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package org.openslx.virtualization.disk;
import java.io.RandomAccessFile;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import org.openslx.virtualization.Version;
/**
* VDI disk image for virtual machines.
*
* @author Manuel Bentele
* @version 1.0
*/
public class DiskImageVdi extends DiskImage
{
/**
* Big endian representation of the little endian VDI magic bytes (signature).
*/
private static final int VDI_MAGIC = 0x7f10dabe;
/**
* Just 16 null-bytes
*/
private static final byte[] ZERO_UUID = new byte[16];
/**
* Creates a new VDI disk image from an existing VDI image file.
*
* @param diskImage file to a VDI disk storing the image content.
*/
DiskImageVdi( RandomAccessFile diskImage )
{
super( diskImage );
}
/**
* Probe specified file with unknown format to be a VDI disk image file.
*
* @param diskImage file with unknown format that should be probed.
* @return state whether file is a VDI disk image or not.
*
* @throws DiskImageException cannot probe specified file with unknown format.
*/
public static boolean probe( RandomAccessFile diskImage ) throws DiskImageException
{
final boolean isVdiImageFormat;
// goto the beginning of the disk image to read the magic bytes
// skip first 64 bytes (opening tag)
final int diskImageMagic = DiskImageUtils.readInt( diskImage, 64 );
// check if disk image's magic bytes can be found
if ( diskImageMagic == DiskImageVdi.VDI_MAGIC ) {
isVdiImageFormat = true;
} else {
isVdiImageFormat = false;
}
return isVdiImageFormat;
}
@Override
public boolean isStandalone() throws DiskImageException
{
// VDI does not seem to support split VDI files, so VDI files are always standalone
return true;
}
@Override
public boolean isCompressed() throws DiskImageException
{
// compression is done by sparsifying the disk files, there is no flag for it
return false;
}
@Override
public boolean isSnapshot() throws DiskImageException
{
final RandomAccessFile diskFile = this.getDiskImage();
// if parent UUID is set, the VDI file is a snapshot
byte[] parentUuid = DiskImageUtils.readBytesAsArray( diskFile, 440, 16 );
return !Arrays.equals( ZERO_UUID, parentUuid );
}
@Override
public Version getVersion() throws DiskImageException
{
final RandomAccessFile diskFile = this.getDiskImage();
final short vdiVersionMajor = Short.reverseBytes( DiskImageUtils.readShort( diskFile, 68 ) );
final short vdiVersionMinor = Short.reverseBytes( DiskImageUtils.readShort( diskFile, 70 ) );
return new Version( vdiVersionMajor, vdiVersionMinor );
}
@Override
public String getDescription() throws DiskImageException
{
final RandomAccessFile diskFile = this.getDiskImage();
byte[] data = DiskImageUtils.readBytesAsArray( diskFile, 84, 256 );
// This will replace invalid chars. Maybe use CharsetDecoder and fall back to latin1 on error
return new String( data, StandardCharsets.UTF_8 );
}
@Override
public ImageFormat getFormat()
{
return ImageFormat.VDI;
}
}
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