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William Kurkianea869482019-04-09 15:16:11 -04001// Go support for Protocol Buffers - Google's data interchange format
2//
3// Copyright 2011 The Go Authors. All rights reserved.
4// https://github.com/golang/protobuf
5//
6// Redistribution and use in source and binary forms, with or without
7// modification, are permitted provided that the following conditions are
8// met:
9//
10// * Redistributions of source code must retain the above copyright
11// notice, this list of conditions and the following disclaimer.
12// * Redistributions in binary form must reproduce the above
13// copyright notice, this list of conditions and the following disclaimer
14// in the documentation and/or other materials provided with the
15// distribution.
16// * Neither the name of Google Inc. nor the names of its
17// contributors may be used to endorse or promote products derived from
18// this software without specific prior written permission.
19//
20// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
23// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
24// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
25// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
26// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
30// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31
32// Protocol buffer deep copy and merge.
33// TODO: RawMessage.
34
35package proto
36
37import (
38 "fmt"
39 "log"
40 "reflect"
41 "strings"
42)
43
44// Clone returns a deep copy of a protocol buffer.
45func Clone(src Message) Message {
46 in := reflect.ValueOf(src)
47 if in.IsNil() {
48 return src
49 }
50 out := reflect.New(in.Type().Elem())
51 dst := out.Interface().(Message)
52 Merge(dst, src)
53 return dst
54}
55
56// Merger is the interface representing objects that can merge messages of the same type.
57type Merger interface {
58 // Merge merges src into this message.
59 // Required and optional fields that are set in src will be set to that value in dst.
60 // Elements of repeated fields will be appended.
61 //
62 // Merge may panic if called with a different argument type than the receiver.
63 Merge(src Message)
64}
65
66// generatedMerger is the custom merge method that generated protos will have.
67// We must add this method since a generate Merge method will conflict with
68// many existing protos that have a Merge data field already defined.
69type generatedMerger interface {
70 XXX_Merge(src Message)
71}
72
73// Merge merges src into dst.
74// Required and optional fields that are set in src will be set to that value in dst.
75// Elements of repeated fields will be appended.
76// Merge panics if src and dst are not the same type, or if dst is nil.
77func Merge(dst, src Message) {
78 if m, ok := dst.(Merger); ok {
79 m.Merge(src)
80 return
81 }
82
83 in := reflect.ValueOf(src)
84 out := reflect.ValueOf(dst)
85 if out.IsNil() {
86 panic("proto: nil destination")
87 }
88 if in.Type() != out.Type() {
89 panic(fmt.Sprintf("proto.Merge(%T, %T) type mismatch", dst, src))
90 }
91 if in.IsNil() {
92 return // Merge from nil src is a noop
93 }
94 if m, ok := dst.(generatedMerger); ok {
95 m.XXX_Merge(src)
96 return
97 }
98 mergeStruct(out.Elem(), in.Elem())
99}
100
101func mergeStruct(out, in reflect.Value) {
102 sprop := GetProperties(in.Type())
103 for i := 0; i < in.NumField(); i++ {
104 f := in.Type().Field(i)
105 if strings.HasPrefix(f.Name, "XXX_") {
106 continue
107 }
108 mergeAny(out.Field(i), in.Field(i), false, sprop.Prop[i])
109 }
110
111 if emIn, err := extendable(in.Addr().Interface()); err == nil {
112 emOut, _ := extendable(out.Addr().Interface())
113 mIn, muIn := emIn.extensionsRead()
114 if mIn != nil {
115 mOut := emOut.extensionsWrite()
116 muIn.Lock()
117 mergeExtension(mOut, mIn)
118 muIn.Unlock()
119 }
120 }
121
122 uf := in.FieldByName("XXX_unrecognized")
123 if !uf.IsValid() {
124 return
125 }
126 uin := uf.Bytes()
127 if len(uin) > 0 {
128 out.FieldByName("XXX_unrecognized").SetBytes(append([]byte(nil), uin...))
129 }
130}
131
132// mergeAny performs a merge between two values of the same type.
133// viaPtr indicates whether the values were indirected through a pointer (implying proto2).
134// prop is set if this is a struct field (it may be nil).
135func mergeAny(out, in reflect.Value, viaPtr bool, prop *Properties) {
136 if in.Type() == protoMessageType {
137 if !in.IsNil() {
138 if out.IsNil() {
139 out.Set(reflect.ValueOf(Clone(in.Interface().(Message))))
140 } else {
141 Merge(out.Interface().(Message), in.Interface().(Message))
142 }
143 }
144 return
145 }
146 switch in.Kind() {
147 case reflect.Bool, reflect.Float32, reflect.Float64, reflect.Int32, reflect.Int64,
148 reflect.String, reflect.Uint32, reflect.Uint64:
149 if !viaPtr && isProto3Zero(in) {
150 return
151 }
152 out.Set(in)
153 case reflect.Interface:
154 // Probably a oneof field; copy non-nil values.
155 if in.IsNil() {
156 return
157 }
158 // Allocate destination if it is not set, or set to a different type.
159 // Otherwise we will merge as normal.
160 if out.IsNil() || out.Elem().Type() != in.Elem().Type() {
161 out.Set(reflect.New(in.Elem().Elem().Type())) // interface -> *T -> T -> new(T)
162 }
163 mergeAny(out.Elem(), in.Elem(), false, nil)
164 case reflect.Map:
165 if in.Len() == 0 {
166 return
167 }
168 if out.IsNil() {
169 out.Set(reflect.MakeMap(in.Type()))
170 }
171 // For maps with value types of *T or []byte we need to deep copy each value.
172 elemKind := in.Type().Elem().Kind()
173 for _, key := range in.MapKeys() {
174 var val reflect.Value
175 switch elemKind {
176 case reflect.Ptr:
177 val = reflect.New(in.Type().Elem().Elem())
178 mergeAny(val, in.MapIndex(key), false, nil)
179 case reflect.Slice:
180 val = in.MapIndex(key)
181 val = reflect.ValueOf(append([]byte{}, val.Bytes()...))
182 default:
183 val = in.MapIndex(key)
184 }
185 out.SetMapIndex(key, val)
186 }
187 case reflect.Ptr:
188 if in.IsNil() {
189 return
190 }
191 if out.IsNil() {
192 out.Set(reflect.New(in.Elem().Type()))
193 }
194 mergeAny(out.Elem(), in.Elem(), true, nil)
195 case reflect.Slice:
196 if in.IsNil() {
197 return
198 }
199 if in.Type().Elem().Kind() == reflect.Uint8 {
200 // []byte is a scalar bytes field, not a repeated field.
201
202 // Edge case: if this is in a proto3 message, a zero length
203 // bytes field is considered the zero value, and should not
204 // be merged.
205 if prop != nil && prop.proto3 && in.Len() == 0 {
206 return
207 }
208
209 // Make a deep copy.
210 // Append to []byte{} instead of []byte(nil) so that we never end up
211 // with a nil result.
212 out.SetBytes(append([]byte{}, in.Bytes()...))
213 return
214 }
215 n := in.Len()
216 if out.IsNil() {
217 out.Set(reflect.MakeSlice(in.Type(), 0, n))
218 }
219 switch in.Type().Elem().Kind() {
220 case reflect.Bool, reflect.Float32, reflect.Float64, reflect.Int32, reflect.Int64,
221 reflect.String, reflect.Uint32, reflect.Uint64:
222 out.Set(reflect.AppendSlice(out, in))
223 default:
224 for i := 0; i < n; i++ {
225 x := reflect.Indirect(reflect.New(in.Type().Elem()))
226 mergeAny(x, in.Index(i), false, nil)
227 out.Set(reflect.Append(out, x))
228 }
229 }
230 case reflect.Struct:
231 mergeStruct(out, in)
232 default:
233 // unknown type, so not a protocol buffer
234 log.Printf("proto: don't know how to copy %v", in)
235 }
236}
237
238func mergeExtension(out, in map[int32]Extension) {
239 for extNum, eIn := range in {
240 eOut := Extension{desc: eIn.desc}
241 if eIn.value != nil {
242 v := reflect.New(reflect.TypeOf(eIn.value)).Elem()
243 mergeAny(v, reflect.ValueOf(eIn.value), false, nil)
244 eOut.value = v.Interface()
245 }
246 if eIn.enc != nil {
247 eOut.enc = make([]byte, len(eIn.enc))
248 copy(eOut.enc, eIn.enc)
249 }
250
251 out[extNum] = eOut
252 }
253}