Mercurial > jhg
view src/org/tmatesoft/hg/internal/DigestHelper.java @ 188:facfd8518367
[4] IllegalArgumentException: Underflow. Legitimate attempt to read 0 bytes lead to exception
author | Artem Tikhomirov <tikhomirov.artem@gmail.com> |
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date | Thu, 14 Apr 2011 02:46:35 +0200 (2011-04-14) |
parents | a3a2e5deb320 |
children | 0a2f445de774 |
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/* * Copyright (c) 2010-2011 TMate Software Ltd * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; version 2 of the License. * * This program 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 General Public License for more details. * * For information on how to redistribute this software under * the terms of a license other than GNU General Public License * contact TMate Software at support@hg4j.com */ package org.tmatesoft.hg.internal; import java.io.IOException; import java.io.InputStream; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import org.tmatesoft.hg.core.Nodeid; /** * <pre> * DigestHelper dh; * dh.sha1(...).asHexString(); * or * dh = dh.sha1(...); * nodeid.equalsTo(dh.asBinary()); * </pre> * * @author Artem Tikhomirov * @author TMate Software Ltd. */ public class DigestHelper { private MessageDigest sha1; private byte[] digest; public DigestHelper() { } private MessageDigest getSHA1() { if (sha1 == null) { try { sha1 = MessageDigest.getInstance("SHA-1"); } catch (NoSuchAlgorithmException ex) { // could hardly happen, JDK from Sun always has sha1. ex.printStackTrace(); // FIXME log error } } return sha1; } public DigestHelper sha1(Nodeid nodeid1, Nodeid nodeid2, byte[] data) { return sha1(nodeid1.toByteArray(), nodeid2.toByteArray(), data); } // sha1_digest(min(p1,p2) ++ max(p1,p2) ++ final_text) public DigestHelper sha1(byte[] nodeidParent1, byte[] nodeidParent2, byte[] data) { MessageDigest alg = getSHA1(); if ((nodeidParent1[0] & 0x00FF) < (nodeidParent2[0] & 0x00FF)) { alg.update(nodeidParent1); alg.update(nodeidParent2); } else { alg.update(nodeidParent2); alg.update(nodeidParent1); } digest = alg.digest(data); assert digest.length == 20; return this; } public String asHexString() { if (digest == null) { throw new IllegalStateException("Shall init with sha1() call first"); } return toHexString(digest, 0, digest.length); } // by reference, be careful not to modify (or #clone() if needed) public byte[] asBinary() { if (digest == null) { throw new IllegalStateException("Shall init with sha1() call first"); } return digest; } // XXX perhaps, digest functions should throw an exception, as it's caller responsibility to deal with eof, etc public DigestHelper sha1(InputStream is /*ByteBuffer*/) throws IOException { MessageDigest alg = getSHA1(); byte[] buf = new byte[1024]; int c; while ((c = is.read(buf)) != -1) { alg.update(buf, 0, c); } digest = alg.digest(); return this; } public DigestHelper sha1(CharSequence... seq) { MessageDigest alg = getSHA1(); for (CharSequence s : seq) { byte[] b = s.toString().getBytes(); alg.update(b); } digest = alg.digest(); return this; } public static String toHexString(byte[] data, final int offset, final int count) { char[] result = new char[count << 1]; final String hexDigits = "0123456789abcdef"; final int end = offset+count; for (int i = offset, j = 0; i < end; i++) { result[j++] = hexDigits.charAt((data[i] >>> 4) & 0x0F); result[j++] = hexDigits.charAt(data[i] & 0x0F); } return new String(result); } }