Prevent long strings from causing a regexp buffer overflow exception.

This bug was reported here: sass#104

doc-src/SASS_CHANGELOG.md

@@ -15,6 +15,8 @@
   been successfully compiled. Thanks to [Christian Peters](https://github.com/ChristianPeters).
 * Allow absolute paths to be used in an importer with a different root.
 * Don't destructively modify the options when running `Sass::Plugin.force_update`.
+* Prevent Regexp buffer overflows when parsing long strings.
+  Thanks to [Agworld](https://github.com/Agworld).
 
 ### Deprecations -- Must Read!
 

lib/sass/scss/parser.rb

@@ -437,7 +437,7 @@ def declaration_or_ruleset
       end
 
       def selector_sequence
-        if sel = tok(STATIC_SELECTOR)
+        if sel = tok(STATIC_SELECTOR, true)
           return [sel]
         end
 
@@ -681,7 +681,7 @@ def value!
         # we don't parse it at all, and instead return a plain old string
         # containing the value.
         # This results in a dramatic speed increase.
-        if val = tok(STATIC_VALUE)
+        if val = tok(STATIC_VALUE, true)
           return space, Sass::Script::String.new(val.strip)
         end
         return space, sass_script(:parse)
@@ -770,7 +770,7 @@ def _interp_string(type)
       end
 
       def interp_ident(start = IDENT)
-        return unless val = tok(start) || interpolation || tok(IDENT_HYPHEN_INTERP)
+        return unless val = tok(start) || interpolation || tok(IDENT_HYPHEN_INTERP, true)
         res = [val]
         while val = tok(NAME) || interpolation
           res << val
@@ -944,9 +944,14 @@ def self.prior_snippet(scanner)
       # This is important because `#tok` is called all the time.
       NEWLINE = "\n"
 
-      def tok(rx)
+      def tok(rx, last_group_lookahead = false)
         res = @scanner.scan(rx)
         if res
+          if last_group_lookahead
+            last_group = @scanner[-1]
+            @scanner.pos -= last_group.length
+            res.chomp!(last_group)
+          end
           @line += res.count(NEWLINE)
           @expected = nil
           if !@strs.empty? && rx != COMMENT && rx != SINGLE_LINE_COMMENT

lib/sass/scss/rx.rb

@@ -112,17 +112,17 @@ def self.quote(str, flags = 0)
       INTERP_START = /#\{/
       MOZ_ANY = quote(":-moz-any(", Regexp::IGNORECASE)
 
-      IDENT_HYPHEN_INTERP = /-(?=#\{)/
+      IDENT_HYPHEN_INTERP = /-(#\{)/
       STRING1_NOINTERP = /\"((?:[^\n\r\f\\"#]|#(?!\{)|\\#{NL}|#{ESCAPE})*)\"/
       STRING2_NOINTERP = /\'((?:[^\n\r\f\\'#]|#(?!\{)|\\#{NL}|#{ESCAPE})*)\'/
       STRING_NOINTERP = /#{STRING1_NOINTERP}|#{STRING2_NOINTERP}/
       # Can't use IDENT here, because it seems to take exponential time on 1.8.
       # We could use it for 1.9 only, but I don't want to introduce a cross-version
       # behavior difference.
       # In any case, almost all CSS idents will be matched by this.
-      STATIC_VALUE = /(-?#{NMSTART}|#{STRING_NOINTERP}|\s(?!%)|#[a-f0-9]|[,%]|#{NUM}|\!important)+(?=[;}])/i
+      STATIC_VALUE = /(-?#{NMSTART}|#{STRING_NOINTERP}|\s(?!%)|#[a-f0-9]|[,%]|#{NUM}|\!important)+([;}])/i
 
-      STATIC_SELECTOR = /(#{NMCHAR}|\s|[,>+*]|[:#.]#{NMSTART})+(?=[{])/i
+      STATIC_SELECTOR = /(#{NMCHAR}|\s|[,>+*]|[:#.]#{NMSTART})+([{])/i
     end
   end
 end