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+<?php
+/**
+ * Extraction of JPEG image metadata.
+ *
+ * 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
+ */
+
+/**
+ * Class for reading jpegs and extracting metadata.
+ * see also BitmapMetadataHandler.
+ *
+ * Based somewhat on GIFMetadataExtractor.
+ *
+ * @ingroup Media
+ */
+class JpegMetadataExtractor {
+ const MAX_JPEG_SEGMENTS = 200;
+
+ // the max segment is a sanity check.
+ // A jpeg file should never even remotely have
+ // that many segments. Your average file has about 10.
+
+ /** Function to extract metadata segments of interest from jpeg files
+ * based on GIFMetadataExtractor.
+ *
+ * we can almost use getimagesize to do this
+ * but gis doesn't support having multiple app1 segments
+ * and those can't extract xmp on files containing both exif and xmp data
+ *
+ * @param string $filename Name of jpeg file
+ * @return array Array of interesting segments.
+ * @throws MWException If given invalid file.
+ */
+ static function segmentSplitter( $filename ) {
+ $showXMP = XMPReader::isSupported();
+
+ $segmentCount = 0;
+
+ $segments = [
+ 'XMP_ext' => [],
+ 'COM' => [],
+ 'PSIR' => [],
+ ];
+
+ if ( !$filename ) {
+ throw new MWException( "No filename specified for " . __METHOD__ );
+ }
+ if ( !file_exists( $filename ) || is_dir( $filename ) ) {
+ throw new MWException( "Invalid file $filename passed to " . __METHOD__ );
+ }
+
+ $fh = fopen( $filename, "rb" );
+
+ if ( !$fh ) {
+ throw new MWException( "Could not open file $filename" );
+ }
+
+ $buffer = fread( $fh, 2 );
+ if ( $buffer !== "\xFF\xD8" ) {
+ throw new MWException( "Not a jpeg, no SOI" );
+ }
+ while ( !feof( $fh ) ) {
+ $buffer = fread( $fh, 1 );
+ $segmentCount++;
+ if ( $segmentCount > self::MAX_JPEG_SEGMENTS ) {
+ // this is just a sanity check
+ throw new MWException( 'Too many jpeg segments. Aborting' );
+ }
+ while ( $buffer !== "\xFF" && !feof( $fh ) ) {
+ // In theory JPEG files are not allowed to contain anything between the sections,
+ // but in practice they sometimes do. It's customary to ignore the garbage data.
+ $buffer = fread( $fh, 1 );
+ }
+
+ $buffer = fread( $fh, 1 );
+ while ( $buffer === "\xFF" && !feof( $fh ) ) {
+ // Skip through any 0xFF padding bytes.
+ $buffer = fread( $fh, 1 );
+ }
+ if ( $buffer === "\xFE" ) {
+ // COM section -- file comment
+ // First see if valid utf-8,
+ // if not try to convert it to windows-1252.
+ $com = $oldCom = trim( self::jpegExtractMarker( $fh ) );
+ UtfNormal\Validator::quickIsNFCVerify( $com );
+ // turns $com to valid utf-8.
+ // thus if no change, its utf-8, otherwise its something else.
+ if ( $com !== $oldCom ) {
+ Wikimedia\suppressWarnings();
+ $com = $oldCom = iconv( 'windows-1252', 'UTF-8//IGNORE', $oldCom );
+ Wikimedia\restoreWarnings();
+ }
+ // Try it again, if its still not a valid string, then probably
+ // binary junk or some really weird encoding, so don't extract.
+ UtfNormal\Validator::quickIsNFCVerify( $com );
+ if ( $com === $oldCom ) {
+ $segments["COM"][] = $oldCom;
+ } else {
+ wfDebug( __METHOD__ . " Ignoring JPEG comment as is garbage.\n" );
+ }
+ } elseif ( $buffer === "\xE1" ) {
+ // APP1 section (Exif, XMP, and XMP extended)
+ // only extract if XMP is enabled.
+ $temp = self::jpegExtractMarker( $fh );
+ // check what type of app segment this is.
+ if ( substr( $temp, 0, 29 ) === "http://ns.adobe.com/xap/1.0/\x00" && $showXMP ) {
+ $segments["XMP"] = substr( $temp, 29 );
+ } elseif ( substr( $temp, 0, 35 ) === "http://ns.adobe.com/xmp/extension/\x00" && $showXMP ) {
+ $segments["XMP_ext"][] = substr( $temp, 35 );
+ } elseif ( substr( $temp, 0, 29 ) === "XMP\x00://ns.adobe.com/xap/1.0/\x00" && $showXMP ) {
+ // Some images (especially flickr images) seem to have this.
+ // I really have no idea what the deal is with them, but
+ // whatever...
+ $segments["XMP"] = substr( $temp, 29 );
+ wfDebug( __METHOD__ . ' Found XMP section with wrong app identifier '
+ . "Using anyways.\n" );
+ } elseif ( substr( $temp, 0, 6 ) === "Exif\0\0" ) {
+ // Just need to find out what the byte order is.
+ // because php's exif plugin sucks...
+ // This is a II for little Endian, MM for big. Not a unicode BOM.
+ $byteOrderMarker = substr( $temp, 6, 2 );
+ if ( $byteOrderMarker === 'MM' ) {
+ $segments['byteOrder'] = 'BE';
+ } elseif ( $byteOrderMarker === 'II' ) {
+ $segments['byteOrder'] = 'LE';
+ } else {
+ wfDebug( __METHOD__ . " Invalid byte ordering?!\n" );
+ }
+ }
+ } elseif ( $buffer === "\xED" ) {
+ // APP13 - PSIR. IPTC and some photoshop stuff
+ $temp = self::jpegExtractMarker( $fh );
+ if ( substr( $temp, 0, 14 ) === "Photoshop 3.0\x00" ) {
+ $segments["PSIR"][] = $temp;
+ }
+ } elseif ( $buffer === "\xD9" || $buffer === "\xDA" ) {
+ // EOI - end of image or SOS - start of scan. either way we're past any interesting segments
+ return $segments;
+ } else {
+ // segment we don't care about, so skip
+ $size = wfUnpack( "nint", fread( $fh, 2 ), 2 );
+ if ( $size['int'] < 2 ) {
+ throw new MWException( "invalid marker size in jpeg" );
+ }
+ // Note it's possible to seek beyond end of file if truncated.
+ // fseek doesn't report a failure in this case.
+ fseek( $fh, $size['int'] - 2, SEEK_CUR );
+ }
+ }
+ // shouldn't get here.
+ throw new MWException( "Reached end of jpeg file unexpectedly" );
+ }
+
+ /**
+ * Helper function for jpegSegmentSplitter
+ * @param resource &$fh File handle for JPEG file
+ * @throws MWException
+ * @return string Data content of segment.
+ */
+ private static function jpegExtractMarker( &$fh ) {
+ $size = wfUnpack( "nint", fread( $fh, 2 ), 2 );
+ if ( $size['int'] < 2 ) {
+ throw new MWException( "invalid marker size in jpeg" );
+ }
+ if ( $size['int'] === 2 ) {
+ // fread( ..., 0 ) generates a warning
+ return '';
+ }
+ $segment = fread( $fh, $size['int'] - 2 );
+ if ( strlen( $segment ) !== $size['int'] - 2 ) {
+ throw new MWException( "Segment shorter than expected" );
+ }
+
+ return $segment;
+ }
+
+ /**
+ * This reads the photoshop image resource.
+ * Currently it only compares the iptc/iim hash
+ * with the stored hash, which is used to determine the precedence
+ * of the iptc data. In future it may extract some other info, like
+ * url of copyright license.
+ *
+ * This should generally be called by BitmapMetadataHandler::doApp13()
+ *
+ * @param string $app13 Photoshop psir app13 block from jpg.
+ * @throws MWException (It gets caught next level up though)
+ * @return string If the iptc hash is good or not. One of 'iptc-no-hash',
+ * 'iptc-good-hash', 'iptc-bad-hash'.
+ */
+ public static function doPSIR( $app13 ) {
+ if ( !$app13 ) {
+ throw new MWException( "No App13 segment given" );
+ }
+ // First compare hash with real thing
+ // 0x404 contains IPTC, 0x425 has hash
+ // This is used to determine if the iptc is newer than
+ // the xmp data, as xmp programs update the hash,
+ // where non-xmp programs don't.
+
+ $offset = 14; // skip past PHOTOSHOP 3.0 identifier. should already be checked.
+ $appLen = strlen( $app13 );
+ $realHash = "";
+ $recordedHash = "";
+
+ // the +12 is the length of an empty item.
+ while ( $offset + 12 <= $appLen ) {
+ $valid = true;
+ if ( substr( $app13, $offset, 4 ) !== '8BIM' ) {
+ // its supposed to be 8BIM
+ // but apparently sometimes isn't esp. in
+ // really old jpg's
+ $valid = false;
+ }
+ $offset += 4;
+ $id = substr( $app13, $offset, 2 );
+ // id is a 2 byte id number which identifies
+ // the piece of info this record contains.
+
+ $offset += 2;
+
+ // some record types can contain a name, which
+ // is a pascal string 0-padded to be an even
+ // number of bytes. Most times (and any time
+ // we care) this is empty, making it two null bytes.
+
+ $lenName = ord( substr( $app13, $offset, 1 ) ) + 1;
+ // we never use the name so skip it. +1 for length byte
+ if ( $lenName % 2 == 1 ) {
+ $lenName++;
+ } // pad to even.
+ $offset += $lenName;
+
+ // now length of data (unsigned long big endian)
+ $lenData = wfUnpack( 'Nlen', substr( $app13, $offset, 4 ), 4 );
+ // PHP can take issue with very large unsigned ints and make them negative.
+ // Which should never ever happen, as this has to be inside a segment
+ // which is limited to a 16 bit number.
+ if ( $lenData['len'] < 0 ) {
+ throw new MWException( "Too big PSIR (" . $lenData['len'] . ')' );
+ }
+
+ $offset += 4; // 4bytes length field;
+
+ // this should not happen, but check.
+ if ( $lenData['len'] + $offset > $appLen ) {
+ throw new MWException( "PSIR data too long. (item length=" . $lenData['len']
+ . "; offset=$offset; total length=$appLen)" );
+ }
+
+ if ( $valid ) {
+ switch ( $id ) {
+ case "\x04\x04":
+ // IPTC block
+ $realHash = md5( substr( $app13, $offset, $lenData['len'] ), true );
+ break;
+ case "\x04\x25":
+ $recordedHash = substr( $app13, $offset, $lenData['len'] );
+ break;
+ }
+ }
+
+ // if odd, add 1 to length to account for
+ // null pad byte.
+ if ( $lenData['len'] % 2 == 1 ) {
+ $lenData['len']++;
+ }
+ $offset += $lenData['len'];
+ }
+
+ if ( !$realHash || !$recordedHash ) {
+ return 'iptc-no-hash';
+ } elseif ( $realHash === $recordedHash ) {
+ return 'iptc-good-hash';
+ } else { /*$realHash !== $recordedHash */
+ return 'iptc-bad-hash';
+ }
+ }
+}
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