JavaScriptDistiller fixes:

* Removed some repeated subexpressions, /(.)*/ etc. These cause the stack space to be rapidly exhausted, leading to a segfault for malicious input. I replaced the ([\r\n]|.) subexpressions with a dot with a /s modifier. Added a pcre.recursion_limit hack to take care of the rest.
* Supported assertions and non-capturing subpatterns in ParseMaster::add() by recognising that parentheses that aren't followed by "?" are capturing. Used another assertion to do this.
* Fixed a bug whereby if a single-line comment had a slash in it, it was recognised as a regex instead of a comment. This occurred because the leading whitespace caused the regex regex to match at an earlier string position than the comment regex, giving it undue precedence. This was the subject of several reports on IRC and the main reason for me starting work on JavaScriptDistiller. Used a lookbehind assertion.
* Give comments precedence over regexes and strings where there is ambiguity at the same string location. Not sure if this does anything, but it seemed like a good idea at the time.
* Removed unused variable ParseMaster::$TRIM.
* To test it, I ran the old and new jquery.js output through Google Closure Compiler. The result was the same, proving that there are no functional differences.

diff --git a/includes/libs/JavaScriptDistiller.php b/includes/libs/JavaScriptDistiller.php
index 32816b2..123d802 100644 (file)
--- a/includes/libs/JavaScriptDistiller.php
+++ b/includes/libs/JavaScriptDistiller.php
@@ -19,12 +19,20 @@ class JavaScriptDistiller {
         * @param $stripVerticalSpace Boolean: Try to remove as much vertical whitespace as possible
         */
        public static function stripWhiteSpace( $script, $stripVerticalSpace = false ) {
+               // Try to avoid segfaulting
+               // I saw segfaults with a limit of 10000, 1000 seems to work
+               $oldLimit = ini_get( 'pcre.recursion_limit' );
+               if ( intval( $oldLimit ) > 1000 ) {
+                       ini_set( 'pcre.recursion_limit', '1000' );
+               }
+
                $script = self::stripHorizontalSpace( $script );
                // If requested, make some vertical whitespace collapsing as well
                if ( $stripVerticalSpace ) {
                        $script = self::stripVerticalSpace( $script );
                }
                // Done
+               ini_set( 'pcre.recursion_limit', $oldLimit );
                return $script;
        }
 
@@ -74,55 +82,44 @@ class JavaScriptDistiller {
                // to \s if we use a backslash as the escape character. We work around this by using an
                // obscure escape character that we hope will never appear at the end of a line.
                $parser->escapeChar = chr( 1 );
+               
+               // C-style comment: use non-greedy repetition to find the end
+               $parser->add( '\/ \* .*? \* \/' );
+
+               // Preserve the newline after a C++-style comment -- bug 27046
+               $parser->add( '\/ \/ [^\r\n]* ( [\r\n] )', '$2' );
+
                // Protect strings. The original code had [^\'\\v] here, but that didn't armor multiline
                // strings correctly. This also armors multiline strings that don't have backslashes at the
                // end of the line (these are invalid), but that's fine because we're just armoring here.
 
                // Single quotes
-               $parser->add( 
-                       '\' (' . // start quote
+               $parser->add(
+                       '\'' . // start quote
                        '[^\'\\\\]*' . // a run of non-special characters
-                       '(' .
-                               '\\\\ ( . | [\r\n] )' . // a backslash followed by a character or line ending
+                       '(?:' .
+                               '\\\\ .' . // a backslash followed by a character or line ending
                                '[^\'\\\\]*' . // a run of non-special characters
                        ')*' . // any number of the above
-                       ') \'', // end quote
+                       '\'', // end quote
                        '$1' );
 
                // Double quotes: same as above
-               $parser->add( '" ( [^"\\\\]* ( \\\\ ( . | [\r\n] ) [^"\\\\]* )* ) "', '$1' );
+               $parser->add( '" [^"\\\\]* (?: \\\\ . [^"\\\\]* )* "', '$1' );
 
                // Protect regular expressions
                // Regular expression with whitespace before it
                $parser->add(
-                       '[ \t]+ ( ( \/' . // whitespace then start slash
+                       '(?<= [ \t] | [^\w\$\/\'"*)\?:] )' . // assert that whitespace or punctuation precedes
+                       '\/' . // start slash
                        '[^\r\n\*]' . // not a comment-start or line ending
                        '[^\/\r\n\\\\]*' . // a sequence of non-special characters
-                       '(' . 
+                       '(?:' . 
                                '\\\\.' . // an escaped dot
                                '[^\/\r\n\\\\]*' . // a sequence of non-special characters
                        ')*' . // any number of the above
-                       '\/(i|g)*' . // pattern end, optional modifier
-                       ') )', 
+                       '\/[ig]*' , // pattern end, optional modifier
                        '$1' );
-               // Regular expression with an operator before it
-               $parser->add( 
-                       '( [^\w\$\/\'"*)\?:] (\/' . // certain kinds of punctuation and then start slash
-                       '[^\r\n\*]' . // not a comment-start or line ending
-                       '[^\/\r\n\\\\]*' . // a sequence of non-special characters
-                       '(' . 
-                               '\\\\.' . // an escaped dot
-                               '[^\/\r\n\\\\]*' . // a sequence of non-special characters
-                       ')*' . // any number of the above
-                       '\/(i|g)*)' . // pattern end, optional modifier
-                       ')',
-                       '$1' );
-
-               // C-style comment: use non-greedy repetition to find the end
-               $parser->add( '\/ \* ( . | [\r\n] )*? \* \/' );
-
-               // Preserve the newline after a C++-style comment -- bug 27046
-               $parser->add( '\/ \/ [^\r\n]* ( [\r\n] )', '$2' );
                return $parser;
        }
 }
@@ -149,10 +146,9 @@ class ParseMaster {
        const LENGTH = 2;
 
        // used to determine nesting levels
-       private $GROUPS = '/\(/';//g
+       private $GROUPS = '/\( (?! \? ) /x';//g
        private $SUB_REPLACE = '/\$\d/';
        private $INDEXED = '/^\$\d+$/';
-       //private $TRIM = '/([\'"])\1\.(.*)\.\1\1$/';
        private $ESCAPE = '/\\\./';//g
        private $QUOTE = '/\'/';
        private $DELETED = '/\x01[^\x01]*\x01/';//g
@@ -197,9 +193,9 @@ class ParseMaster {
                // simulate the _patterns.toSTring of Dean
                $regexp = '/';
                foreach ($this->_patterns as $reg) {
-                       $regexp .= '(' . $reg[self::EXPRESSION] . ')|';
+                       $regexp .= '(' . $reg[self::EXPRESSION] . ")|\n";
                }
-               $regexp = substr($regexp, 0, -1) . '/Sx';
+               $regexp = substr($regexp, 0, -2) . '/Sxs';
                $regexp .= ($this->ignoreCase) ? 'i' : '';
 
                $string = $this->_escape($string, $this->escapeChar);