| /* CheckedInputStream.java - Compute checksum of data being read |
| Copyright (C) 1999, 2000, 2004 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath 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; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath 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. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package java.util.zip; |
| |
| import java.io.FilterInputStream; |
| import java.io.IOException; |
| import java.io.InputStream; |
| |
| /* Written using on-line Java Platform 1.2 API Specification |
| * and JCL book. |
| * Believed complete and correct. |
| */ |
| |
| /** |
| * InputStream that computes a checksum of the data being read using a |
| * supplied Checksum object. |
| * |
| * @see Checksum |
| * |
| * @author Tom Tromey |
| * @date May 17, 1999 |
| */ |
| public class CheckedInputStream extends FilterInputStream |
| { |
| /** |
| * Creates a new CheckInputStream on top of the supplied OutputStream |
| * using the supplied Checksum. |
| */ |
| public CheckedInputStream (InputStream in, Checksum sum) |
| { |
| super (in); |
| this.sum = sum; |
| } |
| |
| /** |
| * Returns the Checksum object used. To get the data checksum computed so |
| * far call <code>getChecksum.getValue()</code>. |
| */ |
| public Checksum getChecksum () |
| { |
| return sum; |
| } |
| |
| /** |
| * Reads one byte, updates the checksum and returns the read byte |
| * (or -1 when the end of file was reached). |
| */ |
| public int read () throws IOException |
| { |
| int x = in.read(); |
| if (x != -1) |
| sum.update(x); |
| return x; |
| } |
| |
| /** |
| * Reads at most len bytes in the supplied buffer and updates the checksum |
| * with it. Returns the number of bytes actually read or -1 when the end |
| * of file was reached. |
| */ |
| public int read (byte[] buf, int off, int len) throws IOException |
| { |
| int r = in.read(buf, off, len); |
| if (r != -1) |
| sum.update(buf, off, r); |
| return r; |
| } |
| |
| /** |
| * Skips n bytes by reading them in a temporary buffer and updating the |
| * the checksum with that buffer. Returns the actual number of bytes skiped |
| * which can be less then requested when the end of file is reached. |
| */ |
| public long skip (long n) throws IOException |
| { |
| if (n == 0) |
| return 0; |
| |
| int min = (int) Math.min(n, 1024); |
| byte[] buf = new byte[min]; |
| |
| long s = 0; |
| while (n > 0) |
| { |
| int r = in.read(buf, 0, min); |
| if (r == -1) |
| break; |
| n -= r; |
| s += r; |
| min = (int) Math.min(n, 1024); |
| sum.update(buf, 0, r); |
| } |
| |
| return s; |
| } |
| |
| /** The checksum object. */ |
| private Checksum sum; |
| } |