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khenaidoo26721882021-08-11 17:42:52 -04001// Copyright 2018 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package impl
6
7import (
8 "fmt"
9 "reflect"
10 "strconv"
11 "strings"
12 "sync"
13 "sync/atomic"
14
15 "google.golang.org/protobuf/internal/genid"
16 "google.golang.org/protobuf/reflect/protoreflect"
17 pref "google.golang.org/protobuf/reflect/protoreflect"
18 preg "google.golang.org/protobuf/reflect/protoregistry"
19)
20
21// MessageInfo provides protobuf related functionality for a given Go type
22// that represents a message. A given instance of MessageInfo is tied to
23// exactly one Go type, which must be a pointer to a struct type.
24//
25// The exported fields must be populated before any methods are called
26// and cannot be mutated after set.
27type MessageInfo struct {
28 // GoReflectType is the underlying message Go type and must be populated.
29 GoReflectType reflect.Type // pointer to struct
30
31 // Desc is the underlying message descriptor type and must be populated.
32 Desc pref.MessageDescriptor
33
34 // Exporter must be provided in a purego environment in order to provide
35 // access to unexported fields.
36 Exporter exporter
37
38 // OneofWrappers is list of pointers to oneof wrapper struct types.
39 OneofWrappers []interface{}
40
41 initMu sync.Mutex // protects all unexported fields
42 initDone uint32
43
44 reflectMessageInfo // for reflection implementation
45 coderMessageInfo // for fast-path method implementations
46}
47
48// exporter is a function that returns a reference to the ith field of v,
49// where v is a pointer to a struct. It returns nil if it does not support
50// exporting the requested field (e.g., already exported).
51type exporter func(v interface{}, i int) interface{}
52
53// getMessageInfo returns the MessageInfo for any message type that
54// is generated by our implementation of protoc-gen-go (for v2 and on).
55// If it is unable to obtain a MessageInfo, it returns nil.
56func getMessageInfo(mt reflect.Type) *MessageInfo {
57 m, ok := reflect.Zero(mt).Interface().(pref.ProtoMessage)
58 if !ok {
59 return nil
60 }
61 mr, ok := m.ProtoReflect().(interface{ ProtoMessageInfo() *MessageInfo })
62 if !ok {
63 return nil
64 }
65 return mr.ProtoMessageInfo()
66}
67
68func (mi *MessageInfo) init() {
69 // This function is called in the hot path. Inline the sync.Once logic,
70 // since allocating a closure for Once.Do is expensive.
71 // Keep init small to ensure that it can be inlined.
72 if atomic.LoadUint32(&mi.initDone) == 0 {
73 mi.initOnce()
74 }
75}
76
77func (mi *MessageInfo) initOnce() {
78 mi.initMu.Lock()
79 defer mi.initMu.Unlock()
80 if mi.initDone == 1 {
81 return
82 }
83
84 t := mi.GoReflectType
85 if t.Kind() != reflect.Ptr && t.Elem().Kind() != reflect.Struct {
86 panic(fmt.Sprintf("got %v, want *struct kind", t))
87 }
88 t = t.Elem()
89
90 si := mi.makeStructInfo(t)
91 mi.makeReflectFuncs(t, si)
92 mi.makeCoderMethods(t, si)
93
94 atomic.StoreUint32(&mi.initDone, 1)
95}
96
97// getPointer returns the pointer for a message, which should be of
98// the type of the MessageInfo. If the message is of a different type,
99// it returns ok==false.
100func (mi *MessageInfo) getPointer(m pref.Message) (p pointer, ok bool) {
101 switch m := m.(type) {
102 case *messageState:
103 return m.pointer(), m.messageInfo() == mi
104 case *messageReflectWrapper:
105 return m.pointer(), m.messageInfo() == mi
106 }
107 return pointer{}, false
108}
109
110type (
111 SizeCache = int32
112 WeakFields = map[int32]protoreflect.ProtoMessage
113 UnknownFields = unknownFieldsA // TODO: switch to unknownFieldsB
114 unknownFieldsA = []byte
115 unknownFieldsB = *[]byte
116 ExtensionFields = map[int32]ExtensionField
117)
118
119var (
120 sizecacheType = reflect.TypeOf(SizeCache(0))
121 weakFieldsType = reflect.TypeOf(WeakFields(nil))
122 unknownFieldsAType = reflect.TypeOf(unknownFieldsA(nil))
123 unknownFieldsBType = reflect.TypeOf(unknownFieldsB(nil))
124 extensionFieldsType = reflect.TypeOf(ExtensionFields(nil))
125)
126
127type structInfo struct {
128 sizecacheOffset offset
129 sizecacheType reflect.Type
130 weakOffset offset
131 weakType reflect.Type
132 unknownOffset offset
133 unknownType reflect.Type
134 extensionOffset offset
135 extensionType reflect.Type
136
137 fieldsByNumber map[pref.FieldNumber]reflect.StructField
138 oneofsByName map[pref.Name]reflect.StructField
139 oneofWrappersByType map[reflect.Type]pref.FieldNumber
140 oneofWrappersByNumber map[pref.FieldNumber]reflect.Type
141}
142
143func (mi *MessageInfo) makeStructInfo(t reflect.Type) structInfo {
144 si := structInfo{
145 sizecacheOffset: invalidOffset,
146 weakOffset: invalidOffset,
147 unknownOffset: invalidOffset,
148 extensionOffset: invalidOffset,
149
150 fieldsByNumber: map[pref.FieldNumber]reflect.StructField{},
151 oneofsByName: map[pref.Name]reflect.StructField{},
152 oneofWrappersByType: map[reflect.Type]pref.FieldNumber{},
153 oneofWrappersByNumber: map[pref.FieldNumber]reflect.Type{},
154 }
155
156fieldLoop:
157 for i := 0; i < t.NumField(); i++ {
158 switch f := t.Field(i); f.Name {
159 case genid.SizeCache_goname, genid.SizeCacheA_goname:
160 if f.Type == sizecacheType {
161 si.sizecacheOffset = offsetOf(f, mi.Exporter)
162 si.sizecacheType = f.Type
163 }
164 case genid.WeakFields_goname, genid.WeakFieldsA_goname:
165 if f.Type == weakFieldsType {
166 si.weakOffset = offsetOf(f, mi.Exporter)
167 si.weakType = f.Type
168 }
169 case genid.UnknownFields_goname, genid.UnknownFieldsA_goname:
170 if f.Type == unknownFieldsAType || f.Type == unknownFieldsBType {
171 si.unknownOffset = offsetOf(f, mi.Exporter)
172 si.unknownType = f.Type
173 }
174 case genid.ExtensionFields_goname, genid.ExtensionFieldsA_goname, genid.ExtensionFieldsB_goname:
175 if f.Type == extensionFieldsType {
176 si.extensionOffset = offsetOf(f, mi.Exporter)
177 si.extensionType = f.Type
178 }
179 default:
180 for _, s := range strings.Split(f.Tag.Get("protobuf"), ",") {
181 if len(s) > 0 && strings.Trim(s, "0123456789") == "" {
182 n, _ := strconv.ParseUint(s, 10, 64)
183 si.fieldsByNumber[pref.FieldNumber(n)] = f
184 continue fieldLoop
185 }
186 }
187 if s := f.Tag.Get("protobuf_oneof"); len(s) > 0 {
188 si.oneofsByName[pref.Name(s)] = f
189 continue fieldLoop
190 }
191 }
192 }
193
194 // Derive a mapping of oneof wrappers to fields.
195 oneofWrappers := mi.OneofWrappers
196 for _, method := range []string{"XXX_OneofFuncs", "XXX_OneofWrappers"} {
197 if fn, ok := reflect.PtrTo(t).MethodByName(method); ok {
198 for _, v := range fn.Func.Call([]reflect.Value{reflect.Zero(fn.Type.In(0))}) {
199 if vs, ok := v.Interface().([]interface{}); ok {
200 oneofWrappers = vs
201 }
202 }
203 }
204 }
205 for _, v := range oneofWrappers {
206 tf := reflect.TypeOf(v).Elem()
207 f := tf.Field(0)
208 for _, s := range strings.Split(f.Tag.Get("protobuf"), ",") {
209 if len(s) > 0 && strings.Trim(s, "0123456789") == "" {
210 n, _ := strconv.ParseUint(s, 10, 64)
211 si.oneofWrappersByType[tf] = pref.FieldNumber(n)
212 si.oneofWrappersByNumber[pref.FieldNumber(n)] = tf
213 break
214 }
215 }
216 }
217
218 return si
219}
220
221func (mi *MessageInfo) New() protoreflect.Message {
222 return mi.MessageOf(reflect.New(mi.GoReflectType.Elem()).Interface())
223}
224func (mi *MessageInfo) Zero() protoreflect.Message {
225 return mi.MessageOf(reflect.Zero(mi.GoReflectType).Interface())
226}
227func (mi *MessageInfo) Descriptor() protoreflect.MessageDescriptor {
228 return mi.Desc
229}
230func (mi *MessageInfo) Enum(i int) protoreflect.EnumType {
231 mi.init()
232 fd := mi.Desc.Fields().Get(i)
233 return Export{}.EnumTypeOf(mi.fieldTypes[fd.Number()])
234}
235func (mi *MessageInfo) Message(i int) protoreflect.MessageType {
236 mi.init()
237 fd := mi.Desc.Fields().Get(i)
238 switch {
239 case fd.IsWeak():
240 mt, _ := preg.GlobalTypes.FindMessageByName(fd.Message().FullName())
241 return mt
242 case fd.IsMap():
243 return mapEntryType{fd.Message(), mi.fieldTypes[fd.Number()]}
244 default:
245 return Export{}.MessageTypeOf(mi.fieldTypes[fd.Number()])
246 }
247}
248
249type mapEntryType struct {
250 desc protoreflect.MessageDescriptor
251 valType interface{} // zero value of enum or message type
252}
253
254func (mt mapEntryType) New() protoreflect.Message {
255 return nil
256}
257func (mt mapEntryType) Zero() protoreflect.Message {
258 return nil
259}
260func (mt mapEntryType) Descriptor() protoreflect.MessageDescriptor {
261 return mt.desc
262}
263func (mt mapEntryType) Enum(i int) protoreflect.EnumType {
264 fd := mt.desc.Fields().Get(i)
265 if fd.Enum() == nil {
266 return nil
267 }
268 return Export{}.EnumTypeOf(mt.valType)
269}
270func (mt mapEntryType) Message(i int) protoreflect.MessageType {
271 fd := mt.desc.Fields().Get(i)
272 if fd.Message() == nil {
273 return nil
274 }
275 return Export{}.MessageTypeOf(mt.valType)
276}