Rename fgas_stream to ifgas_stream

This Cl renames the the fgas_stream files to match the internal
ifgas_stream class. The majority of the code in ifgas_stream.cpp is
moved into the anonymouse namespace.

Change-Id: I0518103d61df077782d9ab26d0ac87485417f379
Reviewed-on: https://pdfium-review.googlesource.com/3370
Reviewed-by: Nicolás Peña <npm@chromium.org>
Commit-Queue: dsinclair <dsinclair@chromium.org>

1 files changed, 1481 insertions, 0 deletions

diff --git a/xfa/fgas/crt/ifgas_stream.cpp b/xfa/fgas/crt/ifgas_stream.cpp
new file mode 100644
index 0000000000..eef19a59ff
--- /dev/null
+++ b/xfa/fgas/crt/ifgas_stream.cpp
@@ -0,0 +1,1481 @@
+// Copyright 2014 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 "xfa/fgas/crt/ifgas_stream.h"
+
+#if _FX_OS_ == _FX_WIN32_DESKTOP_ || _FX_OS_ == _FX_WIN32_MOBILE_ || \
+    _FX_OS_ == _FX_WIN64_
+#include <io.h>
+#endif
+
+#include <algorithm>
+#include <memory>
+
+#include "third_party/base/ptr_util.h"
+#include "xfa/fgas/crt/fgas_codepage.h"
+
+namespace {
+
+class IFGAS_StreamImp {
+ public:
+  virtual ~IFGAS_StreamImp() {}
+
+  virtual int32_t GetLength() const = 0;
+  virtual int32_t Seek(FX_STREAMSEEK eSeek, int32_t iOffset) = 0;
+  virtual int32_t GetPosition() = 0;
+  virtual bool IsEOF() const = 0;
+  virtual int32_t ReadData(uint8_t* pBuffer, int32_t iBufferSize) = 0;
+  virtual int32_t ReadString(wchar_t* pStr, int32_t iMaxLength, bool& bEOS) = 0;
+  virtual int32_t WriteData(const uint8_t* pBuffer, int32_t iBufferSize) = 0;
+  virtual int32_t WriteString(const wchar_t* pStr, int32_t iLength) = 0;
+  virtual void Flush() = 0;
+  virtual bool SetLength(int32_t iLength) = 0;
+
+ protected:
+  IFGAS_StreamImp();
+
+  uint32_t GetAccessModes() const { return m_dwAccess; }
+  void SetAccessModes(uint32_t modes) { m_dwAccess = modes; }
+
+ private:
+  uint32_t m_dwAccess;
+};
+
+class CFGAS_FileStreamImp : public IFGAS_StreamImp {
+ public:
+  CFGAS_FileStreamImp();
+  ~CFGAS_FileStreamImp() override;
+
+  bool LoadFile(const wchar_t* pszSrcFileName, uint32_t dwAccess);
+
+  // IFGAS_StreamImp:
+  int32_t GetLength() const override;
+  int32_t Seek(FX_STREAMSEEK eSeek, int32_t iOffset) override;
+  int32_t GetPosition() override;
+  bool IsEOF() const override;
+  int32_t ReadData(uint8_t* pBuffer, int32_t iBufferSize) override;
+  int32_t ReadString(wchar_t* pStr, int32_t iMaxLength, bool& bEOS) override;
+  int32_t WriteData(const uint8_t* pBuffer, int32_t iBufferSize) override;
+  int32_t WriteString(const wchar_t* pStr, int32_t iLength) override;
+  void Flush() override;
+  bool SetLength(int32_t iLength) override;
+
+ protected:
+  FXSYS_FILE* m_hFile;
+  int32_t m_iLength;
+};
+
+class CFGAS_BufferStreamImp : public IFGAS_StreamImp {
+ public:
+  CFGAS_BufferStreamImp();
+  ~CFGAS_BufferStreamImp() override {}
+
+  bool LoadBuffer(uint8_t* pData, int32_t iTotalSize, uint32_t dwAccess);
+
+  // IFGAS_StreamImp:
+  int32_t GetLength() const override;
+  int32_t Seek(FX_STREAMSEEK eSeek, int32_t iOffset) override;
+  int32_t GetPosition() override;
+  bool IsEOF() const override;
+  int32_t ReadData(uint8_t* pBuffer, int32_t iBufferSize) override;
+  int32_t ReadString(wchar_t* pStr, int32_t iMaxLength, bool& bEOS) override;
+  int32_t WriteData(const uint8_t* pBuffer, int32_t iBufferSize) override;
+  int32_t WriteString(const wchar_t* pStr, int32_t iLength) override;
+  void Flush() override {}
+  bool SetLength(int32_t iLength) override { return false; }
+
+ protected:
+  uint8_t* m_pData;
+  int32_t m_iTotalSize;
+  int32_t m_iPosition;
+  int32_t m_iLength;
+};
+
+class CFGAS_FileReadStreamImp : public IFGAS_StreamImp {
+ public:
+  CFGAS_FileReadStreamImp();
+  ~CFGAS_FileReadStreamImp() override {}
+
+  bool LoadFileRead(const CFX_RetainPtr<IFX_SeekableReadStream>& pFileRead,
+                    uint32_t dwAccess);
+
+  // IFGAS_StreamImp:
+  int32_t GetLength() const override;
+  int32_t Seek(FX_STREAMSEEK eSeek, int32_t iOffset) override;
+  int32_t GetPosition() override { return m_iPosition; }
+  bool IsEOF() const override;
+  int32_t ReadData(uint8_t* pBuffer, int32_t iBufferSize) override;
+  int32_t ReadString(wchar_t* pStr, int32_t iMaxLength, bool& bEOS) override;
+  int32_t WriteData(const uint8_t* pBuffer, int32_t iBufferSize) override {
+    return 0;
+  }
+  int32_t WriteString(const wchar_t* pStr, int32_t iLength) override {
+    return 0;
+  }
+  void Flush() override {}
+  bool SetLength(int32_t iLength) override { return false; }
+
+ protected:
+  CFX_RetainPtr<IFX_SeekableReadStream> m_pFileRead;
+  int32_t m_iPosition;
+  int32_t m_iLength;
+};
+
+class CFGAS_BufferReadStreamImp : public IFGAS_StreamImp {
+ public:
+  CFGAS_BufferReadStreamImp();
+  ~CFGAS_BufferReadStreamImp() override;
+
+  bool LoadBufferRead(const CFX_RetainPtr<IFX_BufferedReadStream>& pBufferRead,
+                      int32_t iFileSize,
+                      uint32_t dwAccess);
+
+  // IFGAS_StreamImp:
+  int32_t GetLength() const override;
+  int32_t Seek(FX_STREAMSEEK eSeek, int32_t iOffset) override;
+  int32_t GetPosition() override { return m_iPosition; }
+  bool IsEOF() const override;
+  int32_t ReadData(uint8_t* pBuffer, int32_t iBufferSize) override;
+  int32_t ReadString(wchar_t* pStr, int32_t iMaxLength, bool& bEOS) override;
+  int32_t WriteData(const uint8_t* pBuffer, int32_t iBufferSize) override {
+    return 0;
+  }
+  int32_t WriteString(const wchar_t* pStr, int32_t iLength) override {
+    return 0;
+  }
+  void Flush() override {}
+  bool SetLength(int32_t iLength) override { return false; }
+
+ private:
+  CFX_RetainPtr<IFX_BufferedReadStream> m_pBufferRead;
+  int32_t m_iPosition;
+  int32_t m_iBufferSize;
+};
+
+class CFGAS_FileWriteStreamImp : public IFGAS_StreamImp {
+ public:
+  CFGAS_FileWriteStreamImp();
+  ~CFGAS_FileWriteStreamImp() override {}
+
+  bool LoadFileWrite(const CFX_RetainPtr<IFX_SeekableWriteStream>& pFileWrite,
+                     uint32_t dwAccess);
+
+  // IFGAS_StreamImp:
+  int32_t GetLength() const override;
+  int32_t Seek(FX_STREAMSEEK eSeek, int32_t iOffset) override;
+  int32_t GetPosition() override { return m_iPosition; }
+  bool IsEOF() const override;
+  int32_t ReadData(uint8_t* pBuffer, int32_t iBufferSize) override { return 0; }
+  int32_t ReadString(wchar_t* pStr, int32_t iMaxLength, bool& bEOS) override {
+    return 0;
+  }
+  int32_t WriteData(const uint8_t* pBuffer, int32_t iBufferSize) override;
+  int32_t WriteString(const wchar_t* pStr, int32_t iLength) override;
+  void Flush() override;
+  bool SetLength(int32_t iLength) override { return false; }
+
+ protected:
+  CFX_RetainPtr<IFX_SeekableWriteStream> m_pFileWrite;
+  int32_t m_iPosition;
+};
+
+enum FX_STREAMTYPE {
+  FX_SREAMTYPE_Unknown = 0,
+  FX_STREAMTYPE_File,
+  FX_STREAMTYPE_Buffer,
+  FX_STREAMTYPE_Stream,
+  FX_STREAMTYPE_BufferRead,
+};
+
+class CFGAS_Stream : public IFGAS_Stream {
+ public:
+  template <typename T, typename... Args>
+  friend CFX_RetainPtr<T> pdfium::MakeRetain(Args&&... args);
+
+  bool LoadFile(const wchar_t* pszSrcFileName, uint32_t dwAccess);
+  bool LoadBuffer(uint8_t* pData, int32_t iTotalSize, uint32_t dwAccess);
+  bool LoadFileRead(const CFX_RetainPtr<IFX_SeekableReadStream>& pFileRead,
+                    uint32_t dwAccess);
+  bool LoadFileWrite(const CFX_RetainPtr<IFX_SeekableWriteStream>& pFileWrite,
+                     uint32_t dwAccess);
+  bool LoadBufferRead(const CFX_RetainPtr<IFX_BufferedReadStream>& pBufferRead,
+                      int32_t iFileSize,
+                      uint32_t dwAccess);
+
+  // IFGAS_Stream
+  uint32_t GetAccessModes() const override;
+  int32_t GetLength() const override;
+  int32_t Seek(FX_STREAMSEEK eSeek, int32_t iOffset) override;
+  int32_t GetPosition() override;
+  bool IsEOF() const override;
+  int32_t ReadData(uint8_t* pBuffer, int32_t iBufferSize) override;
+  int32_t ReadString(wchar_t* pStr, int32_t iMaxLength, bool& bEOS) override;
+  int32_t WriteData(const uint8_t* pBuffer, int32_t iBufferSize) override;
+  int32_t WriteString(const wchar_t* pStr, int32_t iLength) override;
+  void Flush() override;
+  bool SetLength(int32_t iLength) override;
+  int32_t GetBOM(uint8_t bom[4]) const override;
+  uint16_t GetCodePage() const override;
+  uint16_t SetCodePage(uint16_t wCodePage) override;
+  CFX_RetainPtr<IFGAS_Stream> CreateSharedStream(uint32_t dwAccess,
+                                                 int32_t iOffset,
+                                                 int32_t iLength) override;
+
+ protected:
+  CFGAS_Stream();
+  ~CFGAS_Stream() override;
+
+  FX_STREAMTYPE m_eStreamType;
+  IFGAS_StreamImp* m_pStreamImp;
+  uint32_t m_dwAccess;
+  int32_t m_iTotalSize;
+  int32_t m_iPosition;
+  int32_t m_iStart;
+  int32_t m_iLength;
+  int32_t m_iRefCount;
+};
+
+class CFGAS_TextStream : public IFGAS_Stream {
+ public:
+  template <typename T, typename... Args>
+  friend CFX_RetainPtr<T> pdfium::MakeRetain(Args&&... args);
+
+  // IFGAS_Stream
+  uint32_t GetAccessModes() const override;
+  int32_t GetLength() const override;
+  int32_t Seek(FX_STREAMSEEK eSeek, int32_t iOffset) override;
+  int32_t GetPosition() override;
+  bool IsEOF() const override;
+  int32_t ReadData(uint8_t* pBuffer, int32_t iBufferSize) override;
+  int32_t ReadString(wchar_t* pStr, int32_t iMaxLength, bool& bEOS) override;
+  int32_t WriteData(const uint8_t* pBuffer, int32_t iBufferSize) override;
+  int32_t WriteString(const wchar_t* pStr, int32_t iLength) override;
+  void Flush() override;
+  bool SetLength(int32_t iLength) override;
+  int32_t GetBOM(uint8_t bom[4]) const override;
+  uint16_t GetCodePage() const override;
+  uint16_t SetCodePage(uint16_t wCodePage) override;
+  CFX_RetainPtr<IFGAS_Stream> CreateSharedStream(uint32_t dwAccess,
+                                                 int32_t iOffset,
+                                                 int32_t iLength) override;
+
+ protected:
+  explicit CFGAS_TextStream(const CFX_RetainPtr<IFGAS_Stream>& pStream);
+  ~CFGAS_TextStream() override;
+
+  void InitStream();
+
+  uint16_t m_wCodePage;
+  int32_t m_wBOMLength;
+  uint32_t m_dwBOM;
+  uint8_t* m_pBuf;
+  int32_t m_iBufSize;
+  CFX_RetainPtr<IFGAS_Stream> m_pStreamImp;
+};
+
+class CFGAS_FileRead : public IFX_SeekableReadStream {
+ public:
+  static CFX_RetainPtr<CFGAS_FileRead> Create(
+      const CFX_RetainPtr<IFGAS_Stream>& pStream);
+
+  explicit CFGAS_FileRead(const CFX_RetainPtr<IFGAS_Stream>& pStream);
+  ~CFGAS_FileRead() override;
+
+  // IFX_SeekableReadStream
+  FX_FILESIZE GetSize() override;
+  bool ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) override;
+
+ protected:
+  CFX_RetainPtr<IFGAS_Stream> m_pStream;
+};
+
+int32_t FileLength(FXSYS_FILE* file) {
+  ASSERT(file);
+#if _FX_OS_ == _FX_WIN32_DESKTOP_ || _FX_OS_ == _FX_WIN64_
+  return _filelength(_fileno(file));
+#else
+  int32_t iPos = FXSYS_ftell(file);
+  FXSYS_fseek(file, 0, FXSYS_SEEK_END);
+  int32_t iLen = FXSYS_ftell(file);
+  FXSYS_fseek(file, iPos, FXSYS_SEEK_SET);
+  return iLen;
+#endif
+}
+
+bool FileSetSize(FXSYS_FILE* file, int32_t size) {
+  ASSERT(file);
+#if _FX_OS_ == _FX_WIN32_DESKTOP_ || _FX_OS_ == _FX_WIN64_
+  return _chsize(_fileno(file), size) == 0;
+#elif _FX_OS_ == _FX_WIN32_MOBILE_
+  HANDLE hFile = _fileno(file);
+  uint32_t dwPos = ::SetFilePointer(hFile, 0, 0, FILE_CURRENT);
+  ::SetFilePointer(hFile, size, 0, FILE_BEGIN);
+  bool bRet = ::SetEndOfFile(hFile);
+  ::SetFilePointer(hFile, (int32_t)dwPos, 0, FILE_BEGIN);
+  return bRet;
+#else
+  return false;
+#endif
+}
+
+IFGAS_StreamImp::IFGAS_StreamImp() : m_dwAccess(0) {}
+
+CFGAS_FileStreamImp::CFGAS_FileStreamImp() : m_hFile(nullptr), m_iLength(0) {}
+
+CFGAS_FileStreamImp::~CFGAS_FileStreamImp() {
+  if (m_hFile)
+    FXSYS_fclose(m_hFile);
+}
+
+bool CFGAS_FileStreamImp::LoadFile(const wchar_t* pszSrcFileName,
+                                   uint32_t dwAccess) {
+  ASSERT(!m_hFile);
+  ASSERT(pszSrcFileName && FXSYS_wcslen(pszSrcFileName) > 0);
+#if _FX_OS_ == _FX_WIN32_DESKTOP_ || _FX_OS_ == _FX_WIN32_MOBILE_ || \
+    _FX_OS_ == _FX_WIN64_
+  const wchar_t* wsMode;
+  if (dwAccess & FX_STREAMACCESS_Write) {
+    if (dwAccess & FX_STREAMACCESS_Append) {
+      wsMode = L"a+b";
+    } else if (dwAccess & FX_STREAMACCESS_Truncate) {
+      wsMode = L"w+b";
+    } else {
+      wsMode = L"r+b";
+    }
+  } else {
+    wsMode = L"rb";
+  }
+  m_hFile = FXSYS_wfopen(pszSrcFileName, wsMode);
+
+  if (!m_hFile) {
+    if (dwAccess & FX_STREAMACCESS_Write) {
+      if (dwAccess & FX_STREAMACCESS_Create)
+        m_hFile = FXSYS_wfopen(pszSrcFileName, L"w+b");
+
+      if (!m_hFile) {
+        m_hFile = FXSYS_wfopen(pszSrcFileName, L"r+b");
+        if (!m_hFile)
+          return false;
+
+        if (dwAccess & FX_STREAMACCESS_Truncate)
+          FileSetSize(m_hFile, 0);
+      }
+    } else {
+      return false;
+    }
+  }
+#else
+  const char* wsMode = "rb";
+  if (dwAccess & FX_STREAMACCESS_Write) {
+    if (dwAccess & FX_STREAMACCESS_Append) {
+      wsMode = "a+b";
+    } else if (dwAccess & FX_STREAMACCESS_Truncate) {
+      wsMode = "w+b";
+    } else {
+      wsMode = "r+b";
+    }
+  }
+  CFX_ByteString szFileName = CFX_ByteString::FromUnicode(pszSrcFileName);
+  m_hFile = FXSYS_fopen(szFileName.c_str(), wsMode);
+  if (!m_hFile) {
+    if (dwAccess & FX_STREAMACCESS_Write) {
+      if (dwAccess & FX_STREAMACCESS_Create) {
+        m_hFile = FXSYS_fopen(szFileName.c_str(), "w+b");
+      }
+      if (!m_hFile) {
+        m_hFile = FXSYS_fopen(szFileName.c_str(), "r+b");
+        if (!m_hFile) {
+          return false;
+        }
+        if (dwAccess & FX_STREAMACCESS_Truncate) {
+          FileSetSize(m_hFile, 0);
+        }
+      }
+    } else {
+      return false;
+    }
+  }
+#endif
+  SetAccessModes(dwAccess);
+  if ((dwAccess & (FX_STREAMACCESS_Write | FX_STREAMACCESS_Truncate)) ==
+      (FX_STREAMACCESS_Write | FX_STREAMACCESS_Truncate)) {
+    m_iLength = 0;
+  } else {
+    m_iLength = FileLength(m_hFile);
+  }
+  return true;
+}
+int32_t CFGAS_FileStreamImp::GetLength() const {
+  ASSERT(m_hFile);
+  return m_iLength;
+}
+int32_t CFGAS_FileStreamImp::Seek(FX_STREAMSEEK eSeek, int32_t iOffset) {
+  ASSERT(m_hFile);
+  FXSYS_fseek(m_hFile, iOffset, eSeek);
+  return FXSYS_ftell(m_hFile);
+}
+int32_t CFGAS_FileStreamImp::GetPosition() {
+  ASSERT(m_hFile);
+  return FXSYS_ftell(m_hFile);
+}
+bool CFGAS_FileStreamImp::IsEOF() const {
+  ASSERT(m_hFile);
+  return FXSYS_ftell(m_hFile) >= m_iLength;
+}
+int32_t CFGAS_FileStreamImp::ReadData(uint8_t* pBuffer, int32_t iBufferSize) {
+  ASSERT(m_hFile);
+  ASSERT(pBuffer && iBufferSize > 0);
+  return FXSYS_fread(pBuffer, 1, iBufferSize, m_hFile);
+}
+int32_t CFGAS_FileStreamImp::ReadString(wchar_t* pStr,
+                                        int32_t iMaxLength,
+                                        bool& bEOS) {
+  ASSERT(m_hFile);
+  ASSERT(pStr && iMaxLength > 0);
+  if (m_iLength <= 0) {
+    return 0;
+  }
+  int32_t iPosition = FXSYS_ftell(m_hFile);
+  int32_t iLen = std::min((m_iLength - iPosition) / 2, iMaxLength);
+  if (iLen <= 0) {
+    return 0;
+  }
+  iLen = FXSYS_fread(pStr, 2, iLen, m_hFile);
+  int32_t iCount = 0;
+  while (*pStr != L'\0' && iCount < iLen) {
+    pStr++, iCount++;
+  }
+  iPosition += iCount * 2;
+  if (FXSYS_ftell(m_hFile) != iPosition) {
+    FXSYS_fseek(m_hFile, iPosition, 0);
+  }
+  bEOS = (iPosition >= m_iLength);
+  return iCount;
+}
+int32_t CFGAS_FileStreamImp::WriteData(const uint8_t* pBuffer,
+                                       int32_t iBufferSize) {
+  ASSERT(m_hFile && (GetAccessModes() & FX_STREAMACCESS_Write) != 0);
+  ASSERT(pBuffer && iBufferSize > 0);
+  int32_t iRet = FXSYS_fwrite(pBuffer, 1, iBufferSize, m_hFile);
+  if (iRet != 0) {
+    int32_t iPos = FXSYS_ftell(m_hFile);
+    if (iPos > m_iLength) {
+      m_iLength = iPos;
+    }
+  }
+  return iRet;
+}
+int32_t CFGAS_FileStreamImp::WriteString(const wchar_t* pStr, int32_t iLength) {
+  ASSERT(m_hFile && (GetAccessModes() & FX_STREAMACCESS_Write) != 0);
+  ASSERT(pStr && iLength > 0);
+  int32_t iRet = FXSYS_fwrite(pStr, 2, iLength, m_hFile);
+  if (iRet != 0) {
+    int32_t iPos = FXSYS_ftell(m_hFile);
+    if (iPos > m_iLength) {
+      m_iLength = iPos;
+    }
+  }
+  return iRet;
+}
+void CFGAS_FileStreamImp::Flush() {
+  ASSERT(m_hFile && (GetAccessModes() & FX_STREAMACCESS_Write) != 0);
+  FXSYS_fflush(m_hFile);
+}
+bool CFGAS_FileStreamImp::SetLength(int32_t iLength) {
+  ASSERT(m_hFile && (GetAccessModes() & FX_STREAMACCESS_Write) != 0);
+  bool bRet = FileSetSize(m_hFile, iLength);
+  m_iLength = FileLength(m_hFile);
+  return bRet;
+}
+
+CFGAS_FileReadStreamImp::CFGAS_FileReadStreamImp()
+    : m_pFileRead(nullptr), m_iPosition(0), m_iLength(0) {}
+
+bool CFGAS_FileReadStreamImp::LoadFileRead(
+    const CFX_RetainPtr<IFX_SeekableReadStream>& pFileRead,
+    uint32_t dwAccess) {
+  ASSERT(!m_pFileRead && pFileRead);
+  if (dwAccess & FX_STREAMACCESS_Write)
+    return false;
+
+  m_pFileRead = pFileRead;
+  m_iLength = m_pFileRead->GetSize();
+  return true;
+}
+
+int32_t CFGAS_FileReadStreamImp::GetLength() const {
+  return m_iLength;
+}
+int32_t CFGAS_FileReadStreamImp::Seek(FX_STREAMSEEK eSeek, int32_t iOffset) {
+  switch (eSeek) {
+    case FX_STREAMSEEK_Begin:
+      m_iPosition = iOffset;
+      break;
+    case FX_STREAMSEEK_Current:
+      m_iPosition += iOffset;
+      break;
+    case FX_STREAMSEEK_End:
+      m_iPosition = m_iLength + iOffset;
+      break;
+  }
+  if (m_iPosition < 0) {
+    m_iPosition = 0;
+  } else if (m_iPosition >= m_iLength) {
+    m_iPosition = m_iLength;
+  }
+  return m_iPosition;
+}
+bool CFGAS_FileReadStreamImp::IsEOF() const {
+  return m_iPosition >= m_iLength;
+}
+int32_t CFGAS_FileReadStreamImp::ReadData(uint8_t* pBuffer,
+                                          int32_t iBufferSize) {
+  ASSERT(m_pFileRead);
+  ASSERT(pBuffer && iBufferSize > 0);
+  if (iBufferSize > m_iLength - m_iPosition) {
+    iBufferSize = m_iLength - m_iPosition;
+  }
+  if (m_pFileRead->ReadBlock(pBuffer, m_iPosition, iBufferSize)) {
+    m_iPosition += iBufferSize;
+    return iBufferSize;
+  }
+  return 0;
+}
+int32_t CFGAS_FileReadStreamImp::ReadString(wchar_t* pStr,
+                                            int32_t iMaxLength,
+                                            bool& bEOS) {
+  ASSERT(m_pFileRead);
+  ASSERT(pStr && iMaxLength > 0);
+  iMaxLength = ReadData((uint8_t*)pStr, iMaxLength * 2) / 2;
+  if (iMaxLength <= 0) {
+    return 0;
+  }
+  int32_t i = 0;
+  while (i < iMaxLength && pStr[i] != L'\0') {
+    ++i;
+  }
+  bEOS = (m_iPosition >= m_iLength) || pStr[i] == L'\0';
+  return i;
+}
+
+CFGAS_BufferReadStreamImp::CFGAS_BufferReadStreamImp()
+    : m_iPosition(0), m_iBufferSize(0) {}
+
+CFGAS_BufferReadStreamImp::~CFGAS_BufferReadStreamImp() {}
+
+bool CFGAS_BufferReadStreamImp::LoadBufferRead(
+    const CFX_RetainPtr<IFX_BufferedReadStream>& pBufferRead,
+    int32_t iFileSize,
+    uint32_t dwAccess) {
+  ASSERT(!m_pBufferRead && pBufferRead);
+  if (dwAccess & FX_STREAMACCESS_Write)
+    return false;
+
+  m_pBufferRead = pBufferRead;
+  m_iBufferSize = iFileSize;
+  if (m_iBufferSize >= 0)
+    return true;
+
+  if (!m_pBufferRead->ReadNextBlock(true))
+    return false;
+
+  m_iBufferSize = m_pBufferRead->GetBlockSize();
+  while (!m_pBufferRead->IsEOF()) {
+    m_pBufferRead->ReadNextBlock(false);
+    m_iBufferSize += m_pBufferRead->GetBlockSize();
+  }
+  return true;
+}
+int32_t CFGAS_BufferReadStreamImp::GetLength() const {
+  return m_iBufferSize;
+}
+int32_t CFGAS_BufferReadStreamImp::Seek(FX_STREAMSEEK eSeek, int32_t iOffset) {
+  int32_t iLength = GetLength();
+  switch (eSeek) {
+    case FX_STREAMSEEK_Begin:
+      m_iPosition = iOffset;
+      break;
+    case FX_STREAMSEEK_Current:
+      m_iPosition += iOffset;
+      break;
+    case FX_STREAMSEEK_End:
+      m_iPosition = iLength + iOffset;
+      break;
+  }
+  if (m_iPosition < 0) {
+    m_iPosition = 0;
+  } else if (m_iPosition >= iLength) {
+    m_iPosition = iLength;
+  }
+  return m_iPosition;
+}
+bool CFGAS_BufferReadStreamImp::IsEOF() const {
+  return m_pBufferRead ? m_pBufferRead->IsEOF() : true;
+}
+int32_t CFGAS_BufferReadStreamImp::ReadData(uint8_t* pBuffer,
+                                            int32_t iBufferSize) {
+  ASSERT(m_pBufferRead);
+  ASSERT(pBuffer && iBufferSize > 0);
+  int32_t iLength = GetLength();
+  if (m_iPosition >= iLength) {
+    return 0;
+  }
+  if (iBufferSize > iLength - m_iPosition) {
+    iBufferSize = iLength - m_iPosition;
+  }
+  uint32_t dwBlockOffset = m_pBufferRead->GetBlockOffset();
+  uint32_t dwBlockSize = m_pBufferRead->GetBlockSize();
+  if (m_iPosition < (int32_t)dwBlockOffset) {
+    if (!m_pBufferRead->ReadNextBlock(true)) {
+      return 0;
+    }
+    dwBlockOffset = m_pBufferRead->GetBlockOffset();
+    dwBlockSize = m_pBufferRead->GetBlockSize();
+  }
+  while (m_iPosition < (int32_t)dwBlockOffset ||
+         m_iPosition >= (int32_t)(dwBlockOffset + dwBlockSize)) {
+    if (m_pBufferRead->IsEOF() || !m_pBufferRead->ReadNextBlock(false)) {
+      break;
+    }
+    dwBlockOffset = m_pBufferRead->GetBlockOffset();
+    dwBlockSize = m_pBufferRead->GetBlockSize();
+  }
+  if (m_iPosition < (int32_t)dwBlockOffset ||
+      m_iPosition >= (int32_t)(dwBlockOffset + dwBlockSize)) {
+    return 0;
+  }
+  const uint8_t* pBufferTmp = m_pBufferRead->GetBlockBuffer();
+  uint32_t dwOffsetTmp = m_iPosition - dwBlockOffset;
+  uint32_t dwCopySize =
+      std::min(iBufferSize, (int32_t)(dwBlockSize - dwOffsetTmp));
+  FXSYS_memcpy(pBuffer, pBufferTmp + dwOffsetTmp, dwCopySize);
+  dwOffsetTmp = dwCopySize;
+  iBufferSize -= dwCopySize;
+  while (iBufferSize > 0) {
+    if (!m_pBufferRead->ReadNextBlock(false)) {
+      break;
+    }
+    dwBlockOffset = m_pBufferRead->GetBlockOffset();
+    dwBlockSize = m_pBufferRead->GetBlockSize();
+    pBufferTmp = m_pBufferRead->GetBlockBuffer();
+    dwCopySize = std::min((uint32_t)iBufferSize, dwBlockSize);
+    FXSYS_memcpy(pBuffer + dwOffsetTmp, pBufferTmp, dwCopySize);
+    dwOffsetTmp += dwCopySize;
+    iBufferSize -= dwCopySize;
+  }
+  m_iPosition += dwOffsetTmp;
+  return dwOffsetTmp;
+}
+int32_t CFGAS_BufferReadStreamImp::ReadString(wchar_t* pStr,
+                                              int32_t iMaxLength,
+                                              bool& bEOS) {
+  ASSERT(m_pBufferRead);
+  ASSERT(pStr && iMaxLength > 0);
+  iMaxLength = ReadData((uint8_t*)pStr, iMaxLength * 2) / 2;
+  if (iMaxLength <= 0) {
+    return 0;
+  }
+  int32_t i = 0;
+  while (i < iMaxLength && pStr[i] != L'\0') {
+    ++i;
+  }
+  bEOS = (m_iPosition >= GetLength()) || pStr[i] == L'\0';
+  return i;
+}
+CFGAS_FileWriteStreamImp::CFGAS_FileWriteStreamImp()
+    : m_pFileWrite(nullptr), m_iPosition(0) {}
+
+bool CFGAS_FileWriteStreamImp::LoadFileWrite(
+    const CFX_RetainPtr<IFX_SeekableWriteStream>& pFileWrite,
+    uint32_t dwAccess) {
+  ASSERT(!m_pFileWrite && pFileWrite);
+  if (dwAccess & FX_STREAMACCESS_Read)
+    return false;
+
+  if (dwAccess & FX_STREAMACCESS_Append)
+    m_iPosition = pFileWrite->GetSize();
+
+  m_pFileWrite = pFileWrite;
+  return true;
+}
+
+int32_t CFGAS_FileWriteStreamImp::GetLength() const {
+  if (!m_pFileWrite)
+    return 0;
+
+  return (int32_t)m_pFileWrite->GetSize();
+}
+int32_t CFGAS_FileWriteStreamImp::Seek(FX_STREAMSEEK eSeek, int32_t iOffset) {
+  int32_t iLength = GetLength();
+  switch (eSeek) {
+    case FX_STREAMSEEK_Begin:
+      m_iPosition = iOffset;
+      break;
+    case FX_STREAMSEEK_Current:
+      m_iPosition += iOffset;
+      break;
+    case FX_STREAMSEEK_End:
+      m_iPosition = iLength + iOffset;
+      break;
+  }
+  if (m_iPosition < 0) {
+    m_iPosition = 0;
+  } else if (m_iPosition >= iLength) {
+    m_iPosition = iLength;
+  }
+  return m_iPosition;
+}
+bool CFGAS_FileWriteStreamImp::IsEOF() const {
+  return m_iPosition >= GetLength();
+}
+int32_t CFGAS_FileWriteStreamImp::WriteData(const uint8_t* pBuffer,
+                                            int32_t iBufferSize) {
+  if (!m_pFileWrite) {
+    return 0;
+  }
+  if (m_pFileWrite->WriteBlock(pBuffer, m_iPosition, iBufferSize)) {
+    m_iPosition += iBufferSize;
+  }
+  return iBufferSize;
+}
+int32_t CFGAS_FileWriteStreamImp::WriteString(const wchar_t* pStr,
+                                              int32_t iLength) {
+  return WriteData((const uint8_t*)pStr, iLength * sizeof(wchar_t));
+}
+void CFGAS_FileWriteStreamImp::Flush() {
+  if (m_pFileWrite) {
+    m_pFileWrite->Flush();
+  }
+}
+CFGAS_BufferStreamImp::CFGAS_BufferStreamImp()
+    : m_pData(nullptr), m_iTotalSize(0), m_iPosition(0), m_iLength(0) {}
+
+bool CFGAS_BufferStreamImp::LoadBuffer(uint8_t* pData,
+                                       int32_t iTotalSize,
+                                       uint32_t dwAccess) {
+  ASSERT(!m_pData && pData && iTotalSize > 0);
+  SetAccessModes(dwAccess);
+  m_pData = pData;
+  m_iTotalSize = iTotalSize;
+  m_iPosition = 0;
+  m_iLength = (dwAccess & FX_STREAMACCESS_Write) != 0 ? 0 : iTotalSize;
+  return true;
+}
+int32_t CFGAS_BufferStreamImp::GetLength() const {
+  ASSERT(m_pData);
+  return m_iLength;
+}
+int32_t CFGAS_BufferStreamImp::Seek(FX_STREAMSEEK eSeek, int32_t iOffset) {
+  ASSERT(m_pData);
+  if (eSeek == FX_STREAMSEEK_Begin) {
+    m_iPosition = iOffset;
+  } else if (eSeek == FX_STREAMSEEK_Current) {
+    m_iPosition += iOffset;
+  } else if (eSeek == FX_STREAMSEEK_End) {
+    m_iPosition = m_iLength + iOffset;
+  }
+  if (m_iPosition > m_iLength) {
+    m_iPosition = m_iLength;
+  }
+  if (m_iPosition < 0) {
+    m_iPosition = 0;
+  }
+  return m_iPosition;
+}
+int32_t CFGAS_BufferStreamImp::GetPosition() {
+  ASSERT(m_pData);
+  return m_iPosition;
+}
+bool CFGAS_BufferStreamImp::IsEOF() const {
+  ASSERT(m_pData);
+  return m_iPosition >= m_iLength;
+}
+int32_t CFGAS_BufferStreamImp::ReadData(uint8_t* pBuffer, int32_t iBufferSize) {
+  ASSERT(m_pData);
+  ASSERT(pBuffer && iBufferSize > 0);
+  int32_t iLen = std::min(m_iLength - m_iPosition, iBufferSize);
+  if (iLen <= 0) {
+    return 0;
+  }
+  FXSYS_memcpy(pBuffer, m_pData + m_iPosition, iLen);
+  m_iPosition += iLen;
+  return iLen;
+}
+int32_t CFGAS_BufferStreamImp::ReadString(wchar_t* pStr,
+                                          int32_t iMaxLength,
+                                          bool& bEOS) {
+  ASSERT(m_pData);
+  ASSERT(pStr && iMaxLength > 0);
+  int32_t iLen = std::min((m_iLength - m_iPosition) / 2, iMaxLength);
+  if (iLen <= 0) {
+    return 0;
+  }
+  const wchar_t* pSrc = (const wchar_t*)(char*)(m_pData + m_iPosition);
+  int32_t iCount = 0;
+  while (*pSrc && iCount < iLen) {
+    *pStr++ = *pSrc++;
+    iCount++;
+  }
+  m_iPosition += iCount * 2;
+  bEOS = (*pSrc == L'\0') || (m_iPosition >= m_iLength);
+  return iCount;
+}
+int32_t CFGAS_BufferStreamImp::WriteData(const uint8_t* pBuffer,
+                                         int32_t iBufferSize) {
+  ASSERT(m_pData && (GetAccessModes() & FX_STREAMACCESS_Write) != 0);
+  ASSERT(pBuffer && iBufferSize > 0);
+  int32_t iLen = std::min(m_iTotalSize - m_iPosition, iBufferSize);
+  if (iLen <= 0) {
+    return 0;
+  }
+  FXSYS_memcpy(m_pData + m_iPosition, pBuffer, iLen);
+  m_iPosition += iLen;
+  if (m_iPosition > m_iLength) {
+    m_iLength = m_iPosition;
+  }
+  return iLen;
+}
+int32_t CFGAS_BufferStreamImp::WriteString(const wchar_t* pStr,
+                                           int32_t iLength) {
+  ASSERT(m_pData && (GetAccessModes() & FX_STREAMACCESS_Write) != 0);
+  ASSERT(pStr && iLength > 0);
+  int32_t iLen = std::min((m_iTotalSize - m_iPosition) / 2, iLength);
+  if (iLen <= 0) {
+    return 0;
+  }
+  FXSYS_memcpy(m_pData + m_iPosition, pStr, iLen * 2);
+  m_iPosition += iLen * 2;
+  if (m_iPosition > m_iLength) {
+    m_iLength = m_iPosition;
+  }
+  return iLen;
+}
+
+CFGAS_TextStream::CFGAS_TextStream(const CFX_RetainPtr<IFGAS_Stream>& pStream)
+    : m_wCodePage(FX_CODEPAGE_DefANSI),
+      m_wBOMLength(0),
+      m_dwBOM(0),
+      m_pBuf(nullptr),
+      m_iBufSize(0),
+      m_pStreamImp(pStream) {
+  ASSERT(m_pStreamImp);
+  InitStream();
+}
+
+CFGAS_TextStream::~CFGAS_TextStream() {
+  if (m_pBuf)
+    FX_Free(m_pBuf);
+}
+
+void CFGAS_TextStream::InitStream() {
+  int32_t iPosition = m_pStreamImp->GetPosition();
+  m_pStreamImp->Seek(FX_STREAMSEEK_Begin, 0);
+  m_pStreamImp->ReadData((uint8_t*)&m_dwBOM, 3);
+#if _FX_ENDIAN_ == _FX_LITTLE_ENDIAN_
+  m_dwBOM &= 0x00FFFFFF;
+  if (m_dwBOM == 0x00BFBBEF) {
+    m_wBOMLength = 3;
+    m_wCodePage = FX_CODEPAGE_UTF8;
+  } else {
+    m_dwBOM &= 0x0000FFFF;
+    if (m_dwBOM == 0x0000FFFE) {
+      m_wBOMLength = 2;
+      m_wCodePage = FX_CODEPAGE_UTF16BE;
+    } else if (m_dwBOM == 0x0000FEFF) {
+      m_wBOMLength = 2;
+      m_wCodePage = FX_CODEPAGE_UTF16LE;
+    } else {
+      m_wBOMLength = 0;
+      m_dwBOM = 0;
+      m_wCodePage = FXSYS_GetACP();
+    }
+  }
+#else
+  m_dwBOM &= 0xFFFFFF00;
+  if (m_dwBOM == 0xEFBBBF00) {
+    m_wBOMLength = 3;
+    m_wCodePage = FX_CODEPAGE_UTF8;
+  } else {
+    m_dwBOM &= 0xFFFF0000;
+    if (m_dwBOM == 0xFEFF0000) {
+      m_wBOMLength = 2;
+      m_wCodePage = FX_CODEPAGE_UTF16BE;
+    } else if (m_dwBOM == 0xFFFE0000) {
+      m_wBOMLength = 2;
+      m_wCodePage = FX_CODEPAGE_UTF16LE;
+    } else {
+      m_wBOMLength = 0;
+      m_dwBOM = 0;
+      m_wCodePage = FXSYS_GetACP();
+    }
+  }
+#endif
+  m_pStreamImp->Seek(FX_STREAMSEEK_Begin, std::max(m_wBOMLength, iPosition));
+}
+
+uint32_t CFGAS_TextStream::GetAccessModes() const {
+  return m_pStreamImp->GetAccessModes() | FX_STREAMACCESS_Text;
+}
+
+int32_t CFGAS_TextStream::GetLength() const {
+  return m_pStreamImp->GetLength();
+}
+
+int32_t CFGAS_TextStream::Seek(FX_STREAMSEEK eSeek, int32_t iOffset) {
+  return m_pStreamImp->Seek(eSeek, iOffset);
+}
+
+int32_t CFGAS_TextStream::GetPosition() {
+  return m_pStreamImp->GetPosition();
+}
+
+bool CFGAS_TextStream::IsEOF() const {
+  return m_pStreamImp->IsEOF();
+}
+
+int32_t CFGAS_TextStream::ReadData(uint8_t* pBuffer, int32_t iBufferSize) {
+  return m_pStreamImp->ReadData(pBuffer, iBufferSize);
+}
+
+int32_t CFGAS_TextStream::WriteData(const uint8_t* pBuffer,
+                                    int32_t iBufferSize) {
+  return m_pStreamImp->WriteData(pBuffer, iBufferSize);
+}
+
+void CFGAS_TextStream::Flush() {
+  m_pStreamImp->Flush();
+}
+
+bool CFGAS_TextStream::SetLength(int32_t iLength) {
+  return m_pStreamImp->SetLength(iLength);
+}
+
+uint16_t CFGAS_TextStream::GetCodePage() const {
+  return m_wCodePage;
+}
+
+CFX_RetainPtr<IFGAS_Stream> CFGAS_TextStream::CreateSharedStream(
+    uint32_t dwAccess,
+    int32_t iOffset,
+    int32_t iLength) {
+  CFX_RetainPtr<IFGAS_Stream> pSR =
+      m_pStreamImp->CreateSharedStream(dwAccess, iOffset, iLength);
+  if (!pSR)
+    return nullptr;
+
+  if (dwAccess & FX_STREAMACCESS_Text)
+    return pdfium::MakeRetain<CFGAS_TextStream>(pSR);
+
+  return pSR;
+}
+
+int32_t CFGAS_TextStream::GetBOM(uint8_t bom[4]) const {
+  if (m_wBOMLength < 1)
+    return 0;
+
+  *(uint32_t*)bom = m_dwBOM;
+  return m_wBOMLength;
+}
+
+uint16_t CFGAS_TextStream::SetCodePage(uint16_t wCodePage) {
+  if (m_wBOMLength > 0)
+    return m_wCodePage;
+
+  uint16_t v = m_wCodePage;
+  m_wCodePage = wCodePage;
+  return v;
+}
+
+int32_t CFGAS_TextStream::ReadString(wchar_t* pStr,
+                                     int32_t iMaxLength,
+                                     bool& bEOS) {
+  ASSERT(pStr && iMaxLength > 0);
+  if (!m_pStreamImp) {
+    return -1;
+  }
+  int32_t iLen;
+  if (m_wCodePage == FX_CODEPAGE_UTF16LE ||
+      m_wCodePage == FX_CODEPAGE_UTF16BE) {
+    int32_t iBytes = iMaxLength * 2;
+    iLen = m_pStreamImp->ReadData((uint8_t*)pStr, iBytes);
+    iMaxLength = iLen / 2;
+    if (sizeof(wchar_t) > 2) {
+      FX_UTF16ToWChar(pStr, iMaxLength);
+    }
+#if _FX_ENDIAN_ == _FX_BIG_ENDIAN_
+    if (m_wCodePage == FX_CODEPAGE_UTF16LE) {
+      FX_SwapByteOrder(pStr, iMaxLength);
+    }
+#else
+    if (m_wCodePage == FX_CODEPAGE_UTF16BE) {
+      FX_SwapByteOrder(pStr, iMaxLength);
+    }
+#endif
+  } else {
+    int32_t pos = m_pStreamImp->GetPosition();
+    int32_t iBytes = iMaxLength;
+    iBytes = std::min(iBytes, m_pStreamImp->GetLength() - pos);
+    if (iBytes > 0) {
+      if (!m_pBuf) {
+        m_pBuf = FX_Alloc(uint8_t, iBytes);
+        m_iBufSize = iBytes;
+      } else if (iBytes > m_iBufSize) {
+        m_pBuf = FX_Realloc(uint8_t, m_pBuf, iBytes);
+        m_iBufSize = iBytes;
+      }
+      iLen = m_pStreamImp->ReadData(m_pBuf, iBytes);
+      int32_t iSrc = iLen;
+      int32_t iDecode = FX_DecodeString(m_wCodePage, (const char*)m_pBuf, &iSrc,
+                                        pStr, &iMaxLength, true);
+      m_pStreamImp->Seek(FX_STREAMSEEK_Current, iSrc - iLen);
+      if (iDecode < 1) {
+        return -1;
+      }
+    } else {
+      iMaxLength = 0;
+    }
+  }
+  bEOS = m_pStreamImp->IsEOF();
+  return iMaxLength;
+}
+
+int32_t CFGAS_TextStream::WriteString(const wchar_t* pStr, int32_t iLength) {
+  ASSERT(pStr && iLength > 0);
+  if ((m_pStreamImp->GetAccessModes() & FX_STREAMACCESS_Write) == 0)
+    return -1;
+
+  if (m_wCodePage == FX_CODEPAGE_UTF8) {
+    int32_t len = iLength;
+    CFX_UTF8Encoder encoder;
+    while (len-- > 0) {
+      encoder.Input(*pStr++);
+    }
+    CFX_ByteStringC bsResult = encoder.GetResult();
+    m_pStreamImp->WriteData((const uint8_t*)bsResult.c_str(),
+                            bsResult.GetLength());
+  }
+  return iLength;
+}
+
+CFGAS_Stream::CFGAS_Stream()
+    : m_eStreamType(FX_SREAMTYPE_Unknown),
+      m_pStreamImp(nullptr),
+      m_dwAccess(0),
+      m_iTotalSize(0),
+      m_iPosition(0),
+      m_iStart(0),
+      m_iLength(0),
+      m_iRefCount(1) {}
+
+CFGAS_Stream::~CFGAS_Stream() {
+  if (m_eStreamType != FX_STREAMTYPE_Stream)
+    delete m_pStreamImp;
+}
+
+bool CFGAS_Stream::LoadFile(const wchar_t* pszSrcFileName, uint32_t dwAccess) {
+  if (m_eStreamType != FX_SREAMTYPE_Unknown || m_pStreamImp)
+    return false;
+
+  if (!pszSrcFileName || FXSYS_wcslen(pszSrcFileName) < 1)
+    return false;
+
+  std::unique_ptr<CFGAS_FileStreamImp> pImp(new CFGAS_FileStreamImp());
+  if (!pImp->LoadFile(pszSrcFileName, dwAccess))
+    return false;
+
+  m_pStreamImp = pImp.release();
+  m_eStreamType = FX_STREAMTYPE_File;
+  m_dwAccess = dwAccess;
+  m_iLength = m_pStreamImp->GetLength();
+  return true;
+}
+
+bool CFGAS_Stream::LoadFileRead(
+    const CFX_RetainPtr<IFX_SeekableReadStream>& pFileRead,
+    uint32_t dwAccess) {
+  if (m_eStreamType != FX_SREAMTYPE_Unknown || m_pStreamImp)
+    return false;
+
+  if (!pFileRead)
+    return false;
+
+  std::unique_ptr<CFGAS_FileReadStreamImp> pImp(new CFGAS_FileReadStreamImp());
+  if (!pImp->LoadFileRead(pFileRead, dwAccess))
+    return false;
+
+  m_pStreamImp = pImp.release();
+  m_eStreamType = FX_STREAMTYPE_File;
+  m_dwAccess = dwAccess;
+  m_iLength = m_pStreamImp->GetLength();
+  return true;
+}
+
+bool CFGAS_Stream::LoadFileWrite(
+    const CFX_RetainPtr<IFX_SeekableWriteStream>& pFileWrite,
+    uint32_t dwAccess) {
+  if (m_eStreamType != FX_SREAMTYPE_Unknown || m_pStreamImp)
+    return false;
+
+  if (!pFileWrite)
+    return false;
+
+  auto pImp = pdfium::MakeUnique<CFGAS_FileWriteStreamImp>();
+  if (!pImp->LoadFileWrite(pFileWrite, dwAccess))
+    return false;
+
+  m_pStreamImp = pImp.release();
+  m_eStreamType = FX_STREAMTYPE_File;
+  m_dwAccess = dwAccess;
+  m_iLength = m_pStreamImp->GetLength();
+  return true;
+}
+
+bool CFGAS_Stream::LoadBuffer(uint8_t* pData,
+                              int32_t iTotalSize,
+                              uint32_t dwAccess) {
+  if (m_eStreamType != FX_SREAMTYPE_Unknown || m_pStreamImp)
+    return false;
+
+  if (!pData || iTotalSize < 1)
+    return false;
+
+  std::unique_ptr<CFGAS_BufferStreamImp> pImp(new CFGAS_BufferStreamImp());
+  if (!pImp->LoadBuffer(pData, iTotalSize, dwAccess))
+    return false;
+
+  m_pStreamImp = pImp.release();
+  m_eStreamType = FX_STREAMTYPE_Buffer;
+  m_dwAccess = dwAccess;
+  m_iLength = m_pStreamImp->GetLength();
+  return true;
+}
+
+bool CFGAS_Stream::LoadBufferRead(
+    const CFX_RetainPtr<IFX_BufferedReadStream>& pBufferRead,
+    int32_t iFileSize,
+    uint32_t dwAccess) {
+  if (m_eStreamType != FX_SREAMTYPE_Unknown || m_pStreamImp)
+    return false;
+
+  if (!pBufferRead)
+    return false;
+
+  auto pImp = pdfium::MakeUnique<CFGAS_BufferReadStreamImp>();
+  if (!pImp->LoadBufferRead(pBufferRead, iFileSize, dwAccess))
+    return false;
+
+  m_pStreamImp = pImp.release();
+  m_eStreamType = FX_STREAMTYPE_BufferRead;
+  m_dwAccess = dwAccess;
+  m_iLength = m_pStreamImp->GetLength();
+  return true;
+}
+
+uint32_t CFGAS_Stream::GetAccessModes() const {
+  return m_dwAccess;
+}
+
+int32_t CFGAS_Stream::GetLength() const {
+  if (!m_pStreamImp) {
+    return -1;
+  }
+  if (m_eStreamType == FX_STREAMTYPE_File ||
+      m_eStreamType == FX_STREAMTYPE_Buffer) {
+    return m_pStreamImp->GetLength();
+  }
+  return m_iLength;
+}
+int32_t CFGAS_Stream::Seek(FX_STREAMSEEK eSeek, int32_t iOffset) {
+  if (!m_pStreamImp) {
+    return -1;
+  }
+  if (m_eStreamType == FX_STREAMTYPE_File ||
+      m_eStreamType == FX_STREAMTYPE_Buffer) {
+    return m_iPosition = m_pStreamImp->Seek(eSeek, iOffset);
+  }
+  int32_t iEnd = m_iStart + m_iLength;
+  int32_t iPosition = m_iStart + iOffset;
+  if (eSeek == FX_STREAMSEEK_Begin) {
+    m_iPosition = iPosition;
+  } else if (eSeek == FX_STREAMSEEK_Current) {
+    m_iPosition += iOffset;
+  } else if (eSeek == FX_STREAMSEEK_End) {
+    m_iPosition = iEnd + iOffset;
+  }
+  if (m_iPosition > iEnd) {
+    m_iPosition = iEnd;
+  }
+  if (m_iPosition < m_iStart) {
+    m_iPosition = m_iStart;
+  }
+  return m_iPosition - m_iStart;
+}
+int32_t CFGAS_Stream::GetPosition() {
+  if (!m_pStreamImp) {
+    return -1;
+  }
+  if (m_eStreamType == FX_STREAMTYPE_File ||
+      m_eStreamType == FX_STREAMTYPE_Buffer) {
+    return m_iPosition = m_pStreamImp->GetPosition();
+  }
+  return m_iPosition - m_iStart;
+}
+bool CFGAS_Stream::IsEOF() const {
+  if (!m_pStreamImp) {
+    return true;
+  }
+  if (m_eStreamType == FX_STREAMTYPE_File ||
+      m_eStreamType == FX_STREAMTYPE_Buffer) {
+    return m_pStreamImp->IsEOF();
+  }
+  return m_iPosition >= m_iStart + m_iLength;
+}
+int32_t CFGAS_Stream::ReadData(uint8_t* pBuffer, int32_t iBufferSize) {
+  ASSERT(pBuffer && iBufferSize > 0);
+  if (!m_pStreamImp) {
+    return -1;
+  }
+  int32_t iLen = std::min(m_iStart + m_iLength - m_iPosition, iBufferSize);
+  if (iLen <= 0) {
+    return 0;
+  }
+  if (m_pStreamImp->GetPosition() != m_iPosition) {
+    m_pStreamImp->Seek(FX_STREAMSEEK_Begin, m_iPosition);
+  }
+  iLen = m_pStreamImp->ReadData(pBuffer, iLen);
+  m_iPosition = m_pStreamImp->GetPosition();
+  return iLen;
+}
+int32_t CFGAS_Stream::ReadString(wchar_t* pStr,
+                                 int32_t iMaxLength,
+                                 bool& bEOS) {
+  ASSERT(pStr && iMaxLength > 0);
+  if (!m_pStreamImp) {
+    return -1;
+  }
+  int32_t iEnd = m_iStart + m_iLength;
+  int32_t iLen = iEnd - m_iPosition;
+  iLen = std::min(iEnd / 2, iMaxLength);
+  if (iLen <= 0) {
+    return 0;
+  }
+  if (m_pStreamImp->GetPosition() != m_iPosition) {
+    m_pStreamImp->Seek(FX_STREAMSEEK_Begin, m_iPosition);
+  }
+  iLen = m_pStreamImp->ReadString(pStr, iLen, bEOS);
+  m_iPosition = m_pStreamImp->GetPosition();
+  if (iLen > 0 && m_iPosition >= iEnd) {
+    bEOS = true;
+  }
+  return iLen;
+}
+
+int32_t CFGAS_Stream::WriteData(const uint8_t* pBuffer, int32_t iBufferSize) {
+  ASSERT(pBuffer && iBufferSize > 0);
+  if (!m_pStreamImp) {
+    return -1;
+  }
+  if ((m_dwAccess & FX_STREAMACCESS_Write) == 0) {
+    return -1;
+  }
+  int32_t iLen = iBufferSize;
+  if (m_eStreamType == FX_STREAMTYPE_Stream) {
+    iLen = std::min(m_iStart + m_iTotalSize - m_iPosition, iBufferSize);
+    if (iLen <= 0) {
+      return 0;
+    }
+  }
+  int32_t iEnd = m_iStart + m_iLength;
+  if (m_pStreamImp->GetPosition() != m_iPosition) {
+    m_pStreamImp->Seek(FX_STREAMSEEK_Begin, m_iPosition);
+  }
+  iLen = m_pStreamImp->WriteData(pBuffer, iLen);
+  m_iPosition = m_pStreamImp->GetPosition();
+  if (m_iPosition > iEnd) {
+    m_iLength = m_iPosition - m_iStart;
+  }
+  return iLen;
+}
+int32_t CFGAS_Stream::WriteString(const wchar_t* pStr, int32_t iLength) {
+  ASSERT(pStr && iLength > 0);
+  if (!m_pStreamImp) {
+    return -1;
+  }
+  if ((m_dwAccess & FX_STREAMACCESS_Write) == 0) {
+    return -1;
+  }
+  int32_t iLen = iLength;
+  if (m_eStreamType == FX_STREAMTYPE_Stream) {
+    iLen = std::min((m_iStart + m_iTotalSize - m_iPosition) / 2, iLength);
+    if (iLen <= 0) {
+      return 0;
+    }
+  }
+  int32_t iEnd = m_iStart + m_iLength;
+  if (m_pStreamImp->GetPosition() != m_iPosition) {
+    m_pStreamImp->Seek(FX_STREAMSEEK_Begin, m_iPosition);
+  }
+  iLen = m_pStreamImp->WriteString(pStr, iLen);
+  m_iPosition = m_pStreamImp->GetPosition();
+  if (m_iPosition > iEnd) {
+    m_iLength = m_iPosition - m_iStart;
+  }
+  return iLen;
+}
+void CFGAS_Stream::Flush() {
+  if (!m_pStreamImp) {
+    return;
+  }
+  if ((m_dwAccess & FX_STREAMACCESS_Write) == 0) {
+    return;
+  }
+  m_pStreamImp->Flush();
+}
+bool CFGAS_Stream::SetLength(int32_t iLength) {
+  if (!m_pStreamImp) {
+    return false;
+  }
+  if ((m_dwAccess & FX_STREAMACCESS_Write) == 0) {
+    return false;
+  }
+  return m_pStreamImp->SetLength(iLength);
+}
+int32_t CFGAS_Stream::GetBOM(uint8_t bom[4]) const {
+  if (!m_pStreamImp) {
+    return -1;
+  }
+  return 0;
+}
+uint16_t CFGAS_Stream::GetCodePage() const {
+#if _FX_ENDIAN_ == _FX_LITTLE_ENDIAN_
+  return FX_CODEPAGE_UTF16LE;
+#else
+  return FX_CODEPAGE_UTF16BE;
+#endif
+}
+uint16_t CFGAS_Stream::SetCodePage(uint16_t wCodePage) {
+#if _FX_ENDIAN_ == _FX_LITTLE_ENDIAN_
+  return FX_CODEPAGE_UTF16LE;
+#else
+  return FX_CODEPAGE_UTF16BE;
+#endif
+}
+
+CFX_RetainPtr<IFGAS_Stream> CFGAS_Stream::CreateSharedStream(uint32_t dwAccess,
+                                                             int32_t iOffset,
+                                                             int32_t iLength) {
+  ASSERT(iLength > 0);
+  if (!m_pStreamImp)
+    return nullptr;
+
+  if ((m_dwAccess & FX_STREAMACCESS_Text) != 0 &&
+      (dwAccess & FX_STREAMACCESS_Text) == 0) {
+    return nullptr;
+  }
+  if ((m_dwAccess & FX_STREAMACCESS_Write) == 0 &&
+      (dwAccess & FX_STREAMACCESS_Write) != 0) {
+    return nullptr;
+  }
+  int32_t iStart = m_iStart + iOffset;
+  int32_t iTotal = m_iStart + m_iLength;
+  if (iStart < m_iStart || iStart >= iTotal)
+    return nullptr;
+
+  int32_t iEnd = iStart + iLength;
+  if (iEnd < iStart || iEnd > iTotal)
+    return nullptr;
+
+  auto pShared = pdfium::MakeRetain<CFGAS_Stream>();
+  pShared->m_eStreamType = FX_STREAMTYPE_Stream;
+  pShared->m_pStreamImp = m_pStreamImp;
+  pShared->m_dwAccess = dwAccess;
+  pShared->m_iTotalSize = iLength;
+  pShared->m_iPosition = iStart;
+  pShared->m_iStart = iStart;
+  pShared->m_iLength = (dwAccess & FX_STREAMACCESS_Write) != 0 ? 0 : iLength;
+  if (dwAccess & FX_STREAMACCESS_Text)
+    return IFGAS_Stream::CreateTextStream(pShared);
+
+  return pShared;
+}
+
+CFX_RetainPtr<CFGAS_FileRead> CFGAS_FileRead::Create(
+    const CFX_RetainPtr<IFGAS_Stream>& pStream) {
+  return pdfium::MakeRetain<CFGAS_FileRead>(pStream);
+}
+
+CFGAS_FileRead::CFGAS_FileRead(const CFX_RetainPtr<IFGAS_Stream>& pStream)
+    : m_pStream(pStream) {
+  ASSERT(m_pStream);
+}
+
+CFGAS_FileRead::~CFGAS_FileRead() {}
+
+FX_FILESIZE CFGAS_FileRead::GetSize() {
+  return (FX_FILESIZE)m_pStream->GetLength();
+}
+
+bool CFGAS_FileRead::ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) {
+  m_pStream->Seek(FX_STREAMSEEK_Begin, (int32_t)offset);
+  int32_t iLen = m_pStream->ReadData((uint8_t*)buffer, (int32_t)size);
+  return iLen == (int32_t)size;
+}
+
+}  // namespace
+
+// static
+CFX_RetainPtr<IFGAS_Stream> IFGAS_Stream::CreateStream(
+    const CFX_RetainPtr<IFX_SeekableReadStream>& pFileRead,
+    uint32_t dwAccess) {
+  auto pSR = pdfium::MakeRetain<CFGAS_Stream>();
+  if (!pSR->LoadFileRead(pFileRead, dwAccess))
+    return nullptr;
+
+  if (dwAccess & FX_STREAMACCESS_Text)
+    return pdfium::MakeRetain<CFGAS_TextStream>(pSR);
+
+  return pSR;
+}
+
+// static
+CFX_RetainPtr<IFGAS_Stream> IFGAS_Stream::CreateStream(
+    const CFX_RetainPtr<IFX_SeekableWriteStream>& pFileWrite,
+    uint32_t dwAccess) {
+  auto pSR = pdfium::MakeRetain<CFGAS_Stream>();
+  if (!pSR->LoadFileWrite(pFileWrite, dwAccess))
+    return nullptr;
+
+  if (dwAccess & FX_STREAMACCESS_Text)
+    return pdfium::MakeRetain<CFGAS_TextStream>(pSR);
+
+  return pSR;
+}
+
+// static
+CFX_RetainPtr<IFGAS_Stream> IFGAS_Stream::CreateStream(uint8_t* pData,
+                                                       int32_t length,
+                                                       uint32_t dwAccess) {
+  auto pSR = pdfium::MakeRetain<CFGAS_Stream>();
+  if (!pSR->LoadBuffer(pData, length, dwAccess))
+    return nullptr;
+
+  if (dwAccess & FX_STREAMACCESS_Text)
+    return pdfium::MakeRetain<CFGAS_TextStream>(pSR);
+
+  return pSR;
+}
+
+// static
+CFX_RetainPtr<IFGAS_Stream> IFGAS_Stream::CreateTextStream(
+    const CFX_RetainPtr<IFGAS_Stream>& pBaseStream) {
+  ASSERT(pBaseStream);
+  return pdfium::MakeRetain<CFGAS_TextStream>(pBaseStream);
+}
+
+// static
+CFX_RetainPtr<IFX_SeekableReadStream> IFGAS_Stream::MakeSeekableReadStream() {
+  return CFGAS_FileRead::Create(CFX_RetainPtr<IFGAS_Stream>(this));
+}