1 files changed, 30 insertions, 0 deletions
diff --git a/fpdfsdk/cpdfsdk_customaccess.cpp b/fpdfsdk/cpdfsdk_customaccess.cpp
new file mode 100644
index 0000000000..0545ae44fa
--- /dev/null
+++ b/fpdfsdk/cpdfsdk_customaccess.cpp
@@ -0,0 +1,30 @@
+// Copyright 2018 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 "fpdfsdk/cpdfsdk_customaccess.h"
+
+CPDFSDK_CustomAccess::CPDFSDK_CustomAccess(FPDF_FILEACCESS* pFileAccess)
+    : m_FileAccess(*pFileAccess) {}
+
+FX_FILESIZE CPDFSDK_CustomAccess::GetSize() {
+  return m_FileAccess.m_FileLen;
+}
+
+bool CPDFSDK_CustomAccess::ReadBlock(void* buffer,
+                                     FX_FILESIZE offset,
+                                     size_t size) {
+  if (offset < 0)
+    return false;
+
+  FX_SAFE_FILESIZE newPos = pdfium::base::checked_cast<FX_FILESIZE>(size);
+  newPos += offset;
+  if (!newPos.IsValid() ||
+      newPos.ValueOrDie() > static_cast<FX_FILESIZE>(m_FileAccess.m_FileLen)) {
+    return false;
+  }
+  return !!m_FileAccess.m_GetBlock(m_FileAccess.m_Param, offset,
+                                   static_cast<uint8_t*>(buffer), size);
+}