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1   package org.apache.maven.plugin.clean;
2   
3   /*
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *   http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing,
15   * software distributed under the License is distributed on an
16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17   * KIND, either express or implied.  See the License for the
18   * specific language governing permissions and limitations
19   * under the License.
20   */
21  
22  import java.io.File;
23  import java.io.IOException;
24  
25  import org.apache.maven.plugin.logging.Log;
26  import org.codehaus.plexus.util.Os;
27  
28  /**
29   * Cleans directories.
30   * 
31   * @author Benjamin Bentmann
32   */
33  class Cleaner
34  {
35  
36      private static final boolean ON_WINDOWS = Os.isFamily( Os.FAMILY_WINDOWS );
37  
38      private final Logger logDebug;
39  
40      private final Logger logInfo;
41  
42      private final Logger logVerbose;
43  
44      private final Logger logWarn;
45  
46      /**
47       * Creates a new cleaner.
48       * 
49       * @param log The logger to use, may be <code>null</code> to disable logging.
50       * @param verbose Whether to perform verbose logging.
51       */
52      public Cleaner( final Log log, boolean verbose )
53      {
54          logDebug = ( log == null || !log.isDebugEnabled() ) ? null : new Logger()
55          {
56              public void log( CharSequence message )
57              {
58                  log.debug( message );
59              }
60          };
61  
62          logInfo = ( log == null || !log.isInfoEnabled() ) ? null : new Logger()
63          {
64              public void log( CharSequence message )
65              {
66                  log.info( message );
67              }
68          };
69  
70          logWarn = ( log == null || !log.isWarnEnabled() ) ? null : new Logger()
71          {
72              public void log( CharSequence message )
73              {
74                  log.warn( message );
75              }
76          };
77  
78          logVerbose = verbose ? logInfo : logDebug;
79      }
80  
81      /**
82       * Deletes the specified directories and its contents.
83       * 
84       * @param basedir The directory to delete, must not be <code>null</code>. Non-existing directories will be silently
85       *            ignored.
86       * @param selector The selector used to determine what contents to delete, may be <code>null</code> to delete
87       *            everything.
88       * @param followSymlinks Whether to follow symlinks.
89       * @param failOnError Whether to abort with an exception in case a selected file/directory could not be deleted.
90       * @param retryOnError Whether to undertake additional delete attempts in case the first attempt failed.
91       * @throws IOException If a file/directory could not be deleted and <code>failOnError</code> is <code>true</code>.
92       */
93      public void delete( File basedir, Selector selector, boolean followSymlinks, boolean failOnError,
94                          boolean retryOnError )
95          throws IOException
96      {
97          if ( !basedir.isDirectory() )
98          {
99              if ( !basedir.exists() )
100             {
101                 if ( logDebug != null )
102                 {
103                     logDebug.log( "Skipping non-existing directory " + basedir );
104                 }
105                 return;
106             }
107             throw new IOException( "Invalid base directory " + basedir );
108         }
109 
110         if ( logInfo != null )
111         {
112             logInfo.log( "Deleting " + basedir + ( selector != null ? " (" + selector + ")" : "" ) );
113         }
114 
115         File file = followSymlinks ? basedir : basedir.getCanonicalFile();
116 
117         delete( file, "", selector, followSymlinks, failOnError, retryOnError );
118     }
119 
120     /**
121      * Deletes the specified file or directory.
122      * 
123      * @param file The file/directory to delete, must not be <code>null</code>. If <code>followSymlinks</code> is
124      *            <code>false</code>, it is assumed that the parent file is canonical.
125      * @param pathname The relative pathname of the file, using {@link File#separatorChar}, must not be
126      *            <code>null</code>.
127      * @param selector The selector used to determine what contents to delete, may be <code>null</code> to delete
128      *            everything.
129      * @param followSymlinks Whether to follow symlinks.
130      * @param failOnError Whether to abort with an exception in case a selected file/directory could not be deleted.
131      * @param retryOnError Whether to undertake additional delete attempts in case the first attempt failed.
132      * @return The result of the cleaning, never <code>null</code>.
133      * @throws IOException If a file/directory could not be deleted and <code>failOnError</code> is <code>true</code>.
134      */
135     private Result delete( File file, String pathname, Selector selector, boolean followSymlinks, boolean failOnError,
136                            boolean retryOnError )
137         throws IOException
138     {
139         Result result = new Result();
140 
141         boolean isDirectory = file.isDirectory();
142 
143         if ( isDirectory )
144         {
145             if ( selector == null || selector.couldHoldSelected( pathname ) )
146             {
147                 File canonical = followSymlinks ? file : file.getCanonicalFile();
148                 if ( followSymlinks || file.equals( canonical ) )
149                 {
150                     String[] filenames = canonical.list();
151                     if ( filenames != null )
152                     {
153                         String prefix = ( pathname.length() > 0 ) ? pathname + File.separatorChar : "";
154                         for ( int i = filenames.length - 1; i >= 0; i-- )
155                         {
156                             String filename = filenames[i];
157                             File child = new File( canonical, filename );
158                             result.update( delete( child, prefix + filename, selector, followSymlinks, failOnError,
159                                                    retryOnError ) );
160                         }
161                     }
162                 }
163                 else if ( logDebug != null )
164                 {
165                     logDebug.log( "Not recursing into symlink " + file );
166                 }
167             }
168             else if ( logDebug != null )
169             {
170                 logDebug.log( "Not recursing into directory without included files " + file );
171             }
172         }
173 
174         if ( !result.excluded && ( selector == null || selector.isSelected( pathname ) ) )
175         {
176             if ( logVerbose != null )
177             {
178                 if ( isDirectory )
179                 {
180                     logVerbose.log( "Deleting directory " + file );
181                 }
182                 else if ( file.exists() )
183                 {
184                     logVerbose.log( "Deleting file " + file );
185                 }
186                 else
187                 {
188                     logVerbose.log( "Deleting dangling symlink " + file );
189                 }
190             }
191             result.failures += delete( file, failOnError, retryOnError );
192         }
193         else
194         {
195             result.excluded = true;
196         }
197 
198         return result;
199     }
200 
201     /**
202      * Deletes the specified file, directory. If the path denotes a symlink, only the link is removed, its target is
203      * left untouched.
204      * 
205      * @param file The file/directory to delete, must not be <code>null</code>.
206      * @param failOnError Whether to abort with an exception in case the file/directory could not be deleted.
207      * @param retryOnError Whether to undertake additional delete attempts in case the first attempt failed.
208      * @return <code>0</code> if the file was deleted, <code>1</code> otherwise.
209      * @throws IOException If a file/directory could not be deleted and <code>failOnError</code> is <code>true</code>.
210      */
211     private int delete( File file, boolean failOnError, boolean retryOnError )
212         throws IOException
213     {
214         if ( !file.delete() )
215         {
216             boolean deleted = false;
217 
218             if ( retryOnError )
219             {
220                 if ( ON_WINDOWS )
221                 {
222                     // try to release any locks held by non-closed files
223                     System.gc();
224                 }
225 
226                 int[] delays = { 50, 250, 750 };
227                 for ( int i = 0; !deleted && i < delays.length; i++ )
228                 {
229                     try
230                     {
231                         Thread.sleep( delays[i] );
232                     }
233                     catch ( InterruptedException e )
234                     {
235                         // ignore
236                     }
237                     deleted = file.delete() || !file.exists();
238                 }
239             }
240             else
241             {
242                 deleted = !file.exists();
243             }
244 
245             if ( !deleted )
246             {
247                 if ( failOnError )
248                 {
249                     throw new IOException( "Failed to delete " + file );
250                 }
251                 else
252                 {
253                     if ( logWarn != null )
254                     {
255                         logWarn.log( "Failed to delete " + file );
256                     }
257                     return 1;
258                 }
259             }
260         }
261 
262         return 0;
263     }
264 
265     private static class Result
266     {
267 
268         public int failures;
269 
270         public boolean excluded;
271 
272         public void update( Result result )
273         {
274             failures += result.failures;
275             excluded |= result.excluded;
276         }
277 
278     }
279 
280     private static interface Logger
281     {
282 
283         public void log( CharSequence message );
284 
285     }
286 
287 }