1/*
2 * Copyright (c) 1997, 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 sun.rmi.log;
27
28import java.io.*;
29
30public
31class LogInputStream extends InputStream {
32    private InputStream in;
33    private int length;
34
35    /**
36     * Creates a log input file with the specified system dependent
37     * file descriptor.
38     * @param in the system dependent file descriptor
39     * @param length the total number of bytes allowed to be read
40     * @exception IOException If an I/O error has occurred.
41     */
42    public LogInputStream(InputStream in, int length) throws IOException {
43        this.in = in;
44        this.length = length;
45    }
46
47    /**
48     * Reads a byte of data. This method will block if no input is
49     * available.
50     * @return  the byte read, or -1 if the end of the log or end of the
51     *          stream is reached.
52     * @exception IOException If an I/O error has occurred.
53     */
54    public int read() throws IOException {
55        if (length == 0)
56            return -1;
57        int c = in.read();
58        length = (c != -1) ? length - 1 : 0;
59        return c;
60    }
61
62    /**
63     * Reads data into an array of bytes.
64     * This method blocks until some input is available.
65     * @param b the buffer into which the data is read
66     * @return  the actual number of bytes read, or -1 if the end of the log
67     *          or end of the stream is reached.
68     * @exception IOException If an I/O error has occurred.
69     */
70    public int read(byte b[]) throws IOException {
71        return read(b, 0, b.length);
72    }
73
74    /**
75     * Reads data into an array of bytes.
76     * This method blocks until some input is available.
77     * @param b the buffer into which the data is read
78     * @param off the start offset of the data
79     * @param len the maximum number of bytes read
80     * @return  the actual number of bytes read, or -1 if the end of the log or
81     *          end of the stream is reached.
82     * @exception IOException If an I/O error has occurred.
83     */
84    public int read(byte b[], int off, int len) throws IOException {
85        if (length == 0)
86            return -1;
87        len = (length < len) ? length : len;
88        int n = in.read(b, off, len);
89        length = (n != -1) ? length - n : 0;
90        return n;
91    }
92
93    /**
94     * Skips n bytes of input.
95     * @param n the number of bytes to be skipped
96     * @return  the actual number of bytes skipped.
97     * @exception IOException If an I/O error has occurred.
98     */
99    public long skip(long n) throws IOException {
100        if (n > Integer.MAX_VALUE)
101            throw new IOException("Too many bytes to skip - " + n);
102        if (length == 0)
103            return 0;
104        n = (length < n) ? length : n;
105        n = in.skip(n);
106        length -= n;
107        return n;
108    }
109
110    /**
111     * Returns the number of bytes that can be read without blocking.
112     * @return  the number of available bytes, which is initially
113     *          equal to the file size.
114     */
115    public int available() throws IOException {
116        int avail = in.available();
117        return (length < avail) ? length : avail;
118    }
119
120    /**
121     * Closes the input stream.  No further input can be read.
122     * the stream.
123     */
124    public void close() {
125        length = 0;
126    }
127
128    /**
129     * Closes the stream when garbage is collected.
130     */
131    @SuppressWarnings("deprecation")
132    protected void finalize() throws IOException {
133        close();
134    }
135}
136