102a4f8a35
* Switch out raw Exceptions, mostly for InvalidArgumentExceptions.
* Fake exceptions triggered to give Monolog a backtrace are for
some reason "traditionally" RuntimeExceptions, instead, so we
continue to use that pattern in remaining locations.
* Just entirely give up on PostgresResultWrapper's resource vs. object mess.
* Drop now-unneeded false positive hits.
Change-Id: Id183ab60994cd9c6dc80401d4ce4de0ddf2b3da0
424 lines
12 KiB
PHP
424 lines
12 KiB
PHP
<?php
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/**
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* PNG frame counter and metadata extractor.
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*
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* Slightly derived from GIFMetadataExtractor.php
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* Deliberately not using MWExceptions to avoid external dependencies, encouraging
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* redistribution.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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* @ingroup Media
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*/
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use Wikimedia\AtEase\AtEase;
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/**
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* PNG frame counter.
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*
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* @ingroup Media
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*/
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class PNGMetadataExtractor {
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/** @var string */
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private static $pngSig;
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/** @var int */
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private static $crcSize;
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/** @var array */
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private static $textChunks;
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public const VERSION = 1;
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private const MAX_CHUNK_SIZE = 3_145_728; // 3 mebibytes
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public static function getMetadata( $filename ) {
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self::$pngSig = pack( "C8", 137, 80, 78, 71, 13, 10, 26, 10 );
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self::$crcSize = 4;
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/* based on list at http://owl.phy.queensu.ca/~phil/exiftool/TagNames/PNG.html#TextualData
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* and https://www.w3.org/TR/PNG/#11keywords
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*/
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self::$textChunks = [
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'xml:com.adobe.xmp' => 'xmp',
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# Artist is unofficial. Author is the recommended
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# keyword in the PNG spec. However some people output
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# Artist so support both.
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'artist' => 'Artist',
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'model' => 'Model',
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'make' => 'Make',
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'author' => 'Artist',
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'comment' => 'PNGFileComment',
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'description' => 'ImageDescription',
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'title' => 'ObjectName',
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'copyright' => 'Copyright',
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# Source as in original device used to make image
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# not as in who gave you the image
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'source' => 'Model',
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'software' => 'Software',
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'disclaimer' => 'Disclaimer',
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'warning' => 'ContentWarning',
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'url' => 'Identifier', # Not sure if this is best mapping. Maybe WebStatement.
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'label' => 'Label',
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'creation time' => 'DateTimeDigitized',
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/* Other potentially useful things - Document */
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];
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$frameCount = 0;
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$loopCount = 1;
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$text = [];
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$duration = 0.0;
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$width = 0;
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$height = 0;
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$bitDepth = 0;
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$colorType = 'unknown';
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if ( !$filename ) {
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throw new InvalidArgumentException( __METHOD__ . ": No file name specified" );
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}
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if ( !file_exists( $filename ) || is_dir( $filename ) ) {
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throw new InvalidArgumentException( __METHOD__ . ": File $filename does not exist" );
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}
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$fh = fopen( $filename, 'rb' );
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if ( !$fh ) {
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throw new InvalidArgumentException( __METHOD__ . ": Unable to open file $filename" );
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}
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// Check for the PNG header
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$buf = self::read( $fh, 8 );
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if ( $buf !== self::$pngSig ) {
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throw new InvalidArgumentException( __METHOD__ . ": Not a valid PNG file; header: $buf" );
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}
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// Read chunks
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while ( !feof( $fh ) ) {
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$buf = self::read( $fh, 4 );
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$chunk_size = unpack( "N", $buf )[1];
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if ( $chunk_size < 0 || $chunk_size > self::MAX_CHUNK_SIZE ) {
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wfDebug( __METHOD__ . ': Chunk size of ' . $chunk_size .
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' too big, skipping. Max size is: ' . self::MAX_CHUNK_SIZE );
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if ( fseek( $fh, 4 + $chunk_size + self::$crcSize, SEEK_CUR ) !== 0 ) {
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throw new InvalidArgumentException( __METHOD__ . ': seek error' );
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}
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continue;
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}
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$chunk_type = self::read( $fh, 4 );
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$buf = self::read( $fh, $chunk_size );
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$crc = self::read( $fh, self::$crcSize );
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$computed = crc32( $chunk_type . $buf );
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if ( pack( 'N', $computed ) !== $crc ) {
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wfDebug( __METHOD__ . ': chunk has invalid CRC, skipping' );
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continue;
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}
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if ( $chunk_type === "IHDR" ) {
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$width = unpack( 'N', substr( $buf, 0, 4 ) )[1];
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$height = unpack( 'N', substr( $buf, 4, 4 ) )[1];
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$bitDepth = ord( substr( $buf, 8, 1 ) );
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// Detect the color type in British English as per the spec
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// https://www.w3.org/TR/PNG/#11IHDR
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switch ( ord( substr( $buf, 9, 1 ) ) ) {
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case 0:
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$colorType = 'greyscale';
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break;
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case 2:
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$colorType = 'truecolour';
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break;
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case 3:
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$colorType = 'index-coloured';
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break;
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case 4:
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$colorType = 'greyscale-alpha';
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break;
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case 6:
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$colorType = 'truecolour-alpha';
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break;
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default:
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$colorType = 'unknown';
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break;
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}
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} elseif ( $chunk_type === "acTL" ) {
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if ( $chunk_size < 4 ) {
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wfDebug( __METHOD__ . ": acTL chunk too small" );
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continue;
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}
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$actl = unpack( "Nframes/Nplays", $buf );
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$frameCount = $actl['frames'];
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$loopCount = $actl['plays'];
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} elseif ( $chunk_type === "fcTL" ) {
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$buf = substr( $buf, 20 );
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if ( strlen( $buf ) < 4 ) {
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wfDebug( __METHOD__ . ": fcTL chunk too small" );
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continue;
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}
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$fctldur = unpack( "ndelay_num/ndelay_den", $buf );
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if ( $fctldur['delay_den'] == 0 ) {
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$fctldur['delay_den'] = 100;
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}
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if ( $fctldur['delay_num'] ) {
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$duration += $fctldur['delay_num'] / $fctldur['delay_den'];
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}
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} elseif ( $chunk_type === "iTXt" ) {
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// Extracts iTXt chunks, uncompressing if necessary.
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$items = [];
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if ( preg_match(
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'/^([^\x00]{1,79})\x00(\x00|\x01)\x00([^\x00]*)(.)[^\x00]*\x00(.*)$/Ds',
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$buf, $items )
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) {
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/* $items[1] = text chunk name, $items[2] = compressed flag,
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* $items[3] = lang code (or ""), $items[4]= compression type.
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* $items[5] = content
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*/
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// Theoretically should be case-sensitive, but in practise...
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$items[1] = strtolower( $items[1] );
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if ( !isset( self::$textChunks[$items[1]] ) ) {
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// Only extract textual chunks on our list.
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continue;
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}
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$items[3] = strtolower( $items[3] );
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if ( $items[3] == '' ) {
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// if no lang specified use x-default like in xmp.
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$items[3] = 'x-default';
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}
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// if compressed
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if ( $items[2] === "\x01" ) {
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if ( function_exists( 'gzuncompress' ) && $items[4] === "\x00" ) {
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AtEase::suppressWarnings();
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$items[5] = gzuncompress( $items[5] );
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AtEase::restoreWarnings();
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if ( $items[5] === false ) {
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// decompression failed
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wfDebug( __METHOD__ . ' Error decompressing iTxt chunk - ' . $items[1] );
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continue;
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}
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} else {
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wfDebug( __METHOD__ . ' Skipping compressed png iTXt chunk due to lack of zlib,'
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. " or potentially invalid compression method" );
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continue;
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}
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}
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$finalKeyword = self::$textChunks[$items[1]];
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$text[$finalKeyword][$items[3]] = $items[5];
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$text[$finalKeyword]['_type'] = 'lang';
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} else {
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// Error reading iTXt chunk
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wfDebug( __METHOD__ . ": Invalid iTXt chunk" );
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}
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} elseif ( $chunk_type === 'tEXt' ) {
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// In case there is no \x00 which will make explode fail.
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if ( strpos( $buf, "\x00" ) === false ) {
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wfDebug( __METHOD__ . ": Invalid tEXt chunk: no null byte" );
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continue;
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}
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[ $keyword, $content ] = explode( "\x00", $buf, 2 );
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if ( $keyword === '' ) {
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wfDebug( __METHOD__ . ": Empty tEXt keyword" );
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continue;
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}
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// Theoretically should be case-sensitive, but in practise...
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$keyword = strtolower( $keyword );
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if ( !isset( self::$textChunks[$keyword] ) ) {
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// Don't recognize chunk, so skip.
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continue;
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}
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AtEase::suppressWarnings();
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$content = iconv( 'ISO-8859-1', 'UTF-8', $content );
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AtEase::restoreWarnings();
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if ( $content === false ) {
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wfDebug( __METHOD__ . ": Read error (error with iconv)" );
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continue;
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}
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$finalKeyword = self::$textChunks[$keyword];
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$text[$finalKeyword]['x-default'] = $content;
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$text[$finalKeyword]['_type'] = 'lang';
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} elseif ( $chunk_type === 'zTXt' ) {
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if ( function_exists( 'gzuncompress' ) ) {
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// In case there is no \x00 which will make explode fail.
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if ( strpos( $buf, "\x00" ) === false ) {
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wfDebug( __METHOD__ . ": No null byte in zTXt chunk" );
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continue;
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}
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[ $keyword, $postKeyword ] = explode( "\x00", $buf, 2 );
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if ( $keyword === '' || $postKeyword === '' ) {
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wfDebug( __METHOD__ . ": Empty zTXt chunk" );
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continue;
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}
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// Theoretically should be case-sensitive, but in practise...
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$keyword = strtolower( $keyword );
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if ( !isset( self::$textChunks[$keyword] ) ) {
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// Don't recognize chunk, so skip.
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continue;
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}
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$compression = substr( $postKeyword, 0, 1 );
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$content = substr( $postKeyword, 1 );
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if ( $compression !== "\x00" ) {
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wfDebug( __METHOD__ . " Unrecognized compression method in zTXt ($keyword). Skipping." );
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continue;
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}
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AtEase::suppressWarnings();
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$content = gzuncompress( $content );
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AtEase::restoreWarnings();
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if ( $content === false ) {
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// decompression failed
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wfDebug( __METHOD__ . ' Error decompressing zTXt chunk - ' . $keyword );
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continue;
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}
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AtEase::suppressWarnings();
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$content = iconv( 'ISO-8859-1', 'UTF-8', $content );
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AtEase::restoreWarnings();
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if ( $content === false ) {
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wfDebug( __METHOD__ . ": iconv error in zTXt chunk" );
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continue;
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}
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$finalKeyword = self::$textChunks[$keyword];
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$text[$finalKeyword]['x-default'] = $content;
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$text[$finalKeyword]['_type'] = 'lang';
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} else {
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wfDebug( __METHOD__ . " Cannot decompress zTXt chunk due to lack of zlib. Skipping." );
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}
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} elseif ( $chunk_type === 'tIME' ) {
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// last mod timestamp.
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if ( $chunk_size !== 7 ) {
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wfDebug( __METHOD__ . ": tIME wrong size" );
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continue;
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}
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// Note: spec says this should be UTC.
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$t = unpack( "ny/Cm/Cd/Ch/Cmin/Cs", $buf );
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$strTime = sprintf( "%04d%02d%02d%02d%02d%02d",
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$t['y'], $t['m'], $t['d'], $t['h'],
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$t['min'], $t['s'] );
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$exifTime = wfTimestamp( TS_EXIF, $strTime );
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if ( $exifTime ) {
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$text['DateTime'] = $exifTime;
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}
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} elseif ( $chunk_type === 'pHYs' ) {
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// how big pixels are (dots per meter).
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if ( $chunk_size !== 9 ) {
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wfDebug( __METHOD__ . ": pHYs wrong size" );
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continue;
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}
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$dim = unpack( "Nwidth/Nheight/Cunit", $buf );
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if ( $dim['unit'] === 1 ) {
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// Need to check for negative because php
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// doesn't deal with super-large unsigned 32-bit ints well
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if ( $dim['width'] > 0 && $dim['height'] > 0 ) {
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// unit is meters
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// (as opposed to 0 = undefined )
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$text['XResolution'] = $dim['width']
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. '/100';
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$text['YResolution'] = $dim['height']
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. '/100';
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$text['ResolutionUnit'] = 3;
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// 3 = dots per cm (from Exif).
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}
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}
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} elseif ( $chunk_type === "IEND" ) {
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break;
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}
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}
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fclose( $fh );
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if ( $loopCount > 1 ) {
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$duration *= $loopCount;
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}
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if ( isset( $text['DateTimeDigitized'] ) ) {
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// Convert date format from rfc2822 to exif.
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foreach ( $text['DateTimeDigitized'] as $name => &$value ) {
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if ( $name === '_type' ) {
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continue;
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}
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// @todo FIXME: Currently timezones are ignored.
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// possibly should be wfTimestamp's
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// responsibility. (at least for numeric TZ)
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$formatted = wfTimestamp( TS_EXIF, $value );
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if ( $formatted ) {
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// Only change if we could convert the
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// date.
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// The png standard says it should be
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// in rfc2822 format, but not required.
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// In general for the exif stuff we
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// prettify the date if we can, but we
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// display as-is if we cannot or if
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// it is invalid.
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// So do the same here.
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$value = $formatted;
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}
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}
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}
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return [
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'width' => $width,
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'height' => $height,
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'frameCount' => $frameCount,
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'loopCount' => $loopCount,
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'duration' => $duration,
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'text' => $text,
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'bitDepth' => $bitDepth,
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'colorType' => $colorType,
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];
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}
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/**
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* Read a chunk, checking to make sure its not too big.
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*
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* @param resource $fh The file handle
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* @param int $size Size in bytes.
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* @throws Exception If too big
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* @return string The chunk.
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*/
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private static function read( $fh, $size ) {
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if ( $size === 0 ) {
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return '';
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}
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$result = fread( $fh, $size );
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if ( $result === false ) {
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throw new InvalidArgumentException( __METHOD__ . ': read error' );
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}
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if ( strlen( $result ) < $size ) {
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throw new InvalidArgumentException( __METHOD__ . ': unexpected end of file' );
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}
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return $result;
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}
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}
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