1// Copyright 2017 Google LLC
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//      http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15package internal
16
17import (
18	"fmt"
19
20	"google.golang.org/api/googleapi"
21	"google.golang.org/grpc/status"
22)
23
24// Annotate prepends msg to the error message in err, attempting
25// to preserve other information in err, like an error code.
26//
27// Annotate panics if err is nil.
28//
29// Annotate knows about these error types:
30// - "google.golang.org/grpc/status".Status
31// - "google.golang.org/api/googleapi".Error
32// If the error is not one of these types, Annotate behaves
33// like
34//   fmt.Errorf("%s: %v", msg, err)
35func Annotate(err error, msg string) error {
36	if err == nil {
37		panic("Annotate called with nil")
38	}
39	if s, ok := status.FromError(err); ok {
40		p := s.Proto()
41		p.Message = msg + ": " + p.Message
42		return status.ErrorProto(p)
43	}
44	if g, ok := err.(*googleapi.Error); ok {
45		g.Message = msg + ": " + g.Message
46		return g
47	}
48	return fmt.Errorf("%s: %v", msg, err)
49}
50
51// Annotatef uses format and args to format a string, then calls Annotate.
52func Annotatef(err error, format string, args ...interface{}) error {
53	return Annotate(err, fmt.Sprintf(format, args...))
54}
55