| /* |
| * Copyright (C) 2015, Matthias Sohn <matthias.sohn@sap.com> 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.lfs.lib; |
| |
| import java.io.Serializable; |
| import java.text.MessageFormat; |
| |
| import org.eclipse.jgit.lfs.errors.InvalidLongObjectIdException; |
| import org.eclipse.jgit.lfs.internal.LfsText; |
| import org.eclipse.jgit.util.NB; |
| import org.eclipse.jgit.util.RawParseUtils; |
| |
| /** |
| * A prefix abbreviation of an {@link org.eclipse.jgit.lfs.lib.LongObjectId}. |
| * <p> |
| * Enable abbreviating SHA-256 strings used by Git LFS, using sufficient leading |
| * digits from the LongObjectId name to still be unique within the repository |
| * the string was generated from. These ids are likely to be unique for a useful |
| * period of time, especially if they contain at least 6-10 hex digits. |
| * <p> |
| * This class converts the hex string into a binary form, to make it more |
| * efficient for matching against an object. |
| * |
| * Ported to SHA-256 from {@link org.eclipse.jgit.lib.AbbreviatedObjectId} |
| * |
| * @since 4.3 |
| */ |
| public final class AbbreviatedLongObjectId implements Serializable { |
| private static final long serialVersionUID = 1L; |
| |
| /** |
| * Test a string of characters to verify it is a hex format. |
| * <p> |
| * If true the string can be parsed with {@link #fromString(String)}. |
| * |
| * @param id |
| * the string to test. |
| * @return true if the string can converted into an AbbreviatedObjectId. |
| */ |
| public static final boolean isId(String id) { |
| if (id.length() < 2 |
| || Constants.LONG_OBJECT_ID_STRING_LENGTH < id.length()) |
| return false; |
| try { |
| for (int i = 0; i < id.length(); i++) |
| RawParseUtils.parseHexInt4((byte) id.charAt(i)); |
| return true; |
| } catch (ArrayIndexOutOfBoundsException e) { |
| return false; |
| } |
| } |
| |
| /** |
| * Convert an AbbreviatedObjectId from hex characters (US-ASCII). |
| * |
| * @param buf |
| * the US-ASCII buffer to read from. |
| * @param offset |
| * position to read the first character from. |
| * @param end |
| * one past the last position to read (<code>end-offset</code> is |
| * the length of the string). |
| * @return the converted object id. |
| */ |
| public static final AbbreviatedLongObjectId fromString(final byte[] buf, |
| final int offset, final int end) { |
| if (end - offset > Constants.LONG_OBJECT_ID_STRING_LENGTH) |
| throw new IllegalArgumentException(MessageFormat.format( |
| LfsText.get().invalidLongIdLength, |
| Integer.valueOf(end - offset), |
| Integer.valueOf(Constants.LONG_OBJECT_ID_STRING_LENGTH))); |
| return fromHexString(buf, offset, end); |
| } |
| |
| /** |
| * Convert an AbbreviatedObjectId from an |
| * {@link org.eclipse.jgit.lib.AnyObjectId}. |
| * <p> |
| * This method copies over all bits of the Id, and is therefore complete |
| * (see {@link #isComplete()}). |
| * |
| * @param id |
| * the {@link org.eclipse.jgit.lib.ObjectId} to convert from. |
| * @return the converted object id. |
| */ |
| public static final AbbreviatedLongObjectId fromLongObjectId( |
| AnyLongObjectId id) { |
| return new AbbreviatedLongObjectId( |
| Constants.LONG_OBJECT_ID_STRING_LENGTH, id.w1, id.w2, id.w3, |
| id.w4); |
| } |
| |
| /** |
| * Convert an AbbreviatedLongObjectId from hex characters. |
| * |
| * @param str |
| * the string to read from. Must be <= 64 characters. |
| * @return the converted object id. |
| */ |
| public static final AbbreviatedLongObjectId fromString(String str) { |
| if (str.length() > Constants.LONG_OBJECT_ID_STRING_LENGTH) |
| throw new IllegalArgumentException( |
| MessageFormat.format(LfsText.get().invalidLongId, str)); |
| final byte[] b = org.eclipse.jgit.lib.Constants.encodeASCII(str); |
| return fromHexString(b, 0, b.length); |
| } |
| |
| private static final AbbreviatedLongObjectId fromHexString(final byte[] bs, |
| int ptr, final int end) { |
| try { |
| final long a = hexUInt64(bs, ptr, end); |
| final long b = hexUInt64(bs, ptr + 16, end); |
| final long c = hexUInt64(bs, ptr + 32, end); |
| final long d = hexUInt64(bs, ptr + 48, end); |
| return new AbbreviatedLongObjectId(end - ptr, a, b, c, d); |
| } catch (ArrayIndexOutOfBoundsException e) { |
| InvalidLongObjectIdException e1 = new InvalidLongObjectIdException( |
| bs, ptr, end - ptr); |
| e1.initCause(e); |
| throw e1; |
| } |
| } |
| |
| private static final long hexUInt64(final byte[] bs, int p, final int end) { |
| if (16 <= end - p) |
| return RawParseUtils.parseHexInt64(bs, p); |
| |
| long r = 0; |
| int n = 0; |
| while (n < 16 && p < end) { |
| r <<= 4; |
| r |= RawParseUtils.parseHexInt4(bs[p++]); |
| n++; |
| } |
| return r << ((16 - n) * 4); |
| } |
| |
| static long mask(int nibbles, long word, long v) { |
| final long b = (word - 1) * 16; |
| if (b + 16 <= nibbles) { |
| // We have all of the bits required for this word. |
| // |
| return v; |
| } |
| |
| if (nibbles <= b) { |
| // We have none of the bits required for this word. |
| // |
| return 0; |
| } |
| |
| final long s = 64 - (nibbles - b) * 4; |
| return (v >>> s) << s; |
| } |
| |
| /** Number of half-bytes used by this id. */ |
| final int nibbles; |
| |
| final long w1; |
| |
| final long w2; |
| |
| final long w3; |
| |
| final long w4; |
| |
| AbbreviatedLongObjectId(final int n, final long new_1, final long new_2, |
| final long new_3, final long new_4) { |
| nibbles = n; |
| w1 = new_1; |
| w2 = new_2; |
| w3 = new_3; |
| w4 = new_4; |
| } |
| |
| /** |
| * Get length |
| * |
| * @return number of hex digits appearing in this id. |
| */ |
| public int length() { |
| return nibbles; |
| } |
| |
| /** |
| * Check if this id is complete |
| * |
| * @return true if this ObjectId is actually a complete id. |
| */ |
| public boolean isComplete() { |
| return length() == Constants.LONG_OBJECT_ID_STRING_LENGTH; |
| } |
| |
| /** |
| * Convert to LongObjectId |
| * |
| * @return a complete ObjectId; null if {@link #isComplete()} is false. |
| */ |
| public LongObjectId toLongObjectId() { |
| return isComplete() ? new LongObjectId(w1, w2, w3, w4) : null; |
| } |
| |
| /** |
| * Compares this abbreviation to a full object id. |
| * |
| * @param other |
| * the other object id. |
| * @return <0 if this abbreviation names an object that is less than |
| * <code>other</code>; 0 if this abbreviation exactly matches the |
| * first {@link #length()} digits of <code>other.name()</code>; |
| * >0 if this abbreviation names an object that is after |
| * <code>other</code>. |
| */ |
| public final int prefixCompare(AnyLongObjectId other) { |
| int cmp; |
| |
| cmp = NB.compareUInt64(w1, mask(1, other.w1)); |
| if (cmp != 0) |
| return cmp; |
| |
| cmp = NB.compareUInt64(w2, mask(2, other.w2)); |
| if (cmp != 0) |
| return cmp; |
| |
| cmp = NB.compareUInt64(w3, mask(3, other.w3)); |
| if (cmp != 0) |
| return cmp; |
| |
| return NB.compareUInt64(w4, mask(4, other.w4)); |
| } |
| |
| /** |
| * Compare this abbreviation to a network-byte-order LongObjectId. |
| * |
| * @param bs |
| * array containing the other LongObjectId in network byte order. |
| * @param p |
| * position within {@code bs} to start the compare at. At least |
| * 32 bytes, starting at this position are required. |
| * @return <0 if this abbreviation names an object that is less than |
| * <code>other</code>; 0 if this abbreviation exactly matches the |
| * first {@link #length()} digits of <code>other.name()</code>; |
| * >0 if this abbreviation names an object that is after |
| * <code>other</code>. |
| */ |
| public final int prefixCompare(byte[] bs, int p) { |
| int cmp; |
| |
| cmp = NB.compareUInt64(w1, mask(1, NB.decodeInt64(bs, p))); |
| if (cmp != 0) |
| return cmp; |
| |
| cmp = NB.compareUInt64(w2, mask(2, NB.decodeInt64(bs, p + 8))); |
| if (cmp != 0) |
| return cmp; |
| |
| cmp = NB.compareUInt64(w3, mask(3, NB.decodeInt64(bs, p + 16))); |
| if (cmp != 0) |
| return cmp; |
| |
| return NB.compareUInt64(w4, mask(4, NB.decodeInt64(bs, p + 24))); |
| } |
| |
| /** |
| * Compare this abbreviation to a network-byte-order LongObjectId. |
| * |
| * @param bs |
| * array containing the other LongObjectId in network byte order. |
| * @param p |
| * position within {@code bs} to start the compare at. At least 4 |
| * longs, starting at this position are required. |
| * @return <0 if this abbreviation names an object that is less than |
| * <code>other</code>; 0 if this abbreviation exactly matches the |
| * first {@link #length()} digits of <code>other.name()</code>; |
| * >0 if this abbreviation names an object that is after |
| * <code>other</code>. |
| */ |
| public final int prefixCompare(long[] bs, int p) { |
| int cmp; |
| |
| cmp = NB.compareUInt64(w1, mask(1, bs[p])); |
| if (cmp != 0) |
| return cmp; |
| |
| cmp = NB.compareUInt64(w2, mask(2, bs[p + 1])); |
| if (cmp != 0) |
| return cmp; |
| |
| cmp = NB.compareUInt64(w3, mask(3, bs[p + 2])); |
| if (cmp != 0) |
| return cmp; |
| |
| return NB.compareUInt64(w4, mask(4, bs[p + 3])); |
| } |
| |
| /** |
| * Get the first byte of this id |
| * |
| * @return value for a fan-out style map, only valid of length >= 2. |
| */ |
| public final int getFirstByte() { |
| return (int) (w1 >>> 56); |
| } |
| |
| private long mask(long word, long v) { |
| return mask(nibbles, word, v); |
| } |
| |
| /** {@inheritDoc} */ |
| @Override |
| public int hashCode() { |
| return (int) (w1 >> 32); |
| } |
| |
| /** {@inheritDoc} */ |
| @Override |
| public boolean equals(Object o) { |
| if (o instanceof AbbreviatedLongObjectId) { |
| final AbbreviatedLongObjectId b = (AbbreviatedLongObjectId) o; |
| return nibbles == b.nibbles && w1 == b.w1 && w2 == b.w2 |
| && w3 == b.w3 && w4 == b.w4; |
| } |
| return false; |
| } |
| |
| /** |
| * <p>name.</p> |
| * |
| * @return string form of the abbreviation, in lower case hexadecimal. |
| */ |
| public final String name() { |
| final char[] b = new char[Constants.LONG_OBJECT_ID_STRING_LENGTH]; |
| |
| AnyLongObjectId.formatHexChar(b, 0, w1); |
| if (nibbles <= 16) |
| return new String(b, 0, nibbles); |
| |
| AnyLongObjectId.formatHexChar(b, 16, w2); |
| if (nibbles <= 32) |
| return new String(b, 0, nibbles); |
| |
| AnyLongObjectId.formatHexChar(b, 32, w3); |
| if (nibbles <= 48) |
| return new String(b, 0, nibbles); |
| |
| AnyLongObjectId.formatHexChar(b, 48, w4); |
| return new String(b, 0, nibbles); |
| } |
| |
| /** {@inheritDoc} */ |
| @SuppressWarnings("nls") |
| @Override |
| public String toString() { |
| return "AbbreviatedLongObjectId[" + name() + "]"; //$NON-NLS-1$ |
| } |
| } |