From a18536af5b32b63f795d8b5812a4303c7ee6ea97 Mon Sep 17 00:00:00 2001
From: Artem Strygin <art-snake@yandex-team.ru>
Date: Wed, 18 Jul 2018 03:42:38 +0000
Subject: Make CPDF_Parser::GetTrailer const method.

Use own copy of encryption dictionary within CPDF_Parser,
to prevent modification of original trailer.

Change-Id: I6246b872d431b94411fcec694c5176f8d85dfe26
Reviewed-on: https://pdfium-review.googlesource.com/35450
Commit-Queue: Art Snake <art-snake@yandex-team.ru>
Reviewed-by: Lei Zhang <thestig@chromium.org>
---
 core/fpdfapi/parser/cpdf_parser.cpp | 14 +++++++-------
 core/fpdfapi/parser/cpdf_parser.h   |  8 ++++----
 2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/core/fpdfapi/parser/cpdf_parser.cpp b/core/fpdfapi/parser/cpdf_parser.cpp
index f7846eff31..8d4d7728ab 100644
--- a/core/fpdfapi/parser/cpdf_parser.cpp
+++ b/core/fpdfapi/parser/cpdf_parser.cpp
@@ -185,8 +185,8 @@ bool CPDF_Parser::IsObjectFree(uint32_t objnum) const {
   return GetObjectType(objnum) == ObjectType::kFree;
 }
 
-void CPDF_Parser::SetEncryptDictionary(CPDF_Dictionary* pDict) {
-  m_pEncryptDict = pDict;
+void CPDF_Parser::SetEncryptDictionary(const CPDF_Dictionary* pDict) {
+  m_pEncryptDict = pDict ? ToDictionary(pDict->Clone()) : nullptr;
 }
 
 RetainPtr<IFX_SeekableReadStream> CPDF_Parser::GetFileAccess() const {
@@ -338,11 +338,11 @@ CPDF_Parser::Error CPDF_Parser::SetEncryptHandler() {
   if (!GetTrailer())
     return FORMAT_ERROR;
 
-  CPDF_Object* pEncryptObj = GetTrailer()->GetObjectFor("Encrypt");
+  const CPDF_Object* pEncryptObj = GetTrailer()->GetObjectFor("Encrypt");
   if (pEncryptObj) {
-    if (CPDF_Dictionary* pEncryptDict = pEncryptObj->AsDictionary()) {
+    if (const CPDF_Dictionary* pEncryptDict = pEncryptObj->AsDictionary()) {
       SetEncryptDictionary(pEncryptDict);
-    } else if (CPDF_Reference* pRef = pEncryptObj->AsReference()) {
+    } else if (const CPDF_Reference* pRef = pEncryptObj->AsReference()) {
       pEncryptObj =
           m_pObjectsHolder->GetOrParseIndirectObject(pRef->GetRefObjNum());
       if (pEncryptObj)
@@ -357,7 +357,7 @@ CPDF_Parser::Error CPDF_Parser::SetEncryptHandler() {
 
     std::unique_ptr<CPDF_SecurityHandler> pSecurityHandler =
         pdfium::MakeUnique<CPDF_SecurityHandler>();
-    if (!pSecurityHandler->OnInit(m_pEncryptDict.Get(), GetIDArray(),
+    if (!pSecurityHandler->OnInit(m_pEncryptDict.get(), GetIDArray(),
                                   m_Password))
       return PASSWORD_ERROR;
 
@@ -1112,7 +1112,7 @@ CPDF_Dictionary* CPDF_Parser::GetRoot() const {
   return obj ? obj->GetDict() : nullptr;
 }
 
-CPDF_Dictionary* CPDF_Parser::GetTrailer() const {
+const CPDF_Dictionary* CPDF_Parser::GetTrailer() const {
   return m_TrailerData->GetMainTrailer();
 }
 
diff --git a/core/fpdfapi/parser/cpdf_parser.h b/core/fpdfapi/parser/cpdf_parser.h
index c998063394..e9b2a760ea 100644
--- a/core/fpdfapi/parser/cpdf_parser.h
+++ b/core/fpdfapi/parser/cpdf_parser.h
@@ -64,7 +64,7 @@ class CPDF_Parser {
   void SetPassword(const char* password) { m_Password = password; }
   ByteString GetPassword() const { return m_Password; }
 
-  CPDF_Dictionary* GetTrailer() const;
+  const CPDF_Dictionary* GetTrailer() const;
 
   // Returns a new trailer which combines the last read trailer with the /Root
   // and /Info from previous ones.
@@ -78,7 +78,7 @@ class CPDF_Parser {
   const CPDF_Array* GetIDArray() const;
   CPDF_Dictionary* GetRoot() const;
 
-  CPDF_Dictionary* GetEncryptDict() const { return m_pEncryptDict.Get(); }
+  CPDF_Dictionary* GetEncryptDict() const { return m_pEncryptDict.get(); }
 
   std::unique_ptr<CPDF_Object> ParseIndirectObject(uint32_t objnum);
 
@@ -159,7 +159,7 @@ class CPDF_Parser {
   Error LoadLinearizedMainXRefTable();
   const CPDF_ObjectStream* GetObjectStream(uint32_t object_number);
   std::unique_ptr<CPDF_LinearizedHeader> ParseLinearizedHeader();
-  void SetEncryptDictionary(CPDF_Dictionary* pDict);
+  void SetEncryptDictionary(const CPDF_Dictionary* pDict);
   void ShrinkObjectMap(uint32_t size);
   // A simple check whether the cross reference table matches with
   // the objects.
@@ -190,7 +190,7 @@ class CPDF_Parser {
   // m_TrailerData must be destroyed after m_pSecurityHandler due to the
   // ownership of the ID array data.
   std::unique_ptr<TrailerData> m_TrailerData;
-  UnownedPtr<CPDF_Dictionary> m_pEncryptDict;
+  std::unique_ptr<CPDF_Dictionary> m_pEncryptDict;
   FX_FILESIZE m_LastXRefOffset;
   std::unique_ptr<CPDF_SecurityHandler> m_pSecurityHandler;
   ByteString m_Password;
-- 
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