1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * https://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.codec.binary;
19
20 import static org.apache.commons.codec.binary.BaseNCodec.EOF;
21
22 import java.io.FilterInputStream;
23 import java.io.IOException;
24 import java.io.InputStream;
25 import java.util.Objects;
26
27 import org.apache.commons.codec.binary.BaseNCodec.Context;
28
29 /**
30 * Abstract superclass for Base-N input streams.
31 *
32 * @since 1.5
33 */
34 public class BaseNCodecInputStream extends FilterInputStream {
35
36 private final BaseNCodec baseNCodec;
37
38 private final boolean doEncode;
39
40 private final byte[] singleByte = new byte[1];
41
42 private final byte[] buf;
43
44 private final Context context = new Context();
45
46 /**
47 * Constructs a new instance.
48 *
49 * @param inputStream the input stream
50 * @param baseNCodec the codec
51 * @param doEncode set to true to perform encoding, else decoding
52 */
53 protected BaseNCodecInputStream(final InputStream inputStream, final BaseNCodec baseNCodec, final boolean doEncode) {
54 super(inputStream);
55 this.doEncode = doEncode;
56 this.baseNCodec = baseNCodec;
57 this.buf = new byte[doEncode ? 4096 : 8192];
58 }
59
60 /**
61 * {@inheritDoc}
62 *
63 * @return {@code 0} if the {@link InputStream} has reached {@code EOF},
64 * {@code 1} otherwise
65 * @since 1.7
66 */
67 @Override
68 public int available() throws IOException {
69 // Note: The logic is similar to the InflaterInputStream:
70 // as long as we have not reached EOF, indicate that there is more
71 // data available. As we do not know for sure how much data is left,
72 // just return 1 as a safe guess.
73 return context.eof ? 0 : 1;
74 }
75
76 /**
77 * Returns true if decoding behavior is strict. Decoding will raise an
78 * {@link IllegalArgumentException} if trailing bits are not part of a valid encoding.
79 *
80 * <p>
81 * The default is false for lenient encoding. Decoding will compose trailing bits
82 * into 8-bit bytes and discard the remainder.
83 * </p>
84 *
85 * @return true if using strict decoding
86 * @since 1.15
87 */
88 public boolean isStrictDecoding() {
89 return baseNCodec.isStrictDecoding();
90 }
91
92 /**
93 * Marks the current position in this input stream.
94 * <p>
95 * The {@link #mark} method of {@link BaseNCodecInputStream} does nothing.
96 * </p>
97 *
98 * @param readLimit the maximum limit of bytes that can be read before the mark position becomes invalid.
99 * @see #markSupported()
100 * @since 1.7
101 */
102 @Override
103 public synchronized void mark(final int readLimit) {
104 // noop
105 }
106
107 /**
108 * {@inheritDoc}
109 *
110 * @return Always returns {@code false}
111 */
112 @Override
113 public boolean markSupported() {
114 return false; // not an easy job to support marks
115 }
116
117 /**
118 * Reads one {@code byte} from this input stream.
119 *
120 * @return the byte as an integer in the range 0 to 255. Returns -1 if EOF has been reached.
121 * @throws IOException
122 * if an I/O error occurs.
123 */
124 @Override
125 public int read() throws IOException {
126 int r = read(singleByte, 0, 1);
127 while (r == 0) {
128 r = read(singleByte, 0, 1);
129 }
130 if (r > 0) {
131 final byte b = singleByte[0];
132 return b < 0 ? 256 + b : b;
133 }
134 return EOF;
135 }
136
137 /**
138 * Attempts to read {@code len} bytes into the specified {@code b} array starting at {@code offset}
139 * from this InputStream.
140 *
141 * @param array
142 * destination byte array
143 * @param offset
144 * where to start writing the bytes
145 * @param len
146 * maximum number of bytes to read
147 *
148 * @return number of bytes read
149 * @throws IOException
150 * if an I/O error occurs.
151 * @throws NullPointerException
152 * if the byte array parameter is null
153 * @throws IndexOutOfBoundsException
154 * if offset, len or buffer size are invalid
155 */
156 @Override
157 public int read(final byte[] array, final int offset, final int len) throws IOException {
158 Objects.requireNonNull(array, "array");
159 if (offset < 0 || len < 0 || offset > array.length || offset + len > array.length) {
160 throw new IndexOutOfBoundsException();
161 }
162 if (len == 0) {
163 return 0;
164 }
165 int readLen = 0;
166 /*
167 Rationale for while-loop on (readLen == 0):
168 -----
169 Base32.readResults() usually returns > 0 or EOF (-1). In the
170 rare case where it returns 0, we just keep trying.
171
172 This is essentially an undocumented contract for InputStream
173 implementors that want their code to work properly with
174 java.io.InputStreamReader, since the latter hates it when
175 InputStream.read(byte[]) returns a zero. Unfortunately our
176 readResults() call must return 0 if a large amount of the data
177 being decoded was non-base32, so this while-loop enables proper
178 interop with InputStreamReader for that scenario.
179 -----
180 This is a fix for CODEC-101
181 */
182 // Attempt to read the request length
183 while (readLen < len) {
184 if (!baseNCodec.hasData(context)) {
185 // Obtain more data.
186 // buf is reused across calls to read to avoid repeated allocations
187 final int c = in.read(buf);
188 if (doEncode) {
189 baseNCodec.encode(buf, 0, c, context);
190 } else {
191 baseNCodec.decode(buf, 0, c, context);
192 }
193 }
194 final int read = baseNCodec.readResults(array, offset + readLen, len - readLen, context);
195 if (read < 0) {
196 // Return the amount read or EOF
197 return readLen != 0 ? readLen : -1;
198 }
199 readLen += read;
200 }
201 return readLen;
202 }
203
204 /**
205 * Repositions this stream to the position at the time the mark method was last called on this input stream.
206 * <p>
207 * The {@link #reset} method of {@link BaseNCodecInputStream} does nothing except throw an {@link IOException}.
208 * </p>
209 *
210 * @throws IOException if this method is invoked
211 * @since 1.7
212 */
213 @Override
214 public synchronized void reset() throws IOException {
215 throw new IOException("mark/reset not supported");
216 }
217
218 /**
219 * {@inheritDoc}
220 *
221 * @throws IllegalArgumentException if the provided skip length is negative
222 * @since 1.7
223 */
224 @Override
225 public long skip(final long n) throws IOException {
226 if (n < 0) {
227 throw new IllegalArgumentException("Negative skip length: " + n);
228 }
229 // skip in chunks of 512 bytes
230 final byte[] b = new byte[512];
231 long todo = n;
232 while (todo > 0) {
233 int len = (int) Math.min(b.length, todo);
234 len = this.read(b, 0, len);
235 if (len == EOF) {
236 break;
237 }
238 todo -= len;
239 }
240 return n - todo;
241 }
242 }