Serializer: reraise all .load errors as UnmarshalError (petergoldstein#1011)

* Serializer: for Marshal, catch all .load errors

In order to avoid missing an error message to filter out, treat any Marshal.load error as a
failed serialization, and trust Ruby's e.cause system to provide a
lineage of the error's true beginning.

* Treat all deserialization errors as UnmarshalError

Author: olleolleolle

lib/dalli/protocol/value_serializer.rb

@@ -33,42 +33,17 @@ def store(value, req_options, bitflags)
         [store_value, bitflags]
       end
 
-      # TODO: Some of these error messages need to be validated.  It's not obvious
-      # that all of them are actually generated by the invoked code
-      # in current systems
-      # rubocop:disable Layout/LineLength
-      TYPE_ERR_REGEXP = %r{needs to have method `_load'|exception class/object expected|instance of IO needed|incompatible marshal file format}.freeze
-      ARGUMENT_ERR_REGEXP = /undefined class|marshal data too short/.freeze
-      NAME_ERR_STR = 'uninitialized constant'
-      # rubocop:enable Layout/LineLength
-
       def retrieve(value, bitflags)
         serialized = (bitflags & FLAG_SERIALIZED) != 0
-        serialized ? serializer.load(value) : value
-      rescue TypeError => e
-        filter_type_error(e)
-      rescue ArgumentError => e
-        filter_argument_error(e)
-      rescue NameError => e
-        filter_name_error(e)
-      end
-
-      def filter_type_error(err)
-        raise err unless TYPE_ERR_REGEXP.match?(err.message)
-
-        raise UnmarshalError, "Unable to unmarshal value: #{err.message}"
-      end
-
-      def filter_argument_error(err)
-        raise err unless ARGUMENT_ERR_REGEXP.match?(err.message)
-
-        raise UnmarshalError, "Unable to unmarshal value: #{err.message}"
-      end
-
-      def filter_name_error(err)
-        raise err unless err.message.include?(NAME_ERR_STR)
-
-        raise UnmarshalError, "Unable to unmarshal value: #{err.message}"
+        if serialized
+          begin
+            serializer.load(value)
+          rescue StandardError
+            raise UnmarshalError, 'Unable to unmarshal value'
+          end
+        else
+          value
+        end
       end
 
       def serializer

test/protocol/test_value_serializer.rb

@@ -181,7 +181,7 @@
           end
         end
 
-        assert_equal exception.message, "Unable to unmarshal value: #{error_message}"
+        assert_equal exception.cause.message, error_message
       end
     end
 
@@ -198,7 +198,7 @@
           end
         end
 
-        assert_equal exception.message, "Unable to unmarshal value: #{error_message}"
+        assert_equal exception.cause.message, error_message
       end
     end
 
@@ -212,7 +212,7 @@
           vs.retrieve(raw_value, Dalli::Protocol::ValueSerializer::FLAG_SERIALIZED)
         end
 
-        assert_equal exception.message, "Unable to unmarshal value: #{error_message}"
+        assert_equal exception.cause.message, error_message
       end
     end
 
@@ -226,23 +226,7 @@
           vs.retrieve(raw_value, Dalli::Protocol::ValueSerializer::FLAG_SERIALIZED)
         end
 
-        assert exception.message.start_with?("Unable to unmarshal value: #{error_message}")
-      end
-    end
-
-    describe 'when deserialization raises a TypeError with a non-matching message' do
-      let(:error_message) { SecureRandom.hex(10) }
-      let(:serializer) { Marshal }
-
-      it 're-raises TypeError' do
-        error = ->(_arg) { raise TypeError, error_message }
-        exception = serializer.stub :load, error do
-          assert_raises TypeError do
-            vs.retrieve(raw_value, Dalli::Protocol::ValueSerializer::FLAG_SERIALIZED)
-          end
-        end
-
-        assert_equal error_message, exception.message
+        assert exception.cause.message.start_with?(error_message)
       end
     end
 
@@ -259,23 +243,7 @@
           end
         end
 
-        assert exception.message.start_with?("Unable to unmarshal value: #{error_message}")
-      end
-    end
-
-    describe 'when deserialization raises a NameError with a non-matching message' do
-      let(:error_message) { SecureRandom.hex(10) }
-      let(:serializer) { Marshal }
-
-      it 're-raises NameError' do
-        error = ->(_arg) { raise NameError, error_message }
-        exception = serializer.stub :load, error do
-          assert_raises NameError do
-            vs.retrieve(raw_value, Dalli::Protocol::ValueSerializer::FLAG_SERIALIZED)
-          end
-        end
-
-        assert exception.message.start_with?(error_message)
+        assert exception.cause.message.start_with?(error_message)
       end
     end
 
@@ -289,7 +257,7 @@
           vs.retrieve(raw_value, Dalli::Protocol::ValueSerializer::FLAG_SERIALIZED)
         end
 
-        assert_equal exception.message, "Unable to unmarshal value: #{error_message}"
+        assert_equal exception.cause.message, error_message
       end
     end
 
@@ -303,23 +271,7 @@
           vs.retrieve(raw_value, Dalli::Protocol::ValueSerializer::FLAG_SERIALIZED)
         end
 
-        assert_equal exception.message, "Unable to unmarshal value: #{error_message}"
-      end
-    end
-
-    describe 'when deserialization raises an ArgumentError with a non-matching message' do
-      let(:error_message) { SecureRandom.hex(10) }
-      let(:serializer) { Marshal }
-
-      it 're-raises ArgumentError' do
-        error = ->(_arg) { raise ArgumentError, error_message }
-        exception = serializer.stub :load, error do
-          assert_raises ArgumentError do
-            vs.retrieve(raw_value, Dalli::Protocol::ValueSerializer::FLAG_SERIALIZED)
-          end
-        end
-
-        assert_equal exception.message, error_message
+        assert_equal exception.cause.message, error_message
       end
     end
 
@@ -334,7 +286,7 @@
                      deserialized_value
       end
 
-      it 'raises UnmarshalError for non-seriaized data' do
+      it 'raises UnmarshalError for non-serialized data' do
         assert_raises Dalli::UnmarshalError do
           vs.retrieve(:not_serialized_value, Dalli::Protocol::ValueSerializer::FLAG_SERIALIZED)
         end