/**
* Extract Metadata from a PDF file
*
* @since 2.10
*
* @param string full path to the desired file
*
* @return array ( 'xmp' => array( key => value ), 'pdf' => array( key => value ) ) for each metadata field, in string format
*/
public static function mla_extract_pdf_metadata($file_name)
{
$xmp = array();
$metadata = array();
self::$pdf_indirect_objects = NULL;
$chunksize = 16384;
if (!file_exists($file_name)) {
return array('xmp' => $xmp, 'pdf' => $metadata);
}
$filesize = filesize($file_name);
$file_offset = $chunksize < $filesize ? $filesize - $chunksize : 0;
$tail = file_get_contents($file_name, false, NULL, $file_offset);
//error_log( __LINE__ . " MLAPDF::mla_extract_pdf_metadata( {$file_name}, {$file_offset} ) tail = \r\n" . MLAData::mla_hex_dump( $tail ), 0 );
if (0 == $file_offset) {
$header = substr($tail, 0, 128);
} else {
$header = file_get_contents($file_name, false, NULL, 0, 128);
}
//error_log( __LINE__ . " MLAPDF::mla_extract_pdf_metadata( {$file_name}, {$file_offset} ) header = \r\n" . MLAData::mla_hex_dump( $header ), 0 );
if ('%PDF-' == substr($header, 0, 5)) {
$metadata['PDF_Version'] = substr($header, 1, 7);
$metadata['PDF_VersionNumber'] = substr($header, 5, 3);
}
/*
* Find the xref and (optional) trailer
*/
$match_count = preg_match_all('/startxref[\\x00-\\x20]+(\\d+)[\\x00-\\x20]+\\%\\%EOF/', $tail, $matches, PREG_OFFSET_CAPTURE);
if (0 == $match_count) {
/* translators: 1: ERROR tag 2: path and file */
error_log(sprintf(_x('%1$s: File "%2$s", startxref not found.', 'error_log', 'media-library-assistant'), __('ERROR', 'media-library-assistant'), $path), 0);
return array('xmp' => $xmp, 'pdf' => $metadata);
}
$startxref = (int) $matches[1][$match_count - 1][0];
$trailer_dictionaries = self::_extract_pdf_trailer($file_name, $startxref);
//error_log( __LINE__ . " MLAPDF::mla_extract_pdf_metadata trailer_dictionaries = " . var_export( $trailer_dictionaries, true ), 0 );
if (is_array($trailer_dictionaries)) {
$info_reference = NULL;
foreach ($trailer_dictionaries as $trailer_dictionary) {
if (isset($trailer_dictionary['Info'])) {
$info_reference = $trailer_dictionary['Info'];
break;
}
}
//error_log( __LINE__ . " MLAPDF::mla_extract_pdf_metadata info_reference = " . var_export( $info_reference, true ), 0 );
if (isset($info_reference)) {
$info_object = self::_find_pdf_indirect_dictionary($file_name, $info_reference['object'], $info_reference['generation']);
/*
* Handle single or multiple Info instances
*/
$info_objects = array();
if ($info_object) {
if (1 == $info_object['count']) {
$info_objects[] = $info_object;
} else {
for ($index = 0; $index < $info_object['count']; $index++) {
$info_objects[] = self::_find_pdf_indirect_dictionary($file_name, $info_reference['object'], $info_reference['generation'], $index);
}
}
}
//error_log( __LINE__ . " MLAPDF::mla_extract_pdf_metadata info_objects = " . var_export( $info_objects, true ), 0 );
foreach ($info_objects as $info_object) {
$info_dictionary = self::_parse_pdf_dictionary($info_object['content'], 0);
//error_log( __LINE__ . " MLAPDF::mla_extract_pdf_metadata info_dictionary = " . var_export( $info_dictionary, true ), 0 );
unset($info_dictionary['/length']);
foreach ($info_dictionary as $name => $value) {
if ('string' == $value['type']) {
$prefix = substr($value['value'], 0, 2);
if ('D:' == $prefix) {
$metadata[$name] = MLAData::mla_parse_pdf_date($value['value']);
} elseif (chr(0xfe) . chr(0xff) == $prefix) {
$metadata[$name] = self::_parse_pdf_UTF16BE($value['value']);
} else {
$metadata[$name] = $value['value'];
}
} else {
$metadata[$name] = $value['value'];
}
}
// each info entry
}
// foreach Info object
/*
* Remove spurious "Filter" dictionaries
*/
unset($metadata['Filter']);
unset($metadata['Length']);
unset($metadata['Length1']);
}
// found Info reference
//error_log( __LINE__ . ' MLAPDF::mla_extract_pdf_metadata pdf metadata = ' . var_export( $metadata, true ), 0 );
/*
* Look for XMP Metadata
*/
$root_reference = NULL;
//error_log( __LINE__ . " MLAPDF::mla_extract_pdf_metadata info_dictionary = " . var_export( $info_dictionary, true ), 0 );
foreach ($trailer_dictionaries as $trailer_dictionary) {
if (isset($trailer_dictionary['Root'])) {
$root_reference = $trailer_dictionary['Root'];
break;
}
}
//error_log( __LINE__ . " MLAPDF::mla_extract_pdf_metadata root_reference = " . var_export( $root_reference, true ), 0 );
if (isset($root_reference)) {
$root_object = self::_find_pdf_indirect_dictionary($file_name, $root_reference['object'], $root_reference['generation']);
//error_log( __LINE__ . " MLAPDF::mla_extract_pdf_metadata root_object = " . var_export( $root_object, true ), 0 );
if ($root_object) {
$root_dictionary = self::_parse_pdf_dictionary($root_object['content'], 0);
//error_log( __LINE__ . " MLAPDF::mla_extract_pdf_metadata root_dictionary = " . var_export( $root_dictionary, true ), 0 );
unset($root_dictionary['/length']);
if (isset($root_dictionary['Metadata'])) {
$xmp_object = self::_find_pdf_indirect_dictionary($file_name, $root_dictionary['Metadata']['object'], $root_dictionary['Metadata']['generation']);
//error_log( __LINE__ . " MLAPDF::mla_extract_pdf_metadata xmp_object = " . var_export( $xmp_object, true ), 0 );
$xmp = MLAData::mla_parse_xmp_metadata($file_name, $xmp_object['start'] + $xmp_object['length']);
if (is_array($xmp)) {
$metadata = array_merge($metadata, $xmp);
} else {
$xmp = array();
$xmp = MLAData::mla_parse_xmp_metadata($file_name, 0);
//error_log( __LINE__ . ' MLAPDF::mla_extract_pdf_metadata recovered xmp = ' . var_export( $xmp, true ), 0 );
}
}
// found Metadata reference
}
// found Root object
}
// found Root reference
}
// found trailer_dictionaries
//error_log( __LINE__ . ' MLAPDF::mla_extract_pdf_metadata pdf = ' . var_export( $metadata, true ), 0 );
//error_log( __LINE__ . ' MLAPDF::mla_extract_pdf_metadata xmp = ' . var_export( $xmp, true ), 0 );
return array('xmp' => $xmp, 'pdf' => $metadata);
}
