diff --git a/src/apps/bin/makeudfimage/ExtentStream.cpp b/src/apps/bin/makeudfimage/ExtentStream.cpp
new file mode 100644
index 0000000000..a3e43bcfd8
--- /dev/null
+++ b/src/apps/bin/makeudfimage/ExtentStream.cpp
@@ -0,0 +1,77 @@
+//----------------------------------------------------------------------
+//  This software is part of the OpenBeOS distribution and is covered 
+//  by the OpenBeOS license.
+//
+//  Copyright (c) 2003 Tyler Dauwalder, tyler@dauwalder.net
+//----------------------------------------------------------------------
+
+/*! \file ExtentStream.cpp
+*/
+
+#include "ExtentStream.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+ExtentStream::ExtentStream(DataStream &stream,
+                           const std::list<Udf::extent_address> &extentList,
+                           uint32 blockSize)
+	: SimulatedStream(stream)
+	, fExtentList(extentList)
+	, fBlockSize(blockSize)
+	, fSize(0)
+{
+	for (std::list<Udf::extent_address>::const_iterator i = fExtentList.begin();
+	       i != fExtentList.end();
+	         i++)
+	{
+		fSize += i->length();
+	}
+}
+
+/*! \brief Returns the largest extent in the underlying data stream
+	corresponding to the extent starting at byte position \a pos of
+	byte length \a size in the output parameter \a extent.
+	
+	NOTE: If the position is at or beyond the end of the stream, the
+	function will return B_OK, but the value of extent.size will be 0.
+*/
+status_t
+ExtentStream::_GetExtent(off_t pos, size_t size, data_extent &extent)
+{
+	status_t error = pos >= 0 ? B_OK : B_BAD_VALUE;
+	if (!error) {
+		off_t finalOffset = 0;
+		off_t streamPos = 0;
+		for (std::list<Udf::extent_address>::const_iterator i = fExtentList.begin();
+		       i != fExtentList.end();
+		         i++)
+		{
+			off_t offset = i->location() * fBlockSize;
+			finalOffset = offset + i->length();
+			if (streamPos <= pos && pos < streamPos+i->length()) {
+				// Found it
+				off_t difference = pos - streamPos;
+				extent.offset = offset + difference;
+				extent.size = i->length() - difference;
+				if (extent.size > size)
+					extent.size = size;
+				return B_OK;
+			} else {
+				streamPos += i->length();
+			}
+		}
+		// Didn't find it, so pos is past the end of the stream
+		extent.offset = finalOffset;
+		extent.size = 0;
+	}
+	return error;
+}	
+
+/*! \brief Returns the current size of the stream.
+*/
+off_t
+ExtentStream::_Size()
+{
+	return fSize;
+}
diff --git a/src/apps/bin/makeudfimage/ExtentStream.h b/src/apps/bin/makeudfimage/ExtentStream.h
new file mode 100644
index 0000000000..b7707bb4da
--- /dev/null
+++ b/src/apps/bin/makeudfimage/ExtentStream.h
@@ -0,0 +1,36 @@
+//----------------------------------------------------------------------
+//  This software is part of the OpenBeOS distribution and is covered 
+//  by the OpenBeOS license.
+//
+//  Copyright (c) 2003 Tyler Dauwalder, tyler@dauwalder.net
+//----------------------------------------------------------------------
+
+/*! \file ExtentStream.h
+*/
+
+#ifndef _EXTENT_STREAM_H
+#define _EXTENT_STREAM_H
+
+#include <list>
+
+#include "SimulatedStream.h"
+#include "UdfStructures.h"
+
+/*! \brief AbstractExtentStream implementation that takes a list of
+	block-aligned data extents.
+*/
+class ExtentStream : public SimulatedStream {
+public:
+	ExtentStream(DataStream &stream, const std::list<Udf::extent_address> &extentList, uint32 blockSize);
+
+protected:
+	virtual status_t _GetExtent(off_t pos, size_t size, data_extent &extent);
+	virtual off_t _Size();
+
+private:
+	const std::list<Udf::extent_address> &fExtentList;
+	const uint32 fBlockSize;
+	off_t fSize;
+};
+
+#endif	// _EXTENT_STREAM_H