| /* |
| * Copyright (C) 2007, Robin Rosenberg <robin.rosenberg@dewire.com> |
| * Copyright (C) 2006-2007, Shawn O. Pearce <spearce@spearce.org> and others |
| * |
| * This program and the accompanying materials are made available under the |
| * terms of the Eclipse Distribution License v. 1.0 which is available at |
| * https://www.eclipse.org/org/documents/edl-v10.php. |
| * |
| * SPDX-License-Identifier: BSD-3-Clause |
| */ |
| |
| package org.eclipse.jgit.internal.storage.pack; |
| |
| import org.eclipse.jgit.internal.JGitText; |
| import org.eclipse.jgit.util.QuotedString; |
| import org.eclipse.jgit.util.RawParseUtils; |
| |
| /** |
| * Recreate a stream from a base stream and a GIT pack delta. |
| * <p> |
| * This entire class is heavily cribbed from <code>patch-delta.c</code> in the |
| * GIT project. The original delta patching code was written by Nicolas Pitre |
| * (<nico@cam.org>). |
| * </p> |
| */ |
| public class BinaryDelta { |
| /** |
| * Length of the base object in the delta stream. |
| * |
| * @param delta |
| * the delta stream, or at least the header of it. |
| * @return the base object's size. |
| */ |
| public static long getBaseSize(byte[] delta) { |
| int p = 0; |
| long baseLen = 0; |
| int c, shift = 0; |
| do { |
| c = delta[p++] & 0xff; |
| baseLen |= ((long) (c & 0x7f)) << shift; |
| shift += 7; |
| } while ((c & 0x80) != 0); |
| return baseLen; |
| } |
| |
| /** |
| * Length of the resulting object in the delta stream. |
| * |
| * @param delta |
| * the delta stream, or at least the header of it. |
| * @return the resulting object's size. |
| */ |
| public static long getResultSize(byte[] delta) { |
| int p = 0; |
| |
| // Skip length of the base object. |
| // |
| int c; |
| do { |
| c = delta[p++] & 0xff; |
| } while ((c & 0x80) != 0); |
| |
| long resLen = 0; |
| int shift = 0; |
| do { |
| c = delta[p++] & 0xff; |
| resLen |= ((long) (c & 0x7f)) << shift; |
| shift += 7; |
| } while ((c & 0x80) != 0); |
| return resLen; |
| } |
| |
| /** |
| * Apply the changes defined by delta to the data in base, yielding a new |
| * array of bytes. |
| * |
| * @param base |
| * some byte representing an object of some kind. |
| * @param delta |
| * a git pack delta defining the transform from one version to |
| * another. |
| * @return patched base |
| */ |
| public static final byte[] apply(byte[] base, byte[] delta) { |
| return apply(base, delta, null); |
| } |
| |
| /** |
| * Apply the changes defined by delta to the data in base, yielding a new |
| * array of bytes. |
| * |
| * @param base |
| * some byte representing an object of some kind. |
| * @param delta |
| * a git pack delta defining the transform from one version to |
| * another. |
| * @param result |
| * array to store the result into. If null the result will be |
| * allocated and returned. |
| * @return either {@code result}, or the result array allocated. |
| */ |
| public static final byte[] apply(final byte[] base, final byte[] delta, |
| byte[] result) { |
| int deltaPtr = 0; |
| |
| // Length of the base object (a variable length int). |
| // |
| int baseLen = 0; |
| int c, shift = 0; |
| do { |
| c = delta[deltaPtr++] & 0xff; |
| baseLen |= (c & 0x7f) << shift; |
| shift += 7; |
| } while ((c & 0x80) != 0); |
| if (base.length != baseLen) |
| throw new IllegalArgumentException( |
| JGitText.get().baseLengthIncorrect); |
| |
| // Length of the resulting object (a variable length int). |
| // |
| int resLen = 0; |
| shift = 0; |
| do { |
| c = delta[deltaPtr++] & 0xff; |
| resLen |= (c & 0x7f) << shift; |
| shift += 7; |
| } while ((c & 0x80) != 0); |
| |
| if (result == null) |
| result = new byte[resLen]; |
| else if (result.length != resLen) |
| throw new IllegalArgumentException( |
| JGitText.get().resultLengthIncorrect); |
| |
| int resultPtr = 0; |
| while (deltaPtr < delta.length) { |
| final int cmd = delta[deltaPtr++] & 0xff; |
| if ((cmd & 0x80) != 0) { |
| // Determine the segment of the base which should |
| // be copied into the output. The segment is given |
| // as an offset and a length. |
| // |
| int copyOffset = 0; |
| if ((cmd & 0x01) != 0) |
| copyOffset = delta[deltaPtr++] & 0xff; |
| if ((cmd & 0x02) != 0) |
| copyOffset |= (delta[deltaPtr++] & 0xff) << 8; |
| if ((cmd & 0x04) != 0) |
| copyOffset |= (delta[deltaPtr++] & 0xff) << 16; |
| if ((cmd & 0x08) != 0) |
| copyOffset |= (delta[deltaPtr++] & 0xff) << 24; |
| |
| int copySize = 0; |
| if ((cmd & 0x10) != 0) |
| copySize = delta[deltaPtr++] & 0xff; |
| if ((cmd & 0x20) != 0) |
| copySize |= (delta[deltaPtr++] & 0xff) << 8; |
| if ((cmd & 0x40) != 0) |
| copySize |= (delta[deltaPtr++] & 0xff) << 16; |
| if (copySize == 0) |
| copySize = 0x10000; |
| |
| System.arraycopy(base, copyOffset, result, resultPtr, copySize); |
| resultPtr += copySize; |
| } else if (cmd != 0) { |
| // Anything else the data is literal within the delta |
| // itself. |
| // |
| System.arraycopy(delta, deltaPtr, result, resultPtr, cmd); |
| deltaPtr += cmd; |
| resultPtr += cmd; |
| } else { |
| // cmd == 0 has been reserved for future encoding but |
| // for now its not acceptable. |
| // |
| throw new IllegalArgumentException( |
| JGitText.get().unsupportedCommand0); |
| } |
| } |
| |
| return result; |
| } |
| |
| /** |
| * Format this delta as a human readable string. |
| * |
| * @param delta |
| * the delta instruction sequence to format. |
| * @return the formatted delta. |
| */ |
| public static String format(byte[] delta) { |
| return format(delta, true); |
| } |
| |
| /** |
| * Format this delta as a human readable string. |
| * |
| * @param delta |
| * the delta instruction sequence to format. |
| * @param includeHeader |
| * true if the header (base size and result size) should be |
| * included in the formatting. |
| * @return the formatted delta. |
| */ |
| public static String format(byte[] delta, boolean includeHeader) { |
| StringBuilder r = new StringBuilder(); |
| int deltaPtr = 0; |
| |
| long baseLen = 0; |
| int c, shift = 0; |
| do { |
| c = delta[deltaPtr++] & 0xff; |
| baseLen |= ((long) (c & 0x7f)) << shift; |
| shift += 7; |
| } while ((c & 0x80) != 0); |
| |
| long resLen = 0; |
| shift = 0; |
| do { |
| c = delta[deltaPtr++] & 0xff; |
| resLen |= ((long) (c & 0x7f)) << shift; |
| shift += 7; |
| } while ((c & 0x80) != 0); |
| |
| if (includeHeader) { |
| r.append("DELTA( BASE="); //$NON-NLS-1$ |
| r.append(baseLen); |
| r.append(" RESULT="); //$NON-NLS-1$ |
| r.append(resLen); |
| r.append(" )\n"); //$NON-NLS-1$ |
| } |
| |
| while (deltaPtr < delta.length) { |
| final int cmd = delta[deltaPtr++] & 0xff; |
| if ((cmd & 0x80) != 0) { |
| // Determine the segment of the base which should |
| // be copied into the output. The segment is given |
| // as an offset and a length. |
| // |
| int copyOffset = 0; |
| if ((cmd & 0x01) != 0) |
| copyOffset = delta[deltaPtr++] & 0xff; |
| if ((cmd & 0x02) != 0) |
| copyOffset |= (delta[deltaPtr++] & 0xff) << 8; |
| if ((cmd & 0x04) != 0) |
| copyOffset |= (delta[deltaPtr++] & 0xff) << 16; |
| if ((cmd & 0x08) != 0) |
| copyOffset |= (delta[deltaPtr++] & 0xff) << 24; |
| |
| int copySize = 0; |
| if ((cmd & 0x10) != 0) |
| copySize = delta[deltaPtr++] & 0xff; |
| if ((cmd & 0x20) != 0) |
| copySize |= (delta[deltaPtr++] & 0xff) << 8; |
| if ((cmd & 0x40) != 0) |
| copySize |= (delta[deltaPtr++] & 0xff) << 16; |
| if (copySize == 0) |
| copySize = 0x10000; |
| |
| r.append(" COPY ("); //$NON-NLS-1$ |
| r.append(copyOffset); |
| r.append(", "); //$NON-NLS-1$ |
| r.append(copySize); |
| r.append(")\n"); //$NON-NLS-1$ |
| } else if (cmd != 0) { |
| // Anything else the data is literal within the delta |
| // itself. |
| // |
| r.append(" INSERT("); //$NON-NLS-1$ |
| r.append(QuotedString.GIT_PATH.quote(RawParseUtils.decode( |
| delta, deltaPtr, deltaPtr + cmd))); |
| r.append(")\n"); //$NON-NLS-1$ |
| deltaPtr += cmd; |
| } else { |
| // cmd == 0 has been reserved for future encoding but |
| // for now its not acceptable. |
| // |
| throw new IllegalArgumentException( |
| JGitText.get().unsupportedCommand0); |
| } |
| } |
| |
| return r.toString(); |
| } |
| } |