1 package org.stackoverflowusers.file;
3 import java.io.ByteArrayOutputStream;
5 import java.io.FileInputStream;
6 import java.io.IOException;
7 import java.io.InputStream;
8 import java.text.ParseException;
11 * Represents a Windows shortcut (typically visible to Java only as a '.lnk' file).
13 * Retrieved 2011-09-23 from http://stackoverflow.com/questions/309495/windows-shortcut-lnk-parser-in-java/672775#672775
14 * Originally called LnkParser
16 * Written by: (the stack overflow users, obviously!)
17 * Apache Commons VFS dependency removed by crysxd (why were we using that!?) https://github.com/crysxd
18 * Headerified, refactored and commented by Code Bling http://stackoverflow.com/users/675721/code-bling
19 * Network file support added by Stefan Cordes http://stackoverflow.com/users/81330/stefan-cordes
20 * Adapted by Sam Brightman http://stackoverflow.com/users/2492/sam-brightman
21 * Based on information in 'The Windows Shortcut File Format' by Jesse Hager <jessehager@iname.com>
22 * And somewhat based on code from the book 'Swing Hacks: Tips and Tools for Killer GUIs'
23 * by Joshua Marinacci and Chris Adamson
25 * http://www.oreilly.com/catalog/swinghks/
27 public class WindowsShortcut
29 private boolean isDirectory;
30 private boolean isLocal;
31 private String real_file;
34 * Provides a quick test to see if this could be a valid link !
35 * If you try to instantiate a new WindowShortcut and the link is not valid,
36 * Exceptions may be thrown and Exceptions are extremely slow to generate,
37 * therefore any code needing to loop through several files should first check this.
39 * @param file the potential link
40 * @return true if may be a link, false otherwise
41 * @throws IOException if an IOException is thrown while reading from the file
43 public static boolean isPotentialValidLink(File file) throws IOException {
44 final int minimum_length = 0x64;
45 InputStream fis = new FileInputStream(file);
46 boolean isPotentiallyValid = false;
48 isPotentiallyValid = file.isFile()
49 && file.getName().toLowerCase().endsWith(".lnk")
50 && fis.available() >= minimum_length
51 && isMagicPresent(getBytes(fis, 32));
55 return isPotentiallyValid;
58 public WindowsShortcut(File file) throws IOException, ParseException {
59 InputStream in = new FileInputStream(file);
61 parseLink(getBytes(in));
68 * @return the name of the filesystem object pointed to by this shortcut
70 public String getRealFilename() {
75 * Tests if the shortcut points to a local resource.
76 * @return true if the 'local' bit is set in this shortcut, false otherwise
78 public boolean isLocal() {
83 * Tests if the shortcut points to a directory.
84 * @return true if the 'directory' bit is set in this shortcut, false otherwise
86 public boolean isDirectory() {
91 * Gets all the bytes from an InputStream
92 * @param in the InputStream from which to read bytes
93 * @return array of all the bytes contained in 'in'
94 * @throws IOException if an IOException is encountered while reading the data from the InputStream
96 private static byte[] getBytes(InputStream in) throws IOException {
97 return getBytes(in, null);
101 * Gets up to max bytes from an InputStream
102 * @param in the InputStream from which to read bytes
103 * @param max maximum number of bytes to read
104 * @return array of all the bytes contained in 'in'
105 * @throws IOException if an IOException is encountered while reading the data from the InputStream
107 private static byte[] getBytes(InputStream in, Integer max) throws IOException {
108 // read the entire file into a byte buffer
109 ByteArrayOutputStream bout = new ByteArrayOutputStream();
110 byte[] buff = new byte[256];
111 while (max == null || max > 0) {
112 int n = in.read(buff);
116 bout.write(buff, 0, n);
121 return bout.toByteArray();
124 private static boolean isMagicPresent(byte[] link) {
125 final int magic = 0x0000004C;
126 final int magic_offset = 0x00;
127 return link.length >= 32 && bytesToDword(link, magic_offset) == magic;
131 * Gobbles up link data by parsing it and storing info in member fields
132 * @param link all the bytes from the .lnk file
134 private void parseLink(byte[] link) throws ParseException {
136 if (!isMagicPresent(link))
137 throw new ParseException("Invalid shortcut; magic is missing", 0);
139 // get the flags byte
140 byte flags = link[0x14];
142 // get the file attributes byte
143 final int file_atts_offset = 0x18;
144 byte file_atts = link[file_atts_offset];
145 byte is_dir_mask = (byte)0x10;
146 if ((file_atts & is_dir_mask) > 0) {
152 // if the shell settings are present, skip them
153 final int shell_offset = 0x4c;
154 final byte has_shell_mask = (byte)0x01;
156 if ((flags & has_shell_mask) > 0) {
157 // the plus 2 accounts for the length marker itself
158 shell_len = bytesToWord(link, shell_offset) + 2;
161 // get to the file settings
162 int file_start = 0x4c + shell_len;
164 final int file_location_info_flag_offset_offset = 0x08;
165 int file_location_info_flag = link[file_start + file_location_info_flag_offset_offset];
166 isLocal = (file_location_info_flag & 2) == 0;
167 // get the local volume and local system values
168 //final int localVolumeTable_offset_offset = 0x0C;
169 final int basename_offset_offset = 0x10;
170 final int networkVolumeTable_offset_offset = 0x14;
171 final int finalname_offset_offset = 0x18;
172 int finalname_offset = link[file_start + finalname_offset_offset] + file_start;
173 String finalname = getNullDelimitedString(link, finalname_offset);
175 int basename_offset = link[file_start + basename_offset_offset] + file_start;
176 String basename = getNullDelimitedString(link, basename_offset);
177 real_file = basename + finalname;
179 int networkVolumeTable_offset = link[file_start + networkVolumeTable_offset_offset] + file_start;
180 int shareName_offset_offset = 0x08;
181 int shareName_offset = link[networkVolumeTable_offset + shareName_offset_offset]
182 + networkVolumeTable_offset;
183 String shareName = getNullDelimitedString(link, shareName_offset);
184 real_file = shareName + "\\" + finalname;
186 } catch (ArrayIndexOutOfBoundsException e) {
187 throw new ParseException("Could not be parsed, probably not a valid WindowsShortcut", 0);
191 private static String getNullDelimitedString(byte[] bytes, int off) {
193 // count bytes until the null character (0)
195 if (bytes[off + len] == 0) {
200 return new String(bytes, off, len);
204 * convert two bytes into a short note, this is little endian because it's
205 * for an Intel only OS.
207 private static int bytesToWord(byte[] bytes, int off) {
208 return ((bytes[off + 1] & 0xff) << 8) | (bytes[off] & 0xff);
211 private static int bytesToDword(byte[] bytes, int off) {
212 return (bytesToWord(bytes, off + 2) << 16) | bytesToWord(bytes, off);