1 /*
2 * Copyright (c) 1997, 1999, 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 */
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 protected void finalize() throws IOException {
132 close();
133 }
134 }