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 InputStream}, limiting the number of bytes which can be
55 * read.
56 *
57 * This class was copied and modifed from the Google Guava 16.0. Differently from
58 * the original Guava code, when a caller tries to read from this stream past
59 * the given limit and the wrapped stream hasn't yet reached its EOF this class
60 * 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 @Override
84 public int available() throws IOException {
85 return (int) Math.min(in.available(), left);
86 }
87
88 // it's okay to mark even if mark isn't supported, as reset won't work
89 @Override
90 public synchronized void mark(int readLimit) {
91 in.mark(readLimit);
92 mark = left;
93 }
94
95 @Override
96 public int read() throws IOException {
97 if (left == 0) {
98 if (in.available() == 0)
99 return -1;
100 else
101 limitExceeded();
102 }
103
104 int result = in.read();
105 if (result != -1)
106 --left;
107 return result;
108 }
109
110 @Override
111 public int read(byte[] b, int off, int len) throws IOException {
112 if (left == 0) {
113 if (in.available() == 0)
114 return -1;
115 else
116 limitExceeded();
117 }
118
119 len = (int) Math.min(len, left);
120 int result = in.read(b, off, len);
121 if (result != -1)
122 left -= result;
123 return result;
124 }
125
126 @Override
127 public synchronized void reset() throws IOException {
128 if (!in.markSupported())
129 throw new IOException(JGitText.get().unsupportedMark);
130
131 if (mark == -1)
132 throw new IOException(JGitText.get().unsetMark);
133
134 in.reset();
135 left = mark;
136 }
137
138 @Override
139 public long skip(long n) throws IOException {
140 n = Math.min(n, left);
141 long skipped = in.skip(n);
142 left -= skipped;
143 return skipped;
144 }
145
146 /**
147 * Called when trying to read past the given {@link #limit} and the wrapped
148 * InputStream {@link #in} hasn't yet reached its EOF
149 *
150 * @throws IOException
151 * subclasses can throw an IOException when the limit is exceeded.
152 * The throws IOException will be forwarded back to the caller of
153 * the read method which read the stream past the limit.
154 */
155 protected abstract void limitExceeded() throws IOException;
156 }