1 | /**************************************************************** |
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2 | * Licensed to the Apache Software Foundation (ASF) under one * |
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3 | * or more contributor license agreements. See the NOTICE file * |
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4 | * distributed with this work for additional information * |
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5 | * regarding copyright ownership. The ASF licenses this file * |
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6 | * to you under the Apache License, Version 2.0 (the * |
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7 | * "License"); you may not use this file except in compliance * |
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8 | * with the License. You may obtain a copy of the License at * |
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9 | * * |
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10 | * http://www.apache.org/licenses/LICENSE-2.0 * |
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11 | * * |
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12 | * Unless required by applicable law or agreed to in writing, * |
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13 | * software distributed under the License is distributed on an * |
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14 | * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * |
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15 | * KIND, either express or implied. See the License for the * |
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16 | * specific language governing permissions and limitations * |
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17 | * under the License. * |
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18 | ****************************************************************/ |
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19 | |
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20 | package org.apache.james.mime4j.codec; |
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21 | |
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22 | import java.io.FilterOutputStream; |
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23 | import java.io.IOException; |
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24 | import java.io.OutputStream; |
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25 | import java.util.HashSet; |
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26 | import java.util.Set; |
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27 | |
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28 | /** |
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29 | * This class implements section <cite>6.8. Base64 Content-Transfer-Encoding</cite> |
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30 | * from RFC 2045 <cite>Multipurpose Internet Mail Extensions (MIME) Part One: |
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31 | * Format of Internet Message Bodies</cite> by Freed and Borenstein. |
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32 | * <p> |
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33 | * Code is based on Base64 and Base64OutputStream code from Commons-Codec 1.4. |
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34 | * |
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35 | * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a> |
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36 | */ |
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37 | public class Base64OutputStream extends FilterOutputStream { |
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38 | |
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39 | // Default line length per RFC 2045 section 6.8. |
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40 | private static final int DEFAULT_LINE_LENGTH = 76; |
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41 | |
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42 | // CRLF line separator per RFC 2045 section 2.1. |
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43 | private static final byte[] CRLF_SEPARATOR = { '\r', '\n' }; |
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44 | |
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45 | // This array is a lookup table that translates 6-bit positive integer index |
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46 | // values into their "Base64 Alphabet" equivalents as specified in Table 1 |
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47 | // of RFC 2045. |
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48 | static final byte[] BASE64_TABLE = { 'A', 'B', 'C', 'D', 'E', 'F', |
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49 | 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', |
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50 | 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', |
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51 | 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', |
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52 | 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', |
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53 | '6', '7', '8', '9', '+', '/' }; |
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54 | |
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55 | // Byte used to pad output. |
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56 | private static final byte BASE64_PAD = '='; |
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57 | |
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58 | // This set contains all base64 characters including the pad character. Used |
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59 | // solely to check if a line separator contains any of these characters. |
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60 | private static final Set<Byte> BASE64_CHARS = new HashSet<Byte>(); |
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61 | |
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62 | static { |
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63 | for (byte b : BASE64_TABLE) { |
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64 | BASE64_CHARS.add(b); |
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65 | } |
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66 | BASE64_CHARS.add(BASE64_PAD); |
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67 | } |
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68 | |
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69 | // Mask used to extract 6 bits |
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70 | private static final int MASK_6BITS = 0x3f; |
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71 | |
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72 | private static final int ENCODED_BUFFER_SIZE = 2048; |
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73 | |
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74 | private final byte[] singleByte = new byte[1]; |
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75 | |
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76 | private final int lineLength; |
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77 | private final byte[] lineSeparator; |
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78 | |
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79 | private boolean closed = false; |
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80 | |
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81 | private final byte[] encoded; |
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82 | private int position = 0; |
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83 | |
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84 | private int data = 0; |
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85 | private int modulus = 0; |
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86 | |
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87 | private int linePosition = 0; |
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88 | |
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89 | /** |
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90 | * Creates a <code>Base64OutputStream</code> that writes the encoded data |
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91 | * to the given output stream using the default line length (76) and line |
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92 | * separator (CRLF). |
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93 | * |
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94 | * @param out |
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95 | * underlying output stream. |
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96 | */ |
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97 | public Base64OutputStream(OutputStream out) { |
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98 | this(out, DEFAULT_LINE_LENGTH, CRLF_SEPARATOR); |
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99 | } |
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100 | |
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101 | /** |
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102 | * Creates a <code>Base64OutputStream</code> that writes the encoded data |
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103 | * to the given output stream using the given line length and the default |
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104 | * line separator (CRLF). |
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105 | * <p> |
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106 | * The given line length will be rounded up to the nearest multiple of 4. If |
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107 | * the line length is zero then the output will not be split into lines. |
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108 | * |
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109 | * @param out |
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110 | * underlying output stream. |
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111 | * @param lineLength |
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112 | * desired line length. |
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113 | */ |
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114 | public Base64OutputStream(OutputStream out, int lineLength) { |
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115 | this(out, lineLength, CRLF_SEPARATOR); |
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116 | } |
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117 | |
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118 | /** |
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119 | * Creates a <code>Base64OutputStream</code> that writes the encoded data |
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120 | * to the given output stream using the given line length and line |
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121 | * separator. |
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122 | * <p> |
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123 | * The given line length will be rounded up to the nearest multiple of 4. If |
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124 | * the line length is zero then the output will not be split into lines and |
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125 | * the line separator is ignored. |
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126 | * <p> |
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127 | * The line separator must not include characters from the BASE64 alphabet |
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128 | * (including the padding character <code>=</code>). |
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129 | * |
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130 | * @param out |
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131 | * underlying output stream. |
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132 | * @param lineLength |
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133 | * desired line length. |
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134 | * @param lineSeparator |
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135 | * line separator to use. |
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136 | */ |
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137 | public Base64OutputStream(OutputStream out, int lineLength, |
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138 | byte[] lineSeparator) { |
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139 | super(out); |
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140 | |
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141 | if (out == null) |
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142 | throw new IllegalArgumentException(); |
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143 | if (lineLength < 0) |
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144 | throw new IllegalArgumentException(); |
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145 | checkLineSeparator(lineSeparator); |
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146 | |
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147 | this.lineLength = lineLength; |
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148 | this.lineSeparator = new byte[lineSeparator.length]; |
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149 | System.arraycopy(lineSeparator, 0, this.lineSeparator, 0, |
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150 | lineSeparator.length); |
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151 | |
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152 | this.encoded = new byte[ENCODED_BUFFER_SIZE]; |
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153 | } |
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154 | |
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155 | @Override |
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156 | public final void write(final int b) throws IOException { |
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157 | if (closed) |
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158 | throw new IOException("Base64OutputStream has been closed"); |
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159 | |
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160 | singleByte[0] = (byte) b; |
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161 | write0(singleByte, 0, 1); |
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162 | } |
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163 | |
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164 | @Override |
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165 | public final void write(final byte[] buffer) throws IOException { |
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166 | if (closed) |
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167 | throw new IOException("Base64OutputStream has been closed"); |
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168 | |
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169 | if (buffer == null) |
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170 | throw new NullPointerException(); |
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171 | |
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172 | if (buffer.length == 0) |
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173 | return; |
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174 | |
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175 | write0(buffer, 0, buffer.length); |
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176 | } |
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177 | |
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178 | @Override |
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179 | public final void write(final byte[] buffer, final int offset, |
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180 | final int length) throws IOException { |
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181 | if (closed) |
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182 | throw new IOException("Base64OutputStream has been closed"); |
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183 | |
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184 | if (buffer == null) |
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185 | throw new NullPointerException(); |
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186 | |
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187 | if (offset < 0 || length < 0 || offset + length > buffer.length) |
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188 | throw new IndexOutOfBoundsException(); |
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189 | |
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190 | if (length == 0) |
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191 | return; |
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192 | |
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193 | write0(buffer, offset, offset + length); |
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194 | } |
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195 | |
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196 | @Override |
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197 | public void flush() throws IOException { |
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198 | if (closed) |
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199 | throw new IOException("Base64OutputStream has been closed"); |
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200 | |
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201 | flush0(); |
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202 | } |
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203 | |
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204 | @Override |
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205 | public void close() throws IOException { |
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206 | if (closed) |
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207 | return; |
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208 | |
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209 | closed = true; |
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210 | close0(); |
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211 | } |
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212 | |
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213 | private void write0(final byte[] buffer, final int from, final int to) |
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214 | throws IOException { |
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215 | for (int i = from; i < to; i++) { |
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216 | data = (data << 8) | (buffer[i] & 0xff); |
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217 | |
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218 | if (++modulus == 3) { |
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219 | modulus = 0; |
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220 | |
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221 | // write line separator if necessary |
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222 | |
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223 | if (lineLength > 0 && linePosition >= lineLength) { |
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224 | // writeLineSeparator() inlined for performance reasons |
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225 | |
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226 | linePosition = 0; |
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227 | |
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228 | if (encoded.length - position < lineSeparator.length) |
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229 | flush0(); |
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230 | |
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231 | for (byte ls : lineSeparator) |
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232 | encoded[position++] = ls; |
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233 | } |
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234 | |
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235 | // encode data into 4 bytes |
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236 | |
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237 | if (encoded.length - position < 4) |
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238 | flush0(); |
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239 | |
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240 | encoded[position++] = BASE64_TABLE[(data >> 18) & MASK_6BITS]; |
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241 | encoded[position++] = BASE64_TABLE[(data >> 12) & MASK_6BITS]; |
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242 | encoded[position++] = BASE64_TABLE[(data >> 6) & MASK_6BITS]; |
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243 | encoded[position++] = BASE64_TABLE[data & MASK_6BITS]; |
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244 | |
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245 | linePosition += 4; |
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246 | } |
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247 | } |
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248 | } |
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249 | |
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250 | private void flush0() throws IOException { |
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251 | if (position > 0) { |
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252 | out.write(encoded, 0, position); |
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253 | position = 0; |
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254 | } |
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255 | } |
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256 | |
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257 | private void close0() throws IOException { |
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258 | if (modulus != 0) |
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259 | writePad(); |
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260 | |
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261 | // write line separator at the end of the encoded data |
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262 | |
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263 | if (lineLength > 0 && linePosition > 0) { |
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264 | writeLineSeparator(); |
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265 | } |
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266 | |
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267 | flush0(); |
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268 | } |
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269 | |
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270 | private void writePad() throws IOException { |
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271 | // write line separator if necessary |
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272 | |
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273 | if (lineLength > 0 && linePosition >= lineLength) { |
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274 | writeLineSeparator(); |
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275 | } |
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276 | |
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277 | // encode data into 4 bytes |
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278 | |
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279 | if (encoded.length - position < 4) |
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280 | flush0(); |
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281 | |
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282 | if (modulus == 1) { |
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283 | encoded[position++] = BASE64_TABLE[(data >> 2) & MASK_6BITS]; |
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284 | encoded[position++] = BASE64_TABLE[(data << 4) & MASK_6BITS]; |
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285 | encoded[position++] = BASE64_PAD; |
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286 | encoded[position++] = BASE64_PAD; |
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287 | } else { |
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288 | assert modulus == 2; |
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289 | encoded[position++] = BASE64_TABLE[(data >> 10) & MASK_6BITS]; |
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290 | encoded[position++] = BASE64_TABLE[(data >> 4) & MASK_6BITS]; |
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291 | encoded[position++] = BASE64_TABLE[(data << 2) & MASK_6BITS]; |
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292 | encoded[position++] = BASE64_PAD; |
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293 | } |
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294 | |
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295 | linePosition += 4; |
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296 | } |
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297 | |
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298 | private void writeLineSeparator() throws IOException { |
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299 | linePosition = 0; |
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300 | |
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301 | if (encoded.length - position < lineSeparator.length) |
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302 | flush0(); |
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303 | |
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304 | for (byte ls : lineSeparator) |
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305 | encoded[position++] = ls; |
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306 | } |
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307 | |
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308 | private void checkLineSeparator(byte[] lineSeparator) { |
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309 | if (lineSeparator.length > ENCODED_BUFFER_SIZE) |
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310 | throw new IllegalArgumentException("line separator length exceeds " |
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311 | + ENCODED_BUFFER_SIZE); |
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312 | |
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313 | for (byte b : lineSeparator) { |
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314 | if (BASE64_CHARS.contains(b)) { |
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315 | throw new IllegalArgumentException( |
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316 | "line separator must not contain base64 character '" |
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317 | + (char) (b & 0xff) + "'"); |
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318 | } |
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319 | } |
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320 | } |
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321 | } |
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