Force UTF-8 encoding on task results

Since task results are stored as binary blobs, they can be set as
strings in whatever encoding you like. This can create problems for
the API, which blindly tries to convert all attributes to JSON - any
value containing ASCII with ansi escape codes will fail with a
conversion error.

It seems reasonable to expect that all string values should be encoded
as UTF-8 - the alternative is for the API to have to force the
encoding on every single string that comes its way.

This change forces incoming values to be converted to UTF-8 prior to
being stored. It will also convert outgoing values in the case that
they have already been persisted prior to this change - though this
extra check I'm sure could eventually be removed.

Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1557731

app/models/miq_task.rb

@@ -233,12 +233,14 @@ def task_results
       serializer_name = binary_blob.data_type
       serializer_name = "Marshal" unless serializer_name == "YAML" # YAML or Marshal, for now
       serializer = serializer_name.constantize
-      return serializer.load(binary_blob.binary)
+      result = serializer.load(binary_blob.binary)
+      return result.kind_of?(String) ? result.force_encoding("UTF-8") : result
     end
     nil
   end
 
   def task_results=(value)
+    value = value.force_encoding("UTF-8") if value.kind_of?(String)
     self.binary_blob   = BinaryBlob.new(:name => "task_results", :data_type => "YAML")
     binary_blob.binary = YAML.dump(value)
   end

spec/models/miq_task_spec.rb

@@ -485,6 +485,29 @@
     end
   end
 
+  describe "#task_results" do
+    it "forces UTF-8 encoding" do
+      task = FactoryGirl.create(
+        :miq_task,
+        :binary_blob => BinaryBlob.new(
+          :name      => "task_results",
+          :data_type => "YAML",
+          :binary    => YAML.dump("\xC3\xA4".force_encoding("ASCII-8BIT"))
+        )
+      )
+
+      expect(task.task_results).to eq("ä")
+    end
+  end
+
+  describe "#task_results=" do
+    it "forces UTF-8 encoding" do
+      task = FactoryGirl.create(:miq_task, :task_results => "\xC3\xA4".force_encoding("ASCII-8BIT"))
+
+      expect(task.task_results).to eq("ä")
+    end
+  end
+
   private
 
   def create_test_task(name, status, updated)