src/com/apocalyptech/minecraft/xray/RegionFile.java - minecraft/minecraftxray - Rivoreo Source Code Repositories

 /*
  ** 2011 January 5
  **
  ** The author disclaims copyright to this source code.  In place of
  ** a legal notice, here is a blessing:
  **
  **    May you do good and not evil.
  **    May you find forgiveness for yourself and forgive others.
  **    May you share freely, never taking more than you give.
  **/

 /*
  * 2011 February 16
  *
  * This source code is based on the work of Scaevolus (see notice above).
  * It has been slightly modified by Mojang AB (constants instead of magic
  * numbers, a chunk timestamp header, and auto-formatted according to our
  * formatter template).
  *
  */

 /*
  * 2011 February 20
  *
  * Imported by CJ Kucera into X-Ray, from a blog post by Jens Bergensten
  * at: http://mojang.com/2011/02/16/minecraft-save-file-format-in-beta-1-3/
  */

 // Interfaces with region files on the disk

 /*

  Region File Format

  Concept: The minimum unit of storage on hard drives is 4KB. 90% of Minecraft
  chunks are smaller than 4KB. 99% are smaller than 8KB. Write a simple
  container to store chunks in single files in runs of 4KB sectors.

  Each region file represents a 32x32 group of chunks. The conversion from
  chunk number to region number is floor(coord / 32): a chunk at (30, -3)
  would be in region (0, -1), and one at (70, -30) would be at (3, -1).
  Region files are named "r.x.z.data", where x and z are the region coordinates.

  A region file begins with a 4KB header that describes where chunks are stored
  in the file. A 4-byte big-endian integer represents sector offsets and sector
  counts. The chunk offset for a chunk (x, z) begins at byte 4*(x+z*32) in the
  file. The bottom byte of the chunk offset indicates the number of sectors the
  chunk takes up, and the top 3 bytes represent the sector number of the chunk.
  Given a chunk offset o, the chunk data begins at byte 4096*(o/256) and takes up
  at most 4096*(o%256) bytes. A chunk cannot exceed 1MB in size. If a chunk
  offset is 0, the corresponding chunk is not stored in the region file.

  Chunk data begins with a 4-byte big-endian integer representing the chunk data
  length in bytes, not counting the length field. The length must be smaller than
  4096 times the number of sectors. The next byte is a version field, to allow
  backwards-compatible updates to how chunks are encoded.

  A version of 1 represents a gzipped NBT file. The gzipped data is the chunk
  length - 1.

  A version of 2 represents a deflated (zlib compressed) NBT file. The deflated
  data is the chunk length - 1.

  */
 package com.apocalyptech.minecraft.xray;

 import java.io.*;
 import java.util.ArrayList;
 import java.util.zip.*;

 public class RegionFile {

     private static final int VERSION_GZIP = 1;
     private static final int VERSION_DEFLATE = 2;

     private static final int SECTOR_BYTES = 4096;
     private static final int SECTOR_INTS = SECTOR_BYTES / 4;

     static final int CHUNK_HEADER_SIZE = 5;
     //private static final byte emptySector[] = new byte[4096];

     private final File fileName;
     private RandomAccessFile file;
     private final int offsets[];
     private final int chunkTimestamps[];
     private ArrayList<Boolean> sectorFree;
     private int sizeDelta;
     private long lastModified = 0;

     public RegionFile(File path) {
         offsets = new int[SECTOR_INTS];
         chunkTimestamps = new int[SECTOR_INTS];

         fileName = path;
         debugln("REGION LOAD " + fileName);

         sizeDelta = 0;

         try {
             if (path.exists()) {
                 lastModified = path.lastModified();
             }

             file = new RandomAccessFile(path, "r");

             if (file.length() < SECTOR_BYTES) {
                 /* we need to write the chunk offset table */
                 for (int i = 0; i < SECTOR_INTS; ++i) {
                     file.writeInt(0);
                 }
                 // write another sector for the timestamp info
                 for (int i = 0; i < SECTOR_INTS; ++i) {
                     file.writeInt(0);
                 }

                 sizeDelta += SECTOR_BYTES * 2;
             }

             if ((file.length() & 0xfff) != 0) {
                 /* the file size is not a multiple of 4KB, grow it */
                 for (int i = 0; i < (file.length() & 0xfff); ++i) {
                     file.write((byte) 0);
                 }
             }

             /* set up the available sector map */
             int nSectors = (int) file.length() / SECTOR_BYTES;
             sectorFree = new ArrayList<Boolean>(nSectors);

             for (int i = 0; i < nSectors; ++i) {
                 sectorFree.add(true);
             }

             sectorFree.set(0, false); // chunk offset table
             sectorFree.set(1, false); // for the last modified info

             file.seek(0);
             for (int i = 0; i < SECTOR_INTS; ++i) {
                 int offset = file.readInt();
                 offsets[i] = offset;
                 if (offset != 0 && (offset >> 8) + (offset & 0xFF) <= sectorFree.size()) {
                     for (int sectorNum = 0; sectorNum < (offset & 0xFF); ++sectorNum) {
                         sectorFree.set((offset >> 8) + sectorNum, false);
                     }
                 }
             }
             for (int i = 0; i < SECTOR_INTS; ++i) {
                 int lastModValue = file.readInt();
                 chunkTimestamps[i] = lastModValue;
             }
         } catch (IOException e) {
             e.printStackTrace();
         }
     }

     /* the modification date of the region file when it was first opened */
     public long lastModified() {
         return lastModified;
     }

     /* gets how much the region file has grown since it was last checked */
     public synchronized int getSizeDelta() {
         int ret = sizeDelta;
         sizeDelta = 0;
         return ret;
     }

     // various small debug printing helpers
     private void debug(String in) {
 //        System.out.print(in);
     }

     private void debugln(String in) {
         debug(in + "\n");
     }

     private void debug(String mode, int x, int z, String in) {
         debug("REGION " + mode + " " + fileName.getName() + "[" + x + "," + z + "] = " + in);
     }

     /*
     private void debug(String mode, int x, int z, int count, String in) {
         debug("REGION " + mode + " " + fileName.getName() + "[" + x + "," + z + "] " + count + "B = " + in);
     }
     */

     private void debugln(String mode, int x, int z, String in) {
         debug(mode, x, z, in + "\n");
     }

     /*
      * gets an (uncompressed) stream representing the chunk data returns null if
      * the chunk is not found or an error occurs
      */
     public synchronized DataInputStream getChunkDataInputStream(int x, int z) {
         if (outOfBounds(x, z)) {
             debugln("READ", x, z, "out of bounds");
             return null;
         }

         try {
             int offset = getOffset(x, z);
             if (offset == 0) {
                 // debugln("READ", x, z, "miss");
                 return null;
             }

             int sectorNumber = offset >> 8;
             int numSectors = offset & 0xFF;

             if (sectorNumber + numSectors > sectorFree.size()) {
                 debugln("READ", x, z, "invalid sector");
                 return null;
             }

             file.seek(sectorNumber * SECTOR_BYTES);
             int length = file.readInt();

             if (length > SECTOR_BYTES * numSectors) {
                 debugln("READ", x, z, "invalid length: " + length + " > 4096 * " + numSectors);
                 return null;
             }

             byte version = file.readByte();
             if (version == VERSION_GZIP) {
                 byte[] data = new byte[length - 1];
                 file.read(data);
                 DataInputStream ret = new DataInputStream(new GZIPInputStream(new ByteArrayInputStream(data)));
                 // debug("READ", x, z, " = found");
                 return ret;
             } else if (version == VERSION_DEFLATE) {
                 byte[] data = new byte[length - 1];
                 file.read(data);
                 DataInputStream ret = new DataInputStream(new InflaterInputStream(new ByteArrayInputStream(data)));
                 // debug("READ", x, z, " = found");
                 return ret;
             }

             debugln("READ", x, z, "unknown version " + version);
             return null;
         } catch (IOException e) {
             debugln("READ", x, z, "exception");
             return null;
         }
     }

     /* Commented for X-Ray because we shouldn't be writing anything
     public DataOutputStream getChunkDataOutputStream(int x, int z) {
         if (outOfBounds(x, z)) return null;

         return new DataOutputStream(new DeflaterOutputStream(new ChunkBuffer(x, z)));
     }
     */

     /*
      * lets chunk writing be multithreaded by not locking the whole file as a
      * chunk is serializing -- only writes when serialization is over
      */
     /* Commented for X-Ray since we don't have any business writing things
     class ChunkBuffer extends ByteArrayOutputStream {
         private int x, z;

         public ChunkBuffer(int x, int z) {
             super(8096); // initialize to 8KB
             this.x = x;
             this.z = z;
         }

         public void close() {
             RegionFile.this.write(x, z, buf, count);
         }
     }
     */

     /* write a chunk at (x,z) with length bytes of data to disk */
     /* Commented for X-Ray because we don't have any business writing things out
     protected synchronized void write(int x, int z, byte[] data, int length) {
         try {
             int offset = getOffset(x, z);
             int sectorNumber = offset >> 8;
             int sectorsAllocated = offset & 0xFF;
             int sectorsNeeded = (length + CHUNK_HEADER_SIZE) / SECTOR_BYTES + 1;

             // maximum chunk size is 1MB
             if (sectorsNeeded >= 256) {
                 return;
             }

             if (sectorNumber != 0 && sectorsAllocated == sectorsNeeded) {
                 // we can simply overwrite the old sectors
                 debug("SAVE", x, z, length, "rewrite");
                 write(sectorNumber, data, length);
             } else {
                 // we need to allocate new sectors

                 // mark the sectors previously used for this chunk as free
                 for (int i = 0; i < sectorsAllocated; ++i) {
                     sectorFree.set(sectorNumber + i, true);
                 }

                 // scan for a free space large enough to store this chunk
                 int runStart = sectorFree.indexOf(true);
                 int runLength = 0;
                 if (runStart != -1) {
                     for (int i = runStart; i < sectorFree.size(); ++i) {
                         if (runLength != 0) {
                             if (sectorFree.get(i)) runLength++;
                             else runLength = 0;
                         } else if (sectorFree.get(i)) {
                             runStart = i;
                             runLength = 1;
                         }
                         if (runLength >= sectorsNeeded) {
                             break;
                         }
                     }
                 }

                 if (runLength >= sectorsNeeded) {
                     // we found a free space large enough
                     debug("SAVE", x, z, length, "reuse");
                     sectorNumber = runStart;
                     setOffset(x, z, (sectorNumber << 8) | sectorsNeeded);
                     for (int i = 0; i < sectorsNeeded; ++i) {
                         sectorFree.set(sectorNumber + i, false);
                     }
                     write(sectorNumber, data, length);
                 } else {
                      // no free space large enough found -- we need to grow the file
                     debug("SAVE", x, z, length, "grow");
                     file.seek(file.length());
                     sectorNumber = sectorFree.size();
                     for (int i = 0; i < sectorsNeeded; ++i) {
                         file.write(emptySector);
                         sectorFree.add(false);
                     }
                     sizeDelta += SECTOR_BYTES * sectorsNeeded;

                     write(sectorNumber, data, length);
                     setOffset(x, z, (sectorNumber << 8) | sectorsNeeded);
                 }
             }
             setTimestamp(x, z, (int) (System.currentTimeMillis() / 1000L));
         } catch (IOException e) {
             e.printStackTrace();
         }
     }
     */

     /* write a chunk data to the region file at specified sector number */
     /* Commented for X-Ray because we don't have any business writing things
     private void write(int sectorNumber, byte[] data, int length) throws IOException {
         debugln(" " + sectorNumber);
         file.seek(sectorNumber * SECTOR_BYTES);
         file.writeInt(length + 1); // chunk length
         file.writeByte(VERSION_DEFLATE); // chunk version number
         file.write(data, 0, length); // chunk data
     }
     */

     /* is this an invalid chunk coordinate? */
     private boolean outOfBounds(int x, int z) {
         return x < 0 || x >= 32 || z < 0 || z >= 32;
     }

     private int getOffset(int x, int z) {
         return offsets[x + z * 32];
     }

     public boolean hasChunk(int x, int z) {
         return getOffset(x, z) != 0;
     }

     /* Commented for X-Ray
     private void setOffset(int x, int z, int offset) throws IOException {
         offsets[x + z * 32] = offset;
         file.seek((x + z * 32) * 4);
         file.writeInt(offset);
     }
     */

     /* Commented for X-Ray
     private void setTimestamp(int x, int z, int value) throws IOException {
         chunkTimestamps[x + z * 32] = value;
         file.seek(SECTOR_BYTES + (x + z * 32) * 4);
         file.writeInt(value);
     }
     */

     public void close() throws IOException {
         file.close();
     }
 }
	/*
	** 2011 January 5
	**
	** The author disclaims copyright to this source code. In place of
	** a legal notice, here is a blessing:
	**
	** May you do good and not evil.
	** May you find forgiveness for yourself and forgive others.
	** May you share freely, never taking more than you give.
	**/

	/*
	* 2011 February 16
	*
	* This source code is based on the work of Scaevolus (see notice above).
	* It has been slightly modified by Mojang AB (constants instead of magic
	* numbers, a chunk timestamp header, and auto-formatted according to our
	* formatter template).
	*
	*/

	/*
	* 2011 February 20
	*
	* Imported by CJ Kucera into X-Ray, from a blog post by Jens Bergensten
	* at: http://mojang.com/2011/02/16/minecraft-save-file-format-in-beta-1-3/
	*/

	// Interfaces with region files on the disk

	/*

	Region File Format

	Concept: The minimum unit of storage on hard drives is 4KB. 90% of Minecraft
	chunks are smaller than 4KB. 99% are smaller than 8KB. Write a simple
	container to store chunks in single files in runs of 4KB sectors.

	Each region file represents a 32x32 group of chunks. The conversion from
	chunk number to region number is floor(coord / 32): a chunk at (30, -3)
	would be in region (0, -1), and one at (70, -30) would be at (3, -1).
	Region files are named "r.x.z.data", where x and z are the region coordinates.

	A region file begins with a 4KB header that describes where chunks are stored
	in the file. A 4-byte big-endian integer represents sector offsets and sector
	counts. The chunk offset for a chunk (x, z) begins at byte 4(x+z32) in the
	file. The bottom byte of the chunk offset indicates the number of sectors the
	chunk takes up, and the top 3 bytes represent the sector number of the chunk.
	Given a chunk offset o, the chunk data begins at byte 4096*(o/256) and takes up
	at most 4096*(o%256) bytes. A chunk cannot exceed 1MB in size. If a chunk
	offset is 0, the corresponding chunk is not stored in the region file.

	Chunk data begins with a 4-byte big-endian integer representing the chunk data
	length in bytes, not counting the length field. The length must be smaller than
	4096 times the number of sectors. The next byte is a version field, to allow
	backwards-compatible updates to how chunks are encoded.

	A version of 1 represents a gzipped NBT file. The gzipped data is the chunk
	length - 1.

	A version of 2 represents a deflated (zlib compressed) NBT file. The deflated
	data is the chunk length - 1.

	*/
	package com.apocalyptech.minecraft.xray;

	import java.io.*;
	import java.util.ArrayList;
	import java.util.zip.*;

	public class RegionFile {

	private static final int VERSION_GZIP = 1;
	private static final int VERSION_DEFLATE = 2;

	private static final int SECTOR_BYTES = 4096;
	private static final int SECTOR_INTS = SECTOR_BYTES / 4;

	static final int CHUNK_HEADER_SIZE = 5;
	//private static final byte emptySector[] = new byte[4096];

	private final File fileName;
	private RandomAccessFile file;
	private final int offsets[];
	private final int chunkTimestamps[];
	private ArrayList<Boolean> sectorFree;
	private int sizeDelta;
	private long lastModified = 0;

	public RegionFile(File path) {
	offsets = new int[SECTOR_INTS];
	chunkTimestamps = new int[SECTOR_INTS];

	fileName = path;
	debugln("REGION LOAD " + fileName);

	sizeDelta = 0;

	try {
	if (path.exists()) {
	lastModified = path.lastModified();
	}

	file = new RandomAccessFile(path, "r");

	if (file.length() < SECTOR_BYTES) {
	/* we need to write the chunk offset table */
	for (int i = 0; i < SECTOR_INTS; ++i) {
	file.writeInt(0);
	}
	// write another sector for the timestamp info
	for (int i = 0; i < SECTOR_INTS; ++i) {
	file.writeInt(0);
	}

	sizeDelta += SECTOR_BYTES * 2;
	}

	if ((file.length() & 0xfff) != 0) {
	/* the file size is not a multiple of 4KB, grow it */
	for (int i = 0; i < (file.length() & 0xfff); ++i) {
	file.write((byte) 0);
	}
	}

	/* set up the available sector map */
	int nSectors = (int) file.length() / SECTOR_BYTES;
	sectorFree = new ArrayList<Boolean>(nSectors);

	for (int i = 0; i < nSectors; ++i) {
	sectorFree.add(true);
	}

	sectorFree.set(0, false); // chunk offset table
	sectorFree.set(1, false); // for the last modified info

	file.seek(0);
	for (int i = 0; i < SECTOR_INTS; ++i) {
	int offset = file.readInt();
	offsets[i] = offset;
	if (offset != 0 && (offset >> 8) + (offset & 0xFF) <= sectorFree.size()) {
	for (int sectorNum = 0; sectorNum < (offset & 0xFF); ++sectorNum) {
	sectorFree.set((offset >> 8) + sectorNum, false);
	}
	}
	}
	for (int i = 0; i < SECTOR_INTS; ++i) {
	int lastModValue = file.readInt();
	chunkTimestamps[i] = lastModValue;
	}
	} catch (IOException e) {
	e.printStackTrace();
	}
	}

	/* the modification date of the region file when it was first opened */
	public long lastModified() {
	return lastModified;
	}

	/* gets how much the region file has grown since it was last checked */
	public synchronized int getSizeDelta() {
	int ret = sizeDelta;
	sizeDelta = 0;
	return ret;
	}

	// various small debug printing helpers
	private void debug(String in) {
	// System.out.print(in);
	}

	private void debugln(String in) {
	debug(in + "\n");
	}

	private void debug(String mode, int x, int z, String in) {
	debug("REGION " + mode + " " + fileName.getName() + "[" + x + "," + z + "] = " + in);
	}

	/*
	private void debug(String mode, int x, int z, int count, String in) {
	debug("REGION " + mode + " " + fileName.getName() + "[" + x + "," + z + "] " + count + "B = " + in);
	}
	*/

	private void debugln(String mode, int x, int z, String in) {
	debug(mode, x, z, in + "\n");
	}

	/*
	* gets an (uncompressed) stream representing the chunk data returns null if
	* the chunk is not found or an error occurs
	*/
	public synchronized DataInputStream getChunkDataInputStream(int x, int z) {
	if (outOfBounds(x, z)) {
	debugln("READ", x, z, "out of bounds");
	return null;
	}

	try {
	int offset = getOffset(x, z);
	if (offset == 0) {
	// debugln("READ", x, z, "miss");
	return null;
	}

	int sectorNumber = offset >> 8;
	int numSectors = offset & 0xFF;

	if (sectorNumber + numSectors > sectorFree.size()) {
	debugln("READ", x, z, "invalid sector");
	return null;
	}

	file.seek(sectorNumber * SECTOR_BYTES);
	int length = file.readInt();

	if (length > SECTOR_BYTES * numSectors) {
	debugln("READ", x, z, "invalid length: " + length + " > 4096 * " + numSectors);
	return null;
	}

	byte version = file.readByte();
	if (version == VERSION_GZIP) {
	byte[] data = new byte[length - 1];
	file.read(data);
	DataInputStream ret = new DataInputStream(new GZIPInputStream(new ByteArrayInputStream(data)));
	// debug("READ", x, z, " = found");
	return ret;
	} else if (version == VERSION_DEFLATE) {
	byte[] data = new byte[length - 1];
	file.read(data);
	DataInputStream ret = new DataInputStream(new InflaterInputStream(new ByteArrayInputStream(data)));
	// debug("READ", x, z, " = found");
	return ret;
	}

	debugln("READ", x, z, "unknown version " + version);
	return null;
	} catch (IOException e) {
	debugln("READ", x, z, "exception");
	return null;
	}
	}

	/* Commented for X-Ray because we shouldn't be writing anything
	public DataOutputStream getChunkDataOutputStream(int x, int z) {
	if (outOfBounds(x, z)) return null;

	return new DataOutputStream(new DeflaterOutputStream(new ChunkBuffer(x, z)));
	}
	*/

	/*
	* lets chunk writing be multithreaded by not locking the whole file as a
	* chunk is serializing -- only writes when serialization is over
	*/
	/* Commented for X-Ray since we don't have any business writing things
	class ChunkBuffer extends ByteArrayOutputStream {
	private int x, z;

	public ChunkBuffer(int x, int z) {
	super(8096); // initialize to 8KB
	this.x = x;
	this.z = z;
	}

	public void close() {
	RegionFile.this.write(x, z, buf, count);
	}
	}
	*/

	/* write a chunk at (x,z) with length bytes of data to disk */
	/* Commented for X-Ray because we don't have any business writing things out
	protected synchronized void write(int x, int z, byte[] data, int length) {
	try {
	int offset = getOffset(x, z);
	int sectorNumber = offset >> 8;
	int sectorsAllocated = offset & 0xFF;
	int sectorsNeeded = (length + CHUNK_HEADER_SIZE) / SECTOR_BYTES + 1;

	// maximum chunk size is 1MB
	if (sectorsNeeded >= 256) {
	return;
	}

	if (sectorNumber != 0 && sectorsAllocated == sectorsNeeded) {
	// we can simply overwrite the old sectors
	debug("SAVE", x, z, length, "rewrite");
	write(sectorNumber, data, length);
	} else {
	// we need to allocate new sectors

	// mark the sectors previously used for this chunk as free
	for (int i = 0; i < sectorsAllocated; ++i) {
	sectorFree.set(sectorNumber + i, true);
	}

	// scan for a free space large enough to store this chunk
	int runStart = sectorFree.indexOf(true);
	int runLength = 0;
	if (runStart != -1) {
	for (int i = runStart; i < sectorFree.size(); ++i) {
	if (runLength != 0) {
	if (sectorFree.get(i)) runLength++;
	else runLength = 0;
	} else if (sectorFree.get(i)) {
	runStart = i;
	runLength = 1;
	}
	if (runLength >= sectorsNeeded) {
	break;
	}
	}
	}

	if (runLength >= sectorsNeeded) {
	// we found a free space large enough
	debug("SAVE", x, z, length, "reuse");
	sectorNumber = runStart;
	setOffset(x, z, (sectorNumber << 8) \| sectorsNeeded);
	for (int i = 0; i < sectorsNeeded; ++i) {
	sectorFree.set(sectorNumber + i, false);
	}
	write(sectorNumber, data, length);
	} else {
	// no free space large enough found -- we need to grow the file
	debug("SAVE", x, z, length, "grow");
	file.seek(file.length());
	sectorNumber = sectorFree.size();
	for (int i = 0; i < sectorsNeeded; ++i) {
	file.write(emptySector);
	sectorFree.add(false);
	}
	sizeDelta += SECTOR_BYTES * sectorsNeeded;

	write(sectorNumber, data, length);
	setOffset(x, z, (sectorNumber << 8) \| sectorsNeeded);
	}
	}
	setTimestamp(x, z, (int) (System.currentTimeMillis() / 1000L));
	} catch (IOException e) {
	e.printStackTrace();
	}
	}
	*/

	/* write a chunk data to the region file at specified sector number */
	/* Commented for X-Ray because we don't have any business writing things
	private void write(int sectorNumber, byte[] data, int length) throws IOException {
	debugln(" " + sectorNumber);
	file.seek(sectorNumber * SECTOR_BYTES);
	file.writeInt(length + 1); // chunk length
	file.writeByte(VERSION_DEFLATE); // chunk version number
	file.write(data, 0, length); // chunk data
	}
	*/

	/* is this an invalid chunk coordinate? */
	private boolean outOfBounds(int x, int z) {
	return x < 0 \|\| x >= 32 \|\| z < 0 \|\| z >= 32;
	}

	private int getOffset(int x, int z) {
	return offsets[x + z * 32];
	}

	public boolean hasChunk(int x, int z) {
	return getOffset(x, z) != 0;
	}

	/* Commented for X-Ray
	private void setOffset(int x, int z, int offset) throws IOException {
	offsets[x + z * 32] = offset;
	file.seek((x + z * 32) * 4);
	file.writeInt(offset);
	}
	*/

	/* Commented for X-Ray
	private void setTimestamp(int x, int z, int value) throws IOException {
	chunkTimestamps[x + z * 32] = value;
	file.seek(SECTOR_BYTES + (x + z * 32) * 4);
	file.writeInt(value);
	}
	*/

	public void close() throws IOException {
	file.close();
	}
	}