includes/ZipDirectoryReader.php

   1 <?php
   2
   3 /**
   4  * A class for reading ZIP file directories, for the purposes of upload
   5  * verification.
   6  *
   7  * Only a functional interface is provided: ZipFileReader::read(). No access is
   8  * given to object instances.
   9  *
  10  */
  11 class ZipDirectoryReader {
  12         /**
  13          * Read a ZIP file and call a function for each file discovered in it.
  14          *
  15          * Because this class is aimed at verification, an error is raised on
  16          * suspicious or ambiguous input, instead of emulating some standard
  17          * behaviour.
  18          *
  19          * @param $fileName string The archive file name
  20          * @param $callback Array The callback function. It will be called for each file
  21          *   with a single associative array each time, with members:
  22          *
  23          *      - name: The file name. Directories conventionally have a trailing
  24          *        slash.
  25          *
  26          *      - mtime: The file modification time, in MediaWiki 14-char format
  27          *
  28          *      - size: The uncompressed file size
  29          *
  30          * @param $options Array An associative array of read options, with the option
  31          *    name in the key. This may currently contain:
  32          *
  33          *      - zip64: If this is set to true, then we will emulate a
  34          *        library with ZIP64 support, like OpenJDK 7. If it is set to
  35          *        false, then we will emulate a library with no knowledge of
  36          *        ZIP64.
  37          *
  38          *        NOTE: The ZIP64 code is untested and probably doesn't work. It
  39          *        turned out to be easier to just reject ZIP64 archive uploads,
  40          *        since they are likely to be very rare. Confirming safety of a
  41          *        ZIP64 file is fairly complex. What do you do with a file that is
  42          *        ambiguous and broken when read with a non-ZIP64 reader, but valid
  43          *        when read with a ZIP64 reader? This situation is normal for a
  44          *        valid ZIP64 file, and working out what non-ZIP64 readers will make
  45          *        of such a file is not trivial.
  46          *
  47          * @return Status object. The following fatal errors are defined:
  48          *
  49          *      - zip-file-open-error: The file could not be opened.
  50          *
  51          *      - zip-wrong-format: The file does not appear to be a ZIP file.
  52          *
  53          *      - zip-bad: There was something wrong or ambiguous about the file
  54          *        data.
  55          *
  56          *      - zip-unsupported: The ZIP file uses features which
  57          *        ZipDirectoryReader does not support.
  58          *
  59          * The default messages for those fatal errors are written in a way that
  60          * makes sense for upload verification.
  61          *
  62          * If a fatal error is returned, more information about the error will be
  63          * available in the debug log.
  64          *
  65          * Note that the callback function may be called any number of times before
  66          * a fatal error is returned. If this occurs, the data sent to the callback
  67          * function should be discarded.
  68          */
  69         public static function read( $fileName, $callback, $options = array() ) {
  70                 $zdr = new self( $fileName, $callback, $options );
  71                 return $zdr->execute();
  72         }
  73
  74         /** The file name */
  75         var $fileName;
  76
  77         /** The opened file resource */
  78         var $file;
  79
  80         /** The cached length of the file, or null if it has not been loaded yet. */
  81         var $fileLength;
  82
  83         /** A segmented cache of the file contents */
  84         var $buffer;
  85
  86         /** The file data callback */
  87         var $callback;
  88
  89         /** The ZIP64 mode */
  90         var $zip64 = false;
  91
  92         /** Stored headers */
  93         var $eocdr, $eocdr64, $eocdr64Locator;
  94
  95         /** The "extra field" ID for ZIP64 central directory entries */
  96         const ZIP64_EXTRA_HEADER = 0x0001;
  97
  98         /** The segment size for the file contents cache */
  99         const SEGSIZE = 16384;
 100
 101         /** The index of the "general field" bit for UTF-8 file names */
 102         const GENERAL_UTF8 = 11;
 103
 104         /** The index of the "general field" bit for central directory encryption */
 105         const GENERAL_CD_ENCRYPTED = 13;
 106
 107
 108         /**
 109          * Private constructor
 110          */
 111         protected function __construct( $fileName, $callback, $options ) {
 112                 $this->fileName = $fileName;
 113                 $this->callback = $callback;
 114
 115                 if ( isset( $options['zip64'] ) ) {
 116                         $this->zip64 = $options['zip64'];
 117                 }
 118         }
 119
 120         /**
 121          * Read the directory according to settings in $this.
 122          *
 123          * @return Status
 124          */
 125         function execute() {
 126                 $this->file = fopen( $this->fileName, 'r' );
 127                 $this->data = array();
 128                 if ( !$this->file ) {
 129                         return Status::newFatal( 'zip-file-open-error' );
 130                 }
 131
 132                 $status = Status::newGood();
 133                 try {
 134                         $this->readEndOfCentralDirectoryRecord();
 135                         if ( $this->zip64 ) {
 136                                 list( $offset, $size ) = $this->findZip64CentralDirectory();
 137                                 $this->readCentralDirectory( $offset, $size );
 138                         } else {
 139                                 if ( $this->eocdr['CD size'] == 0xffffffff
 140                                         || $this->eocdr['CD offset'] == 0xffffffff
 141                                         || $this->eocdr['CD entries total'] == 0xffff )
 142                                 {
 143                                         $this->error( 'zip-unsupported', 'Central directory header indicates ZIP64, ' .
 144                                                 'but we are in legacy mode. Rejecting this upload is necessary to avoid '.
 145                                                 'opening vulnerabilities on clients using OpenJDK 7 or later.' );
 146                                 }
 147
 148                                 list( $offset, $size ) = $this->findOldCentralDirectory();
 149                                 $this->readCentralDirectory( $offset, $size );
 150                         }
 151                 } catch ( ZipDirectoryReaderError $e ) {
 152                         $status->fatal( $e->getErrorCode() );
 153                 }
 154
 155                 fclose( $this->file );
 156                 return $status;
 157         }
 158
 159         /**
 160          * Throw an error, and log a debug message
 161          */
 162         function error( $code, $debugMessage ) {
 163                 wfDebug( __CLASS__.": Fatal error: $debugMessage\n" );
 164                 throw new ZipDirectoryReaderError( $code );
 165         }
 166
 167         /**
 168          * Read the header which is at the end of the central directory,
 169          * unimaginatively called the "end of central directory record" by the ZIP
 170          * spec.
 171          */
 172         function readEndOfCentralDirectoryRecord() {
 173                 $info = array(
 174                         'signature' => 4,
 175                         'disk' => 2,
 176                         'CD start disk' => 2,
 177                         'CD entries this disk' => 2,
 178                         'CD entries total' => 2,
 179                         'CD size' => 4,
 180                         'CD offset' => 4,
 181                         'file comment length' => 2,
 182                 );
 183                 $structSize = $this->getStructSize( $info );
 184                 $startPos = $this->getFileLength() - 65536 - $structSize;
 185                 if ( $startPos < 0 ) {
 186                         $startPos = 0;
 187                 }
 188
 189                 $block = $this->getBlock( $startPos );
 190                 $sigPos = strrpos( $block, "PK\x05\x06" );
 191                 if ( $sigPos === false ) {
 192                         $this->error( 'zip-wrong-format',
 193                                 "zip file lacks EOCDR signature. It probably isn't a zip file." );
 194                 }
 195
 196                 $this->eocdr = $this->unpack( substr( $block, $sigPos ), $info );
 197                 $this->eocdr['EOCDR size'] = $structSize + $this->eocdr['file comment length'];
 198
 199                 if ( $structSize + $this->eocdr['file comment length'] != strlen( $block ) - $sigPos ) {
 200                         $this->error( 'zip-bad', 'trailing bytes after the end of the file comment' );
 201                 }
 202                 if (   $this->eocdr['disk'] !== 0
 203                         || $this->eocdr['CD start disk'] !== 0 )
 204                 {
 205                         $this->error( 'zip-unsupported', 'more than one disk (in EOCDR)' );
 206                 }
 207                 $this->eocdr += $this->unpack(
 208                         $block,
 209                         array( 'file comment' => array( 'string', $this->eocdr['file comment length'] ) ),
 210                         $sigPos + $structSize );
 211                 $this->eocdr['position'] = $startPos + $sigPos;
 212         }
 213
 214         /**
 215          * Read the header called the "ZIP64 end of central directory locator". An
 216          * error will be raised if it does not exist.
 217          */
 218         function readZip64EndOfCentralDirectoryLocator() {
 219                 $info = array(
 220                         'signature' => array( 'string', 4 ),
 221                         'eocdr64 start disk' => 4,
 222                         'eocdr64 offset' => 8,
 223                         'number of disks' => 4,
 224                 );
 225                 $structSize = $this->getStructSize( $info );
 226
 227                 $block = $this->getBlock( $this->getFileLength() - $this->eocdr['EOCDR size']
 228                         - $structSize, $structSize );
 229                 $this->eocdr64Locator = $data = $this->unpack( $block, $info );
 230
 231                 if ( $data['signature'] !== "PK\x06\x07" ) {
 232                         // Note: Java will allow this and continue to read the
 233                         // EOCDR64, so we have to reject the upload, we can't
 234                         // just use the EOCDR header instead.
 235                         $this->error( 'zip-bad', 'wrong signature on Zip64 end of central directory locator' );
 236                 }
 237         }
 238
 239         /**
 240          * Read the header called the "ZIP64 end of central directory record". It
 241          * may replace the regular "end of central directory record" in ZIP64 files.
 242          */
 243         function readZip64EndOfCentralDirectoryRecord() {
 244                 if (   $this->eocdr64Locator['eocdr64 start disk'] != 0
 245                         || $this->eocdr64Locator['number of disks'] != 0 )
 246                 {
 247                         $this->error( 'zip-unsupported', 'more than one disk (in EOCDR64 locator)' );
 248                 }
 249
 250                 $info = array(
 251                         'signature' => array( 'string', 4 ),
 252                         'EOCDR64 size' => 8,
 253                         'version made by' => 2,
 254                         'version needed' => 2,
 255                         'disk' => 4,
 256                         'CD start disk' => 4,
 257                         'CD entries this disk' => 8,
 258                         'CD entries total' => 8,
 259                         'CD size' => 8,
 260                         'CD offset' => 8
 261                 );
 262                 $structSize = $this->getStructSize( $info );
 263                 $block = $this->getBlock( $this->eocdr64Locator['eocdr64 offset'], $structSize );
 264                 $this->eocdr64 = $data = $this->unpack( $block, $info );
 265                 if ( $data['signature'] !== "PK\x06\x06" ) {
 266                         $this->error( 'zip-bad', 'wrong signature on Zip64 end of central directory record' );
 267                 }
 268                 if (   $data['disk'] !== 0
 269                         || $data['CD start disk'] !== 0 )
 270                 {
 271                         $this->error( 'zip-unsupported', 'more than one disk (in EOCDR64)' );
 272                 }
 273         }
 274
 275         /**
 276          * Find the location of the central directory, as would be seen by a
 277          * non-ZIP64 reader.
 278          *
 279          * @return List containing offset, size and end position.
 280          */
 281         function findOldCentralDirectory() {
 282                 $size = $this->eocdr['CD size'];
 283                 $offset = $this->eocdr['CD offset'];
 284                 $endPos = $this->eocdr['position'];
 285
 286                 // Some readers use the EOCDR position instead of the offset field
 287                 // to find the directory, so to be safe, we check if they both agree.
 288                 if ( $offset + $size != $endPos ) {
 289                         $this->error( 'zip-bad', 'the central directory does not immediately precede the end ' .
 290                                 'of central directory record' );
 291                 }
 292                 return array( $offset, $size );
 293         }
 294
 295         /**
 296          * Find the location of the central directory, as would be seen by a
 297          * ZIP64-compliant reader.
 298          *
 299          * @return List containing offset, size and end position.
 300          */
 301         function findZip64CentralDirectory() {
 302                 // The spec is ambiguous about the exact rules of precedence between the
 303                 // ZIP64 headers and the original headers. Here we follow zip_util.c
 304                 // from OpenJDK 7.
 305                 $size = $this->eocdr['CD size'];
 306                 $offset = $this->eocdr['CD offset'];
 307                 $numEntries = $this->eocdr['CD entries total'];
 308                 $endPos = $this->eocdr['position'];
 309                 if (   $size == 0xffffffff
 310                         || $offset == 0xffffffff
 311                         || $numEntries == 0xffff )
 312                 {
 313                         $this->readZip64EndOfCentralDirectoryLocator();
 314
 315                         if ( isset( $this->eocdr64Locator['eocdr64 offset'] ) ) {
 316                                 $this->readZip64EndOfCentralDirectoryRecord();
 317                                 if ( isset( $this->eocdr64['CD offset'] ) ) {
 318                                         $size = $this->eocdr64['CD size'];
 319                                         $offset = $this->eocdr64['CD offset'];
 320                                         $endPos = $this->eocdr64Locator['eocdr64 offset'];
 321                                 }
 322                         }
 323                 }
 324                 // Some readers use the EOCDR position instead of the offset field
 325                 // to find the directory, so to be safe, we check if they both agree.
 326                 if ( $offset + $size != $endPos ) {
 327                         $this->error( 'zip-bad', 'the central directory does not immediately precede the end ' .
 328                                 'of central directory record' );
 329                 }
 330                 return array( $offset, $size );
 331         }
 332
 333         /**
 334          * Read the central directory at the given location
 335          */
 336         function readCentralDirectory( $offset, $size ) {
 337                 $block = $this->getBlock( $offset, $size );
 338
 339                 $fixedInfo = array(
 340                         'signature' => array( 'string', 4 ),
 341                         'version made by' => 2,
 342                         'version needed' => 2,
 343                         'general bits' => 2,
 344                         'compression method' => 2,
 345                         'mod time' => 2,
 346                         'mod date' => 2,
 347                         'crc-32' => 4,
 348                         'compressed size' => 4,
 349                         'uncompressed size' => 4,
 350                         'name length' => 2,
 351                         'extra field length' => 2,
 352                         'comment length' => 2,
 353                         'disk number start' => 2,
 354                         'internal attrs' => 2,
 355                         'external attrs' => 4,
 356                         'local header offset' => 4,
 357                 );
 358                 $fixedSize = $this->getStructSize( $fixedInfo );
 359
 360                 $pos = 0;
 361                 while ( $pos < $size ) {
 362                         $data = $this->unpack( $block, $fixedInfo, $pos );
 363                         $pos += $fixedSize;
 364
 365                         if ( $data['signature'] !== "PK\x01\x02" ) {
 366                                 $this->error( 'zip-bad', 'Invalid signature found in directory entry' );
 367                         }
 368
 369                         $variableInfo = array(
 370                                 'name' => array( 'string', $data['name length'] ),
 371                                 'extra field' => array( 'string', $data['extra field length'] ),
 372                                 'comment' => array( 'string', $data['comment length'] ),
 373                         );
 374                         $data += $this->unpack( $block, $variableInfo, $pos );
 375                         $pos += $this->getStructSize( $variableInfo );
 376
 377                         if (   $this->zip64 && (
 378                                    $data['compressed size'] == 0xffffffff
 379                                 || $data['uncompressed size'] == 0xffffffff
 380                                 || $data['local header offset'] == 0xffffffff ) )
 381                         {
 382                                 $zip64Data = $this->unpackZip64Extra( $data['extra field'] );
 383                                 if ( $zip64Data ) {
 384                                         $data = $zip64Data + $data;
 385                                 }
 386                         }
 387
 388                         if ( $this->testBit( $data['general bits'], self::GENERAL_CD_ENCRYPTED ) ) {
 389                                 $this->error( 'zip-unsupported', 'central directory encryption is not supported' );
 390                         }
 391
 392                         // Convert the timestamp into MediaWiki format
 393                         // For the format, please see the MS-DOS 2.0 Programmer's Reference,
 394                         // pages 3-5 and 3-6.
 395                         $time = $data['mod time'];
 396                         $date = $data['mod date'];
 397
 398                         $year = 1980 + ( $date >> 9 );
 399                         $month = ( $date >> 5 ) & 15;
 400                         $day = $date & 31;
 401                         $hour = ( $time >> 11 ) & 31;
 402                         $minute = ( $time >> 5 ) & 63;
 403                         $second = ( $time & 31 ) * 2;
 404                         $timestamp = sprintf( "%04d%02d%02d%02d%02d%02d",
 405                                 $year, $month, $day, $hour, $minute, $second );
 406
 407                         // Convert the character set in the file name
 408                         if ( !function_exists( 'iconv' )
 409                                 || $this->testBit( $data['general bits'], self::GENERAL_UTF8 ) )
 410                         {
 411                                 $name = $data['name'];
 412                         } else {
 413                                 $name = iconv( 'CP437', 'UTF-8', $data['name'] );
 414                         }
 415
 416                         // Compile a data array for the user, with a sensible format
 417                         $userData = array(
 418                                 'name' => $name,
 419                                 'mtime' => $timestamp,
 420                                 'size' => $data['uncompressed size'],
 421                         );
 422                         call_user_func( $this->callback, $userData );
 423                 }
 424         }
 425
 426         /**
 427          * Interpret ZIP64 "extra field" data and return an associative array.
 428          */
 429         function unpackZip64Extra( $extraField ) {
 430                 $extraHeaderInfo = array(
 431                         'id' => 2,
 432                         'size' => 2,
 433                 );
 434                 $extraHeaderSize = $this->getStructSize( $extraHeaderInfo );
 435
 436                 $zip64ExtraInfo = array(
 437                         'uncompressed size' => 8,
 438                         'compressed size' => 8,
 439                         'local header offset' => 8,
 440                         'disk number start' => 4,
 441                 );
 442
 443                 $extraPos = 0;
 444                 while ( $extraPos < strlen( $extraField ) ) {
 445                         $extra = $this->unpack( $extraField, $extraHeaderInfo, $extraPos );
 446                         $extraPos += $extraHeaderSize;
 447                         $extra += $this->unpack( $extraField,
 448                                 array( 'data' => array( 'string', $extra['size'] ) ),
 449                                 $extraPos );
 450                         $extraPos += $extra['size'];
 451
 452                         if ( $extra['id'] == self::ZIP64_EXTRA_HEADER ) {
 453                                 return $this->unpack( $extra['data'], $zip64ExtraInfo );
 454                         }
 455                 }
 456
 457                 return false;
 458         }
 459
 460         /**
 461          * Get the length of the file.
 462          */
 463         function getFileLength() {
 464                 if ( $this->fileLength === null ) {
 465                         $stat = fstat( $this->file );
 466                         $this->fileLength = $stat['size'];
 467                 }
 468                 return $this->fileLength;
 469         }
 470
 471         /**
 472          * Get the file contents from a given offset. If there are not enough bytes
 473          * in the file to satisfy the request, an exception will be thrown.
 474          *
 475          * @param $start The byte offset of the start of the block.
 476          * @param $length The number of bytes to return. If omitted, the remainder
 477          *    of the file will be returned.
 478          *
 479          * @return string
 480          */
 481         function getBlock( $start, $length = null ) {
 482                 $fileLength = $this->getFileLength();
 483                 if ( $start >= $fileLength ) {
 484                         $this->error( 'zip-bad', "getBlock() requested position $start, " .
 485                                 "file length is $fileLength" );
 486                 }
 487                 if ( $length === null ) {
 488                         $length = $fileLength - $start;
 489                 }
 490                 $end = $start + $length;
 491                 if ( $end > $fileLength ) {
 492                         $this->error( 'zip-bad', "getBlock() requested end position $end, " .
 493                                 "file length is $fileLength" );
 494                 }
 495                 $startSeg = floor( $start / self::SEGSIZE );
 496                 $endSeg = ceil( $end / self::SEGSIZE );
 497
 498                 $block = '';
 499                 for ( $segIndex = $startSeg; $segIndex <= $endSeg; $segIndex++ ) {
 500                         $block .= $this->getSegment( $segIndex );
 501                 }
 502
 503                 $block = substr( $block,
 504                         $start - $startSeg * self::SEGSIZE,
 505                         $length );
 506
 507                 if ( strlen( $block ) < $length ) {
 508                         $this->error( 'zip-bad', 'getBlock() returned an unexpectedly small amount of data' );
 509                 }
 510
 511                 return $block;
 512         }
 513
 514         /**
 515          * Get a section of the file starting at position $segIndex * self::SEGSIZE,
 516          * of length self::SEGSIZE. The result is cached. This is a helper function
 517          * for getBlock().
 518          *
 519          * If there are not enough bytes in the file to satsify the request, the
 520          * return value will be truncated. If a request is made for a segment beyond
 521          * the end of the file, an empty string will be returned.
 522          */
 523         function getSegment( $segIndex ) {
 524                 if ( !isset( $this->buffer[$segIndex] ) ) {
 525                         $bytePos = $segIndex * self::SEGSIZE;
 526                         if ( $bytePos >= $this->getFileLength() ) {
 527                                 $this->buffer[$segIndex] = '';
 528                                 return '';
 529                         }
 530                         if ( fseek( $this->file, $bytePos ) ) {
 531                                 $this->error( 'zip-bad', "seek to $bytePos failed" );
 532                         }
 533                         $seg = fread( $this->file, self::SEGSIZE );
 534                         if ( $seg === false ) {
 535                                 $this->error( 'zip-bad', "read from $bytePos failed" );
 536                         }
 537                         $this->buffer[$segIndex] = $seg;
 538                 }
 539                 return $this->buffer[$segIndex];
 540         }
 541
 542         /**
 543          * Get the size of a structure in bytes. See unpack() for the format of $struct.
 544          */
 545         function getStructSize( $struct ) {
 546                 $size = 0;
 547                 foreach ( $struct as $type ) {
 548                         if ( is_array( $type ) ) {
 549                                 list( $typeName, $fieldSize ) = $type;
 550                                 $size += $fieldSize;
 551                         } else {
 552                                 $size += $type;
 553                         }
 554                 }
 555                 return $size;
 556         }
 557
 558         /**
 559          * Unpack a binary structure. This is like the built-in unpack() function
 560          * except nicer.
 561          *
 562          * @param $string The binary data input
 563          *
 564          * @param $struct An associative array giving structure members and their
 565          *    types. In the key is the field name. The value may be either an
 566          *    integer, in which case the field is a little-endian unsigned integer
 567          *    encoded in the given number of bytes, or an array, in which case the
 568          *    first element of the array is the type name, and the subsequent
 569          *    elements are type-dependent parameters. Only one such type is defined:
 570          *       - "string": The second array element gives the length of string.
 571          *          Not null terminated.
 572          *
 573          * @param $offset The offset into the string at which to start unpacking.
 574          *
 575          * @return Unpacked associative array. Note that large integers in the input
 576          *    may be represented as floating point numbers in the return value, so
 577          *    the use of weak comparison is advised.
 578          */
 579         function unpack( $string, $struct, $offset = 0 ) {
 580                 $size = $this->getStructSize( $struct );
 581                 if ( $offset + $size > strlen( $string ) ) {
 582                         $this->error( 'zip-bad', 'unpack() would run past the end of the supplied string' );
 583                 }
 584
 585                 $data = array();
 586                 $pos = $offset;
 587                 foreach ( $struct as $key => $type ) {
 588                         if ( is_array( $type ) ) {
 589                                 list( $typeName, $fieldSize ) = $type;
 590                                 switch ( $typeName ) {
 591                                 case 'string':
 592                                         $data[$key] = substr( $string, $pos, $fieldSize );
 593                                         $pos += $fieldSize;
 594                                         break;
 595                                 default:
 596                                         throw new MWException( __METHOD__.": invalid type \"$typeName\"" );
 597                                 }
 598                         } else {
 599                                 // Unsigned little-endian integer
 600                                 $length = intval( $type );
 601                                 $bytes = substr( $string, $pos, $length );
 602
 603                                 // Calculate the value. Use an algorithm which automatically
 604                                 // upgrades the value to floating point if necessary.
 605                                 $value = 0;
 606                                 for ( $i = $length - 1; $i >= 0; $i-- ) {
 607                                         $value *= 256;
 608                                         $value += ord( $string[$pos + $i] );
 609                                 }
 610
 611                                 // Throw an exception if there was loss of precision
 612                                 if ( $value > pow( 2, 52 ) ) {
 613                                         $this->error( 'zip-unsupported', 'number too large to be stored in a double. ' .
 614                                                 'This could happen if we tried to unpack a 64-bit structure ' .
 615                                                 'at an invalid location.' );
 616                                 }
 617                                 $data[$key] = $value;
 618                                 $pos += $length;
 619                         }
 620                 }
 621
 622                 return $data;
 623         }
 624
 625         /**
 626          * Returns a bit from a given position in an integer value, converted to
 627          * boolean.
 628          *
 629          * @param $value integer
 630          * @param $bitIndex The index of the bit, where 0 is the LSB.
 631          */
 632         function testBit( $value, $bitIndex ) {
 633                 return (bool)( ( $value >> $bitIndex ) & 1 );
 634         }
 635
 636         /**
 637          * Debugging helper function which dumps a string in hexdump -C format.
 638          */
 639         function hexDump( $s ) {
 640                 $n = strlen( $s );
 641                 for ( $i = 0; $i < $n; $i += 16 ) {
 642                         printf( "%08X ", $i );
 643                         for ( $j = 0; $j < 16; $j++ ) {
 644                                 print " ";
 645                                 if ( $j == 8 ) {
 646                                         print " ";
 647                                 }
 648                                 if ( $i + $j >= $n ) {
 649                                         print "  ";
 650                                 } else {
 651                                         printf( "%02X", ord( $s[$i + $j] ) );
 652                                 }
 653                         }
 654
 655                         print "  |";
 656                         for ( $j = 0; $j < 16; $j++ ) {
 657                                 if ( $i + $j >= $n ) {
 658                                         print " ";
 659                                 } elseif ( ctype_print( $s[$i + $j] ) ) {
 660                                         print $s[$i + $j];
 661                                 } else {
 662                                         print '.';
 663                                 }
 664                         }
 665                         print "|\n";
 666                 }
 667         }
 668 }
 669
 670 /**
 671  * Internal exception class. Will be caught by private code.
 672  */
 673 class ZipDirectoryReaderError extends Exception {
 674         var $code;
 675
 676         function __construct( $code ) {
 677                 $this->code = $code;
 678                 parent::__construct( "ZipDirectoryReader error: $code" );
 679         }
 680
 681         function getErrorCode() {
 682                 return $this->code;
 683         }
 684 }