fix e621 descriptions
[nikiroo-utils.git] / src / be / nikiroo / utils / streams / Base64InputStream.java
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1/*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package be.nikiroo.utils.streams;
18
19import java.io.FilterInputStream;
20import java.io.IOException;
21import java.io.InputStream;
22
23/**
24 * An InputStream that does Base64 decoding on the data read through
25 * it.
26 */
27public class Base64InputStream extends FilterInputStream {
28 private final Base64.Coder coder;
29
30 private static byte[] EMPTY = new byte[0];
31
32 private static final int BUFFER_SIZE = 2048;
33 private boolean eof;
34 private byte[] inputBuffer;
35 private int outputStart;
36 private int outputEnd;
37
38 /**
39 * An InputStream that performs Base64 decoding on the data read
40 * from the wrapped stream.
41 *
42 * @param in the InputStream to read the source data from
43 */
44 public Base64InputStream(InputStream in) {
45 this(in, false);
46 }
47
48 /**
49 * Performs Base64 encoding or decoding on the data read from the
50 * wrapped InputStream.
51 *
52 * @param in the InputStream to read the source data from
53 * @param flags bit flags for controlling the decoder; see the
54 * constants in {@link Base64}
55 * @param encode true to encode, false to decode
56 *
57 * @hide
58 */
59 public Base64InputStream(InputStream in, boolean encode) {
60 super(in);
61 eof = false;
62 inputBuffer = new byte[BUFFER_SIZE];
63 if (encode) {
64 coder = new Base64.Encoder(Base64.NO_WRAP, null);
65 } else {
66 coder = new Base64.Decoder(Base64.NO_WRAP, null);
67 }
68 coder.output = new byte[coder.maxOutputSize(BUFFER_SIZE)];
69 outputStart = 0;
70 outputEnd = 0;
71 }
72
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73 @Override
74 public boolean markSupported() {
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75 return false;
76 }
77
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78 @SuppressWarnings("sync-override")
79 @Override
80 public void mark(int readlimit) {
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81 throw new UnsupportedOperationException();
82 }
83
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84 @SuppressWarnings("sync-override")
85 @Override
86 public void reset() {
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87 throw new UnsupportedOperationException();
88 }
89
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90 @Override
91 public void close() throws IOException {
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92 in.close();
93 inputBuffer = null;
94 }
95
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96 @Override
97 public int available() {
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98 return outputEnd - outputStart;
99 }
100
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101 @Override
102 public long skip(long n) throws IOException {
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103 if (outputStart >= outputEnd) {
104 refill();
105 }
106 if (outputStart >= outputEnd) {
107 return 0;
108 }
109 long bytes = Math.min(n, outputEnd-outputStart);
110 outputStart += bytes;
111 return bytes;
112 }
113
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114 @Override
115 public int read() throws IOException {
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116 if (outputStart >= outputEnd) {
117 refill();
118 }
119 if (outputStart >= outputEnd) {
120 return -1;
f28a134e 121 }
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122
123 return coder.output[outputStart++] & 0xff;
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124 }
125
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126 @Override
127 public int read(byte[] b, int off, int len) throws IOException {
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128 if (outputStart >= outputEnd) {
129 refill();
130 }
131 if (outputStart >= outputEnd) {
132 return -1;
133 }
134 int bytes = Math.min(len, outputEnd-outputStart);
135 System.arraycopy(coder.output, outputStart, b, off, bytes);
136 outputStart += bytes;
137 return bytes;
138 }
139
140 /**
141 * Read data from the input stream into inputBuffer, then
142 * decode/encode it into the empty coder.output, and reset the
143 * outputStart and outputEnd pointers.
144 */
145 private void refill() throws IOException {
146 if (eof) return;
147 int bytesRead = in.read(inputBuffer);
148 boolean success;
149 if (bytesRead == -1) {
150 eof = true;
151 success = coder.process(EMPTY, 0, 0, true);
152 } else {
153 success = coder.process(inputBuffer, 0, bytesRead, false);
154 }
155 if (!success) {
156 throw new IOException("bad base-64");
157 }
158 outputEnd = coder.op;
159 outputStart = 0;
160 }
161}