diff --git a/fpdfsdk/fpdf_dataavail.cpp b/fpdfsdk/fpdf_dataavail.cpp
new file mode 100644
index 0000000..b1bc1e3
--- /dev/null
+++ b/fpdfsdk/fpdf_dataavail.cpp
@@ -0,0 +1,194 @@
+// 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 "public/fpdf_dataavail.h"
+
+#include <memory>
+#include <utility>
+
+#include "core/fpdfapi/parser/cpdf_data_avail.h"
+#include "core/fpdfapi/parser/cpdf_document.h"
+#include "core/fxcrt/cfx_retain_ptr.h"
+#include "fpdfsdk/fsdk_define.h"
+#include "public/fpdf_formfill.h"
+#include "third_party/base/ptr_util.h"
+
+// These checks are here because core/ and public/ cannot depend on each other.
+static_assert(CPDF_DataAvail::DataError == PDF_DATA_ERROR,
+              "CPDF_DataAvail::DataError value mismatch");
+static_assert(CPDF_DataAvail::DataNotAvailable == PDF_DATA_NOTAVAIL,
+              "CPDF_DataAvail::DataNotAvailable value mismatch");
+static_assert(CPDF_DataAvail::DataAvailable == PDF_DATA_AVAIL,
+              "CPDF_DataAvail::DataAvailable value mismatch");
+
+static_assert(CPDF_DataAvail::LinearizationUnknown == PDF_LINEARIZATION_UNKNOWN,
+              "CPDF_DataAvail::LinearizationUnknown value mismatch");
+static_assert(CPDF_DataAvail::NotLinearized == PDF_NOT_LINEARIZED,
+              "CPDF_DataAvail::NotLinearized value mismatch");
+static_assert(CPDF_DataAvail::Linearized == PDF_LINEARIZED,
+              "CPDF_DataAvail::Linearized value mismatch");
+
+static_assert(CPDF_DataAvail::FormError == PDF_FORM_ERROR,
+              "CPDF_DataAvail::FormError value mismatch");
+static_assert(CPDF_DataAvail::FormNotAvailable == PDF_FORM_NOTAVAIL,
+              "CPDF_DataAvail::FormNotAvailable value mismatch");
+static_assert(CPDF_DataAvail::FormAvailable == PDF_FORM_AVAIL,
+              "CPDF_DataAvail::FormAvailable value mismatch");
+static_assert(CPDF_DataAvail::FormNotExist == PDF_FORM_NOTEXIST,
+              "CPDF_DataAvail::FormNotExist value mismatch");
+
+namespace {
+
+class CFPDF_FileAvailWrap : public CPDF_DataAvail::FileAvail {
+ public:
+  CFPDF_FileAvailWrap() : m_pfileAvail(nullptr) {}
+  ~CFPDF_FileAvailWrap() override {}
+
+  void Set(FX_FILEAVAIL* pfileAvail) { m_pfileAvail = pfileAvail; }
+
+  // CPDF_DataAvail::FileAvail:
+  bool IsDataAvail(FX_FILESIZE offset, uint32_t size) override {
+    return !!m_pfileAvail->IsDataAvail(m_pfileAvail, offset, size);
+  }
+
+ private:
+  FX_FILEAVAIL* m_pfileAvail;
+};
+
+class CFPDF_FileAccessWrap : public IFX_SeekableReadStream {
+ public:
+  static CFX_RetainPtr<CFPDF_FileAccessWrap> Create() {
+    return CFX_RetainPtr<CFPDF_FileAccessWrap>(new CFPDF_FileAccessWrap());
+  }
+  ~CFPDF_FileAccessWrap() override {}
+
+  void Set(FPDF_FILEACCESS* pFile) { m_pFileAccess = pFile; }
+
+  // IFX_SeekableReadStream
+  FX_FILESIZE GetSize() override { return m_pFileAccess->m_FileLen; }
+
+  bool ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) override {
+    return !!m_pFileAccess->m_GetBlock(m_pFileAccess->m_Param, offset,
+                                       (uint8_t*)buffer, size);
+  }
+
+ private:
+  CFPDF_FileAccessWrap() : m_pFileAccess(nullptr) {}
+
+  FPDF_FILEACCESS* m_pFileAccess;
+};
+
+class CFPDF_DownloadHintsWrap : public CPDF_DataAvail::DownloadHints {
+ public:
+  explicit CFPDF_DownloadHintsWrap(FX_DOWNLOADHINTS* pDownloadHints) {
+    m_pDownloadHints = pDownloadHints;
+  }
+  ~CFPDF_DownloadHintsWrap() override {}
+
+ public:
+  // IFX_DownloadHints
+  void AddSegment(FX_FILESIZE offset, uint32_t size) override {
+    m_pDownloadHints->AddSegment(m_pDownloadHints, offset, size);
+  }
+
+ private:
+  FX_DOWNLOADHINTS* m_pDownloadHints;
+};
+
+class CFPDF_DataAvail {
+ public:
+  CFPDF_DataAvail()
+      : m_FileAvail(new CFPDF_FileAvailWrap),
+        m_FileRead(CFPDF_FileAccessWrap::Create()) {}
+  ~CFPDF_DataAvail() {}
+
+  std::unique_ptr<CPDF_DataAvail> m_pDataAvail;
+  std::unique_ptr<CFPDF_FileAvailWrap> m_FileAvail;
+  CFX_RetainPtr<CFPDF_FileAccessWrap> m_FileRead;
+};
+
+CFPDF_DataAvail* CFPDFDataAvailFromFPDFAvail(FPDF_AVAIL avail) {
+  return static_cast<CFPDF_DataAvail*>(avail);
+}
+
+}  // namespace
+
+DLLEXPORT FPDF_AVAIL STDCALL FPDFAvail_Create(FX_FILEAVAIL* file_avail,
+                                              FPDF_FILEACCESS* file) {
+  CFPDF_DataAvail* pAvail = new CFPDF_DataAvail;
+  pAvail->m_FileAvail->Set(file_avail);
+  pAvail->m_FileRead->Set(file);
+  pAvail->m_pDataAvail = pdfium::MakeUnique<CPDF_DataAvail>(
+      pAvail->m_FileAvail.get(), pAvail->m_FileRead, true);
+  return pAvail;
+}
+
+DLLEXPORT void STDCALL FPDFAvail_Destroy(FPDF_AVAIL avail) {
+  delete (CFPDF_DataAvail*)avail;
+}
+
+DLLEXPORT int STDCALL FPDFAvail_IsDocAvail(FPDF_AVAIL avail,
+                                           FX_DOWNLOADHINTS* hints) {
+  if (!avail || !hints)
+    return PDF_DATA_ERROR;
+  CFPDF_DownloadHintsWrap hints_wrap(hints);
+  return CFPDFDataAvailFromFPDFAvail(avail)->m_pDataAvail->IsDocAvail(
+      &hints_wrap);
+}
+
+DLLEXPORT FPDF_DOCUMENT STDCALL
+FPDFAvail_GetDocument(FPDF_AVAIL avail, FPDF_BYTESTRING password) {
+  CFPDF_DataAvail* pDataAvail = static_cast<CFPDF_DataAvail*>(avail);
+  if (!pDataAvail)
+    return nullptr;
+
+  std::unique_ptr<CPDF_Parser> pParser(new CPDF_Parser);
+  pParser->SetPassword(password);
+
+  std::unique_ptr<CPDF_Document> pDocument(
+      new CPDF_Document(std::move(pParser)));
+  CPDF_Parser::Error error = pDocument->GetParser()->StartLinearizedParse(
+      pDataAvail->m_pDataAvail->GetFileRead(), pDocument.get());
+  if (error != CPDF_Parser::SUCCESS) {
+    ProcessParseError(error);
+    return nullptr;
+  }
+  pDataAvail->m_pDataAvail->SetDocument(pDocument.get());
+  CheckUnSupportError(pDocument.get(), FPDF_ERR_SUCCESS);
+  return FPDFDocumentFromCPDFDocument(pDocument.release());
+}
+
+DLLEXPORT int STDCALL FPDFAvail_GetFirstPageNum(FPDF_DOCUMENT doc) {
+  CPDF_Document* pDoc = CPDFDocumentFromFPDFDocument(doc);
+  return pDoc ? pDoc->GetParser()->GetFirstPageNo() : 0;
+}
+
+DLLEXPORT int STDCALL FPDFAvail_IsPageAvail(FPDF_AVAIL avail,
+                                            int page_index,
+                                            FX_DOWNLOADHINTS* hints) {
+  if (!avail || !hints)
+    return PDF_DATA_ERROR;
+  if (page_index < 0)
+    return PDF_DATA_NOTAVAIL;
+  CFPDF_DownloadHintsWrap hints_wrap(hints);
+  return CFPDFDataAvailFromFPDFAvail(avail)->m_pDataAvail->IsPageAvail(
+      page_index, &hints_wrap);
+}
+
+DLLEXPORT int STDCALL FPDFAvail_IsFormAvail(FPDF_AVAIL avail,
+                                            FX_DOWNLOADHINTS* hints) {
+  if (!avail || !hints)
+    return PDF_FORM_ERROR;
+  CFPDF_DownloadHintsWrap hints_wrap(hints);
+  return CFPDFDataAvailFromFPDFAvail(avail)->m_pDataAvail->IsFormAvail(
+      &hints_wrap);
+}
+
+DLLEXPORT int STDCALL FPDFAvail_IsLinearized(FPDF_AVAIL avail) {
+  if (!avail)
+    return PDF_LINEARIZATION_UNKNOWN;
+  return CFPDFDataAvailFromFPDFAvail(avail)->m_pDataAvail->IsLinearizedPDF();
+}