Fix render length resource limit so it doesn't multiply nested output

lib/liquid/block_body.rb

@@ -155,12 +155,10 @@ module Liquid
     end
 
     def render_to_output_buffer(context, output)
-      context.resource_limits.render_score += @nodelist.length
+      context.resource_limits.increment_render_score(@nodelist.length)
 
       idx = 0
       while (node = @nodelist[idx])
-        previous_output_size = output.bytesize
-
         if node.instance_of?(String)
           output << node
         else
@@ -172,7 +170,7 @@ module Liquid
         end
         idx += 1
 
-        raise_if_resource_limits_reached(context, output.bytesize - previous_output_size)
+        context.resource_limits.check_render_length(output.bytesize)
       end
 
       output
@@ -184,17 +182,13 @@ module Liquid
       node.render_to_output_buffer(context, output)
     rescue UndefinedVariable, UndefinedDropMethod, UndefinedFilter => e
       context.handle_error(e, node.line_number)
+    rescue MemoryError
+      raise
     rescue ::StandardError => e
       line_number = node.is_a?(String) ? nil : node.line_number
       output << context.handle_error(e, line_number)
     end
 
-    def raise_if_resource_limits_reached(context, length)
-      context.resource_limits.render_length += length
-      return unless context.resource_limits.reached?
-      raise MemoryError, "Memory limits exceeded"
-    end
-
     def create_variable(token, parse_context)
       token.scan(ContentOfVariable) do |content|
         markup = content.first

lib/liquid/resource_limits.rb

@@ -2,8 +2,8 @@
 
 module Liquid
   class ResourceLimits
-    attr_accessor :render_length, :render_score, :assign_score,
-      :render_length_limit, :render_score_limit, :assign_score_limit
+    attr_accessor :render_length_limit, :render_score_limit, :assign_score_limit
+    attr_reader :render_score, :assign_score
 
     def initialize(limits)
       @render_length_limit = limits[:render_length_limit]
@@ -12,14 +12,32 @@ module Liquid
       reset
     end
 
+    def increment_render_score(amount)
+      @render_score += amount
+      raise_limits_reached if @render_score_limit && @render_score > @render_score_limit
+    end
+
+    def increment_assign_score(amount)
+      @assign_score += amount
+      raise_limits_reached if @assign_score_limit && @assign_score > @assign_score_limit
+    end
+
+    def check_render_length(output_byte_size)
+      raise_limits_reached if @render_length_limit && output_byte_size > @render_length_limit
+    end
+
+    def raise_limits_reached
+      @reached_limit = true
+      raise MemoryError, "Memory limits exceeded"
+    end
+
     def reached?
-      (@render_length_limit && @render_length > @render_length_limit) ||
-        (@render_score_limit && @render_score > @render_score_limit) ||
-        (@assign_score_limit && @assign_score > @assign_score_limit)
+      @reached_limit
     end
 
     def reset
-      @render_length = @render_score = @assign_score = 0
+      @reached_limit = false
+      @render_score = @assign_score = 0
     end
   end
 end

lib/liquid/tags/assign.rb

@@ -27,7 +27,7 @@ module Liquid
     def render_to_output_buffer(context, output)
       val = @from.render(context)
       context.scopes.last[@to] = val
-      context.resource_limits.assign_score += assign_score_of(val)
+      context.resource_limits.increment_assign_score(assign_score_of(val))
       output
     end
 

lib/liquid/tags/capture.rb

@@ -27,7 +27,7 @@ module Liquid
     def render_to_output_buffer(context, output)
       capture_output = render(context)
       context.scopes.last[@to] = capture_output
-      context.resource_limits.assign_score += capture_output.bytesize
+      context.resource_limits.increment_assign_score(capture_output.bytesize)
       output
     end