Add add_limit_offset! to adapters.

activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb

@@ -181,6 +181,29 @@ module ActiveRecord
       # done if the transaction block raises an exception or returns false.
       def rollback_db_transaction() end
 
+      # Appends +LIMIT+ and +OFFSET+ options to an SQL statement, or some SQL
+      # fragment that has the same semantics as LIMIT and OFFSET.
+      #
+      # +options+ must be a Hash which contains a +:limit+ option
+      # and an +:offset+ option.
+      #
+      # This method *modifies* the +sql+ parameter.
+      #
+      # ===== Examples
+      #  add_limit_offset!('SELECT * FROM suppliers', {:limit => 10, :offset => 50})
+      # generates
+      #  SELECT * FROM suppliers LIMIT 10 OFFSET 50
+
+      def add_limit_offset!(sql, options)
+        if limit = options[:limit]
+          sql << " LIMIT #{sanitize_limit(limit)}"
+        end
+        if offset = options[:offset]
+          sql << " OFFSET #{offset.to_i}"
+        end
+        sql
+      end
+
       def default_sequence_name(table, column)
         nil
       end

activerecord/lib/active_record/connection_adapters/mysql_adapter.rb

@@ -375,6 +375,18 @@ module ActiveRecord
         execute("RELEASE SAVEPOINT #{current_savepoint_name}")
       end
 
+      def add_limit_offset!(sql, options) #:nodoc:
+        limit, offset = options[:limit], options[:offset]
+        if limit && offset
+          sql << " LIMIT #{offset.to_i}, #{sanitize_limit(limit)}"
+        elsif limit
+          sql << " LIMIT #{sanitize_limit(limit)}"
+        elsif offset
+          sql << " OFFSET #{offset.to_i}"
+        end
+        sql
+      end
+
       # SCHEMA STATEMENTS ========================================
 
       def structure_dump #:nodoc:

activerecord/test/cases/adapter_test.rb

@@ -142,4 +142,25 @@ class AdapterTest < ActiveRecord::TestCase
       end
     end
   end
+
+  def test_add_limit_offset_should_sanitize_sql_injection_for_limit_without_comas
+    sql_inject = "1 select * from schema"
+      assert_equal " LIMIT 1", @connection.add_limit_offset!("", :limit => sql_inject)
+    if current_adapter?(:MysqlAdapter)
+      assert_equal " LIMIT 7, 1", @connection.add_limit_offset!("", :limit => sql_inject, :offset => 7)
+    else
+      assert_equal " LIMIT 1 OFFSET 7", @connection.add_limit_offset!("", :limit => sql_inject, :offset => 7)
+    end
+  end
+
+  def test_add_limit_offset_should_sanitize_sql_injection_for_limit_with_comas
+    sql_inject = "1, 7 procedure help()"
+    if current_adapter?(:MysqlAdapter)
+      assert_equal " LIMIT 1,7", @connection.add_limit_offset!("", :limit => sql_inject)
+      assert_equal " LIMIT 7, 1", @connection.add_limit_offset!("", :limit => '1 ; DROP TABLE USERS', :offset => 7)
+    else
+      assert_equal " LIMIT 1,7", @connection.add_limit_offset!("", :limit => sql_inject)
+      assert_equal " LIMIT 1,7 OFFSET 7", @connection.add_limit_offset!("", :limit => sql_inject, :offset => 7)
+    end
+  end
 end