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Matteo Scandoloa4285862020-12-01 18:10:10 -08001// 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, ok := in.Addr().Interface().(extensionsBytes); ok {
112 emOut := out.Addr().Interface().(extensionsBytes)
113 bIn := emIn.GetExtensions()
114 bOut := emOut.GetExtensions()
115 *bOut = append(*bOut, *bIn...)
116 } else if emIn, err := extendable(in.Addr().Interface()); err == nil {
117 emOut, _ := extendable(out.Addr().Interface())
118 mIn, muIn := emIn.extensionsRead()
119 if mIn != nil {
120 mOut := emOut.extensionsWrite()
121 muIn.Lock()
122 mergeExtension(mOut, mIn)
123 muIn.Unlock()
124 }
125 }
126
127 uf := in.FieldByName("XXX_unrecognized")
128 if !uf.IsValid() {
129 return
130 }
131 uin := uf.Bytes()
132 if len(uin) > 0 {
133 out.FieldByName("XXX_unrecognized").SetBytes(append([]byte(nil), uin...))
134 }
135}
136
137// mergeAny performs a merge between two values of the same type.
138// viaPtr indicates whether the values were indirected through a pointer (implying proto2).
139// prop is set if this is a struct field (it may be nil).
140func mergeAny(out, in reflect.Value, viaPtr bool, prop *Properties) {
141 if in.Type() == protoMessageType {
142 if !in.IsNil() {
143 if out.IsNil() {
144 out.Set(reflect.ValueOf(Clone(in.Interface().(Message))))
145 } else {
146 Merge(out.Interface().(Message), in.Interface().(Message))
147 }
148 }
149 return
150 }
151 switch in.Kind() {
152 case reflect.Bool, reflect.Float32, reflect.Float64, reflect.Int32, reflect.Int64,
153 reflect.String, reflect.Uint32, reflect.Uint64:
154 if !viaPtr && isProto3Zero(in) {
155 return
156 }
157 out.Set(in)
158 case reflect.Interface:
159 // Probably a oneof field; copy non-nil values.
160 if in.IsNil() {
161 return
162 }
163 // Allocate destination if it is not set, or set to a different type.
164 // Otherwise we will merge as normal.
165 if out.IsNil() || out.Elem().Type() != in.Elem().Type() {
166 out.Set(reflect.New(in.Elem().Elem().Type())) // interface -> *T -> T -> new(T)
167 }
168 mergeAny(out.Elem(), in.Elem(), false, nil)
169 case reflect.Map:
170 if in.Len() == 0 {
171 return
172 }
173 if out.IsNil() {
174 out.Set(reflect.MakeMap(in.Type()))
175 }
176 // For maps with value types of *T or []byte we need to deep copy each value.
177 elemKind := in.Type().Elem().Kind()
178 for _, key := range in.MapKeys() {
179 var val reflect.Value
180 switch elemKind {
181 case reflect.Ptr:
182 val = reflect.New(in.Type().Elem().Elem())
183 mergeAny(val, in.MapIndex(key), false, nil)
184 case reflect.Slice:
185 val = in.MapIndex(key)
186 val = reflect.ValueOf(append([]byte{}, val.Bytes()...))
187 default:
188 val = in.MapIndex(key)
189 }
190 out.SetMapIndex(key, val)
191 }
192 case reflect.Ptr:
193 if in.IsNil() {
194 return
195 }
196 if out.IsNil() {
197 out.Set(reflect.New(in.Elem().Type()))
198 }
199 mergeAny(out.Elem(), in.Elem(), true, nil)
200 case reflect.Slice:
201 if in.IsNil() {
202 return
203 }
204 if in.Type().Elem().Kind() == reflect.Uint8 {
205 // []byte is a scalar bytes field, not a repeated field.
206
207 // Edge case: if this is in a proto3 message, a zero length
208 // bytes field is considered the zero value, and should not
209 // be merged.
210 if prop != nil && prop.proto3 && in.Len() == 0 {
211 return
212 }
213
214 // Make a deep copy.
215 // Append to []byte{} instead of []byte(nil) so that we never end up
216 // with a nil result.
217 out.SetBytes(append([]byte{}, in.Bytes()...))
218 return
219 }
220 n := in.Len()
221 if out.IsNil() {
222 out.Set(reflect.MakeSlice(in.Type(), 0, n))
223 }
224 switch in.Type().Elem().Kind() {
225 case reflect.Bool, reflect.Float32, reflect.Float64, reflect.Int32, reflect.Int64,
226 reflect.String, reflect.Uint32, reflect.Uint64:
227 out.Set(reflect.AppendSlice(out, in))
228 default:
229 for i := 0; i < n; i++ {
230 x := reflect.Indirect(reflect.New(in.Type().Elem()))
231 mergeAny(x, in.Index(i), false, nil)
232 out.Set(reflect.Append(out, x))
233 }
234 }
235 case reflect.Struct:
236 mergeStruct(out, in)
237 default:
238 // unknown type, so not a protocol buffer
239 log.Printf("proto: don't know how to copy %v", in)
240 }
241}
242
243func mergeExtension(out, in map[int32]Extension) {
244 for extNum, eIn := range in {
245 eOut := Extension{desc: eIn.desc}
246 if eIn.value != nil {
247 v := reflect.New(reflect.TypeOf(eIn.value)).Elem()
248 mergeAny(v, reflect.ValueOf(eIn.value), false, nil)
249 eOut.value = v.Interface()
250 }
251 if eIn.enc != nil {
252 eOut.enc = make([]byte, len(eIn.enc))
253 copy(eOut.enc, eIn.enc)
254 }
255
256 out[extNum] = eOut
257 }
258}