPage, int* nPagesToGo, size_t level);
-  int FindPageIndex(CPDF_Dictionary* pNode,
+  int FindPageIndex(const CPDF_Dictionary* pNode,
                     uint32_t* skip_count,
                     uint32_t objnum,
                     int* index,
@@ -126,7 +126,8 @@ class CPDF_Document : public CPDF_IndirectObjectHolder {
   std::unique_ptr<CPDF_Object> ParseIndirectObject(uint32_t objnum) override;
   void LoadDocInternal();
   size_t CalculateEncodingDict(int charset, CPDF_Dictionary* pBaseDict);
-  CPDF_Dictionary* GetPagesDict() const;
+  const CPDF_Dictionary* GetPagesDict() const;
+  CPDF_Dictionary* GetPagesDict();
   CPDF_Dictionary* ProcessbCJK(
       CPDF_Dictionary* pBaseDict,
       int charset,
diff --git a/core/fpdfapi/parser/cpdf_security_handler.cpp b/core/fpdfapi/parser/cpdf_security_handler.cpp
index 7eb5c42f72..eeba53ef34 100644
--- a/core/fpdfapi/parser/cpdf_security_handler.cpp
+++ b/core/fpdfapi/parser/cpdf_security_handler.cpp
@@ -130,17 +130,17 @@ static bool LoadCryptInfo(const CPDF_Dictionary* pEncryptDict,
   cipher = FXCIPHER_RC4;
   keylen = 0;
   if (Version >= 4) {
-    CPDF_Dictionary* pCryptFilters = pEncryptDict->GetDictFor("CF");
-    if (!pCryptFilters) {
+    const CPDF_Dictionary* pCryptFilters = pEncryptDict->GetDictFor("CF");
+    if (!pCryptFilters)
       return false;
-    }
+
     if (name == "Identity") {
       cipher = FXCIPHER_NONE;
     } else {
-      CPDF_Dictionary* pDefFilter = pCryptFilters->GetDictFor(name);
-      if (!pDefFilter) {
+      const CPDF_Dictionary* pDefFilter = pCryptFilters->GetDictFor(name);
+      if (!pDefFilter)
         return false;
-      }
+
       int nKeyBits = 0;
       if (Version == 4) {
         nKeyBits = pDefFilter->GetIntegerFor("Length", 0);