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1/*
2 *
3 * Copyright 2017 gRPC authors.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 *     http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 */
18
19// Package status implements errors returned by gRPC.  These errors are
20// serialized and transmitted on the wire between server and client, and allow
21// for additional data to be transmitted via the Details field in the status
22// proto.  gRPC service handlers should return an error created by this
23// package, and gRPC clients should expect a corresponding error to be
24// returned from the RPC call.
25//
26// This package upholds the invariants that a non-nil error may not
27// contain an OK code, and an OK code must result in a nil error.
28package status
29
30import (
31	"errors"
32	"fmt"
33
34	"github.com/golang/protobuf/proto"
35	"github.com/golang/protobuf/ptypes"
36	spb "google.golang.org/genproto/googleapis/rpc/status"
37	"google.golang.org/grpc/codes"
38)
39
40// statusError is an alias of a status proto.  It implements error and Status,
41// and a nil statusError should never be returned by this package.
42type statusError spb.Status
43
44func (se *statusError) Error() string {
45	p := (*spb.Status)(se)
46	return fmt.Sprintf("rpc error: code = %s desc = %s", codes.Code(p.GetCode()), p.GetMessage())
47}
48
49func (se *statusError) GRPCStatus() *Status {
50	return &Status{s: (*spb.Status)(se)}
51}
52
53// Status represents an RPC status code, message, and details.  It is immutable
54// and should be created with New, Newf, or FromProto.
55type Status struct {
56	s *spb.Status
57}
58
59// Code returns the status code contained in s.
60func (s *Status) Code() codes.Code {
61	if s == nil || s.s == nil {
62		return codes.OK
63	}
64	return codes.Code(s.s.Code)
65}
66
67// Message returns the message contained in s.
68func (s *Status) Message() string {
69	if s == nil || s.s == nil {
70		return ""
71	}
72	return s.s.Message
73}
74
75// Proto returns s's status as an spb.Status proto message.
76func (s *Status) Proto() *spb.Status {
77	if s == nil {
78		return nil
79	}
80	return proto.Clone(s.s).(*spb.Status)
81}
82
83// Err returns an immutable error representing s; returns nil if s.Code() is
84// OK.
85func (s *Status) Err() error {
86	if s.Code() == codes.OK {
87		return nil
88	}
89	return (*statusError)(s.s)
90}
91
92// New returns a Status representing c and msg.
93func New(c codes.Code, msg string) *Status {
94	return &Status{s: &spb.Status{Code: int32(c), Message: msg}}
95}
96
97// Newf returns New(c, fmt.Sprintf(format, a...)).
98func Newf(c codes.Code, format string, a ...interface{}) *Status {
99	return New(c, fmt.Sprintf(format, a...))
100}
101
102// Error returns an error representing c and msg.  If c is OK, returns nil.
103func Error(c codes.Code, msg string) error {
104	return New(c, msg).Err()
105}
106
107// Errorf returns Error(c, fmt.Sprintf(format, a...)).
108func Errorf(c codes.Code, format string, a ...interface{}) error {
109	return Error(c, fmt.Sprintf(format, a...))
110}
111
112// ErrorProto returns an error representing s.  If s.Code is OK, returns nil.
113func ErrorProto(s *spb.Status) error {
114	return FromProto(s).Err()
115}
116
117// FromProto returns a Status representing s.
118func FromProto(s *spb.Status) *Status {
119	return &Status{s: proto.Clone(s).(*spb.Status)}
120}
121
122// FromError returns a Status representing err if it was produced from this
123// package or has a method `GRPCStatus() *Status`. Otherwise, ok is false and a
124// Status is returned with codes.Unknown and the original error message.
125func FromError(err error) (s *Status, ok bool) {
126	if err == nil {
127		return &Status{s: &spb.Status{Code: int32(codes.OK)}}, true
128	}
129	if se, ok := err.(interface{ GRPCStatus() *Status }); ok {
130		return se.GRPCStatus(), true
131	}
132	return New(codes.Unknown, err.Error()), false
133}
134
135// Convert is a convenience function which removes the need to handle the
136// boolean return value from FromError.
137func Convert(err error) *Status {
138	s, _ := FromError(err)
139	return s
140}
141
142// WithDetails returns a new status with the provided details messages appended to the status.
143// If any errors are encountered, it returns nil and the first error encountered.
144func (s *Status) WithDetails(details ...proto.Message) (*Status, error) {
145	if s.Code() == codes.OK {
146		return nil, errors.New("no error details for status with code OK")
147	}
148	// s.Code() != OK implies that s.Proto() != nil.
149	p := s.Proto()
150	for _, detail := range details {
151		any, err := ptypes.MarshalAny(detail)
152		if err != nil {
153			return nil, err
154		}
155		p.Details = append(p.Details, any)
156	}
157	return &Status{s: p}, nil
158}
159
160// Details returns a slice of details messages attached to the status.
161// If a detail cannot be decoded, the error is returned in place of the detail.
162func (s *Status) Details() []interface{} {
163	if s == nil || s.s == nil {
164		return nil
165	}
166	details := make([]interface{}, 0, len(s.s.Details))
167	for _, any := range s.s.Details {
168		detail := &ptypes.DynamicAny{}
169		if err := ptypes.UnmarshalAny(any, detail); err != nil {
170			details = append(details, err)
171			continue
172		}
173		details = append(details, detail.Message)
174	}
175	return details
176}
177
178// Code returns the Code of the error if it is a Status error, codes.OK if err
179// is nil, or codes.Unknown otherwise.
180func Code(err error) codes.Code {
181	// Don't use FromError to avoid allocation of OK status.
182	if err == nil {
183		return codes.OK
184	}
185	if se, ok := err.(interface{ GRPCStatus() *Status }); ok {
186		return se.GRPCStatus().Code()
187	}
188	return codes.Unknown
189}
190