khenaidoo | 7d3c558 | 2021-08-11 18:09:44 -0400 | [diff] [blame] | 1 | // Copyright 2019 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 | |
| 5 | package impl |
| 6 | |
| 7 | import ( |
| 8 | "fmt" |
| 9 | "reflect" |
| 10 | |
| 11 | "google.golang.org/protobuf/internal/detrand" |
| 12 | "google.golang.org/protobuf/internal/pragma" |
| 13 | pref "google.golang.org/protobuf/reflect/protoreflect" |
| 14 | ) |
| 15 | |
| 16 | type reflectMessageInfo struct { |
| 17 | fields map[pref.FieldNumber]*fieldInfo |
| 18 | oneofs map[pref.Name]*oneofInfo |
| 19 | |
| 20 | // fieldTypes contains the zero value of an enum or message field. |
| 21 | // For lists, it contains the element type. |
| 22 | // For maps, it contains the entry value type. |
| 23 | fieldTypes map[pref.FieldNumber]interface{} |
| 24 | |
| 25 | // denseFields is a subset of fields where: |
| 26 | // 0 < fieldDesc.Number() < len(denseFields) |
| 27 | // It provides faster access to the fieldInfo, but may be incomplete. |
| 28 | denseFields []*fieldInfo |
| 29 | |
| 30 | // rangeInfos is a list of all fields (not belonging to a oneof) and oneofs. |
| 31 | rangeInfos []interface{} // either *fieldInfo or *oneofInfo |
| 32 | |
| 33 | getUnknown func(pointer) pref.RawFields |
| 34 | setUnknown func(pointer, pref.RawFields) |
| 35 | extensionMap func(pointer) *extensionMap |
| 36 | |
| 37 | nilMessage atomicNilMessage |
| 38 | } |
| 39 | |
| 40 | // makeReflectFuncs generates the set of functions to support reflection. |
| 41 | func (mi *MessageInfo) makeReflectFuncs(t reflect.Type, si structInfo) { |
| 42 | mi.makeKnownFieldsFunc(si) |
| 43 | mi.makeUnknownFieldsFunc(t, si) |
| 44 | mi.makeExtensionFieldsFunc(t, si) |
| 45 | mi.makeFieldTypes(si) |
| 46 | } |
| 47 | |
| 48 | // makeKnownFieldsFunc generates functions for operations that can be performed |
| 49 | // on each protobuf message field. It takes in a reflect.Type representing the |
| 50 | // Go struct and matches message fields with struct fields. |
| 51 | // |
| 52 | // This code assumes that the struct is well-formed and panics if there are |
| 53 | // any discrepancies. |
| 54 | func (mi *MessageInfo) makeKnownFieldsFunc(si structInfo) { |
| 55 | mi.fields = map[pref.FieldNumber]*fieldInfo{} |
| 56 | md := mi.Desc |
| 57 | fds := md.Fields() |
| 58 | for i := 0; i < fds.Len(); i++ { |
| 59 | fd := fds.Get(i) |
| 60 | fs := si.fieldsByNumber[fd.Number()] |
| 61 | isOneof := fd.ContainingOneof() != nil && !fd.ContainingOneof().IsSynthetic() |
| 62 | if isOneof { |
| 63 | fs = si.oneofsByName[fd.ContainingOneof().Name()] |
| 64 | } |
| 65 | var fi fieldInfo |
| 66 | switch { |
| 67 | case fs.Type == nil: |
| 68 | fi = fieldInfoForMissing(fd) // never occurs for officially generated message types |
| 69 | case isOneof: |
| 70 | fi = fieldInfoForOneof(fd, fs, mi.Exporter, si.oneofWrappersByNumber[fd.Number()]) |
| 71 | case fd.IsMap(): |
| 72 | fi = fieldInfoForMap(fd, fs, mi.Exporter) |
| 73 | case fd.IsList(): |
| 74 | fi = fieldInfoForList(fd, fs, mi.Exporter) |
| 75 | case fd.IsWeak(): |
| 76 | fi = fieldInfoForWeakMessage(fd, si.weakOffset) |
| 77 | case fd.Message() != nil: |
| 78 | fi = fieldInfoForMessage(fd, fs, mi.Exporter) |
| 79 | default: |
| 80 | fi = fieldInfoForScalar(fd, fs, mi.Exporter) |
| 81 | } |
| 82 | mi.fields[fd.Number()] = &fi |
| 83 | } |
| 84 | |
| 85 | mi.oneofs = map[pref.Name]*oneofInfo{} |
| 86 | for i := 0; i < md.Oneofs().Len(); i++ { |
| 87 | od := md.Oneofs().Get(i) |
| 88 | mi.oneofs[od.Name()] = makeOneofInfo(od, si, mi.Exporter) |
| 89 | } |
| 90 | |
| 91 | mi.denseFields = make([]*fieldInfo, fds.Len()*2) |
| 92 | for i := 0; i < fds.Len(); i++ { |
| 93 | if fd := fds.Get(i); int(fd.Number()) < len(mi.denseFields) { |
| 94 | mi.denseFields[fd.Number()] = mi.fields[fd.Number()] |
| 95 | } |
| 96 | } |
| 97 | |
| 98 | for i := 0; i < fds.Len(); { |
| 99 | fd := fds.Get(i) |
| 100 | if od := fd.ContainingOneof(); od != nil && !od.IsSynthetic() { |
| 101 | mi.rangeInfos = append(mi.rangeInfos, mi.oneofs[od.Name()]) |
| 102 | i += od.Fields().Len() |
| 103 | } else { |
| 104 | mi.rangeInfos = append(mi.rangeInfos, mi.fields[fd.Number()]) |
| 105 | i++ |
| 106 | } |
| 107 | } |
| 108 | |
| 109 | // Introduce instability to iteration order, but keep it deterministic. |
| 110 | if len(mi.rangeInfos) > 1 && detrand.Bool() { |
| 111 | i := detrand.Intn(len(mi.rangeInfos) - 1) |
| 112 | mi.rangeInfos[i], mi.rangeInfos[i+1] = mi.rangeInfos[i+1], mi.rangeInfos[i] |
| 113 | } |
| 114 | } |
| 115 | |
| 116 | func (mi *MessageInfo) makeUnknownFieldsFunc(t reflect.Type, si structInfo) { |
| 117 | switch { |
| 118 | case si.unknownOffset.IsValid() && si.unknownType == unknownFieldsAType: |
| 119 | // Handle as []byte. |
| 120 | mi.getUnknown = func(p pointer) pref.RawFields { |
| 121 | if p.IsNil() { |
| 122 | return nil |
| 123 | } |
| 124 | return *p.Apply(mi.unknownOffset).Bytes() |
| 125 | } |
| 126 | mi.setUnknown = func(p pointer, b pref.RawFields) { |
| 127 | if p.IsNil() { |
| 128 | panic("invalid SetUnknown on nil Message") |
| 129 | } |
| 130 | *p.Apply(mi.unknownOffset).Bytes() = b |
| 131 | } |
| 132 | case si.unknownOffset.IsValid() && si.unknownType == unknownFieldsBType: |
| 133 | // Handle as *[]byte. |
| 134 | mi.getUnknown = func(p pointer) pref.RawFields { |
| 135 | if p.IsNil() { |
| 136 | return nil |
| 137 | } |
| 138 | bp := p.Apply(mi.unknownOffset).BytesPtr() |
| 139 | if *bp == nil { |
| 140 | return nil |
| 141 | } |
| 142 | return **bp |
| 143 | } |
| 144 | mi.setUnknown = func(p pointer, b pref.RawFields) { |
| 145 | if p.IsNil() { |
| 146 | panic("invalid SetUnknown on nil Message") |
| 147 | } |
| 148 | bp := p.Apply(mi.unknownOffset).BytesPtr() |
| 149 | if *bp == nil { |
| 150 | *bp = new([]byte) |
| 151 | } |
| 152 | **bp = b |
| 153 | } |
| 154 | default: |
| 155 | mi.getUnknown = func(pointer) pref.RawFields { |
| 156 | return nil |
| 157 | } |
| 158 | mi.setUnknown = func(p pointer, _ pref.RawFields) { |
| 159 | if p.IsNil() { |
| 160 | panic("invalid SetUnknown on nil Message") |
| 161 | } |
| 162 | } |
| 163 | } |
| 164 | } |
| 165 | |
| 166 | func (mi *MessageInfo) makeExtensionFieldsFunc(t reflect.Type, si structInfo) { |
| 167 | if si.extensionOffset.IsValid() { |
| 168 | mi.extensionMap = func(p pointer) *extensionMap { |
| 169 | if p.IsNil() { |
| 170 | return (*extensionMap)(nil) |
| 171 | } |
| 172 | v := p.Apply(si.extensionOffset).AsValueOf(extensionFieldsType) |
| 173 | return (*extensionMap)(v.Interface().(*map[int32]ExtensionField)) |
| 174 | } |
| 175 | } else { |
| 176 | mi.extensionMap = func(pointer) *extensionMap { |
| 177 | return (*extensionMap)(nil) |
| 178 | } |
| 179 | } |
| 180 | } |
| 181 | func (mi *MessageInfo) makeFieldTypes(si structInfo) { |
| 182 | md := mi.Desc |
| 183 | fds := md.Fields() |
| 184 | for i := 0; i < fds.Len(); i++ { |
| 185 | var ft reflect.Type |
| 186 | fd := fds.Get(i) |
| 187 | fs := si.fieldsByNumber[fd.Number()] |
| 188 | isOneof := fd.ContainingOneof() != nil && !fd.ContainingOneof().IsSynthetic() |
| 189 | if isOneof { |
| 190 | fs = si.oneofsByName[fd.ContainingOneof().Name()] |
| 191 | } |
| 192 | var isMessage bool |
| 193 | switch { |
| 194 | case fs.Type == nil: |
| 195 | continue // never occurs for officially generated message types |
| 196 | case isOneof: |
| 197 | if fd.Enum() != nil || fd.Message() != nil { |
| 198 | ft = si.oneofWrappersByNumber[fd.Number()].Field(0).Type |
| 199 | } |
| 200 | case fd.IsMap(): |
| 201 | if fd.MapValue().Enum() != nil || fd.MapValue().Message() != nil { |
| 202 | ft = fs.Type.Elem() |
| 203 | } |
| 204 | isMessage = fd.MapValue().Message() != nil |
| 205 | case fd.IsList(): |
| 206 | if fd.Enum() != nil || fd.Message() != nil { |
| 207 | ft = fs.Type.Elem() |
| 208 | } |
| 209 | isMessage = fd.Message() != nil |
| 210 | case fd.Enum() != nil: |
| 211 | ft = fs.Type |
| 212 | if fd.HasPresence() && ft.Kind() == reflect.Ptr { |
| 213 | ft = ft.Elem() |
| 214 | } |
| 215 | case fd.Message() != nil: |
| 216 | ft = fs.Type |
| 217 | if fd.IsWeak() { |
| 218 | ft = nil |
| 219 | } |
| 220 | isMessage = true |
| 221 | } |
| 222 | if isMessage && ft != nil && ft.Kind() != reflect.Ptr { |
| 223 | ft = reflect.PtrTo(ft) // never occurs for officially generated message types |
| 224 | } |
| 225 | if ft != nil { |
| 226 | if mi.fieldTypes == nil { |
| 227 | mi.fieldTypes = make(map[pref.FieldNumber]interface{}) |
| 228 | } |
| 229 | mi.fieldTypes[fd.Number()] = reflect.Zero(ft).Interface() |
| 230 | } |
| 231 | } |
| 232 | } |
| 233 | |
| 234 | type extensionMap map[int32]ExtensionField |
| 235 | |
| 236 | func (m *extensionMap) Range(f func(pref.FieldDescriptor, pref.Value) bool) { |
| 237 | if m != nil { |
| 238 | for _, x := range *m { |
| 239 | xd := x.Type().TypeDescriptor() |
| 240 | v := x.Value() |
| 241 | if xd.IsList() && v.List().Len() == 0 { |
| 242 | continue |
| 243 | } |
| 244 | if !f(xd, v) { |
| 245 | return |
| 246 | } |
| 247 | } |
| 248 | } |
| 249 | } |
| 250 | func (m *extensionMap) Has(xt pref.ExtensionType) (ok bool) { |
| 251 | if m == nil { |
| 252 | return false |
| 253 | } |
| 254 | xd := xt.TypeDescriptor() |
| 255 | x, ok := (*m)[int32(xd.Number())] |
| 256 | if !ok { |
| 257 | return false |
| 258 | } |
| 259 | switch { |
| 260 | case xd.IsList(): |
| 261 | return x.Value().List().Len() > 0 |
| 262 | case xd.IsMap(): |
| 263 | return x.Value().Map().Len() > 0 |
| 264 | case xd.Message() != nil: |
| 265 | return x.Value().Message().IsValid() |
| 266 | } |
| 267 | return true |
| 268 | } |
| 269 | func (m *extensionMap) Clear(xt pref.ExtensionType) { |
| 270 | delete(*m, int32(xt.TypeDescriptor().Number())) |
| 271 | } |
| 272 | func (m *extensionMap) Get(xt pref.ExtensionType) pref.Value { |
| 273 | xd := xt.TypeDescriptor() |
| 274 | if m != nil { |
| 275 | if x, ok := (*m)[int32(xd.Number())]; ok { |
| 276 | return x.Value() |
| 277 | } |
| 278 | } |
| 279 | return xt.Zero() |
| 280 | } |
| 281 | func (m *extensionMap) Set(xt pref.ExtensionType, v pref.Value) { |
| 282 | xd := xt.TypeDescriptor() |
| 283 | isValid := true |
| 284 | switch { |
| 285 | case !xt.IsValidValue(v): |
| 286 | isValid = false |
| 287 | case xd.IsList(): |
| 288 | isValid = v.List().IsValid() |
| 289 | case xd.IsMap(): |
| 290 | isValid = v.Map().IsValid() |
| 291 | case xd.Message() != nil: |
| 292 | isValid = v.Message().IsValid() |
| 293 | } |
| 294 | if !isValid { |
| 295 | panic(fmt.Sprintf("%v: assigning invalid value", xt.TypeDescriptor().FullName())) |
| 296 | } |
| 297 | |
| 298 | if *m == nil { |
| 299 | *m = make(map[int32]ExtensionField) |
| 300 | } |
| 301 | var x ExtensionField |
| 302 | x.Set(xt, v) |
| 303 | (*m)[int32(xd.Number())] = x |
| 304 | } |
| 305 | func (m *extensionMap) Mutable(xt pref.ExtensionType) pref.Value { |
| 306 | xd := xt.TypeDescriptor() |
| 307 | if xd.Kind() != pref.MessageKind && xd.Kind() != pref.GroupKind && !xd.IsList() && !xd.IsMap() { |
| 308 | panic("invalid Mutable on field with non-composite type") |
| 309 | } |
| 310 | if x, ok := (*m)[int32(xd.Number())]; ok { |
| 311 | return x.Value() |
| 312 | } |
| 313 | v := xt.New() |
| 314 | m.Set(xt, v) |
| 315 | return v |
| 316 | } |
| 317 | |
| 318 | // MessageState is a data structure that is nested as the first field in a |
| 319 | // concrete message. It provides a way to implement the ProtoReflect method |
| 320 | // in an allocation-free way without needing to have a shadow Go type generated |
| 321 | // for every message type. This technique only works using unsafe. |
| 322 | // |
| 323 | // |
| 324 | // Example generated code: |
| 325 | // |
| 326 | // type M struct { |
| 327 | // state protoimpl.MessageState |
| 328 | // |
| 329 | // Field1 int32 |
| 330 | // Field2 string |
| 331 | // Field3 *BarMessage |
| 332 | // ... |
| 333 | // } |
| 334 | // |
| 335 | // func (m *M) ProtoReflect() protoreflect.Message { |
| 336 | // mi := &file_fizz_buzz_proto_msgInfos[5] |
| 337 | // if protoimpl.UnsafeEnabled && m != nil { |
| 338 | // ms := protoimpl.X.MessageStateOf(Pointer(m)) |
| 339 | // if ms.LoadMessageInfo() == nil { |
| 340 | // ms.StoreMessageInfo(mi) |
| 341 | // } |
| 342 | // return ms |
| 343 | // } |
| 344 | // return mi.MessageOf(m) |
| 345 | // } |
| 346 | // |
| 347 | // The MessageState type holds a *MessageInfo, which must be atomically set to |
| 348 | // the message info associated with a given message instance. |
| 349 | // By unsafely converting a *M into a *MessageState, the MessageState object |
| 350 | // has access to all the information needed to implement protobuf reflection. |
| 351 | // It has access to the message info as its first field, and a pointer to the |
| 352 | // MessageState is identical to a pointer to the concrete message value. |
| 353 | // |
| 354 | // |
| 355 | // Requirements: |
| 356 | // • The type M must implement protoreflect.ProtoMessage. |
| 357 | // • The address of m must not be nil. |
| 358 | // • The address of m and the address of m.state must be equal, |
| 359 | // even though they are different Go types. |
| 360 | type MessageState struct { |
| 361 | pragma.NoUnkeyedLiterals |
| 362 | pragma.DoNotCompare |
| 363 | pragma.DoNotCopy |
| 364 | |
| 365 | atomicMessageInfo *MessageInfo |
| 366 | } |
| 367 | |
| 368 | type messageState MessageState |
| 369 | |
| 370 | var ( |
| 371 | _ pref.Message = (*messageState)(nil) |
| 372 | _ unwrapper = (*messageState)(nil) |
| 373 | ) |
| 374 | |
| 375 | // messageDataType is a tuple of a pointer to the message data and |
| 376 | // a pointer to the message type. It is a generalized way of providing a |
| 377 | // reflective view over a message instance. The disadvantage of this approach |
| 378 | // is the need to allocate this tuple of 16B. |
| 379 | type messageDataType struct { |
| 380 | p pointer |
| 381 | mi *MessageInfo |
| 382 | } |
| 383 | |
| 384 | type ( |
| 385 | messageReflectWrapper messageDataType |
| 386 | messageIfaceWrapper messageDataType |
| 387 | ) |
| 388 | |
| 389 | var ( |
| 390 | _ pref.Message = (*messageReflectWrapper)(nil) |
| 391 | _ unwrapper = (*messageReflectWrapper)(nil) |
| 392 | _ pref.ProtoMessage = (*messageIfaceWrapper)(nil) |
| 393 | _ unwrapper = (*messageIfaceWrapper)(nil) |
| 394 | ) |
| 395 | |
| 396 | // MessageOf returns a reflective view over a message. The input must be a |
| 397 | // pointer to a named Go struct. If the provided type has a ProtoReflect method, |
| 398 | // it must be implemented by calling this method. |
| 399 | func (mi *MessageInfo) MessageOf(m interface{}) pref.Message { |
| 400 | if reflect.TypeOf(m) != mi.GoReflectType { |
| 401 | panic(fmt.Sprintf("type mismatch: got %T, want %v", m, mi.GoReflectType)) |
| 402 | } |
| 403 | p := pointerOfIface(m) |
| 404 | if p.IsNil() { |
| 405 | return mi.nilMessage.Init(mi) |
| 406 | } |
| 407 | return &messageReflectWrapper{p, mi} |
| 408 | } |
| 409 | |
| 410 | func (m *messageReflectWrapper) pointer() pointer { return m.p } |
| 411 | func (m *messageReflectWrapper) messageInfo() *MessageInfo { return m.mi } |
| 412 | |
| 413 | // Reset implements the v1 proto.Message.Reset method. |
| 414 | func (m *messageIfaceWrapper) Reset() { |
| 415 | if mr, ok := m.protoUnwrap().(interface{ Reset() }); ok { |
| 416 | mr.Reset() |
| 417 | return |
| 418 | } |
| 419 | rv := reflect.ValueOf(m.protoUnwrap()) |
| 420 | if rv.Kind() == reflect.Ptr && !rv.IsNil() { |
| 421 | rv.Elem().Set(reflect.Zero(rv.Type().Elem())) |
| 422 | } |
| 423 | } |
| 424 | func (m *messageIfaceWrapper) ProtoReflect() pref.Message { |
| 425 | return (*messageReflectWrapper)(m) |
| 426 | } |
| 427 | func (m *messageIfaceWrapper) protoUnwrap() interface{} { |
| 428 | return m.p.AsIfaceOf(m.mi.GoReflectType.Elem()) |
| 429 | } |
| 430 | |
| 431 | // checkField verifies that the provided field descriptor is valid. |
| 432 | // Exactly one of the returned values is populated. |
| 433 | func (mi *MessageInfo) checkField(fd pref.FieldDescriptor) (*fieldInfo, pref.ExtensionType) { |
| 434 | var fi *fieldInfo |
| 435 | if n := fd.Number(); 0 < n && int(n) < len(mi.denseFields) { |
| 436 | fi = mi.denseFields[n] |
| 437 | } else { |
| 438 | fi = mi.fields[n] |
| 439 | } |
| 440 | if fi != nil { |
| 441 | if fi.fieldDesc != fd { |
| 442 | if got, want := fd.FullName(), fi.fieldDesc.FullName(); got != want { |
| 443 | panic(fmt.Sprintf("mismatching field: got %v, want %v", got, want)) |
| 444 | } |
| 445 | panic(fmt.Sprintf("mismatching field: %v", fd.FullName())) |
| 446 | } |
| 447 | return fi, nil |
| 448 | } |
| 449 | |
| 450 | if fd.IsExtension() { |
| 451 | if got, want := fd.ContainingMessage().FullName(), mi.Desc.FullName(); got != want { |
| 452 | // TODO: Should this be exact containing message descriptor match? |
| 453 | panic(fmt.Sprintf("extension %v has mismatching containing message: got %v, want %v", fd.FullName(), got, want)) |
| 454 | } |
| 455 | if !mi.Desc.ExtensionRanges().Has(fd.Number()) { |
| 456 | panic(fmt.Sprintf("extension %v extends %v outside the extension range", fd.FullName(), mi.Desc.FullName())) |
| 457 | } |
| 458 | xtd, ok := fd.(pref.ExtensionTypeDescriptor) |
| 459 | if !ok { |
| 460 | panic(fmt.Sprintf("extension %v does not implement protoreflect.ExtensionTypeDescriptor", fd.FullName())) |
| 461 | } |
| 462 | return nil, xtd.Type() |
| 463 | } |
| 464 | panic(fmt.Sprintf("field %v is invalid", fd.FullName())) |
| 465 | } |