diff -r ea891871f481 -r bb5522e88ab2 misc/libphysfs/lzma/CPP/7zip/Common/OffsetStream.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/misc/libphysfs/lzma/CPP/7zip/Common/OffsetStream.cpp	Mon Apr 10 12:06:43 2017 -0400
@@ -0,0 +1,35 @@
+// OffsetStream.cpp
+
+#include "StdAfx.h"
+
+#include "Common/Defs.h"
+#include "OffsetStream.h"
+
+HRESULT COffsetOutStream::Init(IOutStream *stream, UInt64 offset)
+{
+  _offset = offset;
+  _stream = stream;
+  return _stream->Seek(offset, STREAM_SEEK_SET, NULL);
+}
+
+STDMETHODIMP COffsetOutStream::Write(const void *data, UInt32 size, UInt32 *processedSize)
+{
+  return _stream->Write(data, size, processedSize);
+}
+
+STDMETHODIMP COffsetOutStream::Seek(Int64 offset, UInt32 seekOrigin, 
+    UInt64 *newPosition)
+{
+  UInt64 absoluteNewPosition;
+  if (seekOrigin == STREAM_SEEK_SET)
+    offset += _offset;
+  HRESULT result = _stream->Seek(offset, seekOrigin, &absoluteNewPosition);
+  if (newPosition != NULL)
+    *newPosition = absoluteNewPosition - _offset;
+  return result;
+}
+
+STDMETHODIMP COffsetOutStream::SetSize(Int64 newSize)
+{
+  return _stream->SetSize(_offset + newSize);
+}