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          * @param LoggerInterface|null $logger
 135          */
 136         function __construct( LoggerInterface $logger = null ) {
 137                 if ( !function_exists( 'xml_parser_create_ns' ) ) {
 138                         // this should already be checked by this point
 139                         throw new RuntimeException( 'XMP support requires XML Parser' );
 140                 }
 141                 if ( $logger ) {
 142                         $this->setLogger( $logger );
 143                 } else {
 144                         $this->setLogger( new NullLogger() );
 145                 }
 146
 147                 $this->items = XMPInfo::getItems();
 148
 149                 $this->resetXMLParser();
 150         }
 151
 152         public function setLogger( LoggerInterface $logger ) {
 153                 $this->logger = $logger;
 154         }
 155
 156         /**
 157          * free the XML parser.
 158          *
 159          * @note It is unclear to me if we really need to do this ourselves
 160          *  or if php garbage collection will automatically free the xmlParser
 161          *  when it is no longer needed.
 162          */
 163         private function destroyXMLParser() {
 164                 if ( $this->xmlParser ) {
 165                         xml_parser_free( $this->xmlParser );
 166                         $this->xmlParser = null;
 167                 }
 168         }
 169
 170         /**
 171          * Main use is if a single item has multiple xmp documents describing it.
 172          * For example in jpeg's with extendedXMP
 173          */
 174         private function resetXMLParser() {
 175                 $this->destroyXMLParser();
 176
 177                 $this->xmlParser = xml_parser_create_ns( 'UTF-8', ' ' );
 178                 xml_parser_set_option( $this->xmlParser, XML_OPTION_CASE_FOLDING, 0 );
 179                 xml_parser_set_option( $this->xmlParser, XML_OPTION_SKIP_WHITE, 1 );
 180
 181                 xml_set_element_handler( $this->xmlParser,
 182                         [ $this, 'startElement' ],
 183                         [ $this, 'endElement' ] );
 184
 185                 xml_set_character_data_handler( $this->xmlParser, [ $this, 'char' ] );
 186
 187                 $this->parsable = self::PARSABLE_UNKNOWN;
 188                 $this->xmlParsableBuffer = '';
 189         }
 190
 191         /**
 192          * Check if this instance supports using this class
 193          * @return bool
 194          */
 195         public static function isSupported() {
 196                 return function_exists( 'xml_parser_create_ns' ) && class_exists( 'XMLReader' );
 197         }
 198
 199         /** Get the result array. Do some post-processing before returning
 200          * the array, and transform any metadata that is special-cased.
 201          *
 202          * @return array Array of results as an array of arrays suitable for
 203          *    FormatMetadata::getFormattedData().
 204          */
 205         public function getResults() {
 206                 // xmp-special is for metadata that affects how stuff
 207                 // is extracted. For example xmpNote:HasExtendedXMP.
 208
 209                 // It is also used to handle photoshop:AuthorsPosition
 210                 // which is weird and really part of another property,
 211                 // see 2:85 in IPTC. See also pg 21 of IPTC4XMP standard.
 212                 // The location fields also use it.
 213
 214                 $data = $this->results;
 215
 216                 if ( isset( $data['xmp-special']['AuthorsPosition'] )
 217                         && is_string( $data['xmp-special']['AuthorsPosition'] )
 218                         && isset( $data['xmp-general']['Artist'][0] )
 219                 ) {
 220                         // Note, if there is more than one creator,
 221                         // this only applies to first. This also will
 222                         // only apply to the dc:Creator prop, not the
 223                         // exif:Artist prop.
 224
 225                         $data['xmp-general']['Artist'][0] =
 226                                 $data['xmp-special']['AuthorsPosition'] . ', '
 227                                 . $data['xmp-general']['Artist'][0];
 228                 }
 229
 230                 // Go through the LocationShown and LocationCreated
 231                 // changing it to the non-hierarchal form used by
 232                 // the other location fields.
 233
 234                 if ( isset( $data['xmp-special']['LocationShown'][0] )
 235                         && is_array( $data['xmp-special']['LocationShown'][0] )
 236                 ) {
 237                         // the is_array is just paranoia. It should always
 238                         // be an array.
 239                         foreach ( $data['xmp-special']['LocationShown'] as $loc ) {
 240                                 if ( !is_array( $loc ) ) {
 241                                         // To avoid copying over the _type meta-fields.
 242                                         continue;
 243                                 }
 244                                 foreach ( $loc as $field => $val ) {
 245                                         $data['xmp-general'][$field . 'Dest'][] = $val;
 246                                 }
 247                         }
 248                 }
 249                 if ( isset( $data['xmp-special']['LocationCreated'][0] )
 250                         && is_array( $data['xmp-special']['LocationCreated'][0] )
 251                 ) {
 252                         // the is_array is just paranoia. It should always
 253                         // be an array.
 254                         foreach ( $data['xmp-special']['LocationCreated'] as $loc ) {
 255                                 if ( !is_array( $loc ) ) {
 256                                         // To avoid copying over the _type meta-fields.
 257                                         continue;
 258                                 }
 259                                 foreach ( $loc as $field => $val ) {
 260                                         $data['xmp-general'][$field . 'Created'][] = $val;
 261                                 }
 262                         }
 263                 }
 264
 265                 // We don't want to return the special values, since they're
 266                 // special and not info to be stored about the file.
 267                 unset( $data['xmp-special'] );
 268
 269                 // Convert GPSAltitude to negative if below sea level.
 270                 if ( isset( $data['xmp-exif']['GPSAltitudeRef'] )
 271                         && isset( $data['xmp-exif']['GPSAltitude'] )
 272                 ) {
 273                         // Must convert to a real before multiplying by -1
 274                         // XMPValidate guarantees there will always be a '/' in this value.
 275                         list( $nom, $denom ) = explode( '/', $data['xmp-exif']['GPSAltitude'] );
 276                         $data['xmp-exif']['GPSAltitude'] = $nom / $denom;
 277
 278                         if ( $data['xmp-exif']['GPSAltitudeRef'] == '1' ) {
 279                                 $data['xmp-exif']['GPSAltitude'] *= -1;
 280                         }
 281                         unset( $data['xmp-exif']['GPSAltitudeRef'] );
 282                 }
 283
 284                 return $data;
 285         }
 286
 287         /**
 288          * Main function to call to parse XMP. Use getResults to
 289          * get results.
 290          *
 291          * Also catches any errors during processing, writes them to
 292          * debug log, blanks result array and returns false.
 293          *
 294          * @param string $content XMP data
 295          * @param bool $allOfIt If this is all the data (true) or if its split up (false). Default true
 296          * @throws RuntimeException
 297          * @return bool Success.
 298          */
 299         public function parse( $content, $allOfIt = true ) {
 300                 if ( !$this->xmlParser ) {
 301                         $this->resetXMLParser();
 302                 }
 303                 try {
 304
 305                         // detect encoding by looking for BOM which is supposed to be in processing instruction.
 306                         // see page 12 of http://www.adobe.com/devnet/xmp/pdfs/XMPSpecificationPart3.pdf
 307                         if ( !$this->charset ) {
 308                                 $bom = [];
 309                                 if ( preg_match( '/\xEF\xBB\xBF|\xFE\xFF|\x00\x00\xFE\xFF|\xFF\xFE\x00\x00|\xFF\xFE/',
 310                                         $content, $bom )
 311                                 ) {
 312                                         switch ( $bom[0] ) {
 313                                                 case "\xFE\xFF":
 314                                                         $this->charset = 'UTF-16BE';
 315                                                         break;
 316                                                 case "\xFF\xFE":
 317                                                         $this->charset = 'UTF-16LE';
 318                                                         break;
 319                                                 case "\x00\x00\xFE\xFF":
 320                                                         $this->charset = 'UTF-32BE';
 321                                                         break;
 322                                                 case "\xFF\xFE\x00\x00":
 323                                                         $this->charset = 'UTF-32LE';
 324                                                         break;
 325                                                 case "\xEF\xBB\xBF":
 326                                                         $this->charset = 'UTF-8';
 327                                                         break;
 328                                                 default:
 329                                                         // this should be impossible to get to
 330                                                         throw new RuntimeException( "Invalid BOM" );
 331                                         }
 332                                 } else {
 333                                         // standard specifically says, if no bom assume utf-8
 334                                         $this->charset = 'UTF-8';
 335                                 }
 336                         }
 337                         if ( $this->charset !== 'UTF-8' ) {
 338                                 // don't convert if already utf-8
 339                                 MediaWiki\suppressWarnings();
 340                                 $content = iconv( $this->charset, 'UTF-8//IGNORE', $content );
 341                                 MediaWiki\restoreWarnings();
 342                         }
 343
 344                         // Ensure the XMP block does not have an xml doctype declaration, which
 345                         // could declare entities unsafe to parse with xml_parse (T85848/T71210).
 346                         if ( $this->parsable !== self::PARSABLE_OK ) {
 347                                 if ( $this->parsable === self::PARSABLE_NO ) {
 348                                         throw new RuntimeException( 'Unsafe doctype declaration in XML.' );
 349                                 }
 350
 351                                 $content = $this->xmlParsableBuffer . $content;
 352                                 if ( !$this->checkParseSafety( $content ) ) {
 353                                         if ( !$allOfIt && $this->parsable !== self::PARSABLE_NO ) {
 354                                                 // parse wasn't Unsuccessful yet, so return true
 355                                                 // in this case.
 356                                                 return true;
 357                                         }
 358                                         $msg = ( $this->parsable === self::PARSABLE_NO ) ?
 359                                                 'Unsafe doctype declaration in XML.' :
 360                                                 'No root element found in XML.';
 361                                         throw new RuntimeException( $msg );
 362                                 }
 363                         }
 364
 365                         $ok = xml_parse( $this->xmlParser, $content, $allOfIt );
 366                         if ( !$ok ) {
 367                                 $code = xml_get_error_code( $this->xmlParser );
 368                                 $error = xml_error_string( $code );
 369                                 $line = xml_get_current_line_number( $this->xmlParser );
 370                                 $col = xml_get_current_column_number( $this->xmlParser );
 371                                 $offset = xml_get_current_byte_index( $this->xmlParser );
 372
 373                                 $this->logger->info(
 374                                         '{method} : Error reading XMP content: {error} ' .
 375                                         '(line: {line} column: {column} byte offset: {offset})',
 376                                         [
 377                                                 'method' => __METHOD__,
 378                                                 'error_code' => $code,
 379                                                 'error' => $error,
 380                                                 'line' => $line,
 381                                                 'column' => $col,
 382                                                 'offset' => $offset,
 383                                                 'content' => $content,
 384                                 ] );
 385                                 $this->results = []; // blank if error.
 386                                 $this->destroyXMLParser();
 387                                 return false;
 388                         }
 389                 } catch ( Exception $e ) {
 390                         $this->logger->warning(
 391                                 '{method} {exception}',
 392                                 [
 393                                         'method' => __METHOD__,
 394                                         'exception' => $e,
 395                                         'content' => $content,
 396                                 ]
 397                         );
 398                         $this->results = [];
 399                         return false;
 400                 }
 401                 if ( $allOfIt ) {
 402                         $this->destroyXMLParser();
 403                 }
 404
 405                 return true;
 406         }
 407
 408         /** Entry point for XMPExtended blocks in jpeg files
 409          *
 410          * @todo In serious need of testing
 411          * @see http://www.adobe.ge/devnet/xmp/pdfs/XMPSpecificationPart3.pdf XMP spec part 3 page 20
 412          * @param string $content XMPExtended block minus the namespace signature
 413          * @return bool If it succeeded.
 414          */
 415         public function parseExtended( $content ) {
 416                 // @todo FIXME: This is untested. Hard to find example files
 417                 // or programs that make such files..
 418                 $guid = substr( $content, 0, 32 );
 419                 if ( !isset( $this->results['xmp-special']['HasExtendedXMP'] )
 420                         || $this->results['xmp-special']['HasExtendedXMP'] !== $guid
 421                 ) {
 422                         $this->logger->info( __METHOD__ .
 423                                 " Ignoring XMPExtended block due to wrong guid (guid= '{guid}')",
 424                                 [ 'guid' => 'guid' ] );
 425
 426                         return false;
 427                 }
 428                 $len = unpack( 'Nlength/Noffset', substr( $content, 32, 8 ) );
 429
 430                 if ( !$len ||
 431                         $len['length'] < 4 ||
 432                         $len['offset'] < 0 ||
 433                         $len['offset'] > $len['length']
 434                 ) {
 435                         $this->logger->info(
 436                                 __METHOD__ . 'Error reading extended XMP block, invalid length or offset.'
 437                         );
 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                 // On the other hand, the probability that an image will have more than
 449                 // 128k of metadata is rather low... so the probability that it will have
 450                 // > 128k, and be in the wrong order is very low...
 451
 452                 if ( $len['offset'] !== $this->extendedXMPOffset ) {
 453                         $this->logger->info( __METHOD__ . 'Ignoring XMPExtended block due to wrong order. (Offset was '
 454                                 . $len['offset'] . ' but expected ' . $this->extendedXMPOffset . ')' );
 455
 456                         return false;
 457                 }
 458
 459                 if ( $len['offset'] === 0 ) {
 460                         // if we're starting the extended block, we've probably already
 461                         // done the XMPStandard block, so reset.
 462                         $this->resetXMLParser();
 463                 }
 464
 465                 $this->extendedXMPOffset += $len['length'];
 466
 467                 $actualContent = substr( $content, 40 );
 468
 469                 if ( $this->extendedXMPOffset === strlen( $actualContent ) ) {
 470                         $atEnd = true;
 471                 } else {
 472                         $atEnd = false;
 473                 }
 474
 475                 $this->logger->debug( __METHOD__ . 'Parsing a XMPExtended block' );
 476
 477                 return $this->parse( $actualContent, $atEnd );
 478         }
 479
 480         /**
 481          * Character data handler
 482          * Called whenever character data is found in the xmp document.
 483          *
 484          * does nothing if we're in MODE_IGNORE or if the data is whitespace
 485          * throws an error if we're not in MODE_SIMPLE (as we're not allowed to have character
 486          * data in the other modes).
 487          *
 488          * As an example, this happens when we encounter XMP like:
 489          * <exif:DigitalZoomRatio>0/10</exif:DigitalZoomRatio>
 490          * and are processing the 0/10 bit.
 491          *
 492          * @param resource $parser XMLParser reference to the xml parser
 493          * @param string $data Character data
 494          * @throws RuntimeException On invalid data
 495          */
 496         function char( $parser, $data ) {
 497                 $data = trim( $data );
 498                 if ( trim( $data ) === "" ) {
 499                         return;
 500                 }
 501
 502                 if ( !isset( $this->mode[0] ) ) {
 503                         throw new RuntimeException( 'Unexpected character data before first rdf:Description element' );
 504                 }
 505
 506                 if ( $this->mode[0] === self::MODE_IGNORE ) {
 507                         return;
 508                 }
 509
 510                 if ( $this->mode[0] !== self::MODE_SIMPLE
 511                         && $this->mode[0] !== self::MODE_QDESC
 512                 ) {
 513                         throw new RuntimeException( 'character data where not expected. (mode ' . $this->mode[0] . ')' );
 514                 }
 515
 516                 // to check, how does this handle w.s.
 517                 if ( $this->charContent === false ) {
 518                         $this->charContent = $data;
 519                 } else {
 520                         $this->charContent .= $data;
 521                 }
 522         }
 523
 524         /**
 525          * Check if a block of XML is safe to pass to xml_parse, i.e. doesn't
 526          * contain a doctype declaration which could contain a dos attack if we
 527          * parse it and expand internal entities (T85848).
 528          *
 529          * @param string $content xml string to check for parse safety
 530          * @return bool true if the xml is safe to parse, false otherwise
 531          */
 532         private function checkParseSafety( $content ) {
 533                 $reader = new XMLReader();
 534                 $result = null;
 535
 536                 // For XMLReader to parse incomplete/invalid XML, it has to be open()'ed
 537                 // instead of using XML().
 538                 $reader->open(
 539                         'data://text/plain,' . urlencode( $content ),
 540                         null,
 541                         LIBXML_NOERROR | LIBXML_NOWARNING | LIBXML_NONET
 542                 );
 543
 544                 $oldDisable = libxml_disable_entity_loader( true );
 545                 /** @noinspection PhpUnusedLocalVariableInspection */
 546                 $reset = new ScopedCallback(
 547                         'libxml_disable_entity_loader',
 548                         [ $oldDisable ]
 549                 );
 550                 $reader->setParserProperty( XMLReader::SUBST_ENTITIES, false );
 551
 552                 // Even with LIBXML_NOWARNING set, XMLReader::read gives a warning
 553                 // when parsing truncated XML, which causes unit tests to fail.
 554                 MediaWiki\suppressWarnings();
 555                 while ( $reader->read() ) {
 556                         if ( $reader->nodeType === XMLReader::ELEMENT ) {
 557                                 // Reached the first element without hitting a doctype declaration
 558                                 $this->parsable = self::PARSABLE_OK;
 559                                 $result = true;
 560                                 break;
 561                         }
 562                         if ( $reader->nodeType === XMLReader::DOC_TYPE ) {
 563                                 $this->parsable = self::PARSABLE_NO;
 564                                 $result = false;
 565                                 break;
 566                         }
 567                 }
 568                 MediaWiki\restoreWarnings();
 569
 570                 if ( !is_null( $result ) ) {
 571                         return $result;
 572                 }
 573
 574                 // Reached the end of the parsable xml without finding an element
 575                 // or doctype. Buffer and try again.
 576                 $this->parsable = self::PARSABLE_BUFFERING;
 577                 $this->xmlParsableBuffer = $content;
 578                 return false;
 579         }
 580
 581         /** When we hit a closing element in MODE_IGNORE
 582          * Check to see if this is the element we started to ignore,
 583          * in which case we get out of MODE_IGNORE
 584          *
 585          * @param string $elm Namespace of element followed by a space and then tag name of element.
 586          */
 587         private function endElementModeIgnore( $elm ) {
 588                 if ( $this->curItem[0] === $elm ) {
 589                         array_shift( $this->curItem );
 590                         array_shift( $this->mode );
 591                 }
 592         }
 593
 594         /**
 595          * Hit a closing element when in MODE_SIMPLE.
 596          * This generally means that we finished processing a
 597          * property value, and now have to save the result to the
 598          * results array
 599          *
 600          * For example, when processing:
 601          * <exif:DigitalZoomRatio>0/10</exif:DigitalZoomRatio>
 602          * this deals with when we hit </exif:DigitalZoomRatio>.
 603          *
 604          * Or it could be if we hit the end element of a property
 605          * of a compound data structure (like a member of an array).
 606          *
 607          * @param string $elm Namespace, space, and tag name.
 608          */
 609         private function endElementModeSimple( $elm ) {
 610                 if ( $this->charContent !== false ) {
 611                         if ( $this->processingArray ) {
 612                                 // if we're processing an array, use the original element
 613                                 // name instead of rdf:li.
 614                                 list( $ns, $tag ) = explode( ' ', $this->curItem[0], 2 );
 615                         } else {
 616                                 list( $ns, $tag ) = explode( ' ', $elm, 2 );
 617                         }
 618                         $this->saveValue( $ns, $tag, $this->charContent );
 619
 620                         $this->charContent = false; // reset
 621                 }
 622                 array_shift( $this->curItem );
 623                 array_shift( $this->mode );
 624         }
 625
 626         /**
 627          * Hit a closing element in MODE_STRUCT, MODE_SEQ, MODE_BAG
 628          * generally means we've finished processing a nested structure.
 629          * resets some internal variables to indicate that.
 630          *
 631          * Note this means we hit the closing element not the "</rdf:Seq>".
 632          *
 633          * @par For example, when processing:
 634          * @code{,xml}
 635          * <exif:ISOSpeedRatings> <rdf:Seq> <rdf:li>64</rdf:li>
 636          *   </rdf:Seq> </exif:ISOSpeedRatings>
 637          * @endcode
 638          *
 639          * This method is called when we hit the "</exif:ISOSpeedRatings>" tag.
 640          *
 641          * @param string $elm Namespace . space . tag name.
 642          * @throws RuntimeException
 643          */
 644         private function endElementNested( $elm ) {
 645                 /* cur item must be the same as $elm, unless if in MODE_STRUCT
 646                  * in which case it could also be rdf:Description */
 647                 if ( $this->curItem[0] !== $elm
 648                         && !( $elm === self::NS_RDF . ' Description'
 649                                 && $this->mode[0] === self::MODE_STRUCT )
 650                 ) {
 651                         throw new RuntimeException( "nesting mismatch. got a </$elm> but expected a </" .
 652                                 $this->curItem[0] . '>' );
 653                 }
 654
 655                 // Validate structures.
 656                 list( $ns, $tag ) = explode( ' ', $elm, 2 );
 657                 if ( isset( $this->items[$ns][$tag]['validate'] ) ) {
 658                         $info =& $this->items[$ns][$tag];
 659                         $finalName = isset( $info['map_name'] )
 660                                 ? $info['map_name'] : $tag;
 661
 662                         if ( is_array( $info['validate'] ) ) {
 663                                 $validate = $info['validate'];
 664                         } else {
 665                                 $validator = new XMPValidate( $this->logger );
 666                                 $validate = [ $validator, $info['validate'] ];
 667                         }
 668
 669                         if ( !isset( $this->results['xmp-' . $info['map_group']][$finalName] ) ) {
 670                                 // This can happen if all the members of the struct failed validation.
 671                                 $this->logger->debug( __METHOD__ . " <$ns:$tag> has no valid members." );
 672                         } elseif ( is_callable( $validate ) ) {
 673                                 $val =& $this->results['xmp-' . $info['map_group']][$finalName];
 674                                 call_user_func_array( $validate, [ $info, &$val, false ] );
 675                                 if ( is_null( $val ) ) {
 676                                         // the idea being the validation function will unset the variable if
 677                                         // its invalid.
 678                                         $this->logger->info( __METHOD__ . " <$ns:$tag> failed validation." );
 679                                         unset( $this->results['xmp-' . $info['map_group']][$finalName] );
 680                                 }
 681                         } else {
 682                                 $this->logger->warning( __METHOD__ . " Validation function for $finalName ("
 683                                         . $validate[0] . '::' . $validate[1] . '()) is not callable.' );
 684                         }
 685                 }
 686
 687                 array_shift( $this->curItem );
 688                 array_shift( $this->mode );
 689                 $this->ancestorStruct = false;
 690                 $this->processingArray = false;
 691                 $this->itemLang = false;
 692         }
 693
 694         /**
 695          * Hit a closing element in MODE_LI (either rdf:Seq, or rdf:Bag )
 696          * Add information about what type of element this is.
 697          *
 698          * Note we still have to hit the outer "</property>"
 699          *
 700          * @par For example, when processing:
 701          * @code{,xml}
 702          * <exif:ISOSpeedRatings> <rdf:Seq> <rdf:li>64</rdf:li>
 703          *   </rdf:Seq> </exif:ISOSpeedRatings>
 704          * @endcode
 705          *
 706          * This method is called when we hit the "</rdf:Seq>".
 707          * (For comparison, we call endElementModeSimple when we
 708          * hit the "</rdf:li>")
 709          *
 710          * @param string $elm Namespace . ' ' . element name
 711          * @throws RuntimeException
 712          */
 713         private function endElementModeLi( $elm ) {
 714                 list( $ns, $tag ) = explode( ' ', $this->curItem[0], 2 );
 715                 $info = $this->items[$ns][$tag];
 716                 $finalName = isset( $info['map_name'] )
 717                         ? $info['map_name'] : $tag;
 718
 719                 array_shift( $this->mode );
 720
 721                 if ( !isset( $this->results['xmp-' . $info['map_group']][$finalName] ) ) {
 722                         $this->logger->debug( __METHOD__ . " Empty compund element $finalName." );
 723
 724                         return;
 725                 }
 726
 727                 if ( $elm === self::NS_RDF . ' Seq' ) {
 728                         $this->results['xmp-' . $info['map_group']][$finalName]['_type'] = 'ol';
 729                 } elseif ( $elm === self::NS_RDF . ' Bag' ) {
 730                         $this->results['xmp-' . $info['map_group']][$finalName]['_type'] = 'ul';
 731                 } elseif ( $elm === self::NS_RDF . ' Alt' ) {
 732                         // extra if needed as you could theoretically have a non-language alt.
 733                         if ( $info['mode'] === self::MODE_LANG ) {
 734                                 $this->results['xmp-' . $info['map_group']][$finalName]['_type'] = 'lang';
 735                         }
 736                 } else {
 737                         throw new RuntimeException(
 738                                 __METHOD__ . " expected </rdf:seq> or </rdf:bag> but instead got $elm."
 739                         );
 740                 }
 741         }
 742
 743         /**
 744          * End element while in MODE_QDESC
 745          * mostly when ending an element when we have a simple value
 746          * that has qualifiers.
 747          *
 748          * Qualifiers aren't all that common, and we don't do anything
 749          * with them.
 750          *
 751          * @param string $elm Namespace and element
 752          */
 753         private function endElementModeQDesc( $elm ) {
 754                 if ( $elm === self::NS_RDF . ' value' ) {
 755                         list( $ns, $tag ) = explode( ' ', $this->curItem[0], 2 );
 756                         $this->saveValue( $ns, $tag, $this->charContent );
 757
 758                         return;
 759                 } else {
 760                         array_shift( $this->mode );
 761                         array_shift( $this->curItem );
 762                 }
 763         }
 764
 765         /**
 766          * Handler for hitting a closing element.
 767          *
 768          * generally just calls a helper function depending on what
 769          * mode we're in.
 770          *
 771          * Ignores the outer wrapping elements that are optional in
 772          * xmp and have no meaning.
 773          *
 774          * @param resource $parser
 775          * @param string $elm Namespace . ' ' . element name
 776          * @throws RuntimeException
 777          */
 778         function endElement( $parser, $elm ) {
 779                 if ( $elm === ( self::NS_RDF . ' RDF' )
 780                         || $elm === 'adobe:ns:meta/ xmpmeta'
 781                         || $elm === 'adobe:ns:meta/ xapmeta'
 782                 ) {
 783                         // ignore these.
 784                         return;
 785                 }
 786
 787                 if ( $elm === self::NS_RDF . ' type' ) {
 788                         // these aren't really supported properly yet.
 789                         // However, it appears they almost never used.
 790                         $this->logger->info( __METHOD__ . ' encountered <rdf:type>' );
 791                 }
 792
 793                 if ( strpos( $elm, ' ' ) === false ) {
 794                         // This probably shouldn't happen.
 795                         // However, there is a bug in an adobe product
 796                         // that forgets the namespace on some things.
 797                         // (Luckily they are unimportant things).
 798                         $this->logger->info( __METHOD__ . " Encountered </$elm> which has no namespace. Skipping." );
 799
 800                         return;
 801                 }
 802
 803                 if ( count( $this->mode[0] ) === 0 ) {
 804                         // This should never ever happen and means
 805                         // there is a pretty major bug in this class.
 806                         throw new RuntimeException( 'Encountered end element with no mode' );
 807                 }
 808
 809                 if ( count( $this->curItem ) == 0 && $this->mode[0] !== self::MODE_INITIAL ) {
 810                         // just to be paranoid. Should always have a curItem, except for initially
 811                         // (aka during MODE_INITAL).
 812                         throw new RuntimeException( "Hit end element </$elm> but no curItem" );
 813                 }
 814
 815                 switch ( $this->mode[0] ) {
 816                         case self::MODE_IGNORE:
 817                                 $this->endElementModeIgnore( $elm );
 818                                 break;
 819                         case self::MODE_SIMPLE:
 820                                 $this->endElementModeSimple( $elm );
 821                                 break;
 822                         case self::MODE_STRUCT:
 823                         case self::MODE_SEQ:
 824                         case self::MODE_BAG:
 825                         case self::MODE_LANG:
 826                         case self::MODE_BAGSTRUCT:
 827                                 $this->endElementNested( $elm );
 828                                 break;
 829                         case self::MODE_INITIAL:
 830                                 if ( $elm === self::NS_RDF . ' Description' ) {
 831                                         array_shift( $this->mode );
 832                                 } else {
 833                                         throw new RuntimeException( 'Element ended unexpectedly while in MODE_INITIAL' );
 834                                 }
 835                                 break;
 836                         case self::MODE_LI:
 837                         case self::MODE_LI_LANG:
 838                                 $this->endElementModeLi( $elm );
 839                                 break;
 840                         case self::MODE_QDESC:
 841                                 $this->endElementModeQDesc( $elm );
 842                                 break;
 843                         default:
 844                                 $this->logger->warning( __METHOD__ . " no mode (elm = $elm)" );
 845                                 break;
 846                 }
 847         }
 848
 849         /**
 850          * Hit an opening element while in MODE_IGNORE
 851          *
 852          * XMP is extensible, so ignore any tag we don't understand.
 853          *
 854          * Mostly ignores, unless we encounter the element that we are ignoring.
 855          * in which case we add it to the item stack, so we can ignore things
 856          * that are nested, correctly.
 857          *
 858          * @param string $elm Namespace . ' ' . tag name
 859          */
 860         private function startElementModeIgnore( $elm ) {
 861                 if ( $elm === $this->curItem[0] ) {
 862                         array_unshift( $this->curItem, $elm );
 863                         array_unshift( $this->mode, self::MODE_IGNORE );
 864                 }
 865         }
 866
 867         /**
 868          *  Start element in MODE_BAG (unordered array)
 869          * this should always be <rdf:Bag>
 870          *
 871          * @param string $elm Namespace . ' ' . tag
 872          * @throws RuntimeException If we have an element that's not <rdf:Bag>
 873          */
 874         private function startElementModeBag( $elm ) {
 875                 if ( $elm === self::NS_RDF . ' Bag' ) {
 876                         array_unshift( $this->mode, self::MODE_LI );
 877                 } else {
 878                         throw new RuntimeException( "Expected <rdf:Bag> but got $elm." );
 879                 }
 880         }
 881
 882         /**
 883          * Start element in MODE_SEQ (ordered array)
 884          * this should always be <rdf:Seq>
 885          *
 886          * @param string $elm Namespace . ' ' . tag
 887          * @throws RuntimeException If we have an element that's not <rdf:Seq>
 888          */
 889         private function startElementModeSeq( $elm ) {
 890                 if ( $elm === self::NS_RDF . ' Seq' ) {
 891                         array_unshift( $this->mode, self::MODE_LI );
 892                 } elseif ( $elm === self::NS_RDF . ' Bag' ) {
 893                         # T29105
 894                         $this->logger->info( __METHOD__ . ' Expected an rdf:Seq, but got an rdf:Bag. Pretending'
 895                                 . ' it is a Seq, since some buggy software is known to screw this up.' );
 896                         array_unshift( $this->mode, self::MODE_LI );
 897                 } else {
 898                         throw new RuntimeException( "Expected <rdf:Seq> but got $elm." );
 899                 }
 900         }
 901
 902         /**
 903          * Start element in MODE_LANG (language alternative)
 904          * this should always be <rdf:Alt>
 905          *
 906          * This tag tends to be used for metadata like describe this
 907          * picture, which can be translated into multiple languages.
 908          *
 909          * XMP supports non-linguistic alternative selections,
 910          * which are really only used for thumbnails, which
 911          * we don't care about.
 912          *
 913          * @param string $elm Namespace . ' ' . tag
 914          * @throws RuntimeException If we have an element that's not <rdf:Alt>
 915          */
 916         private function startElementModeLang( $elm ) {
 917                 if ( $elm === self::NS_RDF . ' Alt' ) {
 918                         array_unshift( $this->mode, self::MODE_LI_LANG );
 919                 } else {
 920                         throw new RuntimeException( "Expected <rdf:Seq> but got $elm." );
 921                 }
 922         }
 923
 924         /**
 925          * Handle an opening element when in MODE_SIMPLE
 926          *
 927          * This should not happen often. This is for if a simple element
 928          * already opened has a child element. Could happen for a
 929          * qualified element.
 930          *
 931          * For example:
 932          * <exif:DigitalZoomRatio><rdf:Description><rdf:value>0/10</rdf:value>
 933          *   <foo:someQualifier>Bar</foo:someQualifier> </rdf:Description>
 934          *   </exif:DigitalZoomRatio>
 935          *
 936          * This method is called when processing the <rdf:Description> element
 937          *
 938          * @param string $elm Namespace and tag names separated by space.
 939          * @param array $attribs Attributes of the element.
 940          * @throws RuntimeException
 941          */
 942         private function startElementModeSimple( $elm, $attribs ) {
 943                 if ( $elm === self::NS_RDF . ' Description' ) {
 944                         // If this value has qualifiers
 945                         array_unshift( $this->mode, self::MODE_QDESC );
 946                         array_unshift( $this->curItem, $this->curItem[0] );
 947
 948                         if ( isset( $attribs[self::NS_RDF . ' value'] ) ) {
 949                                 list( $ns, $tag ) = explode( ' ', $this->curItem[0], 2 );
 950                                 $this->saveValue( $ns, $tag, $attribs[self::NS_RDF . ' value'] );
 951                         }
 952                 } elseif ( $elm === self::NS_RDF . ' value' ) {
 953                         // This should not be here.
 954                         throw new RuntimeException( __METHOD__ . ' Encountered <rdf:value> where it was unexpected.' );
 955                 } else {
 956                         // something else we don't recognize, like a qualifier maybe.
 957                         $this->logger->info( __METHOD__ .
 958                                 " Encountered element <{element}> where only expecting character data as value of {curitem}",
 959                                 [ 'element' => $elm, 'curitem' => $this->curItem[0] ] );
 960                         array_unshift( $this->mode, self::MODE_IGNORE );
 961                         array_unshift( $this->curItem, $elm );
 962                 }
 963         }
 964
 965         /**
 966          * Start an element when in MODE_QDESC.
 967          * This generally happens when a simple element has an inner
 968          * rdf:Description to hold qualifier elements.
 969          *
 970          * For example in:
 971          * <exif:DigitalZoomRatio><rdf:Description><rdf:value>0/10</rdf:value>
 972          *   <foo:someQualifier>Bar</foo:someQualifier> </rdf:Description>
 973          *   </exif:DigitalZoomRatio>
 974          * Called when processing the <rdf:value> or <foo:someQualifier>.
 975          *
 976          * @param string $elm Namespace and tag name separated by a space.
 977          */
 978         private function startElementModeQDesc( $elm ) {
 979                 if ( $elm === self::NS_RDF . ' value' ) {
 980                         return; // do nothing
 981                 } else {
 982                         // otherwise its a qualifier, which we ignore
 983                         array_unshift( $this->mode, self::MODE_IGNORE );
 984                         array_unshift( $this->curItem, $elm );
 985                 }
 986         }
 987
 988         /**
 989          * Starting an element when in MODE_INITIAL
 990          * This usually happens when we hit an element inside
 991          * the outer rdf:Description
 992          *
 993          * This is generally where most properties start.
 994          *
 995          * @param string $ns Namespace
 996          * @param string $tag Tag name (without namespace prefix)
 997          * @param array $attribs Array of attributes
 998          * @throws RuntimeException
 999          */
1000         private function startElementModeInitial( $ns, $tag, $attribs ) {
1001                 if ( $ns !== self::NS_RDF ) {
1002                         if ( isset( $this->items[$ns][$tag] ) ) {
1003                                 if ( isset( $this->items[$ns][$tag]['structPart'] ) ) {
1004                                         // If this element is supposed to appear only as
1005                                         // a child of a structure, but appears here (not as
1006                                         // a child of a struct), then something weird is
1007                                         // happening, so ignore this element and its children.
1008
1009                                         $this->logger->warning(
1010                                                 'Encountered <{element}> outside of its expected parent. Ignoring.',
1011                                                 [ 'element' => "$ns:$tag" ]
1012                                         );
1013
1014                                         array_unshift( $this->mode, self::MODE_IGNORE );
1015                                         array_unshift( $this->curItem, $ns . ' ' . $tag );
1016
1017                                         return;
1018                                 }
1019                                 $mode = $this->items[$ns][$tag]['mode'];
1020                                 array_unshift( $this->mode, $mode );
1021                                 array_unshift( $this->curItem, $ns . ' ' . $tag );
1022                                 if ( $mode === self::MODE_STRUCT ) {
1023                                         $this->ancestorStruct = isset( $this->items[$ns][$tag]['map_name'] )
1024                                                 ? $this->items[$ns][$tag]['map_name'] : $tag;
1025                                 }
1026                                 if ( $this->charContent !== false ) {
1027                                         // Something weird.
1028                                         // Should not happen in valid XMP.
1029                                         throw new RuntimeException( 'tag nested in non-whitespace characters.' );
1030                                 }
1031                         } else {
1032                                 // This element is not on our list of allowed elements so ignore.
1033                                 $this->logger->debug( __METHOD__ . ' Ignoring unrecognized element <{element}>.',
1034                                         [ 'element' => "$ns:$tag" ] );
1035                                 array_unshift( $this->mode, self::MODE_IGNORE );
1036                                 array_unshift( $this->curItem, $ns . ' ' . $tag );
1037
1038                                 return;
1039                         }
1040                 }
1041                 // process attributes
1042                 $this->doAttribs( $attribs );
1043         }
1044
1045         /**
1046          * Hit an opening element when in a Struct (MODE_STRUCT)
1047          * This is generally for fields of a compound property.
1048          *
1049          * Example of a struct (abbreviated; flash has more properties):
1050          *
1051          * <exif:Flash> <rdf:Description> <exif:Fired>True</exif:Fired>
1052          *  <exif:Mode>1</exif:Mode></rdf:Description></exif:Flash>
1053          *
1054          * or:
1055          *
1056          * <exif:Flash rdf:parseType='Resource'> <exif:Fired>True</exif:Fired>
1057          *  <exif:Mode>1</exif:Mode></exif:Flash>
1058          *
1059          * @param string $ns Namespace
1060          * @param string $tag Tag name (no ns)
1061          * @param array $attribs Array of attribs w/ values.
1062          * @throws RuntimeException
1063          */
1064         private function startElementModeStruct( $ns, $tag, $attribs ) {
1065                 if ( $ns !== self::NS_RDF ) {
1066                         if ( isset( $this->items[$ns][$tag] ) ) {
1067                                 if ( isset( $this->items[$ns][$this->ancestorStruct]['children'] )
1068                                         && !isset( $this->items[$ns][$this->ancestorStruct]['children'][$tag] )
1069                                 ) {
1070                                         // This assumes that we don't have inter-namespace nesting
1071                                         // which we don't in all the properties we're interested in.
1072                                         throw new RuntimeException( " <$tag> appeared nested in <" . $this->ancestorStruct
1073                                                 . "> where it is not allowed." );
1074                                 }
1075                                 array_unshift( $this->mode, $this->items[$ns][$tag]['mode'] );
1076                                 array_unshift( $this->curItem, $ns . ' ' . $tag );
1077                                 if ( $this->charContent !== false ) {
1078                                         // Something weird.
1079                                         // Should not happen in valid XMP.
1080                                         throw new RuntimeException( "tag <$tag> nested in non-whitespace characters (" .
1081                                                 $this->charContent . ")." );
1082                                 }
1083                         } else {
1084                                 array_unshift( $this->mode, self::MODE_IGNORE );
1085                                 array_unshift( $this->curItem, $ns . ' ' . $tag );
1086
1087                                 return;
1088                         }
1089                 }
1090
1091                 if ( $ns === self::NS_RDF && $tag === 'Description' ) {
1092                         $this->doAttribs( $attribs );
1093                         array_unshift( $this->mode, self::MODE_STRUCT );
1094                         array_unshift( $this->curItem, $this->curItem[0] );
1095                 }
1096         }
1097
1098         /**
1099          * opening element in MODE_LI
1100          * process elements of arrays.
1101          *
1102          * Example:
1103          * <exif:ISOSpeedRatings> <rdf:Seq> <rdf:li>64</rdf:li>
1104          *   </rdf:Seq> </exif:ISOSpeedRatings>
1105          * This method is called when we hit the <rdf:li> element.
1106          *
1107          * @param string $elm Namespace . ' ' . tagname
1108          * @param array $attribs Attributes. (needed for BAGSTRUCTS)
1109          * @throws RuntimeException If gets a tag other than <rdf:li>
1110          */
1111         private function startElementModeLi( $elm, $attribs ) {
1112                 if ( ( $elm ) !== self::NS_RDF . ' li' ) {
1113                         throw new RuntimeException( "<rdf:li> expected but got $elm." );
1114                 }
1115
1116                 if ( !isset( $this->mode[1] ) ) {
1117                         // This should never ever ever happen. Checking for it
1118                         // to be paranoid.
1119                         throw new RuntimeException( 'In mode Li, but no 2xPrevious mode!' );
1120                 }
1121
1122                 if ( $this->mode[1] === self::MODE_BAGSTRUCT ) {
1123                         // This list item contains a compound (STRUCT) value.
1124                         array_unshift( $this->mode, self::MODE_STRUCT );
1125                         array_unshift( $this->curItem, $elm );
1126                         $this->processingArray = true;
1127
1128                         if ( !isset( $this->curItem[1] ) ) {
1129                                 // be paranoid.
1130                                 throw new RuntimeException( 'Can not find parent of BAGSTRUCT.' );
1131                         }
1132                         list( $curNS, $curTag ) = explode( ' ', $this->curItem[1] );
1133                         $this->ancestorStruct = isset( $this->items[$curNS][$curTag]['map_name'] )
1134                                 ? $this->items[$curNS][$curTag]['map_name'] : $curTag;
1135
1136                         $this->doAttribs( $attribs );
1137                 } else {
1138                         // Normal BAG or SEQ containing simple values.
1139                         array_unshift( $this->mode, self::MODE_SIMPLE );
1140                         // need to add curItem[0] on again since one is for the specific item
1141                         // and one is for the entire group.
1142                         array_unshift( $this->curItem, $this->curItem[0] );
1143                         $this->processingArray = true;
1144                 }
1145         }
1146
1147         /**
1148          * Opening element in MODE_LI_LANG.
1149          * process elements of language alternatives
1150          *
1151          * Example:
1152          * <dc:title> <rdf:Alt> <rdf:li xml:lang="x-default">My house
1153          *  </rdf:li> </rdf:Alt> </dc:title>
1154          *
1155          * This method is called when we hit the <rdf:li> element.
1156          *
1157          * @param string $elm Namespace . ' ' . tag
1158          * @param array $attribs Array of elements (most importantly xml:lang)
1159          * @throws RuntimeException If gets a tag other than <rdf:li> or if no xml:lang
1160          */
1161         private function startElementModeLiLang( $elm, $attribs ) {
1162                 if ( $elm !== self::NS_RDF . ' li' ) {
1163                         throw new RuntimeException( __METHOD__ . " <rdf:li> expected but got $elm." );
1164                 }
1165                 if ( !isset( $attribs[self::NS_XML . ' lang'] )
1166                         || !preg_match( '/^[-A-Za-z0-9]{2,}$/D', $attribs[self::NS_XML . ' lang'] )
1167                 ) {
1168                         throw new RuntimeException( __METHOD__
1169                                 . " <rdf:li> did not contain, or has invalid xml:lang attribute in lang alternative" );
1170                 }
1171
1172                 // Lang is case-insensitive.
1173                 $this->itemLang = strtolower( $attribs[self::NS_XML . ' lang'] );
1174
1175                 // need to add curItem[0] on again since one is for the specific item
1176                 // and one is for the entire group.
1177                 array_unshift( $this->curItem, $this->curItem[0] );
1178                 array_unshift( $this->mode, self::MODE_SIMPLE );
1179                 $this->processingArray = true;
1180         }
1181
1182         /**
1183          * Hits an opening element.
1184          * Generally just calls a helper based on what MODE we're in.
1185          * Also does some initial set up for the wrapper element
1186          *
1187          * @param resource $parser
1188          * @param string $elm Namespace "<space>" element
1189          * @param array $attribs Attribute name => value
1190          * @throws RuntimeException
1191          */
1192         function startElement( $parser, $elm, $attribs ) {
1193                 if ( $elm === self::NS_RDF . ' RDF'
1194                         || $elm === 'adobe:ns:meta/ xmpmeta'
1195                         || $elm === 'adobe:ns:meta/ xapmeta'
1196                 ) {
1197                         /* ignore. */
1198                         return;
1199                 } elseif ( $elm === self::NS_RDF . ' Description' ) {
1200                         if ( count( $this->mode ) === 0 ) {
1201                                 // outer rdf:desc
1202                                 array_unshift( $this->mode, self::MODE_INITIAL );
1203                         }
1204                 } elseif ( $elm === self::NS_RDF . ' type' ) {
1205                         // This doesn't support rdf:type properly.
1206                         // In practise I have yet to see a file that
1207                         // uses this element, however it is mentioned
1208                         // on page 25 of part 1 of the xmp standard.
1209                         // Also it seems as if exiv2 and exiftool do not support
1210                         // this either (That or I misunderstand the standard)
1211                         $this->logger->info( __METHOD__ . ' Encountered <rdf:type> which isn\'t currently supported' );
1212                 }
1213
1214                 if ( strpos( $elm, ' ' ) === false ) {
1215                         // This probably shouldn't happen.
1216                         $this->logger->info( __METHOD__ . " Encountered <$elm> which has no namespace. Skipping." );
1217
1218                         return;
1219                 }
1220
1221                 list( $ns, $tag ) = explode( ' ', $elm, 2 );
1222
1223                 if ( count( $this->mode ) === 0 ) {
1224                         // This should not happen.
1225                         throw new RuntimeException( 'Error extracting XMP, '
1226                                 . "encountered <$elm> with no mode" );
1227                 }
1228
1229                 switch ( $this->mode[0] ) {
1230                         case self::MODE_IGNORE:
1231                                 $this->startElementModeIgnore( $elm );
1232                                 break;
1233                         case self::MODE_SIMPLE:
1234                                 $this->startElementModeSimple( $elm, $attribs );
1235                                 break;
1236                         case self::MODE_INITIAL:
1237                                 $this->startElementModeInitial( $ns, $tag, $attribs );
1238                                 break;
1239                         case self::MODE_STRUCT:
1240                                 $this->startElementModeStruct( $ns, $tag, $attribs );
1241                                 break;
1242                         case self::MODE_BAG:
1243                         case self::MODE_BAGSTRUCT:
1244                                 $this->startElementModeBag( $elm );
1245                                 break;
1246                         case self::MODE_SEQ:
1247                                 $this->startElementModeSeq( $elm );
1248                                 break;
1249                         case self::MODE_LANG:
1250                                 $this->startElementModeLang( $elm );
1251                                 break;
1252                         case self::MODE_LI_LANG:
1253                                 $this->startElementModeLiLang( $elm, $attribs );
1254                                 break;
1255                         case self::MODE_LI:
1256                                 $this->startElementModeLi( $elm, $attribs );
1257                                 break;
1258                         case self::MODE_QDESC:
1259                                 $this->startElementModeQDesc( $elm );
1260                                 break;
1261                         default:
1262                                 throw new RuntimeException( 'StartElement in unknown mode: ' . $this->mode[0] );
1263                 }
1264         }
1265
1266         // @codingStandardsIgnoreStart Generic.Files.LineLength
1267         /**
1268          * Process attributes.
1269          * Simple values can be stored as either a tag or attribute
1270          *
1271          * Often the initial "<rdf:Description>" tag just has all the simple
1272          * properties as attributes.
1273          *
1274          * @par Example:
1275          * @code
1276          * <rdf:Description rdf:about="" xmlns:exif="http://ns.adobe.com/exif/1.0/" exif:DigitalZoomRatio="0/10">
1277          * @endcode
1278          *
1279          * @param array $attribs Array attribute=>value
1280          * @throws RuntimeException
1281          */
1282         // @codingStandardsIgnoreEnd
1283         private function doAttribs( $attribs ) {
1284                 // first check for rdf:parseType attribute, as that can change
1285                 // how the attributes are interperted.
1286
1287                 if ( isset( $attribs[self::NS_RDF . ' parseType'] )
1288                         && $attribs[self::NS_RDF . ' parseType'] === 'Resource'
1289                         && $this->mode[0] === self::MODE_SIMPLE
1290                 ) {
1291                         // this is equivalent to having an inner rdf:Description
1292                         $this->mode[0] = self::MODE_QDESC;
1293                 }
1294                 foreach ( $attribs as $name => $val ) {
1295                         if ( strpos( $name, ' ' ) === false ) {
1296                                 // This shouldn't happen, but so far some old software forgets namespace
1297                                 // on rdf:about.
1298                                 $this->logger->info( __METHOD__ . ' Encountered non-namespaced attribute: '
1299                                         . " $name=\"$val\". Skipping. " );
1300                                 continue;
1301                         }
1302                         list( $ns, $tag ) = explode( ' ', $name, 2 );
1303                         if ( $ns === self::NS_RDF ) {
1304                                 if ( $tag === 'value' || $tag === 'resource' ) {
1305                                         // resource is for url.
1306                                         // value attribute is a weird way of just putting the contents.
1307                                         $this->char( $this->xmlParser, $val );
1308                                 }
1309                         } elseif ( isset( $this->items[$ns][$tag] ) ) {
1310                                 if ( $this->mode[0] === self::MODE_SIMPLE ) {
1311                                         throw new RuntimeException( __METHOD__
1312                                                 . " $ns:$tag found as attribute where not allowed" );
1313                                 }
1314                                 $this->saveValue( $ns, $tag, $val );
1315                         } else {
1316                                 $this->logger->debug( __METHOD__ . " Ignoring unrecognized element <$ns:$tag>." );
1317                         }
1318                 }
1319         }
1320
1321         /**
1322          * Given an extracted value, save it to results array
1323          *
1324          * note also uses $this->ancestorStruct and
1325          * $this->processingArray to determine what name to
1326          * save the value under. (in addition to $tag).
1327          *
1328          * @param string $ns Namespace of tag this is for
1329          * @param string $tag Tag name
1330          * @param string $val Value to save
1331          */
1332         private function saveValue( $ns, $tag, $val ) {
1333                 $info =& $this->items[$ns][$tag];
1334                 $finalName = isset( $info['map_name'] )
1335                         ? $info['map_name'] : $tag;
1336                 if ( isset( $info['validate'] ) ) {
1337                         if ( is_array( $info['validate'] ) ) {
1338                                 $validate = $info['validate'];
1339                         } else {
1340                                 $validator = new XMPValidate( $this->logger );
1341                                 $validate = [ $validator, $info['validate'] ];
1342                         }
1343
1344                         if ( is_callable( $validate ) ) {
1345                                 call_user_func_array( $validate, [ $info, &$val, true ] );
1346                                 // the reasoning behind using &$val instead of using the return value
1347                                 // is to be consistent between here and validating structures.
1348                                 if ( is_null( $val ) ) {
1349                                         $this->logger->info( __METHOD__ . " <$ns:$tag> failed validation." );
1350
1351                                         return;
1352                                 }
1353                         } else {
1354                                 $this->logger->warning( __METHOD__ . " Validation function for $finalName ("
1355                                         . $validate[0] . '::' . $validate[1] . '()) is not callable.' );
1356                         }
1357                 }
1358
1359                 if ( $this->ancestorStruct && $this->processingArray ) {
1360                         // Aka both an array and a struct. ( self::MODE_BAGSTRUCT )
1361                         $this->results['xmp-' . $info['map_group']][$this->ancestorStruct][][$finalName] = $val;
1362                 } elseif ( $this->ancestorStruct ) {
1363                         $this->results['xmp-' . $info['map_group']][$this->ancestorStruct][$finalName] = $val;
1364                 } elseif ( $this->processingArray ) {
1365                         if ( $this->itemLang === false ) {
1366                                 // normal array
1367                                 $this->results['xmp-' . $info['map_group']][$finalName][] = $val;
1368                         } else {
1369                                 // lang array.
1370                                 $this->results['xmp-' . $info['map_group']][$finalName][$this->itemLang] = $val;
1371                         }
1372                 } else {
1373                         $this->results['xmp-' . $info['map_group']][$finalName] = $val;
1374                 }
1375         }
1376 }