Refactor disk image representation and add unit tests

1 files changed, 119 insertions, 0 deletions

diff --git a/src/main/java/org/openslx/vm/disk/DiskImageVdi.java b/src/main/java/org/openslx/vm/disk/DiskImageVdi.java
new file mode 100644
index 0000000..1c34c1d
--- /dev/null
+++ b/src/main/java/org/openslx/vm/disk/DiskImageVdi.java
@@ -0,0 +1,119 @@
+package org.openslx.vm.disk;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.RandomAccessFile;
+
+/**
+ * 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;
+
+	/**
+	 * Creates a new VDI disk image from an existing VDI image file.
+	 * 
+	 * @param diskImage file to a VDI disk storing the image content.
+	 * 
+	 * @throws FileNotFoundException cannot find specified VDI disk image file.
+	 * @throws IOException cannot access the content of the VDI disk image file.
+	 */
+	public DiskImageVdi( File diskImage ) throws FileNotFoundException, IOException
+	{
+		super( diskImage );
+	}
+
+	/**
+	 * Creates a new VDI disk image from an existing VDI image file.
+	 * 
+	 * @param diskImage file to a VDI disk storing the image content.
+	 */
+	public 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
+		final String parentUuid = DiskImageUtils.readBytesAsString( diskFile, 440, 16 );
+		final String zeroUuid = new String( new byte[ 16 ] );
+
+		return !zeroUuid.equals( parentUuid );
+	}
+
+	@Override
+	public int 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 DiskImageUtils.versionFromMajorMinor( vdiVersionMajor, vdiVersionMinor );
+	}
+
+	@Override
+	public String getDescription() throws DiskImageException
+	{
+		final RandomAccessFile diskFile = this.getDiskImage();
+		return DiskImageUtils.readBytesAsString( diskFile, 84, 256 );
+	}
+
+	@Override
+	public ImageFormat getFormat()
+	{
+		return ImageFormat.VDI;
+	}
+}