DjVu.php

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<?php
class DjVuHandler extends ImageHandler {
    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;
        }
    }

    function mustRender( $file ) {
        return true;
    }

    function isMultiPage( $file ) {
        return true;
    }

    function getParamMap() {
        return array(
            'img_width' => 'width',
            'img_page' => 'page',
        );
    }

    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, array( 'width', 'height', 'page' ) ) ) {
            if ( $value <= 0 ) {
                return false;
            } else {
                return true;
            }
        } else {
            return false;
        }
    }

    function makeParamString( $params ) {
        $page = isset( $params['page'] ) ? $params['page'] : 1;
        if ( !isset( $params['width'] ) ) {
            return false;
        }

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

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

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

    function doTransform( $image, $dstPath, $dstUrl, $params, $flags = 0 ) {
        global $wgDjvuRenderer, $wgDjvuPostProcessor;

        // Fetch XML and check it, to give a more informative error message than the one which
        // normaliseParams will inevitably give.
        $xml = $image->getMetadata();
        if ( !$xml ) {
            $width = isset( $params['width'] ) ? $params['width'] : 0;
            $height = isset( $params['height'] ) ? $params['height'] : 0;

            return new MediaTransformError( 'thumbnail_error', $width, $height,
                wfMessage( 'djvu_no_xml' )->text() );
        }

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

        if ( $flags & self::TRANSFORM_LATER ) {
            $params = array(
                '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' )->text()
            );
        }

        // 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() ),
                array(
                    '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' )->text()
            );
        }

        # 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';
        wfProfileIn( 'ddjvu' );
        wfDebug( __METHOD__ . ": $cmd\n" );
        $retval = '';
        $err = wfShellExec( $cmd, $retval );
        wfProfileOut( 'ddjvu' );

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

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

    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;
    }

    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;
        }

        wfSuppressWarnings();
        $unser = unserialize( $metadata );
        wfRestoreWarnings();
        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;
    }

    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;
        }
        wfProfileIn( __METHOD__ );

        wfSuppressWarnings();
        try {
            // Set to false rather than null to avoid further attempts
            $image->dejaMetaTree = false;
            $image->djvuTextTree = false;
            $tree = new SimpleXMLElement( $metadata );
            if ( $tree->getName() == 'mw-djvu' ) {
                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" );
        }
        wfRestoreWarnings();
        wfProfileOut( __METHOD__ );
        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 array( $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( array( 'error' => 'Error extracting metadata' ) );
        } else {
            return serialize( array( 'xml' => $xml ) );
        }
    }

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

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

    function pageCount( $image ) {
        $tree = $this->getMetaTree( $image );
        if ( !$tree ) {
            return false;
        }

        return count( $tree->xpath( '//OBJECT' ) );
    }

    function getPageDimensions( $image, $page ) {
        $tree = $this->getMetaTree( $image );
        if ( !$tree ) {
            return false;
        }

        $o = $tree->BODY[0]->OBJECT[$page - 1];
        if ( $o ) {
            return array(
                'width' => intval( $o['width'] ),
                'height' => intval( $o['height'] )
            );
        } else {
            return false;
        }
    }

    function getPageText( $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;
        }
    }
}