Move CFGAS_Stream to CFX_SeekableStreamProxy

This CL moves the FGAS stream code into core/fxcrt and renames to
CFX_SeekableStreamProxy.

Change-Id: I6641fe0cca45a128ef3ec281b0b40f8d60296387
Reviewed-on: https://pdfium-review.googlesource.com/4311
Commit-Queue: dsinclair <dsinclair@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Nicolás Peña <npm@chromium.org>

1 files changed, 307 insertions, 0 deletions

diff --git a/core/fxcrt/cfx_seekablestreamproxy.cpp b/core/fxcrt/cfx_seekablestreamproxy.cpp
new file mode 100644
index 0000000000..fe6b8dd375
--- /dev/null
+++ b/core/fxcrt/cfx_seekablestreamproxy.cpp
@@ -0,0 +1,307 @@
+// 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/fxcrt/cfx_seekablestreamproxy.h"
+
+#if _FX_OS_ == _FX_WIN32_DESKTOP_ || _FX_OS_ == _FX_WIN32_MOBILE_ || \
+    _FX_OS_ == _FX_WIN64_
+#include <io.h>
+#endif
+
+#include <algorithm>
+#include <limits>
+#include <memory>
+#include <utility>
+#include <vector>
+
+#include "core/fxcrt/fx_codepage.h"
+#include "core/fxcrt/fx_ext.h"
+#include "third_party/base/ptr_util.h"
+#include "third_party/base/stl_util.h"
+
+namespace {
+
+// Returns {src bytes consumed, dst bytes produced}.
+std::pair<FX_STRSIZE, FX_STRSIZE> UTF8Decode(const char* pSrc,
+                                             FX_STRSIZE srcLen,
+                                             wchar_t* pDst,
+                                             FX_STRSIZE dstLen) {
+  ASSERT(pDst && dstLen > 0);
+
+  if (srcLen < 1)
+    return {0, 0};
+
+  uint32_t dwCode = 0;
+  int32_t iPending = 0;
+  FX_STRSIZE iSrcNum = 0;
+  FX_STRSIZE iDstNum = 0;
+  FX_STRSIZE iIndex = 0;
+  int32_t k = 1;
+  while (iIndex < srcLen) {
+    uint8_t byte = static_cast<uint8_t>(*(pSrc + iIndex));
+    if (byte < 0x80) {
+      iPending = 0;
+      k = 1;
+      iDstNum++;
+      iSrcNum += k;
+      *pDst++ = byte;
+      if (iDstNum >= dstLen)
+        break;
+    } else if (byte < 0xc0) {
+      if (iPending < 1)
+        break;
+
+      iPending--;
+      dwCode |= (byte & 0x3f) << (iPending * 6);
+      if (iPending == 0) {
+        iDstNum++;
+        iSrcNum += k;
+        *pDst++ = dwCode;
+        if (iDstNum >= dstLen)
+          break;
+      }
+    } else if (byte < 0xe0) {
+      iPending = 1;
+      k = 2;
+      dwCode = (byte & 0x1f) << 6;
+    } else if (byte < 0xf0) {
+      iPending = 2;
+      k = 3;
+      dwCode = (byte & 0x0f) << 12;
+    } else if (byte < 0xf8) {
+      iPending = 3;
+      k = 4;
+      dwCode = (byte & 0x07) << 18;
+    } else if (byte < 0xfc) {
+      iPending = 4;
+      k = 5;
+      dwCode = (byte & 0x03) << 24;
+    } else if (byte < 0xfe) {
+      iPending = 5;
+      k = 6;
+      dwCode = (byte & 0x01) << 30;
+    } else {
+      break;
+    }
+    iIndex++;
+  }
+  return {iSrcNum, iDstNum};
+}
+
+void UTF16ToWChar(void* pBuffer, FX_STRSIZE iLength) {
+  ASSERT(pBuffer && iLength > 0);
+
+  if (sizeof(wchar_t) == 2)
+    return;
+
+  uint16_t* pSrc = static_cast<uint16_t*>(pBuffer);
+  wchar_t* pDst = static_cast<wchar_t*>(pBuffer);
+  while (--iLength >= 0)
+    pDst[iLength] = static_cast<wchar_t>(pSrc[iLength]);
+}
+
+void SwapByteOrder(wchar_t* pStr, FX_STRSIZE iLength) {
+  ASSERT(pStr);
+
+  if (iLength < 0)
+    iLength = FXSYS_wcslen(pStr);
+
+  uint16_t wch;
+  if (sizeof(wchar_t) > 2) {
+    while (iLength-- > 0) {
+      wch = static_cast<uint16_t>(*pStr);
+      wch = (wch >> 8) | (wch << 8);
+      wch &= 0x00FF;
+      *pStr = wch;
+      ++pStr;
+    }
+    return;
+  }
+
+  while (iLength-- > 0) {
+    wch = static_cast<uint16_t>(*pStr);
+    wch = (wch >> 8) | (wch << 8);
+    *pStr = wch;
+    ++pStr;
+  }
+}
+
+}  // namespace
+
+#if _FX_ENDIAN_ == _FX_LITTLE_ENDIAN_
+#define BOM_MASK 0x00FFFFFF
+#define BOM_UTF8 0x00BFBBEF
+#define BOM_UTF16_MASK 0x0000FFFF
+#define BOM_UTF16_BE 0x0000FFFE
+#define BOM_UTF16_LE 0x0000FEFF
+#else
+#define BOM_MASK 0xFFFFFF00
+#define BOM_UTF8 0xEFBBBF00
+#define BOM_UTF16_MASK 0xFFFF0000
+#define BOM_UTF16_BE 0xFEFF0000
+#define BOM_UTF16_LE 0xFFFE0000
+#endif  // _FX_ENDIAN_ == _FX_LITTLE_ENDIAN_
+
+CFX_SeekableStreamProxy::CFX_SeekableStreamProxy(
+    const CFX_RetainPtr<IFX_SeekableStream>& stream,
+    bool isWriteStream)
+    : m_IsWriteStream(isWriteStream),
+      m_wCodePage(FX_CODEPAGE_DefANSI),
+      m_wBOMLength(0),
+      m_iPosition(0),
+      m_pStream(stream) {
+  ASSERT(m_pStream);
+
+  if (isWriteStream) {
+    m_iPosition = m_pStream->GetSize();
+    return;
+  }
+
+  FX_FILESIZE iPosition = GetPosition();
+  Seek(CFX_SeekableStreamProxy::Pos::Begin, 0);
+
+  uint32_t bom;
+  ReadData(reinterpret_cast<uint8_t*>(&bom), 3);
+
+  bom &= BOM_MASK;
+  if (bom == BOM_UTF8) {
+    m_wBOMLength = 3;
+    m_wCodePage = FX_CODEPAGE_UTF8;
+  } else {
+    bom &= BOM_UTF16_MASK;
+    if (bom == BOM_UTF16_BE) {
+      m_wBOMLength = 2;
+      m_wCodePage = FX_CODEPAGE_UTF16BE;
+    } else if (bom == BOM_UTF16_LE) {
+      m_wBOMLength = 2;
+      m_wCodePage = FX_CODEPAGE_UTF16LE;
+    } else {
+      m_wBOMLength = 0;
+      m_wCodePage = FXSYS_GetACP();
+    }
+  }
+
+  Seek(CFX_SeekableStreamProxy::Pos::Begin,
+       std::max(static_cast<FX_FILESIZE>(m_wBOMLength), iPosition));
+}
+
+CFX_SeekableStreamProxy::CFX_SeekableStreamProxy(uint8_t* data, FX_STRSIZE size)
+    : CFX_SeekableStreamProxy(IFX_MemoryStream::Create(data, size), false) {}
+
+CFX_SeekableStreamProxy::~CFX_SeekableStreamProxy() {}
+
+void CFX_SeekableStreamProxy::Seek(CFX_SeekableStreamProxy::Pos eSeek,
+                                   FX_FILESIZE iOffset) {
+  switch (eSeek) {
+    case CFX_SeekableStreamProxy::Pos::Begin:
+      m_iPosition = iOffset;
+      break;
+    case CFX_SeekableStreamProxy::Pos::Current:
+      m_iPosition += iOffset;
+      break;
+  }
+  m_iPosition =
+      pdfium::clamp(m_iPosition, static_cast<FX_FILESIZE>(0), GetLength());
+}
+
+void CFX_SeekableStreamProxy::SetCodePage(uint16_t wCodePage) {
+  if (m_wBOMLength > 0)
+    return;
+  m_wCodePage = wCodePage;
+}
+
+FX_STRSIZE CFX_SeekableStreamProxy::ReadData(uint8_t* pBuffer,
+                                             FX_STRSIZE iBufferSize) {
+  ASSERT(pBuffer && iBufferSize > 0);
+
+  if (m_IsWriteStream)
+    return -1;
+
+  iBufferSize = std::min(
+      iBufferSize, static_cast<FX_STRSIZE>(m_pStream->GetSize() - m_iPosition));
+  if (iBufferSize <= 0)
+    return 0;
+
+  if (m_pStream->ReadBlock(pBuffer, m_iPosition, iBufferSize)) {
+    pdfium::base::CheckedNumeric<FX_FILESIZE> new_pos = m_iPosition;
+    new_pos += iBufferSize;
+    if (!new_pos.IsValid())
+      return 0;
+
+    m_iPosition = new_pos.ValueOrDie();
+    return iBufferSize;
+  }
+  return 0;
+}
+
+FX_STRSIZE CFX_SeekableStreamProxy::ReadString(wchar_t* pStr,
+                                               FX_STRSIZE iMaxLength,
+                                               bool* bEOS) {
+  ASSERT(pStr && iMaxLength > 0);
+
+  if (m_IsWriteStream)
+    return -1;
+
+  if (m_wCodePage == FX_CODEPAGE_UTF16LE ||
+      m_wCodePage == FX_CODEPAGE_UTF16BE) {
+    FX_FILESIZE iBytes = iMaxLength * 2;
+    FX_STRSIZE iLen = ReadData(reinterpret_cast<uint8_t*>(pStr), iBytes);
+    iMaxLength = iLen / 2;
+    if (sizeof(wchar_t) > 2)
+      UTF16ToWChar(pStr, iMaxLength);
+
+#if _FX_ENDIAN_ == _FX_BIG_ENDIAN_
+    if (m_wCodePage == FX_CODEPAGE_UTF16LE)
+      SwapByteOrder(pStr, iMaxLength);
+#else
+    if (m_wCodePage == FX_CODEPAGE_UTF16BE)
+      SwapByteOrder(pStr, iMaxLength);
+#endif
+
+  } else {
+    FX_FILESIZE pos = GetPosition();
+    FX_STRSIZE iBytes =
+        std::min(iMaxLength, static_cast<FX_STRSIZE>(GetLength() - pos));
+
+    if (iBytes > 0) {
+      std::vector<uint8_t> buf(iBytes);
+
+      FX_STRSIZE iLen = ReadData(buf.data(), iBytes);
+      if (m_wCodePage != FX_CODEPAGE_UTF8)
+        return -1;
+
+      FX_STRSIZE iSrc = 0;
+      std::tie(iSrc, iMaxLength) = UTF8Decode(
+          reinterpret_cast<const char*>(buf.data()), iLen, pStr, iMaxLength);
+      Seek(CFX_SeekableStreamProxy::Pos::Current, iSrc - iLen);
+    } else {
+      iMaxLength = 0;
+    }
+  }
+
+  *bEOS = IsEOF();
+  return iMaxLength;
+}
+
+void CFX_SeekableStreamProxy::WriteString(const CFX_WideStringC& str) {
+  if (!m_IsWriteStream || str.GetLength() == 0 ||
+      m_wCodePage != FX_CODEPAGE_UTF8) {
+    return;
+  }
+  if (!m_pStream->WriteBlock(str.c_str(), m_iPosition,
+                             str.GetLength() * sizeof(wchar_t))) {
+    return;
+  }
+
+  pdfium::base::CheckedNumeric<FX_STRSIZE> new_pos = m_iPosition;
+  new_pos += str.GetLength() * sizeof(wchar_t);
+  if (!new_pos.IsValid()) {
+    m_iPosition = std::numeric_limits<FX_STRSIZE>::max();
+    return;
+  }
+
+  m_iPosition = new_pos.ValueOrDie();
+}