includes/FileStore.php

   1 <?php
   2
   3 /**
   4  * @todo document (needs one-sentence top-level class description).
   5  */
   6 class FileStore {
   7         const DELETE_ORIGINAL = 1;
   8
   9         /**
  10          * Fetch the FileStore object for a given storage group
  11          */
  12         static function get( $group ) {
  13                 global $wgFileStore;
  14
  15                 if( isset( $wgFileStore[$group] ) ) {
  16                         $info = $wgFileStore[$group];
  17                         return new FileStore( $group,
  18                                 $info['directory'],
  19                                 $info['url'],
  20                                 intval( $info['hash'] ) );
  21                 } else {
  22                         return null;
  23                 }
  24         }
  25
  26         private function __construct( $group, $directory, $path, $hash ) {
  27                 $this->mGroup = $group;
  28                 $this->mDirectory = $directory;
  29                 $this->mPath = $path;
  30                 $this->mHashLevel = $hash;
  31         }
  32
  33         /**
  34          * Acquire a lock; use when performing write operations on a store.
  35          * This is attached to your master database connection, so if you
  36          * suffer an uncaught error the lock will be released when the
  37          * connection is closed.
  38          *
  39          * @todo Probably only works on MySQL. Abstract to the Database class?
  40          */
  41         static function lock() {
  42                 global $wgDBtype;
  43                 if ($wgDBtype != 'mysql')
  44                         return true;
  45                 $dbw = wfGetDB( DB_MASTER );
  46                 $lockname = $dbw->addQuotes( FileStore::lockName() );
  47                 $result = $dbw->query( "SELECT GET_LOCK($lockname, 5) AS lockstatus", __METHOD__ );
  48                 $row = $dbw->fetchObject( $result );
  49                 $dbw->freeResult( $result );
  50
  51                 if( $row->lockstatus == 1 ) {
  52                         return true;
  53                 } else {
  54                         wfDebug( __METHOD__." failed to acquire lock\n" );
  55                         return false;
  56                 }
  57         }
  58
  59         /**
  60          * Release the global file store lock.
  61          */
  62         static function unlock() {
  63                 global $wgDBtype;
  64                 if ($wgDBtype != 'mysql')
  65                         return true;
  66                 $dbw = wfGetDB( DB_MASTER );
  67                 $lockname = $dbw->addQuotes( FileStore::lockName() );
  68                 $result = $dbw->query( "SELECT RELEASE_LOCK($lockname)", __METHOD__ );
  69                 $dbw->fetchObject( $result );
  70                 $dbw->freeResult( $result );
  71         }
  72
  73         private static function lockName() {
  74                 return 'MediaWiki.' . wfWikiID() . '.FileStore';
  75         }
  76
  77         /**
  78          * Copy a file into the file store from elsewhere in the filesystem.
  79          * Should be protected by FileStore::lock() to avoid race conditions.
  80          *
  81          * @param $key storage key string
  82          * @param $flags
  83          *  DELETE_ORIGINAL - remove the source file on transaction commit.
  84          *
  85          * @throws FSException if copy can't be completed
  86          * @return FSTransaction
  87          */
  88         function insert( $key, $sourcePath, $flags=0 ) {
  89                 $destPath = $this->filePath( $key );
  90                 return $this->copyFile( $sourcePath, $destPath, $flags );
  91         }
  92
  93         /**
  94          * Copy a file from the file store to elsewhere in the filesystem.
  95          * Should be protected by FileStore::lock() to avoid race conditions.
  96          *
  97          * @param $key storage key string
  98          * @param $flags
  99          *  DELETE_ORIGINAL - remove the source file on transaction commit.
 100          *
 101          * @throws FSException if copy can't be completed
 102          * @return FSTransaction on success
 103          */
 104         function export( $key, $destPath, $flags=0 ) {
 105                 $sourcePath = $this->filePath( $key );
 106                 return $this->copyFile( $sourcePath, $destPath, $flags );
 107         }
 108
 109         private function copyFile( $sourcePath, $destPath, $flags=0 ) {
 110                 if( !file_exists( $sourcePath ) ) {
 111                         // Abort! Abort!
 112                         throw new FSException( "missing source file '$sourcePath'" );
 113                 }
 114
 115                 $transaction = new FSTransaction();
 116
 117                 if( $flags & self::DELETE_ORIGINAL ) {
 118                         $transaction->addCommit( FSTransaction::DELETE_FILE, $sourcePath );
 119                 }
 120
 121                 if( file_exists( $destPath ) ) {
 122                         // An identical file is already present; no need to copy.
 123                 } else {
 124                         if( !file_exists( dirname( $destPath ) ) ) {
 125                                 wfSuppressWarnings();
 126                                 $ok = mkdir( dirname( $destPath ), 0777, true );
 127                                 wfRestoreWarnings();
 128
 129                                 if( !$ok ) {
 130                                         throw new FSException(
 131                                                 "failed to create directory for '$destPath'" );
 132                                 }
 133                         }
 134
 135                         wfSuppressWarnings();
 136                         $ok = copy( $sourcePath, $destPath );
 137                         wfRestoreWarnings();
 138
 139                         if( $ok ) {
 140                                 wfDebug( __METHOD__." copied '$sourcePath' to '$destPath'\n" );
 141                                 $transaction->addRollback( FSTransaction::DELETE_FILE, $destPath );
 142                         } else {
 143                                 throw new FSException(
 144                                         __METHOD__." failed to copy '$sourcePath' to '$destPath'" );
 145                         }
 146                 }
 147
 148                 return $transaction;
 149         }
 150
 151         /**
 152          * Delete a file from the file store.
 153          * Caller's responsibility to make sure it's not being used by another row.
 154          *
 155          * File is not actually removed until transaction commit.
 156          * Should be protected by FileStore::lock() to avoid race conditions.
 157          *
 158          * @param $key storage key string
 159          * @throws FSException if file can't be deleted
 160          * @return FSTransaction
 161          */
 162         function delete( $key ) {
 163                 $destPath = $this->filePath( $key );
 164                 if( false === $destPath ) {
 165                         throw new FSExcepton( "file store does not contain file '$key'" );
 166                 } else {
 167                         return FileStore::deleteFile( $destPath );
 168                 }
 169         }
 170
 171         /**
 172          * Delete a non-managed file on a transactional basis.
 173          *
 174          * File is not actually removed until transaction commit.
 175          * Should be protected by FileStore::lock() to avoid race conditions.
 176          *
 177          * @param $path file to remove
 178          * @throws FSException if file can't be deleted
 179          * @return FSTransaction
 180          *
 181          * @todo Might be worth preliminary permissions check
 182          */
 183         static function deleteFile( $path ) {
 184                 if( file_exists( $path ) ) {
 185                         $transaction = new FSTransaction();
 186                         $transaction->addCommit( FSTransaction::DELETE_FILE, $path );
 187                         return $transaction;
 188                 } else {
 189                         throw new FSException( "cannot delete missing file '$path'" );
 190                 }
 191         }
 192
 193         /**
 194          * Stream a contained file directly to HTTP output.
 195          * Will throw a 404 if file is missing; 400 if invalid key.
 196          * @return true on success, false on failure
 197          */
 198         function stream( $key ) {
 199                 $path = $this->filePath( $key );
 200                 if( $path === false ) {
 201                         wfHttpError( 400, "Bad request", "Invalid or badly-formed filename." );
 202                         return false;
 203                 }
 204
 205                 if( file_exists( $path ) ) {
 206                         // Set the filename for more convenient save behavior from browsers
 207                         // FIXME: Is this safe?
 208                         header( 'Content-Disposition: inline; filename="' . $key . '"' );
 209
 210                         require_once 'StreamFile.php';
 211                         wfStreamFile( $path );
 212                 } else {
 213                         return wfHttpError( 404, "Not found",
 214                                 "The requested resource does not exist." );
 215                 }
 216         }
 217
 218         /**
 219          * Confirm that the given file key is valid.
 220          * Note that a valid key may refer to a file that does not exist.
 221          *
 222          * Key should consist of a 32-digit base-36 SHA-1 hash and
 223          * an optional alphanumeric extension, all lowercase.
 224          * The whole must not exceed 64 characters.
 225          *
 226          * @param $key
 227          * @return boolean
 228          */
 229         static function validKey( $key ) {
 230                 return preg_match( '/^[0-9a-z]{32}(\.[0-9a-z]{1,31})?$/', $key );
 231         }
 232
 233
 234         /**
 235          * Calculate file storage key from a file on disk.
 236          * You must pass an extension to it, as some files may be calculated
 237          * out of a temporary file etc.
 238          *
 239          * @param $path to file
 240          * @param $extension
 241          * @return string or false if could not open file or bad extension
 242          */
 243         static function calculateKey( $path, $extension ) {
 244                 wfSuppressWarnings();
 245                 $hash = sha1_file( $path );
 246                 wfRestoreWarnings();
 247                 if( $hash === false ) {
 248                         wfDebug( __METHOD__.": couldn't hash file '$path'\n" );
 249                         return false;
 250                 }
 251
 252                 $base36 = wfBaseConvert( $hash, 16, 36, 32 );
 253                 if( $extension == '' ) {
 254                         $key = $base36;
 255                 } else {
 256                         $key = $base36 . '.' . $extension;
 257                 }
 258
 259                 // Sanity check
 260                 if( self::validKey( $key ) ) {
 261                         return $key;
 262                 } else {
 263                         wfDebug( __METHOD__.": generated bad key '$key'\n" );
 264                         return false;
 265                 }
 266         }
 267
 268         /**
 269          * Return filesystem path to the given file.
 270          * Note that the file may or may not exist.
 271          * @return string or false if an invalid key
 272          */
 273         function filePath( $key ) {
 274                 if( self::validKey( $key ) ) {
 275                         return $this->mDirectory . DIRECTORY_SEPARATOR .
 276                                 $this->hashPath( $key, DIRECTORY_SEPARATOR );
 277                 } else {
 278                         return false;
 279                 }
 280         }
 281
 282         /**
 283          * Return URL path to the given file, if the store is public.
 284          * @return string or false if not public
 285          */
 286         function urlPath( $key ) {
 287                 if( $this->mUrl && self::validKey( $key ) ) {
 288                         return $this->mUrl . '/' . $this->hashPath( $key, '/' );
 289                 } else {
 290                         return false;
 291                 }
 292         }
 293
 294         private function hashPath( $key, $separator ) {
 295                 $parts = array();
 296                 for( $i = 0; $i < $this->mHashLevel; $i++ ) {
 297                         $parts[] = $key{$i};
 298                 }
 299                 $parts[] = $key;
 300                 return implode( $separator, $parts );
 301         }
 302 }
 303
 304 /**
 305  * Wrapper for file store transaction stuff.
 306  *
 307  * FileStore methods may return one of these for undoable operations;
 308  * you can then call its rollback() or commit() methods to perform
 309  * final cleanup if dependent database work fails or succeeds.
 310  */
 311 class FSTransaction {
 312         const DELETE_FILE = 1;
 313
 314         /**
 315          * Combine more items into a fancier transaction
 316          */
 317         function add( FSTransaction $transaction ) {
 318                 $this->mOnCommit = array_merge(
 319                         $this->mOnCommit, $transaction->mOnCommit );
 320                 $this->mOnRollback = array_merge(
 321                         $this->mOnRollback, $transaction->mOnRollback );
 322         }
 323
 324         /**
 325          * Perform final actions for success.
 326          * @return true if actions applied ok, false if errors
 327          */
 328         function commit() {
 329                 return $this->apply( $this->mOnCommit );
 330         }
 331
 332         /**
 333          * Perform final actions for failure.
 334          * @return true if actions applied ok, false if errors
 335          */
 336         function rollback() {
 337                 return $this->apply( $this->mOnRollback );
 338         }
 339
 340         // --- Private and friend functions below...
 341
 342         function __construct() {
 343                 $this->mOnCommit = array();
 344                 $this->mOnRollback = array();
 345         }
 346
 347         function addCommit( $action, $path ) {
 348                 $this->mOnCommit[] = array( $action, $path );
 349         }
 350
 351         function addRollback( $action, $path ) {
 352                 $this->mOnRollback[] = array( $action, $path );
 353         }
 354
 355         private function apply( $actions ) {
 356                 $result = true;
 357                 foreach( $actions as $item ) {
 358                         list( $action, $path ) = $item;
 359                         if( $action == self::DELETE_FILE ) {
 360                                 wfSuppressWarnings();
 361                                 $ok = unlink( $path );
 362                                 wfRestoreWarnings();
 363                                 if( $ok )
 364                                         wfDebug( __METHOD__.": deleting file '$path'\n" );
 365                                 else
 366                                         wfDebug( __METHOD__.": failed to delete file '$path'\n" );
 367                                 $result = $result && $ok;
 368                         }
 369                 }
 370                 return $result;
 371         }
 372 }
 373
 374 /**
 375  * @addtogroup Exception
 376  */
 377 class FSException extends MWException { }
 378
 379