includes/media/XMP.php

   1 <?php
   2 /**
   3  * Reader for XMP data containing properties relevant to images.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Media
  22  */
  23
  24 /**
  25  * Class for reading xmp data containing properties relevant to
  26  * images, and spitting out an array that FormatMetadata accepts.
  27  *
  28  * Note, this is not meant to recognize every possible thing you can
  29  * encode in XMP. It should recognize all the properties we want.
  30  * For example it doesn't have support for structures with multiple
  31  * nesting levels, as none of the properties we're supporting use that
  32  * feature. If it comes across properties it doesn't recognize, it should
  33  * ignore them.
  34  *
  35  * The public methods one would call in this class are
  36  * - parse( $content )
  37  *    Reads in xmp content.
  38  *    Can potentially be called multiple times with partial data each time.
  39  * - parseExtended( $content )
  40  *    Reads XMPExtended blocks (jpeg files only).
  41  * - getResults
  42  *    Outputs a results array.
  43  *
  44  * Note XMP kind of looks like rdf. They are not the same thing - XMP is
  45  * encoded as a specific subset of rdf. This class can read XMP. It cannot
  46  * read rdf.
  47  *
  48  */
  49 class XMPReader {
  50         /** @var array XMP item configuration array */
  51         protected $items;
  52
  53         /** @var array Array to hold the current element (and previous element, and so on) */
  54         private $curItem = array();
  55
  56         /** @var bool|string The structure name when processing nested structures. */
  57         private $ancestorStruct = false;
  58
  59         /** @var bool|string Temporary holder for character data that appears in xmp doc. */
  60         private $charContent = false;
  61
  62         /** @var array Stores the state the xmpreader is in (see MODE_FOO constants) */
  63         private $mode = array();
  64
  65         /** @var array Array to hold results */
  66         private $results = array();
  67
  68         /** @var bool If we're doing a seq or bag. */
  69         private $processingArray = false;
  70
  71         /** @var bool|string Used for lang alts only */
  72         private $itemLang = false;
  73
  74         /** @var resource A resource handle for the XML parser */
  75         private $xmlParser;
  76
  77         /** @var bool|string Character set like 'UTF-8' */
  78         private $charset = false;
  79
  80         /** @var int */
  81         private $extendedXMPOffset = 0;
  82
  83         /** @var int Flag determining if the XMP is safe to parse **/
  84         private $parsable = 0;
  85
  86         /** @var string Buffer of XML to parse **/
  87         private $xmlParsableBuffer = '';
  88
  89         /**
  90          * These are various mode constants.
  91          * they are used to figure out what to do
  92          * with an element when its encountered.
  93          *
  94          * For example, MODE_IGNORE is used when processing
  95          * a property we're not interested in. So if a new
  96          * element pops up when we're in that mode, we ignore it.
  97          */
  98         const MODE_INITIAL = 0;
  99         const MODE_IGNORE = 1;
 100         const MODE_LI = 2;
 101         const MODE_LI_LANG = 3;
 102         const MODE_QDESC = 4;
 103
 104         // The following MODE constants are also used in the
 105         // $items array to denote what type of property the item is.
 106         const MODE_SIMPLE = 10;
 107         const MODE_STRUCT = 11; // structure (associative array)
 108         const MODE_SEQ = 12; // ordered list
 109         const MODE_BAG = 13; // unordered list
 110         const MODE_LANG = 14;
 111         const MODE_ALT = 15; // non-language alt. Currently not implemented, and not needed atm.
 112         const MODE_BAGSTRUCT = 16; // A BAG of Structs.
 113
 114         const NS_RDF = 'http://www.w3.org/1999/02/22-rdf-syntax-ns#';
 115         const NS_XML = 'http://www.w3.org/XML/1998/namespace';
 116
 117         // States used while determining if XML is safe to parse
 118         const PARSABLE_UNKNOWN = 0;
 119         const PARSABLE_OK = 1;
 120         const PARSABLE_BUFFERING = 2;
 121         const PARSABLE_NO = 3;
 122
 123         /**
 124          * Constructor.
 125          *
 126          * Primary job is to initialize the XMLParser
 127          */
 128         function __construct() {
 129
 130                 if ( !function_exists( 'xml_parser_create_ns' ) ) {
 131                         // this should already be checked by this point
 132                         throw new MWException( 'XMP support requires XML Parser' );
 133                 }
 134
 135                 $this->items = XMPInfo::getItems();
 136
 137                 $this->resetXMLParser();
 138         }
 139
 140         /**
 141          * Main use is if a single item has multiple xmp documents describing it.
 142          * For example in jpeg's with extendedXMP
 143          */
 144         private function resetXMLParser() {
 145
 146                 if ( $this->xmlParser ) {
 147                         //is this needed?
 148                         xml_parser_free( $this->xmlParser );
 149                 }
 150
 151                 $this->xmlParser = xml_parser_create_ns( 'UTF-8', ' ' );
 152                 xml_parser_set_option( $this->xmlParser, XML_OPTION_CASE_FOLDING, 0 );
 153                 xml_parser_set_option( $this->xmlParser, XML_OPTION_SKIP_WHITE, 1 );
 154
 155                 xml_set_element_handler( $this->xmlParser,
 156                         array( $this, 'startElement' ),
 157                         array( $this, 'endElement' ) );
 158
 159                 xml_set_character_data_handler( $this->xmlParser, array( $this, 'char' ) );
 160
 161                 $this->parsable = self::PARSABLE_UNKNOWN;
 162                 $this->xmlParsableBuffer = '';
 163         }
 164
 165         /** Destroy the xml parser
 166          *
 167          * Not sure if this is actually needed.
 168          */
 169         function __destruct() {
 170                 // not sure if this is needed.
 171                 xml_parser_free( $this->xmlParser );
 172         }
 173
 174         /**
 175          * Check if this instance supports using this class
 176          */
 177         public static function isSupported() {
 178                 return function_exists( 'xml_parser_create_ns' ) && class_exists( 'XMLReader' );
 179         }
 180
 181         /** Get the result array. Do some post-processing before returning
 182          * the array, and transform any metadata that is special-cased.
 183          *
 184          * @return array Array of results as an array of arrays suitable for
 185          *    FormatMetadata::getFormattedData().
 186          */
 187         public function getResults() {
 188                 // xmp-special is for metadata that affects how stuff
 189                 // is extracted. For example xmpNote:HasExtendedXMP.
 190
 191                 // It is also used to handle photoshop:AuthorsPosition
 192                 // which is weird and really part of another property,
 193                 // see 2:85 in IPTC. See also pg 21 of IPTC4XMP standard.
 194                 // The location fields also use it.
 195
 196                 $data = $this->results;
 197
 198                 if ( isset( $data['xmp-special']['AuthorsPosition'] )
 199                         && is_string( $data['xmp-special']['AuthorsPosition'] )
 200                         && isset( $data['xmp-general']['Artist'][0] )
 201                 ) {
 202                         // Note, if there is more than one creator,
 203                         // this only applies to first. This also will
 204                         // only apply to the dc:Creator prop, not the
 205                         // exif:Artist prop.
 206
 207                         $data['xmp-general']['Artist'][0] =
 208                                 $data['xmp-special']['AuthorsPosition'] . ', '
 209                                 . $data['xmp-general']['Artist'][0];
 210                 }
 211
 212                 // Go through the LocationShown and LocationCreated
 213                 // changing it to the non-hierarchal form used by
 214                 // the other location fields.
 215
 216                 if ( isset( $data['xmp-special']['LocationShown'][0] )
 217                         && is_array( $data['xmp-special']['LocationShown'][0] )
 218                 ) {
 219                         // the is_array is just paranoia. It should always
 220                         // be an array.
 221                         foreach ( $data['xmp-special']['LocationShown'] as $loc ) {
 222                                 if ( !is_array( $loc ) ) {
 223                                         // To avoid copying over the _type meta-fields.
 224                                         continue;
 225                                 }
 226                                 foreach ( $loc as $field => $val ) {
 227                                         $data['xmp-general'][$field . 'Dest'][] = $val;
 228                                 }
 229                         }
 230                 }
 231                 if ( isset( $data['xmp-special']['LocationCreated'][0] )
 232                         && is_array( $data['xmp-special']['LocationCreated'][0] )
 233                 ) {
 234                         // the is_array is just paranoia. It should always
 235                         // be an array.
 236                         foreach ( $data['xmp-special']['LocationCreated'] as $loc ) {
 237                                 if ( !is_array( $loc ) ) {
 238                                         // To avoid copying over the _type meta-fields.
 239                                         continue;
 240                                 }
 241                                 foreach ( $loc as $field => $val ) {
 242                                         $data['xmp-general'][$field . 'Created'][] = $val;
 243                                 }
 244                         }
 245                 }
 246
 247                 // We don't want to return the special values, since they're
 248                 // special and not info to be stored about the file.
 249                 unset( $data['xmp-special'] );
 250
 251                 // Convert GPSAltitude to negative if below sea level.
 252                 if ( isset( $data['xmp-exif']['GPSAltitudeRef'] )
 253                         && isset( $data['xmp-exif']['GPSAltitude'] )
 254                 ) {
 255
 256                         // Must convert to a real before multiplying by -1
 257                         // XMPValidate guarantees there will always be a '/' in this value.
 258                         list( $nom, $denom ) = explode( '/', $data['xmp-exif']['GPSAltitude'] );
 259                         $data['xmp-exif']['GPSAltitude'] = $nom / $denom;
 260
 261                         if ( $data['xmp-exif']['GPSAltitudeRef'] == '1' ) {
 262                                 $data['xmp-exif']['GPSAltitude'] *= -1;
 263                         }
 264                         unset( $data['xmp-exif']['GPSAltitudeRef'] );
 265                 }
 266
 267                 return $data;
 268         }
 269
 270         /**
 271          * Main function to call to parse XMP. Use getResults to
 272          * get results.
 273          *
 274          * Also catches any errors during processing, writes them to
 275          * debug log, blanks result array and returns false.
 276          *
 277          * @param string $content XMP data
 278          * @param bool $allOfIt If this is all the data (true) or if its split up (false). Default true
 279          * @param bool $reset Does xml parser need to be reset. Default false
 280          * @throws MWException
 281          * @return bool Success.
 282          */
 283         public function parse( $content, $allOfIt = true, $reset = false ) {
 284                 if ( $reset ) {
 285                         $this->resetXMLParser();
 286                 }
 287                 try {
 288
 289                         // detect encoding by looking for BOM which is supposed to be in processing instruction.
 290                         // see page 12 of http://www.adobe.com/devnet/xmp/pdfs/XMPSpecificationPart3.pdf
 291                         if ( !$this->charset ) {
 292                                 $bom = array();
 293                                 if ( preg_match( '/\xEF\xBB\xBF|\xFE\xFF|\x00\x00\xFE\xFF|\xFF\xFE\x00\x00|\xFF\xFE/',
 294                                         $content, $bom )
 295                                 ) {
 296                                         switch ( $bom[0] ) {
 297                                                 case "\xFE\xFF":
 298                                                         $this->charset = 'UTF-16BE';
 299                                                         break;
 300                                                 case "\xFF\xFE":
 301                                                         $this->charset = 'UTF-16LE';
 302                                                         break;
 303                                                 case "\x00\x00\xFE\xFF":
 304                                                         $this->charset = 'UTF-32BE';
 305                                                         break;
 306                                                 case "\xFF\xFE\x00\x00":
 307                                                         $this->charset = 'UTF-32LE';
 308                                                         break;
 309                                                 case "\xEF\xBB\xBF":
 310                                                         $this->charset = 'UTF-8';
 311                                                         break;
 312                                                 default:
 313                                                         //this should be impossible to get to
 314                                                         throw new MWException( "Invalid BOM" );
 315                                         }
 316                                 } else {
 317                                         // standard specifically says, if no bom assume utf-8
 318                                         $this->charset = 'UTF-8';
 319                                 }
 320                         }
 321                         if ( $this->charset !== 'UTF-8' ) {
 322                                 //don't convert if already utf-8
 323                                 wfSuppressWarnings();
 324                                 $content = iconv( $this->charset, 'UTF-8//IGNORE', $content );
 325                                 wfRestoreWarnings();
 326                         }
 327
 328                         // Ensure the XMP block does not have an xml doctype declaration, which
 329                         // could declare entities unsafe to parse with xml_parse (T85848/T71210).
 330                         if ( $this->parsable !== self::PARSABLE_OK ) {
 331                                 if ( $this->parsable === self::PARSABLE_NO ) {
 332                                         throw new Exception( 'Unsafe doctype declaration in XML.' );
 333                                 }
 334
 335                                 $content = $this->xmlParsableBuffer . $content;
 336                                 if ( !$this->checkParseSafety( $content ) ) {
 337                                         if ( !$allOfIt && $this->parsable !== self::PARSABLE_NO ) {
 338                                                 // parse wasn't Unsuccessful yet, so return true
 339                                                 // in this case.
 340                                                 return true;
 341                                         }
 342                                         $msg = ( $this->parsable === self::PARSABLE_NO ) ?
 343                                                 'Unsafe doctype declaration in XML.' :
 344                                                 'No root element found in XML.';
 345                                         throw new Exception( $msg );
 346                                 }
 347                         }
 348
 349                         $ok = xml_parse( $this->xmlParser, $content, $allOfIt );
 350                         if ( !$ok ) {
 351                                 $error = xml_error_string( xml_get_error_code( $this->xmlParser ) );
 352                                 $where = 'line: ' . xml_get_current_line_number( $this->xmlParser )
 353                                         . ' column: ' . xml_get_current_column_number( $this->xmlParser )
 354                                         . ' byte offset: ' . xml_get_current_byte_index( $this->xmlParser );
 355
 356                                 wfDebugLog( 'XMP', "XMPReader::parse : Error reading XMP content: $error ($where)" );
 357                                 $this->results = array(); // blank if error.
 358                                 return false;
 359                         }
 360                 } catch ( Exception $e ) {
 361                         wfDebugLog( 'XMP', 'XMP parse error: ' . $e );
 362                         $this->results = array();
 363
 364                         return false;
 365                 }
 366
 367                 return true;
 368         }
 369
 370         /** Entry point for XMPExtended blocks in jpeg files
 371          *
 372          * @todo In serious need of testing
 373          * @see http://www.adobe.ge/devnet/xmp/pdfs/XMPSpecificationPart3.pdf XMP spec part 3 page 20
 374          * @param string $content XMPExtended block minus the namespace signature
 375          * @return bool If it succeeded.
 376          */
 377         public function parseExtended( $content ) {
 378                 // @todo FIXME: This is untested. Hard to find example files
 379                 // or programs that make such files..
 380                 $guid = substr( $content, 0, 32 );
 381                 if ( !isset( $this->results['xmp-special']['HasExtendedXMP'] )
 382                         || $this->results['xmp-special']['HasExtendedXMP'] !== $guid
 383                 ) {
 384                         wfDebugLog( 'XMP', __METHOD__ .
 385                                 " Ignoring XMPExtended block due to wrong guid (guid= '$guid')" );
 386
 387                         return false;
 388                 }
 389                 $len = unpack( 'Nlength/Noffset', substr( $content, 32, 8 ) );
 390
 391                 if ( !$len || $len['length'] < 4 || $len['offset'] < 0 || $len['offset'] > $len['length'] ) {
 392                         wfDebugLog( 'XMP', __METHOD__ . 'Error reading extended XMP block, invalid length or offset.' );
 393
 394                         return false;
 395                 }
 396
 397                 // we're not very robust here. we should accept it in the wrong order.
 398                 // To quote the XMP standard:
 399                 // "A JPEG writer should write the ExtendedXMP marker segments in order,
 400                 // immediately following the StandardXMP. However, the JPEG standard
 401                 // does not require preservation of marker segment order. A robust JPEG
 402                 // reader should tolerate the marker segments in any order."
 403                 //
 404                 // otoh the probability that an image will have more than 128k of
 405                 // metadata is rather low... so the probability that it will have
 406                 // > 128k, and be in the wrong order is very low...
 407
 408                 if ( $len['offset'] !== $this->extendedXMPOffset ) {
 409                         wfDebugLog( 'XMP', __METHOD__ . 'Ignoring XMPExtended block due to wrong order. (Offset was '
 410                                 . $len['offset'] . ' but expected ' . $this->extendedXMPOffset . ')' );
 411
 412                         return false;
 413                 }
 414
 415                 if ( $len['offset'] === 0 ) {
 416                         // if we're starting the extended block, we've probably already
 417                         // done the XMPStandard block, so reset.
 418                         $this->resetXMLParser();
 419                 }
 420
 421                 $this->extendedXMPOffset += $len['length'];
 422
 423                 $actualContent = substr( $content, 40 );
 424
 425                 if ( $this->extendedXMPOffset === strlen( $actualContent ) ) {
 426                         $atEnd = true;
 427                 } else {
 428                         $atEnd = false;
 429                 }
 430
 431                 wfDebugLog( 'XMP', __METHOD__ . 'Parsing a XMPExtended block' );
 432
 433                 return $this->parse( $actualContent, $atEnd );
 434         }
 435
 436         /**
 437          * Character data handler
 438          * Called whenever character data is found in the xmp document.
 439          *
 440          * does nothing if we're in MODE_IGNORE or if the data is whitespace
 441          * throws an error if we're not in MODE_SIMPLE (as we're not allowed to have character
 442          * data in the other modes).
 443          *
 444          * As an example, this happens when we encounter XMP like:
 445          * <exif:DigitalZoomRatio>0/10</exif:DigitalZoomRatio>
 446          * and are processing the 0/10 bit.
 447          *
 448          * @param XMLParser $parser XMLParser reference to the xml parser
 449          * @param string $data Character data
 450          * @throws MWException On invalid data
 451          */
 452         function char( $parser, $data ) {
 453
 454                 $data = trim( $data );
 455                 if ( trim( $data ) === "" ) {
 456                         return;
 457                 }
 458
 459                 if ( !isset( $this->mode[0] ) ) {
 460                         throw new MWException( 'Unexpected character data before first rdf:Description element' );
 461                 }
 462
 463                 if ( $this->mode[0] === self::MODE_IGNORE ) {
 464                         return;
 465                 }
 466
 467                 if ( $this->mode[0] !== self::MODE_SIMPLE
 468                         && $this->mode[0] !== self::MODE_QDESC
 469                 ) {
 470                         throw new MWException( 'character data where not expected. (mode ' . $this->mode[0] . ')' );
 471                 }
 472
 473                 // to check, how does this handle w.s.
 474                 if ( $this->charContent === false ) {
 475                         $this->charContent = $data;
 476                 } else {
 477                         $this->charContent .= $data;
 478                 }
 479         }
 480
 481         /**
 482          * Check if a block of XML is safe to pass to xml_parse, i.e. doesn't
 483          * contain a doctype declaration which could contain a dos attack if we
 484          * parse it and expand internal entities (T85848).
 485          *
 486          * @param string $content xml string to check for parse safety
 487          * @return bool true if the xml is safe to parse, false otherwise
 488          */
 489         private function checkParseSafety( $content ) {
 490                 $reader = new XMLReader();
 491                 $result = null;
 492
 493                 // For XMLReader to parse incomplete/invalid XML, it has to be open()'ed
 494                 // instead of using XML().
 495                 $reader->open(
 496                         'data://text/plain,' . urlencode( $content ),
 497                         null,
 498                         LIBXML_NOERROR | LIBXML_NOWARNING | LIBXML_NONET
 499                 );
 500
 501                 $oldDisable = libxml_disable_entity_loader( true );
 502                 $reset = new ScopedCallback(
 503                         'libxml_disable_entity_loader',
 504                         array( $oldDisable )
 505                 );
 506                 $reader->setParserProperty( XMLReader::SUBST_ENTITIES, false );
 507
 508                 // Even with LIBXML_NOWARNING set, XMLReader::read gives a warning
 509                 // when parsing truncated XML, which causes unit tests to fail.
 510                 wfSuppressWarnings();
 511                 while ( $reader->read() ) {
 512                         if ( $reader->nodeType === XMLReader::ELEMENT ) {
 513                                 // Reached the first element without hitting a doctype declaration
 514                                 $this->parsable = self::PARSABLE_OK;
 515                                 $result = true;
 516                                 break;
 517                         }
 518                         if ( $reader->nodeType === XMLReader::DOC_TYPE ) {
 519                                 $this->parsable = self::PARSABLE_NO;
 520                                 $result = false;
 521                                 break;
 522                         }
 523                 }
 524                 wfRestoreWarnings();
 525
 526                 if ( !is_null( $result ) ) {
 527                         return $result;
 528                 }
 529
 530                 // Reached the end of the parsable xml without finding an element
 531                 // or doctype. Buffer and try again.
 532                 $this->parsable = self::PARSABLE_BUFFERING;
 533                 $this->xmlParsableBuffer = $content;
 534                 return false;
 535         }
 536
 537         /** When we hit a closing element in MODE_IGNORE
 538          * Check to see if this is the element we started to ignore,
 539          * in which case we get out of MODE_IGNORE
 540          *
 541          * @param string $elm Namespace of element followed by a space and then tag name of element.
 542          */
 543         private function endElementModeIgnore( $elm ) {
 544                 if ( $this->curItem[0] === $elm ) {
 545                         array_shift( $this->curItem );
 546                         array_shift( $this->mode );
 547                 }
 548         }
 549
 550         /**
 551          * Hit a closing element when in MODE_SIMPLE.
 552          * This generally means that we finished processing a
 553          * property value, and now have to save the result to the
 554          * results array
 555          *
 556          * For example, when processing:
 557          * <exif:DigitalZoomRatio>0/10</exif:DigitalZoomRatio>
 558          * this deals with when we hit </exif:DigitalZoomRatio>.
 559          *
 560          * Or it could be if we hit the end element of a property
 561          * of a compound data structure (like a member of an array).
 562          *
 563          * @param string $elm Namespace, space, and tag name.
 564          */
 565         private function endElementModeSimple( $elm ) {
 566                 if ( $this->charContent !== false ) {
 567                         if ( $this->processingArray ) {
 568                                 // if we're processing an array, use the original element
 569                                 // name instead of rdf:li.
 570                                 list( $ns, $tag ) = explode( ' ', $this->curItem[0], 2 );
 571                         } else {
 572                                 list( $ns, $tag ) = explode( ' ', $elm, 2 );
 573                         }
 574                         $this->saveValue( $ns, $tag, $this->charContent );
 575
 576                         $this->charContent = false; // reset
 577                 }
 578                 array_shift( $this->curItem );
 579                 array_shift( $this->mode );
 580         }
 581
 582         /**
 583          * Hit a closing element in MODE_STRUCT, MODE_SEQ, MODE_BAG
 584          * generally means we've finished processing a nested structure.
 585          * resets some internal variables to indicate that.
 586          *
 587          * Note this means we hit the closing element not the "</rdf:Seq>".
 588          *
 589          * @par For example, when processing:
 590          * @code{,xml}
 591          * <exif:ISOSpeedRatings> <rdf:Seq> <rdf:li>64</rdf:li>
 592          *   </rdf:Seq> </exif:ISOSpeedRatings>
 593          * @endcode
 594          *
 595          * This method is called when we hit the "</exif:ISOSpeedRatings>" tag.
 596          *
 597          * @param string $elm Namespace . space . tag name.
 598          * @throws MWException
 599          */
 600         private function endElementNested( $elm ) {
 601
 602                 /* cur item must be the same as $elm, unless if in MODE_STRUCT
 603                    in which case it could also be rdf:Description */
 604                 if ( $this->curItem[0] !== $elm
 605                         && !( $elm === self::NS_RDF . ' Description'
 606                                 && $this->mode[0] === self::MODE_STRUCT )
 607                 ) {
 608                         throw new MWException( "nesting mismatch. got a </$elm> but expected a </" .
 609                                 $this->curItem[0] . '>' );
 610                 }
 611
 612                 // Validate structures.
 613                 list( $ns, $tag ) = explode( ' ', $elm, 2 );
 614                 if ( isset( $this->items[$ns][$tag]['validate'] ) ) {
 615
 616                         $info =& $this->items[$ns][$tag];
 617                         $finalName = isset( $info['map_name'] )
 618                                 ? $info['map_name'] : $tag;
 619
 620                         $validate = is_array( $info['validate'] ) ? $info['validate']
 621                                 : array( 'XMPValidate', $info['validate'] );
 622
 623                         if ( !isset( $this->results['xmp-' . $info['map_group']][$finalName] ) ) {
 624                                 // This can happen if all the members of the struct failed validation.
 625                                 wfDebugLog( 'XMP', __METHOD__ . " <$ns:$tag> has no valid members." );
 626                         } elseif ( is_callable( $validate ) ) {
 627                                 $val =& $this->results['xmp-' . $info['map_group']][$finalName];
 628                                 call_user_func_array( $validate, array( $info, &$val, false ) );
 629                                 if ( is_null( $val ) ) {
 630                                         // the idea being the validation function will unset the variable if
 631                                         // its invalid.
 632                                         wfDebugLog( 'XMP', __METHOD__ . " <$ns:$tag> failed validation." );
 633                                         unset( $this->results['xmp-' . $info['map_group']][$finalName] );
 634                                 }
 635                         } else {
 636                                 wfDebugLog( 'XMP', __METHOD__ . " Validation function for $finalName ("
 637                                         . $validate[0] . '::' . $validate[1] . '()) is not callable.' );
 638                         }
 639                 }
 640
 641                 array_shift( $this->curItem );
 642                 array_shift( $this->mode );
 643                 $this->ancestorStruct = false;
 644                 $this->processingArray = false;
 645                 $this->itemLang = false;
 646         }
 647
 648         /**
 649          * Hit a closing element in MODE_LI (either rdf:Seq, or rdf:Bag )
 650          * Add information about what type of element this is.
 651          *
 652          * Note we still have to hit the outer "</property>"
 653          *
 654          * @par For example, when processing:
 655          * @code{,xml}
 656          * <exif:ISOSpeedRatings> <rdf:Seq> <rdf:li>64</rdf:li>
 657          *   </rdf:Seq> </exif:ISOSpeedRatings>
 658          * @endcode
 659          *
 660          * This method is called when we hit the "</rdf:Seq>".
 661          * (For comparison, we call endElementModeSimple when we
 662          * hit the "</rdf:li>")
 663          *
 664          * @param string $elm Namespace . ' ' . element name
 665          * @throws MWException
 666          */
 667         private function endElementModeLi( $elm ) {
 668
 669                 list( $ns, $tag ) = explode( ' ', $this->curItem[0], 2 );
 670                 $info = $this->items[$ns][$tag];
 671                 $finalName = isset( $info['map_name'] )
 672                         ? $info['map_name'] : $tag;
 673
 674                 array_shift( $this->mode );
 675
 676                 if ( !isset( $this->results['xmp-' . $info['map_group']][$finalName] ) ) {
 677                         wfDebugLog( 'XMP', __METHOD__ . " Empty compund element $finalName." );
 678
 679                         return;
 680                 }
 681
 682                 if ( $elm === self::NS_RDF . ' Seq' ) {
 683                         $this->results['xmp-' . $info['map_group']][$finalName]['_type'] = 'ol';
 684                 } elseif ( $elm === self::NS_RDF . ' Bag' ) {
 685                         $this->results['xmp-' . $info['map_group']][$finalName]['_type'] = 'ul';
 686                 } elseif ( $elm === self::NS_RDF . ' Alt' ) {
 687                         // extra if needed as you could theoretically have a non-language alt.
 688                         if ( $info['mode'] === self::MODE_LANG ) {
 689                                 $this->results['xmp-' . $info['map_group']][$finalName]['_type'] = 'lang';
 690                         }
 691                 } else {
 692                         throw new MWException( __METHOD__ . " expected </rdf:seq> or </rdf:bag> but instead got $elm." );
 693                 }
 694         }
 695
 696         /**
 697          * End element while in MODE_QDESC
 698          * mostly when ending an element when we have a simple value
 699          * that has qualifiers.
 700          *
 701          * Qualifiers aren't all that common, and we don't do anything
 702          * with them.
 703          *
 704          * @param string $elm Namespace and element
 705          */
 706         private function endElementModeQDesc( $elm ) {
 707
 708                 if ( $elm === self::NS_RDF . ' value' ) {
 709                         list( $ns, $tag ) = explode( ' ', $this->curItem[0], 2 );
 710                         $this->saveValue( $ns, $tag, $this->charContent );
 711
 712                         return;
 713                 } else {
 714                         array_shift( $this->mode );
 715                         array_shift( $this->curItem );
 716                 }
 717         }
 718
 719         /**
 720          * Handler for hitting a closing element.
 721          *
 722          * generally just calls a helper function depending on what
 723          * mode we're in.
 724          *
 725          * Ignores the outer wrapping elements that are optional in
 726          * xmp and have no meaning.
 727          *
 728          * @param XMLParser $parser
 729          * @param string $elm Namespace . ' ' . element name
 730          * @throws MWException
 731          */
 732         function endElement( $parser, $elm ) {
 733                 if ( $elm === ( self::NS_RDF . ' RDF' )
 734                         || $elm === 'adobe:ns:meta/ xmpmeta'
 735                         || $elm === 'adobe:ns:meta/ xapmeta'
 736                 ) {
 737                         // ignore these.
 738                         return;
 739                 }
 740
 741                 if ( $elm === self::NS_RDF . ' type' ) {
 742                         // these aren't really supported properly yet.
 743                         // However, it appears they almost never used.
 744                         wfDebugLog( 'XMP', __METHOD__ . ' encountered <rdf:type>' );
 745                 }
 746
 747                 if ( strpos( $elm, ' ' ) === false ) {
 748                         // This probably shouldn't happen.
 749                         // However, there is a bug in an adobe product
 750                         // that forgets the namespace on some things.
 751                         // (Luckily they are unimportant things).
 752                         wfDebugLog( 'XMP', __METHOD__ . " Encountered </$elm> which has no namespace. Skipping." );
 753
 754                         return;
 755                 }
 756
 757                 if ( count( $this->mode[0] ) === 0 ) {
 758                         // This should never ever happen and means
 759                         // there is a pretty major bug in this class.
 760                         throw new MWException( 'Encountered end element with no mode' );
 761                 }
 762
 763                 if ( count( $this->curItem ) == 0 && $this->mode[0] !== self::MODE_INITIAL ) {
 764                         // just to be paranoid. Should always have a curItem, except for initially
 765                         // (aka during MODE_INITAL).
 766                         throw new MWException( "Hit end element </$elm> but no curItem" );
 767                 }
 768
 769                 switch ( $this->mode[0] ) {
 770                         case self::MODE_IGNORE:
 771                                 $this->endElementModeIgnore( $elm );
 772                                 break;
 773                         case self::MODE_SIMPLE:
 774                                 $this->endElementModeSimple( $elm );
 775                                 break;
 776                         case self::MODE_STRUCT:
 777                         case self::MODE_SEQ:
 778                         case self::MODE_BAG:
 779                         case self::MODE_LANG:
 780                         case self::MODE_BAGSTRUCT:
 781                                 $this->endElementNested( $elm );
 782                                 break;
 783                         case self::MODE_INITIAL:
 784                                 if ( $elm === self::NS_RDF . ' Description' ) {
 785                                         array_shift( $this->mode );
 786                                 } else {
 787                                         throw new MWException( 'Element ended unexpectedly while in MODE_INITIAL' );
 788                                 }
 789                                 break;
 790                         case self::MODE_LI:
 791                         case self::MODE_LI_LANG:
 792                                 $this->endElementModeLi( $elm );
 793                                 break;
 794                         case self::MODE_QDESC:
 795                                 $this->endElementModeQDesc( $elm );
 796                                 break;
 797                         default:
 798                                 wfDebugLog( 'XMP', __METHOD__ . " no mode (elm = $elm)" );
 799                                 break;
 800                 }
 801         }
 802
 803         /**
 804          * Hit an opening element while in MODE_IGNORE
 805          *
 806          * XMP is extensible, so ignore any tag we don't understand.
 807          *
 808          * Mostly ignores, unless we encounter the element that we are ignoring.
 809          * in which case we add it to the item stack, so we can ignore things
 810          * that are nested, correctly.
 811          *
 812          * @param string $elm Namespace . ' ' . tag name
 813          */
 814         private function startElementModeIgnore( $elm ) {
 815                 if ( $elm === $this->curItem[0] ) {
 816                         array_unshift( $this->curItem, $elm );
 817                         array_unshift( $this->mode, self::MODE_IGNORE );
 818                 }
 819         }
 820
 821         /**
 822          *  Start element in MODE_BAG (unordered array)
 823          * this should always be <rdf:Bag>
 824          *
 825          * @param string $elm Namespace . ' ' . tag
 826          * @throws MWException If we have an element that's not <rdf:Bag>
 827          */
 828         private function startElementModeBag( $elm ) {
 829                 if ( $elm === self::NS_RDF . ' Bag' ) {
 830                         array_unshift( $this->mode, self::MODE_LI );
 831                 } else {
 832                         throw new MWException( "Expected <rdf:Bag> but got $elm." );
 833                 }
 834         }
 835
 836         /**
 837          * Start element in MODE_SEQ (ordered array)
 838          * this should always be <rdf:Seq>
 839          *
 840          * @param string $elm Namespace . ' ' . tag
 841          * @throws MWException If we have an element that's not <rdf:Seq>
 842          */
 843         private function startElementModeSeq( $elm ) {
 844                 if ( $elm === self::NS_RDF . ' Seq' ) {
 845                         array_unshift( $this->mode, self::MODE_LI );
 846                 } elseif ( $elm === self::NS_RDF . ' Bag' ) {
 847                         # bug 27105
 848                         wfDebugLog( 'XMP', __METHOD__ . ' Expected an rdf:Seq, but got an rdf:Bag. Pretending'
 849                                 . ' it is a Seq, since some buggy software is known to screw this up.' );
 850                         array_unshift( $this->mode, self::MODE_LI );
 851                 } else {
 852                         throw new MWException( "Expected <rdf:Seq> but got $elm." );
 853                 }
 854         }
 855
 856         /**
 857          * Start element in MODE_LANG (language alternative)
 858          * this should always be <rdf:Alt>
 859          *
 860          * This tag tends to be used for metadata like describe this
 861          * picture, which can be translated into multiple languages.
 862          *
 863          * XMP supports non-linguistic alternative selections,
 864          * which are really only used for thumbnails, which
 865          * we don't care about.
 866          *
 867          * @param string $elm Namespace . ' ' . tag
 868          * @throws MWException If we have an element that's not <rdf:Alt>
 869          */
 870         private function startElementModeLang( $elm ) {
 871                 if ( $elm === self::NS_RDF . ' Alt' ) {
 872                         array_unshift( $this->mode, self::MODE_LI_LANG );
 873                 } else {
 874                         throw new MWException( "Expected <rdf:Seq> but got $elm." );
 875                 }
 876         }
 877
 878         /**
 879          * Handle an opening element when in MODE_SIMPLE
 880          *
 881          * This should not happen often. This is for if a simple element
 882          * already opened has a child element. Could happen for a
 883          * qualified element.
 884          *
 885          * For example:
 886          * <exif:DigitalZoomRatio><rdf:Description><rdf:value>0/10</rdf:value>
 887          *   <foo:someQualifier>Bar</foo:someQualifier> </rdf:Description>
 888          *   </exif:DigitalZoomRatio>
 889          *
 890          * This method is called when processing the <rdf:Description> element
 891          *
 892          * @param string $elm Namespace and tag names separated by space.
 893          * @param array $attribs Attributes of the element.
 894          * @throws MWException
 895          */
 896         private function startElementModeSimple( $elm, $attribs ) {
 897                 if ( $elm === self::NS_RDF . ' Description' ) {
 898                         // If this value has qualifiers
 899                         array_unshift( $this->mode, self::MODE_QDESC );
 900                         array_unshift( $this->curItem, $this->curItem[0] );
 901
 902                         if ( isset( $attribs[self::NS_RDF . ' value'] ) ) {
 903                                 list( $ns, $tag ) = explode( ' ', $this->curItem[0], 2 );
 904                                 $this->saveValue( $ns, $tag, $attribs[self::NS_RDF . ' value'] );
 905                         }
 906                 } elseif ( $elm === self::NS_RDF . ' value' ) {
 907                         // This should not be here.
 908                         throw new MWException( __METHOD__ . ' Encountered <rdf:value> where it was unexpected.' );
 909                 } else {
 910                         // something else we don't recognize, like a qualifier maybe.
 911                         wfDebugLog( 'XMP', __METHOD__ .
 912                                 " Encountered element <$elm> where only expecting character data as value of " .
 913                                 $this->curItem[0] );
 914                         array_unshift( $this->mode, self::MODE_IGNORE );
 915                         array_unshift( $this->curItem, $elm );
 916                 }
 917         }
 918
 919         /**
 920          * Start an element when in MODE_QDESC.
 921          * This generally happens when a simple element has an inner
 922          * rdf:Description to hold qualifier elements.
 923          *
 924          * For example in:
 925          * <exif:DigitalZoomRatio><rdf:Description><rdf:value>0/10</rdf:value>
 926          *   <foo:someQualifier>Bar</foo:someQualifier> </rdf:Description>
 927          *   </exif:DigitalZoomRatio>
 928          * Called when processing the <rdf:value> or <foo:someQualifier>.
 929          *
 930          * @param string $elm Namespace and tag name separated by a space.
 931          *
 932          */
 933         private function startElementModeQDesc( $elm ) {
 934                 if ( $elm === self::NS_RDF . ' value' ) {
 935                         return; // do nothing
 936                 } else {
 937                         // otherwise its a qualifier, which we ignore
 938                         array_unshift( $this->mode, self::MODE_IGNORE );
 939                         array_unshift( $this->curItem, $elm );
 940                 }
 941         }
 942
 943         /**
 944          * Starting an element when in MODE_INITIAL
 945          * This usually happens when we hit an element inside
 946          * the outer rdf:Description
 947          *
 948          * This is generally where most properties start.
 949          *
 950          * @param string $ns Namespace
 951          * @param string $tag Tag name (without namespace prefix)
 952          * @param array $attribs Array of attributes
 953          * @throws MWException
 954          */
 955         private function startElementModeInitial( $ns, $tag, $attribs ) {
 956                 if ( $ns !== self::NS_RDF ) {
 957
 958                         if ( isset( $this->items[$ns][$tag] ) ) {
 959                                 if ( isset( $this->items[$ns][$tag]['structPart'] ) ) {
 960                                         // If this element is supposed to appear only as
 961                                         // a child of a structure, but appears here (not as
 962                                         // a child of a struct), then something weird is
 963                                         // happening, so ignore this element and its children.
 964
 965                                         wfDebugLog( 'XMP', "Encountered <$ns:$tag> outside"
 966                                                 . " of its expected parent. Ignoring." );
 967
 968                                         array_unshift( $this->mode, self::MODE_IGNORE );
 969                                         array_unshift( $this->curItem, $ns . ' ' . $tag );
 970
 971                                         return;
 972                                 }
 973                                 $mode = $this->items[$ns][$tag]['mode'];
 974                                 array_unshift( $this->mode, $mode );
 975                                 array_unshift( $this->curItem, $ns . ' ' . $tag );
 976                                 if ( $mode === self::MODE_STRUCT ) {
 977                                         $this->ancestorStruct = isset( $this->items[$ns][$tag]['map_name'] )
 978                                                 ? $this->items[$ns][$tag]['map_name'] : $tag;
 979                                 }
 980                                 if ( $this->charContent !== false ) {
 981                                         // Something weird.
 982                                         // Should not happen in valid XMP.
 983                                         throw new MWException( 'tag nested in non-whitespace characters.' );
 984                                 }
 985                         } else {
 986                                 // This element is not on our list of allowed elements so ignore.
 987                                 wfDebugLog( 'XMP', __METHOD__ . " Ignoring unrecognized element <$ns:$tag>." );
 988                                 array_unshift( $this->mode, self::MODE_IGNORE );
 989                                 array_unshift( $this->curItem, $ns . ' ' . $tag );
 990
 991                                 return;
 992                         }
 993                 }
 994                 // process attributes
 995                 $this->doAttribs( $attribs );
 996         }
 997
 998         /**
 999          * Hit an opening element when in a Struct (MODE_STRUCT)
1000          * This is generally for fields of a compound property.
1001          *
1002          * Example of a struct (abbreviated; flash has more properties):
1003          *
1004          * <exif:Flash> <rdf:Description> <exif:Fired>True</exif:Fired>
1005          *  <exif:Mode>1</exif:Mode></rdf:Description></exif:Flash>
1006          *
1007          * or:
1008          *
1009          * <exif:Flash rdf:parseType='Resource'> <exif:Fired>True</exif:Fired>
1010          *  <exif:Mode>1</exif:Mode></exif:Flash>
1011          *
1012          * @param string $ns Namespace
1013          * @param string $tag Tag name (no ns)
1014          * @param array $attribs Array of attribs w/ values.
1015          * @throws MWException
1016          */
1017         private function startElementModeStruct( $ns, $tag, $attribs ) {
1018                 if ( $ns !== self::NS_RDF ) {
1019
1020                         if ( isset( $this->items[$ns][$tag] ) ) {
1021                                 if ( isset( $this->items[$ns][$this->ancestorStruct]['children'] )
1022                                         && !isset( $this->items[$ns][$this->ancestorStruct]['children'][$tag] )
1023                                 ) {
1024                                         // This assumes that we don't have inter-namespace nesting
1025                                         // which we don't in all the properties we're interested in.
1026                                         throw new MWException( " <$tag> appeared nested in <" . $this->ancestorStruct
1027                                                 . "> where it is not allowed." );
1028                                 }
1029                                 array_unshift( $this->mode, $this->items[$ns][$tag]['mode'] );
1030                                 array_unshift( $this->curItem, $ns . ' ' . $tag );
1031                                 if ( $this->charContent !== false ) {
1032                                         // Something weird.
1033                                         // Should not happen in valid XMP.
1034                                         throw new MWException( "tag <$tag> nested in non-whitespace characters (" .
1035                                                 $this->charContent . ")." );
1036                                 }
1037                         } else {
1038                                 array_unshift( $this->mode, self::MODE_IGNORE );
1039                                 array_unshift( $this->curItem, $elm );
1040
1041                                 return;
1042                         }
1043                 }
1044
1045                 if ( $ns === self::NS_RDF && $tag === 'Description' ) {
1046                         $this->doAttribs( $attribs );
1047                         array_unshift( $this->mode, self::MODE_STRUCT );
1048                         array_unshift( $this->curItem, $this->curItem[0] );
1049                 }
1050         }
1051
1052         /**
1053          * opening element in MODE_LI
1054          * process elements of arrays.
1055          *
1056          * Example:
1057          * <exif:ISOSpeedRatings> <rdf:Seq> <rdf:li>64</rdf:li>
1058          *   </rdf:Seq> </exif:ISOSpeedRatings>
1059          * This method is called when we hit the <rdf:li> element.
1060          *
1061          * @param string $elm Namespace . ' ' . tagname
1062          * @param array $attribs Attributes. (needed for BAGSTRUCTS)
1063          * @throws MWException If gets a tag other than <rdf:li>
1064          */
1065         private function startElementModeLi( $elm, $attribs ) {
1066                 if ( ( $elm ) !== self::NS_RDF . ' li' ) {
1067                         throw new MWException( "<rdf:li> expected but got $elm." );
1068                 }
1069
1070                 if ( !isset( $this->mode[1] ) ) {
1071                         // This should never ever ever happen. Checking for it
1072                         // to be paranoid.
1073                         throw new MWException( 'In mode Li, but no 2xPrevious mode!' );
1074                 }
1075
1076                 if ( $this->mode[1] === self::MODE_BAGSTRUCT ) {
1077                         // This list item contains a compound (STRUCT) value.
1078                         array_unshift( $this->mode, self::MODE_STRUCT );
1079                         array_unshift( $this->curItem, $elm );
1080                         $this->processingArray = true;
1081
1082                         if ( !isset( $this->curItem[1] ) ) {
1083                                 // be paranoid.
1084                                 throw new MWException( 'Can not find parent of BAGSTRUCT.' );
1085                         }
1086                         list( $curNS, $curTag ) = explode( ' ', $this->curItem[1] );
1087                         $this->ancestorStruct = isset( $this->items[$curNS][$curTag]['map_name'] )
1088                                 ? $this->items[$curNS][$curTag]['map_name'] : $curTag;
1089
1090                         $this->doAttribs( $attribs );
1091                 } else {
1092                         // Normal BAG or SEQ containing simple values.
1093                         array_unshift( $this->mode, self::MODE_SIMPLE );
1094                         // need to add curItem[0] on again since one is for the specific item
1095                         // and one is for the entire group.
1096                         array_unshift( $this->curItem, $this->curItem[0] );
1097                         $this->processingArray = true;
1098                 }
1099         }
1100
1101         /**
1102          * Opening element in MODE_LI_LANG.
1103          * process elements of language alternatives
1104          *
1105          * Example:
1106          * <dc:title> <rdf:Alt> <rdf:li xml:lang="x-default">My house
1107          *  </rdf:li> </rdf:Alt> </dc:title>
1108          *
1109          * This method is called when we hit the <rdf:li> element.
1110          *
1111          * @param string $elm Namespace . ' ' . tag
1112          * @param array $attribs Array of elements (most importantly xml:lang)
1113          * @throws MWException If gets a tag other than <rdf:li> or if no xml:lang
1114          */
1115         private function startElementModeLiLang( $elm, $attribs ) {
1116                 if ( $elm !== self::NS_RDF . ' li' ) {
1117                         throw new MWException( __METHOD__ . " <rdf:li> expected but got $elm." );
1118                 }
1119                 if ( !isset( $attribs[self::NS_XML . ' lang'] )
1120                         || !preg_match( '/^[-A-Za-z0-9]{2,}$/D', $attribs[self::NS_XML . ' lang'] )
1121                 ) {
1122                         throw new MWException( __METHOD__
1123                                 . " <rdf:li> did not contain, or has invalid xml:lang attribute in lang alternative" );
1124                 }
1125
1126                 // Lang is case-insensitive.
1127                 $this->itemLang = strtolower( $attribs[self::NS_XML . ' lang'] );
1128
1129                 // need to add curItem[0] on again since one is for the specific item
1130                 // and one is for the entire group.
1131                 array_unshift( $this->curItem, $this->curItem[0] );
1132                 array_unshift( $this->mode, self::MODE_SIMPLE );
1133                 $this->processingArray = true;
1134         }
1135
1136         /**
1137          * Hits an opening element.
1138          * Generally just calls a helper based on what MODE we're in.
1139          * Also does some initial set up for the wrapper element
1140          *
1141          * @param XMLParser $parser
1142          * @param string $elm Namespace "<space>" element
1143          * @param array $attribs Attribute name => value
1144          * @throws MWException
1145          */
1146         function startElement( $parser, $elm, $attribs ) {
1147
1148                 if ( $elm === self::NS_RDF . ' RDF'
1149                         || $elm === 'adobe:ns:meta/ xmpmeta'
1150                         || $elm === 'adobe:ns:meta/ xapmeta'
1151                 ) {
1152                         /* ignore. */
1153                         return;
1154                 } elseif ( $elm === self::NS_RDF . ' Description' ) {
1155                         if ( count( $this->mode ) === 0 ) {
1156                                 // outer rdf:desc
1157                                 array_unshift( $this->mode, self::MODE_INITIAL );
1158                         }
1159                 } elseif ( $elm === self::NS_RDF . ' type' ) {
1160                         // This doesn't support rdf:type properly.
1161                         // In practise I have yet to see a file that
1162                         // uses this element, however it is mentioned
1163                         // on page 25 of part 1 of the xmp standard.
1164                         //
1165                         // also it seems as if exiv2 and exiftool do not support
1166                         // this either (That or I misunderstand the standard)
1167                         wfDebugLog( 'XMP', __METHOD__ . ' Encountered <rdf:type> which isn\'t currently supported' );
1168                 }
1169
1170                 if ( strpos( $elm, ' ' ) === false ) {
1171                         // This probably shouldn't happen.
1172                         wfDebugLog( 'XMP', __METHOD__ . " Encountered <$elm> which has no namespace. Skipping." );
1173
1174                         return;
1175                 }
1176
1177                 list( $ns, $tag ) = explode( ' ', $elm, 2 );
1178
1179                 if ( count( $this->mode ) === 0 ) {
1180                         // This should not happen.
1181                         throw new MWException( 'Error extracting XMP, '
1182                                 . "encountered <$elm> with no mode" );
1183                 }
1184
1185                 switch ( $this->mode[0] ) {
1186                         case self::MODE_IGNORE:
1187                                 $this->startElementModeIgnore( $elm );
1188                                 break;
1189                         case self::MODE_SIMPLE:
1190                                 $this->startElementModeSimple( $elm, $attribs );
1191                                 break;
1192                         case self::MODE_INITIAL:
1193                                 $this->startElementModeInitial( $ns, $tag, $attribs );
1194                                 break;
1195                         case self::MODE_STRUCT:
1196                                 $this->startElementModeStruct( $ns, $tag, $attribs );
1197                                 break;
1198                         case self::MODE_BAG:
1199                         case self::MODE_BAGSTRUCT:
1200                                 $this->startElementModeBag( $elm );
1201                                 break;
1202                         case self::MODE_SEQ:
1203                                 $this->startElementModeSeq( $elm );
1204                                 break;
1205                         case self::MODE_LANG:
1206                                 $this->startElementModeLang( $elm );
1207                                 break;
1208                         case self::MODE_LI_LANG:
1209                                 $this->startElementModeLiLang( $elm, $attribs );
1210                                 break;
1211                         case self::MODE_LI:
1212                                 $this->startElementModeLi( $elm, $attribs );
1213                                 break;
1214                         case self::MODE_QDESC:
1215                                 $this->startElementModeQDesc( $elm );
1216                                 break;
1217                         default:
1218                                 throw new MWException( 'StartElement in unknown mode: ' . $this->mode[0] );
1219                 }
1220         }
1221
1222         /**
1223          * Process attributes.
1224          * Simple values can be stored as either a tag or attribute
1225          *
1226          * Often the initial "<rdf:Description>" tag just has all the simple
1227          * properties as attributes.
1228          *
1229          * @codingStandardsIgnoreStart Long line that cannot be broken
1230          * @par Example:
1231          * @code
1232          * <rdf:Description rdf:about="" xmlns:exif="http://ns.adobe.com/exif/1.0/" exif:DigitalZoomRatio="0/10">
1233          * @endcode
1234          * @codingStandardsIgnoreEnd
1235          *
1236          * @param array $attribs Array attribute=>value
1237          * @throws MWException
1238          */
1239         private function doAttribs( $attribs ) {
1240                 // first check for rdf:parseType attribute, as that can change
1241                 // how the attributes are interperted.
1242
1243                 if ( isset( $attribs[self::NS_RDF . ' parseType'] )
1244                         && $attribs[self::NS_RDF . ' parseType'] === 'Resource'
1245                         && $this->mode[0] === self::MODE_SIMPLE
1246                 ) {
1247                         // this is equivalent to having an inner rdf:Description
1248                         $this->mode[0] = self::MODE_QDESC;
1249                 }
1250                 foreach ( $attribs as $name => $val ) {
1251                         if ( strpos( $name, ' ' ) === false ) {
1252                                 // This shouldn't happen, but so far some old software forgets namespace
1253                                 // on rdf:about.
1254                                 wfDebugLog( 'XMP', __METHOD__ . ' Encountered non-namespaced attribute: '
1255                                         . " $name=\"$val\". Skipping. " );
1256                                 continue;
1257                         }
1258                         list( $ns, $tag ) = explode( ' ', $name, 2 );
1259                         if ( $ns === self::NS_RDF ) {
1260                                 if ( $tag === 'value' || $tag === 'resource' ) {
1261                                         // resource is for url.
1262                                         // value attribute is a weird way of just putting the contents.
1263                                         $this->char( $this->xmlParser, $val );
1264                                 }
1265                         } elseif ( isset( $this->items[$ns][$tag] ) ) {
1266                                 if ( $this->mode[0] === self::MODE_SIMPLE ) {
1267                                         throw new MWException( __METHOD__
1268                                                 . " $ns:$tag found as attribute where not allowed" );
1269                                 }
1270                                 $this->saveValue( $ns, $tag, $val );
1271                         } else {
1272                                 wfDebugLog( 'XMP', __METHOD__ . " Ignoring unrecognized element <$ns:$tag>." );
1273                         }
1274                 }
1275         }
1276
1277         /**
1278          * Given an extracted value, save it to results array
1279          *
1280          * note also uses $this->ancestorStruct and
1281          * $this->processingArray to determine what name to
1282          * save the value under. (in addition to $tag).
1283          *
1284          * @param string $ns Namespace of tag this is for
1285          * @param string $tag Tag name
1286          * @param string $val Value to save
1287          */
1288         private function saveValue( $ns, $tag, $val ) {
1289
1290                 $info =& $this->items[$ns][$tag];
1291                 $finalName = isset( $info['map_name'] )
1292                         ? $info['map_name'] : $tag;
1293                 if ( isset( $info['validate'] ) ) {
1294                         $validate = is_array( $info['validate'] ) ? $info['validate']
1295                                 : array( 'XMPValidate', $info['validate'] );
1296
1297                         if ( is_callable( $validate ) ) {
1298                                 call_user_func_array( $validate, array( $info, &$val, true ) );
1299                                 // the reasoning behind using &$val instead of using the return value
1300                                 // is to be consistent between here and validating structures.
1301                                 if ( is_null( $val ) ) {
1302                                         wfDebugLog( 'XMP', __METHOD__ . " <$ns:$tag> failed validation." );
1303
1304                                         return;
1305                                 }
1306                         } else {
1307                                 wfDebugLog( 'XMP', __METHOD__ . " Validation function for $finalName ("
1308                                         . $validate[0] . '::' . $validate[1] . '()) is not callable.' );
1309                         }
1310                 }
1311
1312                 if ( $this->ancestorStruct && $this->processingArray ) {
1313                         // Aka both an array and a struct. ( self::MODE_BAGSTRUCT )
1314                         $this->results['xmp-' . $info['map_group']][$this->ancestorStruct][][$finalName] = $val;
1315                 } elseif ( $this->ancestorStruct ) {
1316                         $this->results['xmp-' . $info['map_group']][$this->ancestorStruct][$finalName] = $val;
1317                 } elseif ( $this->processingArray ) {
1318                         if ( $this->itemLang === false ) {
1319                                 // normal array
1320                                 $this->results['xmp-' . $info['map_group']][$finalName][] = $val;
1321                         } else {
1322                                 // lang array.
1323                                 $this->results['xmp-' . $info['map_group']][$finalName][$this->itemLang] = $val;
1324                         }
1325                 } else {
1326                         $this->results['xmp-' . $info['map_group']][$finalName] = $val;
1327                 }
1328         }
1329 }