[Merge to XFA] Revert "Revert "Add type cast definitions for CPDF_Dictionary.""

This reverts commit 937840e1722d1f2b77d80575d6e710d760662c9c.

Add type cast definitions for CPDF_Dictionary.

This CL adds ToCPDFDictionary type definitions and updates one file to use
instead of straight casts. I had to fix two places where we'd casted off the
constness of the original pointer.

BUG=pdfium:201
R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/1420583003 .

(cherry picked from commit 39869b641511c882d78e17548293cdb458c36f38)

Review URL: https://codereview.chromium.org/1410343003 .

6 files changed, 58 insertions, 56 deletions

diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_decode.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_decode.cpp
index 2d6e9f3436..55c62e2878 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_decode.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_decode.cpp
@@ -283,7 +283,7 @@ ICodec_ScanlineDecoder* FPDFAPI_CreateFlateDecoder(
   int predictor = 0;
   int Colors = 0, BitsPerComponent = 0, Columns = 0;
   if (pParams) {
-    predictor = ((CPDF_Dictionary*)pParams)->GetInteger(FX_BSTRC("Predictor"));
+    predictor = pParams->GetInteger(FX_BSTRC("Predictor"));
     Colors = pParams->GetInteger(FX_BSTRC("Colors"), 1);
     BitsPerComponent = pParams->GetInteger(FX_BSTRC("BitsPerComponent"), 8);
     Columns = pParams->GetInteger(FX_BSTRC("Columns"), 1);
@@ -306,9 +306,8 @@ FX_DWORD FPDFAPI_FlateOrLZWDecode(FX_BOOL bLZW,
   FX_BOOL bEarlyChange = TRUE;
   int Colors = 0, BitsPerComponent = 0, Columns = 0;
   if (pParams) {
-    predictor = ((CPDF_Dictionary*)pParams)->GetInteger(FX_BSTRC("Predictor"));
-    bEarlyChange =
-        ((CPDF_Dictionary*)pParams)->GetInteger(FX_BSTRC("EarlyChange"), 1);
+    predictor = pParams->GetInteger(FX_BSTRC("Predictor"));
+    bEarlyChange = pParams->GetInteger(FX_BSTRC("EarlyChange"), 1);
     Colors = pParams->GetInteger(FX_BSTRC("Colors"), 1);
     BitsPerComponent = pParams->GetInteger(FX_BSTRC("BitsPerComponent"), 8);
     Columns = pParams->GetInteger(FX_BSTRC("Columns"), 1);
@@ -365,7 +364,9 @@ FX_BOOL PDF_DataDecode(const uint8_t* src_buf,
     int estimated_size =
         i == DecoderList.GetSize() - 1 ? last_estimated_size : 0;
     CFX_ByteString decoder = DecoderList[i];
-    CPDF_Dictionary* pParam = (CPDF_Dictionary*)ParamList[i];
+    // Use ToDictionary here because we can push NULL into the ParamList.
+    CPDF_Dictionary* pParam =
+        ToDictionary(static_cast<CPDF_Object*>(ParamList[i]));
     uint8_t* new_buf = NULL;
     FX_DWORD new_size = (FX_DWORD)-1;
     int offset = -1;
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp
index 5b78013694..7f7f3d195f 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp
@@ -142,18 +142,15 @@ CPDF_Dictionary* CPDF_Document::GetPage(int iPage) {
     return nullptr;
 
   if (m_bLinearized && (iPage == (int)m_dwFirstPageNo)) {
-    CPDF_Object* pObj = GetIndirectObject(m_dwFirstPageObjNum);
-    if (pObj && pObj->GetType() == PDFOBJ_DICTIONARY) {
-      return static_cast<CPDF_Dictionary*>(pObj);
-    }
+    if (CPDF_Dictionary* pDict =
+            ToDictionary(GetIndirectObject(m_dwFirstPageObjNum)))
+      return pDict;
   }
 
   int objnum = m_PageList.GetAt(iPage);
   if (objnum) {
-    CPDF_Object* pObj = GetIndirectObject(objnum);
-    if (pObj && pObj->GetType() == PDFOBJ_DICTIONARY) {
-      return static_cast<CPDF_Dictionary*>(pObj);
-    }
+    if (CPDF_Dictionary* pDict = ToDictionary(GetIndirectObject(objnum)))
+      return pDict;
   }
 
   CPDF_Dictionary* pRoot = GetRoot();
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_fdf.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_fdf.cpp
index 19359ad7cf..82bfbb56eb 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_fdf.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_fdf.cpp
@@ -70,13 +70,11 @@ void CFDF_Document::ParseStream(IFX_FileRead* pFile, FX_BOOL bOwnFile) {
       if (word != FX_BSTRC("trailer")) {
         break;
       }
-      CPDF_Dictionary* pMainDict =
-          (CPDF_Dictionary*)parser.GetObject(this, 0, 0, 0);
-      if (pMainDict == NULL || pMainDict->GetType() != PDFOBJ_DICTIONARY) {
-        break;
+      if (CPDF_Dictionary* pMainDict =
+              ToDictionary(parser.GetObject(this, 0, 0, 0))) {
+        m_pRootDict = pMainDict->GetDict(FX_BSTRC("Root"));
+        pMainDict->Release();
       }
-      m_pRootDict = pMainDict->GetDict(FX_BSTRC("Root"));
-      pMainDict->Release();
       break;
     }
   }
@@ -142,18 +140,17 @@ void FPDF_FileSpec_SetWin32Path(CPDF_Object* pFileSpec,
   }
   if (pFileSpec->GetType() == PDFOBJ_STRING) {
     pFileSpec->SetString(CFX_ByteString::FromUnicode(result));
-  } else if (pFileSpec->GetType() == PDFOBJ_DICTIONARY) {
-    ((CPDF_Dictionary*)pFileSpec)
-        ->SetAtString(FX_BSTRC("F"), CFX_ByteString::FromUnicode(result));
-    ((CPDF_Dictionary*)pFileSpec)
-        ->SetAtString(FX_BSTRC("UF"), PDF_EncodeText(result));
-    ((CPDF_Dictionary*)pFileSpec)->RemoveAt(FX_BSTRC("FS"));
+  } else if (CPDF_Dictionary* pFileDict = pFileSpec->AsDictionary()) {
+    pFileDict->SetAtString(FX_BSTRC("F"), CFX_ByteString::FromUnicode(result));
+    pFileDict->SetAtString(FX_BSTRC("UF"), PDF_EncodeText(result));
+    pFileDict->RemoveAt(FX_BSTRC("FS"));
   }
 }
 CFX_WideString FPDF_FileSpec_GetWin32Path(const CPDF_Object* pFileSpec) {
   CFX_WideString wsFileName;
-  if (pFileSpec->GetType() == PDFOBJ_DICTIONARY) {
-    CPDF_Dictionary* pDict = (CPDF_Dictionary*)pFileSpec;
+  if (!pFileSpec) {
+    wsFileName = CFX_WideString();
+  } else if (const CPDF_Dictionary* pDict = pFileSpec->AsDictionary()) {
     wsFileName = pDict->GetUnicodeText(FX_BSTRC("UF"));
     if (wsFileName.IsEmpty()) {
       wsFileName = CFX_WideString::FromLocal(pDict->GetString(FX_BSTRC("F")));
@@ -164,9 +161,7 @@ CFX_WideString FPDF_FileSpec_GetWin32Path(const CPDF_Object* pFileSpec) {
     if (wsFileName.IsEmpty() && pDict->KeyExist(FX_BSTRC("DOS"))) {
       wsFileName = CFX_WideString::FromLocal(pDict->GetString(FX_BSTRC("DOS")));
     }
-  } else if (!pFileSpec)
-    wsFileName = CFX_WideString();
-  else {
+  } else {
     wsFileName = CFX_WideString::FromLocal(pFileSpec->GetString());
   }
   if (wsFileName[0] != '/') {
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp
index 79a2bcde8a..55c274ac0f 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp
@@ -28,7 +28,7 @@ void CPDF_Object::Destroy() {
       delete (CPDF_Array*)this;
       break;
     case PDFOBJ_DICTIONARY:
-      delete (CPDF_Dictionary*)this;
+      delete this->AsDictionary();
       break;
     case PDFOBJ_STREAM:
       delete (CPDF_Stream*)this;
@@ -138,7 +138,9 @@ int CPDF_Object::GetInteger() const {
 CPDF_Dictionary* CPDF_Object::GetDict() const {
   switch (m_Type) {
     case PDFOBJ_DICTIONARY:
-      return (CPDF_Dictionary*)this;
+      // The method should be made non-const if we want to not be const.
+      // See bug #234.
+      return const_cast<CPDF_Dictionary*>(this->AsDictionary());
     case PDFOBJ_STREAM:
       return ((CPDF_Stream*)this)->GetDict();
     case PDFOBJ_REFERENCE: {
@@ -215,7 +217,7 @@ FX_BOOL CPDF_Object::IsIdentical(CPDF_Object* pOther) const {
     case PDFOBJ_ARRAY:
       return (((CPDF_Array*)this)->Identical((CPDF_Array*)pOther));
     case PDFOBJ_DICTIONARY:
-      return (((CPDF_Dictionary*)this)->Identical((CPDF_Dictionary*)pOther));
+      return this->AsDictionary()->Identical(pOther->AsDictionary());
     case PDFOBJ_NULL:
       return TRUE;
     case PDFOBJ_STREAM:
@@ -264,7 +266,7 @@ CPDF_Object* CPDF_Object::CloneInternal(FX_BOOL bDirect,
     }
     case PDFOBJ_DICTIONARY: {
       CPDF_Dictionary* pCopy = new CPDF_Dictionary();
-      CPDF_Dictionary* pThis = (CPDF_Dictionary*)this;
+      const CPDF_Dictionary* pThis = this->AsDictionary();
       FX_POSITION pos = pThis->m_Map.GetStartPosition();
       while (pos) {
         CFX_ByteString key;
@@ -283,9 +285,9 @@ CPDF_Object* CPDF_Object::CloneInternal(FX_BOOL bDirect,
       acc.LoadAllData(pThis, TRUE);
       FX_DWORD streamSize = acc.GetSize();
       CPDF_Dictionary* pDict = pThis->GetDict();
-      if (pDict)
-        pDict = (CPDF_Dictionary*)((CPDF_Object*)pDict)
-                    ->CloneInternal(bDirect, visited);
+      if (pDict) {
+        pDict = ToDictionary(pDict->CloneInternal(bDirect, visited));
+      }
       return new CPDF_Stream(acc.DetachData(), streamSize, pDict);
     }
     case PDFOBJ_REFERENCE: {
@@ -335,6 +337,14 @@ void CPDF_Object::SetUnicodeText(const FX_WCHAR* pUnicodes, int len) {
   }
 }
 
+CPDF_Dictionary* CPDF_Object::AsDictionary() {
+  return IsDictionary() ? static_cast<CPDF_Dictionary*>(this) : nullptr;
+}
+
+const CPDF_Dictionary* CPDF_Object::AsDictionary() const {
+  return IsDictionary() ? static_cast<const CPDF_Dictionary*>(this) : nullptr;
+}
+
 CPDF_Number::CPDF_Number(int value)
     : CPDF_Object(PDFOBJ_NUMBER), m_bInteger(TRUE), m_Integer(value) {}
 
@@ -442,8 +452,8 @@ CPDF_Dictionary* CPDF_Array::GetDict(FX_DWORD i) const {
   if (!p) {
     return NULL;
   }
-  if (p->GetType() == PDFOBJ_DICTIONARY) {
-    return (CPDF_Dictionary*)p;
+  if (CPDF_Dictionary* pDict = p->AsDictionary()) {
+    return pDict;
   }
   if (p->GetType() == PDFOBJ_STREAM) {
     return ((CPDF_Stream*)p)->GetDict();
@@ -663,8 +673,8 @@ CPDF_Dictionary* CPDF_Dictionary::GetDict(const CFX_ByteStringC& key) const {
   if (!p) {
     return nullptr;
   }
-  if (p->GetType() == PDFOBJ_DICTIONARY) {
-    return (CPDF_Dictionary*)p;
+  if (CPDF_Dictionary* pDict = p->AsDictionary()) {
+    return pDict;
   }
   if (p->GetType() == PDFOBJ_STREAM) {
     return ((CPDF_Stream*)p)->GetDict();
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
index 35c1a5892b..6839c07c07 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
@@ -277,8 +277,8 @@ FX_DWORD CPDF_Parser::SetEncryptHandler() {
   }
   CPDF_Object* pEncryptObj = m_pTrailer->GetElement(FX_BSTRC("Encrypt"));
   if (pEncryptObj) {
-    if (pEncryptObj->GetType() == PDFOBJ_DICTIONARY) {
-      SetEncryptDictionary((CPDF_Dictionary*)pEncryptObj);
+    if (CPDF_Dictionary* pEncryptDict = pEncryptObj->AsDictionary()) {
+      SetEncryptDictionary(pEncryptDict);
     } else if (pEncryptObj->GetType() == PDFOBJ_REFERENCE) {
       pEncryptObj = m_pDocument->GetIndirectObject(
           ((CPDF_Reference*)pEncryptObj)->GetRefObjNum());
@@ -804,7 +804,7 @@ FX_BOOL CPDF_Parser::RebuildCrossRef() {
                             if (m_pTrailer) {
                               m_pTrailer->Release();
                             }
-                            m_pTrailer = (CPDF_Dictionary*)pDict->Clone();
+                            m_pTrailer = ToDictionary(pDict->Clone());
                           }
                         }
                       }
@@ -857,15 +857,14 @@ FX_BOOL CPDF_Parser::RebuildCrossRef() {
               m_Syntax.RestorePos(pos + i - m_Syntax.m_HeaderOffset);
               CPDF_Object* pObj = m_Syntax.GetObject(m_pDocument, 0, 0, 0);
               if (pObj) {
-                if (pObj->GetType() != PDFOBJ_DICTIONARY &&
-                    pObj->GetType() != PDFOBJ_STREAM) {
+                if (!pObj->IsDictionary() && pObj->GetType() != PDFOBJ_STREAM) {
                   pObj->Release();
                 } else {
                   CPDF_Dictionary* pTrailer = NULL;
                   if (pObj->GetType() == PDFOBJ_STREAM) {
                     pTrailer = ((CPDF_Stream*)pObj)->GetDict();
                   } else {
-                    pTrailer = (CPDF_Dictionary*)pObj;
+                    pTrailer = pObj->AsDictionary();
                   }
                   if (pTrailer) {
                     if (m_pTrailer) {
@@ -890,7 +889,7 @@ FX_BOOL CPDF_Parser::RebuildCrossRef() {
                       }
                     } else {
                       if (pObj->GetType() == PDFOBJ_STREAM) {
-                        m_pTrailer = (CPDF_Dictionary*)pTrailer->Clone();
+                        m_pTrailer = ToDictionary(pTrailer->Clone());
                         pObj->Release();
                       } else {
                         m_pTrailer = pTrailer;
@@ -1034,13 +1033,13 @@ FX_BOOL CPDF_Parser::LoadCrossRefV5(FX_FILESIZE pos,
     return FALSE;
   }
   if (bMainXRef) {
-    m_pTrailer = (CPDF_Dictionary*)pStream->GetDict()->Clone();
+    m_pTrailer = ToDictionary(pStream->GetDict()->Clone());
     m_CrossRef.SetSize(size);
     if (m_V5Type.SetSize(size)) {
       FXSYS_memset(m_V5Type.GetData(), 0, size);
     }
   } else {
-    m_Trailers.Add((CPDF_Dictionary*)pStream->GetDict()->Clone());
+    m_Trailers.Add(ToDictionary(pStream->GetDict()->Clone()));
   }
   std::vector<std::pair<int32_t, int32_t> > arrIndex;
   CPDF_Array* pArray = pStream->GetDict()->GetArray(FX_BSTRC("Index"));
@@ -1490,9 +1489,9 @@ CPDF_Dictionary* CPDF_Parser::LoadTrailerV4() {
 
   nonstd::unique_ptr<CPDF_Object, ReleaseDeleter<CPDF_Object>> pObj(
       m_Syntax.GetObject(m_pDocument, 0, 0, 0));
-  if (!pObj || pObj->GetType() != PDFOBJ_DICTIONARY)
+  if (!ToDictionary(pObj.get()))
     return nullptr;
-  return static_cast<CPDF_Dictionary*>(pObj.release());
+  return pObj.release()->AsDictionary();
 }
 
 FX_DWORD CPDF_Parser::GetPermissions(FX_BOOL bCheckRevision) {
@@ -3496,7 +3495,7 @@ FX_BOOL CPDF_DataAvail::CheckPage(IFX_DownloadHints* pHints) {
         }
       }
     }
-    if (pObj->GetType() != PDFOBJ_DICTIONARY) {
+    if (!pObj->IsDictionary()) {
       pObj->Release();
       continue;
     }
@@ -4049,7 +4048,7 @@ FX_BOOL CPDF_DataAvail::CheckTrailer(IFX_DownloadHints* pHints) {
       pHints->AddSegment(m_Pos, iTrailerSize);
       return FALSE;
     }
-    if (pTrailer->GetType() != PDFOBJ_DICTIONARY)
+    if (!pTrailer->IsDictionary())
       return FALSE;
 
     CPDF_Dictionary* pTrailerDict = pTrailer->GetDict();
@@ -4164,7 +4163,7 @@ FX_BOOL CPDF_DataAvail::CheckUnkownPageNode(FX_DWORD dwPageNo,
     pPage->Release();
     return TRUE;
   }
-  if (pPage->GetType() != PDFOBJ_DICTIONARY) {
+  if (!pPage->IsDictionary()) {
     pPage->Release();
     m_docStatus = PDF_DATAAVAIL_ERROR;
     return FALSE;
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp
index 63454d2cb5..c34d8122f8 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp
@@ -403,7 +403,7 @@ CFX_ByteTextBuf& operator<<(CFX_ByteTextBuf& buf, const CPDF_Object* pObj) {
       break;
     }
     case PDFOBJ_DICTIONARY: {
-      CPDF_Dictionary* p = (CPDF_Dictionary*)pObj;
+      const CPDF_Dictionary* p = pObj->AsDictionary();
       buf << FX_BSTRC("<<");
       FX_POSITION pos = p->GetStartPos();
       while (pos) {