includes/libs/xmp/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 use Wikimedia\ScopedCallback;
  28
  29 /**
  30  * Class for reading xmp data containing properties relevant to
  31  * images, and spitting out an array that FormatMetadata accepts.
  32  *
  33  * Note, this is not meant to recognize every possible thing you can
  34  * encode in XMP. It should recognize all the properties we want.
  35  * For example it doesn't have support for structures with multiple
  36  * nesting levels, as none of the properties we're supporting use that
  37  * feature. If it comes across properties it doesn't recognize, it should
  38  * ignore them.
  39  *
  40  * The public methods one would call in this class are
  41  * - parse( $content )
  42  *    Reads in xmp content.
  43  *    Can potentially be called multiple times with partial data each time.
  44  * - parseExtended( $content )
  45  *    Reads XMPExtended blocks (jpeg files only).
  46  * - getResults
  47  *    Outputs a results array.
  48  *
  49  * Note XMP kind of looks like rdf. They are not the same thing - XMP is
  50  * encoded as a specific subset of rdf. This class can read XMP. It cannot
  51  * read rdf.
  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 = [];
  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 = [];
  68
  69         /** @var array Array to hold results */
  70         private $results = [];
  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          * Primary job is to initialize the XMLParser
 134          */
 135         function __construct( LoggerInterface $logger = null ) {
 136                 if ( !function_exists( 'xml_parser_create_ns' ) ) {
 137                         // this should already be checked by this point
 138                         throw new RuntimeException( 'XMP support requires XML Parser' );
 139                 }
 140                 if ( $logger ) {
 141                         $this->setLogger( $logger );
 142                 } else {
 143                         $this->setLogger( new NullLogger() );
 144                 }
 145
 146                 $this->items = XMPInfo::getItems();
 147
 148                 $this->resetXMLParser();
 149         }
 150
 151         public function setLogger( LoggerInterface $logger ) {
 152                 $this->logger = $logger;
 153         }
 154
 155         /**
 156          * free the XML parser.
 157          *
 158          * @note It is unclear to me if we really need to do this ourselves
 159          *  or if php garbage collection will automatically free the xmlParser
 160          *  when it is no longer needed.
 161          */
 162         private function destroyXMLParser() {
 163                 if ( $this->xmlParser ) {
 164                         xml_parser_free( $this->xmlParser );
 165                         $this->xmlParser = null;
 166                 }
 167         }
 168
 169         /**
 170          * Main use is if a single item has multiple xmp documents describing it.
 171          * For example in jpeg's with extendedXMP
 172          */
 173         private function resetXMLParser() {
 174                 $this->destroyXMLParser();
 175
 176                 $this->xmlParser = xml_parser_create_ns( 'UTF-8', ' ' );
 177                 xml_parser_set_option( $this->xmlParser, XML_OPTION_CASE_FOLDING, 0 );
 178                 xml_parser_set_option( $this->xmlParser, XML_OPTION_SKIP_WHITE, 1 );
 179
 180                 xml_set_element_handler( $this->xmlParser,
 181                         [ $this, 'startElement' ],
 182                         [ $this, 'endElement' ] );
 183
 184                 xml_set_character_data_handler( $this->xmlParser, [ $this, 'char' ] );
 185
 186                 $this->parsable = self::PARSABLE_UNKNOWN;
 187                 $this->xmlParsableBuffer = '';
 188         }
 189
 190         /**
 191          * Check if this instance supports using this class
 192          */
 193         public static function isSupported() {
 194                 return function_exists( 'xml_parser_create_ns' ) && class_exists( 'XMLReader' );
 195         }
 196
 197         /** Get the result array. Do some post-processing before returning
 198          * the array, and transform any metadata that is special-cased.
 199          *
 200          * @return array Array of results as an array of arrays suitable for
 201          *    FormatMetadata::getFormattedData().
 202          */
 203         public function getResults() {
 204                 // xmp-special is for metadata that affects how stuff
 205                 // is extracted. For example xmpNote:HasExtendedXMP.
 206
 207                 // It is also used to handle photoshop:AuthorsPosition
 208                 // which is weird and really part of another property,
 209                 // see 2:85 in IPTC. See also pg 21 of IPTC4XMP standard.
 210                 // The location fields also use it.
 211
 212                 $data = $this->results;
 213
 214                 if ( isset( $data['xmp-special']['AuthorsPosition'] )
 215                         && is_string( $data['xmp-special']['AuthorsPosition'] )
 216                         && isset( $data['xmp-general']['Artist'][0] )
 217                 ) {
 218                         // Note, if there is more than one creator,
 219                         // this only applies to first. This also will
 220                         // only apply to the dc:Creator prop, not the
 221                         // exif:Artist prop.
 222
 223                         $data['xmp-general']['Artist'][0] =
 224                                 $data['xmp-special']['AuthorsPosition'] . ', '
 225                                 . $data['xmp-general']['Artist'][0];
 226                 }
 227
 228                 // Go through the LocationShown and LocationCreated
 229                 // changing it to the non-hierarchal form used by
 230                 // the other location fields.
 231
 232                 if ( isset( $data['xmp-special']['LocationShown'][0] )
 233                         && is_array( $data['xmp-special']['LocationShown'][0] )
 234                 ) {
 235                         // the is_array is just paranoia. It should always
 236                         // be an array.
 237                         foreach ( $data['xmp-special']['LocationShown'] as $loc ) {
 238                                 if ( !is_array( $loc ) ) {
 239                                         // To avoid copying over the _type meta-fields.
 240                                         continue;
 241                                 }
 242                                 foreach ( $loc as $field => $val ) {
 243                                         $data['xmp-general'][$field . 'Dest'][] = $val;
 244                                 }
 245                         }
 246                 }
 247                 if ( isset( $data['xmp-special']['LocationCreated'][0] )
 248                         && is_array( $data['xmp-special']['LocationCreated'][0] )
 249                 ) {
 250                         // the is_array is just paranoia. It should always
 251                         // be an array.
 252                         foreach ( $data['xmp-special']['LocationCreated'] as $loc ) {
 253                                 if ( !is_array( $loc ) ) {
 254                                         // To avoid copying over the _type meta-fields.
 255                                         continue;
 256                                 }
 257                                 foreach ( $loc as $field => $val ) {
 258                                         $data['xmp-general'][$field . 'Created'][] = $val;
 259                                 }
 260                         }
 261                 }
 262
 263                 // We don't want to return the special values, since they're
 264                 // special and not info to be stored about the file.
 265                 unset( $data['xmp-special'] );
 266
 267                 // Convert GPSAltitude to negative if below sea level.
 268                 if ( isset( $data['xmp-exif']['GPSAltitudeRef'] )
 269                         && isset( $data['xmp-exif']['GPSAltitude'] )
 270                 ) {
 271                         // Must convert to a real before multiplying by -1
 272                         // XMPValidate guarantees there will always be a '/' in this value.
 273                         list( $nom, $denom ) = explode( '/', $data['xmp-exif']['GPSAltitude'] );
 274                         $data['xmp-exif']['GPSAltitude'] = $nom / $denom;
 275
 276                         if ( $data['xmp-exif']['GPSAltitudeRef'] == '1' ) {
 277                                 $data['xmp-exif']['GPSAltitude'] *= -1;
 278                         }
 279                         unset( $data['xmp-exif']['GPSAltitudeRef'] );
 280                 }
 281
 282                 return $data;
 283         }
 284
 285         /**
 286          * Main function to call to parse XMP. Use getResults to
 287          * get results.
 288          *
 289          * Also catches any errors during processing, writes them to
 290          * debug log, blanks result array and returns false.
 291          *
 292          * @param string $content XMP data
 293          * @param bool $allOfIt If this is all the data (true) or if its split up (false). Default true
 294          * @throws RuntimeException
 295          * @return bool Success.
 296          */
 297         public function parse( $content, $allOfIt = true ) {
 298                 if ( !$this->xmlParser ) {
 299                         $this->resetXMLParser();
 300                 }
 301                 try {
 302
 303                         // detect encoding by looking for BOM which is supposed to be in processing instruction.
 304                         // see page 12 of http://www.adobe.com/devnet/xmp/pdfs/XMPSpecificationPart3.pdf
 305                         if ( !$this->charset ) {
 306                                 $bom = [];
 307                                 if ( preg_match( '/\xEF\xBB\xBF|\xFE\xFF|\x00\x00\xFE\xFF|\xFF\xFE\x00\x00|\xFF\xFE/',
 308                                         $content, $bom )
 309                                 ) {
 310                                         switch ( $bom[0] ) {
 311                                                 case "\xFE\xFF":
 312                                                         $this->charset = 'UTF-16BE';
 313                                                         break;
 314                                                 case "\xFF\xFE":
 315                                                         $this->charset = 'UTF-16LE';
 316                                                         break;
 317                                                 case "\x00\x00\xFE\xFF":
 318                                                         $this->charset = 'UTF-32BE';
 319                                                         break;
 320                                                 case "\xFF\xFE\x00\x00":
 321                                                         $this->charset = 'UTF-32LE';
 322                                                         break;
 323                                                 case "\xEF\xBB\xBF":
 324                                                         $this->charset = 'UTF-8';
 325                                                         break;
 326                                                 default:
 327                                                         // this should be impossible to get to
 328                                                         throw new RuntimeException( "Invalid BOM" );
 329                                         }
 330                                 } else {
 331                                         // standard specifically says, if no bom assume utf-8
 332                                         $this->charset = 'UTF-8';
 333                                 }
 334                         }
 335                         if ( $this->charset !== 'UTF-8' ) {
 336                                 // don't convert if already utf-8
 337                                 MediaWiki\suppressWarnings();
 338                                 $content = iconv( $this->charset, 'UTF-8//IGNORE', $content );
 339                                 MediaWiki\restoreWarnings();
 340                         }
 341
 342                         // Ensure the XMP block does not have an xml doctype declaration, which
 343                         // could declare entities unsafe to parse with xml_parse (T85848/T71210).
 344                         if ( $this->parsable !== self::PARSABLE_OK ) {
 345                                 if ( $this->parsable === self::PARSABLE_NO ) {
 346                                         throw new RuntimeException( 'Unsafe doctype declaration in XML.' );
 347                                 }
 348
 349                                 $content = $this->xmlParsableBuffer . $content;
 350                                 if ( !$this->checkParseSafety( $content ) ) {
 351                                         if ( !$allOfIt && $this->parsable !== self::PARSABLE_NO ) {
 352                                                 // parse wasn't Unsuccessful yet, so return true
 353                                                 // in this case.
 354                                                 return true;
 355                                         }
 356                                         $msg = ( $this->parsable === self::PARSABLE_NO ) ?
 357                                                 'Unsafe doctype declaration in XML.' :
 358                                                 'No root element found in XML.';
 359                                         throw new RuntimeException( $msg );
 360                                 }
 361                         }
 362
 363                         $ok = xml_parse( $this->xmlParser, $content, $allOfIt );
 364                         if ( !$ok ) {
 365                                 $code = xml_get_error_code( $this->xmlParser );
 366                                 $error = xml_error_string( $code );
 367                                 $line = xml_get_current_line_number( $this->xmlParser );
 368                                 $col = xml_get_current_column_number( $this->xmlParser );
 369                                 $offset = xml_get_current_byte_index( $this->xmlParser );
 370
 371                                 $this->logger->warning(
 372                                         '{method} : Error reading XMP content: {error} ' .
 373                                         '(line: {line} column: {column} byte offset: {offset})',
 374                                         [
 375                                                 'method' => __METHOD__,
 376                                                 'error_code' => $code,
 377                                                 'error' => $error,
 378                                                 'line' => $line,
 379                                                 'column' => $col,
 380                                                 'offset' => $offset,
 381                                                 'content' => $content,
 382                                 ] );
 383                                 $this->results = []; // blank if error.
 384                                 $this->destroyXMLParser();
 385                                 return false;
 386                         }
 387                 } catch ( Exception $e ) {
 388                         $this->logger->warning(
 389                                 '{method} Exception caught while parsing: ' . $e->getMessage(),
 390                                 [
 391                                         'method' => __METHOD__,
 392                                         'exception' => $e,
 393                                         'content' => $content,
 394                                 ]
 395                         );
 396                         $this->results = [];
 397                         return false;
 398                 }
 399                 if ( $allOfIt ) {
 400                         $this->destroyXMLParser();
 401                 }
 402
 403                 return true;
 404         }
 405
 406         /** Entry point for XMPExtended blocks in jpeg files
 407          *
 408          * @todo In serious need of testing
 409          * @see http://www.adobe.ge/devnet/xmp/pdfs/XMPSpecificationPart3.pdf XMP spec part 3 page 20
 410          * @param string $content XMPExtended block minus the namespace signature
 411          * @return bool If it succeeded.
 412          */
 413         public function parseExtended( $content ) {
 414                 // @todo FIXME: This is untested. Hard to find example files
 415                 // or programs that make such files..
 416                 $guid = substr( $content, 0, 32 );
 417                 if ( !isset( $this->results['xmp-special']['HasExtendedXMP'] )
 418                         || $this->results['xmp-special']['HasExtendedXMP'] !== $guid
 419                 ) {
 420                         $this->logger->info( __METHOD__ .
 421                                 " Ignoring XMPExtended block due to wrong guid (guid= '$guid')" );
 422
 423                         return false;
 424                 }
 425                 $len = unpack( 'Nlength/Noffset', substr( $content, 32, 8 ) );
 426
 427                 if ( !$len ||
 428                         $len['length'] < 4 ||
 429                         $len['offset'] < 0 ||
 430                         $len['offset'] > $len['length']
 431                 ) {
 432                         $this->logger->info(
 433                                 __METHOD__ . 'Error reading extended XMP block, invalid length or offset.'
 434                         );
 435
 436                         return false;
 437                 }
 438
 439                 // we're not very robust here. we should accept it in the wrong order.
 440                 // To quote the XMP standard:
 441                 // "A JPEG writer should write the ExtendedXMP marker segments in order,
 442                 // immediately following the StandardXMP. However, the JPEG standard
 443                 // does not require preservation of marker segment order. A robust JPEG
 444                 // reader should tolerate the marker segments in any order."
 445                 // On the other hand, the probability that an image will have more than
 446                 // 128k of metadata is rather low... so the probability that it will have
 447                 // > 128k, and be in the wrong order is very low...
 448
 449                 if ( $len['offset'] !== $this->extendedXMPOffset ) {
 450                         $this->logger->info( __METHOD__ . 'Ignoring XMPExtended block due to wrong order. (Offset was '
 451                                 . $len['offset'] . ' but expected ' . $this->extendedXMPOffset . ')' );
 452
 453                         return false;
 454                 }
 455
 456                 if ( $len['offset'] === 0 ) {
 457                         // if we're starting the extended block, we've probably already
 458                         // done the XMPStandard block, so reset.
 459                         $this->resetXMLParser();
 460                 }
 461
 462                 $this->extendedXMPOffset += $len['length'];
 463
 464                 $actualContent = substr( $content, 40 );
 465
 466                 if ( $this->extendedXMPOffset === strlen( $actualContent ) ) {
 467                         $atEnd = true;
 468                 } else {
 469                         $atEnd = false;
 470                 }
 471
 472                 $this->logger->debug( __METHOD__ . 'Parsing a XMPExtended block' );
 473
 474                 return $this->parse( $actualContent, $atEnd );
 475         }
 476
 477         /**
 478          * Character data handler
 479          * Called whenever character data is found in the xmp document.
 480          *
 481          * does nothing if we're in MODE_IGNORE or if the data is whitespace
 482          * throws an error if we're not in MODE_SIMPLE (as we're not allowed to have character
 483          * data in the other modes).
 484          *
 485          * As an example, this happens when we encounter XMP like:
 486          * <exif:DigitalZoomRatio>0/10</exif:DigitalZoomRatio>
 487          * and are processing the 0/10 bit.
 488          *
 489          * @param resource $parser XMLParser reference to the xml parser
 490          * @param string $data Character data
 491          * @throws RuntimeException On invalid data
 492          */
 493         function char( $parser, $data ) {
 494                 $data = trim( $data );
 495                 if ( trim( $data ) === "" ) {
 496                         return;
 497                 }
 498
 499                 if ( !isset( $this->mode[0] ) ) {
 500                         throw new RuntimeException( 'Unexpected character data before first rdf:Description element' );
 501                 }
 502
 503                 if ( $this->mode[0] === self::MODE_IGNORE ) {
 504                         return;
 505                 }
 506
 507                 if ( $this->mode[0] !== self::MODE_SIMPLE
 508                         && $this->mode[0] !== self::MODE_QDESC
 509                 ) {
 510                         throw new RuntimeException( 'character data where not expected. (mode ' . $this->mode[0] . ')' );
 511                 }
 512
 513                 // to check, how does this handle w.s.
 514                 if ( $this->charContent === false ) {
 515                         $this->charContent = $data;
 516                 } else {
 517                         $this->charContent .= $data;
 518                 }
 519         }
 520
 521         /**
 522          * Check if a block of XML is safe to pass to xml_parse, i.e. doesn't
 523          * contain a doctype declaration which could contain a dos attack if we
 524          * parse it and expand internal entities (T85848).
 525          *
 526          * @param string $content xml string to check for parse safety
 527          * @return bool true if the xml is safe to parse, false otherwise
 528          */
 529         private function checkParseSafety( $content ) {
 530                 $reader = new XMLReader();
 531                 $result = null;
 532
 533                 // For XMLReader to parse incomplete/invalid XML, it has to be open()'ed
 534                 // instead of using XML().
 535                 $reader->open(
 536                         'data://text/plain,' . urlencode( $content ),
 537                         null,
 538                         LIBXML_NOERROR | LIBXML_NOWARNING | LIBXML_NONET
 539                 );
 540
 541                 $oldDisable = libxml_disable_entity_loader( true );
 542                 /** @noinspection PhpUnusedLocalVariableInspection */
 543                 $reset = new ScopedCallback(
 544                         'libxml_disable_entity_loader',
 545                         [ $oldDisable ]
 546                 );
 547                 $reader->setParserProperty( XMLReader::SUBST_ENTITIES, false );
 548
 549                 // Even with LIBXML_NOWARNING set, XMLReader::read gives a warning
 550                 // when parsing truncated XML, which causes unit tests to fail.
 551                 MediaWiki\suppressWarnings();
 552                 while ( $reader->read() ) {
 553                         if ( $reader->nodeType === XMLReader::ELEMENT ) {
 554                                 // Reached the first element without hitting a doctype declaration
 555                                 $this->parsable = self::PARSABLE_OK;
 556                                 $result = true;
 557                                 break;
 558                         }
 559                         if ( $reader->nodeType === XMLReader::DOC_TYPE ) {
 560                                 $this->parsable = self::PARSABLE_NO;
 561                                 $result = false;
 562                                 break;
 563                         }
 564                 }
 565                 MediaWiki\restoreWarnings();
 566
 567                 if ( !is_null( $result ) ) {
 568                         return $result;
 569                 }
 570
 571                 // Reached the end of the parsable xml without finding an element
 572                 // or doctype. Buffer and try again.
 573                 $this->parsable = self::PARSABLE_BUFFERING;
 574                 $this->xmlParsableBuffer = $content;
 575                 return false;
 576         }
 577
 578         /** When we hit a closing element in MODE_IGNORE
 579          * Check to see if this is the element we started to ignore,
 580          * in which case we get out of MODE_IGNORE
 581          *
 582          * @param string $elm Namespace of element followed by a space and then tag name of element.
 583          */
 584         private function endElementModeIgnore( $elm ) {
 585                 if ( $this->curItem[0] === $elm ) {
 586                         array_shift( $this->curItem );
 587                         array_shift( $this->mode );
 588                 }
 589         }
 590
 591         /**
 592          * Hit a closing element when in MODE_SIMPLE.
 593          * This generally means that we finished processing a
 594          * property value, and now have to save the result to the
 595          * results array
 596          *
 597          * For example, when processing:
 598          * <exif:DigitalZoomRatio>0/10</exif:DigitalZoomRatio>
 599          * this deals with when we hit </exif:DigitalZoomRatio>.
 600          *
 601          * Or it could be if we hit the end element of a property
 602          * of a compound data structure (like a member of an array).
 603          *
 604          * @param string $elm Namespace, space, and tag name.
 605          */
 606         private function endElementModeSimple( $elm ) {
 607                 if ( $this->charContent !== false ) {
 608                         if ( $this->processingArray ) {
 609                                 // if we're processing an array, use the original element
 610                                 // name instead of rdf:li.
 611                                 list( $ns, $tag ) = explode( ' ', $this->curItem[0], 2 );
 612                         } else {
 613                                 list( $ns, $tag ) = explode( ' ', $elm, 2 );
 614                         }
 615                         $this->saveValue( $ns, $tag, $this->charContent );
 616
 617                         $this->charContent = false; // reset
 618                 }
 619                 array_shift( $this->curItem );
 620                 array_shift( $this->mode );
 621         }
 622
 623         /**
 624          * Hit a closing element in MODE_STRUCT, MODE_SEQ, MODE_BAG
 625          * generally means we've finished processing a nested structure.
 626          * resets some internal variables to indicate that.
 627          *
 628          * Note this means we hit the closing element not the "</rdf:Seq>".
 629          *
 630          * @par For example, when processing:
 631          * @code{,xml}
 632          * <exif:ISOSpeedRatings> <rdf:Seq> <rdf:li>64</rdf:li>
 633          *   </rdf:Seq> </exif:ISOSpeedRatings>
 634          * @endcode
 635          *
 636          * This method is called when we hit the "</exif:ISOSpeedRatings>" tag.
 637          *
 638          * @param string $elm Namespace . space . tag name.
 639          * @throws RuntimeException
 640          */
 641         private function endElementNested( $elm ) {
 642                 /* cur item must be the same as $elm, unless if in MODE_STRUCT
 643                  * in which case it could also be rdf:Description */
 644                 if ( $this->curItem[0] !== $elm
 645                         && !( $elm === self::NS_RDF . ' Description'
 646                                 && $this->mode[0] === self::MODE_STRUCT )
 647                 ) {
 648                         throw new RuntimeException( "nesting mismatch. got a </$elm> but expected a </" .
 649                                 $this->curItem[0] . '>' );
 650                 }
 651
 652                 // Validate structures.
 653                 list( $ns, $tag ) = explode( ' ', $elm, 2 );
 654                 if ( isset( $this->items[$ns][$tag]['validate'] ) ) {
 655                         $info =& $this->items[$ns][$tag];
 656                         $finalName = isset( $info['map_name'] )
 657                                 ? $info['map_name'] : $tag;
 658
 659                         if ( is_array( $info['validate'] ) ) {
 660                                 $validate = $info['validate'];
 661                         } else {
 662                                 $validator = new XMPValidate( $this->logger );
 663                                 $validate = [ $validator, $info['validate'] ];
 664                         }
 665
 666                         if ( !isset( $this->results['xmp-' . $info['map_group']][$finalName] ) ) {
 667                                 // This can happen if all the members of the struct failed validation.
 668                                 $this->logger->debug( __METHOD__ . " <$ns:$tag> has no valid members." );
 669                         } elseif ( is_callable( $validate ) ) {
 670                                 $val =& $this->results['xmp-' . $info['map_group']][$finalName];
 671                                 call_user_func_array( $validate, [ $info, &$val, false ] );
 672                                 if ( is_null( $val ) ) {
 673                                         // the idea being the validation function will unset the variable if
 674                                         // its invalid.
 675                                         $this->logger->info( __METHOD__ . " <$ns:$tag> failed validation." );
 676                                         unset( $this->results['xmp-' . $info['map_group']][$finalName] );
 677                                 }
 678                         } else {
 679                                 $this->logger->warning( __METHOD__ . " Validation function for $finalName ("
 680                                         . $validate[0] . '::' . $validate[1] . '()) is not callable.' );
 681                         }
 682                 }
 683
 684                 array_shift( $this->curItem );
 685                 array_shift( $this->mode );
 686                 $this->ancestorStruct = false;
 687                 $this->processingArray = false;
 688                 $this->itemLang = false;
 689         }
 690
 691         /**
 692          * Hit a closing element in MODE_LI (either rdf:Seq, or rdf:Bag )
 693          * Add information about what type of element this is.
 694          *
 695          * Note we still have to hit the outer "</property>"
 696          *
 697          * @par For example, when processing:
 698          * @code{,xml}
 699          * <exif:ISOSpeedRatings> <rdf:Seq> <rdf:li>64</rdf:li>
 700          *   </rdf:Seq> </exif:ISOSpeedRatings>
 701          * @endcode
 702          *
 703          * This method is called when we hit the "</rdf:Seq>".
 704          * (For comparison, we call endElementModeSimple when we
 705          * hit the "</rdf:li>")
 706          *
 707          * @param string $elm Namespace . ' ' . element name
 708          * @throws RuntimeException
 709          */
 710         private function endElementModeLi( $elm ) {
 711                 list( $ns, $tag ) = explode( ' ', $this->curItem[0], 2 );
 712                 $info = $this->items[$ns][$tag];
 713                 $finalName = isset( $info['map_name'] )
 714                         ? $info['map_name'] : $tag;
 715
 716                 array_shift( $this->mode );
 717
 718                 if ( !isset( $this->results['xmp-' . $info['map_group']][$finalName] ) ) {
 719                         $this->logger->debug( __METHOD__ . " Empty compund element $finalName." );
 720
 721                         return;
 722                 }
 723
 724                 if ( $elm === self::NS_RDF . ' Seq' ) {
 725                         $this->results['xmp-' . $info['map_group']][$finalName]['_type'] = 'ol';
 726                 } elseif ( $elm === self::NS_RDF . ' Bag' ) {
 727                         $this->results['xmp-' . $info['map_group']][$finalName]['_type'] = 'ul';
 728                 } elseif ( $elm === self::NS_RDF . ' Alt' ) {
 729                         // extra if needed as you could theoretically have a non-language alt.
 730                         if ( $info['mode'] === self::MODE_LANG ) {
 731                                 $this->results['xmp-' . $info['map_group']][$finalName]['_type'] = 'lang';
 732                         }
 733                 } else {
 734                         throw new RuntimeException(
 735                                 __METHOD__ . " expected </rdf:seq> or </rdf:bag> but instead got $elm."
 736                         );
 737                 }
 738         }
 739
 740         /**
 741          * End element while in MODE_QDESC
 742          * mostly when ending an element when we have a simple value
 743          * that has qualifiers.
 744          *
 745          * Qualifiers aren't all that common, and we don't do anything
 746          * with them.
 747          *
 748          * @param string $elm Namespace and element
 749          */
 750         private function endElementModeQDesc( $elm ) {
 751                 if ( $elm === self::NS_RDF . ' value' ) {
 752                         list( $ns, $tag ) = explode( ' ', $this->curItem[0], 2 );
 753                         $this->saveValue( $ns, $tag, $this->charContent );
 754
 755                         return;
 756                 } else {
 757                         array_shift( $this->mode );
 758                         array_shift( $this->curItem );
 759                 }
 760         }
 761
 762         /**
 763          * Handler for hitting a closing element.
 764          *
 765          * generally just calls a helper function depending on what
 766          * mode we're in.
 767          *
 768          * Ignores the outer wrapping elements that are optional in
 769          * xmp and have no meaning.
 770          *
 771          * @param resource $parser
 772          * @param string $elm Namespace . ' ' . element name
 773          * @throws RuntimeException
 774          */
 775         function endElement( $parser, $elm ) {
 776                 if ( $elm === ( self::NS_RDF . ' RDF' )
 777                         || $elm === 'adobe:ns:meta/ xmpmeta'
 778                         || $elm === 'adobe:ns:meta/ xapmeta'
 779                 ) {
 780                         // ignore these.
 781                         return;
 782                 }
 783
 784                 if ( $elm === self::NS_RDF . ' type' ) {
 785                         // these aren't really supported properly yet.
 786                         // However, it appears they almost never used.
 787                         $this->logger->info( __METHOD__ . ' encountered <rdf:type>' );
 788                 }
 789
 790                 if ( strpos( $elm, ' ' ) === false ) {
 791                         // This probably shouldn't happen.
 792                         // However, there is a bug in an adobe product
 793                         // that forgets the namespace on some things.
 794                         // (Luckily they are unimportant things).
 795                         $this->logger->info( __METHOD__ . " Encountered </$elm> which has no namespace. Skipping." );
 796
 797                         return;
 798                 }
 799
 800                 if ( count( $this->mode[0] ) === 0 ) {
 801                         // This should never ever happen and means
 802                         // there is a pretty major bug in this class.
 803                         throw new RuntimeException( 'Encountered end element with no mode' );
 804                 }
 805
 806                 if ( count( $this->curItem ) == 0 && $this->mode[0] !== self::MODE_INITIAL ) {
 807                         // just to be paranoid. Should always have a curItem, except for initially
 808                         // (aka during MODE_INITAL).
 809                         throw new RuntimeException( "Hit end element </$elm> but no curItem" );
 810                 }
 811
 812                 switch ( $this->mode[0] ) {
 813                         case self::MODE_IGNORE:
 814                                 $this->endElementModeIgnore( $elm );
 815                                 break;
 816                         case self::MODE_SIMPLE:
 817                                 $this->endElementModeSimple( $elm );
 818                                 break;
 819                         case self::MODE_STRUCT:
 820                         case self::MODE_SEQ:
 821                         case self::MODE_BAG:
 822                         case self::MODE_LANG:
 823                         case self::MODE_BAGSTRUCT:
 824                                 $this->endElementNested( $elm );
 825                                 break;
 826                         case self::MODE_INITIAL:
 827                                 if ( $elm === self::NS_RDF . ' Description' ) {
 828                                         array_shift( $this->mode );
 829                                 } else {
 830                                         throw new RuntimeException( 'Element ended unexpectedly while in MODE_INITIAL' );
 831                                 }
 832                                 break;
 833                         case self::MODE_LI:
 834                         case self::MODE_LI_LANG:
 835                                 $this->endElementModeLi( $elm );
 836                                 break;
 837                         case self::MODE_QDESC:
 838                                 $this->endElementModeQDesc( $elm );
 839                                 break;
 840                         default:
 841                                 $this->logger->warning( __METHOD__ . " no mode (elm = $elm)" );
 842                                 break;
 843                 }
 844         }
 845
 846         /**
 847          * Hit an opening element while in MODE_IGNORE
 848          *
 849          * XMP is extensible, so ignore any tag we don't understand.
 850          *
 851          * Mostly ignores, unless we encounter the element that we are ignoring.
 852          * in which case we add it to the item stack, so we can ignore things
 853          * that are nested, correctly.
 854          *
 855          * @param string $elm Namespace . ' ' . tag name
 856          */
 857         private function startElementModeIgnore( $elm ) {
 858                 if ( $elm === $this->curItem[0] ) {
 859                         array_unshift( $this->curItem, $elm );
 860                         array_unshift( $this->mode, self::MODE_IGNORE );
 861                 }
 862         }
 863
 864         /**
 865          *  Start element in MODE_BAG (unordered array)
 866          * this should always be <rdf:Bag>
 867          *
 868          * @param string $elm Namespace . ' ' . tag
 869          * @throws RuntimeException If we have an element that's not <rdf:Bag>
 870          */
 871         private function startElementModeBag( $elm ) {
 872                 if ( $elm === self::NS_RDF . ' Bag' ) {
 873                         array_unshift( $this->mode, self::MODE_LI );
 874                 } else {
 875                         throw new RuntimeException( "Expected <rdf:Bag> but got $elm." );
 876                 }
 877         }
 878
 879         /**
 880          * Start element in MODE_SEQ (ordered array)
 881          * this should always be <rdf:Seq>
 882          *
 883          * @param string $elm Namespace . ' ' . tag
 884          * @throws RuntimeException If we have an element that's not <rdf:Seq>
 885          */
 886         private function startElementModeSeq( $elm ) {
 887                 if ( $elm === self::NS_RDF . ' Seq' ) {
 888                         array_unshift( $this->mode, self::MODE_LI );
 889                 } elseif ( $elm === self::NS_RDF . ' Bag' ) {
 890                         # T29105
 891                         $this->logger->info( __METHOD__ . ' Expected an rdf:Seq, but got an rdf:Bag. Pretending'
 892                                 . ' it is a Seq, since some buggy software is known to screw this up.' );
 893                         array_unshift( $this->mode, self::MODE_LI );
 894                 } else {
 895                         throw new RuntimeException( "Expected <rdf:Seq> but got $elm." );
 896                 }
 897         }
 898
 899         /**
 900          * Start element in MODE_LANG (language alternative)
 901          * this should always be <rdf:Alt>
 902          *
 903          * This tag tends to be used for metadata like describe this
 904          * picture, which can be translated into multiple languages.
 905          *
 906          * XMP supports non-linguistic alternative selections,
 907          * which are really only used for thumbnails, which
 908          * we don't care about.
 909          *
 910          * @param string $elm Namespace . ' ' . tag
 911          * @throws RuntimeException If we have an element that's not <rdf:Alt>
 912          */
 913         private function startElementModeLang( $elm ) {
 914                 if ( $elm === self::NS_RDF . ' Alt' ) {
 915                         array_unshift( $this->mode, self::MODE_LI_LANG );
 916                 } else {
 917                         throw new RuntimeException( "Expected <rdf:Seq> but got $elm." );
 918                 }
 919         }
 920
 921         /**
 922          * Handle an opening element when in MODE_SIMPLE
 923          *
 924          * This should not happen often. This is for if a simple element
 925          * already opened has a child element. Could happen for a
 926          * qualified element.
 927          *
 928          * For example:
 929          * <exif:DigitalZoomRatio><rdf:Description><rdf:value>0/10</rdf:value>
 930          *   <foo:someQualifier>Bar</foo:someQualifier> </rdf:Description>
 931          *   </exif:DigitalZoomRatio>
 932          *
 933          * This method is called when processing the <rdf:Description> element
 934          *
 935          * @param string $elm Namespace and tag names separated by space.
 936          * @param array $attribs Attributes of the element.
 937          * @throws RuntimeException
 938          */
 939         private function startElementModeSimple( $elm, $attribs ) {
 940                 if ( $elm === self::NS_RDF . ' Description' ) {
 941                         // If this value has qualifiers
 942                         array_unshift( $this->mode, self::MODE_QDESC );
 943                         array_unshift( $this->curItem, $this->curItem[0] );
 944
 945                         if ( isset( $attribs[self::NS_RDF . ' value'] ) ) {
 946                                 list( $ns, $tag ) = explode( ' ', $this->curItem[0], 2 );
 947                                 $this->saveValue( $ns, $tag, $attribs[self::NS_RDF . ' value'] );
 948                         }
 949                 } elseif ( $elm === self::NS_RDF . ' value' ) {
 950                         // This should not be here.
 951                         throw new RuntimeException( __METHOD__ . ' Encountered <rdf:value> where it was unexpected.' );
 952                 } else {
 953                         // something else we don't recognize, like a qualifier maybe.
 954                         $this->logger->info( __METHOD__ .
 955                                 " Encountered element <$elm> where only expecting character data as value of " .
 956                                 $this->curItem[0] );
 957                         array_unshift( $this->mode, self::MODE_IGNORE );
 958                         array_unshift( $this->curItem, $elm );
 959                 }
 960         }
 961
 962         /**
 963          * Start an element when in MODE_QDESC.
 964          * This generally happens when a simple element has an inner
 965          * rdf:Description to hold qualifier elements.
 966          *
 967          * For example in:
 968          * <exif:DigitalZoomRatio><rdf:Description><rdf:value>0/10</rdf:value>
 969          *   <foo:someQualifier>Bar</foo:someQualifier> </rdf:Description>
 970          *   </exif:DigitalZoomRatio>
 971          * Called when processing the <rdf:value> or <foo:someQualifier>.
 972          *
 973          * @param string $elm Namespace and tag name separated by a space.
 974          */
 975         private function startElementModeQDesc( $elm ) {
 976                 if ( $elm === self::NS_RDF . ' value' ) {
 977                         return; // do nothing
 978                 } else {
 979                         // otherwise its a qualifier, which we ignore
 980                         array_unshift( $this->mode, self::MODE_IGNORE );
 981                         array_unshift( $this->curItem, $elm );
 982                 }
 983         }
 984
 985         /**
 986          * Starting an element when in MODE_INITIAL
 987          * This usually happens when we hit an element inside
 988          * the outer rdf:Description
 989          *
 990          * This is generally where most properties start.
 991          *
 992          * @param string $ns Namespace
 993          * @param string $tag Tag name (without namespace prefix)
 994          * @param array $attribs Array of attributes
 995          * @throws RuntimeException
 996          */
 997         private function startElementModeInitial( $ns, $tag, $attribs ) {
 998                 if ( $ns !== self::NS_RDF ) {
 999                         if ( isset( $this->items[$ns][$tag] ) ) {
1000                                 if ( isset( $this->items[$ns][$tag]['structPart'] ) ) {
1001                                         // If this element is supposed to appear only as
1002                                         // a child of a structure, but appears here (not as
1003                                         // a child of a struct), then something weird is
1004                                         // happening, so ignore this element and its children.
1005
1006                                         $this->logger->warning( "Encountered <$ns:$tag> outside"
1007                                                 . " of its expected parent. Ignoring." );
1008
1009                                         array_unshift( $this->mode, self::MODE_IGNORE );
1010                                         array_unshift( $this->curItem, $ns . ' ' . $tag );
1011
1012                                         return;
1013                                 }
1014                                 $mode = $this->items[$ns][$tag]['mode'];
1015                                 array_unshift( $this->mode, $mode );
1016                                 array_unshift( $this->curItem, $ns . ' ' . $tag );
1017                                 if ( $mode === self::MODE_STRUCT ) {
1018                                         $this->ancestorStruct = isset( $this->items[$ns][$tag]['map_name'] )
1019                                                 ? $this->items[$ns][$tag]['map_name'] : $tag;
1020                                 }
1021                                 if ( $this->charContent !== false ) {
1022                                         // Something weird.
1023                                         // Should not happen in valid XMP.
1024                                         throw new RuntimeException( 'tag nested in non-whitespace characters.' );
1025                                 }
1026                         } else {
1027                                 // This element is not on our list of allowed elements so ignore.
1028                                 $this->logger->debug( __METHOD__ . " Ignoring unrecognized element <$ns:$tag>." );
1029                                 array_unshift( $this->mode, self::MODE_IGNORE );
1030                                 array_unshift( $this->curItem, $ns . ' ' . $tag );
1031
1032                                 return;
1033                         }
1034                 }
1035                 // process attributes
1036                 $this->doAttribs( $attribs );
1037         }
1038
1039         /**
1040          * Hit an opening element when in a Struct (MODE_STRUCT)
1041          * This is generally for fields of a compound property.
1042          *
1043          * Example of a struct (abbreviated; flash has more properties):
1044          *
1045          * <exif:Flash> <rdf:Description> <exif:Fired>True</exif:Fired>
1046          *  <exif:Mode>1</exif:Mode></rdf:Description></exif:Flash>
1047          *
1048          * or:
1049          *
1050          * <exif:Flash rdf:parseType='Resource'> <exif:Fired>True</exif:Fired>
1051          *  <exif:Mode>1</exif:Mode></exif:Flash>
1052          *
1053          * @param string $ns Namespace
1054          * @param string $tag Tag name (no ns)
1055          * @param array $attribs Array of attribs w/ values.
1056          * @throws RuntimeException
1057          */
1058         private function startElementModeStruct( $ns, $tag, $attribs ) {
1059                 if ( $ns !== self::NS_RDF ) {
1060                         if ( isset( $this->items[$ns][$tag] ) ) {
1061                                 if ( isset( $this->items[$ns][$this->ancestorStruct]['children'] )
1062                                         && !isset( $this->items[$ns][$this->ancestorStruct]['children'][$tag] )
1063                                 ) {
1064                                         // This assumes that we don't have inter-namespace nesting
1065                                         // which we don't in all the properties we're interested in.
1066                                         throw new RuntimeException( " <$tag> appeared nested in <" . $this->ancestorStruct
1067                                                 . "> where it is not allowed." );
1068                                 }
1069                                 array_unshift( $this->mode, $this->items[$ns][$tag]['mode'] );
1070                                 array_unshift( $this->curItem, $ns . ' ' . $tag );
1071                                 if ( $this->charContent !== false ) {
1072                                         // Something weird.
1073                                         // Should not happen in valid XMP.
1074                                         throw new RuntimeException( "tag <$tag> nested in non-whitespace characters (" .
1075                                                 $this->charContent . ")." );
1076                                 }
1077                         } else {
1078                                 array_unshift( $this->mode, self::MODE_IGNORE );
1079                                 array_unshift( $this->curItem, $ns . ' ' . $tag );
1080
1081                                 return;
1082                         }
1083                 }
1084
1085                 if ( $ns === self::NS_RDF && $tag === 'Description' ) {
1086                         $this->doAttribs( $attribs );
1087                         array_unshift( $this->mode, self::MODE_STRUCT );
1088                         array_unshift( $this->curItem, $this->curItem[0] );
1089                 }
1090         }
1091
1092         /**
1093          * opening element in MODE_LI
1094          * process elements of arrays.
1095          *
1096          * Example:
1097          * <exif:ISOSpeedRatings> <rdf:Seq> <rdf:li>64</rdf:li>
1098          *   </rdf:Seq> </exif:ISOSpeedRatings>
1099          * This method is called when we hit the <rdf:li> element.
1100          *
1101          * @param string $elm Namespace . ' ' . tagname
1102          * @param array $attribs Attributes. (needed for BAGSTRUCTS)
1103          * @throws RuntimeException If gets a tag other than <rdf:li>
1104          */
1105         private function startElementModeLi( $elm, $attribs ) {
1106                 if ( ( $elm ) !== self::NS_RDF . ' li' ) {
1107                         throw new RuntimeException( "<rdf:li> expected but got $elm." );
1108                 }
1109
1110                 if ( !isset( $this->mode[1] ) ) {
1111                         // This should never ever ever happen. Checking for it
1112                         // to be paranoid.
1113                         throw new RuntimeException( 'In mode Li, but no 2xPrevious mode!' );
1114                 }
1115
1116                 if ( $this->mode[1] === self::MODE_BAGSTRUCT ) {
1117                         // This list item contains a compound (STRUCT) value.
1118                         array_unshift( $this->mode, self::MODE_STRUCT );
1119                         array_unshift( $this->curItem, $elm );
1120                         $this->processingArray = true;
1121
1122                         if ( !isset( $this->curItem[1] ) ) {
1123                                 // be paranoid.
1124                                 throw new RuntimeException( 'Can not find parent of BAGSTRUCT.' );
1125                         }
1126                         list( $curNS, $curTag ) = explode( ' ', $this->curItem[1] );
1127                         $this->ancestorStruct = isset( $this->items[$curNS][$curTag]['map_name'] )
1128                                 ? $this->items[$curNS][$curTag]['map_name'] : $curTag;
1129
1130                         $this->doAttribs( $attribs );
1131                 } else {
1132                         // Normal BAG or SEQ containing simple values.
1133                         array_unshift( $this->mode, self::MODE_SIMPLE );
1134                         // need to add curItem[0] on again since one is for the specific item
1135                         // and one is for the entire group.
1136                         array_unshift( $this->curItem, $this->curItem[0] );
1137                         $this->processingArray = true;
1138                 }
1139         }
1140
1141         /**
1142          * Opening element in MODE_LI_LANG.
1143          * process elements of language alternatives
1144          *
1145          * Example:
1146          * <dc:title> <rdf:Alt> <rdf:li xml:lang="x-default">My house
1147          *  </rdf:li> </rdf:Alt> </dc:title>
1148          *
1149          * This method is called when we hit the <rdf:li> element.
1150          *
1151          * @param string $elm Namespace . ' ' . tag
1152          * @param array $attribs Array of elements (most importantly xml:lang)
1153          * @throws RuntimeException If gets a tag other than <rdf:li> or if no xml:lang
1154          */
1155         private function startElementModeLiLang( $elm, $attribs ) {
1156                 if ( $elm !== self::NS_RDF . ' li' ) {
1157                         throw new RuntimeException( __METHOD__ . " <rdf:li> expected but got $elm." );
1158                 }
1159                 if ( !isset( $attribs[self::NS_XML . ' lang'] )
1160                         || !preg_match( '/^[-A-Za-z0-9]{2,}$/D', $attribs[self::NS_XML . ' lang'] )
1161                 ) {
1162                         throw new RuntimeException( __METHOD__
1163                                 . " <rdf:li> did not contain, or has invalid xml:lang attribute in lang alternative" );
1164                 }
1165
1166                 // Lang is case-insensitive.
1167                 $this->itemLang = strtolower( $attribs[self::NS_XML . ' lang'] );
1168
1169                 // need to add curItem[0] on again since one is for the specific item
1170                 // and one is for the entire group.
1171                 array_unshift( $this->curItem, $this->curItem[0] );
1172                 array_unshift( $this->mode, self::MODE_SIMPLE );
1173                 $this->processingArray = true;
1174         }
1175
1176         /**
1177          * Hits an opening element.
1178          * Generally just calls a helper based on what MODE we're in.
1179          * Also does some initial set up for the wrapper element
1180          *
1181          * @param resource $parser
1182          * @param string $elm Namespace "<space>" element
1183          * @param array $attribs Attribute name => value
1184          * @throws RuntimeException
1185          */
1186         function startElement( $parser, $elm, $attribs ) {
1187                 if ( $elm === self::NS_RDF . ' RDF'
1188                         || $elm === 'adobe:ns:meta/ xmpmeta'
1189                         || $elm === 'adobe:ns:meta/ xapmeta'
1190                 ) {
1191                         /* ignore. */
1192                         return;
1193                 } elseif ( $elm === self::NS_RDF . ' Description' ) {
1194                         if ( count( $this->mode ) === 0 ) {
1195                                 // outer rdf:desc
1196                                 array_unshift( $this->mode, self::MODE_INITIAL );
1197                         }
1198                 } elseif ( $elm === self::NS_RDF . ' type' ) {
1199                         // This doesn't support rdf:type properly.
1200                         // In practise I have yet to see a file that
1201                         // uses this element, however it is mentioned
1202                         // on page 25 of part 1 of the xmp standard.
1203                         // Also it seems as if exiv2 and exiftool do not support
1204                         // this either (That or I misunderstand the standard)
1205                         $this->logger->info( __METHOD__ . ' Encountered <rdf:type> which isn\'t currently supported' );
1206                 }
1207
1208                 if ( strpos( $elm, ' ' ) === false ) {
1209                         // This probably shouldn't happen.
1210                         $this->logger->info( __METHOD__ . " Encountered <$elm> which has no namespace. Skipping." );
1211
1212                         return;
1213                 }
1214
1215                 list( $ns, $tag ) = explode( ' ', $elm, 2 );
1216
1217                 if ( count( $this->mode ) === 0 ) {
1218                         // This should not happen.
1219                         throw new RuntimeException( 'Error extracting XMP, '
1220                                 . "encountered <$elm> with no mode" );
1221                 }
1222
1223                 switch ( $this->mode[0] ) {
1224                         case self::MODE_IGNORE:
1225                                 $this->startElementModeIgnore( $elm );
1226                                 break;
1227                         case self::MODE_SIMPLE:
1228                                 $this->startElementModeSimple( $elm, $attribs );
1229                                 break;
1230                         case self::MODE_INITIAL:
1231                                 $this->startElementModeInitial( $ns, $tag, $attribs );
1232                                 break;
1233                         case self::MODE_STRUCT:
1234                                 $this->startElementModeStruct( $ns, $tag, $attribs );
1235                                 break;
1236                         case self::MODE_BAG:
1237                         case self::MODE_BAGSTRUCT:
1238                                 $this->startElementModeBag( $elm );
1239                                 break;
1240                         case self::MODE_SEQ:
1241                                 $this->startElementModeSeq( $elm );
1242                                 break;
1243                         case self::MODE_LANG:
1244                                 $this->startElementModeLang( $elm );
1245                                 break;
1246                         case self::MODE_LI_LANG:
1247                                 $this->startElementModeLiLang( $elm, $attribs );
1248                                 break;
1249                         case self::MODE_LI:
1250                                 $this->startElementModeLi( $elm, $attribs );
1251                                 break;
1252                         case self::MODE_QDESC:
1253                                 $this->startElementModeQDesc( $elm );
1254                                 break;
1255                         default:
1256                                 throw new RuntimeException( 'StartElement in unknown mode: ' . $this->mode[0] );
1257                 }
1258         }
1259
1260         // @codingStandardsIgnoreStart Generic.Files.LineLength
1261         /**
1262          * Process attributes.
1263          * Simple values can be stored as either a tag or attribute
1264          *
1265          * Often the initial "<rdf:Description>" tag just has all the simple
1266          * properties as attributes.
1267          *
1268          * @par Example:
1269          * @code
1270          * <rdf:Description rdf:about="" xmlns:exif="http://ns.adobe.com/exif/1.0/" exif:DigitalZoomRatio="0/10">
1271          * @endcode
1272          *
1273          * @param array $attribs Array attribute=>value
1274          * @throws RuntimeException
1275          */
1276         // @codingStandardsIgnoreEnd
1277         private function doAttribs( $attribs ) {
1278                 // first check for rdf:parseType attribute, as that can change
1279                 // how the attributes are interperted.
1280
1281                 if ( isset( $attribs[self::NS_RDF . ' parseType'] )
1282                         && $attribs[self::NS_RDF . ' parseType'] === 'Resource'
1283                         && $this->mode[0] === self::MODE_SIMPLE
1284                 ) {
1285                         // this is equivalent to having an inner rdf:Description
1286                         $this->mode[0] = self::MODE_QDESC;
1287                 }
1288                 foreach ( $attribs as $name => $val ) {
1289                         if ( strpos( $name, ' ' ) === false ) {
1290                                 // This shouldn't happen, but so far some old software forgets namespace
1291                                 // on rdf:about.
1292                                 $this->logger->info( __METHOD__ . ' Encountered non-namespaced attribute: '
1293                                         . " $name=\"$val\". Skipping. " );
1294                                 continue;
1295                         }
1296                         list( $ns, $tag ) = explode( ' ', $name, 2 );
1297                         if ( $ns === self::NS_RDF ) {
1298                                 if ( $tag === 'value' || $tag === 'resource' ) {
1299                                         // resource is for url.
1300                                         // value attribute is a weird way of just putting the contents.
1301                                         $this->char( $this->xmlParser, $val );
1302                                 }
1303                         } elseif ( isset( $this->items[$ns][$tag] ) ) {
1304                                 if ( $this->mode[0] === self::MODE_SIMPLE ) {
1305                                         throw new RuntimeException( __METHOD__
1306                                                 . " $ns:$tag found as attribute where not allowed" );
1307                                 }
1308                                 $this->saveValue( $ns, $tag, $val );
1309                         } else {
1310                                 $this->logger->debug( __METHOD__ . " Ignoring unrecognized element <$ns:$tag>." );
1311                         }
1312                 }
1313         }
1314
1315         /**
1316          * Given an extracted value, save it to results array
1317          *
1318          * note also uses $this->ancestorStruct and
1319          * $this->processingArray to determine what name to
1320          * save the value under. (in addition to $tag).
1321          *
1322          * @param string $ns Namespace of tag this is for
1323          * @param string $tag Tag name
1324          * @param string $val Value to save
1325          */
1326         private function saveValue( $ns, $tag, $val ) {
1327                 $info =& $this->items[$ns][$tag];
1328                 $finalName = isset( $info['map_name'] )
1329                         ? $info['map_name'] : $tag;
1330                 if ( isset( $info['validate'] ) ) {
1331                         if ( is_array( $info['validate'] ) ) {
1332                                 $validate = $info['validate'];
1333                         } else {
1334                                 $validator = new XMPValidate( $this->logger );
1335                                 $validate = [ $validator, $info['validate'] ];
1336                         }
1337
1338                         if ( is_callable( $validate ) ) {
1339                                 call_user_func_array( $validate, [ $info, &$val, true ] );
1340                                 // the reasoning behind using &$val instead of using the return value
1341                                 // is to be consistent between here and validating structures.
1342                                 if ( is_null( $val ) ) {
1343                                         $this->logger->info( __METHOD__ . " <$ns:$tag> failed validation." );
1344
1345                                         return;
1346                                 }
1347                         } else {
1348                                 $this->logger->warning( __METHOD__ . " Validation function for $finalName ("
1349                                         . $validate[0] . '::' . $validate[1] . '()) is not callable.' );
1350                         }
1351                 }
1352
1353                 if ( $this->ancestorStruct && $this->processingArray ) {
1354                         // Aka both an array and a struct. ( self::MODE_BAGSTRUCT )
1355                         $this->results['xmp-' . $info['map_group']][$this->ancestorStruct][][$finalName] = $val;
1356                 } elseif ( $this->ancestorStruct ) {
1357                         $this->results['xmp-' . $info['map_group']][$this->ancestorStruct][$finalName] = $val;
1358                 } elseif ( $this->processingArray ) {
1359                         if ( $this->itemLang === false ) {
1360                                 // normal array
1361                                 $this->results['xmp-' . $info['map_group']][$finalName][] = $val;
1362                         } else {
1363                                 // lang array.
1364                                 $this->results['xmp-' . $info['map_group']][$finalName][$this->itemLang] = $val;
1365                         }
1366                 } else {
1367                         $this->results['xmp-' . $info['map_group']][$finalName] = $val;
1368                 }
1369         }
1370 }