Java tutorial
/* * Minecraft Forge * Copyright (c) 2016. * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation version 2.1 * of the License. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ package net.minecraftforge.fml.repackage.com.nothome.delta; import org.apache.commons.io.IOUtils; import static net.minecraftforge.fml.repackage.com.nothome.delta.GDiffWriter.COPY_INT_INT; import static net.minecraftforge.fml.repackage.com.nothome.delta.GDiffWriter.COPY_INT_UBYTE; import static net.minecraftforge.fml.repackage.com.nothome.delta.GDiffWriter.COPY_INT_USHORT; import static net.minecraftforge.fml.repackage.com.nothome.delta.GDiffWriter.COPY_LONG_INT; import static net.minecraftforge.fml.repackage.com.nothome.delta.GDiffWriter.COPY_USHORT_INT; import static net.minecraftforge.fml.repackage.com.nothome.delta.GDiffWriter.COPY_USHORT_UBYTE; import static net.minecraftforge.fml.repackage.com.nothome.delta.GDiffWriter.COPY_USHORT_USHORT; import static net.minecraftforge.fml.repackage.com.nothome.delta.GDiffWriter.DATA_INT; import static net.minecraftforge.fml.repackage.com.nothome.delta.GDiffWriter.DATA_MAX; import static net.minecraftforge.fml.repackage.com.nothome.delta.GDiffWriter.DATA_USHORT; import static net.minecraftforge.fml.repackage.com.nothome.delta.GDiffWriter.EOF; import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.EOFException; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.io.RandomAccessFile; import java.nio.ByteBuffer; /** * This class patches an input file with a GDIFF patch file. * * The patch file follows the GDIFF file specification available at * * <a href="http://www.w3.org/TR/NOTE-gdiff-19970901.html">http://www.w3.org/TR/NOTE-gdiff-19970901.html</a>. */ public class GDiffPatcher { private ByteBuffer buf = ByteBuffer.allocate(1024); private byte buf2[] = buf.array(); /** * Constructs a new GDiffPatcher. */ public GDiffPatcher() { } /** * Patches to an output file. */ public void patch(File sourceFile, File patchFile, File outputFile) throws IOException { RandomAccessFileSeekableSource source = new RandomAccessFileSeekableSource( new RandomAccessFile(sourceFile, "r")); InputStream patch = null; OutputStream output = null; try { patch = new FileInputStream(patchFile); output = new FileOutputStream(outputFile); patch(source, patch, output); } finally { IOUtils.closeQuietly(source); IOUtils.closeQuietly(patch); IOUtils.closeQuietly(output); } } /** * Patches to an output stream. */ public void patch(byte[] source, InputStream patch, OutputStream output) throws IOException { patch(new ByteBufferSeekableSource(source), patch, output); } /** * Patches in memory, returning the patch result. */ public byte[] patch(byte[] source, byte[] patch) throws IOException { ByteArrayOutputStream os = new ByteArrayOutputStream(); patch(source, new ByteArrayInputStream(patch), os); return os.toByteArray(); } /** * Patches to an output stream. */ public void patch(SeekableSource source, InputStream patch, OutputStream out) throws IOException { DataOutputStream outOS = new DataOutputStream(out); DataInputStream patchIS = new DataInputStream(patch); // the magic string is 'd1 ff d1 ff' + the version number if (patchIS.readUnsignedByte() != 0xd1 || patchIS.readUnsignedByte() != 0xff || patchIS.readUnsignedByte() != 0xd1 || patchIS.readUnsignedByte() != 0xff || patchIS.readUnsignedByte() != 0x04) { throw new PatchException("magic string not found, aborting!"); } while (true) { int command = patchIS.readUnsignedByte(); if (command == EOF) break; int length; int offset; if (command <= DATA_MAX) { append(command, patchIS, outOS); continue; } switch (command) { case DATA_USHORT: // ushort, n bytes following; append length = patchIS.readUnsignedShort(); append(length, patchIS, outOS); break; case DATA_INT: // int, n bytes following; append length = patchIS.readInt(); append(length, patchIS, outOS); break; case COPY_USHORT_UBYTE: offset = patchIS.readUnsignedShort(); length = patchIS.readUnsignedByte(); copy(offset, length, source, outOS); break; case COPY_USHORT_USHORT: offset = patchIS.readUnsignedShort(); length = patchIS.readUnsignedShort(); copy(offset, length, source, outOS); break; case COPY_USHORT_INT: offset = patchIS.readUnsignedShort(); length = patchIS.readInt(); copy(offset, length, source, outOS); break; case COPY_INT_UBYTE: offset = patchIS.readInt(); length = patchIS.readUnsignedByte(); copy(offset, length, source, outOS); break; case COPY_INT_USHORT: offset = patchIS.readInt(); length = patchIS.readUnsignedShort(); copy(offset, length, source, outOS); break; case COPY_INT_INT: offset = patchIS.readInt(); length = patchIS.readInt(); copy(offset, length, source, outOS); break; case COPY_LONG_INT: long loffset = patchIS.readLong(); length = patchIS.readInt(); copy(loffset, length, source, outOS); break; default: throw new IllegalStateException("command " + command); } } outOS.flush(); } private void copy(long offset, int length, SeekableSource source, OutputStream output) throws IOException { source.seek(offset); while (length > 0) { int len = Math.min(buf.capacity(), length); buf.clear().limit(len); int res = source.read(buf); if (res == -1) throw new EOFException("in copy " + offset + " " + length); output.write(buf.array(), 0, res); length -= res; } } private void append(int length, InputStream patch, OutputStream output) throws IOException { while (length > 0) { int len = Math.min(buf2.length, length); int res = patch.read(buf2, 0, len); if (res == -1) throw new EOFException("cannot read " + length); output.write(buf2, 0, res); length -= res; } } /** * Simple command line tool to patch a file. */ public static void main(String argv[]) { if (argv.length != 3) { System.err.println("usage GDiffPatch source patch output"); System.err.println("aborting.."); return; } try { File sourceFile = new File(argv[0]); File patchFile = new File(argv[1]); File outputFile = new File(argv[2]); if (sourceFile.length() > Integer.MAX_VALUE || patchFile.length() > Integer.MAX_VALUE) { System.err.println("source or patch is too large, max length is " + Integer.MAX_VALUE); System.err.println("aborting.."); return; } GDiffPatcher patcher = new GDiffPatcher(); patcher.patch(sourceFile, patchFile, outputFile); System.out.println("finished patching file"); } catch (Exception ioe) { //gls031504a System.err.println("error while patching: " + ioe); } } }