Rename fpdf_edit_create.cpp to cpdf_creator.cpp

This Cl renames the fpdf_edit_create file to better match the
cpdf_creator content. The CPDF_ObjectStream and CPDF_XRefStream code is
moved out to their own .cpp files. Needed anonymous classes are split
out as well.

Change-Id: Ic83fb319ce28c816db82a4286e22032dc68811bc
Reviewed-on: https://pdfium-review.googlesource.com/5171
Commit-Queue: dsinclair <dsinclair@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Nicolás Peña <npm@chromium.org>

10 files changed, 765 insertions, 646 deletions

diff --git a/BUILD.gn b/BUILD.gn
index adf318e234..a1e487f501 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -435,12 +435,18 @@ static_library("fpdfapi") {
     "core/fpdfapi/cpdf_modulemgr.h",
     "core/fpdfapi/cpdf_pagerendercontext.cpp",
     "core/fpdfapi/cpdf_pagerendercontext.h",
+    "core/fpdfapi/edit/cpdf_creator.cpp",
     "core/fpdfapi/edit/cpdf_creator.h",
+    "core/fpdfapi/edit/cpdf_encryptor.cpp",
+    "core/fpdfapi/edit/cpdf_encryptor.h",
+    "core/fpdfapi/edit/cpdf_flateencoder.cpp",
+    "core/fpdfapi/edit/cpdf_flateencoder.h",
+    "core/fpdfapi/edit/cpdf_objectstream.cpp",
     "core/fpdfapi/edit/cpdf_objectstream.h",
     "core/fpdfapi/edit/cpdf_pagecontentgenerator.cpp",
     "core/fpdfapi/edit/cpdf_pagecontentgenerator.h",
+    "core/fpdfapi/edit/cpdf_xrefstream.cpp",
     "core/fpdfapi/edit/cpdf_xrefstream.h",
-    "core/fpdfapi/edit/fpdf_edit_create.cpp",
     "core/fpdfapi/font/cpdf_cidfont.cpp",
     "core/fpdfapi/font/cpdf_cidfont.h",
     "core/fpdfapi/font/cpdf_font.cpp",
diff --git a/core/fpdfapi/edit/fpdf_edit_create.cpp b/core/fpdfapi/edit/cpdf_creator.cpp
index 42fe13d4e9..32dd28456e 100644
--- a/core/fpdfapi/edit/fpdf_edit_create.cpp
+++ b/core/fpdfapi/edit/cpdf_creator.cpp
@@ -4,134 +4,25 @@
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
-#include <memory>
-#include <vector>
-
 #include "core/fpdfapi/edit/cpdf_creator.h"
+
+#include "core/fpdfapi/edit/cpdf_encryptor.h"
+#include "core/fpdfapi/edit/cpdf_flateencoder.h"
 #include "core/fpdfapi/edit/cpdf_objectstream.h"
 #include "core/fpdfapi/edit/cpdf_xrefstream.h"
 #include "core/fpdfapi/parser/cpdf_array.h"
 #include "core/fpdfapi/parser/cpdf_crypto_handler.h"
-#include "core/fpdfapi/parser/cpdf_dictionary.h"
 #include "core/fpdfapi/parser/cpdf_document.h"
-#include "core/fpdfapi/parser/cpdf_name.h"
 #include "core/fpdfapi/parser/cpdf_number.h"
 #include "core/fpdfapi/parser/cpdf_parser.h"
-#include "core/fpdfapi/parser/cpdf_reference.h"
 #include "core/fpdfapi/parser/cpdf_security_handler.h"
-#include "core/fpdfapi/parser/cpdf_stream.h"
-#include "core/fpdfapi/parser/cpdf_stream_acc.h"
 #include "core/fpdfapi/parser/cpdf_string.h"
 #include "core/fpdfapi/parser/fpdf_parser_decode.h"
-#include "core/fpdfapi/parser/fpdf_parser_utility.h"
-#include "core/fxcrt/cfx_maybe_owned.h"
 #include "core/fxcrt/fx_extension.h"
-#include "third_party/base/numerics/safe_math.h"
-#include "third_party/base/ptr_util.h"
-#include "third_party/base/stl_util.h"
 
 namespace {
 
 const uint32_t kXRefStreamMaxSize = 10000;
-const int kObjectStreamMaxLength = 256 * 1024;
-
-int32_t WriteTrailer(CPDF_Document* pDocument,
-                     CFX_FileBufferArchive* pFile,
-                     CPDF_Array* pIDArray) {
-  FX_FILESIZE offset = 0;
-  int32_t len = 0;
-  CPDF_Parser* pParser = pDocument->GetParser();
-  if (pParser) {
-    CPDF_Dictionary* p = pParser->GetTrailer();
-    for (const auto& it : *p) {
-      const CFX_ByteString& key = it.first;
-      CPDF_Object* pValue = it.second.get();
-      if (key == "Encrypt" || key == "Size" || key == "Filter" ||
-          key == "Index" || key == "Length" || key == "Prev" || key == "W" ||
-          key == "XRefStm" || key == "Type" || key == "ID") {
-        continue;
-      }
-      if (key == "DecodeParms")
-        continue;
-      if (pFile->AppendString(("/")) < 0)
-        return -1;
-      if ((len = pFile->AppendString(PDF_NameEncode(key).AsStringC())) < 0)
-        return -1;
-
-      offset += len + 1;
-      if (!pValue->IsInline()) {
-        if (pFile->AppendString(" ") < 0)
-          return -1;
-        if ((len = pFile->AppendDWord(pValue->GetObjNum())) < 0)
-          return -1;
-        if (pFile->AppendString(" 0 R ") < 0)
-          return -1;
-
-        offset += len + 6;
-      } else {
-        if (!pValue->WriteTo(pFile, &offset))
-          return -1;
-      }
-    }
-    if (pIDArray) {
-      if (pFile->AppendString(("/ID")) < 0)
-        return -1;
-
-      offset += 3;
-      if (!pIDArray->WriteTo(pFile, &offset))
-        return -1;
-    }
-    return offset;
-  }
-  if (pFile->AppendString("\r\n/Root ") < 0)
-    return -1;
-  if ((len = pFile->AppendDWord(pDocument->GetRoot()->GetObjNum())) < 0)
-    return -1;
-  if (pFile->AppendString(" 0 R\r\n") < 0)
-    return -1;
-
-  offset += len + 14;
-  if (pDocument->GetInfo()) {
-    if (pFile->AppendString("/Info ") < 0)
-      return -1;
-    if ((len = pFile->AppendDWord(pDocument->GetInfo()->GetObjNum())) < 0)
-      return -1;
-    if (pFile->AppendString(" 0 R\r\n") < 0)
-      return -1;
-
-    offset += len + 12;
-  }
-  if (pIDArray) {
-    if (pFile->AppendString(("/ID")) < 0)
-      return -1;
-
-    offset += 3;
-    if (!pIDArray->WriteTo(pFile, &offset))
-      return -1;
-  }
-  return offset;
-}
-
-int32_t WriteEncryptDictObjectReference(uint32_t dwObjNum,
-                                        CFX_FileBufferArchive* pFile) {
-  ASSERT(pFile);
-
-  FX_FILESIZE offset = 0;
-  int32_t len = 0;
-  if (pFile->AppendString("/Encrypt") < 0)
-    return -1;
-
-  offset += 8;
-  if (pFile->AppendString(" ") < 0)
-    return -1;
-  if ((len = pFile->AppendDWord(dwObjNum)) < 0)
-    return -1;
-  if (pFile->AppendString(" 0 R ") < 0)
-    return -1;
-
-  offset += len + 6;
-  return offset;
-}
 
 std::vector<uint8_t> GenerateFileID(uint32_t dwSeed1, uint32_t dwSeed2) {
   std::vector<uint8_t> buffer(sizeof(uint32_t) * 4);
@@ -149,38 +40,6 @@ std::vector<uint8_t> GenerateFileID(uint32_t dwSeed1, uint32_t dwSeed2) {
   return buffer;
 }
 
-void AppendIndex0(CFX_ByteTextBuf& buffer, bool bFirstObject) {
-  buffer.AppendByte(0);
-  buffer.AppendByte(0);
-  buffer.AppendByte(0);
-  buffer.AppendByte(0);
-  buffer.AppendByte(0);
-
-  const uint8_t byte = bFirstObject ? 0xFF : 0;
-  buffer.AppendByte(byte);
-  buffer.AppendByte(byte);
-}
-
-void AppendIndex1(CFX_ByteTextBuf& buffer, FX_FILESIZE offset) {
-  buffer.AppendByte(1);
-  buffer.AppendByte(static_cast<uint8_t>(offset >> 24));
-  buffer.AppendByte(static_cast<uint8_t>(offset >> 16));
-  buffer.AppendByte(static_cast<uint8_t>(offset >> 8));
-  buffer.AppendByte(static_cast<uint8_t>(offset));
-  buffer.AppendByte(0);
-  buffer.AppendByte(0);
-}
-
-void AppendIndex2(CFX_ByteTextBuf& buffer, uint32_t objnum, int32_t index) {
-  buffer.AppendByte(2);
-  buffer.AppendByte(static_cast<uint8_t>(objnum >> 24));
-  buffer.AppendByte(static_cast<uint8_t>(objnum >> 16));
-  buffer.AppendByte(static_cast<uint8_t>(objnum >> 8));
-  buffer.AppendByte(static_cast<uint8_t>(objnum));
-  buffer.AppendByte(static_cast<uint8_t>(index >> 8));
-  buffer.AppendByte(static_cast<uint8_t>(index));
-}
-
 int32_t OutputIndex(CFX_FileBufferArchive* pFile, FX_FILESIZE offset) {
   if (pFile->AppendByte(static_cast<uint8_t>(offset >> 24)) < 0)
     return -1;
@@ -195,474 +54,8 @@ int32_t OutputIndex(CFX_FileBufferArchive* pFile, FX_FILESIZE offset) {
   return 0;
 }
 
-class CPDF_FlateEncoder {
- public:
-  CPDF_FlateEncoder(CPDF_Stream* pStream, bool bFlateEncode);
-  CPDF_FlateEncoder(const uint8_t* pBuffer,
-                    uint32_t size,
-                    bool bFlateEncode,
-                    bool bXRefStream);
-  ~CPDF_FlateEncoder();
-
-  void CloneDict();
-
-  uint32_t m_dwSize;
-  CFX_MaybeOwned<uint8_t, FxFreeDeleter> m_pData;
-  CFX_MaybeOwned<CPDF_Dictionary> m_pDict;
-  CFX_RetainPtr<CPDF_StreamAcc> m_pAcc;
-};
-
-CPDF_FlateEncoder::CPDF_FlateEncoder(CPDF_Stream* pStream, bool bFlateEncode)
-    : m_dwSize(0), m_pAcc(pdfium::MakeRetain<CPDF_StreamAcc>(pStream)) {
-  m_pAcc->LoadAllData(true);
-  bool bHasFilter = pStream && pStream->HasFilter();
-  if (bHasFilter && !bFlateEncode) {
-    auto pDestAcc = pdfium::MakeRetain<CPDF_StreamAcc>(pStream);
-    pDestAcc->LoadAllData();
-    m_dwSize = pDestAcc->GetSize();
-    m_pData = pDestAcc->DetachData();
-    m_pDict = ToDictionary(pStream->GetDict()->Clone());
-    m_pDict->RemoveFor("Filter");
-    return;
-  }
-  if (bHasFilter || !bFlateEncode) {
-    m_pData = const_cast<uint8_t*>(m_pAcc->GetData());
-    m_dwSize = m_pAcc->GetSize();
-    m_pDict = pStream->GetDict();
-    return;
-  }
-  // TODO(thestig): Move to Init() and check return value.
-  uint8_t* buffer = nullptr;
-  ::FlateEncode(m_pAcc->GetData(), m_pAcc->GetSize(), &buffer, &m_dwSize);
-  m_pData = std::unique_ptr<uint8_t, FxFreeDeleter>(buffer);
-  m_pDict = ToDictionary(pStream->GetDict()->Clone());
-  m_pDict->SetNewFor<CPDF_Number>("Length", static_cast<int>(m_dwSize));
-  m_pDict->SetNewFor<CPDF_Name>("Filter", "FlateDecode");
-  m_pDict->RemoveFor("DecodeParms");
-}
-
-CPDF_FlateEncoder::CPDF_FlateEncoder(const uint8_t* pBuffer,
-                                     uint32_t size,
-                                     bool bFlateEncode,
-                                     bool bXRefStream)
-    : m_dwSize(0) {
-  if (!bFlateEncode) {
-    m_pData = const_cast<uint8_t*>(pBuffer);
-    m_dwSize = size;
-    return;
-  }
-  uint8_t* buffer = nullptr;
-  // TODO(thestig): Move to Init() and check return value.
-  if (bXRefStream)
-    ::PngEncode(pBuffer, size, &buffer, &m_dwSize);
-  else
-    ::FlateEncode(pBuffer, size, &buffer, &m_dwSize);
-  m_pData = std::unique_ptr<uint8_t, FxFreeDeleter>(buffer);
-}
-
-CPDF_FlateEncoder::~CPDF_FlateEncoder() {}
-
-void CPDF_FlateEncoder::CloneDict() {
-  if (m_pDict.IsOwned())
-    return;
-
-  m_pDict = ToDictionary(m_pDict->Clone());
-  ASSERT(m_pDict.IsOwned());
-}
-
-class CPDF_Encryptor {
- public:
-  CPDF_Encryptor(CPDF_CryptoHandler* pHandler,
-                 int objnum,
-                 uint8_t* src_data,
-                 uint32_t src_size);
-  ~CPDF_Encryptor();
-
-  uint8_t* m_pData;
-  uint32_t m_dwSize;
-  bool m_bNewBuf;
-};
-
-CPDF_Encryptor::CPDF_Encryptor(CPDF_CryptoHandler* pHandler,
-                               int objnum,
-                               uint8_t* src_data,
-                               uint32_t src_size)
-    : m_pData(nullptr), m_dwSize(0), m_bNewBuf(false) {
-  if (src_size == 0)
-    return;
-
-  if (!pHandler) {
-    m_pData = (uint8_t*)src_data;
-    m_dwSize = src_size;
-    return;
-  }
-  m_dwSize = pHandler->EncryptGetSize(objnum, 0, src_data, src_size);
-  m_pData = FX_Alloc(uint8_t, m_dwSize);
-  pHandler->EncryptContent(objnum, 0, src_data, src_size, m_pData, m_dwSize);
-  m_bNewBuf = true;
-}
-
-CPDF_Encryptor::~CPDF_Encryptor() {
-  if (m_bNewBuf)
-    FX_Free(m_pData);
-}
-
 }  // namespace
 
-CPDF_ObjectStream::CPDF_ObjectStream() : m_dwObjNum(0), m_index(0) {}
-
-CPDF_ObjectStream::~CPDF_ObjectStream() {}
-
-void CPDF_ObjectStream::Start() {
-  m_Items.clear();
-  m_Buffer.Clear();
-  m_dwObjNum = 0;
-  m_index = 0;
-}
-
-void CPDF_ObjectStream::CompressIndirectObject(uint32_t dwObjNum,
-                                               const CPDF_Object* pObj) {
-  m_Items.push_back({dwObjNum, m_Buffer.GetLength()});
-  m_Buffer << pObj;
-}
-
-void CPDF_ObjectStream::CompressIndirectObject(uint32_t dwObjNum,
-                                               const uint8_t* pBuffer,
-                                               uint32_t dwSize) {
-  m_Items.push_back({dwObjNum, m_Buffer.GetLength()});
-  m_Buffer.AppendBlock(pBuffer, dwSize);
-}
-
-FX_FILESIZE CPDF_ObjectStream::End(CPDF_Creator* pCreator) {
-  ASSERT(pCreator);
-  if (m_Items.empty())
-    return 0;
-
-  CFX_FileBufferArchive* pFile = pCreator->GetFile();
-  FX_FILESIZE ObjOffset = pCreator->GetOffset();
-  if (!m_dwObjNum)
-    m_dwObjNum = pCreator->GetNextObjectNumber();
-
-  CFX_ByteTextBuf tempBuffer;
-  for (const auto& pair : m_Items)
-    tempBuffer << pair.objnum << " " << pair.offset << " ";
-
-  int32_t len = pFile->AppendDWord(m_dwObjNum);
-  if (len < 0)
-    return -1;
-
-  pCreator->IncrementOffset(len);
-  if ((len = pFile->AppendString(" 0 obj\r\n<</Type /ObjStm /N ")) < 0)
-    return -1;
-
-  pCreator->IncrementOffset(len);
-  uint32_t iCount = pdfium::CollectionSize<uint32_t>(m_Items);
-  if ((len = pFile->AppendDWord(iCount)) < 0)
-    return -1;
-
-  pCreator->IncrementOffset(len);
-  if (pFile->AppendString("/First ") < 0)
-    return -1;
-  if ((len = pFile->AppendDWord((uint32_t)tempBuffer.GetLength())) < 0)
-    return -1;
-  if (pFile->AppendString("/Length ") < 0)
-    return -1;
-
-  pCreator->IncrementOffset(len + 15);
-
-  tempBuffer << m_Buffer;
-  CPDF_FlateEncoder encoder(tempBuffer.GetBuffer(), tempBuffer.GetLength(),
-                            true, false);
-  CPDF_Encryptor encryptor(pCreator->GetCryptoHandler(), m_dwObjNum,
-                           encoder.m_pData.Get(), encoder.m_dwSize);
-  if ((len = pFile->AppendDWord(encryptor.m_dwSize)) < 0)
-    return -1;
-
-  pCreator->IncrementOffset(len);
-  if (pFile->AppendString("/Filter /FlateDecode") < 0)
-    return -1;
-
-  pCreator->IncrementOffset(20);
-  if ((len = pFile->AppendString(">>stream\r\n")) < 0)
-    return -1;
-  if (pFile->AppendBlock(encryptor.m_pData, encryptor.m_dwSize) < 0)
-    return -1;
-
-  pCreator->IncrementOffset(len + encryptor.m_dwSize);
-  if ((len = pFile->AppendString("\r\nendstream\r\nendobj\r\n")) < 0)
-    return -1;
-
-  pCreator->IncrementOffset(len);
-  return ObjOffset;
-}
-
-CPDF_XRefStream::CPDF_XRefStream()
-    : m_PrevOffset(0), m_dwTempObjNum(0), m_iSeg(0) {}
-
-CPDF_XRefStream::~CPDF_XRefStream() {}
-
-bool CPDF_XRefStream::Start() {
-  m_IndexArray.clear();
-  m_Buffer.Clear();
-  m_iSeg = 0;
-  return true;
-}
-
-int32_t CPDF_XRefStream::CompressIndirectObject(uint32_t dwObjNum,
-                                                const CPDF_Object* pObj,
-                                                CPDF_Creator* pCreator) {
-  if (!pCreator)
-    return 0;
-
-  m_ObjStream.CompressIndirectObject(dwObjNum, pObj);
-  if (pdfium::CollectionSize<int32_t>(m_ObjStream.m_Items) <
-          pCreator->GetObjectStreamSize() &&
-      m_ObjStream.m_Buffer.GetLength() < kObjectStreamMaxLength) {
-    return 1;
-  }
-  return EndObjectStream(pCreator, true);
-}
-
-int32_t CPDF_XRefStream::CompressIndirectObject(uint32_t dwObjNum,
-                                                const uint8_t* pBuffer,
-                                                uint32_t dwSize,
-                                                CPDF_Creator* pCreator) {
-  if (!pCreator)
-    return 0;
-
-  m_ObjStream.CompressIndirectObject(dwObjNum, pBuffer, dwSize);
-  if (pdfium::CollectionSize<int32_t>(m_ObjStream.m_Items) <
-          pCreator->GetObjectStreamSize() &&
-      m_ObjStream.m_Buffer.GetLength() < kObjectStreamMaxLength) {
-    return 1;
-  }
-  return EndObjectStream(pCreator, true);
-}
-
-int32_t CPDF_XRefStream::EndObjectStream(CPDF_Creator* pCreator, bool bEOF) {
-  FX_FILESIZE objOffset = 0;
-  if (bEOF) {
-    objOffset = m_ObjStream.End(pCreator);
-    if (objOffset < 0)
-      return -1;
-  }
-
-  uint32_t& dwObjStmNum = m_ObjStream.m_dwObjNum;
-  if (!dwObjStmNum)
-    dwObjStmNum = pCreator->GetNextObjectNumber();
-
-  int32_t iSize = pdfium::CollectionSize<int32_t>(m_ObjStream.m_Items);
-  size_t iSeg = m_IndexArray.size();
-  if (!pCreator->IsIncremental()) {
-    if (m_dwTempObjNum == 0) {
-      AppendIndex0(m_Buffer, true);
-      m_dwTempObjNum++;
-    }
-    uint32_t end_num = m_IndexArray.back().objnum + m_IndexArray.back().count;
-    int index = 0;
-    for (; m_dwTempObjNum < end_num; m_dwTempObjNum++) {
-      if (pCreator->HasObjectNumber(m_dwTempObjNum)) {
-        if (index >= iSize ||
-            m_dwTempObjNum != m_ObjStream.m_Items[index].objnum) {
-          AppendIndex1(m_Buffer, pCreator->GetObjectOffset(m_dwTempObjNum));
-        } else {
-          AppendIndex2(m_Buffer, dwObjStmNum, index++);
-        }
-      } else {
-        AppendIndex0(m_Buffer, false);
-      }
-    }
-    if (iSize > 0 && bEOF)
-      pCreator->SetObjectOffset(dwObjStmNum, objOffset);
-
-    m_iSeg = iSeg;
-    if (bEOF)
-      m_ObjStream.Start();
-
-    return 1;
-  }
-  for (auto it = m_IndexArray.begin() + m_iSeg; it != m_IndexArray.end();
-       ++it) {
-    for (uint32_t m = it->objnum; m < it->objnum + it->count; ++m) {
-      if (m_ObjStream.m_index >= iSize ||
-          m != m_ObjStream.m_Items[it - m_IndexArray.begin()].objnum) {
-        AppendIndex1(m_Buffer, pCreator->GetObjectOffset(m));
-      } else {
-        AppendIndex2(m_Buffer, dwObjStmNum, m_ObjStream.m_index++);
-      }
-    }
-  }
-  if (iSize > 0 && bEOF) {
-    AppendIndex1(m_Buffer, objOffset);
-    m_IndexArray.push_back({dwObjStmNum, 1});
-    iSeg += 1;
-  }
-  m_iSeg = iSeg;
-  if (bEOF)
-    m_ObjStream.Start();
-
-  return 1;
-}
-
-bool CPDF_XRefStream::GenerateXRefStream(CPDF_Creator* pCreator, bool bEOF) {
-  FX_FILESIZE offset_tmp = pCreator->GetOffset();
-  uint32_t objnum = pCreator->GetNextObjectNumber();
-  CFX_FileBufferArchive* pFile = pCreator->GetFile();
-  if (pCreator->IsIncremental()) {
-    AddObjectNumberToIndexArray(objnum);
-  } else {
-    for (; m_dwTempObjNum < pCreator->GetLastObjectNumber(); m_dwTempObjNum++) {
-      if (pCreator->HasObjectNumber(m_dwTempObjNum))
-        AppendIndex1(m_Buffer, pCreator->GetObjectOffset(m_dwTempObjNum));
-      else
-        AppendIndex0(m_Buffer, false);
-    }
-  }
-
-  AppendIndex1(m_Buffer, offset_tmp);
-
-  int32_t len = pFile->AppendDWord(objnum);
-  if (len < 0)
-    return false;
-
-  pCreator->IncrementOffset(len);
-  if ((len = pFile->AppendString(" 0 obj\r\n<</Type /XRef/W[1 4 2]/Index[")) <
-      0) {
-    return false;
-  }
-  pCreator->IncrementOffset(len);
-  if (!pCreator->IsIncremental()) {
-    if ((len = pFile->AppendDWord(0)) < 0)
-      return false;
-    if ((len = pFile->AppendString(" ")) < 0)
-      return false;
-
-    pCreator->IncrementOffset(len + 1);
-    if ((len = pFile->AppendDWord(objnum + 1)) < 0)
-      return false;
-
-    pCreator->IncrementOffset(len);
-  } else {
-    for (const auto& pair : m_IndexArray) {
-      if ((len = pFile->AppendDWord(pair.objnum)) < 0)
-        return false;
-      if (pFile->AppendString(" ") < 0)
-        return false;
-
-      pCreator->IncrementOffset(len + 1);
-      if ((len = pFile->AppendDWord(pair.count)) < 0)
-        return false;
-      if (pFile->AppendString(" ") < 0)
-        return false;
-
-      pCreator->IncrementOffset(len + 1);
-    }
-  }
-  if (pFile->AppendString("]/Size ") < 0)
-    return false;
-  if ((len = pFile->AppendDWord(objnum + 1)) < 0)
-    return false;
-
-  pCreator->IncrementOffset(len + 7);
-  if (m_PrevOffset > 0) {
-    if (pFile->AppendString("/Prev ") < 0)
-      return false;
-
-    char offset_buf[20];
-    memset(offset_buf, 0, sizeof(offset_buf));
-    FXSYS_i64toa(m_PrevOffset, offset_buf, 10);
-    int32_t offset_len = (int32_t)FXSYS_strlen(offset_buf);
-    if (pFile->AppendBlock(offset_buf, offset_len) < 0)
-      return false;
-
-    pCreator->IncrementOffset(offset_len + 6);
-  }
-
-  CPDF_FlateEncoder encoder(m_Buffer.GetBuffer(), m_Buffer.GetLength(), true,
-                            true);
-  if (pFile->AppendString("/Filter /FlateDecode") < 0)
-    return false;
-
-  pCreator->IncrementOffset(20);
-  if ((len = pFile->AppendString("/DecodeParms<</Columns 7/Predictor 12>>")) <
-      0) {
-    return false;
-  }
-
-  pCreator->IncrementOffset(len);
-  if (pFile->AppendString("/Length ") < 0)
-    return false;
-  if ((len = pFile->AppendDWord(encoder.m_dwSize)) < 0)
-    return false;
-
-  pCreator->IncrementOffset(len + 8);
-  if (bEOF) {
-    if ((len = WriteTrailer(pCreator->GetDocument(), pFile,
-                            pCreator->GetIDArray())) < 0) {
-      return false;
-    }
-    pCreator->IncrementOffset(len);
-
-    if (CPDF_Dictionary* encryptDict = pCreator->GetEncryptDict()) {
-      uint32_t dwEncryptObjNum = encryptDict->GetObjNum();
-      if (dwEncryptObjNum == 0)
-        dwEncryptObjNum = pCreator->GetEncryptObjectNumber();
-      if ((len = WriteEncryptDictObjectReference(dwEncryptObjNum, pFile)) < 0)
-        return false;
-      pCreator->IncrementOffset(len);
-    }
-  }
-  if ((len = pFile->AppendString(">>stream\r\n")) < 0)
-    return false;
-
-  pCreator->IncrementOffset(len);
-  if (pFile->AppendBlock(encoder.m_pData.Get(), encoder.m_dwSize) < 0)
-    return false;
-  if ((len = pFile->AppendString("\r\nendstream\r\nendobj\r\n")) < 0)
-    return false;
-
-  pCreator->IncrementOffset(encoder.m_dwSize + len);
-  m_PrevOffset = offset_tmp;
-  return true;
-}
-
-bool CPDF_XRefStream::End(CPDF_Creator* pCreator, bool bEOF) {
-  if (EndObjectStream(pCreator, bEOF) < 0)
-    return false;
-  return GenerateXRefStream(pCreator, bEOF);
-}
-
-bool CPDF_XRefStream::EndXRefStream(CPDF_Creator* pCreator) {
-  if (!pCreator->IsIncremental()) {
-    AppendIndex0(m_Buffer, true);
-    for (uint32_t i = 1; i < pCreator->GetLastObjectNumber() + 1; i++) {
-      if (pCreator->HasObjectNumber(i))
-        AppendIndex1(m_Buffer, pCreator->GetObjectOffset(i));
-      else
-        AppendIndex0(m_Buffer, false);
-    }
-  } else {
-    for (const auto& pair : m_IndexArray) {
-      for (uint32_t j = pair.objnum; j < pair.objnum + pair.count; ++j)
-        AppendIndex1(m_Buffer, pCreator->GetObjectOffset(j));
-    }
-  }
-  return GenerateXRefStream(pCreator, false);
-}
-
-void CPDF_XRefStream::AddObjectNumberToIndexArray(uint32_t objnum) {
-  if (m_IndexArray.empty()) {
-    m_IndexArray.push_back({objnum, 1});
-    return;
-  }
-
-  uint32_t next_objnum = m_IndexArray.back().objnum + m_IndexArray.back().count;
-  if (objnum == next_objnum)
-    m_IndexArray.back().count += 1;
-  else
-    m_IndexArray.push_back({objnum, 1});
-}
-
 CPDF_Creator::CPDF_Creator(CPDF_Document* pDoc)
     : m_pDocument(pDoc),
       m_pParser(pDoc->GetParser()),
@@ -689,12 +82,7 @@ CPDF_Creator::~CPDF_Creator() {
 bool CPDF_Creator::IsXRefNeedEnd() {
   if (!IsIncremental())
     return false;
-
-  uint32_t iCount = 0;
-  for (const auto& pair : m_pXRefStream->m_IndexArray)
-    iCount += pair.count;
-
-  return iCount >= kXRefStreamMaxSize;
+  return m_pXRefStream->CountIndexArrayItems() >= kXRefStreamMaxSize;
 }
 
 int32_t CPDF_Creator::WriteIndirectObjectToStream(const CPDF_Object* pObj) {
@@ -773,15 +161,15 @@ int32_t CPDF_Creator::WriteStream(const CPDF_Object* pStream,
                                   CPDF_CryptoHandler* pCrypto) {
   CPDF_FlateEncoder encoder(const_cast<CPDF_Stream*>(pStream->AsStream()),
                             pStream != m_pMetadata);
-  CPDF_Encryptor encryptor(pCrypto, objnum, encoder.m_pData.Get(),
-                           encoder.m_dwSize);
-  if (static_cast<uint32_t>(encoder.m_pDict->GetIntegerFor("Length")) !=
-      encryptor.m_dwSize) {
+  CPDF_Encryptor encryptor(pCrypto, objnum, encoder.GetData(),
+                           encoder.GetSize());
+  if (static_cast<uint32_t>(encoder.GetDict()->GetIntegerFor("Length")) !=
+      encryptor.GetSize()) {
     encoder.CloneDict();
-    encoder.m_pDict->SetNewFor<CPDF_Number>(
-        "Length", static_cast<int>(encryptor.m_dwSize));
+    encoder.GetDict()->SetNewFor<CPDF_Number>(
+        "Length", static_cast<int>(encryptor.GetSize()));
   }
-  if (WriteDirectObj(objnum, encoder.m_pDict.Get()) < 0)
+  if (WriteDirectObj(objnum, encoder.GetDict()) < 0)
     return -1;
 
   int len = m_File.AppendString("stream\r\n");
@@ -789,10 +177,10 @@ int32_t CPDF_Creator::WriteStream(const CPDF_Object* pStream,
     return -1;
 
   m_Offset += len;
-  if (m_File.AppendBlock(encryptor.m_pData, encryptor.m_dwSize) < 0)
+  if (m_File.AppendBlock(encryptor.GetData(), encryptor.GetSize()) < 0)
     return -1;
 
-  m_Offset += encryptor.m_dwSize;
+  m_Offset += encryptor.GetSize();
   if ((len = m_File.AppendString("\r\nendstream")) < 0)
     return -1;
 
@@ -860,8 +248,7 @@ int32_t CPDF_Creator::WriteDirectObj(uint32_t objnum,
       CPDF_Encryptor encryptor(m_pCryptoHandler.Get(), objnum,
                                (uint8_t*)str.c_str(), str.GetLength());
       CFX_ByteString content = PDF_EncodeString(
-          CFX_ByteString((const char*)encryptor.m_pData, encryptor.m_dwSize),
-          bHex);
+          CFX_ByteString(encryptor.GetData(), encryptor.GetSize()), bHex);
       int32_t len = m_File.AppendString(content.AsStringC());
       if (len < 0)
         return -1;
@@ -873,14 +260,14 @@ int32_t CPDF_Creator::WriteDirectObj(uint32_t objnum,
       CPDF_FlateEncoder encoder(const_cast<CPDF_Stream*>(pObj->AsStream()),
                                 true);
       CPDF_Encryptor encryptor(m_pCryptoHandler.Get(), objnum,
-                               encoder.m_pData.Get(), encoder.m_dwSize);
-      if (static_cast<uint32_t>(encoder.m_pDict->GetIntegerFor("Length")) !=
-          encryptor.m_dwSize) {
+                               encoder.GetData(), encoder.GetSize());
+      if (static_cast<uint32_t>(encoder.GetDict()->GetIntegerFor("Length")) !=
+          encryptor.GetSize()) {
         encoder.CloneDict();
-        encoder.m_pDict->SetNewFor<CPDF_Number>(
-            "Length", static_cast<int>(encryptor.m_dwSize));
+        encoder.GetDict()->SetNewFor<CPDF_Number>(
+            "Length", static_cast<int>(encryptor.GetSize()));
       }
-      if (WriteDirectObj(objnum, encoder.m_pDict.Get()) < 0)
+      if (WriteDirectObj(objnum, encoder.GetDict()) < 0)
         return -1;
 
       int32_t len = m_File.AppendString("stream\r\n");
@@ -888,10 +275,10 @@ int32_t CPDF_Creator::WriteDirectObj(uint32_t objnum,
         return -1;
 
       m_Offset += len;
-      if (m_File.AppendBlock(encryptor.m_pData, encryptor.m_dwSize) < 0)
+      if (m_File.AppendBlock(encryptor.GetData(), encryptor.GetSize()) < 0)
         return -1;
 
-      m_Offset += encryptor.m_dwSize;
+      m_Offset += encryptor.GetSize();
       len = m_File.AppendString("\r\nendstream");
       if (len < 0)
         return -1;
@@ -1129,10 +516,8 @@ int32_t CPDF_Creator::WriteDoc_Stage1() {
     if (m_dwFlags & FPDFCREATE_OBJECTSTREAM) {
       m_pXRefStream = pdfium::MakeUnique<CPDF_XRefStream>();
       m_pXRefStream->Start();
-      if (IsIncremental() && m_pParser) {
-        FX_FILESIZE prev = m_pParser->GetLastXRefOffset();
-        m_pXRefStream->m_PrevOffset = prev;
-      }
+      if (IsIncremental() && m_pParser)
+        m_pXRefStream->SetPreviousOffset(m_pParser->GetLastXRefOffset());
     }
     m_iStage = 10;
   }
@@ -1261,7 +646,7 @@ int32_t CPDF_Creator::WriteDoc_Stage3() {
     m_XrefStart = m_Offset;
     if (m_dwFlags & FPDFCREATE_OBJECTSTREAM) {
       m_pXRefStream->End(this, true);
-      m_XrefStart = m_pXRefStream->m_PrevOffset;
+      m_XrefStart = m_pXRefStream->GetPreviousOffset();
       m_iStage = 90;
     } else if (!IsIncremental() || !m_pParser->IsXRefStream()) {
       if (!IsIncremental() || m_pParser->GetLastXRefOffset() == 0) {
@@ -1373,7 +758,8 @@ int32_t CPDF_Creator::WriteDoc_Stage4() {
       for (const auto& it : *p) {
         const CFX_ByteString& key = it.first;
         CPDF_Object* pValue = it.second.get();
-        // TODO(ochang): Consolidate with similar check in WriteTrailer.
+        // TODO(ochang): Consolidate with similar check in
+        // CPDF_XRefStream::WriteTrailer.
         if (key == "Encrypt" || key == "Size" || key == "Filter" ||
             key == "Index" || key == "Length" || key == "Prev" || key == "W" ||
             key == "XRefStm" || key == "ID") {
diff --git a/core/fpdfapi/edit/cpdf_encryptor.cpp b/core/fpdfapi/edit/cpdf_encryptor.cpp
new file mode 100644
index 0000000000..858b5b6369
--- /dev/null
+++ b/core/fpdfapi/edit/cpdf_encryptor.cpp
@@ -0,0 +1,32 @@
+// Copyright 2017 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 "core/fpdfapi/edit/cpdf_encryptor.h"
+#include "core/fpdfapi/parser/cpdf_crypto_handler.h"
+
+CPDF_Encryptor::CPDF_Encryptor(CPDF_CryptoHandler* pHandler,
+                               int objnum,
+                               uint8_t* src_data,
+                               uint32_t src_size)
+    : m_pData(nullptr), m_dwSize(0), m_bNewBuf(false) {
+  if (src_size == 0)
+    return;
+
+  if (!pHandler) {
+    m_pData = (uint8_t*)src_data;
+    m_dwSize = src_size;
+    return;
+  }
+  m_dwSize = pHandler->EncryptGetSize(objnum, 0, src_data, src_size);
+  m_pData = FX_Alloc(uint8_t, m_dwSize);
+  pHandler->EncryptContent(objnum, 0, src_data, src_size, m_pData, m_dwSize);
+  m_bNewBuf = true;
+}
+
+CPDF_Encryptor::~CPDF_Encryptor() {
+  if (m_bNewBuf)
+    FX_Free(m_pData);
+}
diff --git a/core/fpdfapi/edit/cpdf_encryptor.h b/core/fpdfapi/edit/cpdf_encryptor.h
new file mode 100644
index 0000000000..00c9337eb3
--- /dev/null
+++ b/core/fpdfapi/edit/cpdf_encryptor.h
@@ -0,0 +1,31 @@
+// Copyright 2017 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
+
+#ifndef CORE_FPDFAPI_EDIT_CPDF_ENCRYPTOR_H_
+#define CORE_FPDFAPI_EDIT_CPDF_ENCRYPTOR_H_
+
+#include <stdint.h>
+
+class CPDF_CryptoHandler;
+
+class CPDF_Encryptor {
+ public:
+  CPDF_Encryptor(CPDF_CryptoHandler* pHandler,
+                 int objnum,
+                 uint8_t* src_data,
+                 uint32_t src_size);
+  ~CPDF_Encryptor();
+
+  uint32_t GetSize() const { return m_dwSize; }
+  uint8_t* GetData() const { return m_pData; }
+
+ private:
+  uint8_t* m_pData;
+  uint32_t m_dwSize;
+  bool m_bNewBuf;
+};
+
+#endif  // CORE_FPDFAPI_EDIT_CPDF_ENCRYPTOR_H_
diff --git a/core/fpdfapi/edit/cpdf_flateencoder.cpp b/core/fpdfapi/edit/cpdf_flateencoder.cpp
new file mode 100644
index 0000000000..55d436f573
--- /dev/null
+++ b/core/fpdfapi/edit/cpdf_flateencoder.cpp
@@ -0,0 +1,77 @@
+// Copyright 2017 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 "core/fpdfapi/edit/cpdf_flateencoder.h"
+
+#include <memory>
+
+#include "core/fpdfapi/parser/cpdf_name.h"
+#include "core/fpdfapi/parser/cpdf_number.h"
+#include "core/fpdfapi/parser/fpdf_parser_decode.h"
+
+CPDF_FlateEncoder::CPDF_FlateEncoder(CPDF_Stream* pStream, bool bFlateEncode)
+    : m_dwSize(0), m_pAcc(pdfium::MakeRetain<CPDF_StreamAcc>(pStream)) {
+  m_pAcc->LoadAllData(true);
+
+  bool bHasFilter = pStream && pStream->HasFilter();
+  if (bHasFilter && !bFlateEncode) {
+    auto pDestAcc = pdfium::MakeRetain<CPDF_StreamAcc>(pStream);
+    pDestAcc->LoadAllData();
+
+    m_dwSize = pDestAcc->GetSize();
+    m_pData = pDestAcc->DetachData();
+    m_pDict = ToDictionary(pStream->GetDict()->Clone());
+    m_pDict->RemoveFor("Filter");
+    return;
+  }
+  if (bHasFilter || !bFlateEncode) {
+    m_pData = const_cast<uint8_t*>(m_pAcc->GetData());
+    m_dwSize = m_pAcc->GetSize();
+    m_pDict = pStream->GetDict();
+    return;
+  }
+
+  // TODO(thestig): Move to Init() and check return value.
+  uint8_t* buffer = nullptr;
+  ::FlateEncode(m_pAcc->GetData(), m_pAcc->GetSize(), &buffer, &m_dwSize);
+
+  m_pData = std::unique_ptr<uint8_t, FxFreeDeleter>(buffer);
+  m_pDict = ToDictionary(pStream->GetDict()->Clone());
+  m_pDict->SetNewFor<CPDF_Number>("Length", static_cast<int>(m_dwSize));
+  m_pDict->SetNewFor<CPDF_Name>("Filter", "FlateDecode");
+  m_pDict->RemoveFor("DecodeParms");
+}
+
+CPDF_FlateEncoder::CPDF_FlateEncoder(const uint8_t* pBuffer,
+                                     uint32_t size,
+                                     bool bFlateEncode,
+                                     bool bXRefStream)
+    : m_dwSize(0) {
+  if (!bFlateEncode) {
+    m_pData = const_cast<uint8_t*>(pBuffer);
+    m_dwSize = size;
+    return;
+  }
+
+  uint8_t* buffer = nullptr;
+  // TODO(thestig): Move to Init() and check return value.
+  if (bXRefStream)
+    ::PngEncode(pBuffer, size, &buffer, &m_dwSize);
+  else
+    ::FlateEncode(pBuffer, size, &buffer, &m_dwSize);
+
+  m_pData = std::unique_ptr<uint8_t, FxFreeDeleter>(buffer);
+}
+
+CPDF_FlateEncoder::~CPDF_FlateEncoder() {}
+
+void CPDF_FlateEncoder::CloneDict() {
+  if (m_pDict.IsOwned())
+    return;
+
+  m_pDict = ToDictionary(m_pDict->Clone());
+  ASSERT(m_pDict.IsOwned());
+}
diff --git a/core/fpdfapi/edit/cpdf_flateencoder.h b/core/fpdfapi/edit/cpdf_flateencoder.h
new file mode 100644
index 0000000000..ac850e2802
--- /dev/null
+++ b/core/fpdfapi/edit/cpdf_flateencoder.h
@@ -0,0 +1,41 @@
+// Copyright 2017 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
+
+#ifndef CORE_FPDFAPI_EDIT_CPDF_FLATEENCODER_H_
+#define CORE_FPDFAPI_EDIT_CPDF_FLATEENCODER_H_
+
+#include "core/fpdfapi/parser/cpdf_dictionary.h"
+#include "core/fpdfapi/parser/cpdf_stream_acc.h"
+#include "core/fxcrt/cfx_maybe_owned.h"
+#include "core/fxcrt/cfx_retain_ptr.h"
+#include "core/fxcrt/fx_memory.h"
+
+class CPDF_Stream;
+
+class CPDF_FlateEncoder {
+ public:
+  CPDF_FlateEncoder(CPDF_Stream* pStream, bool bFlateEncode);
+  CPDF_FlateEncoder(const uint8_t* pBuffer,
+                    uint32_t size,
+                    bool bFlateEncode,
+                    bool bXRefStream);
+  ~CPDF_FlateEncoder();
+
+  void CloneDict();
+
+  uint32_t GetSize() const { return m_dwSize; }
+  uint8_t* GetData() const { return m_pData.Get(); }
+
+  CPDF_Dictionary* GetDict() { return m_pDict.Get(); }
+
+ private:
+  uint32_t m_dwSize;
+  CFX_MaybeOwned<uint8_t, FxFreeDeleter> m_pData;
+  CFX_MaybeOwned<CPDF_Dictionary> m_pDict;
+  CFX_RetainPtr<CPDF_StreamAcc> m_pAcc;
+};
+
+#endif  // CORE_FPDFAPI_EDIT_CPDF_FLATEENCODER_H_
diff --git a/core/fpdfapi/edit/cpdf_objectstream.cpp b/core/fpdfapi/edit/cpdf_objectstream.cpp
new file mode 100644
index 0000000000..e3f6e4c8e9
--- /dev/null
+++ b/core/fpdfapi/edit/cpdf_objectstream.cpp
@@ -0,0 +1,109 @@
+// Copyright 2017 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 "core/fpdfapi/edit/cpdf_objectstream.h"
+
+#include "core/fpdfapi/edit/cpdf_creator.h"
+#include "core/fpdfapi/edit/cpdf_encryptor.h"
+#include "core/fpdfapi/edit/cpdf_flateencoder.h"
+#include "core/fpdfapi/parser/fpdf_parser_utility.h"
+
+namespace {
+
+const int kObjectStreamMaxLength = 256 * 1024;
+
+}  // namespace
+
+CPDF_ObjectStream::CPDF_ObjectStream() : m_dwObjNum(0), m_index(0) {}
+
+CPDF_ObjectStream::~CPDF_ObjectStream() {}
+
+bool CPDF_ObjectStream::IsNotFull() const {
+  return m_Buffer.GetLength() < kObjectStreamMaxLength;
+}
+
+void CPDF_ObjectStream::Start() {
+  m_Items.clear();
+  m_Buffer.Clear();
+  m_dwObjNum = 0;
+  m_index = 0;
+}
+
+void CPDF_ObjectStream::CompressIndirectObject(uint32_t dwObjNum,
+                                               const CPDF_Object* pObj) {
+  m_Items.push_back({dwObjNum, m_Buffer.GetLength()});
+  m_Buffer << pObj;
+}
+
+void CPDF_ObjectStream::CompressIndirectObject(uint32_t dwObjNum,
+                                               const uint8_t* pBuffer,
+                                               uint32_t dwSize) {
+  m_Items.push_back({dwObjNum, m_Buffer.GetLength()});
+  m_Buffer.AppendBlock(pBuffer, dwSize);
+}
+
+FX_FILESIZE CPDF_ObjectStream::End(CPDF_Creator* pCreator) {
+  ASSERT(pCreator);
+  if (m_Items.empty())
+    return 0;
+
+  CFX_FileBufferArchive* pFile = pCreator->GetFile();
+  FX_FILESIZE ObjOffset = pCreator->GetOffset();
+  if (!m_dwObjNum)
+    m_dwObjNum = pCreator->GetNextObjectNumber();
+
+  CFX_ByteTextBuf tempBuffer;
+  for (const auto& pair : m_Items)
+    tempBuffer << pair.objnum << " " << pair.offset << " ";
+
+  int32_t len = pFile->AppendDWord(m_dwObjNum);
+  if (len < 0)
+    return -1;
+
+  pCreator->IncrementOffset(len);
+  if ((len = pFile->AppendString(" 0 obj\r\n<</Type /ObjStm /N ")) < 0)
+    return -1;
+
+  pCreator->IncrementOffset(len);
+  uint32_t iCount = pdfium::CollectionSize<uint32_t>(m_Items);
+  if ((len = pFile->AppendDWord(iCount)) < 0)
+    return -1;
+
+  pCreator->IncrementOffset(len);
+  if (pFile->AppendString("/First ") < 0)
+    return -1;
+  if ((len = pFile->AppendDWord((uint32_t)tempBuffer.GetLength())) < 0)
+    return -1;
+  if (pFile->AppendString("/Length ") < 0)
+    return -1;
+
+  pCreator->IncrementOffset(len + 15);
+
+  tempBuffer << m_Buffer;
+  CPDF_FlateEncoder encoder(tempBuffer.GetBuffer(), tempBuffer.GetLength(),
+                            true, false);
+  CPDF_Encryptor encryptor(pCreator->GetCryptoHandler(), m_dwObjNum,
+                           encoder.GetData(), encoder.GetSize());
+  if ((len = pFile->AppendDWord(encryptor.GetSize())) < 0)
+    return -1;
+
+  pCreator->IncrementOffset(len);
+  if (pFile->AppendString("/Filter /FlateDecode") < 0)
+    return -1;
+
+  pCreator->IncrementOffset(20);
+  if ((len = pFile->AppendString(">>stream\r\n")) < 0)
+    return -1;
+  if (pFile->AppendBlock(encryptor.GetData(), encryptor.GetSize()) < 0)
+    return -1;
+
+  pCreator->IncrementOffset(len + encryptor.GetSize());
+  if ((len = pFile->AppendString("\r\nendstream\r\nendobj\r\n")) < 0)
+    return -1;
+
+  pCreator->IncrementOffset(len);
+  return ObjOffset;
+}
diff --git a/core/fpdfapi/edit/cpdf_objectstream.h b/core/fpdfapi/edit/cpdf_objectstream.h
index 3e5c5a72a9..5ad6ec8085 100644
--- a/core/fpdfapi/edit/cpdf_objectstream.h
+++ b/core/fpdfapi/edit/cpdf_objectstream.h
@@ -10,6 +10,7 @@
 #include <vector>
 
 #include "core/fxcrt/fx_basic.h"
+#include "third_party/base/stl_util.h"
 
 class CPDF_Creator;
 class CPDF_Object;
@@ -31,6 +32,18 @@ class CPDF_ObjectStream {
                               const uint8_t* pBuffer,
                               uint32_t dwSize);
 
+  bool IsNotFull() const;
+  int32_t ItemCount() const { return pdfium::CollectionSize<int32_t>(m_Items); }
+  void SetObjectNumber(uint32_t num) { m_dwObjNum = num; }
+  uint32_t GetObjectNumber() const { return m_dwObjNum; }
+  int32_t GetIndex() const { return m_index; }
+  void IncrementIndex() { m_index++; }
+
+  uint32_t GetObjectNumberForItem(int index) const {
+    return m_Items[index].objnum;
+  }
+
+ private:
   std::vector<Item> m_Items;
   CFX_ByteTextBuf m_Buffer;
   uint32_t m_dwObjNum;
diff --git a/core/fpdfapi/edit/cpdf_xrefstream.cpp b/core/fpdfapi/edit/cpdf_xrefstream.cpp
new file mode 100644
index 0000000000..9ec27f291c
--- /dev/null
+++ b/core/fpdfapi/edit/cpdf_xrefstream.cpp
@@ -0,0 +1,412 @@
+// Copyright 2017 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 "core/fpdfapi/edit/cpdf_xrefstream.h"
+
+#include "core/fpdfapi/edit/cpdf_creator.h"
+#include "core/fpdfapi/edit/cpdf_flateencoder.h"
+#include "core/fpdfapi/parser/cpdf_array.h"
+#include "core/fpdfapi/parser/cpdf_document.h"
+#include "core/fpdfapi/parser/cpdf_parser.h"
+#include "core/fpdfapi/parser/fpdf_parser_decode.h"
+
+namespace {
+
+int32_t WriteTrailer(CPDF_Document* pDocument,
+                     CFX_FileBufferArchive* pFile,
+                     CPDF_Array* pIDArray) {
+  FX_FILESIZE offset = 0;
+  int32_t len = 0;
+  CPDF_Parser* pParser = pDocument->GetParser();
+  if (pParser) {
+    CPDF_Dictionary* p = pParser->GetTrailer();
+    for (const auto& it : *p) {
+      const CFX_ByteString& key = it.first;
+      CPDF_Object* pValue = it.second.get();
+      if (key == "Encrypt" || key == "Size" || key == "Filter" ||
+          key == "Index" || key == "Length" || key == "Prev" || key == "W" ||
+          key == "XRefStm" || key == "Type" || key == "ID") {
+        continue;
+      }
+      if (key == "DecodeParms")
+        continue;
+      if (pFile->AppendString(("/")) < 0)
+        return -1;
+      if ((len = pFile->AppendString(PDF_NameEncode(key).AsStringC())) < 0)
+        return -1;
+
+      offset += len + 1;
+      if (!pValue->IsInline()) {
+        if (pFile->AppendString(" ") < 0)
+          return -1;
+        if ((len = pFile->AppendDWord(pValue->GetObjNum())) < 0)
+          return -1;
+        if (pFile->AppendString(" 0 R ") < 0)
+          return -1;
+
+        offset += len + 6;
+      } else {
+        if (!pValue->WriteTo(pFile, &offset))
+          return -1;
+      }
+    }
+    if (pIDArray) {
+      if (pFile->AppendString(("/ID")) < 0)
+        return -1;
+
+      offset += 3;
+      if (!pIDArray->WriteTo(pFile, &offset))
+        return -1;
+    }
+    return offset;
+  }
+  if (pFile->AppendString("\r\n/Root ") < 0)
+    return -1;
+  if ((len = pFile->AppendDWord(pDocument->GetRoot()->GetObjNum())) < 0)
+    return -1;
+  if (pFile->AppendString(" 0 R\r\n") < 0)
+    return -1;
+
+  offset += len + 14;
+  if (pDocument->GetInfo()) {
+    if (pFile->AppendString("/Info ") < 0)
+      return -1;
+    if ((len = pFile->AppendDWord(pDocument->GetInfo()->GetObjNum())) < 0)
+      return -1;
+    if (pFile->AppendString(" 0 R\r\n") < 0)
+      return -1;
+
+    offset += len + 12;
+  }
+  if (pIDArray) {
+    if (pFile->AppendString(("/ID")) < 0)
+      return -1;
+
+    offset += 3;
+    if (!pIDArray->WriteTo(pFile, &offset))
+      return -1;
+  }
+  return offset;
+}
+
+int32_t WriteEncryptDictObjectReference(uint32_t dwObjNum,
+                                        CFX_FileBufferArchive* pFile) {
+  ASSERT(pFile);
+
+  FX_FILESIZE offset = 0;
+  int32_t len = 0;
+  if (pFile->AppendString("/Encrypt") < 0)
+    return -1;
+
+  offset += 8;
+  if (pFile->AppendString(" ") < 0)
+    return -1;
+  if ((len = pFile->AppendDWord(dwObjNum)) < 0)
+    return -1;
+  if (pFile->AppendString(" 0 R ") < 0)
+    return -1;
+
+  offset += len + 6;
+  return offset;
+}
+
+void AppendIndex0(CFX_ByteTextBuf& buffer, bool bFirstObject) {
+  buffer.AppendByte(0);
+  buffer.AppendByte(0);
+  buffer.AppendByte(0);
+  buffer.AppendByte(0);
+  buffer.AppendByte(0);
+
+  const uint8_t byte = bFirstObject ? 0xFF : 0;
+  buffer.AppendByte(byte);
+  buffer.AppendByte(byte);
+}
+
+void AppendIndex1(CFX_ByteTextBuf& buffer, FX_FILESIZE offset) {
+  buffer.AppendByte(1);
+  buffer.AppendByte(static_cast<uint8_t>(offset >> 24));
+  buffer.AppendByte(static_cast<uint8_t>(offset >> 16));
+  buffer.AppendByte(static_cast<uint8_t>(offset >> 8));
+  buffer.AppendByte(static_cast<uint8_t>(offset));
+  buffer.AppendByte(0);
+  buffer.AppendByte(0);
+}
+
+void AppendIndex2(CFX_ByteTextBuf& buffer, uint32_t objnum, int32_t index) {
+  buffer.AppendByte(2);
+  buffer.AppendByte(static_cast<uint8_t>(objnum >> 24));
+  buffer.AppendByte(static_cast<uint8_t>(objnum >> 16));
+  buffer.AppendByte(static_cast<uint8_t>(objnum >> 8));
+  buffer.AppendByte(static_cast<uint8_t>(objnum));
+  buffer.AppendByte(static_cast<uint8_t>(index >> 8));
+  buffer.AppendByte(static_cast<uint8_t>(index));
+}
+
+}  // namespace
+
+CPDF_XRefStream::CPDF_XRefStream()
+    : m_PrevOffset(0), m_dwTempObjNum(0), m_iSeg(0) {}
+
+CPDF_XRefStream::~CPDF_XRefStream() {}
+
+bool CPDF_XRefStream::Start() {
+  m_IndexArray.clear();
+  m_Buffer.Clear();
+  m_iSeg = 0;
+  return true;
+}
+
+int32_t CPDF_XRefStream::CompressIndirectObject(uint32_t dwObjNum,
+                                                const CPDF_Object* pObj,
+                                                CPDF_Creator* pCreator) {
+  ASSERT(pCreator);
+
+  m_ObjStream.CompressIndirectObject(dwObjNum, pObj);
+  if (m_ObjStream.ItemCount() < pCreator->GetObjectStreamSize() &&
+      m_ObjStream.IsNotFull()) {
+    return 1;
+  }
+  return EndObjectStream(pCreator, true);
+}
+
+int32_t CPDF_XRefStream::CompressIndirectObject(uint32_t dwObjNum,
+                                                const uint8_t* pBuffer,
+                                                uint32_t dwSize,
+                                                CPDF_Creator* pCreator) {
+  ASSERT(pCreator);
+
+  m_ObjStream.CompressIndirectObject(dwObjNum, pBuffer, dwSize);
+  if (m_ObjStream.ItemCount() < pCreator->GetObjectStreamSize() &&
+      m_ObjStream.IsNotFull()) {
+    return 1;
+  }
+  return EndObjectStream(pCreator, true);
+}
+
+int32_t CPDF_XRefStream::EndObjectStream(CPDF_Creator* pCreator, bool bEOF) {
+  FX_FILESIZE objOffset = 0;
+  if (bEOF) {
+    objOffset = m_ObjStream.End(pCreator);
+    if (objOffset < 0)
+      return -1;
+  }
+
+  if (!m_ObjStream.GetObjectNumber())
+    m_ObjStream.SetObjectNumber(pCreator->GetNextObjectNumber());
+
+  int32_t iSize = m_ObjStream.ItemCount();
+  size_t iSeg = m_IndexArray.size();
+  if (!pCreator->IsIncremental()) {
+    if (m_dwTempObjNum == 0) {
+      AppendIndex0(m_Buffer, true);
+      m_dwTempObjNum++;
+    }
+    uint32_t end_num = m_IndexArray.back().objnum + m_IndexArray.back().count;
+    int index = 0;
+    for (; m_dwTempObjNum < end_num; m_dwTempObjNum++) {
+      if (pCreator->HasObjectNumber(m_dwTempObjNum)) {
+        if (index >= iSize ||
+            m_dwTempObjNum != m_ObjStream.GetObjectNumberForItem(index)) {
+          AppendIndex1(m_Buffer, pCreator->GetObjectOffset(m_dwTempObjNum));
+        } else {
+          AppendIndex2(m_Buffer, m_ObjStream.GetObjectNumber(), index++);
+        }
+      } else {
+        AppendIndex0(m_Buffer, false);
+      }
+    }
+    if (iSize > 0 && bEOF)
+      pCreator->SetObjectOffset(m_ObjStream.GetObjectNumber(), objOffset);
+
+    m_iSeg = iSeg;
+    if (bEOF)
+      m_ObjStream.Start();
+
+    return 1;
+  }
+  for (auto it = m_IndexArray.begin() + m_iSeg; it != m_IndexArray.end();
+       ++it) {
+    for (uint32_t m = it->objnum; m < it->objnum + it->count; ++m) {
+      if (m_ObjStream.GetIndex() >= iSize ||
+          m != m_ObjStream.GetObjectNumberForItem(it - m_IndexArray.begin())) {
+        AppendIndex1(m_Buffer, pCreator->GetObjectOffset(m));
+      } else {
+        AppendIndex2(m_Buffer, m_ObjStream.GetObjectNumber(),
+                     m_ObjStream.GetIndex());
+        m_ObjStream.IncrementIndex();
+      }
+    }
+  }
+  if (iSize > 0 && bEOF) {
+    AppendIndex1(m_Buffer, objOffset);
+    m_IndexArray.push_back({m_ObjStream.GetObjectNumber(), 1});
+    iSeg += 1;
+  }
+  m_iSeg = iSeg;
+  if (bEOF)
+    m_ObjStream.Start();
+
+  return 1;
+}
+
+bool CPDF_XRefStream::GenerateXRefStream(CPDF_Creator* pCreator, bool bEOF) {
+  FX_FILESIZE offset_tmp = pCreator->GetOffset();
+  uint32_t objnum = pCreator->GetNextObjectNumber();
+  CFX_FileBufferArchive* pFile = pCreator->GetFile();
+  if (pCreator->IsIncremental()) {
+    AddObjectNumberToIndexArray(objnum);
+  } else {
+    for (; m_dwTempObjNum < pCreator->GetLastObjectNumber(); m_dwTempObjNum++) {
+      if (pCreator->HasObjectNumber(m_dwTempObjNum))
+        AppendIndex1(m_Buffer, pCreator->GetObjectOffset(m_dwTempObjNum));
+      else
+        AppendIndex0(m_Buffer, false);
+    }
+  }
+
+  AppendIndex1(m_Buffer, offset_tmp);
+
+  int32_t len = pFile->AppendDWord(objnum);
+  if (len < 0)
+    return false;
+
+  pCreator->IncrementOffset(len);
+  if ((len = pFile->AppendString(" 0 obj\r\n<</Type /XRef/W[1 4 2]/Index[")) <
+      0) {
+    return false;
+  }
+  pCreator->IncrementOffset(len);
+  if (!pCreator->IsIncremental()) {
+    if ((len = pFile->AppendDWord(0)) < 0)
+      return false;
+    if ((len = pFile->AppendString(" ")) < 0)
+      return false;
+
+    pCreator->IncrementOffset(len + 1);
+    if ((len = pFile->AppendDWord(objnum + 1)) < 0)
+      return false;
+
+    pCreator->IncrementOffset(len);
+  } else {
+    for (const auto& pair : m_IndexArray) {
+      if ((len = pFile->AppendDWord(pair.objnum)) < 0)
+        return false;
+      if (pFile->AppendString(" ") < 0)
+        return false;
+
+      pCreator->IncrementOffset(len + 1);
+      if ((len = pFile->AppendDWord(pair.count)) < 0)
+        return false;
+      if (pFile->AppendString(" ") < 0)
+        return false;
+
+      pCreator->IncrementOffset(len + 1);
+    }
+  }
+  if (pFile->AppendString("]/Size ") < 0)
+    return false;
+  if ((len = pFile->AppendDWord(objnum + 1)) < 0)
+    return false;
+
+  pCreator->IncrementOffset(len + 7);
+  if (m_PrevOffset > 0) {
+    if (pFile->AppendString("/Prev ") < 0)
+      return false;
+
+    char offset_buf[20];
+    memset(offset_buf, 0, sizeof(offset_buf));
+    FXSYS_i64toa(m_PrevOffset, offset_buf, 10);
+    int32_t offset_len = (int32_t)FXSYS_strlen(offset_buf);
+    if (pFile->AppendBlock(offset_buf, offset_len) < 0)
+      return false;
+
+    pCreator->IncrementOffset(offset_len + 6);
+  }
+
+  CPDF_FlateEncoder encoder(m_Buffer.GetBuffer(), m_Buffer.GetLength(), true,
+                            true);
+  if (pFile->AppendString("/Filter /FlateDecode") < 0)
+    return false;
+
+  pCreator->IncrementOffset(20);
+  if ((len = pFile->AppendString("/DecodeParms<</Columns 7/Predictor 12>>")) <
+      0) {
+    return false;
+  }
+
+  pCreator->IncrementOffset(len);
+  if (pFile->AppendString("/Length ") < 0)
+    return false;
+  if ((len = pFile->AppendDWord(encoder.GetSize())) < 0)
+    return false;
+
+  pCreator->IncrementOffset(len + 8);
+  if (bEOF) {
+    if ((len = WriteTrailer(pCreator->GetDocument(), pFile,
+                            pCreator->GetIDArray())) < 0) {
+      return false;
+    }
+    pCreator->IncrementOffset(len);
+
+    if (CPDF_Dictionary* encryptDict = pCreator->GetEncryptDict()) {
+      uint32_t dwEncryptObjNum = encryptDict->GetObjNum();
+      if (dwEncryptObjNum == 0)
+        dwEncryptObjNum = pCreator->GetEncryptObjectNumber();
+      if ((len = WriteEncryptDictObjectReference(dwEncryptObjNum, pFile)) < 0)
+        return false;
+      pCreator->IncrementOffset(len);
+    }
+  }
+  if ((len = pFile->AppendString(">>stream\r\n")) < 0)
+    return false;
+
+  pCreator->IncrementOffset(len);
+  if (pFile->AppendBlock(encoder.GetData(), encoder.GetSize()) < 0)
+    return false;
+  if ((len = pFile->AppendString("\r\nendstream\r\nendobj\r\n")) < 0)
+    return false;
+
+  pCreator->IncrementOffset(encoder.GetSize() + len);
+  m_PrevOffset = offset_tmp;
+  return true;
+}
+
+bool CPDF_XRefStream::End(CPDF_Creator* pCreator, bool bEOF) {
+  if (EndObjectStream(pCreator, bEOF) < 0)
+    return false;
+  return GenerateXRefStream(pCreator, bEOF);
+}
+
+bool CPDF_XRefStream::EndXRefStream(CPDF_Creator* pCreator) {
+  if (!pCreator->IsIncremental()) {
+    AppendIndex0(m_Buffer, true);
+    for (uint32_t i = 1; i < pCreator->GetLastObjectNumber() + 1; i++) {
+      if (pCreator->HasObjectNumber(i))
+        AppendIndex1(m_Buffer, pCreator->GetObjectOffset(i));
+      else
+        AppendIndex0(m_Buffer, false);
+    }
+  } else {
+    for (const auto& pair : m_IndexArray) {
+      for (uint32_t j = pair.objnum; j < pair.objnum + pair.count; ++j)
+        AppendIndex1(m_Buffer, pCreator->GetObjectOffset(j));
+    }
+  }
+  return GenerateXRefStream(pCreator, false);
+}
+
+void CPDF_XRefStream::AddObjectNumberToIndexArray(uint32_t objnum) {
+  if (m_IndexArray.empty()) {
+    m_IndexArray.push_back({objnum, 1});
+    return;
+  }
+
+  uint32_t next_objnum = m_IndexArray.back().objnum + m_IndexArray.back().count;
+  if (objnum == next_objnum)
+    m_IndexArray.back().count += 1;
+  else
+    m_IndexArray.push_back({objnum, 1});
+}
diff --git a/core/fpdfapi/edit/cpdf_xrefstream.h b/core/fpdfapi/edit/cpdf_xrefstream.h
index cb11261f9f..2ca990732b 100644
--- a/core/fpdfapi/edit/cpdf_xrefstream.h
+++ b/core/fpdfapi/edit/cpdf_xrefstream.h
@@ -9,6 +9,9 @@
 
 #include <vector>
 
+#include "core/fpdfapi/edit/cpdf_objectstream.h"
+#include "core/fxcrt/fx_basic.h"
+
 class CPDF_Creator;
 class CPDF_Object;
 
@@ -34,14 +37,23 @@ class CPDF_XRefStream {
   void AddObjectNumberToIndexArray(uint32_t objnum);
   bool EndXRefStream(CPDF_Creator* pCreator);
 
-  std::vector<Index> m_IndexArray;
-  FX_FILESIZE m_PrevOffset;
-  uint32_t m_dwTempObjNum;
+  FX_FILESIZE GetPreviousOffset() const { return m_PrevOffset; }
+  void SetPreviousOffset(FX_FILESIZE offset) { m_PrevOffset = offset; }
 
- protected:
+  uint32_t CountIndexArrayItems() const {
+    uint32_t size = 0;
+    for (const auto& pair : m_IndexArray)
+      size += pair.count;
+    return size;
+  }
+
+ private:
   int32_t EndObjectStream(CPDF_Creator* pCreator, bool bEOF);
   bool GenerateXRefStream(CPDF_Creator* pCreator, bool bEOF);
 
+  std::vector<Index> m_IndexArray;
+  FX_FILESIZE m_PrevOffset;
+  uint32_t m_dwTempObjNum;
   size_t m_iSeg;
   CPDF_ObjectStream m_ObjStream;
   CFX_ByteTextBuf m_Buffer;