ObjectId.java

  1. /*
  2.  * Copyright (C) 2008, Robin Rosenberg <robin.rosenberg@dewire.com>
  3.  * Copyright (C) 2006-2008, Shawn O. Pearce <spearce@spearce.org> and others
  4.  *
  5.  * This program and the accompanying materials are made available under the
  6.  * terms of the Eclipse Distribution License v. 1.0 which is available at
  7.  * https://www.eclipse.org/org/documents/edl-v10.php.
  8.  *
  9.  * SPDX-License-Identifier: BSD-3-Clause
  10.  */

  12. package org.eclipse.jgit.lib;

  14. import java.io.IOException;
  15. import java.io.ObjectInputStream;
  16. import java.io.ObjectOutputStream;
  17. import java.io.Serializable;

  19. import org.eclipse.jgit.annotations.Nullable;
  20. import org.eclipse.jgit.errors.InvalidObjectIdException;
  21. import org.eclipse.jgit.util.NB;
  22. import org.eclipse.jgit.util.RawParseUtils;

  24. /**
  25.  * A SHA-1 abstraction.
  26.  */
  27. public class ObjectId extends AnyObjectId implements Serializable {
  28.     private static final long serialVersionUID = 1L;

  30.     private static final ObjectId ZEROID;

  32.     private static final String ZEROID_STR;

  34.     static {
  35.         ZEROID = new ObjectId(0, 0, 0, 0, 0);
  36.         ZEROID_STR = ZEROID.name();
  37.     }

  39.     /**
  40.      * Get the special all-null ObjectId.
  41.      *
  42.      * @return the all-null ObjectId, often used to stand-in for no object.
  43.      */
  44.     public static final ObjectId zeroId() {
  45.         return ZEROID;
  46.     }

  48.     /**
  49.      * Test a string of characters to verify it is a hex format.
  50.      * <p>
  51.      * If true the string can be parsed with {@link #fromString(String)}.
  52.      *
  53.      * @param id
  54.      *            the string to test.
  55.      * @return true if the string can converted into an ObjectId.
  56.      */
  57.     public static final boolean isId(@Nullable String id) {
  58.         if (id == null) {
  59.             return false;
  60.         }
  61.         if (id.length() != Constants.OBJECT_ID_STRING_LENGTH)
  62.             return false;
  63.         try {
  64.             for (int i = 0; i < Constants.OBJECT_ID_STRING_LENGTH; i++) {
  65.                 RawParseUtils.parseHexInt4((byte) id.charAt(i));
  66.             }
  67.             return true;
  68.         } catch (ArrayIndexOutOfBoundsException e) {
  69.             return false;
  70.         }
  71.     }

  73.     /**
  74.      * Convert an ObjectId into a hex string representation.
  75.      *
  76.      * @param i
  77.      *            the id to convert. May be null.
  78.      * @return the hex string conversion of this id's content.
  79.      */
  80.     public static final String toString(ObjectId i) {
  81.         return i != null ? i.name() : ZEROID_STR;
  82.     }

  84.     /**
  85.      * Compare two object identifier byte sequences for equality.
  86.      *
  87.      * @param firstBuffer
  88.      *            the first buffer to compare against. Must have at least 20
  89.      *            bytes from position fi through the end of the buffer.
  90.      * @param fi
  91.      *            first offset within firstBuffer to begin testing.
  92.      * @param secondBuffer
  93.      *            the second buffer to compare against. Must have at least 20
  94.      *            bytes from position si through the end of the buffer.
  95.      * @param si
  96.      *            first offset within secondBuffer to begin testing.
  97.      * @return true if the two identifiers are the same.
  98.      */
  99.     public static boolean equals(final byte[] firstBuffer, final int fi,
  100.             final byte[] secondBuffer, final int si) {
  101.         return firstBuffer[fi] == secondBuffer[si]
  102.                 && firstBuffer[fi + 1] == secondBuffer[si + 1]
  103.                 && firstBuffer[fi + 2] == secondBuffer[si + 2]
  104.                 && firstBuffer[fi + 3] == secondBuffer[si + 3]
  105.                 && firstBuffer[fi + 4] == secondBuffer[si + 4]
  106.                 && firstBuffer[fi + 5] == secondBuffer[si + 5]
  107.                 && firstBuffer[fi + 6] == secondBuffer[si + 6]
  108.                 && firstBuffer[fi + 7] == secondBuffer[si + 7]
  109.                 && firstBuffer[fi + 8] == secondBuffer[si + 8]
  110.                 && firstBuffer[fi + 9] == secondBuffer[si + 9]
  111.                 && firstBuffer[fi + 10] == secondBuffer[si + 10]
  112.                 && firstBuffer[fi + 11] == secondBuffer[si + 11]
  113.                 && firstBuffer[fi + 12] == secondBuffer[si + 12]
  114.                 && firstBuffer[fi + 13] == secondBuffer[si + 13]
  115.                 && firstBuffer[fi + 14] == secondBuffer[si + 14]
  116.                 && firstBuffer[fi + 15] == secondBuffer[si + 15]
  117.                 && firstBuffer[fi + 16] == secondBuffer[si + 16]
  118.                 && firstBuffer[fi + 17] == secondBuffer[si + 17]
  119.                 && firstBuffer[fi + 18] == secondBuffer[si + 18]
  120.                 && firstBuffer[fi + 19] == secondBuffer[si + 19];
  121.     }

  123.     /**
  124.      * Convert an ObjectId from raw binary representation.
  125.      *
  126.      * @param bs
  127.      *            the raw byte buffer to read from. At least 20 bytes must be
  128.      *            available within this byte array.
  129.      * @return the converted object id.
  130.      */
  131.     public static final ObjectId fromRaw(byte[] bs) {
  132.         return fromRaw(bs, 0);
  133.     }

  135.     /**
  136.      * Convert an ObjectId from raw binary representation.
  137.      *
  138.      * @param bs
  139.      *            the raw byte buffer to read from. At least 20 bytes after p
  140.      *            must be available within this byte array.
  141.      * @param p
  142.      *            position to read the first byte of data from.
  143.      * @return the converted object id.
  144.      */
  145.     public static final ObjectId fromRaw(byte[] bs, int p) {
  146.         final int a = NB.decodeInt32(bs, p);
  147.         final int b = NB.decodeInt32(bs, p + 4);
  148.         final int c = NB.decodeInt32(bs, p + 8);
  149.         final int d = NB.decodeInt32(bs, p + 12);
  150.         final int e = NB.decodeInt32(bs, p + 16);
  151.         return new ObjectId(a, b, c, d, e);
  152.     }

  154.     /**
  155.      * Convert an ObjectId from raw binary representation.
  156.      *
  157.      * @param is
  158.      *            the raw integers buffer to read from. At least 5 integers must
  159.      *            be available within this int array.
  160.      * @return the converted object id.
  161.      */
  162.     public static final ObjectId fromRaw(int[] is) {
  163.         return fromRaw(is, 0);
  164.     }

  166.     /**
  167.      * Convert an ObjectId from raw binary representation.
  168.      *
  169.      * @param is
  170.      *            the raw integers buffer to read from. At least 5 integers
  171.      *            after p must be available within this int array.
  172.      * @param p
  173.      *            position to read the first integer of data from.
  174.      * @return the converted object id.
  175.      */
  176.     public static final ObjectId fromRaw(int[] is, int p) {
  177.         return new ObjectId(is[p], is[p + 1], is[p + 2], is[p + 3], is[p + 4]);
  178.     }

  180.     /**
  181.      * Convert an ObjectId from hex characters (US-ASCII).
  182.      *
  183.      * @param buf
  184.      *            the US-ASCII buffer to read from. At least 40 bytes after
  185.      *            offset must be available within this byte array.
  186.      * @param offset
  187.      *            position to read the first character from.
  188.      * @return the converted object id.
  189.      */
  190.     public static final ObjectId fromString(byte[] buf, int offset) {
  191.         return fromHexString(buf, offset);
  192.     }

  194.     /**
  195.      * Convert an ObjectId from hex characters.
  196.      *
  197.      * @param str
  198.      *            the string to read from. Must be 40 characters long.
  199.      * @return the converted object id.
  200.      */
  201.     public static ObjectId fromString(String str) {
  202.         if (str.length() != Constants.OBJECT_ID_STRING_LENGTH) {
  203.             throw new InvalidObjectIdException(str);
  204.         }
  205.         return fromHexString(Constants.encodeASCII(str), 0);
  206.     }

  208.     private static final ObjectId fromHexString(byte[] bs, int p) {
  209.         try {
  210.             final int a = RawParseUtils.parseHexInt32(bs, p);
  211.             final int b = RawParseUtils.parseHexInt32(bs, p + 8);
  212.             final int c = RawParseUtils.parseHexInt32(bs, p + 16);
  213.             final int d = RawParseUtils.parseHexInt32(bs, p + 24);
  214.             final int e = RawParseUtils.parseHexInt32(bs, p + 32);
  215.             return new ObjectId(a, b, c, d, e);
  216.         } catch (ArrayIndexOutOfBoundsException e) {
  217.             InvalidObjectIdException e1 = new InvalidObjectIdException(bs, p,
  218.                     Constants.OBJECT_ID_STRING_LENGTH);
  219.             e1.initCause(e);
  220.             throw e1;
  221.         }
  222.     }

  224.     /**
  225.      * Construct an ObjectId from 160 bits provided in 5 words.
  226.      *
  227.      * @param new_1
  228.      *            an int
  229.      * @param new_2
  230.      *            an int
  231.      * @param new_3
  232.      *            an int
  233.      * @param new_4
  234.      *            an int
  235.      * @param new_5
  236.      *            an int
  237.      * @since 4.7
  238.      */
  239.     public ObjectId(int new_1, int new_2, int new_3, int new_4, int new_5) {
  240.         w1 = new_1;
  241.         w2 = new_2;
  242.         w3 = new_3;
  243.         w4 = new_4;
  244.         w5 = new_5;
  245.     }

  247.     /**
  248.      * Initialize this instance by copying another existing ObjectId.
  249.      * <p>
  250.      * This constructor is mostly useful for subclasses who want to extend an
  251.      * ObjectId with more properties, but initialize from an existing ObjectId
  252.      * instance acquired by other means.
  253.      *
  254.      * @param src
  255.      *            another already parsed ObjectId to copy the value out of.
  256.      */
  257.     protected ObjectId(AnyObjectId src) {
  258.         w1 = src.w1;
  259.         w2 = src.w2;
  260.         w3 = src.w3;
  261.         w4 = src.w4;
  262.         w5 = src.w5;
  263.     }

  265.     /** {@inheritDoc} */
  266.     @Override
  267.     public ObjectId toObjectId() {
  268.         return this;
  269.     }

  271.     private void writeObject(ObjectOutputStream os) throws IOException {
  272.         os.writeInt(w1);
  273.         os.writeInt(w2);
  274.         os.writeInt(w3);
  275.         os.writeInt(w4);
  276.         os.writeInt(w5);
  277.     }

  279.     private void readObject(ObjectInputStream ois) throws IOException {
  280.         w1 = ois.readInt();
  281.         w2 = ois.readInt();
  282.         w3 = ois.readInt();
  283.         w4 = ois.readInt();
  284.         w5 = ois.readInt();
  285.     }
  286. }
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