Merge pull request #38905 from juanvallejo/jvallejo/return-typed-json-yaml-syntax-errs

Automatic merge from submit-queue (batch tested with PRs 38905, 40421)

return typed json,yaml syntax errors

**Release note**:
```release-note
release-note-none
```

This patch creates error types for JSON and YAML syntax errors to make
it easier to handle these types of errors by callers of JSON and YAML
decoders.

@fabianofranz @AdoHe

staging/src/k8s.io/apimachinery/pkg/util/yaml/decoder.go

@@ -69,11 +69,10 @@ func (d *YAMLToJSONDecoder) Decode(into interface{}) error {
 	}
 
 	if len(bytes) != 0 {
-		data, err := yaml.YAMLToJSON(bytes)
+		err := yaml.Unmarshal(bytes, into)
 		if err != nil {
-			return err
+			return YAMLSyntaxError{err}
 		}
-		return json.Unmarshal(data, into)
 	}
 	return err
 }
@@ -184,6 +183,23 @@ type YAMLOrJSONDecoder struct {
 	rawData []byte
 }
 
+type JSONSyntaxError struct {
+	Line int
+	Err  error
+}
+
+func (e JSONSyntaxError) Error() string {
+	return fmt.Sprintf("json: line %d: %s", e.Line, e.Err.Error())
+}
+
+type YAMLSyntaxError struct {
+	err error
+}
+
+func (e YAMLSyntaxError) Error() string {
+	return e.err.Error()
+}
+
 // NewYAMLOrJSONDecoder returns a decoder that will process YAML documents
 // or JSON documents from the given reader as a stream. bufferSize determines
 // how far into the stream the decoder will look to figure out whether this
@@ -226,7 +242,10 @@ func (d *YAMLOrJSONDecoder) Decode(into interface{}) error {
 
 			start := strings.LastIndex(js[:syntax.Offset], "\n") + 1
 			line := strings.Count(js[:start], "\n")
-			return fmt.Errorf("json: line %d: %s", line, syntax.Error())
+			return JSONSyntaxError{
+				Line: line,
+				Err:  fmt.Errorf(syntax.Error()),
+			}
 		}
 	}
 	return err

staging/src/k8s.io/apimachinery/pkg/util/yaml/decoder_test.go

@@ -314,3 +314,36 @@ func testReadLines(t *testing.T, lineLengths []int) {
 		}
 	}
 }
+
+func TestTypedJSONOrYamlErrors(t *testing.T) {
+	s := NewYAMLOrJSONDecoder(bytes.NewReader([]byte(`{
+	"foo": {
+		"stuff": 1
+		"otherStuff": 2
+	}
+}
+  `)), 100)
+	obj := generic{}
+	err := s.Decode(&obj)
+	if err == nil {
+		t.Fatal("expected error with json: prefix, got no error")
+	}
+	if _, ok := err.(JSONSyntaxError); !ok {
+		t.Fatalf("expected %q to be of type JSONSyntaxError", err.Error())
+	}
+
+	s = NewYAMLOrJSONDecoder(bytes.NewReader([]byte(`---
+stuff: 1
+		test-foo: 1
+
+---
+  `)), 100)
+	obj = generic{}
+	err = s.Decode(&obj)
+	if err == nil {
+		t.Fatal("expected error with yaml: prefix, got no error")
+	}
+	if _, ok := err.(YAMLSyntaxError); !ok {
+		t.Fatalf("expected %q to be of type YAMLSyntaxError", err.Error())
+	}
+}