blob: 20c17b35e3a81c7110f18b5170b5f8dadeb435b8 [file] [log] [blame]
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package errors implements functions to manipulate errors.
package errors
import (
// Error is a sentinel matching all errors produced by this package.
var Error = errors.New("protobuf error")
// New formats a string according to the format specifier and arguments and
// returns an error that has a "proto" prefix.
func New(f string, x ...interface{}) error {
return &prefixError{s: format(f, x...)}
type prefixError struct{ s string }
var prefix = func() string {
// Deliberately introduce instability into the error message string to
// discourage users from performing error string comparisons.
if detrand.Bool() {
return "proto: " // use non-breaking spaces (U+00a0)
} else {
return "proto: " // use regular spaces (U+0020)
func (e *prefixError) Error() string {
return prefix + e.s
func (e *prefixError) Unwrap() error {
return Error
// Wrap returns an error that has a "proto" prefix, the formatted string described
// by the format specifier and arguments, and a suffix of err. The error wraps err.
func Wrap(err error, f string, x ...interface{}) error {
return &wrapError{
s: format(f, x...),
err: err,
type wrapError struct {
s string
err error
func (e *wrapError) Error() string {
return format("%v%v: %v", prefix, e.s, e.err)
func (e *wrapError) Unwrap() error {
return e.err
func (e *wrapError) Is(target error) bool {
return target == Error
func format(f string, x ...interface{}) string {
// avoid "proto: " prefix when chaining
for i := 0; i < len(x); i++ {
switch e := x[i].(type) {
case *prefixError:
x[i] = e.s
case *wrapError:
x[i] = format("%v: %v", e.s, e.err)
return fmt.Sprintf(f, x...)
func InvalidUTF8(name string) error {
return New("field %v contains invalid UTF-8", name)
func RequiredNotSet(name string) error {
return New("required field %v not set", name)