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[mediawiki.git] / includes / media / DjVu.php

<?php
/**
 * Handler for DjVu 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
 */

/**
 * Handler for DjVu images
 *
 * @ingroup Media
 */
class DjVuHandler extends ImageHandler {
        const EXPENSIVE_SIZE_LIMIT = 10485760; // 10MiB

        /**
         * @return bool
         */
        function isEnabled() {
                global $wgDjvuRenderer, $wgDjvuDump, $wgDjvuToXML;
                if ( !$wgDjvuRenderer || ( !$wgDjvuDump && !$wgDjvuToXML ) ) {
                        wfDebug( "DjVu is disabled, please set \$wgDjvuRenderer and \$wgDjvuDump\n" );

                        return false;
                } else {
                        return true;
                }
        }

        /**
         * @param File $file
         * @return bool
         */
        public function mustRender( $file ) {
                return true;
        }

        /**
         * True if creating thumbnails from the file is large or otherwise resource-intensive.
         * @param File $file
         * @return bool
         */
        public function isExpensiveToThumbnail( $file ) {
                return $file->getSize() > static::EXPENSIVE_SIZE_LIMIT;
        }

        /**
         * @param File $file
         * @return bool
         */
        public function isMultiPage( $file ) {
                return true;
        }

        /**
         * @return array
         */
        public function getParamMap() {
                return [
                        'img_width' => 'width',
                        'img_page' => 'page',
                ];
        }

        /**
         * @param string $name
         * @param mixed $value
         * @return bool
         */
        public function validateParam( $name, $value ) {
                if ( $name === 'page' && trim( $value ) !== (string)intval( $value ) ) {
                        // Extra junk on the end of page, probably actually a caption
                        // e.g. [[File:Foo.djvu|thumb|Page 3 of the document shows foo]]
                        return false;
                }
                if ( in_array( $name, [ 'width', 'height', 'page' ] ) ) {
                        if ( $value <= 0 ) {
                                return false;
                        } else {
                                return true;
                        }
                } else {
                        return false;
                }
        }

        /**
         * @param array $params
         * @return bool|string
         */
        public function makeParamString( $params ) {
                $page = isset( $params['page'] ) ? $params['page'] : 1;
                if ( !isset( $params['width'] ) ) {
                        return false;
                }

                return "page{$page}-{$params['width']}px";
        }

        /**
         * @param string $str
         * @return array|bool
         */
        public function parseParamString( $str ) {
                $m = false;
                if ( preg_match( '/^page(\d+)-(\d+)px$/', $str, $m ) ) {
                        return [ 'width' => $m[2], 'page' => $m[1] ];
                } else {
                        return false;
                }
        }

        /**
         * @param array $params
         * @return array
         */
        function getScriptParams( $params ) {
                return [
                        'width' => $params['width'],
                        'page' => $params['page'],
                ];
        }

        /**
         * @param File $image
         * @param string $dstPath
         * @param string $dstUrl
         * @param array $params
         * @param int $flags
         * @return MediaTransformError|ThumbnailImage|TransformParameterError
         */
        function doTransform( $image, $dstPath, $dstUrl, $params, $flags = 0 ) {
                global $wgDjvuRenderer, $wgDjvuPostProcessor;

                if ( !$this->normaliseParams( $image, $params ) ) {
                        return new TransformParameterError( $params );
                }
                $width = $params['width'];
                $height = $params['height'];
                $page = $params['page'];

                if ( $flags & self::TRANSFORM_LATER ) {
                        $params = [
                                'width' => $width,
                                'height' => $height,
                                'page' => $page
                        ];

                        return new ThumbnailImage( $image, $dstUrl, $dstPath, $params );
                }

                if ( !wfMkdirParents( dirname( $dstPath ), null, __METHOD__ ) ) {
                        return new MediaTransformError(
                                'thumbnail_error',
                                $width,
                                $height,
                                wfMessage( 'thumbnail_dest_directory' )
                        );
                }

                // Get local copy source for shell scripts
                // Thumbnail extraction is very inefficient for large files.
                // Provide a way to pool count limit the number of downloaders.
                if ( $image->getSize() >= 1e7 ) { // 10MB
                        $work = new PoolCounterWorkViaCallback( 'GetLocalFileCopy', sha1( $image->getName() ),
                                [
                                        'doWork' => function () use ( $image ) {
                                                return $image->getLocalRefPath();
                                        }
                                ]
                        );
                        $srcPath = $work->execute();
                } else {
                        $srcPath = $image->getLocalRefPath();
                }

                if ( $srcPath === false ) { // Failed to get local copy
                        wfDebugLog( 'thumbnail',
                                sprintf( 'Thumbnail failed on %s: could not get local copy of "%s"',
                                        wfHostname(), $image->getName() ) );

                        return new MediaTransformError( 'thumbnail_error',
                                $params['width'], $params['height'],
                                wfMessage( 'filemissing' )
                        );
                }

                # Use a subshell (brackets) to aggregate stderr from both pipeline commands
                # before redirecting it to the overall stdout. This works in both Linux and Windows XP.
                $cmd = '(' . wfEscapeShellArg(
                        $wgDjvuRenderer,
                        "-format=ppm",
                        "-page={$page}",
                        "-size={$params['physicalWidth']}x{$params['physicalHeight']}",
                        $srcPath );
                if ( $wgDjvuPostProcessor ) {
                        $cmd .= " | {$wgDjvuPostProcessor}";
                }
                $cmd .= ' > ' . wfEscapeShellArg( $dstPath ) . ') 2>&1';
                wfDebug( __METHOD__ . ": $cmd\n" );
                $retval = '';
                $err = wfShellExec( $cmd, $retval );

                $removed = $this->removeBadFile( $dstPath, $retval );
                if ( $retval != 0 || $removed ) {
                        $this->logErrorForExternalProcess( $retval, $err, $cmd );
                        return new MediaTransformError( 'thumbnail_error', $width, $height, $err );
                } else {
                        $params = [
                                'width' => $width,
                                'height' => $height,
                                'page' => $page
                        ];

                        return new ThumbnailImage( $image, $dstUrl, $dstPath, $params );
                }
        }

        /**
         * Cache an instance of DjVuImage in an Image object, return that instance
         *
         * @param File|FSFile $image
         * @param string $path
         * @return DjVuImage
         */
        function getDjVuImage( $image, $path ) {
                if ( !$image ) {
                        $deja = new DjVuImage( $path );
                } elseif ( !isset( $image->dejaImage ) ) {
                        $deja = $image->dejaImage = new DjVuImage( $path );
                } else {
                        $deja = $image->dejaImage;
                }

                return $deja;
        }

        /**
         * Get metadata, unserializing it if neccessary.
         *
         * @param File $file The DjVu file in question
         * @return string XML metadata as a string.
         * @throws MWException
         */
        private function getUnserializedMetadata( File $file ) {
                $metadata = $file->getMetadata();
                if ( substr( $metadata, 0, 3 ) === '<?xml' ) {
                        // Old style. Not serialized but instead just a raw string of XML.
                        return $metadata;
                }

                MediaWiki\suppressWarnings();
                $unser = unserialize( $metadata );
                MediaWiki\restoreWarnings();
                if ( is_array( $unser ) ) {
                        if ( isset( $unser['error'] ) ) {
                                return false;
                        } elseif ( isset( $unser['xml'] ) ) {
                                return $unser['xml'];
                        } else {
                                // Should never ever reach here.
                                throw new MWException( "Error unserializing DjVu metadata." );
                        }
                }

                // unserialize failed. Guess it wasn't really serialized after all,
                return $metadata;
        }

        /**
         * Cache a document tree for the DjVu XML metadata
         * @param File $image
         * @param bool $gettext DOCUMENT (Default: false)
         * @return bool|SimpleXMLElement
         */
        public function getMetaTree( $image, $gettext = false ) {
                if ( $gettext && isset( $image->djvuTextTree ) ) {
                        return $image->djvuTextTree;
                }
                if ( !$gettext && isset( $image->dejaMetaTree ) ) {
                        return $image->dejaMetaTree;
                }

                $metadata = $this->getUnserializedMetadata( $image );
                if ( !$this->isMetadataValid( $image, $metadata ) ) {
                        wfDebug( "DjVu XML metadata is invalid or missing, should have been fixed in upgradeRow\n" );

                        return false;
                }

                MediaWiki\suppressWarnings();
                try {
                        // Set to false rather than null to avoid further attempts
                        $image->dejaMetaTree = false;
                        $image->djvuTextTree = false;
                        $tree = new SimpleXMLElement( $metadata, LIBXML_PARSEHUGE );
                        if ( $tree->getName() == 'mw-djvu' ) {
                                /** @var SimpleXMLElement $b */
                                foreach ( $tree->children() as $b ) {
                                        if ( $b->getName() == 'DjVuTxt' ) {
                                                // @todo File::djvuTextTree and File::dejaMetaTree are declared
                                                // dynamically. Add a public File::$data to facilitate this?
                                                $image->djvuTextTree = $b;
                                        } elseif ( $b->getName() == 'DjVuXML' ) {
                                                $image->dejaMetaTree = $b;
                                        }
                                }
                        } else {
                                $image->dejaMetaTree = $tree;
                        }
                } catch ( Exception $e ) {
                        wfDebug( "Bogus multipage XML metadata on '{$image->getName()}'\n" );
                }
                MediaWiki\restoreWarnings();
                if ( $gettext ) {
                        return $image->djvuTextTree;
                } else {
                        return $image->dejaMetaTree;
                }
        }

        function getImageSize( $image, $path ) {
                return $this->getDjVuImage( $image, $path )->getImageSize();
        }

        function getThumbType( $ext, $mime, $params = null ) {
                global $wgDjvuOutputExtension;
                static $mime;
                if ( !isset( $mime ) ) {
                        $magic = MimeMagic::singleton();
                        $mime = $magic->guessTypesForExtension( $wgDjvuOutputExtension );
                }

                return [ $wgDjvuOutputExtension, $mime ];
        }

        function getMetadata( $image, $path ) {
                wfDebug( "Getting DjVu metadata for $path\n" );

                $xml = $this->getDjVuImage( $image, $path )->retrieveMetaData();
                if ( $xml === false ) {
                        // Special value so that we don't repetitively try and decode a broken file.
                        return serialize( [ 'error' => 'Error extracting metadata' ] );
                } else {
                        return serialize( [ 'xml' => $xml ] );
                }
        }

        function getMetadataType( $image ) {
                return 'djvuxml';
        }

        function isMetadataValid( $image, $metadata ) {
                return !empty( $metadata ) && $metadata != serialize( [] );
        }

        function pageCount( File $image ) {
                $info = $this->getDimensionInfo( $image );

                return $info ? $info['pageCount'] : false;
        }

        function getPageDimensions( File $image, $page ) {
                $index = $page - 1; // MW starts pages at 1

                $info = $this->getDimensionInfo( $image );
                if ( $info && isset( $info['dimensionsByPage'][$index] ) ) {
                        return $info['dimensionsByPage'][$index];
                }

                return false;
        }

        protected function getDimensionInfo( File $file ) {
                $cache = ObjectCache::getMainWANInstance();
                return $cache->getWithSetCallback(
                        $cache->makeKey( 'file-djvu', 'dimensions', $file->getSha1() ),
                        $cache::TTL_INDEFINITE,
                        function () use ( $file ) {
                                $tree = $this->getMetaTree( $file );
                                if ( !$tree ) {
                                        return false;
                                }

                                $dimsByPage = [];
                                $count = count( $tree->xpath( '//OBJECT' ) );
                                for ( $i = 0; $i < $count; $i++ ) {
                                        $o = $tree->BODY[0]->OBJECT[$i];
                                        if ( $o ) {
                                                $dimsByPage[$i] = [
                                                        'width' => (int)$o['width'],
                                                        'height' => (int)$o['height'],
                                                ];
                                        } else {
                                                $dimsByPage[$i] = false;
                                        }
                                }

                                return [ 'pageCount' => $count, 'dimensionsByPage' => $dimsByPage ];
                        },
                        [ 'pcTTL' => $cache::TTL_INDEFINITE ]
                );
        }

        /**
         * @param File $image
         * @param int $page Page number to get information for
         * @return bool|string Page text or false when no text found.
         */
        function getPageText( File $image, $page ) {
                $tree = $this->getMetaTree( $image, true );
                if ( !$tree ) {
                        return false;
                }

                $o = $tree->BODY[0]->PAGE[$page - 1];
                if ( $o ) {
                        $txt = $o['value'];

                        return $txt;
                } else {
                        return false;
                }
        }
}