Add private BDataPositionIOWrapper

Implements the BPositionIO interface on top of a BDataIO, requiring the
{Read,Write}At() accesses to be sequential.

headers/build/private/support/DataPositionIOWrapper.h

@@ -0,0 +1 @@
+#include <../private/support/DataPositionIOWrapper.h>

headers/private/support/DataPositionIOWrapper.h

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2014, Ingo Weinhold, [email protected].
+ * Distributed under the terms of the MIT License.
+ */
+#ifndef _DATA_POSITION_IO_WRAPPER_H_
+#define _DATA_POSITION_IO_WRAPPER_H_
+
+
+#include <DataIO.h>
+
+
+class BDataPositionIOWrapper : public BPositionIO {
+public:
+								BDataPositionIOWrapper(BDataIO* io);
+								~BDataPositionIOWrapper();
+
+	virtual	ssize_t				Read(void* buffer, size_t size);
+	virtual	ssize_t				Write(const void* buffer, size_t size);
+
+	virtual	ssize_t				ReadAt(off_t position, void* buffer,
+									size_t size);
+	virtual	ssize_t				WriteAt(off_t position, const void* buffer,
+									size_t size);
+
+	virtual	off_t				Seek(off_t position, uint32 seekMode);
+	virtual	off_t				Position() const;
+
+	virtual	status_t			SetSize(off_t size);
+	virtual	status_t			GetSize(off_t* size) const;
+
+private:
+				BDataIO*		fIO;
+				off_t			fPosition;
+};
+
+
+#endif	// _DATA_POSITION_IO_WRAPPER_H_

src/build/libbe/support/Jamfile

@@ -12,6 +12,7 @@ BuildPlatformMergeObjectPIC <libbe_build>support_kit.o :
 	ByteOrder.cpp
 	CompressionAlgorithm.cpp
 	DataIO.cpp
+	DataPositionIOWrapper.cpp
 	Flattenable.cpp
 	List.cpp
 	Locker.cpp

src/kits/support/DataPositionIOWrapper.cpp

@@ -0,0 +1,103 @@
+/*
+ * Copyright 2014, Ingo Weinhold, [email protected].
+ * Distributed under the terms of the MIT License.
+ */
+
+
+#include <DataPositionIOWrapper.h>
+
+#include <stdio.h>
+
+
+BDataPositionIOWrapper::BDataPositionIOWrapper(BDataIO* io)
+	:
+	BPositionIO(),
+	fIO(io),
+	fPosition(0)
+{
+}
+
+
+BDataPositionIOWrapper::~BDataPositionIOWrapper()
+{
+}
+
+
+ssize_t
+BDataPositionIOWrapper::Read(void* buffer, size_t size)
+{
+	ssize_t bytesRead = fIO->Read(buffer, size);
+	if (bytesRead > 0)
+		fPosition += bytesRead;
+
+	return bytesRead;
+}
+
+
+ssize_t
+BDataPositionIOWrapper::Write(const void* buffer, size_t size)
+{
+	ssize_t bytesWritten = fIO->Write(buffer, size);
+	if (bytesWritten > 0)
+		fPosition += bytesWritten;
+
+	return bytesWritten;
+}
+
+
+ssize_t
+BDataPositionIOWrapper::ReadAt(off_t position, void* buffer, size_t size)
+{
+	if (position != fPosition)
+		return B_NOT_SUPPORTED;
+
+	return Read(buffer, size);
+}
+
+
+ssize_t
+BDataPositionIOWrapper::WriteAt(off_t position, const void* buffer,
+	size_t size)
+{
+	if (position != fPosition)
+		return B_NOT_SUPPORTED;
+
+	return Write(buffer, size);
+}
+
+
+off_t
+BDataPositionIOWrapper::Seek(off_t position, uint32 seekMode)
+{
+	switch (seekMode) {
+		case SEEK_CUR:
+			return position == 0 ? B_OK : B_NOT_SUPPORTED;
+		case SEEK_SET:
+			return position == fPosition ? B_OK : B_NOT_SUPPORTED;
+		case SEEK_END:
+			return B_NOT_SUPPORTED;
+		default:
+			return B_BAD_VALUE;
+	}
+}
+
+
+off_t
+BDataPositionIOWrapper::Position() const
+{
+	return fPosition;
+}
+
+
+status_t
+BDataPositionIOWrapper::SetSize(off_t size)
+{
+	return size == fPosition ? B_OK : B_NOT_SUPPORTED;
+}
+
+
+status_t
+BDataPositionIOWrapper::GetSize(off_t* size) const
+{
+	return B_NOT_SUPPORTED;
+}

src/kits/support/Jamfile

@@ -26,6 +26,7 @@ for architectureObject in [ MultiArchSubDirSetup ] {
 			ByteOrder.cpp
 			CompressionAlgorithm.cpp
 			DataIO.cpp
+			DataPositionIOWrapper.cpp
 			DateTime.cpp
 			Flattenable.cpp
 			List.cpp