superblock.java

来自「纯java操作系统jnode,安装简单和操作简单的个人使用的Java操作系统」· Java 代码 · 共 248 行

/*
 * $Id: Superblock.java,v 1.3 2003/12/26 08:11:03 epr Exp $
 */
package org.jnode.fs.ext2;

import org.jnode.fs.FileSystemException;

/**
 * Ext2fs superblock
 * 
 * @author Andras Nagy
 */
public class Superblock {
	public static final int SUPERBLOCK_LENGTH = 1024;
		
	private byte data[];
	
	public Superblock(byte src[]) throws FileSystemException {
		data = new byte[src.length];
		System.arraycopy(src, 0, data, 0, src.length);
			
		//check the magic :)
		if(getMagic() != 0xEF53)
			throw new FileSystemException("Not ext2 superblock ("+getMagic()+": bad magic)");
	}
	
	public long getINodesCount() {
		return Ext2Utils.get32(data, 0);
	}
	
	public long getBlocksCount() {
		return Ext2Utils.get32(data, 4);
	}
	
	public long getRBlocksCount() {
		return Ext2Utils.get32(data, 8);
	}

	public long getFreeBlocksCount() {
		return Ext2Utils.get32(data, 12);
	}

	public long getFreeInodesCount() {
		return Ext2Utils.get32(data, 16);
	}

	public long getFirstDataBlock() {
		return Ext2Utils.get32(data, 20);
	}

	private long getLogBlockSize() {
		return Ext2Utils.get32(data, 24);
	}
	
	public int getBlockSize() {
		return 1024 << getLogBlockSize();
	}

	private long getLogFragSize() {
		return Ext2Utils.get32(data, 28);
	}
	
	public int getFragSize() {
		if(getLogFragSize()>0)
			return 1024 << getLogFragSize();
		else
			return 1024 >> -getLogFragSize();
	}

	public long getBlocksPerGroup() {
		return Ext2Utils.get32(data, 32);
	}

	public long getFragsPerGroup() {
		return Ext2Utils.get32(data, 36);
	}

	public long getINodesPerGroup() {
		return Ext2Utils.get32(data, 40);
	}

	public long getMTime() {
		return Ext2Utils.get32(data, 44);
	}

	public long getWTime() {
		return Ext2Utils.get32(data, 48);
	}
	
	public int getMntCount() {
		return Ext2Utils.get16(data, 52);
	}
	
	public int getMaxMntCount() {
		return Ext2Utils.get16(data, 54);
	}

	public int getMagic() {
		return Ext2Utils.get16(data, 56);
	}
		
	public int getState() {
		return Ext2Utils.get16(data, 58);
	}

	public int getErrors() {
		return Ext2Utils.get16(data, 60);
	}

	public int getMinorRevLevel() {
		return Ext2Utils.get16(data, 62);
	}
	
	public long getLastCheck() {
		return Ext2Utils.get32(data, 64);
	}
	
	public long getCheckInterval() {
		return Ext2Utils.get32(data, 68);
	}
	
	public long getCreatorOS() {
		return Ext2Utils.get32(data, 72);
	}
	
	public long getRevLevel() {
		return Ext2Utils.get32(data, 76);
	}
	
	public int getDefResuid() {
		return Ext2Utils.get16(data, 80);
	}
	
	public int getDefResgid() {
		return Ext2Utils.get16(data, 82);
	}

	public long getFirstInode() {
		if(getRevLevel()==Ext2Constants.EXT2_DYNAMIC_REV)
			return Ext2Utils.get32(data, 84);
		else 
			return 11;
	}
			
	public long getINodeSize() {
		if(getRevLevel()==Ext2Constants.EXT2_DYNAMIC_REV)
			return Ext2Utils.get16(data, 88);
		else 
			return 128;
	}

	//XXX what to return for old versions?
	public long getBlockGroupNr() {
		if(getRevLevel()==Ext2Constants.EXT2_DYNAMIC_REV)
			return Ext2Utils.get16(data, 90);
		else 
			return 0;
	}
	
	public long getFeatureCompat() {
		if(getRevLevel()==Ext2Constants.EXT2_DYNAMIC_REV)
			return Ext2Utils.get32(data, 92);
		else 
			return 0;
	}

	public long getFeatureIncompat() {
		if(getRevLevel()==Ext2Constants.EXT2_DYNAMIC_REV)
			return Ext2Utils.get32(data, 96);
		else 
			return 0;
	}
	
	public long getFeatureROCompat() {
		if(getRevLevel()==Ext2Constants.EXT2_DYNAMIC_REV)
			return Ext2Utils.get32(data, 100);
		else 
			return 0;
	}

	public byte[] getUUID() {
		byte[] result=new byte[16];	
		if(getRevLevel()==Ext2Constants.EXT2_DYNAMIC_REV)
			System.arraycopy(data, 104, result, 0, 16);
		return result;
	}
	
	public String getVolumeName() {
		StringBuffer result=new StringBuffer();
		if(getRevLevel()==Ext2Constants.EXT2_DYNAMIC_REV)
			for(int i=0; i<16; i++) {
				char c=(char)data[120+i];
				if(c!=0)
					result.append(c);
				else
					break;
			}	
		return result.toString();
	}
	
	public String getLastMounted() {
		StringBuffer result=new StringBuffer();
		if(getRevLevel()==Ext2Constants.EXT2_DYNAMIC_REV)
			for(int i=0; i<64; i++) {
				char c=(char)data[136+i];
				if(c!=0)
					result.append(c);
				else
					break;
			}	
		return result.toString();
	}

	//not sure this is the correct byte-order for this field
	public long getAlgoBitmap() {
		if(getRevLevel()==Ext2Constants.EXT2_DYNAMIC_REV)
			return Ext2Utils.get32(data, 200);
		else 
			return 11;
	}
	
	public int getPreallocBlocks() {
		return Ext2Utils.get8(data, 204);
	}

	public int getPreallocDirBlocks() {
		return Ext2Utils.get8(data, 205);
	}

	public byte[] getJournalUUID() {
		byte[] result=new byte[16];	
		System.arraycopy(data, 208, result, 0, 16);
		return result;
	}
	
	public long getJournalINum() {
		return Ext2Utils.get32(data, 224);
	}

	public long getJournalDev() {
		return Ext2Utils.get32(data, 228);
	}

	public long getLastOrphan() {
		return Ext2Utils.get8(data, 232);
	}
}