1/*
2 * Copyright (c) 2000, 2017, 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
26package com.sun.imageio.plugins.common;
27
28import java.io.IOException;
29import javax.imageio.stream.ImageInputStreamImpl;
30import javax.imageio.stream.ImageInputStream;
31
32public final class SubImageInputStream extends ImageInputStreamImpl {
33
34    ImageInputStream stream;
35    long startingPos;
36    int startingLength;
37    int length;
38
39    public SubImageInputStream(ImageInputStream stream, int length)
40        throws IOException {
41        this.stream = stream;
42        this.startingPos = stream.getStreamPosition();
43        this.startingLength = this.length = length;
44    }
45
46    public int read() throws IOException {
47        if (length == 0) { // Local EOF
48            return -1;
49        } else {
50            --length;
51            return stream.read();
52        }
53    }
54
55    public int read(byte[] b, int off, int len) throws IOException {
56        if (length == 0) { // Local EOF
57            return -1;
58        }
59
60        len = Math.min(len, length);
61        int bytes = stream.read(b, off, len);
62        length -= bytes;
63        return bytes;
64    }
65
66    public long length() {
67        return startingLength;
68    }
69
70    public void seek(long pos) throws IOException {
71        stream.seek(pos - startingPos);
72        streamPos = pos;
73    }
74
75    @SuppressWarnings("deprecation")
76    protected void finalize() throws Throwable {
77        // Empty finalizer (for improved performance; no need to call
78        // super.finalize() in this case)
79    }
80}
81