haiku/headers/private/storage/OffsetFile.h

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//----------------------------------------------------------------------
// This software is part of the OpenBeOS distribution and is covered
// by the OpenBeOS license.
//---------------------------------------------------------------------
/*!
\file OffsetFile.h
OffsetFile interface declaration.
*/
#ifndef _OFFSET_FILE_H
#define _OFFSET_FILE_H
#include <DataIO.h>
#include <File.h>
namespace BPrivate {
namespace Storage {
/*!
\class OffsetFile
\brief Provides access to a file skipping a certain amount of bytes at
the beginning.
This class implements the BPositionIO interface to provide access to the
data of a file past a certain offset. This is very handy e.g. for dealing
with resources, as they always reside at the end of a file, but may start
at arbitrary offsets.
\author <a href='mailto:bonefish@users.sf.net'>Ingo Weinhold</a>
\version 0.0.0
*/
class OffsetFile : public BPositionIO {
public:
OffsetFile();
OffsetFile(BFile *file, off_t offset);
virtual ~OffsetFile();
status_t SetTo(BFile *file, off_t offset);
void Unset();
status_t InitCheck() const;
BFile *File() const;
ssize_t ReadAt(off_t pos, void *buffer, size_t size);
ssize_t WriteAt(off_t pos, const void *buffer,
size_t size);
off_t Seek(off_t position, uint32 seekMode);
off_t Position() const;
status_t SetSize(off_t size);
status_t GetSize(off_t *size);
off_t Offset() const;
private:
BFile* fFile;
off_t fOffset;
off_t fCurrentPosition;
};
}; // namespace Storage
}; // namespace BPrivate
#endif // _OFFSET_FILE_H