1 /*
2 * Copyright (C) 2007 The Guava Authors
3 * Copyright (C) 2014, Sasa Zivkov <sasa.zivkov@sap.com>, SAP AG
4 * and other copyright owners as documented in the project's IP log.
5 *
6 * This program and the accompanying materials are made available
7 * under the terms of the Eclipse Distribution License v1.0 which
8 * accompanies this distribution, is reproduced below, and is
9 * available at http://www.eclipse.org/org/documents/edl-v10.php
10 *
11 * All rights reserved.
12 *
13 * Redistribution and use in source and binary forms, with or
14 * without modification, are permitted provided that the following
15 * conditions are met:
16 *
17 * - Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 *
20 * - Redistributions in binary form must reproduce the above
21 * copyright notice, this list of conditions and the following
22 * disclaimer in the documentation and/or other materials provided
23 * with the distribution.
24 *
25 * - Neither the name of the Eclipse Foundation, Inc. nor the
26 * names of its contributors may be used to endorse or promote
27 * products derived from this software without specific prior
28 * written permission.
29 *
30 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
31 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
32 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
33 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
34 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
35 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
36 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
37 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
38 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
39 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
40 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
41 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
42 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
43 */
44
45 package org.eclipse.jgit.util.io;
46
47 import java.io.FilterInputStream;
48 import java.io.IOException;
49 import java.io.InputStream;
50
51 import org.eclipse.jgit.internal.JGitText;
52
53 /**
54 * Wraps a {@link java.io.InputStream}, limiting the number of bytes which can
55 * be read.
56 *
57 * This class was copied and modifed from the Google Guava 16.0. Differently
58 * from the original Guava code, when a caller tries to read from this stream
59 * past the given limit and the wrapped stream hasn't yet reached its EOF this
60 * class will call the limitExceeded method instead of returning EOF.
61 *
62 * @since 3.3
63 */
64 public abstract class LimitedInputStream extends FilterInputStream {
65
66 private long left;
67 /** Max number of bytes to be read from the wrapped stream */
68 protected final long limit;
69 private long mark = -1;
70
71 /**
72 * Create a new LimitedInputStream
73 *
74 * @param in an InputStream
75 * @param limit max number of bytes to read from the InputStream
76 */
77 protected LimitedInputStream(InputStream in, long limit) {
78 super(in);
79 left = limit;
80 this.limit = limit;
81 }
82
83 /** {@inheritDoc} */
84 @Override
85 public int available() throws IOException {
86 return (int) Math.min(in.available(), left);
87 }
88
89 // it's okay to mark even if mark isn't supported, as reset won't work
90 /** {@inheritDoc} */
91 @Override
92 public synchronized void mark(int readLimit) {
93 in.mark(readLimit);
94 mark = left;
95 }
96
97 /** {@inheritDoc} */
98 @Override
99 public int read() throws IOException {
100 if (left == 0) {
101 if (in.available() == 0) {
102 return -1;
103 }
104 limitExceeded();
105 }
106
107 int result = in.read();
108 if (result != -1) {
109 --left;
110 }
111 return result;
112 }
113
114 /** {@inheritDoc} */
115 @Override
116 public int read(byte[] b, int off, int len) throws IOException {
117 if (left == 0) {
118 if (in.available() == 0) {
119 return -1;
120 }
121 limitExceeded();
122 }
123
124 len = (int) Math.min(len, left);
125 int result = in.read(b, off, len);
126 if (result != -1) {
127 left -= result;
128 }
129 return result;
130 }
131
132 /** {@inheritDoc} */
133 @Override
134 public synchronized void reset() throws IOException {
135 if (!in.markSupported())
136 throw new IOException(JGitText.get().unsupportedMark);
137
138 if (mark == -1)
139 throw new IOException(JGitText.get().unsetMark);
140
141 in.reset();
142 left = mark;
143 }
144
145 /** {@inheritDoc} */
146 @Override
147 public long skip(long n) throws IOException {
148 n = Math.min(n, left);
149 long skipped = in.skip(n);
150 left -= skipped;
151 return skipped;
152 }
153
154 /**
155 * Called when trying to read past the given {@link #limit} and the wrapped
156 * InputStream {@link #in} hasn't yet reached its EOF
157 *
158 * @throws java.io.IOException
159 * subclasses can throw an {@link java.io.IOException} when the
160 * limit is exceeded. The throws java.io.IOException will be
161 * forwarded back to the caller of the read method which read
162 * the stream past the limit.
163 */
164 protected abstract void limitExceeded() throws IOException;
165 }