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| 1 | /* | ||
| 2 | * Copyright (c) 1996, 2006, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | package java.util.zip; | ||
| 27 | |||
| 28 | import java.io.FilterInputStream; | ||
| 29 | import java.io.InputStream; | ||
| 30 | import java.io.IOException; | ||
| 31 | |||
| 32 | /** | ||
| 33 | * An input stream that also maintains a checksum of the data being read. | ||
| 34 | * The checksum can then be used to verify the integrity of the input data. | ||
| 35 | * | ||
| 36 | * @see Checksum | ||
| 37 | * @author David Connelly | ||
| 38 | */ | ||
| 39 | public | ||
| 40 | class CheckedInputStream extends FilterInputStream { | ||
| 41 | private Checksum cksum; | ||
| 42 | |||
| 43 | /** | ||
| 44 | * Creates an input stream using the specified Checksum. | ||
| 45 | * @param in the input stream | ||
| 46 | * @param cksum the Checksum | ||
| 47 | */ | ||
| 48 | public CheckedInputStream(InputStream in, Checksum cksum) { | ||
| 49 | super(in); | ||
| 50 | this.cksum = cksum; | ||
| 51 | } | ||
| 52 | |||
| 53 | /** | ||
| 54 | * Reads a byte. Will block if no input is available. | ||
| 55 | * @return the byte read, or -1 if the end of the stream is reached. | ||
| 56 | * @exception IOException if an I/O error has occurred | ||
| 57 | */ | ||
| 58 | public int read() throws IOException { | ||
| 59 | int b = in.read(); | ||
| 60 | if (b != -1) { | ||
| 61 | cksum.update(b); | ||
| 62 | } | ||
| 63 | return b; | ||
| 64 | } | ||
| 65 | |||
| 66 | /** | ||
| 67 | * Reads into an array of bytes. If <code>len</code> is not zero, the method | ||
| 68 | * blocks until some input is available; otherwise, no | ||
| 69 | * bytes are read and <code>0</code> is returned. | ||
| 70 | * @param buf the buffer into which the data is read | ||
| 71 | * @param off the start offset in the destination array <code>b</code> | ||
| 72 | * @param len the maximum number of bytes read | ||
| 73 | * @return the actual number of bytes read, or -1 if the end | ||
| 74 | * of the stream is reached. | ||
| 75 | * @exception NullPointerException If <code>buf</code> is <code>null</code>. | ||
| 76 | * @exception IndexOutOfBoundsException If <code>off</code> is negative, | ||
| 77 | * <code>len</code> is negative, or <code>len</code> is greater than | ||
| 78 | * <code>buf.length - off</code> | ||
| 79 | * @exception IOException if an I/O error has occurred | ||
| 80 | */ | ||
| 81 | public int read(byte[] buf, int off, int len) throws IOException { | ||
| 82 | len = in.read(buf, off, len); | ||
| 83 | if (len != -1) { | ||
| 84 | cksum.update(buf, off, len); | ||
| 85 | } | ||
| 86 | return len; | ||
| 87 | } | ||
| 88 | |||
| 89 | /** | ||
| 90 | * Skips specified number of bytes of input. | ||
| 91 | * @param n the number of bytes to skip | ||
| 92 | * @return the actual number of bytes skipped | ||
| 93 | * @exception IOException if an I/O error has occurred | ||
| 94 | */ | ||
| 95 | public long skip(long n) throws IOException { | ||
| 96 | byte[] buf = new byte[512]; | ||
| 97 | long total = 0; | ||
| 98 | while (total < n) { | ||
| 99 | long len = n - total; | ||
| 100 | len = read(buf, 0, len < buf.length ? (int)len : buf.length); | ||
| 101 | if (len == -1) { | ||
| 102 | return total; | ||
| 103 | } | ||
| 104 | total += len; | ||
| 105 | } | ||
| 106 | return total; | ||
| 107 | } | ||
| 108 | |||
| 109 | /** | ||
| 110 | * Returns the Checksum for this input stream. | ||
| 111 | * @return the Checksum value | ||
| 112 | */ | ||
| 113 | public Checksum getChecksum() { | ||
| 114 | return cksum; | ||
| 115 | } | ||
| 116 | } | ||