1 | // License: GPL. For details, see LICENSE file.
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2 | package org.openstreetmap.josm.tools;
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3 |
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4 | import java.io.ByteArrayOutputStream;
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5 | import java.io.File;
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6 | import java.io.FileInputStream;
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7 | import java.io.IOException;
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8 | import java.io.InputStream;
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9 | import java.text.ParseException;
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10 |
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11 | /**
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12 | * Represents a Windows shortcut (typically visible to Java only as a '.lnk' file).
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13 | *
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14 | * Retrieved 2011-09-23 from http://stackoverflow.com/questions/309495/windows-shortcut-lnk-parser-in-java/672775#672775
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15 | *
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16 | * Written by: (the stack overflow users, obviously!)
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17 | * Apache Commons VFS dependency removed by crysxd (why were we using that!?) https://github.com/crysxd
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18 | * Headerified, refactored and commented by Code Bling http://stackoverflow.com/users/675721/code-bling
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19 | * Network file support added by Stefan Cordes http://stackoverflow.com/users/81330/stefan-cordes
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20 | * Adapted by Sam Brightman http://stackoverflow.com/users/2492/sam-brightman
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21 | * Based on information in 'The Windows Shortcut File Format' by Jesse Hager <jessehager@iname.com>
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22 | * And somewhat based on code from the book 'Swing Hacks: Tips and Tools for Killer GUIs'
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23 | * by Joshua Marinacci and Chris Adamson
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24 | * ISBN: 0-596-00907-0
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25 | * http://www.oreilly.com/catalog/swinghks/
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26 | * @since 13692
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27 | */
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28 | public class WindowsShortcut {
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29 | private boolean isDirectory;
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30 | private boolean isLocal;
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31 | private String realFile;
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32 |
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33 | /**
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34 | * Provides a quick test to see if this could be a valid link !
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35 | * If you try to instantiate a new WindowShortcut and the link is not valid,
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36 | * Exceptions may be thrown and Exceptions are extremely slow to generate,
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37 | * therefore any code needing to loop through several files should first check this.
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38 | *
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39 | * @param file the potential link
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40 | * @return true if may be a link, false otherwise
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41 | * @throws IOException if an IOException is thrown while reading from the file
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42 | */
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43 | public static boolean isPotentialValidLink(File file) throws IOException {
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44 | final int minimum_length = 0x64;
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45 | boolean isPotentiallyValid = false;
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46 | try (InputStream fis = new FileInputStream(file)) {
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47 | isPotentiallyValid = file.isFile()
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48 | && file.getName().toLowerCase().endsWith(".lnk")
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49 | && fis.available() >= minimum_length
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50 | && isMagicPresent(getBytes(fis, 32));
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51 | }
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52 | return isPotentiallyValid;
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53 | }
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54 |
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55 | /**
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56 | * Constructs a new {@code WindowsShortcut}
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57 | * @param file file
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58 | * @throws IOException if an I/O error occurs
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59 | * @throws ParseException if a parsing error occurs
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60 | */
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61 | public WindowsShortcut(File file) throws IOException, ParseException {
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62 | try (InputStream in = new FileInputStream(file)) {
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63 | parseLink(getBytes(in));
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64 | }
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65 | }
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66 |
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67 | /**
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68 | * @return the name of the filesystem object pointed to by this shortcut
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69 | */
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70 | public String getRealFilename() {
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71 | return realFile;
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72 | }
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73 |
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74 | /**
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75 | * Tests if the shortcut points to a local resource.
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76 | * @return true if the 'local' bit is set in this shortcut, false otherwise
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77 | */
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78 | public boolean isLocal() {
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79 | return isLocal;
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80 | }
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81 |
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82 | /**
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83 | * Tests if the shortcut points to a directory.
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84 | * @return true if the 'directory' bit is set in this shortcut, false otherwise
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85 | */
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86 | public boolean isDirectory() {
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87 | return isDirectory;
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88 | }
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89 |
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90 | /**
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91 | * Gets all the bytes from an InputStream
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92 | * @param in the InputStream from which to read bytes
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93 | * @return array of all the bytes contained in 'in'
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94 | * @throws IOException if an IOException is encountered while reading the data from the InputStream
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95 | */
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96 | private static byte[] getBytes(InputStream in) throws IOException {
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97 | return getBytes(in, null);
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98 | }
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99 |
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100 | /**
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101 | * Gets up to max bytes from an InputStream
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102 | * @param in the InputStream from which to read bytes
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103 | * @param max maximum number of bytes to read
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104 | * @return array of all the bytes contained in 'in'
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105 | * @throws IOException if an IOException is encountered while reading the data from the InputStream
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106 | */
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107 | private static byte[] getBytes(InputStream in, Integer max) throws IOException {
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108 | // read the entire file into a byte buffer
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109 | ByteArrayOutputStream bout = new ByteArrayOutputStream();
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110 | byte[] buff = new byte[256];
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111 | while (max == null || max > 0) {
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112 | int n = in.read(buff);
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113 | if (n == -1) {
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114 | break;
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115 | }
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116 | bout.write(buff, 0, n);
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117 | if (max != null)
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118 | max -= n;
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119 | }
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120 | in.close();
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121 | return bout.toByteArray();
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122 | }
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123 |
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124 | private static boolean isMagicPresent(byte[] link) {
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125 | final int magic = 0x0000004C;
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126 | final int magic_offset = 0x00;
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127 | return link.length >= 32 && bytesToDword(link, magic_offset) == magic;
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128 | }
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129 |
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130 | /**
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131 | * Gobbles up link data by parsing it and storing info in member fields
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132 | * @param link all the bytes from the .lnk file
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133 | * @throws ParseException if a parsing error occurs
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134 | */
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135 | private void parseLink(byte[] link) throws ParseException {
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136 | try {
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137 | if (!isMagicPresent(link))
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138 | throw new ParseException("Invalid shortcut; magic is missing", 0);
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139 |
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140 | // get the flags byte
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141 | byte flags = link[0x14];
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142 |
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143 | // get the file attributes byte
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144 | final int file_atts_offset = 0x18;
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145 | byte file_atts = link[file_atts_offset];
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146 | byte is_dir_mask = (byte) 0x10;
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147 | if ((file_atts & is_dir_mask) > 0) {
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148 | isDirectory = true;
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149 | } else {
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150 | isDirectory = false;
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151 | }
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152 |
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153 | // if the shell settings are present, skip them
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154 | final int shell_offset = 0x4c;
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155 | final byte has_shell_mask = (byte) 0x01;
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156 | int shell_len = 0;
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157 | if ((flags & has_shell_mask) > 0) {
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158 | // the plus 2 accounts for the length marker itself
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159 | shell_len = bytesToWord(link, shell_offset) + 2;
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160 | }
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161 |
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162 | // get to the file settings
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163 | int file_start = 0x4c + shell_len;
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164 |
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165 | final int file_location_info_flag_offset_offset = 0x08;
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166 | int file_location_info_flag = link[file_start + file_location_info_flag_offset_offset];
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167 | isLocal = (file_location_info_flag & 2) == 0;
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168 | // get the local volume and local system values
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169 | //final int localVolumeTable_offset_offset = 0x0C;
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170 | final int basename_offset_offset = 0x10;
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171 | final int networkVolumeTable_offset_offset = 0x14;
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172 | final int finalname_offset_offset = 0x18;
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173 | int finalname_offset = link[file_start + finalname_offset_offset] + file_start;
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174 | String finalname = getNullDelimitedString(link, finalname_offset);
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175 | if (isLocal) {
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176 | int basename_offset = link[file_start + basename_offset_offset] + file_start;
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177 | String basename = getNullDelimitedString(link, basename_offset);
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178 | realFile = basename + finalname;
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179 | } else {
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180 | int networkVolumeTable_offset = link[file_start + networkVolumeTable_offset_offset] + file_start;
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181 | int shareName_offset_offset = 0x08;
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182 | int shareName_offset = link[networkVolumeTable_offset + shareName_offset_offset]
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183 | + networkVolumeTable_offset;
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184 | String shareName = getNullDelimitedString(link, shareName_offset);
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185 | realFile = shareName + "\\" + finalname;
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186 | }
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187 | } catch (ArrayIndexOutOfBoundsException e) {
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188 | ParseException ex = new ParseException("Could not be parsed, probably not a valid WindowsShortcut", 0);
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189 | ex.initCause(e);
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190 | throw ex;
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191 | }
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192 | }
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193 |
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194 | private static String getNullDelimitedString(byte[] bytes, int off) {
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195 | int len = 0;
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196 | // count bytes until the null character (0)
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197 | while (true) {
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198 | if (bytes[off + len] == 0) {
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199 | break;
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200 | }
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201 | len++;
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202 | }
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203 | return new String(bytes, off, len);
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204 | }
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205 |
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206 | /*
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207 | * convert two bytes into a short note, this is little endian because it's for an Intel only OS.
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208 | */
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209 | private static int bytesToWord(byte[] bytes, int off) {
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210 | return ((bytes[off + 1] & 0xff) << 8) | (bytes[off] & 0xff);
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211 | }
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212 |
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213 | private static int bytesToDword(byte[] bytes, int off) {
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214 | return (bytesToWord(bytes, off + 2) << 16) | bytesToWord(bytes, off);
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215 | }
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216 | }
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