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Diffstat (limited to 'www/wiki/includes/media/PNGMetadataExtractor.php')
| -rw-r--r-- | www/wiki/includes/media/PNGMetadataExtractor.php | 428 |
1 files changed, 428 insertions, 0 deletions
diff --git a/www/wiki/includes/media/PNGMetadataExtractor.php b/www/wiki/includes/media/PNGMetadataExtractor.php new file mode 100644 index 00000000..78ed0bcd --- /dev/null +++ b/www/wiki/includes/media/PNGMetadataExtractor.php @@ -0,0 +1,428 @@ +<?php +/** + * PNG frame counter and metadata extractor. + * + * Slightly derived from GIFMetadataExtractor.php + * Deliberately not using MWExceptions to avoid external dependencies, encouraging + * redistribution. + * + * 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 + */ + +/** + * PNG frame counter. + * + * @ingroup Media + */ +class PNGMetadataExtractor { + /** @var string */ + private static $pngSig; + + /** @var int */ + private static $crcSize; + + /** @var array */ + private static $textChunks; + + const VERSION = 1; + const MAX_CHUNK_SIZE = 3145728; // 3 megabytes + + static function getMetadata( $filename ) { + self::$pngSig = pack( "C8", 137, 80, 78, 71, 13, 10, 26, 10 ); + self::$crcSize = 4; + /* based on list at http://owl.phy.queensu.ca/~phil/exiftool/TagNames/PNG.html#TextualData + * and https://www.w3.org/TR/PNG/#11keywords + */ + self::$textChunks = [ + 'xml:com.adobe.xmp' => 'xmp', + # Artist is unofficial. Author is the recommended + # keyword in the PNG spec. However some people output + # Artist so support both. + 'artist' => 'Artist', + 'model' => 'Model', + 'make' => 'Make', + 'author' => 'Artist', + 'comment' => 'PNGFileComment', + 'description' => 'ImageDescription', + 'title' => 'ObjectName', + 'copyright' => 'Copyright', + # Source as in original device used to make image + # not as in who gave you the image + 'source' => 'Model', + 'software' => 'Software', + 'disclaimer' => 'Disclaimer', + 'warning' => 'ContentWarning', + 'url' => 'Identifier', # Not sure if this is best mapping. Maybe WebStatement. + 'label' => 'Label', + 'creation time' => 'DateTimeDigitized', + /* Other potentially useful things - Document */ + ]; + + $frameCount = 0; + $loopCount = 1; + $text = []; + $duration = 0.0; + $bitDepth = 0; + $colorType = 'unknown'; + + if ( !$filename ) { + throw new Exception( __METHOD__ . ": No file name specified" ); + } elseif ( !file_exists( $filename ) || is_dir( $filename ) ) { + throw new Exception( __METHOD__ . ": File $filename does not exist" ); + } + + $fh = fopen( $filename, 'rb' ); + + if ( !$fh ) { + throw new Exception( __METHOD__ . ": Unable to open file $filename" ); + } + + // Check for the PNG header + $buf = fread( $fh, 8 ); + if ( $buf != self::$pngSig ) { + throw new Exception( __METHOD__ . ": Not a valid PNG file; header: $buf" ); + } + + // Read chunks + while ( !feof( $fh ) ) { + $buf = fread( $fh, 4 ); + if ( !$buf || strlen( $buf ) < 4 ) { + throw new Exception( __METHOD__ . ": Read error" ); + } + $chunk_size = unpack( "N", $buf )[1]; + + if ( $chunk_size < 0 ) { + throw new Exception( __METHOD__ . ": Chunk size too big for unpack" ); + } + + $chunk_type = fread( $fh, 4 ); + if ( !$chunk_type || strlen( $chunk_type ) < 4 ) { + throw new Exception( __METHOD__ . ": Read error" ); + } + + if ( $chunk_type == "IHDR" ) { + $buf = self::read( $fh, $chunk_size ); + if ( !$buf || strlen( $buf ) < $chunk_size ) { + throw new Exception( __METHOD__ . ": Read error" ); + } + $width = unpack( 'N', substr( $buf, 0, 4 ) )[1]; + $height = unpack( 'N', substr( $buf, 4, 4 ) )[1]; + $bitDepth = ord( substr( $buf, 8, 1 ) ); + // Detect the color type in British English as per the spec + // https://www.w3.org/TR/PNG/#11IHDR + switch ( ord( substr( $buf, 9, 1 ) ) ) { + case 0: + $colorType = 'greyscale'; + break; + case 2: + $colorType = 'truecolour'; + break; + case 3: + $colorType = 'index-coloured'; + break; + case 4: + $colorType = 'greyscale-alpha'; + break; + case 6: + $colorType = 'truecolour-alpha'; + break; + default: + $colorType = 'unknown'; + break; + } + } elseif ( $chunk_type == "acTL" ) { + $buf = fread( $fh, $chunk_size ); + if ( !$buf || strlen( $buf ) < $chunk_size || $chunk_size < 4 ) { + throw new Exception( __METHOD__ . ": Read error" ); + } + + $actl = unpack( "Nframes/Nplays", $buf ); + $frameCount = $actl['frames']; + $loopCount = $actl['plays']; + } elseif ( $chunk_type == "fcTL" ) { + $buf = self::read( $fh, $chunk_size ); + if ( !$buf || strlen( $buf ) < $chunk_size ) { + throw new Exception( __METHOD__ . ": Read error" ); + } + $buf = substr( $buf, 20 ); + if ( strlen( $buf ) < 4 ) { + throw new Exception( __METHOD__ . ": Read error" ); + } + + $fctldur = unpack( "ndelay_num/ndelay_den", $buf ); + if ( $fctldur['delay_den'] == 0 ) { + $fctldur['delay_den'] = 100; + } + if ( $fctldur['delay_num'] ) { + $duration += $fctldur['delay_num'] / $fctldur['delay_den']; + } + } elseif ( $chunk_type == "iTXt" ) { + // Extracts iTXt chunks, uncompressing if necessary. + $buf = self::read( $fh, $chunk_size ); + $items = []; + if ( preg_match( + '/^([^\x00]{1,79})\x00(\x00|\x01)\x00([^\x00]*)(.)[^\x00]*\x00(.*)$/Ds', + $buf, $items ) + ) { + /* $items[1] = text chunk name, $items[2] = compressed flag, + * $items[3] = lang code (or ""), $items[4]= compression type. + * $items[5] = content + */ + + // Theoretically should be case-sensitive, but in practise... + $items[1] = strtolower( $items[1] ); + if ( !isset( self::$textChunks[$items[1]] ) ) { + // Only extract textual chunks on our list. + fseek( $fh, self::$crcSize, SEEK_CUR ); + continue; + } + + $items[3] = strtolower( $items[3] ); + if ( $items[3] == '' ) { + // if no lang specified use x-default like in xmp. + $items[3] = 'x-default'; + } + + // if compressed + if ( $items[2] == "\x01" ) { + if ( function_exists( 'gzuncompress' ) && $items[4] === "\x00" ) { + Wikimedia\suppressWarnings(); + $items[5] = gzuncompress( $items[5] ); + Wikimedia\restoreWarnings(); + + if ( $items[5] === false ) { + // decompression failed + wfDebug( __METHOD__ . ' Error decompressing iTxt chunk - ' . $items[1] . "\n" ); + fseek( $fh, self::$crcSize, SEEK_CUR ); + continue; + } + } else { + wfDebug( __METHOD__ . ' Skipping compressed png iTXt chunk due to lack of zlib,' + . " or potentially invalid compression method\n" ); + fseek( $fh, self::$crcSize, SEEK_CUR ); + continue; + } + } + $finalKeyword = self::$textChunks[$items[1]]; + $text[$finalKeyword][$items[3]] = $items[5]; + $text[$finalKeyword]['_type'] = 'lang'; + } else { + // Error reading iTXt chunk + throw new Exception( __METHOD__ . ": Read error on iTXt chunk" ); + } + } elseif ( $chunk_type == 'tEXt' ) { + $buf = self::read( $fh, $chunk_size ); + + // In case there is no \x00 which will make explode fail. + if ( strpos( $buf, "\x00" ) === false ) { + throw new Exception( __METHOD__ . ": Read error on tEXt chunk" ); + } + + list( $keyword, $content ) = explode( "\x00", $buf, 2 ); + if ( $keyword === '' || $content === '' ) { + throw new Exception( __METHOD__ . ": Read error on tEXt chunk" ); + } + + // Theoretically should be case-sensitive, but in practise... + $keyword = strtolower( $keyword ); + if ( !isset( self::$textChunks[$keyword] ) ) { + // Don't recognize chunk, so skip. + fseek( $fh, self::$crcSize, SEEK_CUR ); + continue; + } + Wikimedia\suppressWarnings(); + $content = iconv( 'ISO-8859-1', 'UTF-8', $content ); + Wikimedia\restoreWarnings(); + + if ( $content === false ) { + throw new Exception( __METHOD__ . ": Read error (error with iconv)" ); + } + + $finalKeyword = self::$textChunks[$keyword]; + $text[$finalKeyword]['x-default'] = $content; + $text[$finalKeyword]['_type'] = 'lang'; + } elseif ( $chunk_type == 'zTXt' ) { + if ( function_exists( 'gzuncompress' ) ) { + $buf = self::read( $fh, $chunk_size ); + + // In case there is no \x00 which will make explode fail. + if ( strpos( $buf, "\x00" ) === false ) { + throw new Exception( __METHOD__ . ": Read error on zTXt chunk" ); + } + + list( $keyword, $postKeyword ) = explode( "\x00", $buf, 2 ); + if ( $keyword === '' || $postKeyword === '' ) { + throw new Exception( __METHOD__ . ": Read error on zTXt chunk" ); + } + // Theoretically should be case-sensitive, but in practise... + $keyword = strtolower( $keyword ); + + if ( !isset( self::$textChunks[$keyword] ) ) { + // Don't recognize chunk, so skip. + fseek( $fh, self::$crcSize, SEEK_CUR ); + continue; + } + $compression = substr( $postKeyword, 0, 1 ); + $content = substr( $postKeyword, 1 ); + if ( $compression !== "\x00" ) { + wfDebug( __METHOD__ . " Unrecognized compression method in zTXt ($keyword). Skipping.\n" ); + fseek( $fh, self::$crcSize, SEEK_CUR ); + continue; + } + + Wikimedia\suppressWarnings(); + $content = gzuncompress( $content ); + Wikimedia\restoreWarnings(); + + if ( $content === false ) { + // decompression failed + wfDebug( __METHOD__ . ' Error decompressing zTXt chunk - ' . $keyword . "\n" ); + fseek( $fh, self::$crcSize, SEEK_CUR ); + continue; + } + + Wikimedia\suppressWarnings(); + $content = iconv( 'ISO-8859-1', 'UTF-8', $content ); + Wikimedia\restoreWarnings(); + + if ( $content === false ) { + throw new Exception( __METHOD__ . ": Read error (error with iconv)" ); + } + + $finalKeyword = self::$textChunks[$keyword]; + $text[$finalKeyword]['x-default'] = $content; + $text[$finalKeyword]['_type'] = 'lang'; + } else { + wfDebug( __METHOD__ . " Cannot decompress zTXt chunk due to lack of zlib. Skipping.\n" ); + fseek( $fh, $chunk_size, SEEK_CUR ); + } + } elseif ( $chunk_type == 'tIME' ) { + // last mod timestamp. + if ( $chunk_size !== 7 ) { + throw new Exception( __METHOD__ . ": tIME wrong size" ); + } + $buf = self::read( $fh, $chunk_size ); + if ( !$buf || strlen( $buf ) < $chunk_size ) { + throw new Exception( __METHOD__ . ": Read error" ); + } + + // Note: spec says this should be UTC. + $t = unpack( "ny/Cm/Cd/Ch/Cmin/Cs", $buf ); + $strTime = sprintf( "%04d%02d%02d%02d%02d%02d", + $t['y'], $t['m'], $t['d'], $t['h'], + $t['min'], $t['s'] ); + + $exifTime = wfTimestamp( TS_EXIF, $strTime ); + + if ( $exifTime ) { + $text['DateTime'] = $exifTime; + } + } elseif ( $chunk_type == 'pHYs' ) { + // how big pixels are (dots per meter). + if ( $chunk_size !== 9 ) { + throw new Exception( __METHOD__ . ": pHYs wrong size" ); + } + + $buf = self::read( $fh, $chunk_size ); + if ( !$buf || strlen( $buf ) < $chunk_size ) { + throw new Exception( __METHOD__ . ": Read error" ); + } + + $dim = unpack( "Nwidth/Nheight/Cunit", $buf ); + if ( $dim['unit'] == 1 ) { + // Need to check for negative because php + // doesn't deal with super-large unsigned 32-bit ints well + if ( $dim['width'] > 0 && $dim['height'] > 0 ) { + // unit is meters + // (as opposed to 0 = undefined ) + $text['XResolution'] = $dim['width'] + . '/100'; + $text['YResolution'] = $dim['height'] + . '/100'; + $text['ResolutionUnit'] = 3; + // 3 = dots per cm (from Exif). + } + } + } elseif ( $chunk_type == "IEND" ) { + break; + } else { + fseek( $fh, $chunk_size, SEEK_CUR ); + } + fseek( $fh, self::$crcSize, SEEK_CUR ); + } + fclose( $fh ); + + if ( $loopCount > 1 ) { + $duration *= $loopCount; + } + + if ( isset( $text['DateTimeDigitized'] ) ) { + // Convert date format from rfc2822 to exif. + foreach ( $text['DateTimeDigitized'] as $name => &$value ) { + if ( $name === '_type' ) { + continue; + } + + // @todo FIXME: Currently timezones are ignored. + // possibly should be wfTimestamp's + // responsibility. (at least for numeric TZ) + $formatted = wfTimestamp( TS_EXIF, $value ); + if ( $formatted ) { + // Only change if we could convert the + // date. + // The png standard says it should be + // in rfc2822 format, but not required. + // In general for the exif stuff we + // prettify the date if we can, but we + // display as-is if we cannot or if + // it is invalid. + // So do the same here. + + $value = $formatted; + } + } + } + + return [ + 'frameCount' => $frameCount, + 'loopCount' => $loopCount, + 'duration' => $duration, + 'text' => $text, + 'bitDepth' => $bitDepth, + 'colorType' => $colorType, + ]; + } + + /** + * Read a chunk, checking to make sure its not too big. + * + * @param resource $fh The file handle + * @param int $size Size in bytes. + * @throws Exception If too big + * @return string The chunk. + */ + private static function read( $fh, $size ) { + if ( $size > self::MAX_CHUNK_SIZE ) { + throw new Exception( __METHOD__ . ': Chunk size of ' . $size . + ' too big. Max size is: ' . self::MAX_CHUNK_SIZE ); + } + + return fread( $fh, $size ); + } +} |