includes/media/XMP.php

   1 <?php
   2 /**
   3  * Reader for XMP data containing properties relevant to images.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Media
  22  */
  23
  24 use Psr\Log\LoggerAwareInterface;
  25 use Psr\Log\LoggerInterface;
  26 use Psr\Log\NullLogger;
  27
  28 /**
  29  * Class for reading xmp data containing properties relevant to
  30  * images, and spitting out an array that FormatMetadata accepts.
  31  *
  32  * Note, this is not meant to recognize every possible thing you can
  33  * encode in XMP. It should recognize all the properties we want.
  34  * For example it doesn't have support for structures with multiple
  35  * nesting levels, as none of the properties we're supporting use that
  36  * feature. If it comes across properties it doesn't recognize, it should
  37  * ignore them.
  38  *
  39  * The public methods one would call in this class are
  40  * - parse( $content )
  41  *    Reads in xmp content.
  42  *    Can potentially be called multiple times with partial data each time.
  43  * - parseExtended( $content )
  44  *    Reads XMPExtended blocks (jpeg files only).
  45  * - getResults
  46  *    Outputs a results array.
  47  *
  48  * Note XMP kind of looks like rdf. They are not the same thing - XMP is
  49  * encoded as a specific subset of rdf. This class can read XMP. It cannot
  50  * read rdf.
  51  *
  52  */
  53 class XMPReader implements LoggerAwareInterface {
  54         /** @var array XMP item configuration array */
  55         protected $items;
  56
  57         /** @var array Array to hold the current element (and previous element, and so on) */
  58         private $curItem = array();
  59
  60         /** @var bool|string The structure name when processing nested structures. */
  61         private $ancestorStruct = false;
  62
  63         /** @var bool|string Temporary holder for character data that appears in xmp doc. */
  64         private $charContent = false;
  65
  66         /** @var array Stores the state the xmpreader is in (see MODE_FOO constants) */
  67         private $mode = array();
  68
  69         /** @var array Array to hold results */
  70         private $results = array();
  71
  72         /** @var bool If we're doing a seq or bag. */
  73         private $processingArray = false;
  74
  75         /** @var bool|string Used for lang alts only */
  76         private $itemLang = false;
  77
  78         /** @var resource A resource handle for the XML parser */
  79         private $xmlParser;
  80
  81         /** @var bool|string Character set like 'UTF-8' */
  82         private $charset = false;
  83
  84         /** @var int */
  85         private $extendedXMPOffset = 0;
  86
  87         /** @var int Flag determining if the XMP is safe to parse **/
  88         private $parsable = 0;
  89
  90         /** @var string Buffer of XML to parse **/
  91         private $xmlParsableBuffer = '';
  92
  93         /**
  94          * These are various mode constants.
  95          * they are used to figure out what to do
  96          * with an element when its encountered.
  97          *
  98          * For example, MODE_IGNORE is used when processing
  99          * a property we're not interested in. So if a new
 100          * element pops up when we're in that mode, we ignore it.
 101          */
 102         const MODE_INITIAL = 0;
 103         const MODE_IGNORE = 1;
 104         const MODE_LI = 2;
 105         const MODE_LI_LANG = 3;
 106         const MODE_QDESC = 4;
 107
 108         // The following MODE constants are also used in the
 109         // $items array to denote what type of property the item is.
 110         const MODE_SIMPLE = 10;
 111         const MODE_STRUCT = 11; // structure (associative array)
 112         const MODE_SEQ = 12; // ordered list
 113         const MODE_BAG = 13; // unordered list
 114         const MODE_LANG = 14;
 115         const MODE_ALT = 15; // non-language alt. Currently not implemented, and not needed atm.
 116         const MODE_BAGSTRUCT = 16; // A BAG of Structs.
 117
 118         const NS_RDF = 'http://www.w3.org/1999/02/22-rdf-syntax-ns#';
 119         const NS_XML = 'http://www.w3.org/XML/1998/namespace';
 120
 121         // States used while determining if XML is safe to parse
 122         const PARSABLE_UNKNOWN = 0;
 123         const PARSABLE_OK = 1;
 124         const PARSABLE_BUFFERING = 2;
 125         const PARSABLE_NO = 3;
 126
 127         /**
 128          * @var LoggerInterface
 129          */
 130         private $logger;
 131
 132         /**
 133          * Constructor.
 134          *
 135          * Primary job is to initialize the XMLParser
 136          */
 137         function __construct( LoggerInterface $logger = null ) {
 138
 139                 if ( !function_exists( 'xml_parser_create_ns' ) ) {
 140                         // this should already be checked by this point
 141                         throw new RuntimeException( 'XMP support requires XML Parser' );
 142                 }
 143                 if ( $logger ) {
 144                         $this->setLogger( $logger );
 145                 } else {
 146                         $this->setLogger( new NullLogger() );
 147                 }
 148
 149                 $this->items = XMPInfo::getItems();
 150
 151                 $this->resetXMLParser();
 152         }
 153
 154         public function setLogger( LoggerInterface $logger ) {
 155                 $this->logger = $logger;
 156         }
 157
 158         /**
 159          * Main use is if a single item has multiple xmp documents describing it.
 160          * For example in jpeg's with extendedXMP
 161          */
 162         private function resetXMLParser() {
 163
 164                 if ( $this->xmlParser ) {
 165                         //is this needed?
 166                         xml_parser_free( $this->xmlParser );
 167                 }
 168
 169                 $this->xmlParser = xml_parser_create_ns( 'UTF-8', ' ' );
 170                 xml_parser_set_option( $this->xmlParser, XML_OPTION_CASE_FOLDING, 0 );
 171                 xml_parser_set_option( $this->xmlParser, XML_OPTION_SKIP_WHITE, 1 );
 172
 173                 xml_set_element_handler( $this->xmlParser,
 174                         array( $this, 'startElement' ),
 175                         array( $this, 'endElement' ) );
 176
 177                 xml_set_character_data_handler( $this->xmlParser, array( $this, 'char' ) );
 178
 179                 $this->parsable = self::PARSABLE_UNKNOWN;
 180                 $this->xmlParsableBuffer = '';
 181         }
 182
 183         /** Destroy the xml parser
 184          *
 185          * Not sure if this is actually needed.
 186          */
 187         function __destruct() {
 188                 // not sure if this is needed.
 189                 xml_parser_free( $this->xmlParser );
 190         }
 191
 192         /**
 193          * Check if this instance supports using this class
 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
 274                         // Must convert to a real before multiplying by -1
 275                         // XMPValidate guarantees there will always be a '/' in this value.
 276                         list( $nom, $denom ) = explode( '/', $data['xmp-exif']['GPSAltitude'] );
 277                         $data['xmp-exif']['GPSAltitude'] = $nom / $denom;
 278
 279                         if ( $data['xmp-exif']['GPSAltitudeRef'] == '1' ) {
 280                                 $data['xmp-exif']['GPSAltitude'] *= -1;
 281                         }
 282                         unset( $data['xmp-exif']['GPSAltitudeRef'] );
 283                 }
 284
 285                 return $data;
 286         }
 287
 288         /**
 289          * Main function to call to parse XMP. Use getResults to
 290          * get results.
 291          *
 292          * Also catches any errors during processing, writes them to
 293          * debug log, blanks result array and returns false.
 294          *
 295          * @param string $content XMP data
 296          * @param bool $allOfIt If this is all the data (true) or if its split up (false). Default true
 297          * @param bool $reset Does xml parser need to be reset. Default false
 298          * @throws RuntimeException
 299          * @return bool Success.
 300          */
 301         public function parse( $content, $allOfIt = true, $reset = false ) {
 302                 if ( $reset ) {
 303                         $this->resetXMLParser();
 304                 }
 305                 try {
 306
 307                         // detect encoding by looking for BOM which is supposed to be in processing instruction.
 308                         // see page 12 of http://www.adobe.com/devnet/xmp/pdfs/XMPSpecificationPart3.pdf
 309                         if ( !$this->charset ) {
 310                                 $bom = array();
 311                                 if ( preg_match( '/\xEF\xBB\xBF|\xFE\xFF|\x00\x00\xFE\xFF|\xFF\xFE\x00\x00|\xFF\xFE/',
 312                                         $content, $bom )
 313                                 ) {
 314                                         switch ( $bom[0] ) {
 315                                                 case "\xFE\xFF":
 316                                                         $this->charset = 'UTF-16BE';
 317                                                         break;
 318                                                 case "\xFF\xFE":
 319                                                         $this->charset = 'UTF-16LE';
 320                                                         break;
 321                                                 case "\x00\x00\xFE\xFF":
 322                                                         $this->charset = 'UTF-32BE';
 323                                                         break;
 324                                                 case "\xFF\xFE\x00\x00":
 325                                                         $this->charset = 'UTF-32LE';
 326                                                         break;
 327                                                 case "\xEF\xBB\xBF":
 328                                                         $this->charset = 'UTF-8';
 329                                                         break;
 330                                                 default:
 331                                                         //this should be impossible to get to
 332                                                         throw new RuntimeException( "Invalid BOM" );
 333                                         }
 334                                 } else {
 335                                         // standard specifically says, if no bom assume utf-8
 336                                         $this->charset = 'UTF-8';
 337                                 }
 338                         }
 339                         if ( $this->charset !== 'UTF-8' ) {
 340                                 //don't convert if already utf-8
 341                                 wfSuppressWarnings();
 342                                 $content = iconv( $this->charset, 'UTF-8//IGNORE', $content );
 343                                 wfRestoreWarnings();
 344                         }
 345
 346                         // Ensure the XMP block does not have an xml doctype declaration, which
 347                         // could declare entities unsafe to parse with xml_parse (T85848/T71210).
 348                         if ( $this->parsable !== self::PARSABLE_OK ) {
 349                                 if ( $this->parsable === self::PARSABLE_NO ) {
 350                                         throw new Exception( 'Unsafe doctype declaration in XML.' );
 351                                 }
 352
 353                                 $content = $this->xmlParsableBuffer . $content;
 354                                 if ( !$this->checkParseSafety( $content ) ) {
 355                                         if ( !$allOfIt && $this->parsable !== self::PARSABLE_NO ) {
 356                                                 // parse wasn't Unsuccessful yet, so return true
 357                                                 // in this case.
 358                                                 return true;
 359                                         }
 360                                         $msg = ( $this->parsable === self::PARSABLE_NO ) ?
 361                                                 'Unsafe doctype declaration in XML.' :
 362                                                 'No root element found in XML.';
 363                                         throw new Exception( $msg );
 364                                 }
 365                         }
 366
 367                         $ok = xml_parse( $this->xmlParser, $content, $allOfIt );
 368                         if ( !$ok ) {
 369                                 $error = xml_error_string( xml_get_error_code( $this->xmlParser ) );
 370                                 $where = 'line: ' . xml_get_current_line_number( $this->xmlParser )
 371                                         . ' column: ' . xml_get_current_column_number( $this->xmlParser )
 372                                         . ' byte offset: ' . xml_get_current_byte_index( $this->xmlParser );
 373
 374                                 $this->logger->info( "XMPReader::parse : Error reading XMP content: $error ($where)" );
 375                                 $this->results = array(); // blank if error.
 376                                 return false;
 377                         }
 378                 } catch ( Exception $e ) {
 379                         $this->logger->info( 'XMP parse error: ' . $e );
 380                         $this->results = array();
 381
 382                         return false;
 383                 }
 384
 385                 return true;
 386         }
 387
 388         /** Entry point for XMPExtended blocks in jpeg files
 389          *
 390          * @todo In serious need of testing
 391          * @see http://www.adobe.ge/devnet/xmp/pdfs/XMPSpecificationPart3.pdf XMP spec part 3 page 20
 392          * @param string $content XMPExtended block minus the namespace signature
 393          * @return bool If it succeeded.
 394          */
 395         public function parseExtended( $content ) {
 396                 // @todo FIXME: This is untested. Hard to find example files
 397                 // or programs that make such files..
 398                 $guid = substr( $content, 0, 32 );
 399                 if ( !isset( $this->results['xmp-special']['HasExtendedXMP'] )
 400                         || $this->results['xmp-special']['HasExtendedXMP'] !== $guid
 401                 ) {
 402                         $this->logger->info( __METHOD__ .
 403                                 " Ignoring XMPExtended block due to wrong guid (guid= '$guid')" );
 404
 405                         return false;
 406                 }
 407                 $len = unpack( 'Nlength/Noffset', substr( $content, 32, 8 ) );
 408
 409                 if ( !$len || $len['length'] < 4 || $len['offset'] < 0 || $len['offset'] > $len['length'] ) {
 410                         $this->logger->info(  __METHOD__ . 'Error reading extended XMP block, invalid length or offset.' );
 411
 412                         return false;
 413                 }
 414
 415                 // we're not very robust here. we should accept it in the wrong order.
 416                 // To quote the XMP standard:
 417                 // "A JPEG writer should write the ExtendedXMP marker segments in order,
 418                 // immediately following the StandardXMP. However, the JPEG standard
 419                 // does not require preservation of marker segment order. A robust JPEG
 420                 // reader should tolerate the marker segments in any order."
 421                 //
 422                 // otoh the probability that an image will have more than 128k of
 423                 // metadata is rather low... so the probability that it will have
 424                 // > 128k, and be in the wrong order is very low...
 425
 426                 if ( $len['offset'] !== $this->extendedXMPOffset ) {
 427                         $this->logger->info( __METHOD__ . 'Ignoring XMPExtended block due to wrong order. (Offset was '
 428                                 . $len['offset'] . ' but expected ' . $this->extendedXMPOffset . ')' );
 429
 430                         return false;
 431                 }
 432
 433                 if ( $len['offset'] === 0 ) {
 434                         // if we're starting the extended block, we've probably already
 435                         // done the XMPStandard block, so reset.
 436                         $this->resetXMLParser();
 437                 }
 438
 439                 $this->extendedXMPOffset += $len['length'];
 440
 441                 $actualContent = substr( $content, 40 );
 442
 443                 if ( $this->extendedXMPOffset === strlen( $actualContent ) ) {
 444                         $atEnd = true;
 445                 } else {
 446                         $atEnd = false;
 447                 }
 448
 449                 $this->logger->debug( __METHOD__ . 'Parsing a XMPExtended block' );
 450
 451                 return $this->parse( $actualContent, $atEnd );
 452         }
 453
 454         /**
 455          * Character data handler
 456          * Called whenever character data is found in the xmp document.
 457          *
 458          * does nothing if we're in MODE_IGNORE or if the data is whitespace
 459          * throws an error if we're not in MODE_SIMPLE (as we're not allowed to have character
 460          * data in the other modes).
 461          *
 462          * As an example, this happens when we encounter XMP like:
 463          * <exif:DigitalZoomRatio>0/10</exif:DigitalZoomRatio>
 464          * and are processing the 0/10 bit.
 465          *
 466          * @param XMLParser $parser XMLParser reference to the xml parser
 467          * @param string $data Character data
 468          * @throws RuntimeException On invalid data
 469          */
 470         function char( $parser, $data ) {
 471
 472                 $data = trim( $data );
 473                 if ( trim( $data ) === "" ) {
 474                         return;
 475                 }
 476
 477                 if ( !isset( $this->mode[0] ) ) {
 478                         throw new RuntimeException( 'Unexpected character data before first rdf:Description element' );
 479                 }
 480
 481                 if ( $this->mode[0] === self::MODE_IGNORE ) {
 482                         return;
 483                 }
 484
 485                 if ( $this->mode[0] !== self::MODE_SIMPLE
 486                         && $this->mode[0] !== self::MODE_QDESC
 487                 ) {
 488                         throw new RuntimeException( 'character data where not expected. (mode ' . $this->mode[0] . ')' );
 489                 }
 490
 491                 // to check, how does this handle w.s.
 492                 if ( $this->charContent === false ) {
 493                         $this->charContent = $data;
 494                 } else {
 495                         $this->charContent .= $data;
 496                 }
 497         }
 498
 499         /**
 500          * Check if a block of XML is safe to pass to xml_parse, i.e. doesn't
 501          * contain a doctype declaration which could contain a dos attack if we
 502          * parse it and expand internal entities (T85848).
 503          *
 504          * @param string $content xml string to check for parse safety
 505          * @return bool true if the xml is safe to parse, false otherwise
 506          */
 507         private function checkParseSafety( $content ) {
 508                 $reader = new XMLReader();
 509                 $result = null;
 510
 511                 // For XMLReader to parse incomplete/invalid XML, it has to be open()'ed
 512                 // instead of using XML().
 513                 $reader->open(
 514                         'data://text/plain,' . urlencode( $content ),
 515                         null,
 516                         LIBXML_NOERROR | LIBXML_NOWARNING | LIBXML_NONET
 517                 );
 518
 519                 $oldDisable = libxml_disable_entity_loader( true );
 520                 $reset = new ScopedCallback(
 521                         'libxml_disable_entity_loader',
 522                         array( $oldDisable )
 523                 );
 524                 $reader->setParserProperty( XMLReader::SUBST_ENTITIES, false );
 525
 526                 // Even with LIBXML_NOWARNING set, XMLReader::read gives a warning
 527                 // when parsing truncated XML, which causes unit tests to fail.
 528                 wfSuppressWarnings();
 529                 while ( $reader->read() ) {
 530                         if ( $reader->nodeType === XMLReader::ELEMENT ) {
 531                                 // Reached the first element without hitting a doctype declaration
 532                                 $this->parsable = self::PARSABLE_OK;
 533                                 $result = true;
 534                                 break;
 535                         }
 536                         if ( $reader->nodeType === XMLReader::DOC_TYPE ) {
 537                                 $this->parsable = self::PARSABLE_NO;
 538                                 $result = false;
 539                                 break;
 540                         }
 541                 }
 542                 wfRestoreWarnings();
 543
 544                 if ( !is_null( $result ) ) {
 545                         return $result;
 546                 }
 547
 548                 // Reached the end of the parsable xml without finding an element
 549                 // or doctype. Buffer and try again.
 550                 $this->parsable = self::PARSABLE_BUFFERING;
 551                 $this->xmlParsableBuffer = $content;
 552                 return false;
 553         }
 554
 555         /** When we hit a closing element in MODE_IGNORE
 556          * Check to see if this is the element we started to ignore,
 557          * in which case we get out of MODE_IGNORE
 558          *
 559          * @param string $elm Namespace of element followed by a space and then tag name of element.
 560          */
 561         private function endElementModeIgnore( $elm ) {
 562                 if ( $this->curItem[0] === $elm ) {
 563                         array_shift( $this->curItem );
 564                         array_shift( $this->mode );
 565                 }
 566         }
 567
 568         /**
 569          * Hit a closing element when in MODE_SIMPLE.
 570          * This generally means that we finished processing a
 571          * property value, and now have to save the result to the
 572          * results array
 573          *
 574          * For example, when processing:
 575          * <exif:DigitalZoomRatio>0/10</exif:DigitalZoomRatio>
 576          * this deals with when we hit </exif:DigitalZoomRatio>.
 577          *
 578          * Or it could be if we hit the end element of a property
 579          * of a compound data structure (like a member of an array).
 580          *
 581          * @param string $elm Namespace, space, and tag name.
 582          */
 583         private function endElementModeSimple( $elm ) {
 584                 if ( $this->charContent !== false ) {
 585                         if ( $this->processingArray ) {
 586                                 // if we're processing an array, use the original element
 587                                 // name instead of rdf:li.
 588                                 list( $ns, $tag ) = explode( ' ', $this->curItem[0], 2 );
 589                         } else {
 590                                 list( $ns, $tag ) = explode( ' ', $elm, 2 );
 591                         }
 592                         $this->saveValue( $ns, $tag, $this->charContent );
 593
 594                         $this->charContent = false; // reset
 595                 }
 596                 array_shift( $this->curItem );
 597                 array_shift( $this->mode );
 598         }
 599
 600         /**
 601          * Hit a closing element in MODE_STRUCT, MODE_SEQ, MODE_BAG
 602          * generally means we've finished processing a nested structure.
 603          * resets some internal variables to indicate that.
 604          *
 605          * Note this means we hit the closing element not the "</rdf:Seq>".
 606          *
 607          * @par For example, when processing:
 608          * @code{,xml}
 609          * <exif:ISOSpeedRatings> <rdf:Seq> <rdf:li>64</rdf:li>
 610          *   </rdf:Seq> </exif:ISOSpeedRatings>
 611          * @endcode
 612          *
 613          * This method is called when we hit the "</exif:ISOSpeedRatings>" tag.
 614          *
 615          * @param string $elm Namespace . space . tag name.
 616          * @throws RuntimeException
 617          */
 618         private function endElementNested( $elm ) {
 619
 620                 /* cur item must be the same as $elm, unless if in MODE_STRUCT
 621                    in which case it could also be rdf:Description */
 622                 if ( $this->curItem[0] !== $elm
 623                         && !( $elm === self::NS_RDF . ' Description'
 624                                 && $this->mode[0] === self::MODE_STRUCT )
 625                 ) {
 626                         throw new RuntimeException( "nesting mismatch. got a </$elm> but expected a </" .
 627                                 $this->curItem[0] . '>' );
 628                 }
 629
 630                 // Validate structures.
 631                 list( $ns, $tag ) = explode( ' ', $elm, 2 );
 632                 if ( isset( $this->items[$ns][$tag]['validate'] ) ) {
 633
 634                         $info =& $this->items[$ns][$tag];
 635                         $finalName = isset( $info['map_name'] )
 636                                 ? $info['map_name'] : $tag;
 637
 638                         if ( is_array( $info['validate'] ) ) {
 639                                 $validate = $info['validate'];
 640                         } else {
 641                                 $validator = new XMPValidate( $this->logger );
 642                                 $validate = array( $validator, $info['validate'] );
 643                         }
 644
 645                         if ( !isset( $this->results['xmp-' . $info['map_group']][$finalName] ) ) {
 646                                 // This can happen if all the members of the struct failed validation.
 647                                 $this->logger->debug( __METHOD__ . " <$ns:$tag> has no valid members." );
 648                         } elseif ( is_callable( $validate ) ) {
 649                                 $val =& $this->results['xmp-' . $info['map_group']][$finalName];
 650                                 call_user_func_array( $validate, array( $info, &$val, false ) );
 651                                 if ( is_null( $val ) ) {
 652                                         // the idea being the validation function will unset the variable if
 653                                         // its invalid.
 654                                         $this->logger->info( __METHOD__ . " <$ns:$tag> failed validation." );
 655                                         unset( $this->results['xmp-' . $info['map_group']][$finalName] );
 656                                 }
 657                         } else {
 658                                 $this->logger->warning( __METHOD__ . " Validation function for $finalName ("
 659                                         . $validate[0] . '::' . $validate[1] . '()) is not callable.' );
 660                         }
 661                 }
 662
 663                 array_shift( $this->curItem );
 664                 array_shift( $this->mode );
 665                 $this->ancestorStruct = false;
 666                 $this->processingArray = false;
 667                 $this->itemLang = false;
 668         }
 669
 670         /**
 671          * Hit a closing element in MODE_LI (either rdf:Seq, or rdf:Bag )
 672          * Add information about what type of element this is.
 673          *
 674          * Note we still have to hit the outer "</property>"
 675          *
 676          * @par For example, when processing:
 677          * @code{,xml}
 678          * <exif:ISOSpeedRatings> <rdf:Seq> <rdf:li>64</rdf:li>
 679          *   </rdf:Seq> </exif:ISOSpeedRatings>
 680          * @endcode
 681          *
 682          * This method is called when we hit the "</rdf:Seq>".
 683          * (For comparison, we call endElementModeSimple when we
 684          * hit the "</rdf:li>")
 685          *
 686          * @param string $elm Namespace . ' ' . element name
 687          * @throws RuntimeException
 688          */
 689         private function endElementModeLi( $elm ) {
 690
 691                 list( $ns, $tag ) = explode( ' ', $this->curItem[0], 2 );
 692                 $info = $this->items[$ns][$tag];
 693                 $finalName = isset( $info['map_name'] )
 694                         ? $info['map_name'] : $tag;
 695
 696                 array_shift( $this->mode );
 697
 698                 if ( !isset( $this->results['xmp-' . $info['map_group']][$finalName] ) ) {
 699                         $this->logger->debug( __METHOD__ . " Empty compund element $finalName." );
 700
 701                         return;
 702                 }
 703
 704                 if ( $elm === self::NS_RDF . ' Seq' ) {
 705                         $this->results['xmp-' . $info['map_group']][$finalName]['_type'] = 'ol';
 706                 } elseif ( $elm === self::NS_RDF . ' Bag' ) {
 707                         $this->results['xmp-' . $info['map_group']][$finalName]['_type'] = 'ul';
 708                 } elseif ( $elm === self::NS_RDF . ' Alt' ) {
 709                         // extra if needed as you could theoretically have a non-language alt.
 710                         if ( $info['mode'] === self::MODE_LANG ) {
 711                                 $this->results['xmp-' . $info['map_group']][$finalName]['_type'] = 'lang';
 712                         }
 713                 } else {
 714                         throw new RuntimeException( __METHOD__ . " expected </rdf:seq> or </rdf:bag> but instead got $elm." );
 715                 }
 716         }
 717
 718         /**
 719          * End element while in MODE_QDESC
 720          * mostly when ending an element when we have a simple value
 721          * that has qualifiers.
 722          *
 723          * Qualifiers aren't all that common, and we don't do anything
 724          * with them.
 725          *
 726          * @param string $elm Namespace and element
 727          */
 728         private function endElementModeQDesc( $elm ) {
 729
 730                 if ( $elm === self::NS_RDF . ' value' ) {
 731                         list( $ns, $tag ) = explode( ' ', $this->curItem[0], 2 );
 732                         $this->saveValue( $ns, $tag, $this->charContent );
 733
 734                         return;
 735                 } else {
 736                         array_shift( $this->mode );
 737                         array_shift( $this->curItem );
 738                 }
 739         }
 740
 741         /**
 742          * Handler for hitting a closing element.
 743          *
 744          * generally just calls a helper function depending on what
 745          * mode we're in.
 746          *
 747          * Ignores the outer wrapping elements that are optional in
 748          * xmp and have no meaning.
 749          *
 750          * @param XMLParser $parser
 751          * @param string $elm Namespace . ' ' . element name
 752          * @throws RuntimeException
 753          */
 754         function endElement( $parser, $elm ) {
 755                 if ( $elm === ( self::NS_RDF . ' RDF' )
 756                         || $elm === 'adobe:ns:meta/ xmpmeta'
 757                         || $elm === 'adobe:ns:meta/ xapmeta'
 758                 ) {
 759                         // ignore these.
 760                         return;
 761                 }
 762
 763                 if ( $elm === self::NS_RDF . ' type' ) {
 764                         // these aren't really supported properly yet.
 765                         // However, it appears they almost never used.
 766                         $this->logger->info( __METHOD__ . ' encountered <rdf:type>' );
 767                 }
 768
 769                 if ( strpos( $elm, ' ' ) === false ) {
 770                         // This probably shouldn't happen.
 771                         // However, there is a bug in an adobe product
 772                         // that forgets the namespace on some things.
 773                         // (Luckily they are unimportant things).
 774                         $this->logger->info( __METHOD__ . " Encountered </$elm> which has no namespace. Skipping." );
 775
 776                         return;
 777                 }
 778
 779                 if ( count( $this->mode[0] ) === 0 ) {
 780                         // This should never ever happen and means
 781                         // there is a pretty major bug in this class.
 782                         throw new RuntimeException( 'Encountered end element with no mode' );
 783                 }
 784
 785                 if ( count( $this->curItem ) == 0 && $this->mode[0] !== self::MODE_INITIAL ) {
 786                         // just to be paranoid. Should always have a curItem, except for initially
 787                         // (aka during MODE_INITAL).
 788                         throw new RuntimeException( "Hit end element </$elm> but no curItem" );
 789                 }
 790
 791                 switch ( $this->mode[0] ) {
 792                         case self::MODE_IGNORE:
 793                                 $this->endElementModeIgnore( $elm );
 794                                 break;
 795                         case self::MODE_SIMPLE:
 796                                 $this->endElementModeSimple( $elm );
 797                                 break;
 798                         case self::MODE_STRUCT:
 799                         case self::MODE_SEQ:
 800                         case self::MODE_BAG:
 801                         case self::MODE_LANG:
 802                         case self::MODE_BAGSTRUCT:
 803                                 $this->endElementNested( $elm );
 804                                 break;
 805                         case self::MODE_INITIAL:
 806                                 if ( $elm === self::NS_RDF . ' Description' ) {
 807                                         array_shift( $this->mode );
 808                                 } else {
 809                                         throw new RuntimeException( 'Element ended unexpectedly while in MODE_INITIAL' );
 810                                 }
 811                                 break;
 812                         case self::MODE_LI:
 813                         case self::MODE_LI_LANG:
 814                                 $this->endElementModeLi( $elm );
 815                                 break;
 816                         case self::MODE_QDESC:
 817                                 $this->endElementModeQDesc( $elm );
 818                                 break;
 819                         default:
 820                                 $this->logger->warning( __METHOD__ . " no mode (elm = $elm)" );
 821                                 break;
 822                 }
 823         }
 824
 825         /**
 826          * Hit an opening element while in MODE_IGNORE
 827          *
 828          * XMP is extensible, so ignore any tag we don't understand.
 829          *
 830          * Mostly ignores, unless we encounter the element that we are ignoring.
 831          * in which case we add it to the item stack, so we can ignore things
 832          * that are nested, correctly.
 833          *
 834          * @param string $elm Namespace . ' ' . tag name
 835          */
 836         private function startElementModeIgnore( $elm ) {
 837                 if ( $elm === $this->curItem[0] ) {
 838                         array_unshift( $this->curItem, $elm );
 839                         array_unshift( $this->mode, self::MODE_IGNORE );
 840                 }
 841         }
 842
 843         /**
 844          *  Start element in MODE_BAG (unordered array)
 845          * this should always be <rdf:Bag>
 846          *
 847          * @param string $elm Namespace . ' ' . tag
 848          * @throws RuntimeException If we have an element that's not <rdf:Bag>
 849          */
 850         private function startElementModeBag( $elm ) {
 851                 if ( $elm === self::NS_RDF . ' Bag' ) {
 852                         array_unshift( $this->mode, self::MODE_LI );
 853                 } else {
 854                         throw new RuntimeException( "Expected <rdf:Bag> but got $elm." );
 855                 }
 856         }
 857
 858         /**
 859          * Start element in MODE_SEQ (ordered array)
 860          * this should always be <rdf:Seq>
 861          *
 862          * @param string $elm Namespace . ' ' . tag
 863          * @throws RuntimeException If we have an element that's not <rdf:Seq>
 864          */
 865         private function startElementModeSeq( $elm ) {
 866                 if ( $elm === self::NS_RDF . ' Seq' ) {
 867                         array_unshift( $this->mode, self::MODE_LI );
 868                 } elseif ( $elm === self::NS_RDF . ' Bag' ) {
 869                         # bug 27105
 870                         $this->logger->info( __METHOD__ . ' Expected an rdf:Seq, but got an rdf:Bag. Pretending'
 871                                 . ' it is a Seq, since some buggy software is known to screw this up.' );
 872                         array_unshift( $this->mode, self::MODE_LI );
 873                 } else {
 874                         throw new RuntimeException( "Expected <rdf:Seq> but got $elm." );
 875                 }
 876         }
 877
 878         /**
 879          * Start element in MODE_LANG (language alternative)
 880          * this should always be <rdf:Alt>
 881          *
 882          * This tag tends to be used for metadata like describe this
 883          * picture, which can be translated into multiple languages.
 884          *
 885          * XMP supports non-linguistic alternative selections,
 886          * which are really only used for thumbnails, which
 887          * we don't care about.
 888          *
 889          * @param string $elm Namespace . ' ' . tag
 890          * @throws RuntimeException If we have an element that's not <rdf:Alt>
 891          */
 892         private function startElementModeLang( $elm ) {
 893                 if ( $elm === self::NS_RDF . ' Alt' ) {
 894                         array_unshift( $this->mode, self::MODE_LI_LANG );
 895                 } else {
 896                         throw new RuntimeException( "Expected <rdf:Seq> but got $elm." );
 897                 }
 898         }
 899
 900         /**
 901          * Handle an opening element when in MODE_SIMPLE
 902          *
 903          * This should not happen often. This is for if a simple element
 904          * already opened has a child element. Could happen for a
 905          * qualified element.
 906          *
 907          * For example:
 908          * <exif:DigitalZoomRatio><rdf:Description><rdf:value>0/10</rdf:value>
 909          *   <foo:someQualifier>Bar</foo:someQualifier> </rdf:Description>
 910          *   </exif:DigitalZoomRatio>
 911          *
 912          * This method is called when processing the <rdf:Description> element
 913          *
 914          * @param string $elm Namespace and tag names separated by space.
 915          * @param array $attribs Attributes of the element.
 916          * @throws RuntimeException
 917          */
 918         private function startElementModeSimple( $elm, $attribs ) {
 919                 if ( $elm === self::NS_RDF . ' Description' ) {
 920                         // If this value has qualifiers
 921                         array_unshift( $this->mode, self::MODE_QDESC );
 922                         array_unshift( $this->curItem, $this->curItem[0] );
 923
 924                         if ( isset( $attribs[self::NS_RDF . ' value'] ) ) {
 925                                 list( $ns, $tag ) = explode( ' ', $this->curItem[0], 2 );
 926                                 $this->saveValue( $ns, $tag, $attribs[self::NS_RDF . ' value'] );
 927                         }
 928                 } elseif ( $elm === self::NS_RDF . ' value' ) {
 929                         // This should not be here.
 930                         throw new RuntimeException( __METHOD__ . ' Encountered <rdf:value> where it was unexpected.' );
 931                 } else {
 932                         // something else we don't recognize, like a qualifier maybe.
 933                         $this->logger->info( __METHOD__ .
 934                                 " Encountered element <$elm> where only expecting character data as value of " .
 935                                 $this->curItem[0] );
 936                         array_unshift( $this->mode, self::MODE_IGNORE );
 937                         array_unshift( $this->curItem, $elm );
 938                 }
 939         }
 940
 941         /**
 942          * Start an element when in MODE_QDESC.
 943          * This generally happens when a simple element has an inner
 944          * rdf:Description to hold qualifier elements.
 945          *
 946          * For example in:
 947          * <exif:DigitalZoomRatio><rdf:Description><rdf:value>0/10</rdf:value>
 948          *   <foo:someQualifier>Bar</foo:someQualifier> </rdf:Description>
 949          *   </exif:DigitalZoomRatio>
 950          * Called when processing the <rdf:value> or <foo:someQualifier>.
 951          *
 952          * @param string $elm Namespace and tag name separated by a space.
 953          *
 954          */
 955         private function startElementModeQDesc( $elm ) {
 956                 if ( $elm === self::NS_RDF . ' value' ) {
 957                         return; // do nothing
 958                 } else {
 959                         // otherwise its a qualifier, which we ignore
 960                         array_unshift( $this->mode, self::MODE_IGNORE );
 961                         array_unshift( $this->curItem, $elm );
 962                 }
 963         }
 964
 965         /**
 966          * Starting an element when in MODE_INITIAL
 967          * This usually happens when we hit an element inside
 968          * the outer rdf:Description
 969          *
 970          * This is generally where most properties start.
 971          *
 972          * @param string $ns Namespace
 973          * @param string $tag Tag name (without namespace prefix)
 974          * @param array $attribs Array of attributes
 975          * @throws RuntimeException
 976          */
 977         private function startElementModeInitial( $ns, $tag, $attribs ) {
 978                 if ( $ns !== self::NS_RDF ) {
 979
 980                         if ( isset( $this->items[$ns][$tag] ) ) {
 981                                 if ( isset( $this->items[$ns][$tag]['structPart'] ) ) {
 982                                         // If this element is supposed to appear only as
 983                                         // a child of a structure, but appears here (not as
 984                                         // a child of a struct), then something weird is
 985                                         // happening, so ignore this element and its children.
 986
 987                                         $this->logger->warning( "Encountered <$ns:$tag> outside"
 988                                                 . " of its expected parent. Ignoring." );
 989
 990                                         array_unshift( $this->mode, self::MODE_IGNORE );
 991                                         array_unshift( $this->curItem, $ns . ' ' . $tag );
 992
 993                                         return;
 994                                 }
 995                                 $mode = $this->items[$ns][$tag]['mode'];
 996                                 array_unshift( $this->mode, $mode );
 997                                 array_unshift( $this->curItem, $ns . ' ' . $tag );
 998                                 if ( $mode === self::MODE_STRUCT ) {
 999                                         $this->ancestorStruct = isset( $this->items[$ns][$tag]['map_name'] )
1000                                                 ? $this->items[$ns][$tag]['map_name'] : $tag;
1001                                 }
1002                                 if ( $this->charContent !== false ) {
1003                                         // Something weird.
1004                                         // Should not happen in valid XMP.
1005                                         throw new RuntimeException( 'tag nested in non-whitespace characters.' );
1006                                 }
1007                         } else {
1008                                 // This element is not on our list of allowed elements so ignore.
1009                                 $this->logger->debug( __METHOD__ . " Ignoring unrecognized element <$ns:$tag>." );
1010                                 array_unshift( $this->mode, self::MODE_IGNORE );
1011                                 array_unshift( $this->curItem, $ns . ' ' . $tag );
1012
1013                                 return;
1014                         }
1015                 }
1016                 // process attributes
1017                 $this->doAttribs( $attribs );
1018         }
1019
1020         /**
1021          * Hit an opening element when in a Struct (MODE_STRUCT)
1022          * This is generally for fields of a compound property.
1023          *
1024          * Example of a struct (abbreviated; flash has more properties):
1025          *
1026          * <exif:Flash> <rdf:Description> <exif:Fired>True</exif:Fired>
1027          *  <exif:Mode>1</exif:Mode></rdf:Description></exif:Flash>
1028          *
1029          * or:
1030          *
1031          * <exif:Flash rdf:parseType='Resource'> <exif:Fired>True</exif:Fired>
1032          *  <exif:Mode>1</exif:Mode></exif:Flash>
1033          *
1034          * @param string $ns Namespace
1035          * @param string $tag Tag name (no ns)
1036          * @param array $attribs Array of attribs w/ values.
1037          * @throws RuntimeException
1038          */
1039         private function startElementModeStruct( $ns, $tag, $attribs ) {
1040                 if ( $ns !== self::NS_RDF ) {
1041
1042                         if ( isset( $this->items[$ns][$tag] ) ) {
1043                                 if ( isset( $this->items[$ns][$this->ancestorStruct]['children'] )
1044                                         && !isset( $this->items[$ns][$this->ancestorStruct]['children'][$tag] )
1045                                 ) {
1046                                         // This assumes that we don't have inter-namespace nesting
1047                                         // which we don't in all the properties we're interested in.
1048                                         throw new RuntimeException( " <$tag> appeared nested in <" . $this->ancestorStruct
1049                                                 . "> where it is not allowed." );
1050                                 }
1051                                 array_unshift( $this->mode, $this->items[$ns][$tag]['mode'] );
1052                                 array_unshift( $this->curItem, $ns . ' ' . $tag );
1053                                 if ( $this->charContent !== false ) {
1054                                         // Something weird.
1055                                         // Should not happen in valid XMP.
1056                                         throw new RuntimeException( "tag <$tag> nested in non-whitespace characters (" .
1057                                                 $this->charContent . ")." );
1058                                 }
1059                         } else {
1060                                 array_unshift( $this->mode, self::MODE_IGNORE );
1061                                 array_unshift( $this->curItem, $elm );
1062
1063                                 return;
1064                         }
1065                 }
1066
1067                 if ( $ns === self::NS_RDF && $tag === 'Description' ) {
1068                         $this->doAttribs( $attribs );
1069                         array_unshift( $this->mode, self::MODE_STRUCT );
1070                         array_unshift( $this->curItem, $this->curItem[0] );
1071                 }
1072         }
1073
1074         /**
1075          * opening element in MODE_LI
1076          * process elements of arrays.
1077          *
1078          * Example:
1079          * <exif:ISOSpeedRatings> <rdf:Seq> <rdf:li>64</rdf:li>
1080          *   </rdf:Seq> </exif:ISOSpeedRatings>
1081          * This method is called when we hit the <rdf:li> element.
1082          *
1083          * @param string $elm Namespace . ' ' . tagname
1084          * @param array $attribs Attributes. (needed for BAGSTRUCTS)
1085          * @throws RuntimeException If gets a tag other than <rdf:li>
1086          */
1087         private function startElementModeLi( $elm, $attribs ) {
1088                 if ( ( $elm ) !== self::NS_RDF . ' li' ) {
1089                         throw new RuntimeException( "<rdf:li> expected but got $elm." );
1090                 }
1091
1092                 if ( !isset( $this->mode[1] ) ) {
1093                         // This should never ever ever happen. Checking for it
1094                         // to be paranoid.
1095                         throw new RuntimeException( 'In mode Li, but no 2xPrevious mode!' );
1096                 }
1097
1098                 if ( $this->mode[1] === self::MODE_BAGSTRUCT ) {
1099                         // This list item contains a compound (STRUCT) value.
1100                         array_unshift( $this->mode, self::MODE_STRUCT );
1101                         array_unshift( $this->curItem, $elm );
1102                         $this->processingArray = true;
1103
1104                         if ( !isset( $this->curItem[1] ) ) {
1105                                 // be paranoid.
1106                                 throw new RuntimeException( 'Can not find parent of BAGSTRUCT.' );
1107                         }
1108                         list( $curNS, $curTag ) = explode( ' ', $this->curItem[1] );
1109                         $this->ancestorStruct = isset( $this->items[$curNS][$curTag]['map_name'] )
1110                                 ? $this->items[$curNS][$curTag]['map_name'] : $curTag;
1111
1112                         $this->doAttribs( $attribs );
1113                 } else {
1114                         // Normal BAG or SEQ containing simple values.
1115                         array_unshift( $this->mode, self::MODE_SIMPLE );
1116                         // need to add curItem[0] on again since one is for the specific item
1117                         // and one is for the entire group.
1118                         array_unshift( $this->curItem, $this->curItem[0] );
1119                         $this->processingArray = true;
1120                 }
1121         }
1122
1123         /**
1124          * Opening element in MODE_LI_LANG.
1125          * process elements of language alternatives
1126          *
1127          * Example:
1128          * <dc:title> <rdf:Alt> <rdf:li xml:lang="x-default">My house
1129          *  </rdf:li> </rdf:Alt> </dc:title>
1130          *
1131          * This method is called when we hit the <rdf:li> element.
1132          *
1133          * @param string $elm Namespace . ' ' . tag
1134          * @param array $attribs Array of elements (most importantly xml:lang)
1135          * @throws RuntimeException If gets a tag other than <rdf:li> or if no xml:lang
1136          */
1137         private function startElementModeLiLang( $elm, $attribs ) {
1138                 if ( $elm !== self::NS_RDF . ' li' ) {
1139                         throw new RuntimeException( __METHOD__ . " <rdf:li> expected but got $elm." );
1140                 }
1141                 if ( !isset( $attribs[self::NS_XML . ' lang'] )
1142                         || !preg_match( '/^[-A-Za-z0-9]{2,}$/D', $attribs[self::NS_XML . ' lang'] )
1143                 ) {
1144                         throw new RuntimeException( __METHOD__
1145                                 . " <rdf:li> did not contain, or has invalid xml:lang attribute in lang alternative" );
1146                 }
1147
1148                 // Lang is case-insensitive.
1149                 $this->itemLang = strtolower( $attribs[self::NS_XML . ' lang'] );
1150
1151                 // need to add curItem[0] on again since one is for the specific item
1152                 // and one is for the entire group.
1153                 array_unshift( $this->curItem, $this->curItem[0] );
1154                 array_unshift( $this->mode, self::MODE_SIMPLE );
1155                 $this->processingArray = true;
1156         }
1157
1158         /**
1159          * Hits an opening element.
1160          * Generally just calls a helper based on what MODE we're in.
1161          * Also does some initial set up for the wrapper element
1162          *
1163          * @param XMLParser $parser
1164          * @param string $elm Namespace "<space>" element
1165          * @param array $attribs Attribute name => value
1166          * @throws RuntimeException
1167          */
1168         function startElement( $parser, $elm, $attribs ) {
1169
1170                 if ( $elm === self::NS_RDF . ' RDF'
1171                         || $elm === 'adobe:ns:meta/ xmpmeta'
1172                         || $elm === 'adobe:ns:meta/ xapmeta'
1173                 ) {
1174                         /* ignore. */
1175                         return;
1176                 } elseif ( $elm === self::NS_RDF . ' Description' ) {
1177                         if ( count( $this->mode ) === 0 ) {
1178                                 // outer rdf:desc
1179                                 array_unshift( $this->mode, self::MODE_INITIAL );
1180                         }
1181                 } elseif ( $elm === self::NS_RDF . ' type' ) {
1182                         // This doesn't support rdf:type properly.
1183                         // In practise I have yet to see a file that
1184                         // uses this element, however it is mentioned
1185                         // on page 25 of part 1 of the xmp standard.
1186                         //
1187                         // also it seems as if exiv2 and exiftool do not support
1188                         // this either (That or I misunderstand the standard)
1189                         $this->logger->info( __METHOD__ . ' Encountered <rdf:type> which isn\'t currently supported' );
1190                 }
1191
1192                 if ( strpos( $elm, ' ' ) === false ) {
1193                         // This probably shouldn't happen.
1194                         $this->logger->info( __METHOD__ . " Encountered <$elm> which has no namespace. Skipping." );
1195
1196                         return;
1197                 }
1198
1199                 list( $ns, $tag ) = explode( ' ', $elm, 2 );
1200
1201                 if ( count( $this->mode ) === 0 ) {
1202                         // This should not happen.
1203                         throw new RuntimeException( 'Error extracting XMP, '
1204                                 . "encountered <$elm> with no mode" );
1205                 }
1206
1207                 switch ( $this->mode[0] ) {
1208                         case self::MODE_IGNORE:
1209                                 $this->startElementModeIgnore( $elm );
1210                                 break;
1211                         case self::MODE_SIMPLE:
1212                                 $this->startElementModeSimple( $elm, $attribs );
1213                                 break;
1214                         case self::MODE_INITIAL:
1215                                 $this->startElementModeInitial( $ns, $tag, $attribs );
1216                                 break;
1217                         case self::MODE_STRUCT:
1218                                 $this->startElementModeStruct( $ns, $tag, $attribs );
1219                                 break;
1220                         case self::MODE_BAG:
1221                         case self::MODE_BAGSTRUCT:
1222                                 $this->startElementModeBag( $elm );
1223                                 break;
1224                         case self::MODE_SEQ:
1225                                 $this->startElementModeSeq( $elm );
1226                                 break;
1227                         case self::MODE_LANG:
1228                                 $this->startElementModeLang( $elm );
1229                                 break;
1230                         case self::MODE_LI_LANG:
1231                                 $this->startElementModeLiLang( $elm, $attribs );
1232                                 break;
1233                         case self::MODE_LI:
1234                                 $this->startElementModeLi( $elm, $attribs );
1235                                 break;
1236                         case self::MODE_QDESC:
1237                                 $this->startElementModeQDesc( $elm );
1238                                 break;
1239                         default:
1240                                 throw new RuntimeException( 'StartElement in unknown mode: ' . $this->mode[0] );
1241                 }
1242         }
1243
1244         /**
1245          * Process attributes.
1246          * Simple values can be stored as either a tag or attribute
1247          *
1248          * Often the initial "<rdf:Description>" tag just has all the simple
1249          * properties as attributes.
1250          *
1251          * @codingStandardsIgnoreStart Long line that cannot be broken
1252          * @par Example:
1253          * @code
1254          * <rdf:Description rdf:about="" xmlns:exif="http://ns.adobe.com/exif/1.0/" exif:DigitalZoomRatio="0/10">
1255          * @endcode
1256          * @codingStandardsIgnoreEnd
1257          *
1258          * @param array $attribs Array attribute=>value
1259          * @throws RuntimeException
1260          */
1261         private function doAttribs( $attribs ) {
1262                 // first check for rdf:parseType attribute, as that can change
1263                 // how the attributes are interperted.
1264
1265                 if ( isset( $attribs[self::NS_RDF . ' parseType'] )
1266                         && $attribs[self::NS_RDF . ' parseType'] === 'Resource'
1267                         && $this->mode[0] === self::MODE_SIMPLE
1268                 ) {
1269                         // this is equivalent to having an inner rdf:Description
1270                         $this->mode[0] = self::MODE_QDESC;
1271                 }
1272                 foreach ( $attribs as $name => $val ) {
1273                         if ( strpos( $name, ' ' ) === false ) {
1274                                 // This shouldn't happen, but so far some old software forgets namespace
1275                                 // on rdf:about.
1276                                 $this->logger->info( __METHOD__ . ' Encountered non-namespaced attribute: '
1277                                         . " $name=\"$val\". Skipping. " );
1278                                 continue;
1279                         }
1280                         list( $ns, $tag ) = explode( ' ', $name, 2 );
1281                         if ( $ns === self::NS_RDF ) {
1282                                 if ( $tag === 'value' || $tag === 'resource' ) {
1283                                         // resource is for url.
1284                                         // value attribute is a weird way of just putting the contents.
1285                                         $this->char( $this->xmlParser, $val );
1286                                 }
1287                         } elseif ( isset( $this->items[$ns][$tag] ) ) {
1288                                 if ( $this->mode[0] === self::MODE_SIMPLE ) {
1289                                         throw new RuntimeException( __METHOD__
1290                                                 . " $ns:$tag found as attribute where not allowed" );
1291                                 }
1292                                 $this->saveValue( $ns, $tag, $val );
1293                         } else {
1294                                 $this->logger->debug( __METHOD__ . " Ignoring unrecognized element <$ns:$tag>." );
1295                         }
1296                 }
1297         }
1298
1299         /**
1300          * Given an extracted value, save it to results array
1301          *
1302          * note also uses $this->ancestorStruct and
1303          * $this->processingArray to determine what name to
1304          * save the value under. (in addition to $tag).
1305          *
1306          * @param string $ns Namespace of tag this is for
1307          * @param string $tag Tag name
1308          * @param string $val Value to save
1309          */
1310         private function saveValue( $ns, $tag, $val ) {
1311
1312                 $info =& $this->items[$ns][$tag];
1313                 $finalName = isset( $info['map_name'] )
1314                         ? $info['map_name'] : $tag;
1315                 if ( isset( $info['validate'] ) ) {
1316                         if ( is_array( $info['validate'] ) ) {
1317                                 $validate = $info['validate'];
1318                         } else {
1319                                 $validator = new XMPValidate( $this->logger );
1320                                 $validate = array( $validator, $info['validate'] );
1321                         }
1322
1323                         if ( is_callable( $validate ) ) {
1324                                 call_user_func_array( $validate, array( $info, &$val, true ) );
1325                                 // the reasoning behind using &$val instead of using the return value
1326                                 // is to be consistent between here and validating structures.
1327                                 if ( is_null( $val ) ) {
1328                                         $this->logger->info( __METHOD__ . " <$ns:$tag> failed validation." );
1329
1330                                         return;
1331                                 }
1332                         } else {
1333                                 $this->logger->warning( __METHOD__ . " Validation function for $finalName ("
1334                                         . $validate[0] . '::' . $validate[1] . '()) is not callable.' );
1335                         }
1336                 }
1337
1338                 if ( $this->ancestorStruct && $this->processingArray ) {
1339                         // Aka both an array and a struct. ( self::MODE_BAGSTRUCT )
1340                         $this->results['xmp-' . $info['map_group']][$this->ancestorStruct][][$finalName] = $val;
1341                 } elseif ( $this->ancestorStruct ) {
1342                         $this->results['xmp-' . $info['map_group']][$this->ancestorStruct][$finalName] = $val;
1343                 } elseif ( $this->processingArray ) {
1344                         if ( $this->itemLang === false ) {
1345                                 // normal array
1346                                 $this->results['xmp-' . $info['map_group']][$finalName][] = $val;
1347                         } else {
1348                                 // lang array.
1349                                 $this->results['xmp-' . $info['map_group']][$finalName][$this->itemLang] = $val;
1350                         }
1351                 } else {
1352                         $this->results['xmp-' . $info['map_group']][$finalName] = $val;
1353                 }
1354         }
1355 }