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Reader.php
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<?php
/**
* Reader for XMP data containing properties relevant to images.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
* @ingroup Media
*/
namespace Wikimedia\XMPReader;
use Exception;
use Psr\Log\LoggerAwareInterface;
use Psr\Log\LoggerAwareTrait;
use Psr\Log\LoggerInterface;
use Psr\Log\NullLogger;
use RuntimeException;
use Wikimedia\ScopedCallback;
use XMLReader;
/**
* Class for reading xmp data containing properties relevant to
* images, and spitting out an array that FormatMetadata accepts.
*
* Note, this is not meant to recognize every possible thing you can
* encode in XMP. It should recognize all the properties we want.
* For example, it doesn't have support for structures with multiple
* nesting levels, as none of the properties we're supporting use that
* feature. If it comes across properties it doesn't recognize, it should
* ignore them.
*
* The public methods one would call in this class are
* - parse( $content )
* Reads in xmp content.
* Can potentially be called multiple times with partial data each time.
* - parseExtended( $content )
* Reads XMPExtended blocks (jpeg files only).
* - getResults
* Outputs a results array.
*
* Note XMP kind of looks like rdf. They are not the same thing - XMP is
* encoded as a specific subset of rdf. This class can read XMP. It cannot
* read rdf.
*/
class Reader implements LoggerAwareInterface {
use LoggerAwareTrait;
/** @var array XMP item configuration array */
protected array $items;
/** @var array Array to hold the current element (and previous element, and so on) */
private array $curItem = [];
/** @var bool|string The structure name when processing nested structures. */
private $ancestorStruct = false;
/** @var bool|string Temporary holder for character data that appears in xmp doc. */
private $charContent = false;
/** @var array Stores the state the xmpreader is in (see MODE_FOO constants) */
private array $mode = [];
/** @var array Array to hold results */
private array $results = [];
/** @var bool If we're doing a seq or bag. */
private bool $processingArray = false;
/** @var bool|string Used for lang alts only */
private $itemLang = false;
/** @var resource|null A resource handle for the XML parser */
private $xmlParser;
/** @var bool|string Character set like 'UTF-8' */
private $charset = false;
/** @var int */
private int $extendedXMPOffset = 0;
/** @var int Flag determining if the XMP is safe to parse */
private int $parsable = 0;
/** @var string Buffer of XML to parse */
private string $xmlParsableBuffer = '';
/**
* @var string
*/
private string $filename;
/**
* These are various mode constants.
* they are used to figure out what to do
* with an element when its encountered.
*
* For example, MODE_IGNORE is used when processing
* a property we're not interested in. So if a new
* element pops up when we're in that mode, we ignore it.
*/
private const MODE_INITIAL = 0;
private const MODE_IGNORE = 1;
private const MODE_LI = 2;
private const MODE_LI_LANG = 3;
private const MODE_QDESC = 4;
// The following MODE constants are also used in the
// $items array to denote what type of property the item is.
public const MODE_SIMPLE = 10;
// structure (associative array)
public const MODE_STRUCT = 11;
// ordered list
public const MODE_SEQ = 12;
// unordered list
public const MODE_BAG = 13;
public const MODE_LANG = 14;
// non-language alt. Currently not implemented, and not needed atm.
public const MODE_ALT = 15;
// A BAG of Structs.
public const MODE_BAGSTRUCT = 16;
private const NS_RDF = 'http://www.w3.org/1999/02/22-rdf-syntax-ns#';
private const NS_XML = 'http://www.w3.org/XML/1998/namespace';
// States used while determining if XML is safe to parse
private const PARSABLE_UNKNOWN = 0;
private const PARSABLE_OK = 1;
private const PARSABLE_BUFFERING = 2;
private const PARSABLE_NO = 3;
/**
* Primary job is to initialize the XMLParser
*
* @param LoggerInterface|null $logger Logger instance if available
* @param string $filename
*/
public function __construct( ?LoggerInterface $logger = null, $filename = 'unknown' ) {
if ( $logger ) {
$this->setLogger( $logger );
} else {
$this->setLogger( new NullLogger() );
}
$this->filename = $filename;
$this->items = Info::getItems();
$this->resetXMLParser();
}
/**
* free the XML parser.
*
* @note It is unclear to me if we really need to do this ourselves
* or if php garbage collection will automatically free the xmlParser
* when it is no longer needed.
*/
private function destroyXMLParser(): void {
if ( $this->xmlParser ) {
xml_parser_free( $this->xmlParser );
$this->xmlParser = null;
}
}
/**
* Main use is if a single item has multiple xmp documents describing it.
* For example in jpeg's with extendedXMP
*/
private function resetXMLParser(): void {
$this->destroyXMLParser();
$this->xmlParser = xml_parser_create_ns( 'UTF-8', ' ' );
xml_parser_set_option( $this->xmlParser, XML_OPTION_CASE_FOLDING, 0 );
xml_parser_set_option( $this->xmlParser, XML_OPTION_SKIP_WHITE, 1 );
xml_set_element_handler( $this->xmlParser,
[ $this, 'startElement' ],
[ $this, 'endElement' ] );
xml_set_character_data_handler( $this->xmlParser, [ $this, 'char' ] );
$this->parsable = self::PARSABLE_UNKNOWN;
$this->xmlParsableBuffer = '';
}
/**
* Check if this instance supports using this class
*
* @return bool
*/
public static function isSupported(): bool {
return function_exists( 'xml_parser_create_ns' ) && class_exists( XMLReader::class );
}
/**
* Get the result array. Do some post-processing before returning
* the array, and transform any metadata that is special-cased.
*
* @return array Array of results as an array of arrays suitable for
* FormatMetadata::getFormattedData().
*/
public function getResults(): array {
// xmp-special is for metadata that affects how stuff
// is extracted. For example xmpNote:HasExtendedXMP.
// It is also used to handle photoshop:AuthorsPosition
// which is weird and really part of another property,
// see 2:85 in IPTC. See also pg 21 of IPTC4XMP standard.
// The location fields also use it.
$data = $this->results;
if ( isset( $data['xmp-special']['AuthorsPosition'] )
&& is_string( $data['xmp-special']['AuthorsPosition'] )
&& isset( $data['xmp-general']['Artist'][0] )
) {
// Note, if there is more than one creator,
// this only applies to first. This also will
// only apply to the dc:Creator prop, not the
// exif:Artist prop.
$data['xmp-general']['Artist'][0] =
$data['xmp-special']['AuthorsPosition'] . ', '
. $data['xmp-general']['Artist'][0];
}
// Go through the LocationShown and LocationCreated
// changing it to the non-hierarchical form used by
// the other location fields.
if ( isset( $data['xmp-special']['LocationShown'][0] )
// @phan-suppress-next-line PhanTypeArraySuspiciousNull, PhanTypeInvalidDimOffset
&& is_array( $data['xmp-special']['LocationShown'][0] )
) {
// the is_array is just paranoia. It should always
// be an array.
foreach ( $data['xmp-special']['LocationShown'] as $loc ) {
if ( !is_array( $loc ) ) {
// To avoid copying over the _type meta-fields.
continue;
}
foreach ( $loc as $field => $val ) {
$data['xmp-general'][$field . 'Dest'][] = $val;
}
}
}
if ( isset( $data['xmp-special']['LocationCreated'][0] )
// @phan-suppress-next-line PhanTypeArraySuspiciousNull, PhanTypeInvalidDimOffset
&& is_array( $data['xmp-special']['LocationCreated'][0] )
) {
// the is_array is just paranoia. It should always
// be an array.
foreach ( $data['xmp-special']['LocationCreated'] as $loc ) {
if ( !is_array( $loc ) ) {
// To avoid copying over the _type meta-fields.
continue;
}
foreach ( $loc as $field => $val ) {
$data['xmp-general'][$field . 'Created'][] = $val;
}
}
}
// We don't want to return the special values, since they're
// special and not info to be stored about the file.
unset( $data['xmp-special'] );
// Convert GPSAltitude to negative if below sea level.
if ( isset( $data['xmp-exif']['GPSAltitudeRef'] )
&& isset( $data['xmp-exif']['GPSAltitude'] )
) {
// Must convert to a real before multiplying by -1
// Validate guarantees there will always be a '/' in this value.
[ $nom, $denom ] = explode( '/', $data['xmp-exif']['GPSAltitude'] );
// @phan-suppress-next-line PhanTypeInvalidLeftOperandOfNumericOp, PhanTypeInvalidRightOperandOfNumericOp
$data['xmp-exif']['GPSAltitude'] = $nom / $denom;
// @phan-suppress-next-line PhanTypeInvalidDimOffset
if ( $data['xmp-exif']['GPSAltitudeRef'] == '1' ) {
$data['xmp-exif']['GPSAltitude'] *= -1;
}
unset( $data['xmp-exif']['GPSAltitudeRef'] );
}
return $data;
}
/**
* Main function to parse XMP. Use getResults to get results.
*
* Also catches any errors during processing, writes them to
* debug log, blanks result array and returns false.
*
* @param string $content XMP data
* @param bool $allOfIt If this is all the data (true), or if it's split up (false). Default true
* @throws RuntimeException
* @return bool Success.
*/
public function parse( $content, $allOfIt = true ): bool {
if ( !$this->xmlParser ) {
$this->resetXMLParser();
}
try {
// detect encoding by looking for BOM which is supposed to be in processing instruction.
// see page 12 of http://www.adobe.com/devnet/xmp/pdfs/XMPSpecificationPart3.pdf
if ( !$this->charset ) {
$bom = [];
if ( preg_match( '/\xEF\xBB\xBF|\xFE\xFF|\x00\x00\xFE\xFF|\xFF\xFE\x00\x00|\xFF\xFE/',
$content, $bom )
) {
switch ( $bom[0] ) {
case "\xFE\xFF":
$this->charset = 'UTF-16BE';
break;
case "\xFF\xFE":
$this->charset = 'UTF-16LE';
break;
case "\x00\x00\xFE\xFF":
$this->charset = 'UTF-32BE';
break;
case "\xFF\xFE\x00\x00":
$this->charset = 'UTF-32LE';
break;
case "\xEF\xBB\xBF":
$this->charset = 'UTF-8';
break;
default:
// this should be impossible to get to
throw new RuntimeException( "Invalid BOM" );
}
} else {
// standard specifically says, if no bom assume utf-8
$this->charset = 'UTF-8';
}
}
if ( $this->charset !== 'UTF-8' ) {
// don't convert if already utf-8
// phpcs:ignore Generic.PHP.NoSilencedErrors.Discouraged
$content = @iconv( $this->charset, 'UTF-8//IGNORE', $content );
}
// Replace any null bytes with the replacement character (T320282)
$content = str_replace( "\0", "\u{FFFD}", $content );
// Ensure the XMP block does not have an xml doctype declaration, which
// could declare entities unsafe to parse with xml_parse (T85848/T71210).
if ( $this->parsable !== self::PARSABLE_OK ) {
if ( $this->parsable === self::PARSABLE_NO ) {
throw new RuntimeException( 'Unsafe doctype declaration in XML.' );
}
$content = $this->xmlParsableBuffer . $content;
if ( !$this->checkParseSafety( $content ) ) {
if ( !$allOfIt && $this->parsable !== self::PARSABLE_NO ) {
// parse wasn't Unsuccessful yet, so return true
// in this case.
return true;
}
$msg = ( $this->parsable === self::PARSABLE_NO ) ?
'Unsafe doctype declaration in XML.' :
'No root element found in XML.';
throw new RuntimeException( $msg );
}
}
$ok = xml_parse( $this->xmlParser, $content, $allOfIt );
if ( !$ok ) {
$code = xml_get_error_code( $this->xmlParser );
$error = xml_error_string( $code );
$line = xml_get_current_line_number( $this->xmlParser );
$col = xml_get_current_column_number( $this->xmlParser );
$offset = xml_get_current_byte_index( $this->xmlParser );
$this->logger->info(
'{method} : Error reading XMP content: {error} ' .
'(file: {file}, line: {line} column: {column} ' .
'byte offset: {offset})',
[
'method' => __METHOD__,
'error_code' => $code,
'error' => $error,
'file' => $this->filename,
'line' => $line,
'column' => $col,
'offset' => $offset,
'content' => $content,
]
);
// blank if error.
$this->results = [];
$this->destroyXMLParser();
return false;
}
} catch ( Exception $e ) {
$this->logger->warning(
'{method} {message}',
[
'method' => __METHOD__,
'message' => $e->getMessage(),
'exception' => $e,
'file' => $this->filename,
'content' => $content,
]
);
$this->results = [];
return false;
}
if ( $allOfIt ) {
$this->destroyXMLParser();
}
return true;
}
/** Entry point for XMPExtended blocks in jpeg files
*
* @todo In serious need of testing
* @see http://www.adobe.ge/devnet/xmp/pdfs/XMPSpecificationPart3.pdf XMP spec part 3 page 20
* @param string $content XMPExtended block minus the namespace signature
* @return bool If it succeeded.
*/
public function parseExtended( $content ): bool {
// @todo FIXME: This is untested. Hard to find example files
// or programs that make such files..
$guid = substr( $content, 0, 32 );
if ( !isset( $this->results['xmp-special']['HasExtendedXMP'] )
|| $this->results['xmp-special']['HasExtendedXMP'] !== $guid
) {
$this->logger->info( __METHOD__ .
" Ignoring XMPExtended block due to wrong guid (guid= '{guid}')",
[
'guid' => $guid,
'file' => $this->filename,
] );
return false;
}
$len = unpack( 'Nlength/Noffset', substr( $content, 32, 8 ) );
if ( !$len ||
$len['length'] < 4 ||
$len['offset'] < 0 ||
$len['offset'] > $len['length']
) {
$this->logger->info(
__METHOD__ . 'Error reading extended XMP block, invalid length or offset.',
[ 'file' => $this->filename ]
);
return false;
}
// we're not very robust here. we should accept it in the wrong order.
// To quote the XMP standard:
// "A JPEG writer should write the ExtendedXMP marker segments in order,
// immediately following the StandardXMP. However, the JPEG standard
// does not require preservation of marker segment order. A robust JPEG
// reader should tolerate the marker segments in any order."
// On the other hand, the probability that an image will have more than
// 128k of metadata is rather low... so the probability that it will have
// > 128k, and be in the wrong order is very low...
if ( $len['offset'] !== $this->extendedXMPOffset ) {
$this->logger->info( __METHOD__ . 'Ignoring XMPExtended block due to wrong order. (Offset was '
. $len['offset'] . ' but expected ' . $this->extendedXMPOffset . ')',
[ 'file' => $this->filename ]
);
return false;
}
if ( $len['offset'] === 0 ) {
// if we're starting the extended block, we've probably already
// done the XMPStandard block, so reset.
$this->resetXMLParser();
}
$this->extendedXMPOffset += $len['length'];
$actualContent = substr( $content, 40 );
$atEnd = ( $this->extendedXMPOffset === strlen( $actualContent ) );
$this->logger->debug(
__METHOD__ . 'Parsing a XMPExtended block',
[ 'file' => $this->filename ]
);
return $this->parse( $actualContent, $atEnd );
}
/**
* Character data handler
* Called whenever character data is found in the xmp document.
*
* does nothing if we're in MODE_IGNORE or if the data is whitespace
* throws an error if we're not in MODE_SIMPLE (as we're not allowed to have character
* data in the other modes).
*
* As an example, this happens when we encounter XMP like:
* <exif:DigitalZoomRatio>0/10</exif:DigitalZoomRatio>
* and are processing the 0/10 bit.
*
* @param resource $parser XMLParser reference to the xml parser
* @param string $data Character data
* @throws RuntimeException On invalid data
*/
public function char( $parser, $data ): void {
$data = trim( $data );
if ( trim( $data ) === "" ) {
return;
}
if ( !isset( $this->mode[0] ) ) {
throw new RuntimeException( 'Unexpected character data before first rdf:Description element' );
}
if ( $this->mode[0] === self::MODE_IGNORE ) {
return;
}
if ( $this->mode[0] !== self::MODE_SIMPLE
&& $this->mode[0] !== self::MODE_QDESC
) {
throw new RuntimeException( 'character data where not expected. (mode ' . $this->mode[0] . ')' );
}
// to check, how does this handle w.s.
if ( $this->charContent === false ) {
$this->charContent = $data;
} else {
$this->charContent .= $data;
}
}
/**
* Check if a block of XML is safe to pass to xml_parse, i.e. doesn't
* contain a doctype declaration which could contain a dos attack if we
* parse it and expand internal entities (T85848).
*
* @param string $content xml string to check for parse safety
* @return bool true if the xml is safe to parse, false otherwise
*/
private function checkParseSafety( $content ): bool {
$reader = new XMLReader();
$result = null;
// Pull in the arbitrary MAX_URI_LENGTH from libxml2...
$maxUriLength = 1024 * 1024;
$dataUri = 'data://text/plain,' . urlencode( $content );
if ( strlen( $dataUri ) > $maxUriLength ) {
// libxml2 won't parse this file as a data URI due to the length.
return false;
}
// For XMLReader to parse incomplete/invalid XML, it has to be open()'ed
// instead of using XML().
if ( !$reader->open(
$dataUri,
null,
LIBXML_NOERROR | LIBXML_NOWARNING | LIBXML_NONET
) ) {
return false;
}
if ( LIBXML_VERSION < 20900 ) {
$oldDisable = libxml_disable_entity_loader( true );
/** @noinspection PhpUnusedLocalVariableInspection */
$reset = new ScopedCallback(
'libxml_disable_entity_loader',
[ $oldDisable ]
);
}
$reader->setParserProperty( XMLReader::SUBST_ENTITIES, false );
// Even with LIBXML_NOWARNING set, XMLReader::read gives a warning
// when parsing truncated XML, which causes unit tests to fail.
// phpcs:ignore Generic.PHP.NoSilencedErrors.Discouraged
while ( @$reader->read() ) {
if ( $reader->nodeType === XMLReader::ELEMENT ) {
// Reached the first element without hitting a doctype declaration
$this->parsable = self::PARSABLE_OK;
$result = true;
break;
}
if ( $reader->nodeType === XMLReader::DOC_TYPE ) {
$this->parsable = self::PARSABLE_NO;
$result = false;
break;
}
}
if ( $result !== null ) {
return $result;
}
// Reached the end of the parsable xml without finding an element
// or doctype. Buffer and try again.
$this->parsable = self::PARSABLE_BUFFERING;
$this->xmlParsableBuffer = $content;
return false;
}
/** When we hit a closing element in MODE_IGNORE
* Check to see if this is the element we started to ignore,
* in which case we get out of MODE_IGNORE
*
* @param string $elm Namespace of element followed by a space and then tag name of element.
*/
private function endElementModeIgnore( $elm ): void {
if ( $this->curItem[0] === $elm ) {
array_shift( $this->curItem );
array_shift( $this->mode );
}
}
/**
* Hit a closing element when in MODE_SIMPLE.
* This generally means that we finished processing a
* property value, and now have to save the result to the
* results array
*
* For example, when processing:
* <exif:DigitalZoomRatio>0/10</exif:DigitalZoomRatio>
* this deals with when we hit </exif:DigitalZoomRatio>.
*
* Or it could be if we hit the end element of a property
* of a compound data structure (like a member of an array).
*
* @param string $elm Namespace, space, and tag name.
*/
private function endElementModeSimple( $elm ): void {
if ( $this->charContent !== false ) {
if ( $this->processingArray ) {
// if we're processing an array, use the original element
// name instead of rdf:li.
[ $ns, $tag ] = explode( ' ', $this->curItem[0], 2 );
} else {
[ $ns, $tag ] = explode( ' ', $elm, 2 );
}
$this->saveValue( $ns, $tag, $this->charContent );
// reset
$this->charContent = false;
}
array_shift( $this->curItem );
array_shift( $this->mode );
}
/**
* Hit a closing element in MODE_STRUCT, MODE_SEQ, MODE_BAG
* generally means we've finished processing a nested structure.
* resets some internal variables to indicate that.
*
* Note this means we hit the closing element not the "</rdf:Seq>".
*
* @par For example, when processing:
* @code{.xml}
* <exif:ISOSpeedRatings> <rdf:Seq> <rdf:li>64</rdf:li>
* </rdf:Seq> </exif:ISOSpeedRatings>
* @endcode
*
* This method is called when we hit the "</exif:ISOSpeedRatings>" tag.
*
* @param string $elm Namespace . space . tag name.
* @throws RuntimeException
*/
private function endElementNested( $elm ): void {
/* cur item must be the same as $elm, unless if in MODE_STRUCT
* in which case it could also be rdf:Description */
if ( $this->curItem[0] !== $elm
&& !( $elm === self::NS_RDF . ' Description'
&& $this->mode[0] === self::MODE_STRUCT )
) {
throw new RuntimeException( "nesting mismatch. got a </$elm> but expected a </" .
$this->curItem[0] . '>' );
}
// Validate structures.
[ $ns, $tag ] = explode( ' ', $elm, 2 );
if ( isset( $this->items[$ns][$tag]['validate'] ) ) {
$info =& $this->items[$ns][$tag];
$finalName = $info['map_name'] ?? $tag;
if ( is_array( $info['validate'] ) ) {
$validate = $info['validate'];
} else {
$validator = new Validate( $this->logger );
$validate = [ $validator, $info['validate'] ];
}
if ( !isset( $this->results['xmp-' . $info['map_group']][$finalName] ) ) {
// This can happen if all the members of the struct failed validation.
$this->logger->debug(
__METHOD__ . " <$ns:$tag> has no valid members.",
[ 'file' => $this->filename ]
);
} elseif ( is_callable( $validate ) ) {
$val =& $this->results['xmp-' . $info['map_group']][$finalName];
call_user_func_array( $validate, [ $info, &$val, false ] );
if ( $val === null ) {
// the idea being the validation function will unset the variable if
// its invalid.
$this->logger->info(
__METHOD__ . " <$ns:$tag> failed validation.",
[ 'file' => $this->filename ]
);
unset( $this->results['xmp-' . $info['map_group']][$finalName] );
}
} else {
$this->logger->warning(
__METHOD__ . " Validation function for $finalName (" .
get_class( $validate[0] ) . '::' . $validate[1] . '()) is not callable.',
[ 'file' => $this->filename ]
);
}
}
array_shift( $this->curItem );
array_shift( $this->mode );
$this->ancestorStruct = false;
$this->processingArray = false;
$this->itemLang = false;
}
/**
* Hit a closing element in MODE_LI (either rdf:Seq, or rdf:Bag )
* Add information about what type of element this is.
*
* Note we still have to hit the outer "</property>"
*
* @par For example, when processing:
* @code{.xml}
* <exif:ISOSpeedRatings> <rdf:Seq> <rdf:li>64</rdf:li>
* </rdf:Seq> </exif:ISOSpeedRatings>
* @endcode
*
* This method is called when we hit the "</rdf:Seq>".
* (For comparison, we call endElementModeSimple when we
* hit the "</rdf:li>")
*
* @param string $elm Namespace . ' ' . element name
* @throws RuntimeException
*/
private function endElementModeLi( $elm ): void {
[ $ns, $tag ] = explode( ' ', $this->curItem[0], 2 );
$info = $this->items[$ns][$tag];
$finalName = $info['map_name'] ?? $tag;
array_shift( $this->mode );
if ( !isset( $this->results['xmp-' . $info['map_group']][$finalName] ) ) {
$this->logger->debug(
__METHOD__ . " Empty compound element $finalName.",
[ 'file' => $this->filename ]
);
return;
}
if ( $elm === self::NS_RDF . ' Seq' ) {
$this->results['xmp-' . $info['map_group']][$finalName]['_type'] = 'ol';
} elseif ( $elm === self::NS_RDF . ' Bag' ) {
$this->results['xmp-' . $info['map_group']][$finalName]['_type'] = 'ul';
} elseif ( $elm === self::NS_RDF . ' Alt' ) {
// extra if needed as you could theoretically have a non-language alt.
if ( $info['mode'] === self::MODE_LANG ) {
$this->results['xmp-' . $info['map_group']][$finalName]['_type'] = 'lang';
}
} else {
throw new RuntimeException(
__METHOD__ . " expected </rdf:seq> or </rdf:bag> but instead got $elm."
);
}
}
/**
* End element while in MODE_QDESC
* mostly when ending an element when we have a simple value
* that has qualifiers.
*
* Qualifiers aren't all that common, and we don't do anything
* with them.
*
* @param string $elm Namespace and element
*/
private function endElementModeQDesc( $elm ): void {
if ( $elm === self::NS_RDF . ' value' ) {
[ $ns, $tag ] = explode( ' ', $this->curItem[0], 2 );
$this->saveValue( $ns, $tag, $this->charContent );
return;
}
array_shift( $this->mode );
array_shift( $this->curItem );
}
/**
* Handler for hitting a closing element.
*
* generally just calls a helper function depending on what
* mode we're in.
*
* Ignores the outer wrapping elements that are optional in
* xmp and have no meaning.
*
* @param resource $parser
* @param string $elm Namespace . ' ' . element name
* @throws RuntimeException
*/
public function endElement( $parser, $elm ): void {
if ( $elm === ( self::NS_RDF . ' RDF' )
|| $elm === 'adobe:ns:meta/ xmpmeta'
|| $elm === 'adobe:ns:meta/ xapmeta'
) {
// ignore these.
return;
}
if ( $elm === self::NS_RDF . ' type' ) {
// these aren't really supported properly yet.
// However, it appears they almost never used.
$this->logger->info(
__METHOD__ . ' encountered <rdf:type>',
[ 'file' => $this->filename ]
);
}
if ( strpos( $elm, ' ' ) === false ) {
// This probably shouldn't happen.
// However, there is a bug in an adobe product
// that forgets the namespace on some things.
// (Luckily they are unimportant things).
$this->logger->info(
__METHOD__ . " Encountered </$elm> which has no namespace. Skipping.",
[ 'file' => $this->filename ]
);
return;
}
if ( count( $this->mode ) === 0 ) {
// This should never ever happen and means
// there is a pretty major bug in this class.
throw new RuntimeException( 'Encountered end element with no mode' );
}
if ( count( $this->curItem ) === 0 && $this->mode[0] !== self::MODE_INITIAL ) {
// just to be paranoid. Should always have a curItem, except for initially
// (aka during MODE_INITIAL).
throw new RuntimeException( "Hit end element </$elm> but no curItem" );
}
switch ( $this->mode[0] ) {
case self::MODE_IGNORE:
$this->endElementModeIgnore( $elm );
break;
case self::MODE_SIMPLE:
$this->endElementModeSimple( $elm );
break;
case self::MODE_STRUCT:
case self::MODE_SEQ:
case self::MODE_BAG:
case self::MODE_LANG:
case self::MODE_BAGSTRUCT:
$this->endElementNested( $elm );
break;
case self::MODE_INITIAL:
if ( $elm === self::NS_RDF . ' Description' ) {
array_shift( $this->mode );
} else {
throw new RuntimeException( 'Element ended unexpectedly while in MODE_INITIAL' );
}
break;
case self::MODE_LI:
case self::MODE_LI_LANG:
$this->endElementModeLi( $elm );
break;
case self::MODE_QDESC:
$this->endElementModeQDesc( $elm );
break;
default:
$this->logger->info(
__METHOD__ . " no mode (elm = $elm)",
[ 'file' => $this->filename ]
);
break;
}
}
/**
* Hit an opening element while in MODE_IGNORE
*
* XMP is extensible, so ignore any tag we don't understand.
*
* Mostly ignores, unless we encounter the element that we are ignoring.
* in which case we add it to the item stack, so we can ignore things
* that are nested, correctly.
*
* @param string $elm Namespace . ' ' . tag name
*/
private function startElementModeIgnore( $elm ): void {
if ( $elm === $this->curItem[0] ) {
array_unshift( $this->curItem, $elm );
array_unshift( $this->mode, self::MODE_IGNORE );
}
}
/**
* Start element in MODE_BAG (unordered array)
* this should always be <rdf:Bag>
*
* @param string $elm Namespace . ' ' . tag
* @throws RuntimeException If we have an element that's not <rdf:Bag>
*/
private function startElementModeBag( $elm ): void {
if ( $elm === self::NS_RDF . ' Bag' ) {
array_unshift( $this->mode, self::MODE_LI );
} else {
throw new RuntimeException( "Expected <rdf:Bag> but got $elm." );
}
}
/**
* Start element in MODE_SEQ (ordered array)
* this should always be <rdf:Seq>
*
* @param string $elm Namespace . ' ' . tag
* @throws RuntimeException If we have an element that's not <rdf:Seq>
*/
private function startElementModeSeq( $elm ): void {
if ( $elm === self::NS_RDF . ' Seq' ) {
array_unshift( $this->mode, self::MODE_LI );
} elseif ( $elm === self::NS_RDF . ' Bag' ) {
# T29105
$this->logger->info(
__METHOD__ . ' Expected an rdf:Seq, but got an rdf:Bag. Pretending' .
' it is a Seq, since some buggy software is known to screw this up.',
[ 'file' => $this->filename ]
);
array_unshift( $this->mode, self::MODE_LI );
} else {
throw new RuntimeException( "Expected <rdf:Seq> but got $elm." );
}
}
/**
* Start element in MODE_LANG (language alternative)
* this should always be <rdf:Alt>
*
* This tag tends to be used for metadata like describe this
* picture, which can be translated into multiple languages.
*
* XMP supports non-linguistic alternative selections,
* which are really only used for thumbnails, which
* we don't care about.
*
* @param string $elm Namespace . ' ' . tag
* @throws RuntimeException If we have an element that's not <rdf:Alt>
*/
private function startElementModeLang( $elm ): void {
if ( $elm === self::NS_RDF . ' Alt' ) {
array_unshift( $this->mode, self::MODE_LI_LANG );
} else {
throw new RuntimeException( "Expected <rdf:Seq> but got $elm." );
}
}
/**
* Handle an opening element when in MODE_SIMPLE
*
* This should not happen often. This is for if a simple element
* already opened has a child element. Could happen for a
* qualified element.
*
* For example:
* <exif:DigitalZoomRatio><rdf:Description><rdf:value>0/10</rdf:value>
* <foo:someQualifier>Bar</foo:someQualifier> </rdf:Description>
* </exif:DigitalZoomRatio>
*
* This method is called when processing the <rdf:Description> element
*
* @param string $elm Namespace and tag names separated by space.
* @param array $attribs Attributes of the element.
* @throws RuntimeException
*/
private function startElementModeSimple( $elm, $attribs ): void {
if ( $elm === self::NS_RDF . ' Description' ) {
// If this value has qualifiers
array_unshift( $this->mode, self::MODE_QDESC );
array_unshift( $this->curItem, $this->curItem[0] );
if ( isset( $attribs[self::NS_RDF . ' value'] ) ) {
[ $ns, $tag ] = explode( ' ', $this->curItem[0], 2 );
$this->saveValue( $ns, $tag, $attribs[self::NS_RDF . ' value'] );
}
} elseif ( $elm === self::NS_RDF . ' value' ) {
// This should not be here.
throw new RuntimeException( __METHOD__ . ' Encountered <rdf:value> where it was unexpected.' );
} else {
// something else we don't recognize, like a qualifier maybe.
$this->logger->info( __METHOD__ .
" Encountered element <{element}> where only expecting character data as value of {curitem}",
[
'element' => $elm,
'curitem' => $this->curItem[0],
'file' => $this->filename,
]
);
array_unshift( $this->mode, self::MODE_IGNORE );
array_unshift( $this->curItem, $elm );
}
}
/**
* Start an element when in MODE_QDESC.
* This generally happens when a simple element has an inner
* rdf:Description to hold qualifier elements.
*
* For example in:
* <exif:DigitalZoomRatio><rdf:Description><rdf:value>0/10</rdf:value>
* <foo:someQualifier>Bar</foo:someQualifier> </rdf:Description>
* </exif:DigitalZoomRatio>
* Called when processing the <rdf:value> or <foo:someQualifier>.
*
* @param string $elm Namespace and tag name separated by a space.
*/
private function startElementModeQDesc( $elm ): void {
if ( $elm === self::NS_RDF . ' value' ) {
// do nothing
return;
}
// otherwise its a qualifier, which we ignore
array_unshift( $this->mode, self::MODE_IGNORE );
array_unshift( $this->curItem, $elm );
}
/**
* Starting an element when in MODE_INITIAL
* This usually happens when we hit an element inside
* the outer rdf:Description
*
* This is generally where most properties start.
*
* @param string $ns Namespace
* @param string $tag Tag name (without namespace prefix)
* @param array $attribs Array of attributes
* @throws RuntimeException
*/
private function startElementModeInitial( $ns, $tag, $attribs ): void {
if ( $ns !== self::NS_RDF ) {
if ( isset( $this->items[$ns][$tag] ) ) {
if ( isset( $this->items[$ns][$tag]['structPart'] ) ) {
// If this element is supposed to appear only as
// a child of a structure, but appears here (not as
// a child of a struct), then something weird is
// happening, so ignore this element and its children.
$this->logger->info(
'Encountered <{element}> outside of its expected parent. Ignoring.',
[ 'element' => "$ns:$tag", 'file' => $this->filename ]
);
array_unshift( $this->mode, self::MODE_IGNORE );
array_unshift( $this->curItem, $ns . ' ' . $tag );
return;
}
$mode = $this->items[$ns][$tag]['mode'];
array_unshift( $this->mode, $mode );
array_unshift( $this->curItem, $ns . ' ' . $tag );
if ( $mode === self::MODE_STRUCT ) {
$this->ancestorStruct = $this->items[$ns][$tag]['map_name'] ?? $tag;
}
if ( $this->charContent !== false ) {
// Something weird.
// Should not happen in valid XMP.
throw new RuntimeException( 'tag nested in non-whitespace characters.' );
}
} else {
// This element is not on our list of allowed elements so ignore.
$this->logger->debug( __METHOD__ . ' Ignoring unrecognized element <{element}>.',
[ 'element' => "$ns:$tag", 'file' => $this->filename ] );
array_unshift( $this->mode, self::MODE_IGNORE );
array_unshift( $this->curItem, $ns . ' ' . $tag );
return;
}
}
// process attributes
$this->doAttribs( $attribs );
}
/**
* Hit an opening element when in a Struct (MODE_STRUCT)
* This is generally for fields of a compound property.
*
* Example of a struct (abbreviated; flash has more properties):
*
* <exif:Flash> <rdf:Description> <exif:Fired>True</exif:Fired>
* <exif:Mode>1</exif:Mode></rdf:Description></exif:Flash>
*
* or:
*
* <exif:Flash rdf:parseType='Resource'> <exif:Fired>True</exif:Fired>
* <exif:Mode>1</exif:Mode></exif:Flash>
*
* @param string $ns Namespace
* @param string $tag Tag name (no ns)
* @param array $attribs Array of attribs w/ values.
* @throws RuntimeException
*/
private function startElementModeStruct( $ns, $tag, $attribs ): void {
if ( $ns !== self::NS_RDF ) {
if ( isset( $this->items[$ns][$tag] ) ) {
if ( isset( $this->items[$ns][$this->ancestorStruct]['children'] )
&& !isset( $this->items[$ns][$this->ancestorStruct]['children'][$tag] )
) {
// This assumes that we don't have inter-namespace nesting
// which we don't in all the properties we're interested in.
throw new RuntimeException( " <$tag> appeared nested in <" . $this->ancestorStruct
. "> where it is not allowed." );
}
array_unshift( $this->mode, $this->items[$ns][$tag]['mode'] );
array_unshift( $this->curItem, $ns . ' ' . $tag );
if ( $this->charContent !== false ) {
// Something weird.
// Should not happen in valid XMP.
throw new RuntimeException( "tag <$tag> nested in non-whitespace characters (" .
$this->charContent . ")." );
}
} else {
array_unshift( $this->mode, self::MODE_IGNORE );
array_unshift( $this->curItem, $ns . ' ' . $tag );
return;
}
}
if ( $ns === self::NS_RDF && $tag === 'Description' ) {
$this->doAttribs( $attribs );
array_unshift( $this->mode, self::MODE_STRUCT );
array_unshift( $this->curItem, $this->curItem[0] );
}
}
/**
* opening element in MODE_LI
* process elements of arrays.
*
* Example:
* <exif:ISOSpeedRatings> <rdf:Seq> <rdf:li>64</rdf:li>
* </rdf:Seq> </exif:ISOSpeedRatings>
* This method is called when we hit the <rdf:li> element.
*
* @param string $elm Namespace . ' ' . tagname
* @param array $attribs Attributes. (needed for BAGSTRUCTS)
* @throws RuntimeException If it gets a tag other than <rdf:li>
*/
private function startElementModeLi( $elm, $attribs ): void {
if ( ( $elm ) !== self::NS_RDF . ' li' ) {
throw new RuntimeException( "<rdf:li> expected but got $elm." );
}
if ( !isset( $this->mode[1] ) ) {
// This should never ever ever happen. Checking for it
// to be paranoid.
throw new RuntimeException( 'In mode Li, but no 2xPrevious mode!' );
}
if ( $this->mode[1] === self::MODE_BAGSTRUCT ) {
// This list item contains a compound (STRUCT) value.
array_unshift( $this->mode, self::MODE_STRUCT );
array_unshift( $this->curItem, $elm );
$this->processingArray = true;
if ( !isset( $this->curItem[1] ) ) {
// be paranoid.
throw new RuntimeException( 'Can not find parent of BAGSTRUCT.' );
}
[ $curNS, $curTag ] = explode( ' ', $this->curItem[1] );
$this->ancestorStruct = $this->items[$curNS][$curTag]['map_name'] ?? $curTag;
$this->doAttribs( $attribs );
} else {
// Normal BAG or SEQ containing simple values.
array_unshift( $this->mode, self::MODE_SIMPLE );
// need to add curItem[0] on again since one is for the specific item
// and one is for the entire group.
array_unshift( $this->curItem, $this->curItem[0] );
$this->processingArray = true;
}
}
/**
* Opening element in MODE_LI_LANG.
* process elements of language alternatives
*
* Example:
* <dc:title> <rdf:Alt> <rdf:li xml:lang="x-default">My house
* </rdf:li> </rdf:Alt> </dc:title>
*
* This method is called when we hit the <rdf:li> element.
*
* @param string $elm Namespace . ' ' . tag
* @param array $attribs Array of elements (most importantly xml:lang)
* @throws RuntimeException If it gets a tag other than <rdf:li> or if no xml:lang
*/
private function startElementModeLiLang( $elm, $attribs ): void {
if ( $elm !== self::NS_RDF . ' li' ) {
throw new RuntimeException( __METHOD__ . " <rdf:li> expected but got $elm." );
}
if ( !isset( $attribs[self::NS_XML . ' lang'] )
|| !preg_match( '/^[-A-Za-z0-9]{2,}$/D', $attribs[self::NS_XML . ' lang'] )
) {
throw new RuntimeException( __METHOD__
. " <rdf:li> did not contain, or has invalid xml:lang attribute in lang alternative" );
}
// Lang is case-insensitive.
$this->itemLang = strtolower( $attribs[self::NS_XML . ' lang'] );
// need to add curItem[0] on again since one is for the specific item
// and one is for the entire group.
array_unshift( $this->curItem, $this->curItem[0] );
array_unshift( $this->mode, self::MODE_SIMPLE );
$this->processingArray = true;
}
/**
* Hits an opening element.
* Generally just calls a helper based on what MODE we're in.
* Also does some initial set up for the wrapper element
*
* @param resource $parser
* @param string $elm Namespace "<space>" element
* @param array $attribs Attribute name => value
* @throws RuntimeException
*/
public function startElement( $parser, $elm, $attribs ): void {
if ( $elm === self::NS_RDF . ' RDF'
|| $elm === 'adobe:ns:meta/ xmpmeta'
|| $elm === 'adobe:ns:meta/ xapmeta'
) {
/* ignore. */
return;
}
if ( $elm === self::NS_RDF . ' Description' ) {
if ( count( $this->mode ) === 0 ) {
// outer rdf:desc
array_unshift( $this->mode, self::MODE_INITIAL );
}
} elseif ( $elm === self::NS_RDF . ' type' ) {
// This doesn't support rdf:type properly.
// In practise, I have yet to see a file that
// uses this element, however it is mentioned
// on page 25 of part 1 of the xmp standard.
// Also, it seems as if exiv2 and exiftool do not support
// this either (That or I misunderstand the standard)
$this->logger->info(
__METHOD__ . ' Encountered <rdf:type> which isn\'t currently supported',
[ 'file' => $this->filename ]
);
}
if ( strpos( $elm, ' ' ) === false ) {
// This probably shouldn't happen.
$this->logger->info(
__METHOD__ . " Encountered <$elm> which has no namespace. Skipping.",
[ 'file' => $this->filename ]
);
return;
}
[ $ns, $tag ] = explode( ' ', $elm, 2 );
if ( count( $this->mode ) === 0 ) {
// This should not happen.
throw new RuntimeException( 'Error extracting XMP, '
. "encountered <$elm> with no mode" );
}
switch ( $this->mode[0] ) {
case self::MODE_IGNORE:
$this->startElementModeIgnore( $elm );
break;
case self::MODE_SIMPLE:
$this->startElementModeSimple( $elm, $attribs );
break;
case self::MODE_INITIAL:
$this->startElementModeInitial( $ns, $tag, $attribs );
break;
case self::MODE_STRUCT:
$this->startElementModeStruct( $ns, $tag, $attribs );
break;
case self::MODE_BAG:
case self::MODE_BAGSTRUCT:
$this->startElementModeBag( $elm );
break;
case self::MODE_SEQ:
$this->startElementModeSeq( $elm );
break;
case self::MODE_LANG:
$this->startElementModeLang( $elm );
break;
case self::MODE_LI_LANG:
$this->startElementModeLiLang( $elm, $attribs );
break;
case self::MODE_LI:
$this->startElementModeLi( $elm, $attribs );
break;
case self::MODE_QDESC:
$this->startElementModeQDesc( $elm );
break;
default:
throw new RuntimeException( 'StartElement in unknown mode: ' . $this->mode[0] );
}
}
/**
* Process attributes.
* Simple values can be stored as either a tag or attribute
*
* Often the initial "<rdf:Description>" tag just has all the simple
* properties as attributes.
*
* @par Example:
* @code
* <rdf:Description rdf:about=""
* xmlns:exif="http://ns.adobe.com/exif/1.0/" exif:DigitalZoomRatio="0/10">
* @endcode
*
* @param array $attribs Array attribute=>value
* @throws RuntimeException
*/
private function doAttribs( $attribs ): void {
// first check for rdf:parseType attribute, as that can change
// how the attributes are interpreted.
if ( isset( $attribs[self::NS_RDF . ' parseType'] )
&& $attribs[self::NS_RDF . ' parseType'] === 'Resource'
&& $this->mode[0] === self::MODE_SIMPLE
) {
// this is equivalent to having an inner rdf:Description
$this->mode[0] = self::MODE_QDESC;
}
foreach ( $attribs as $name => $val ) {
if ( strpos( $name, ' ' ) === false ) {
// This shouldn't happen, but so far some old software forgets namespace
// on rdf:about.
$this->logger->info(
__METHOD__ . ' Encountered non-namespaced attribute: ' .
" $name=\"$val\". Skipping. ",
[ 'file' => $this->filename ]
);
continue;
}
[ $ns, $tag ] = explode( ' ', $name, 2 );
if ( $ns === self::NS_RDF ) {
if ( $tag === 'value' || $tag === 'resource' ) {
// resource is for url.
// value attribute is a weird way of just putting the contents.
$this->char( $this->xmlParser, $val );
}
} elseif ( isset( $this->items[$ns][$tag] ) ) {
if ( $this->mode[0] === self::MODE_SIMPLE ) {
throw new RuntimeException( __METHOD__
. " $ns:$tag found as attribute where not allowed" );
}
$this->saveValue( $ns, $tag, $val );
} else {
$this->logger->debug(
__METHOD__ . " Ignoring unrecognized element <$ns:$tag>.",
[ 'file' => $this->filename ]
);
}
}
}
/**
* Given an extracted value, save it to results array
*
* note also uses $this->ancestorStruct and
* $this->processingArray to determine what name to
* save the value under. (in addition to $tag).
*
* @param string $ns Namespace of tag this is for
* @param string $tag Tag name
* @param string $val Value to save
*/
private function saveValue( $ns, $tag, $val ): void {
$info =& $this->items[$ns][$tag];
$finalName = $info['map_name'] ?? $tag;
if ( isset( $info['validate'] ) ) {
if ( is_array( $info['validate'] ) ) {
$validate = $info['validate'];
} else {
$validator = new Validate( $this->logger );
$validate = [ $validator, $info['validate'] ];
}
if ( is_callable( $validate ) ) {
call_user_func_array( $validate, [ $info, &$val, true ] );
// the reasoning behind using &$val instead of using the return value
// is to be consistent between here and validating structures.
if ( $val === null ) {
$this->logger->info(
__METHOD__ . " <$ns:$tag> failed validation.",
[ 'file' => $this->filename ]
);
return;
}
} else {
$this->logger->warning(
__METHOD__ . " Validation function for $finalName (" .
get_class( $validate[0] ) . '::' . $validate[1] . '()) is not callable.',
[ 'file' => $this->filename ]
);
}
}
if ( $this->ancestorStruct && $this->processingArray ) {
// Aka both an array and a struct. ( self::MODE_BAGSTRUCT )
$this->results['xmp-' . $info['map_group']][$this->ancestorStruct][][$finalName] = $val;
} elseif ( $this->ancestorStruct ) {
$this->results['xmp-' . $info['map_group']][$this->ancestorStruct][$finalName] = $val;
} elseif ( $this->processingArray ) {
if ( $this->itemLang === false ) {
// normal array
$this->results['xmp-' . $info['map_group']][$finalName][] = $val;
} else {
// lang array.
$this->results['xmp-' . $info['map_group']][$finalName][$this->itemLang] = $val;
}
} else {
$this->results['xmp-' . $info['map_group']][$finalName] = $val;
}
}
}

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