From 1fba5bc73613164a3d43892e6f7f9b721d91440b Mon Sep 17 00:00:00 2001
From: Masahiro Nakagawa <repeatedly@gmail.com>
Date: Mon, 22 Aug 2016 08:56:55 +0900
Subject: [PATCH] Merge pull request #1176 from
 sonots/prevent_overwriting_reserved_placeholders

Fix to prevent overwriting reserved placeholder keys such as tag
---
 .../plugin/filter_record_transformer.rb       |  4 +++-
 test/plugin/test_filter_record_transformer.rb | 22 +++++++++++++++----
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/lib/fluent/plugin/filter_record_transformer.rb b/lib/fluent/plugin/filter_record_transformer.rb
index d86664294c..9396e38ad9 100644
--- a/lib/fluent/plugin/filter_record_transformer.rb
+++ b/lib/fluent/plugin/filter_record_transformer.rb
@@ -204,7 +204,9 @@ def prepare_placeholders(placeholder_values)
             end
           elsif value.kind_of?(Hash) # record, etc
             value.each do |k, v|
-              placeholders.store("${#{k}}", v) # foo
+              unless placeholder_values.has_key?(k) # prevent overwriting reserved keys such as tag
+                placeholders.store("${#{k}}", v) # foo
+              end
               placeholders.store(%Q[${#{key}["#{k}"]}], v) # record["foo"]
             end
           else # string, interger, float, and others?
diff --git a/test/plugin/test_filter_record_transformer.rb b/test/plugin/test_filter_record_transformer.rb
index 8b94cf7eba..1a4a66659d 100644
--- a/test/plugin/test_filter_record_transformer.rb
+++ b/test/plugin/test_filter_record_transformer.rb
@@ -172,10 +172,7 @@ def emit(config, msgs = [''])
       yield d if block_given?
       d.run {
         msgs.each do |msg|
-          record = {
-            'eventType0' => 'bar',
-            'message'    => msg,
-          }
+          record = {'eventType0' => 'bar', 'message' => msg}
           record = record.merge(msg) if msg.is_a?(Hash)
           d.emit(record, @time)
         end
@@ -269,6 +266,23 @@ def emit(config, msgs = [''])
         end
       end
 
+      test "Prevent overwriting reserved keys such as tag with enable_ruby #{enable_ruby}" do
+        config = %[
+          enable_ruby #{enable_ruby}
+          <record>
+            new_tag ${tag}
+            new_record_tag ${record["tag"]}
+          </record>
+        ]
+        records = [{'tag' => 'tag', 'time' => 'time'}]
+        filtered = filter(config, records)
+        filtered.each_with_index do |(_t, r), i|
+          assert_not_equal('tag', r['new_tag'])
+          assert_equal(@tag, r['new_tag'])
+          assert_equal('tag', r['new_record_tag'])
+        end
+      end
+
       test "hash values with placeholders with enable_ruby #{enable_ruby}" do
         config = %[
           enable_ruby #{enable_ruby}