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 use Psr\Log\LoggerAwareInterface;
  25 use Psr\Log\LoggerInterface;
  26 use Psr\Log\NullLogger;
  27
  28 /**
  29  * Class for reading xmp data containing properties relevant to
  30  * images, and spitting out an array that FormatMetadata accepts.
  31  *
  32  * Note, this is not meant to recognize every possible thing you can
  33  * encode in XMP. It should recognize all the properties we want.
  34  * For example it doesn't have support for structures with multiple
  35  * nesting levels, as none of the properties we're supporting use that
  36  * feature. If it comes across properties it doesn't recognize, it should
  37  * ignore them.
  38  *
  39  * The public methods one would call in this class are
  40  * - parse( $content )
  41  *    Reads in xmp content.
  42  *    Can potentially be called multiple times with partial data each time.
  43  * - parseExtended( $content )
  44  *    Reads XMPExtended blocks (jpeg files only).
  45  * - getResults
  46  *    Outputs a results array.
  47  *
  48  * Note XMP kind of looks like rdf. They are not the same thing - XMP is
  49  * encoded as a specific subset of rdf. This class can read XMP. It cannot
  50  * read rdf.
  51  *
  52  */
  53 class XMPReader implements LoggerAwareInterface {
  54         /** @var array XMP item configuration array */
  55         protected $items;
  56
  57         /** @var array Array to hold the current element (and previous element, and so on) */
  58         private $curItem = array();
  59
  60         /** @var bool|string The structure name when processing nested structures. */
  61         private $ancestorStruct = false;
  62
  63         /** @var bool|string Temporary holder for character data that appears in xmp doc. */
  64         private $charContent = false;
  65
  66         /** @var array Stores the state the xmpreader is in (see MODE_FOO constants) */
  67         private $mode = array();
  68
  69         /** @var array Array to hold results */
  70         private $results = array();
  71
  72         /** @var bool If we're doing a seq or bag. */
  73         private $processingArray = false;
  74
  75         /** @var bool|string Used for lang alts only */
  76         private $itemLang = false;
  77
  78         /** @var resource A resource handle for the XML parser */
  79         private $xmlParser;
  80
  81         /** @var bool|string Character set like 'UTF-8' */
  82         private $charset = false;
  83
  84         /** @var int */
  85         private $extendedXMPOffset = 0;
  86
  87         /** @var int Flag determining if the XMP is safe to parse **/
  88         private $parsable = 0;
  89
  90         /** @var string Buffer of XML to parse **/
  91         private $xmlParsableBuffer = '';
  92
  93         /**
  94          * These are various mode constants.
  95          * they are used to figure out what to do
  96          * with an element when its encountered.
  97          *
  98          * For example, MODE_IGNORE is used when processing
  99          * a property we're not interested in. So if a new
 100          * element pops up when we're in that mode, we ignore it.
 101          */
 102         const MODE_INITIAL = 0;
 103         const MODE_IGNORE = 1;
 104         const MODE_LI = 2;
 105         const MODE_LI_LANG = 3;
 106         const MODE_QDESC = 4;
 107
 108         // The following MODE constants are also used in the
 109         // $items array to denote what type of property the item is.
 110         const MODE_SIMPLE = 10;
 111         const MODE_STRUCT = 11; // structure (associative array)
 112         const MODE_SEQ = 12; // ordered list
 113         const MODE_BAG = 13; // unordered list
 114         const MODE_LANG = 14;
 115         const MODE_ALT = 15; // non-language alt. Currently not implemented, and not needed atm.
 116         const MODE_BAGSTRUCT = 16; // A BAG of Structs.
 117
 118         const NS_RDF = 'http://www.w3.org/1999/02/22-rdf-syntax-ns#';
 119         const NS_XML = 'http://www.w3.org/XML/1998/namespace';
 120
 121         // States used while determining if XML is safe to parse
 122         const PARSABLE_UNKNOWN = 0;
 123         const PARSABLE_OK = 1;
 124         const PARSABLE_BUFFERING = 2;
 125         const PARSABLE_NO = 3;
 126
 127         /**
 128          * @var LoggerInterface
 129          */
 130         private $logger;
 131
 132         /**
 133          * Constructor.
 134          *
 135          * Primary job is to initialize the XMLParser
 136          */
 137         function __construct( LoggerInterface $logger = null ) {
 138
 139                 if ( !function_exists( 'xml_parser_create_ns' ) ) {
 140                         // this should already be checked by this point
 141                         throw new RuntimeException( 'XMP support requires XML Parser' );
 142                 }
 143                 if ( $logger ) {
 144                         $this->setLogger( $logger );
 145                 } else {
 146                         $this->setLogger( new NullLogger() );
 147                 }
 148
 149                 $this->items = XMPInfo::getItems();
 150
 151                 $this->resetXMLParser();
 152         }
 153
 154         public function setLogger( LoggerInterface $logger ) {
 155                 $this->logger = $logger;
 156         }
 157
 158         /**
 159          * free the XML parser.
 160          *
 161          * @note It is unclear to me if we really need to do this ourselves
 162          *  or if php garbage collection will automatically free the xmlParser
 163          *  when it is no longer needed.
 164          */
 165         private function destroyXMLParser() {
 166                 if ( $this->xmlParser ) {
 167                         xml_parser_free( $this->xmlParser );
 168                         $this->xmlParser = null;
 169                 }
 170         }
 171
 172         /**
 173          * Main use is if a single item has multiple xmp documents describing it.
 174          * For example in jpeg's with extendedXMP
 175          */
 176         private function resetXMLParser() {
 177
 178                 $this->destroyXMLParser();
 179
 180                 $this->xmlParser = xml_parser_create_ns( 'UTF-8', ' ' );
 181                 xml_parser_set_option( $this->xmlParser, XML_OPTION_CASE_FOLDING, 0 );
 182                 xml_parser_set_option( $this->xmlParser, XML_OPTION_SKIP_WHITE, 1 );
 183
 184                 xml_set_element_handler( $this->xmlParser,
 185                         array( $this, 'startElement' ),
 186                         array( $this, 'endElement' ) );
 187
 188                 xml_set_character_data_handler( $this->xmlParser, array( $this, 'char' ) );
 189
 190                 $this->parsable = self::PARSABLE_UNKNOWN;
 191                 $this->xmlParsableBuffer = '';
 192         }
 193
 194         /**
 195          * Check if this instance supports using this class
 196          */
 197         public static function isSupported() {
 198                 return function_exists( 'xml_parser_create_ns' ) && class_exists( 'XMLReader' );
 199         }
 200
 201         /** Get the result array. Do some post-processing before returning
 202          * the array, and transform any metadata that is special-cased.
 203          *
 204          * @return array Array of results as an array of arrays suitable for
 205          *    FormatMetadata::getFormattedData().
 206          */
 207         public function getResults() {
 208                 // xmp-special is for metadata that affects how stuff
 209                 // is extracted. For example xmpNote:HasExtendedXMP.
 210
 211                 // It is also used to handle photoshop:AuthorsPosition
 212                 // which is weird and really part of another property,
 213                 // see 2:85 in IPTC. See also pg 21 of IPTC4XMP standard.
 214                 // The location fields also use it.
 215
 216                 $data = $this->results;
 217
 218                 if ( isset( $data['xmp-special']['AuthorsPosition'] )
 219                         && is_string( $data['xmp-special']['AuthorsPosition'] )
 220                         && isset( $data['xmp-general']['Artist'][0] )
 221                 ) {
 222                         // Note, if there is more than one creator,
 223                         // this only applies to first. This also will
 224                         // only apply to the dc:Creator prop, not the
 225                         // exif:Artist prop.
 226
 227                         $data['xmp-general']['Artist'][0] =
 228                                 $data['xmp-special']['AuthorsPosition'] . ', '
 229                                 . $data['xmp-general']['Artist'][0];
 230                 }
 231
 232                 // Go through the LocationShown and LocationCreated
 233                 // changing it to the non-hierarchal form used by
 234                 // the other location fields.
 235
 236                 if ( isset( $data['xmp-special']['LocationShown'][0] )
 237                         && is_array( $data['xmp-special']['LocationShown'][0] )
 238                 ) {
 239                         // the is_array is just paranoia. It should always
 240                         // be an array.
 241                         foreach ( $data['xmp-special']['LocationShown'] as $loc ) {
 242                                 if ( !is_array( $loc ) ) {
 243                                         // To avoid copying over the _type meta-fields.
 244                                         continue;
 245                                 }
 246                                 foreach ( $loc as $field => $val ) {
 247                                         $data['xmp-general'][$field . 'Dest'][] = $val;
 248                                 }
 249                         }
 250                 }
 251                 if ( isset( $data['xmp-special']['LocationCreated'][0] )
 252                         && is_array( $data['xmp-special']['LocationCreated'][0] )
 253                 ) {
 254                         // the is_array is just paranoia. It should always
 255                         // be an array.
 256                         foreach ( $data['xmp-special']['LocationCreated'] as $loc ) {
 257                                 if ( !is_array( $loc ) ) {
 258                                         // To avoid copying over the _type meta-fields.
 259                                         continue;
 260                                 }
 261                                 foreach ( $loc as $field => $val ) {
 262                                         $data['xmp-general'][$field . 'Created'][] = $val;
 263                                 }
 264                         }
 265                 }
 266
 267                 // We don't want to return the special values, since they're
 268                 // special and not info to be stored about the file.
 269                 unset( $data['xmp-special'] );
 270
 271                 // Convert GPSAltitude to negative if below sea level.
 272                 if ( isset( $data['xmp-exif']['GPSAltitudeRef'] )
 273                         && isset( $data['xmp-exif']['GPSAltitude'] )
 274                 ) {
 275
 276                         // Must convert to a real before multiplying by -1
 277                         // XMPValidate guarantees there will always be a '/' in this value.
 278                         list( $nom, $denom ) = explode( '/', $data['xmp-exif']['GPSAltitude'] );
 279                         $data['xmp-exif']['GPSAltitude'] = $nom / $denom;
 280
 281                         if ( $data['xmp-exif']['GPSAltitudeRef'] == '1' ) {
 282                                 $data['xmp-exif']['GPSAltitude'] *= -1;
 283                         }
 284                         unset( $data['xmp-exif']['GPSAltitudeRef'] );
 285                 }
 286
 287                 return $data;
 288         }
 289
 290         /**
 291          * Main function to call to parse XMP. Use getResults to
 292          * get results.
 293          *
 294          * Also catches any errors during processing, writes them to
 295          * debug log, blanks result array and returns false.
 296          *
 297          * @param string $content XMP data
 298          * @param bool $allOfIt If this is all the data (true) or if its split up (false). Default true
 299          * @throws RuntimeException
 300          * @return bool Success.
 301          */
 302         public function parse( $content, $allOfIt = true ) {
 303                 if ( !$this->xmlParser ) {
 304                         $this->resetXMLParser();
 305                 }
 306                 try {
 307
 308                         // detect encoding by looking for BOM which is supposed to be in processing instruction.
 309                         // see page 12 of http://www.adobe.com/devnet/xmp/pdfs/XMPSpecificationPart3.pdf
 310                         if ( !$this->charset ) {
 311                                 $bom = array();
 312                                 if ( preg_match( '/\xEF\xBB\xBF|\xFE\xFF|\x00\x00\xFE\xFF|\xFF\xFE\x00\x00|\xFF\xFE/',
 313                                         $content, $bom )
 314                                 ) {
 315                                         switch ( $bom[0] ) {
 316                                                 case "\xFE\xFF":
 317                                                         $this->charset = 'UTF-16BE';
 318                                                         break;
 319                                                 case "\xFF\xFE":
 320                                                         $this->charset = 'UTF-16LE';
 321                                                         break;
 322                                                 case "\x00\x00\xFE\xFF":
 323                                                         $this->charset = 'UTF-32BE';
 324                                                         break;
 325                                                 case "\xFF\xFE\x00\x00":
 326                                                         $this->charset = 'UTF-32LE';
 327                                                         break;
 328                                                 case "\xEF\xBB\xBF":
 329                                                         $this->charset = 'UTF-8';
 330                                                         break;
 331                                                 default:
 332                                                         //this should be impossible to get to
 333                                                         throw new RuntimeException( "Invalid BOM" );
 334                                         }
 335                                 } else {
 336                                         // standard specifically says, if no bom assume utf-8
 337                                         $this->charset = 'UTF-8';
 338                                 }
 339                         }
 340                         if ( $this->charset !== 'UTF-8' ) {
 341                                 //don't convert if already utf-8
 342                                 MediaWiki\suppressWarnings();
 343                                 $content = iconv( $this->charset, 'UTF-8//IGNORE', $content );
 344                                 MediaWiki\restoreWarnings();
 345                         }
 346
 347                         // Ensure the XMP block does not have an xml doctype declaration, which
 348                         // could declare entities unsafe to parse with xml_parse (T85848/T71210).
 349                         if ( $this->parsable !== self::PARSABLE_OK ) {
 350                                 if ( $this->parsable === self::PARSABLE_NO ) {
 351                                         throw new RuntimeException( 'Unsafe doctype declaration in XML.' );
 352                                 }
 353
 354                                 $content = $this->xmlParsableBuffer . $content;
 355                                 if ( !$this->checkParseSafety( $content ) ) {
 356                                         if ( !$allOfIt && $this->parsable !== self::PARSABLE_NO ) {
 357                                                 // parse wasn't Unsuccessful yet, so return true
 358                                                 // in this case.
 359                                                 return true;
 360                                         }
 361                                         $msg = ( $this->parsable === self::PARSABLE_NO ) ?
 362                                                 'Unsafe doctype declaration in XML.' :
 363                                                 'No root element found in XML.';
 364                                         throw new RuntimeException( $msg );
 365                                 }
 366                         }
 367
 368                         $ok = xml_parse( $this->xmlParser, $content, $allOfIt );
 369                         if ( !$ok ) {
 370                                 $code = xml_get_error_code( $this->xmlParser );
 371                                 $error = xml_error_string( $code );
 372                                 $line = xml_get_current_line_number( $this->xmlParser );
 373                                 $col = xml_get_current_column_number( $this->xmlParser );
 374                                 $offset = xml_get_current_byte_index( $this->xmlParser );
 375
 376                                 $this->logger->warning(
 377                                         '{method} : Error reading XMP content: {error} ' .
 378                                         '(line: {line} column: {column} byte offset: {offset})',
 379                                         array(
 380                                                 'method' => __METHOD__,
 381                                                 'error_code' => $code,
 382                                                 'error' => $error,
 383                                                 'line' => $line,
 384                                                 'column' => $col,
 385                                                 'offset' => $offset,
 386                                                 'content' => $content,
 387                                 ) );
 388                                 $this->results = array(); // blank if error.
 389                                 $this->destroyXMLParser();
 390                                 return false;
 391                         }
 392                 } catch ( Exception $e ) {
 393                         $this->logger->warning(
 394                                 '{method} Exception caught while parsing: ' . $e->getMessage(),
 395                                 array(
 396                                         'method' => __METHOD__,
 397                                         'exception' => $e,
 398                                         'content' => $content,
 399                                 )
 400                         );
 401                         $this->results = array();
 402
 403                         if ( $allOfIt ) {
 404                                 $this->destroyXMLParser();
 405                         }
 406                         return false;
 407                 }
 408                 if ( $allOfIt ) {
 409                         $this->destroyXMLParser();
 410                 }
 411
 412                 return true;
 413         }
 414
 415         /** Entry point for XMPExtended blocks in jpeg files
 416          *
 417          * @todo In serious need of testing
 418          * @see http://www.adobe.ge/devnet/xmp/pdfs/XMPSpecificationPart3.pdf XMP spec part 3 page 20
 419          * @param string $content XMPExtended block minus the namespace signature
 420          * @return bool If it succeeded.
 421          */
 422         public function parseExtended( $content ) {
 423                 // @todo FIXME: This is untested. Hard to find example files
 424                 // or programs that make such files..
 425                 $guid = substr( $content, 0, 32 );
 426                 if ( !isset( $this->results['xmp-special']['HasExtendedXMP'] )
 427                         || $this->results['xmp-special']['HasExtendedXMP'] !== $guid
 428                 ) {
 429                         $this->logger->info( __METHOD__ .
 430                                 " Ignoring XMPExtended block due to wrong guid (guid= '$guid')" );
 431
 432                         return false;
 433                 }
 434                 $len = unpack( 'Nlength/Noffset', substr( $content, 32, 8 ) );
 435
 436                 if ( !$len || $len['length'] < 4 || $len['offset'] < 0 || $len['offset'] > $len['length'] ) {
 437                         $this->logger->info( __METHOD__ . 'Error reading extended XMP block, invalid length or offset.' );
 438
 439                         return false;
 440                 }
 441
 442                 // we're not very robust here. we should accept it in the wrong order.
 443                 // To quote the XMP standard:
 444                 // "A JPEG writer should write the ExtendedXMP marker segments in order,
 445                 // immediately following the StandardXMP. However, the JPEG standard
 446                 // does not require preservation of marker segment order. A robust JPEG
 447                 // reader should tolerate the marker segments in any order."
 448                 //
 449                 // otoh the probability that an image will have more than 128k of
 450                 // metadata is rather low... so the probability that it will have
 451                 // > 128k, and be in the wrong order is very low...
 452
 453                 if ( $len['offset'] !== $this->extendedXMPOffset ) {
 454                         $this->logger->info( __METHOD__ . 'Ignoring XMPExtended block due to wrong order. (Offset was '
 455                                 . $len['offset'] . ' but expected ' . $this->extendedXMPOffset . ')' );
 456
 457                         return false;
 458                 }
 459
 460                 if ( $len['offset'] === 0 ) {
 461                         // if we're starting the extended block, we've probably already
 462                         // done the XMPStandard block, so reset.
 463                         $this->resetXMLParser();
 464                 }
 465
 466                 $this->extendedXMPOffset += $len['length'];
 467
 468                 $actualContent = substr( $content, 40 );
 469
 470                 if ( $this->extendedXMPOffset === strlen( $actualContent ) ) {
 471                         $atEnd = true;
 472                 } else {
 473                         $atEnd = false;
 474                 }
 475
 476                 $this->logger->debug( __METHOD__ . 'Parsing a XMPExtended block' );
 477
 478                 return $this->parse( $actualContent, $atEnd );
 479         }
 480
 481         /**
 482          * Character data handler
 483          * Called whenever character data is found in the xmp document.
 484          *
 485          * does nothing if we're in MODE_IGNORE or if the data is whitespace
 486          * throws an error if we're not in MODE_SIMPLE (as we're not allowed to have character
 487          * data in the other modes).
 488          *
 489          * As an example, this happens when we encounter XMP like:
 490          * <exif:DigitalZoomRatio>0/10</exif:DigitalZoomRatio>
 491          * and are processing the 0/10 bit.
 492          *
 493          * @param XMLParser $parser XMLParser reference to the xml parser
 494          * @param string $data Character data
 495          * @throws RuntimeException On invalid data
 496          */
 497         function char( $parser, $data ) {
 498
 499                 $data = trim( $data );
 500                 if ( trim( $data ) === "" ) {
 501                         return;
 502                 }
 503
 504                 if ( !isset( $this->mode[0] ) ) {
 505                         throw new RuntimeException( 'Unexpected character data before first rdf:Description element' );
 506                 }
 507
 508                 if ( $this->mode[0] === self::MODE_IGNORE ) {
 509                         return;
 510                 }
 511
 512                 if ( $this->mode[0] !== self::MODE_SIMPLE
 513                         && $this->mode[0] !== self::MODE_QDESC
 514                 ) {
 515                         throw new RuntimeException( 'character data where not expected. (mode ' . $this->mode[0] . ')' );
 516                 }
 517
 518                 // to check, how does this handle w.s.
 519                 if ( $this->charContent === false ) {
 520                         $this->charContent = $data;
 521                 } else {
 522                         $this->charContent .= $data;
 523                 }
 524         }
 525
 526         /**
 527          * Check if a block of XML is safe to pass to xml_parse, i.e. doesn't
 528          * contain a doctype declaration which could contain a dos attack if we
 529          * parse it and expand internal entities (T85848).
 530          *
 531          * @param string $content xml string to check for parse safety
 532          * @return bool true if the xml is safe to parse, false otherwise
 533          */
 534         private function checkParseSafety( $content ) {
 535                 $reader = new XMLReader();
 536                 $result = null;
 537
 538                 // For XMLReader to parse incomplete/invalid XML, it has to be open()'ed
 539                 // instead of using XML().
 540                 $reader->open(
 541                         'data://text/plain,' . urlencode( $content ),
 542                         null,
 543                         LIBXML_NOERROR | LIBXML_NOWARNING | LIBXML_NONET
 544                 );
 545
 546                 $oldDisable = libxml_disable_entity_loader( true );
 547                 /** @noinspection PhpUnusedLocalVariableInspection */
 548                 $reset = new ScopedCallback(
 549                         'libxml_disable_entity_loader',
 550                         array( $oldDisable )
 551                 );
 552                 $reader->setParserProperty( XMLReader::SUBST_ENTITIES, false );
 553
 554                 // Even with LIBXML_NOWARNING set, XMLReader::read gives a warning
 555                 // when parsing truncated XML, which causes unit tests to fail.
 556                 MediaWiki\suppressWarnings();
 557                 while ( $reader->read() ) {
 558                         if ( $reader->nodeType === XMLReader::ELEMENT ) {
 559                                 // Reached the first element without hitting a doctype declaration
 560                                 $this->parsable = self::PARSABLE_OK;
 561                                 $result = true;
 562                                 break;
 563                         }
 564                         if ( $reader->nodeType === XMLReader::DOC_TYPE ) {
 565                                 $this->parsable = self::PARSABLE_NO;
 566                                 $result = false;
 567                                 break;
 568                         }
 569                 }
 570                 MediaWiki\restoreWarnings();
 571
 572                 if ( !is_null( $result ) ) {
 573                         return $result;
 574                 }
 575
 576                 // Reached the end of the parsable xml without finding an element
 577                 // or doctype. Buffer and try again.
 578                 $this->parsable = self::PARSABLE_BUFFERING;
 579                 $this->xmlParsableBuffer = $content;
 580                 return false;
 581         }
 582
 583         /** When we hit a closing element in MODE_IGNORE
 584          * Check to see if this is the element we started to ignore,
 585          * in which case we get out of MODE_IGNORE
 586          *
 587          * @param string $elm Namespace of element followed by a space and then tag name of element.
 588          */
 589         private function endElementModeIgnore( $elm ) {
 590                 if ( $this->curItem[0] === $elm ) {
 591                         array_shift( $this->curItem );
 592                         array_shift( $this->mode );
 593                 }
 594         }
 595
 596         /**
 597          * Hit a closing element when in MODE_SIMPLE.
 598          * This generally means that we finished processing a
 599          * property value, and now have to save the result to the
 600          * results array
 601          *
 602          * For example, when processing:
 603          * <exif:DigitalZoomRatio>0/10</exif:DigitalZoomRatio>
 604          * this deals with when we hit </exif:DigitalZoomRatio>.
 605          *
 606          * Or it could be if we hit the end element of a property
 607          * of a compound data structure (like a member of an array).
 608          *
 609          * @param string $elm Namespace, space, and tag name.
 610          */
 611         private function endElementModeSimple( $elm ) {
 612                 if ( $this->charContent !== false ) {
 613                         if ( $this->processingArray ) {
 614                                 // if we're processing an array, use the original element
 615                                 // name instead of rdf:li.
 616                                 list( $ns, $tag ) = explode( ' ', $this->curItem[0], 2 );
 617                         } else {
 618                                 list( $ns, $tag ) = explode( ' ', $elm, 2 );
 619                         }
 620                         $this->saveValue( $ns, $tag, $this->charContent );
 621
 622                         $this->charContent = false; // reset
 623                 }
 624                 array_shift( $this->curItem );
 625                 array_shift( $this->mode );
 626         }
 627
 628         /**
 629          * Hit a closing element in MODE_STRUCT, MODE_SEQ, MODE_BAG
 630          * generally means we've finished processing a nested structure.
 631          * resets some internal variables to indicate that.
 632          *
 633          * Note this means we hit the closing element not the "</rdf:Seq>".
 634          *
 635          * @par For example, when processing:
 636          * @code{,xml}
 637          * <exif:ISOSpeedRatings> <rdf:Seq> <rdf:li>64</rdf:li>
 638          *   </rdf:Seq> </exif:ISOSpeedRatings>
 639          * @endcode
 640          *
 641          * This method is called when we hit the "</exif:ISOSpeedRatings>" tag.
 642          *
 643          * @param string $elm Namespace . space . tag name.
 644          * @throws RuntimeException
 645          */
 646         private function endElementNested( $elm ) {
 647
 648                 /* cur item must be the same as $elm, unless if in MODE_STRUCT
 649                    in which case it could also be rdf:Description */
 650                 if ( $this->curItem[0] !== $elm
 651                         && !( $elm === self::NS_RDF . ' Description'
 652                                 && $this->mode[0] === self::MODE_STRUCT )
 653                 ) {
 654                         throw new RuntimeException( "nesting mismatch. got a </$elm> but expected a </" .
 655                                 $this->curItem[0] . '>' );
 656                 }
 657
 658                 // Validate structures.
 659                 list( $ns, $tag ) = explode( ' ', $elm, 2 );
 660                 if ( isset( $this->items[$ns][$tag]['validate'] ) ) {
 661                         $info =& $this->items[$ns][$tag];
 662                         $finalName = isset( $info['map_name'] )
 663                                 ? $info['map_name'] : $tag;
 664
 665                         if ( is_array( $info['validate'] ) ) {
 666                                 $validate = $info['validate'];
 667                         } else {
 668                                 $validator = new XMPValidate( $this->logger );
 669                                 $validate = array( $validator, $info['validate'] );
 670                         }
 671
 672                         if ( !isset( $this->results['xmp-' . $info['map_group']][$finalName] ) ) {
 673                                 // This can happen if all the members of the struct failed validation.
 674                                 $this->logger->debug( __METHOD__ . " <$ns:$tag> has no valid members." );
 675                         } elseif ( is_callable( $validate ) ) {
 676                                 $val =& $this->results['xmp-' . $info['map_group']][$finalName];
 677                                 call_user_func_array( $validate, array( $info, &$val, false ) );
 678                                 if ( is_null( $val ) ) {
 679                                         // the idea being the validation function will unset the variable if
 680                                         // its invalid.
 681                                         $this->logger->info( __METHOD__ . " <$ns:$tag> failed validation." );
 682                                         unset( $this->results['xmp-' . $info['map_group']][$finalName] );
 683                                 }
 684                         } else {
 685                                 $this->logger->warning( __METHOD__ . " Validation function for $finalName ("
 686                                         . $validate[0] . '::' . $validate[1] . '()) is not callable.' );
 687                         }
 688                 }
 689
 690                 array_shift( $this->curItem );
 691                 array_shift( $this->mode );
 692                 $this->ancestorStruct = false;
 693                 $this->processingArray = false;
 694                 $this->itemLang = false;
 695         }
 696
 697         /**
 698          * Hit a closing element in MODE_LI (either rdf:Seq, or rdf:Bag )
 699          * Add information about what type of element this is.
 700          *
 701          * Note we still have to hit the outer "</property>"
 702          *
 703          * @par For example, when processing:
 704          * @code{,xml}
 705          * <exif:ISOSpeedRatings> <rdf:Seq> <rdf:li>64</rdf:li>
 706          *   </rdf:Seq> </exif:ISOSpeedRatings>
 707          * @endcode
 708          *
 709          * This method is called when we hit the "</rdf:Seq>".
 710          * (For comparison, we call endElementModeSimple when we
 711          * hit the "</rdf:li>")
 712          *
 713          * @param string $elm Namespace . ' ' . element name
 714          * @throws RuntimeException
 715          */
 716         private function endElementModeLi( $elm ) {
 717
 718                 list( $ns, $tag ) = explode( ' ', $this->curItem[0], 2 );
 719                 $info = $this->items[$ns][$tag];
 720                 $finalName = isset( $info['map_name'] )
 721                         ? $info['map_name'] : $tag;
 722
 723                 array_shift( $this->mode );
 724
 725                 if ( !isset( $this->results['xmp-' . $info['map_group']][$finalName] ) ) {
 726                         $this->logger->debug( __METHOD__ . " Empty compund element $finalName." );
 727
 728                         return;
 729                 }
 730
 731                 if ( $elm === self::NS_RDF . ' Seq' ) {
 732                         $this->results['xmp-' . $info['map_group']][$finalName]['_type'] = 'ol';
 733                 } elseif ( $elm === self::NS_RDF . ' Bag' ) {
 734                         $this->results['xmp-' . $info['map_group']][$finalName]['_type'] = 'ul';
 735                 } elseif ( $elm === self::NS_RDF . ' Alt' ) {
 736                         // extra if needed as you could theoretically have a non-language alt.
 737                         if ( $info['mode'] === self::MODE_LANG ) {
 738                                 $this->results['xmp-' . $info['map_group']][$finalName]['_type'] = 'lang';
 739                         }
 740                 } else {
 741                         throw new RuntimeException( __METHOD__ . " expected </rdf:seq> or </rdf:bag> but instead got $elm." );
 742                 }
 743         }
 744
 745         /**
 746          * End element while in MODE_QDESC
 747          * mostly when ending an element when we have a simple value
 748          * that has qualifiers.
 749          *
 750          * Qualifiers aren't all that common, and we don't do anything
 751          * with them.
 752          *
 753          * @param string $elm Namespace and element
 754          */
 755         private function endElementModeQDesc( $elm ) {
 756
 757                 if ( $elm === self::NS_RDF . ' value' ) {
 758                         list( $ns, $tag ) = explode( ' ', $this->curItem[0], 2 );
 759                         $this->saveValue( $ns, $tag, $this->charContent );
 760
 761                         return;
 762                 } else {
 763                         array_shift( $this->mode );
 764                         array_shift( $this->curItem );
 765                 }
 766         }
 767
 768         /**
 769          * Handler for hitting a closing element.
 770          *
 771          * generally just calls a helper function depending on what
 772          * mode we're in.
 773          *
 774          * Ignores the outer wrapping elements that are optional in
 775          * xmp and have no meaning.
 776          *
 777          * @param XMLParser $parser
 778          * @param string $elm Namespace . ' ' . element name
 779          * @throws RuntimeException
 780          */
 781         function endElement( $parser, $elm ) {
 782                 if ( $elm === ( self::NS_RDF . ' RDF' )
 783                         || $elm === 'adobe:ns:meta/ xmpmeta'
 784                         || $elm === 'adobe:ns:meta/ xapmeta'
 785                 ) {
 786                         // ignore these.
 787                         return;
 788                 }
 789
 790                 if ( $elm === self::NS_RDF . ' type' ) {
 791                         // these aren't really supported properly yet.
 792                         // However, it appears they almost never used.
 793                         $this->logger->info( __METHOD__ . ' encountered <rdf:type>' );
 794                 }
 795
 796                 if ( strpos( $elm, ' ' ) === false ) {
 797                         // This probably shouldn't happen.
 798                         // However, there is a bug in an adobe product
 799                         // that forgets the namespace on some things.
 800                         // (Luckily they are unimportant things).
 801                         $this->logger->info( __METHOD__ . " Encountered </$elm> which has no namespace. Skipping." );
 802
 803                         return;
 804                 }
 805
 806                 if ( count( $this->mode[0] ) === 0 ) {
 807                         // This should never ever happen and means
 808                         // there is a pretty major bug in this class.
 809                         throw new RuntimeException( 'Encountered end element with no mode' );
 810                 }
 811
 812                 if ( count( $this->curItem ) == 0 && $this->mode[0] !== self::MODE_INITIAL ) {
 813                         // just to be paranoid. Should always have a curItem, except for initially
 814                         // (aka during MODE_INITAL).
 815                         throw new RuntimeException( "Hit end element </$elm> but no curItem" );
 816                 }
 817
 818                 switch ( $this->mode[0] ) {
 819                         case self::MODE_IGNORE:
 820                                 $this->endElementModeIgnore( $elm );
 821                                 break;
 822                         case self::MODE_SIMPLE:
 823                                 $this->endElementModeSimple( $elm );
 824                                 break;
 825                         case self::MODE_STRUCT:
 826                         case self::MODE_SEQ:
 827                         case self::MODE_BAG:
 828                         case self::MODE_LANG:
 829                         case self::MODE_BAGSTRUCT:
 830                                 $this->endElementNested( $elm );
 831                                 break;
 832                         case self::MODE_INITIAL:
 833                                 if ( $elm === self::NS_RDF . ' Description' ) {
 834                                         array_shift( $this->mode );
 835                                 } else {
 836                                         throw new RuntimeException( 'Element ended unexpectedly while in MODE_INITIAL' );
 837                                 }
 838                                 break;
 839                         case self::MODE_LI:
 840                         case self::MODE_LI_LANG:
 841                                 $this->endElementModeLi( $elm );
 842                                 break;
 843                         case self::MODE_QDESC:
 844                                 $this->endElementModeQDesc( $elm );
 845                                 break;
 846                         default:
 847                                 $this->logger->warning( __METHOD__ . " no mode (elm = $elm)" );
 848                                 break;
 849                 }
 850         }
 851
 852         /**
 853          * Hit an opening element while in MODE_IGNORE
 854          *
 855          * XMP is extensible, so ignore any tag we don't understand.
 856          *
 857          * Mostly ignores, unless we encounter the element that we are ignoring.
 858          * in which case we add it to the item stack, so we can ignore things
 859          * that are nested, correctly.
 860          *
 861          * @param string $elm Namespace . ' ' . tag name
 862          */
 863         private function startElementModeIgnore( $elm ) {
 864                 if ( $elm === $this->curItem[0] ) {
 865                         array_unshift( $this->curItem, $elm );
 866                         array_unshift( $this->mode, self::MODE_IGNORE );
 867                 }
 868         }
 869
 870         /**
 871          *  Start element in MODE_BAG (unordered array)
 872          * this should always be <rdf:Bag>
 873          *
 874          * @param string $elm Namespace . ' ' . tag
 875          * @throws RuntimeException If we have an element that's not <rdf:Bag>
 876          */
 877         private function startElementModeBag( $elm ) {
 878                 if ( $elm === self::NS_RDF . ' Bag' ) {
 879                         array_unshift( $this->mode, self::MODE_LI );
 880                 } else {
 881                         throw new RuntimeException( "Expected <rdf:Bag> but got $elm." );
 882                 }
 883         }
 884
 885         /**
 886          * Start element in MODE_SEQ (ordered array)
 887          * this should always be <rdf:Seq>
 888          *
 889          * @param string $elm Namespace . ' ' . tag
 890          * @throws RuntimeException If we have an element that's not <rdf:Seq>
 891          */
 892         private function startElementModeSeq( $elm ) {
 893                 if ( $elm === self::NS_RDF . ' Seq' ) {
 894                         array_unshift( $this->mode, self::MODE_LI );
 895                 } elseif ( $elm === self::NS_RDF . ' Bag' ) {
 896                         # bug 27105
 897                         $this->logger->info( __METHOD__ . ' Expected an rdf:Seq, but got an rdf:Bag. Pretending'
 898                                 . ' it is a Seq, since some buggy software is known to screw this up.' );
 899                         array_unshift( $this->mode, self::MODE_LI );
 900                 } else {
 901                         throw new RuntimeException( "Expected <rdf:Seq> but got $elm." );
 902                 }
 903         }
 904
 905         /**
 906          * Start element in MODE_LANG (language alternative)
 907          * this should always be <rdf:Alt>
 908          *
 909          * This tag tends to be used for metadata like describe this
 910          * picture, which can be translated into multiple languages.
 911          *
 912          * XMP supports non-linguistic alternative selections,
 913          * which are really only used for thumbnails, which
 914          * we don't care about.
 915          *
 916          * @param string $elm Namespace . ' ' . tag
 917          * @throws RuntimeException If we have an element that's not <rdf:Alt>
 918          */
 919         private function startElementModeLang( $elm ) {
 920                 if ( $elm === self::NS_RDF . ' Alt' ) {
 921                         array_unshift( $this->mode, self::MODE_LI_LANG );
 922                 } else {
 923                         throw new RuntimeException( "Expected <rdf:Seq> but got $elm." );
 924                 }
 925         }
 926
 927         /**
 928          * Handle an opening element when in MODE_SIMPLE
 929          *
 930          * This should not happen often. This is for if a simple element
 931          * already opened has a child element. Could happen for a
 932          * qualified element.
 933          *
 934          * For example:
 935          * <exif:DigitalZoomRatio><rdf:Description><rdf:value>0/10</rdf:value>
 936          *   <foo:someQualifier>Bar</foo:someQualifier> </rdf:Description>
 937          *   </exif:DigitalZoomRatio>
 938          *
 939          * This method is called when processing the <rdf:Description> element
 940          *
 941          * @param string $elm Namespace and tag names separated by space.
 942          * @param array $attribs Attributes of the element.
 943          * @throws RuntimeException
 944          */
 945         private function startElementModeSimple( $elm, $attribs ) {
 946                 if ( $elm === self::NS_RDF . ' Description' ) {
 947                         // If this value has qualifiers
 948                         array_unshift( $this->mode, self::MODE_QDESC );
 949                         array_unshift( $this->curItem, $this->curItem[0] );
 950
 951                         if ( isset( $attribs[self::NS_RDF . ' value'] ) ) {
 952                                 list( $ns, $tag ) = explode( ' ', $this->curItem[0], 2 );
 953                                 $this->saveValue( $ns, $tag, $attribs[self::NS_RDF . ' value'] );
 954                         }
 955                 } elseif ( $elm === self::NS_RDF . ' value' ) {
 956                         // This should not be here.
 957                         throw new RuntimeException( __METHOD__ . ' Encountered <rdf:value> where it was unexpected.' );
 958                 } else {
 959                         // something else we don't recognize, like a qualifier maybe.
 960                         $this->logger->info( __METHOD__ .
 961                                 " Encountered element <$elm> where only expecting character data as value of " .
 962                                 $this->curItem[0] );
 963                         array_unshift( $this->mode, self::MODE_IGNORE );
 964                         array_unshift( $this->curItem, $elm );
 965                 }
 966         }
 967
 968         /**
 969          * Start an element when in MODE_QDESC.
 970          * This generally happens when a simple element has an inner
 971          * rdf:Description to hold qualifier elements.
 972          *
 973          * For example in:
 974          * <exif:DigitalZoomRatio><rdf:Description><rdf:value>0/10</rdf:value>
 975          *   <foo:someQualifier>Bar</foo:someQualifier> </rdf:Description>
 976          *   </exif:DigitalZoomRatio>
 977          * Called when processing the <rdf:value> or <foo:someQualifier>.
 978          *
 979          * @param string $elm Namespace and tag name separated by a space.
 980          *
 981          */
 982         private function startElementModeQDesc( $elm ) {
 983                 if ( $elm === self::NS_RDF . ' value' ) {
 984                         return; // do nothing
 985                 } else {
 986                         // otherwise its a qualifier, which we ignore
 987                         array_unshift( $this->mode, self::MODE_IGNORE );
 988                         array_unshift( $this->curItem, $elm );
 989                 }
 990         }
 991
 992         /**
 993          * Starting an element when in MODE_INITIAL
 994          * This usually happens when we hit an element inside
 995          * the outer rdf:Description
 996          *
 997          * This is generally where most properties start.
 998          *
 999          * @param string $ns Namespace
1000          * @param string $tag Tag name (without namespace prefix)
1001          * @param array $attribs Array of attributes
1002          * @throws RuntimeException
1003          */
1004         private function startElementModeInitial( $ns, $tag, $attribs ) {
1005                 if ( $ns !== self::NS_RDF ) {
1006
1007                         if ( isset( $this->items[$ns][$tag] ) ) {
1008                                 if ( isset( $this->items[$ns][$tag]['structPart'] ) ) {
1009                                         // If this element is supposed to appear only as
1010                                         // a child of a structure, but appears here (not as
1011                                         // a child of a struct), then something weird is
1012                                         // happening, so ignore this element and its children.
1013
1014                                         $this->logger->warning( "Encountered <$ns:$tag> outside"
1015                                                 . " of its expected parent. Ignoring." );
1016
1017                                         array_unshift( $this->mode, self::MODE_IGNORE );
1018                                         array_unshift( $this->curItem, $ns . ' ' . $tag );
1019
1020                                         return;
1021                                 }
1022                                 $mode = $this->items[$ns][$tag]['mode'];
1023                                 array_unshift( $this->mode, $mode );
1024                                 array_unshift( $this->curItem, $ns . ' ' . $tag );
1025                                 if ( $mode === self::MODE_STRUCT ) {
1026                                         $this->ancestorStruct = isset( $this->items[$ns][$tag]['map_name'] )
1027                                                 ? $this->items[$ns][$tag]['map_name'] : $tag;
1028                                 }
1029                                 if ( $this->charContent !== false ) {
1030                                         // Something weird.
1031                                         // Should not happen in valid XMP.
1032                                         throw new RuntimeException( 'tag nested in non-whitespace characters.' );
1033                                 }
1034                         } else {
1035                                 // This element is not on our list of allowed elements so ignore.
1036                                 $this->logger->debug( __METHOD__ . " Ignoring unrecognized element <$ns:$tag>." );
1037                                 array_unshift( $this->mode, self::MODE_IGNORE );
1038                                 array_unshift( $this->curItem, $ns . ' ' . $tag );
1039
1040                                 return;
1041                         }
1042                 }
1043                 // process attributes
1044                 $this->doAttribs( $attribs );
1045         }
1046
1047         /**
1048          * Hit an opening element when in a Struct (MODE_STRUCT)
1049          * This is generally for fields of a compound property.
1050          *
1051          * Example of a struct (abbreviated; flash has more properties):
1052          *
1053          * <exif:Flash> <rdf:Description> <exif:Fired>True</exif:Fired>
1054          *  <exif:Mode>1</exif:Mode></rdf:Description></exif:Flash>
1055          *
1056          * or:
1057          *
1058          * <exif:Flash rdf:parseType='Resource'> <exif:Fired>True</exif:Fired>
1059          *  <exif:Mode>1</exif:Mode></exif:Flash>
1060          *
1061          * @param string $ns Namespace
1062          * @param string $tag Tag name (no ns)
1063          * @param array $attribs Array of attribs w/ values.
1064          * @throws RuntimeException
1065          */
1066         private function startElementModeStruct( $ns, $tag, $attribs ) {
1067                 if ( $ns !== self::NS_RDF ) {
1068
1069                         if ( isset( $this->items[$ns][$tag] ) ) {
1070                                 if ( isset( $this->items[$ns][$this->ancestorStruct]['children'] )
1071                                         && !isset( $this->items[$ns][$this->ancestorStruct]['children'][$tag] )
1072                                 ) {
1073                                         // This assumes that we don't have inter-namespace nesting
1074                                         // which we don't in all the properties we're interested in.
1075                                         throw new RuntimeException( " <$tag> appeared nested in <" . $this->ancestorStruct
1076                                                 . "> where it is not allowed." );
1077                                 }
1078                                 array_unshift( $this->mode, $this->items[$ns][$tag]['mode'] );
1079                                 array_unshift( $this->curItem, $ns . ' ' . $tag );
1080                                 if ( $this->charContent !== false ) {
1081                                         // Something weird.
1082                                         // Should not happen in valid XMP.
1083                                         throw new RuntimeException( "tag <$tag> nested in non-whitespace characters (" .
1084                                                 $this->charContent . ")." );
1085                                 }
1086                         } else {
1087                                 array_unshift( $this->mode, self::MODE_IGNORE );
1088                                 array_unshift( $this->curItem, $elm );
1089
1090                                 return;
1091                         }
1092                 }
1093
1094                 if ( $ns === self::NS_RDF && $tag === 'Description' ) {
1095                         $this->doAttribs( $attribs );
1096                         array_unshift( $this->mode, self::MODE_STRUCT );
1097                         array_unshift( $this->curItem, $this->curItem[0] );
1098                 }
1099         }
1100
1101         /**
1102          * opening element in MODE_LI
1103          * process elements of arrays.
1104          *
1105          * Example:
1106          * <exif:ISOSpeedRatings> <rdf:Seq> <rdf:li>64</rdf:li>
1107          *   </rdf:Seq> </exif:ISOSpeedRatings>
1108          * This method is called when we hit the <rdf:li> element.
1109          *
1110          * @param string $elm Namespace . ' ' . tagname
1111          * @param array $attribs Attributes. (needed for BAGSTRUCTS)
1112          * @throws RuntimeException If gets a tag other than <rdf:li>
1113          */
1114         private function startElementModeLi( $elm, $attribs ) {
1115                 if ( ( $elm ) !== self::NS_RDF . ' li' ) {
1116                         throw new RuntimeException( "<rdf:li> expected but got $elm." );
1117                 }
1118
1119                 if ( !isset( $this->mode[1] ) ) {
1120                         // This should never ever ever happen. Checking for it
1121                         // to be paranoid.
1122                         throw new RuntimeException( 'In mode Li, but no 2xPrevious mode!' );
1123                 }
1124
1125                 if ( $this->mode[1] === self::MODE_BAGSTRUCT ) {
1126                         // This list item contains a compound (STRUCT) value.
1127                         array_unshift( $this->mode, self::MODE_STRUCT );
1128                         array_unshift( $this->curItem, $elm );
1129                         $this->processingArray = true;
1130
1131                         if ( !isset( $this->curItem[1] ) ) {
1132                                 // be paranoid.
1133                                 throw new RuntimeException( 'Can not find parent of BAGSTRUCT.' );
1134                         }
1135                         list( $curNS, $curTag ) = explode( ' ', $this->curItem[1] );
1136                         $this->ancestorStruct = isset( $this->items[$curNS][$curTag]['map_name'] )
1137                                 ? $this->items[$curNS][$curTag]['map_name'] : $curTag;
1138
1139                         $this->doAttribs( $attribs );
1140                 } else {
1141                         // Normal BAG or SEQ containing simple values.
1142                         array_unshift( $this->mode, self::MODE_SIMPLE );
1143                         // need to add curItem[0] on again since one is for the specific item
1144                         // and one is for the entire group.
1145                         array_unshift( $this->curItem, $this->curItem[0] );
1146                         $this->processingArray = true;
1147                 }
1148         }
1149
1150         /**
1151          * Opening element in MODE_LI_LANG.
1152          * process elements of language alternatives
1153          *
1154          * Example:
1155          * <dc:title> <rdf:Alt> <rdf:li xml:lang="x-default">My house
1156          *  </rdf:li> </rdf:Alt> </dc:title>
1157          *
1158          * This method is called when we hit the <rdf:li> element.
1159          *
1160          * @param string $elm Namespace . ' ' . tag
1161          * @param array $attribs Array of elements (most importantly xml:lang)
1162          * @throws RuntimeException If gets a tag other than <rdf:li> or if no xml:lang
1163          */
1164         private function startElementModeLiLang( $elm, $attribs ) {
1165                 if ( $elm !== self::NS_RDF . ' li' ) {
1166                         throw new RuntimeException( __METHOD__ . " <rdf:li> expected but got $elm." );
1167                 }
1168                 if ( !isset( $attribs[self::NS_XML . ' lang'] )
1169                         || !preg_match( '/^[-A-Za-z0-9]{2,}$/D', $attribs[self::NS_XML . ' lang'] )
1170                 ) {
1171                         throw new RuntimeException( __METHOD__
1172                                 . " <rdf:li> did not contain, or has invalid xml:lang attribute in lang alternative" );
1173                 }
1174
1175                 // Lang is case-insensitive.
1176                 $this->itemLang = strtolower( $attribs[self::NS_XML . ' lang'] );
1177
1178                 // need to add curItem[0] on again since one is for the specific item
1179                 // and one is for the entire group.
1180                 array_unshift( $this->curItem, $this->curItem[0] );
1181                 array_unshift( $this->mode, self::MODE_SIMPLE );
1182                 $this->processingArray = true;
1183         }
1184
1185         /**
1186          * Hits an opening element.
1187          * Generally just calls a helper based on what MODE we're in.
1188          * Also does some initial set up for the wrapper element
1189          *
1190          * @param XMLParser $parser
1191          * @param string $elm Namespace "<space>" element
1192          * @param array $attribs Attribute name => value
1193          * @throws RuntimeException
1194          */
1195         function startElement( $parser, $elm, $attribs ) {
1196
1197                 if ( $elm === self::NS_RDF . ' RDF'
1198                         || $elm === 'adobe:ns:meta/ xmpmeta'
1199                         || $elm === 'adobe:ns:meta/ xapmeta'
1200                 ) {
1201                         /* ignore. */
1202                         return;
1203                 } elseif ( $elm === self::NS_RDF . ' Description' ) {
1204                         if ( count( $this->mode ) === 0 ) {
1205                                 // outer rdf:desc
1206                                 array_unshift( $this->mode, self::MODE_INITIAL );
1207                         }
1208                 } elseif ( $elm === self::NS_RDF . ' type' ) {
1209                         // This doesn't support rdf:type properly.
1210                         // In practise I have yet to see a file that
1211                         // uses this element, however it is mentioned
1212                         // on page 25 of part 1 of the xmp standard.
1213                         //
1214                         // also it seems as if exiv2 and exiftool do not support
1215                         // this either (That or I misunderstand the standard)
1216                         $this->logger->info( __METHOD__ . ' Encountered <rdf:type> which isn\'t currently supported' );
1217                 }
1218
1219                 if ( strpos( $elm, ' ' ) === false ) {
1220                         // This probably shouldn't happen.
1221                         $this->logger->info( __METHOD__ . " Encountered <$elm> which has no namespace. Skipping." );
1222
1223                         return;
1224                 }
1225
1226                 list( $ns, $tag ) = explode( ' ', $elm, 2 );
1227
1228                 if ( count( $this->mode ) === 0 ) {
1229                         // This should not happen.
1230                         throw new RuntimeException( 'Error extracting XMP, '
1231                                 . "encountered <$elm> with no mode" );
1232                 }
1233
1234                 switch ( $this->mode[0] ) {
1235                         case self::MODE_IGNORE:
1236                                 $this->startElementModeIgnore( $elm );
1237                                 break;
1238                         case self::MODE_SIMPLE:
1239                                 $this->startElementModeSimple( $elm, $attribs );
1240                                 break;
1241                         case self::MODE_INITIAL:
1242                                 $this->startElementModeInitial( $ns, $tag, $attribs );
1243                                 break;
1244                         case self::MODE_STRUCT:
1245                                 $this->startElementModeStruct( $ns, $tag, $attribs );
1246                                 break;
1247                         case self::MODE_BAG:
1248                         case self::MODE_BAGSTRUCT:
1249                                 $this->startElementModeBag( $elm );
1250                                 break;
1251                         case self::MODE_SEQ:
1252                                 $this->startElementModeSeq( $elm );
1253                                 break;
1254                         case self::MODE_LANG:
1255                                 $this->startElementModeLang( $elm );
1256                                 break;
1257                         case self::MODE_LI_LANG:
1258                                 $this->startElementModeLiLang( $elm, $attribs );
1259                                 break;
1260                         case self::MODE_LI:
1261                                 $this->startElementModeLi( $elm, $attribs );
1262                                 break;
1263                         case self::MODE_QDESC:
1264                                 $this->startElementModeQDesc( $elm );
1265                                 break;
1266                         default:
1267                                 throw new RuntimeException( 'StartElement in unknown mode: ' . $this->mode[0] );
1268                 }
1269         }
1270
1271         /**
1272          * Process attributes.
1273          * Simple values can be stored as either a tag or attribute
1274          *
1275          * Often the initial "<rdf:Description>" tag just has all the simple
1276          * properties as attributes.
1277          *
1278          * @codingStandardsIgnoreStart Long line that cannot be broken
1279          * @par Example:
1280          * @code
1281          * <rdf:Description rdf:about="" xmlns:exif="http://ns.adobe.com/exif/1.0/" exif:DigitalZoomRatio="0/10">
1282          * @endcode
1283          * @codingStandardsIgnoreEnd
1284          *
1285          * @param array $attribs Array attribute=>value
1286          * @throws RuntimeException
1287          */
1288         private function doAttribs( $attribs ) {
1289                 // first check for rdf:parseType attribute, as that can change
1290                 // how the attributes are interperted.
1291
1292                 if ( isset( $attribs[self::NS_RDF . ' parseType'] )
1293                         && $attribs[self::NS_RDF . ' parseType'] === 'Resource'
1294                         && $this->mode[0] === self::MODE_SIMPLE
1295                 ) {
1296                         // this is equivalent to having an inner rdf:Description
1297                         $this->mode[0] = self::MODE_QDESC;
1298                 }
1299                 foreach ( $attribs as $name => $val ) {
1300                         if ( strpos( $name, ' ' ) === false ) {
1301                                 // This shouldn't happen, but so far some old software forgets namespace
1302                                 // on rdf:about.
1303                                 $this->logger->info( __METHOD__ . ' Encountered non-namespaced attribute: '
1304                                         . " $name=\"$val\". Skipping. " );
1305                                 continue;
1306                         }
1307                         list( $ns, $tag ) = explode( ' ', $name, 2 );
1308                         if ( $ns === self::NS_RDF ) {
1309                                 if ( $tag === 'value' || $tag === 'resource' ) {
1310                                         // resource is for url.
1311                                         // value attribute is a weird way of just putting the contents.
1312                                         $this->char( $this->xmlParser, $val );
1313                                 }
1314                         } elseif ( isset( $this->items[$ns][$tag] ) ) {
1315                                 if ( $this->mode[0] === self::MODE_SIMPLE ) {
1316                                         throw new RuntimeException( __METHOD__
1317                                                 . " $ns:$tag found as attribute where not allowed" );
1318                                 }
1319                                 $this->saveValue( $ns, $tag, $val );
1320                         } else {
1321                                 $this->logger->debug( __METHOD__ . " Ignoring unrecognized element <$ns:$tag>." );
1322                         }
1323                 }
1324         }
1325
1326         /**
1327          * Given an extracted value, save it to results array
1328          *
1329          * note also uses $this->ancestorStruct and
1330          * $this->processingArray to determine what name to
1331          * save the value under. (in addition to $tag).
1332          *
1333          * @param string $ns Namespace of tag this is for
1334          * @param string $tag Tag name
1335          * @param string $val Value to save
1336          */
1337         private function saveValue( $ns, $tag, $val ) {
1338
1339                 $info =& $this->items[$ns][$tag];
1340                 $finalName = isset( $info['map_name'] )
1341                         ? $info['map_name'] : $tag;
1342                 if ( isset( $info['validate'] ) ) {
1343                         if ( is_array( $info['validate'] ) ) {
1344                                 $validate = $info['validate'];
1345                         } else {
1346                                 $validator = new XMPValidate( $this->logger );
1347                                 $validate = array( $validator, $info['validate'] );
1348                         }
1349
1350                         if ( is_callable( $validate ) ) {
1351                                 call_user_func_array( $validate, array( $info, &$val, true ) );
1352                                 // the reasoning behind using &$val instead of using the return value
1353                                 // is to be consistent between here and validating structures.
1354                                 if ( is_null( $val ) ) {
1355                                         $this->logger->info( __METHOD__ . " <$ns:$tag> failed validation." );
1356
1357                                         return;
1358                                 }
1359                         } else {
1360                                 $this->logger->warning( __METHOD__ . " Validation function for $finalName ("
1361                                         . $validate[0] . '::' . $validate[1] . '()) is not callable.' );
1362                         }
1363                 }
1364
1365                 if ( $this->ancestorStruct && $this->processingArray ) {
1366                         // Aka both an array and a struct. ( self::MODE_BAGSTRUCT )
1367                         $this->results['xmp-' . $info['map_group']][$this->ancestorStruct][][$finalName] = $val;
1368                 } elseif ( $this->ancestorStruct ) {
1369                         $this->results['xmp-' . $info['map_group']][$this->ancestorStruct][$finalName] = $val;
1370                 } elseif ( $this->processingArray ) {
1371                         if ( $this->itemLang === false ) {
1372                                 // normal array
1373                                 $this->results['xmp-' . $info['map_group']][$finalName][] = $val;
1374                         } else {
1375                                 // lang array.
1376                                 $this->results['xmp-' . $info['map_group']][$finalName][$this->itemLang] = $val;
1377                         }
1378                 } else {
1379                         $this->results['xmp-' . $info['map_group']][$finalName] = $val;
1380                 }
1381         }
1382 }