Add proper const/non-const versions of CPDF_Object methods.

Instead of having const methods that return non-const pointers.

BUG=pdfium:234

Change-Id: I598e9b4f267f702e2e71001cfe3aa3c9e9d8c12f
Reviewed-on: https://pdfium-review.googlesource.com/32182
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>

16 files changed, 73 insertions, 36 deletions

diff --git a/core/fpdfapi/page/cpdf_colorspace.cpp b/core/fpdfapi/page/cpdf_colorspace.cpp
index aa664d4e0f..4f68329862 100644
--- a/core/fpdfapi/page/cpdf_colorspace.cpp
+++ b/core/fpdfapi/page/cpdf_colorspace.cpp
@@ -458,7 +458,7 @@ std::unique_ptr<CPDF_ColorSpace> CPDF_ColorSpace::Load(
     return pdfium::WrapUnique(ColorspaceFromName(pObj->GetString()));
 
   if (const CPDF_Stream* pStream = pObj->AsStream()) {
-    CPDF_Dictionary* pDict = pStream->GetDict();
+    const CPDF_Dictionary* pDict = pStream->GetDict();
     if (!pDict)
       return nullptr;
 
diff --git a/core/fpdfapi/page/cpdf_stitchfunc.cpp b/core/fpdfapi/page/cpdf_stitchfunc.cpp
index 2083a91623..042e090062 100644
--- a/core/fpdfapi/page/cpdf_stitchfunc.cpp
+++ b/core/fpdfapi/page/cpdf_stitchfunc.cpp
@@ -27,7 +27,7 @@ bool CPDF_StitchFunc::v_Init(const CPDF_Object* pObj,
   if (m_nInputs != kRequiredNumInputs)
     return false;
 
-  CPDF_Dictionary* pDict = pObj->GetDict();
+  const CPDF_Dictionary* pDict = pObj->GetDict();
   if (!pDict)
     return false;
 
diff --git a/core/fpdfapi/parser/cpdf_array.cpp b/core/fpdfapi/parser/cpdf_array.cpp
index 5a5cdc9be0..9293101b32 100644
--- a/core/fpdfapi/parser/cpdf_array.cpp
+++ b/core/fpdfapi/parser/cpdf_array.cpp
@@ -66,7 +66,7 @@ std::unique_ptr<CPDF_Object> CPDF_Array::CloneNonCyclic(
   return std::move(pCopy);
 }
 
-CFX_FloatRect CPDF_Array::GetRect() {
+CFX_FloatRect CPDF_Array::GetRect() const {
   CFX_FloatRect rect;
   if (!IsArray() || m_Objects.size() != 4)
     return rect;
@@ -78,7 +78,7 @@ CFX_FloatRect CPDF_Array::GetRect() {
   return rect;
 }
 
-CFX_Matrix CPDF_Array::GetMatrix() {
+CFX_Matrix CPDF_Array::GetMatrix() const {
   CFX_Matrix matrix;
   if (!IsArray() || m_Objects.size() != 6)
     return CFX_Matrix();
diff --git a/core/fpdfapi/parser/cpdf_array.h b/core/fpdfapi/parser/cpdf_array.h
index bf8cb426c4..442b85cc80 100644
--- a/core/fpdfapi/parser/cpdf_array.h
+++ b/core/fpdfapi/parser/cpdf_array.h
@@ -47,8 +47,8 @@ class CPDF_Array : public CPDF_Object {
   CPDF_Stream* GetStreamAt(size_t index) const;
   CPDF_Array* GetArrayAt(size_t index) const;
   float GetFloatAt(size_t index) const { return GetNumberAt(index); }
-  CFX_Matrix GetMatrix();
-  CFX_FloatRect GetRect();
+  CFX_Matrix GetMatrix() const;
+  CFX_FloatRect GetRect() const;
 
   // Takes ownership of |pObj|, returns unowned pointer to it.
   CPDF_Object* Add(std::unique_ptr<CPDF_Object> pObj);
diff --git a/core/fpdfapi/parser/cpdf_dictionary.cpp b/core/fpdfapi/parser/cpdf_dictionary.cpp
index b3195b58af..29571d6c51 100644
--- a/core/fpdfapi/parser/cpdf_dictionary.cpp
+++ b/core/fpdfapi/parser/cpdf_dictionary.cpp
@@ -42,10 +42,12 @@ CPDF_Object::Type CPDF_Dictionary::GetType() const {
   return DICTIONARY;
 }
 
-CPDF_Dictionary* CPDF_Dictionary::GetDict() const {
-  // The method should be made non-const if we want to not be const.
-  // See bug #234.
-  return const_cast<CPDF_Dictionary*>(this);
+CPDF_Dictionary* CPDF_Dictionary::GetDict() {
+  return this;
+}
+
+const CPDF_Dictionary* CPDF_Dictionary::GetDict() const {
+  return this;
 }
 
 bool CPDF_Dictionary::IsDictionary() const {
diff --git a/core/fpdfapi/parser/cpdf_dictionary.h b/core/fpdfapi/parser/cpdf_dictionary.h
index 688e88e510..8ecbe2d6fc 100644
--- a/core/fpdfapi/parser/cpdf_dictionary.h
+++ b/core/fpdfapi/parser/cpdf_dictionary.h
@@ -33,7 +33,8 @@ class CPDF_Dictionary : public CPDF_Object {
   // CPDF_Object:
   Type GetType() const override;
   std::unique_ptr<CPDF_Object> Clone() const override;
-  CPDF_Dictionary* GetDict() const override;
+  CPDF_Dictionary* GetDict() override;
+  const CPDF_Dictionary* GetDict() const override;
   bool IsDictionary() const override;
   CPDF_Dictionary* AsDictionary() override;
   const CPDF_Dictionary* AsDictionary() const override;
diff --git a/core/fpdfapi/parser/cpdf_object.cpp b/core/fpdfapi/parser/cpdf_object.cpp
index 67632a040c..8190d3429f 100644
--- a/core/fpdfapi/parser/cpdf_object.cpp
+++ b/core/fpdfapi/parser/cpdf_object.cpp
@@ -19,8 +19,12 @@
 
 CPDF_Object::~CPDF_Object() {}
 
-CPDF_Object* CPDF_Object::GetDirect() const {
-  return const_cast<CPDF_Object*>(this);
+CPDF_Object* CPDF_Object::GetDirect() {
+  return this;
+}
+
+const CPDF_Object* CPDF_Object::GetDirect() const {
+  return this;
 }
 
 std::unique_ptr<CPDF_Object> CPDF_Object::CloneObjectNonCyclic(
@@ -55,7 +59,11 @@ int CPDF_Object::GetInteger() const {
   return 0;
 }
 
-CPDF_Dictionary* CPDF_Object::GetDict() const {
+CPDF_Dictionary* CPDF_Object::GetDict() {
+  return nullptr;
+}
+
+const CPDF_Dictionary* CPDF_Object::GetDict() const {
   return nullptr;
 }
 
diff --git a/core/fpdfapi/parser/cpdf_object.h b/core/fpdfapi/parser/cpdf_object.h
index 7a14492d70..21eec62b0d 100644
--- a/core/fpdfapi/parser/cpdf_object.h
+++ b/core/fpdfapi/parser/cpdf_object.h
@@ -56,12 +56,14 @@ class CPDF_Object {
   // copied to the object it points to directly.
   virtual std::unique_ptr<CPDF_Object> CloneDirectObject() const;
 
-  virtual CPDF_Object* GetDirect() const;
+  virtual CPDF_Object* GetDirect();
+  virtual const CPDF_Object* GetDirect() const;
   virtual ByteString GetString() const;
   virtual WideString GetUnicodeText() const;
   virtual float GetNumber() const;
   virtual int GetInteger() const;
-  virtual CPDF_Dictionary* GetDict() const;
+  virtual CPDF_Dictionary* GetDict();
+  virtual const CPDF_Dictionary* GetDict() const;
 
   virtual void SetString(const ByteString& str);
 
diff --git a/core/fpdfapi/parser/cpdf_reference.cpp b/core/fpdfapi/parser/cpdf_reference.cpp
index 2ca0bddc4f..3f45a96c6b 100644
--- a/core/fpdfapi/parser/cpdf_reference.cpp
+++ b/core/fpdfapi/parser/cpdf_reference.cpp
@@ -21,25 +21,30 @@ CPDF_Object::Type CPDF_Reference::GetType() const {
 }
 
 ByteString CPDF_Reference::GetString() const {
-  CPDF_Object* obj = SafeGetDirect();
+  const CPDF_Object* obj = SafeGetDirect();
   return obj ? obj->GetString() : ByteString();
 }
 
 float CPDF_Reference::GetNumber() const {
-  CPDF_Object* obj = SafeGetDirect();
+  const CPDF_Object* obj = SafeGetDirect();
   return obj ? obj->GetNumber() : 0;
 }
 
 int CPDF_Reference::GetInteger() const {
-  CPDF_Object* obj = SafeGetDirect();
+  const CPDF_Object* obj = SafeGetDirect();
   return obj ? obj->GetInteger() : 0;
 }
 
-CPDF_Dictionary* CPDF_Reference::GetDict() const {
+CPDF_Dictionary* CPDF_Reference::GetDict() {
   CPDF_Object* obj = SafeGetDirect();
   return obj ? obj->GetDict() : nullptr;
 }
 
+const CPDF_Dictionary* CPDF_Reference::GetDict() const {
+  const CPDF_Object* obj = SafeGetDirect();
+  return obj ? obj->GetDict() : nullptr;
+}
+
 bool CPDF_Reference::IsReference() const {
   return true;
 }
@@ -69,17 +74,27 @@ std::unique_ptr<CPDF_Object> CPDF_Reference::CloneNonCyclic(
   return pdfium::MakeUnique<CPDF_Reference>(m_pObjList.Get(), m_RefObjNum);
 }
 
-CPDF_Object* CPDF_Reference::SafeGetDirect() const {
+CPDF_Object* CPDF_Reference::SafeGetDirect() {
   CPDF_Object* obj = GetDirect();
   return (obj && !obj->IsReference()) ? obj : nullptr;
 }
 
+const CPDF_Object* CPDF_Reference::SafeGetDirect() const {
+  const CPDF_Object* obj = GetDirect();
+  return (obj && !obj->IsReference()) ? obj : nullptr;
+}
+
 void CPDF_Reference::SetRef(CPDF_IndirectObjectHolder* pDoc, uint32_t objnum) {
   m_pObjList = pDoc;
   m_RefObjNum = objnum;
 }
 
-CPDF_Object* CPDF_Reference::GetDirect() const {
+CPDF_Object* CPDF_Reference::GetDirect() {
+  return m_pObjList ? m_pObjList->GetOrParseIndirectObject(m_RefObjNum)
+                    : nullptr;
+}
+
+const CPDF_Object* CPDF_Reference::GetDirect() const {
   return m_pObjList ? m_pObjList->GetOrParseIndirectObject(m_RefObjNum)
                     : nullptr;
 }
diff --git a/core/fpdfapi/parser/cpdf_reference.h b/core/fpdfapi/parser/cpdf_reference.h
index b472b4a3ac..4cfb5c26e3 100644
--- a/core/fpdfapi/parser/cpdf_reference.h
+++ b/core/fpdfapi/parser/cpdf_reference.h
@@ -23,11 +23,13 @@ class CPDF_Reference : public CPDF_Object {
   // CPDF_Object:
   Type GetType() const override;
   std::unique_ptr<CPDF_Object> Clone() const override;
-  CPDF_Object* GetDirect() const override;
+  CPDF_Object* GetDirect() override;
+  const CPDF_Object* GetDirect() const override;
   ByteString GetString() const override;
   float GetNumber() const override;
   int GetInteger() const override;
-  CPDF_Dictionary* GetDict() const override;
+  CPDF_Dictionary* GetDict() override;
+  const CPDF_Dictionary* GetDict() const override;
   bool IsReference() const override;
   CPDF_Reference* AsReference() override;
   const CPDF_Reference* AsReference() const override;
@@ -41,7 +43,8 @@ class CPDF_Reference : public CPDF_Object {
   std::unique_ptr<CPDF_Object> CloneNonCyclic(
       bool bDirect,
       std::set<const CPDF_Object*>* pVisited) const override;
-  CPDF_Object* SafeGetDirect() const;
+  CPDF_Object* SafeGetDirect();
+  const CPDF_Object* SafeGetDirect() const;
 
   UnownedPtr<CPDF_IndirectObjectHolder> m_pObjList;
   uint32_t m_RefObjNum;
diff --git a/core/fpdfapi/parser/cpdf_stream.cpp b/core/fpdfapi/parser/cpdf_stream.cpp
index 45d2ebb30d..fdbe308878 100644
--- a/core/fpdfapi/parser/cpdf_stream.cpp
+++ b/core/fpdfapi/parser/cpdf_stream.cpp
@@ -37,7 +37,11 @@ CPDF_Object::Type CPDF_Stream::GetType() const {
   return STREAM;
 }
 
-CPDF_Dictionary* CPDF_Stream::GetDict() const {
+CPDF_Dictionary* CPDF_Stream::GetDict() {
+  return m_pDict.get();
+}
+
+const CPDF_Dictionary* CPDF_Stream::GetDict() const {
   return m_pDict.get();
 }
 
@@ -84,11 +88,12 @@ std::unique_ptr<CPDF_Object> CPDF_Stream::CloneNonCyclic(
   pAcc->LoadAllDataRaw();
 
   uint32_t streamSize = pAcc->GetSize();
-  CPDF_Dictionary* pDict = GetDict();
+  const CPDF_Dictionary* pDict = GetDict();
   std::unique_ptr<CPDF_Dictionary> pNewDict;
   if (pDict && !pdfium::ContainsKey(*pVisited, pDict)) {
-    pNewDict = ToDictionary(
-        static_cast<CPDF_Object*>(pDict)->CloneNonCyclic(bDirect, pVisited));
+    pNewDict =
+        ToDictionary(static_cast<const CPDF_Object*>(pDict)->CloneNonCyclic(
+            bDirect, pVisited));
   }
   return pdfium::MakeUnique<CPDF_Stream>(pAcc->DetachData(), streamSize,
                                          std::move(pNewDict));
diff --git a/core/fpdfapi/parser/cpdf_stream.h b/core/fpdfapi/parser/cpdf_stream.h
index f8b09af7e2..cc3dcac227 100644
--- a/core/fpdfapi/parser/cpdf_stream.h
+++ b/core/fpdfapi/parser/cpdf_stream.h
@@ -19,7 +19,6 @@ class CPDF_Stream : public CPDF_Object {
  public:
   CPDF_Stream();
 
-  // Takes ownership of |pData|.
   CPDF_Stream(std::unique_ptr<uint8_t, FxFreeDeleter> pData,
               uint32_t size,
               std::unique_ptr<CPDF_Dictionary> pDict);
@@ -29,7 +28,8 @@ class CPDF_Stream : public CPDF_Object {
   // CPDF_Object:
   Type GetType() const override;
   std::unique_ptr<CPDF_Object> Clone() const override;
-  CPDF_Dictionary* GetDict() const override;
+  CPDF_Dictionary* GetDict() override;
+  const CPDF_Dictionary* GetDict() const override;
   WideString GetUnicodeText() const override;
   bool IsStream() const override;
   CPDF_Stream* AsStream() override;
diff --git a/core/fpdfapi/parser/cpdf_stream_acc.cpp b/core/fpdfapi/parser/cpdf_stream_acc.cpp
index 9cce894fff..9cf9a1f464 100644
--- a/core/fpdfapi/parser/cpdf_stream_acc.cpp
+++ b/core/fpdfapi/parser/cpdf_stream_acc.cpp
@@ -64,7 +64,7 @@ void CPDF_StreamAcc::LoadAllDataRaw() {
   LoadAllData(true, 0, false);
 }
 
-CPDF_Dictionary* CPDF_StreamAcc::GetDict() const {
+const CPDF_Dictionary* CPDF_StreamAcc::GetDict() const {
   return m_pStream ? m_pStream->GetDict() : nullptr;
 }
 
diff --git a/core/fpdfapi/parser/cpdf_stream_acc.h b/core/fpdfapi/parser/cpdf_stream_acc.h
index 89a454a0f0..1c9d5ef096 100644
--- a/core/fpdfapi/parser/cpdf_stream_acc.h
+++ b/core/fpdfapi/parser/cpdf_stream_acc.h
@@ -29,7 +29,7 @@ class CPDF_StreamAcc : public Retainable {
   void LoadAllDataRaw();
 
   const CPDF_Stream* GetStream() const { return m_pStream.Get(); }
-  CPDF_Dictionary* GetDict() const;
+  const CPDF_Dictionary* GetDict() const;
 
   uint8_t* GetData() const;
   uint32_t GetSize() const;
diff --git a/fpdfsdk/cpdfsdk_helpers.cpp b/fpdfsdk/cpdfsdk_helpers.cpp
index 1b90497456..5498909c32 100644
--- a/fpdfsdk/cpdfsdk_helpers.cpp
+++ b/fpdfsdk/cpdfsdk_helpers.cpp
@@ -330,8 +330,9 @@ unsigned long DecodeStreamMaybeCopyAndReturnLength(const CPDF_Stream* stream,
   ASSERT(stream);
   uint8_t* data = stream->GetRawData();
   uint32_t len = stream->GetRawSize();
-  CPDF_Dictionary* dict = stream->GetDict();
-  CPDF_Object* decoder = dict ? dict->GetDirectObjectFor("Filter") : nullptr;
+  const CPDF_Dictionary* dict = stream->GetDict();
+  const CPDF_Object* decoder =
+      dict ? dict->GetDirectObjectFor("Filter") : nullptr;
   if (decoder && (decoder->IsArray() || decoder->IsName())) {
     // Decode the stream if one or more stream filters are specified.
     uint8_t* decoded_data = nullptr;
diff --git a/fpdfsdk/fpdf_ppo.cpp b/fpdfsdk/fpdf_ppo.cpp
index c3b6402a97..bf8ed25af0 100644
--- a/fpdfsdk/fpdf_ppo.cpp
+++ b/fpdfsdk/fpdf_ppo.cpp
@@ -168,7 +168,7 @@ const CPDF_Object* PageDictGetInheritableTag(const CPDF_Dictionary* pDict,
 CFX_FloatRect GetMediaBox(const CPDF_Dictionary* pPageDict) {
   const CPDF_Object* pMediaBox =
       PageDictGetInheritableTag(pPageDict, "MediaBox");
-  CPDF_Array* pArray = ToArray(pMediaBox->GetDirect());
+  const CPDF_Array* pArray = ToArray(pMediaBox->GetDirect());
   if (!pArray)
     return CFX_FloatRect();
   return pArray->GetRect();