* @copyright Copyright 2010 Wikimedia Foundation * @license http://www.apache.org/licenses/LICENSE-2.0 */ /** * Transforms CSS data * * This class provides minification, URL remapping, URL extracting, and data-URL embedding. */ class CSSMin { /* Constants */ /** @var string Strip marker for comments. **/ const PLACEHOLDER = "\x7fPLACEHOLDER\x7f"; /** * Internet Explorer data URI length limit. See encodeImageAsDataURI(). */ const DATA_URI_SIZE_LIMIT = 32768; const URL_REGEX = 'url\(\s*[\'"]?(?P[^\?\)\'"]*?)(?P\?[^\)\'"]*?|)[\'"]?\s*\)'; const EMBED_REGEX = '\/\*\s*\@embed\s*\*\/'; const COMMENT_REGEX = '\/\*.*?\*\/'; /* Protected Static Members */ /** @var array List of common image files extensions and MIME-types */ protected static $mimeTypes = array( 'gif' => 'image/gif', 'jpe' => 'image/jpeg', 'jpeg' => 'image/jpeg', 'jpg' => 'image/jpeg', 'png' => 'image/png', 'tif' => 'image/tiff', 'tiff' => 'image/tiff', 'xbm' => 'image/x-xbitmap', 'svg' => 'image/svg+xml', ); /* Static Methods */ /** * Gets a list of local file paths which are referenced in a CSS style sheet. * * If you wish non-existent files to be listed too, use getAllLocalFileReferences(). * * For backwards-compatibility, if the second parameter is not given or null, * this function will return an empty array instead of erroring out. * * @param string $source CSS stylesheet source to process * @param string $path File path where the source was read from * @return array List of local file references */ public static function getLocalFileReferences( $source, $path = null ) { if ( $path === null ) { return array(); } $files = self::getAllLocalFileReferences( $source, $path ); // Skip non-existent files $files = array_filter( $files, function ( $file ) { return file_exists( $file ); } ); return $files; } /** * Gets a list of local file paths which are referenced in a CSS style sheet, including * non-existent files. * * @param string $source CSS stylesheet source to process * @param string $path File path where the source was read from * @return array List of local file references */ public static function getAllLocalFileReferences( $source, $path ) { $stripped = preg_replace( '/' . self::COMMENT_REGEX . '/s', '', $source ); $path = rtrim( $path, '/' ) . '/'; $files = array(); $rFlags = PREG_OFFSET_CAPTURE | PREG_SET_ORDER; if ( preg_match_all( '/' . self::URL_REGEX . '/', $stripped, $matches, $rFlags ) ) { foreach ( $matches as $match ) { $url = $match['file'][0]; // Skip fully-qualified and protocol-relative URLs and data URIs if ( substr( $url, 0, 2 ) === '//' || parse_url( $url, PHP_URL_SCHEME ) ) { break; } $files[] = $path . $url; } } return $files; } /** * Encode an image file as a data URI. * * If the image file has a suitable MIME type and size, encode it as a data URI, base64-encoded * for binary files or just percent-encoded otherwise. Return false if the image type is * unfamiliar or file exceeds the size limit. * * @param string $file Image file to encode. * @param string|null $type File's MIME type or null. If null, CSSMin will * try to autodetect the type. * @param bool $ie8Compat By default, a data URI will only be produced if it can be made short * enough to fit in Internet Explorer 8 (and earlier) URI length limit (32,768 bytes). Pass * `false` to remove this limitation. * @return string|bool Image contents encoded as a data URI or false. */ public static function encodeImageAsDataURI( $file, $type = null, $ie8Compat = true ) { // Fast-fail for files that definitely exceed the maximum data URI length if ( $ie8Compat && filesize( $file ) >= self::DATA_URI_SIZE_LIMIT ) { return false; } if ( $type === null ) { $type = self::getMimeType( $file ); } if ( !$type ) { return false; } return self::encodeStringAsDataURI( file_get_contents( $file ), $type, $ie8Compat ); } /** * Encode file contents as a data URI with chosen MIME type. * * The URI will be base64-encoded for binary files or just percent-encoded otherwise. * * @since 1.25 * * @param string $contents File contents to encode. * @param string $type File's MIME type. * @param bool $ie8Compat See encodeImageAsDataURI(). * @return string|bool Image contents encoded as a data URI or false. */ public static function encodeStringAsDataURI( $contents, $type, $ie8Compat = true ) { // Try #1: Non-encoded data URI // The regular expression matches ASCII whitespace and printable characters. if ( preg_match( '/^[\r\n\t\x20-\x7e]+$/', $contents ) ) { // Do not base64-encode non-binary files (sane SVGs). // (This often produces longer URLs, but they compress better, yielding a net smaller size.) $uri = 'data:' . $type . ',' . rawurlencode( $contents ); if ( !$ie8Compat || strlen( $uri ) < self::DATA_URI_SIZE_LIMIT ) { return $uri; } } // Try #2: Encoded data URI $uri = 'data:' . $type . ';base64,' . base64_encode( $contents ); if ( !$ie8Compat || strlen( $uri ) < self::DATA_URI_SIZE_LIMIT ) { return $uri; } // A data URI couldn't be produced return false; } /** * @param $file string * @return bool|string */ public static function getMimeType( $file ) { $realpath = realpath( $file ); if ( $realpath && function_exists( 'finfo_file' ) && function_exists( 'finfo_open' ) && defined( 'FILEINFO_MIME_TYPE' ) ) { return finfo_file( finfo_open( FILEINFO_MIME_TYPE ), $realpath ); } // Infer the MIME-type from the file extension $ext = strtolower( pathinfo( $file, PATHINFO_EXTENSION ) ); if ( isset( self::$mimeTypes[$ext] ) ) { return self::$mimeTypes[$ext]; } return false; } /** * Build a CSS 'url()' value for the given URL, quoting parentheses (and other funny characters) * and escaping quotes as necessary. * * See http://www.w3.org/TR/css-syntax-3/#consume-a-url-token * * @param string $url URL to process * @return string 'url()' value, usually just `"url($url)"`, quoted/escaped if necessary */ public static function buildUrlValue( $url ) { // The list below has been crafted to match URLs such as: // scheme://user@domain:port/~user/fi%20le.png?query=yes&really=y+s // data:image/png;base64,R0lGODlh/+== if ( preg_match( '!^[\w\d:@/~.%+;,?&=-]+$!', $url ) ) { return "url($url)"; } else { return 'url("' . strtr( $url, array( '\\' => '\\\\', '"' => '\\"' ) ) . '")'; } } /** * Remaps CSS URL paths and automatically embeds data URIs for CSS rules * or url() values preceded by an / * @embed * / comment. * * @param string $source CSS data to remap * @param string $local File path where the source was read from * @param string $remote URL path to the file * @param bool $embedData If false, never do any data URI embedding, * even if / * @embed * / is found. * @return string Remapped CSS data */ public static function remap( $source, $local, $remote, $embedData = true ) { // High-level overview: // * For each CSS rule in $source that includes at least one url() value: // * Check for an @embed comment at the start indicating that all URIs should be embedded // * For each url() value: // * Check for an @embed comment directly preceding the value // * If either @embed comment exists: // * Embedding the URL as data: URI, if it's possible / allowed // * Otherwise remap the URL to work in generated stylesheets // Guard against trailing slashes, because "some/remote/../foo.png" // resolves to "some/remote/foo.png" on (some?) clients (bug 27052). if ( substr( $remote, -1 ) == '/' ) { $remote = substr( $remote, 0, -1 ); } // Disallow U+007F DELETE, which is illegal anyway, and which // we use for comment placeholders. $source = str_replace( "\x7f", "?", $source ); // Replace all comments by a placeholder so they will not interfere with the remapping. // Warning: This will also catch on anything looking like the start of a comment between // quotation marks (e.g. "foo /* bar"). $comments = array(); $pattern = '/(?!' . CSSMin::EMBED_REGEX . ')(' . CSSMin::COMMENT_REGEX . ')/s'; $source = preg_replace_callback( $pattern, function ( $match ) use ( &$comments ) { $comments[] = $match[ 0 ]; return CSSMin::PLACEHOLDER . ( count( $comments ) - 1 ) . 'x'; }, $source ); // Note: This will not correctly handle cases where ';', '{' or '}' // appears in the rule itself, e.g. in a quoted string. You are advised // not to use such characters in file names. We also match start/end of // the string to be consistent in edge-cases ('@import url(…)'). $pattern = '/(?:^|[;{])\K[^;{}]*' . CSSMin::URL_REGEX . '[^;}]*(?=[;}]|$)/'; $source = preg_replace_callback( $pattern, function ( $matchOuter ) use ( $local, $remote, $embedData ) { $rule = $matchOuter[0]; // Check for global @embed comment and remove it. Allow other comments to be present // before @embed (they have been replaced with placeholders at this point). $embedAll = false; $rule = preg_replace( '/^((?:\s+|' . CSSMin::PLACEHOLDER . '(\d+)x)*)' . CSSMin::EMBED_REGEX . '\s*/', '$1', $rule, 1, $embedAll ); // Build two versions of current rule: with remapped URLs // and with embedded data: URIs (where possible). $pattern = '/(?P' . CSSMin::EMBED_REGEX . '\s*|)' . CSSMin::URL_REGEX . '/'; $ruleWithRemapped = preg_replace_callback( $pattern, function ( $match ) use ( $local, $remote ) { $remapped = CSSMin::remapOne( $match['file'], $match['query'], $local, $remote, false ); return CSSMin::buildUrlValue( $remapped ); }, $rule ); if ( $embedData ) { // Remember the occurring MIME types to avoid fallbacks when embedding some files. $mimeTypes = array(); $ruleWithEmbedded = preg_replace_callback( $pattern, function ( $match ) use ( $embedAll, $local, $remote, &$mimeTypes ) { $embed = $embedAll || $match['embed']; $embedded = CSSMin::remapOne( $match['file'], $match['query'], $local, $remote, $embed ); $url = $match['file'] . $match['query']; $file = $local . $match['file']; if ( !CSSMin::isRemoteUrl( $url ) && !CSSMin::isLocalUrl( $url ) && file_exists( $file ) ) { $mimeTypes[ CSSMin::getMimeType( $file ) ] = true; } return CSSMin::buildUrlValue( $embedded ); }, $rule ); // Are all referenced images SVGs? $needsEmbedFallback = $mimeTypes !== array( 'image/svg+xml' => true ); } if ( !$embedData || $ruleWithEmbedded === $ruleWithRemapped ) { // We're not embedding anything, or we tried to but the file is not embeddable return $ruleWithRemapped; } elseif ( $embedData && $needsEmbedFallback ) { // Build 2 CSS properties; one which uses a data URI in place of the @embed comment, and // the other with a remapped and versioned URL with an Internet Explorer 6 and 7 hack // making it ignored in all browsers that support data URIs return "$ruleWithEmbedded;$ruleWithRemapped!ie"; } else { // Look ma, no fallbacks! This is for files which IE 6 and 7 don't support anyway: SVG. return $ruleWithEmbedded; } }, $source ); // Re-insert comments $pattern = '/' . CSSMin::PLACEHOLDER . '(\d+)x/'; $source = preg_replace_callback( $pattern, function( $match ) use ( &$comments ) { return $comments[ $match[1] ]; }, $source ); return $source; } /** * Is this CSS rule referencing a remote URL? * * @private Until we require PHP 5.5 and we can access self:: from closures. * @param string $maybeUrl * @return bool */ public static function isRemoteUrl( $maybeUrl ) { if ( substr( $maybeUrl, 0, 2 ) === '//' || parse_url( $maybeUrl, PHP_URL_SCHEME ) ) { return true; } return false; } /** * Is this CSS rule referencing a local URL? * * @private Until we require PHP 5.5 and we can access self:: from closures. * @param string $maybeUrl * @return bool */ public static function isLocalUrl( $maybeUrl ) { if ( $maybeUrl !== '' && $maybeUrl[0] === '/' && !self::isRemoteUrl( $maybeUrl ) ) { return true; } return false; } /** * Remap or embed a CSS URL path. * * @param string $file URL to remap/embed * @param string $query * @param string $local File path where the source was read from * @param string $remote URL path to the file * @param bool $embed Whether to do any data URI embedding * @return string Remapped/embedded URL data */ public static function remapOne( $file, $query, $local, $remote, $embed ) { // The full URL possibly with query, as passed to the 'url()' value in CSS $url = $file . $query; // Expand local URLs with absolute paths like /w/index.php to possibly protocol-relative URL, if // wfExpandUrl() is available. (This will not be the case if we're running outside of MW.) if ( self::isLocalUrl( $url ) && function_exists( 'wfExpandUrl' ) ) { return wfExpandUrl( $url, PROTO_RELATIVE ); } // Pass thru fully-qualified and protocol-relative URLs and data URIs, as well as local URLs if // we can't expand them. if ( self::isRemoteUrl( $url ) || self::isLocalUrl( $url ) ) { return $url; } if ( $local === false ) { // Assume that all paths are relative to $remote, and make them absolute $url = $remote . '/' . $url; } else { // We drop the query part here and instead make the path relative to $remote $url = "{$remote}/{$file}"; // Path to the actual file on the filesystem $localFile = "{$local}/{$file}"; if ( file_exists( $localFile ) ) { // Add version parameter as the first five hex digits // of the MD5 hash of the file's contents. $url .= '?' . substr( md5_file( $localFile ), 0, 5 ); if ( $embed ) { $data = self::encodeImageAsDataURI( $localFile ); if ( $data !== false ) { return $data; } } } // If any of these conditions failed (file missing, we don't want to embed it // or it's not embeddable), return the URL (possibly with ?timestamp part) } if ( function_exists( 'wfRemoveDotSegments' ) ) { $url = wfRemoveDotSegments( $url ); } return $url; } /** * Removes whitespace from CSS data * * @param string $css CSS data to minify * @return string Minified CSS data */ public static function minify( $css ) { return trim( str_replace( array( '; ', ': ', ' {', '{ ', ', ', '} ', ';}' ), array( ';', ':', '{', '{', ',', '}', '}' ), preg_replace( array( '/\s+/', '/\/\*.*?\*\//s' ), array( ' ', '' ), $css ) ) ); } }