| 1 | /* |
| 2 | |
| 3 | Derby - Class org.apache.derby.impl.io.DirFile |
| 4 | |
| 5 | Copyright 2004 The Apache Software Foundation or its licensors, as applicable. |
| 6 | |
| 7 | Licensed under the Apache License, Version 2.0 (the "License"); |
| 8 | you may not use this file except in compliance with the License. |
| 9 | You may obtain a copy of the License at |
| 10 | |
| 11 | http://www.apache.org/licenses/LICENSE-2.0 |
| 12 | |
| 13 | Unless required by applicable law or agreed to in writing, software |
| 14 | distributed under the License is distributed on an "AS IS" BASIS, |
| 15 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 16 | See the License for the specific language governing permissions and |
| 17 | limitations under the License. |
| 18 | |
| 19 | */ |
| 20 | |
| 21 | package org.apache.derby.impl.io; |
| 22 | |
| 23 | import org.apache.derby.io.StorageFile; |
| 24 | import org.apache.derby.io.StorageRandomAccessFile; |
| 25 | |
| 26 | import org.apache.derby.iapi.services.sanity.SanityManager; |
| 27 | |
| 28 | import java.io.File; |
| 29 | import java.io.InputStream; |
| 30 | import java.io.OutputStream; |
| 31 | import java.io.FileOutputStream; |
| 32 | import java.io.FileInputStream; |
| 33 | import java.io.IOException; |
| 34 | import java.io.FileNotFoundException; |
| 35 | import java.io.RandomAccessFile; |
| 36 | import java.net.MalformedURLException; |
| 37 | import java.net.URL; |
| 38 | |
| 39 | /** |
| 40 | * This class provides a disk based implementation of the StorageFile interface. It is used by the |
| 41 | * database engine to access persistent data and transaction logs under the directory (default) subsubprotocol. |
| 42 | */ |
| 43 | class DirFile extends File implements StorageFile |
| 44 | { |
| 45 | |
| 46 | /** |
| 47 | * Construct a DirFile from a path name. |
| 48 | * |
| 49 | * @param path The path name. |
| 50 | */ |
| 51 | DirFile( String path) |
| 52 | { |
| 53 | super( path); |
| 54 | } |
| 55 | |
| 56 | /** |
| 57 | * Construct a DirFile from a directory name and a file name. |
| 58 | * |
| 59 | * @param directoryName The directory part of the path name. |
| 60 | * @param fileName The name of the file within the directory. |
| 61 | */ |
| 62 | DirFile( String directoryName, String fileName) |
| 63 | { |
| 64 | super( directoryName, fileName); |
| 65 | } |
| 66 | |
| 67 | /** |
| 68 | * Construct a DirFile from a directory name and a file name. |
| 69 | * |
| 70 | * @param directoryName The directory part of the path name. |
| 71 | * @param fileName The name of the file within the directory. |
| 72 | */ |
| 73 | DirFile( DirFile directoryName, String fileName) |
| 74 | { |
| 75 | super( (File) directoryName, fileName); |
| 76 | } |
| 77 | |
| 78 | /** |
| 79 | * Get the name of the parent directory if this name includes a parent. |
| 80 | * |
| 81 | * @return An StorageFile denoting the parent directory of this StorageFile, if it has a parent, null if |
| 82 | * it does not have a parent. |
| 83 | */ |
| 84 | public StorageFile getParentDir() |
| 85 | { |
| 86 | String parent = getParent(); |
| 87 | if( parent == null) |
| 88 | return null; |
| 89 | return new DirFile( parent); |
| 90 | } |
| 91 | |
| 92 | /** |
| 93 | * Get the name of the directory of temporary files. |
| 94 | * |
| 95 | * @return The abstract name of the temp directory; |
| 96 | */ |
| 97 | static StorageFile getTempDir() throws IOException |
| 98 | { |
| 99 | File temp = File.createTempFile("derby", "tmp"); |
| 100 | StorageFile parent = new DirFile( temp.getParent()); |
| 101 | temp.delete(); |
| 102 | |
| 103 | return parent; |
| 104 | } // End of getTempDir |
| 105 | |
| 106 | /** |
| 107 | * Creates an output stream from a file name. |
| 108 | * |
| 109 | * @return an output stream suitable for writing to the file. |
| 110 | * |
| 111 | * @exception FileNotFoundException if the file exists but is a directory |
| 112 | * rather than a regular file, does not exist but cannot be created, or |
| 113 | * cannot be opened for any other reason. |
| 114 | */ |
| 115 | public OutputStream getOutputStream( ) throws FileNotFoundException |
| 116 | { |
| 117 | return new FileOutputStream( (File) this); |
| 118 | } |
| 119 | |
| 120 | /** |
| 121 | * Creates an output stream from a file name. |
| 122 | * |
| 123 | * @param append If true then data will be appended to the end of the file, if it already exists. |
| 124 | * If false and a normal file already exists with this name the file will first be truncated |
| 125 | * to zero length. |
| 126 | * |
| 127 | * @return an output stream suitable for writing to the file. |
| 128 | * |
| 129 | * @exception FileNotFoundException if the file exists but is a directory |
| 130 | * rather than a regular file, does not exist but cannot be created, or |
| 131 | * cannot be opened for any other reason. |
| 132 | */ |
| 133 | public OutputStream getOutputStream( final boolean append) throws FileNotFoundException |
| 134 | { |
| 135 | return new FileOutputStream( getPath(), append); |
| 136 | } |
| 137 | |
| 138 | /** |
| 139 | * Creates an input stream from a file name. |
| 140 | * |
| 141 | * @return an input stream suitable for reading from the file. |
| 142 | * |
| 143 | * @exception FileNotFoundException if the file is not found. |
| 144 | */ |
| 145 | public InputStream getInputStream( ) throws FileNotFoundException |
| 146 | { |
| 147 | return new FileInputStream( (File) this); |
| 148 | } |
| 149 | |
| 150 | /** |
| 151 | * Get an exclusive lock. This is used to ensure that two or more JVMs do not open the same database |
| 152 | * at the same time. |
| 153 | * |
| 154 | * |
| 155 | * @return EXCLUSIVE_FILE_LOCK_NOT_AVAILABLE if the lock cannot be acquired because it is already held.<br> |
| 156 | * EXCLUSIVE_FILE_LOCK if the lock was successfully acquired.<br> |
| 157 | * NO_FILE_LOCK_SUPPORT if the system does not support exclusive locks.<br> |
| 158 | */ |
| 159 | public synchronized int getExclusiveFileLock() |
| 160 | { |
| 161 | if (exists()) |
| 162 | { |
| 163 | delete(); |
| 164 | } |
| 165 | try |
| 166 | { |
| 167 | //Just create an empty file |
| 168 | RandomAccessFile lockFileOpen = new RandomAccessFile( (File) this, "rw"); |
| 169 | lockFileOpen.getFD().sync( ); |
| 170 | lockFileOpen.close(); |
| 171 | }catch(IOException ioe) |
| 172 | { |
| 173 | // do nothing - it may be read only medium, who knows what the |
| 174 | // problem is |
| 175 | if (SanityManager.DEBUG) |
| 176 | { |
| 177 | SanityManager.THROWASSERT("Unable to create Exclusive Lock File " + getPath()); |
| 178 | } |
| 179 | } |
| 180 | |
| 181 | return NO_FILE_LOCK_SUPPORT; |
| 182 | } // end of getExclusiveFileLock |
| 183 | |
| 184 | /** |
| 185 | * Release the resource associated with an earlier acquired exclusive lock |
| 186 | * |
| 187 | * @see #getExclusiveFileLock |
| 188 | */ |
| 189 | public synchronized void releaseExclusiveFileLock() |
| 190 | { |
| 191 | if( exists()) |
| 192 | { |
| 193 | delete(); |
| 194 | } |
| 195 | } // End of releaseExclusiveFileLock |
| 196 | |
| 197 | /** |
| 198 | * Get a random access (read/write) file. |
| 199 | * |
| 200 | * @param mode "r", "rw", "rws", or "rwd". The "rws" and "rwd" modes specify |
| 201 | * that the data is to be written to persistent store, consistent with the |
| 202 | * java.io.RandomAccessFile class ("synchronized" with the persistent |
| 203 | * storage, in the file system meaning of the word "synchronized"). However |
| 204 | * the implementation is not required to implement the "rws" or "rwd" |
| 205 | * modes. The implementation may treat "rws" and "rwd" as "rw". It is up to |
| 206 | * the user of this interface to call the StorageRandomAccessFile.sync |
| 207 | * method. If the "rws" or "rwd" modes are supported and the |
| 208 | * RandomAccessFile was opened in "rws" or "rwd" mode then the |
| 209 | * implementation of StorageRandomAccessFile.sync need not do anything. |
| 210 | * |
| 211 | * @return an object that can be used for random access to the file. |
| 212 | * |
| 213 | * @exception IllegalArgumentException if the mode argument is not equal to one of "r", "rw". |
| 214 | * @exception FileNotFoundException if the file exists but is a directory rather than a regular |
| 215 | * file, or cannot be opened or created for any other reason . |
| 216 | */ |
| 217 | public StorageRandomAccessFile getRandomAccessFile( String mode) throws FileNotFoundException |
| 218 | { |
| 219 | // Assume that modes "rws" and "rwd" are not supported. |
| 220 | if( "rws".equals( mode) || "rwd".equals( mode)) |
| 221 | mode = "rw"; |
| 222 | return new DirRandomAccessFile( (File) this, mode); |
| 223 | } // end of getRandomAccessFile |
| 224 | |
| 225 | /** |
| 226 | * Rename the file denoted by this name. Note that StorageFile objects are immutable. This method |
| 227 | * renames the underlying file, it does not change this StorageFile object. The StorageFile object denotes the |
| 228 | * same name as before, however the exists() method will return false after the renameTo method |
| 229 | * executes successfully. |
| 230 | * |
| 231 | *<p>It is not specified whether this method will succeed if a file already exists under the new name. |
| 232 | * |
| 233 | * @param newName the new name. |
| 234 | * |
| 235 | * @return <b>true</b> if the rename succeeded, <b>false</b> if not. |
| 236 | */ |
| 237 | public boolean renameTo( StorageFile newName) |
| 238 | { |
| 239 | return super.renameTo( (File) newName); |
| 240 | } |
| 241 | |
| 242 | /** |
| 243 | * Deletes the named file and, if it is a directory, all the files and directories it contains. |
| 244 | * |
| 245 | * @return <b>true</b> if the named file or directory is successfully deleted, <b>false</b> if not |
| 246 | */ |
| 247 | public boolean deleteAll() |
| 248 | { |
| 249 | if( !exists()) |
| 250 | return false; |
| 251 | if( isDirectory()) |
| 252 | { |
| 253 | String[] childList = super.list(); |
| 254 | String parentName = getPath(); |
| 255 | for( int i = 0; i < childList.length; i++) |
| 256 | { |
| 257 | if( childList[i].equals( ".") || childList[i].equals( "..")) |
| 258 | continue; |
| 259 | DirFile child = new DirFile( parentName, childList[i]); |
| 260 | if( ! child.deleteAll()) |
| 261 | return false; |
| 262 | } |
| 263 | } |
| 264 | return delete(); |
| 265 | } // end of deleteAll |
| 266 | |
| 267 | /** |
| 268 | * @see org.apache.derby.io.StorageFile#getURL() |
| 269 | */ |
| 270 | public URL getURL() throws MalformedURLException { |
| 271 | |
| 272 | return toURL(); |
| 273 | } |
| 274 | } |