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 
26 package sun.rmi.log;
27 
28 import java.io.*;
29 
30 public
31 class 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      */
LogInputStream(InputStream in, int length)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      */
read()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      */
read(byte b[])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      */
read(byte b[], int off, int len)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      */
skip(long n)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      */
available()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      */
close()124     public void close() {
125         length = 0;
126     }
127 
128     /**
129      * Closes the stream when garbage is collected.
130      */
131     @SuppressWarnings("deprecation")
finalize()132     protected void finalize() throws IOException {
133         close();
134     }
135 }
136