Scott Baker | e7144bc | 2019-10-01 14:16:47 -0700 | [diff] [blame^] | 1 | // Go support for Protocol Buffers - Google's data interchange format |
| 2 | // |
| 3 | // Copyright 2010 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 | package proto |
| 33 | |
| 34 | /* |
| 35 | * Types and routines for supporting protocol buffer extensions. |
| 36 | */ |
| 37 | |
| 38 | import ( |
| 39 | "errors" |
| 40 | "fmt" |
| 41 | "io" |
| 42 | "reflect" |
| 43 | "strconv" |
| 44 | "sync" |
| 45 | ) |
| 46 | |
| 47 | // ErrMissingExtension is the error returned by GetExtension if the named extension is not in the message. |
| 48 | var ErrMissingExtension = errors.New("proto: missing extension") |
| 49 | |
| 50 | // ExtensionRange represents a range of message extensions for a protocol buffer. |
| 51 | // Used in code generated by the protocol compiler. |
| 52 | type ExtensionRange struct { |
| 53 | Start, End int32 // both inclusive |
| 54 | } |
| 55 | |
| 56 | // extendableProto is an interface implemented by any protocol buffer generated by the current |
| 57 | // proto compiler that may be extended. |
| 58 | type extendableProto interface { |
| 59 | Message |
| 60 | ExtensionRangeArray() []ExtensionRange |
| 61 | extensionsWrite() map[int32]Extension |
| 62 | extensionsRead() (map[int32]Extension, sync.Locker) |
| 63 | } |
| 64 | |
| 65 | // extendableProtoV1 is an interface implemented by a protocol buffer generated by the previous |
| 66 | // version of the proto compiler that may be extended. |
| 67 | type extendableProtoV1 interface { |
| 68 | Message |
| 69 | ExtensionRangeArray() []ExtensionRange |
| 70 | ExtensionMap() map[int32]Extension |
| 71 | } |
| 72 | |
| 73 | // extensionAdapter is a wrapper around extendableProtoV1 that implements extendableProto. |
| 74 | type extensionAdapter struct { |
| 75 | extendableProtoV1 |
| 76 | } |
| 77 | |
| 78 | func (e extensionAdapter) extensionsWrite() map[int32]Extension { |
| 79 | return e.ExtensionMap() |
| 80 | } |
| 81 | |
| 82 | func (e extensionAdapter) extensionsRead() (map[int32]Extension, sync.Locker) { |
| 83 | return e.ExtensionMap(), notLocker{} |
| 84 | } |
| 85 | |
| 86 | // notLocker is a sync.Locker whose Lock and Unlock methods are nops. |
| 87 | type notLocker struct{} |
| 88 | |
| 89 | func (n notLocker) Lock() {} |
| 90 | func (n notLocker) Unlock() {} |
| 91 | |
| 92 | // extendable returns the extendableProto interface for the given generated proto message. |
| 93 | // If the proto message has the old extension format, it returns a wrapper that implements |
| 94 | // the extendableProto interface. |
| 95 | func extendable(p interface{}) (extendableProto, error) { |
| 96 | switch p := p.(type) { |
| 97 | case extendableProto: |
| 98 | if isNilPtr(p) { |
| 99 | return nil, fmt.Errorf("proto: nil %T is not extendable", p) |
| 100 | } |
| 101 | return p, nil |
| 102 | case extendableProtoV1: |
| 103 | if isNilPtr(p) { |
| 104 | return nil, fmt.Errorf("proto: nil %T is not extendable", p) |
| 105 | } |
| 106 | return extensionAdapter{p}, nil |
| 107 | case extensionsBytes: |
| 108 | return slowExtensionAdapter{p}, nil |
| 109 | } |
| 110 | // Don't allocate a specific error containing %T: |
| 111 | // this is the hot path for Clone and MarshalText. |
| 112 | return nil, errNotExtendable |
| 113 | } |
| 114 | |
| 115 | var errNotExtendable = errors.New("proto: not an extendable proto.Message") |
| 116 | |
| 117 | func isNilPtr(x interface{}) bool { |
| 118 | v := reflect.ValueOf(x) |
| 119 | return v.Kind() == reflect.Ptr && v.IsNil() |
| 120 | } |
| 121 | |
| 122 | // XXX_InternalExtensions is an internal representation of proto extensions. |
| 123 | // |
| 124 | // Each generated message struct type embeds an anonymous XXX_InternalExtensions field, |
| 125 | // thus gaining the unexported 'extensions' method, which can be called only from the proto package. |
| 126 | // |
| 127 | // The methods of XXX_InternalExtensions are not concurrency safe in general, |
| 128 | // but calls to logically read-only methods such as has and get may be executed concurrently. |
| 129 | type XXX_InternalExtensions struct { |
| 130 | // The struct must be indirect so that if a user inadvertently copies a |
| 131 | // generated message and its embedded XXX_InternalExtensions, they |
| 132 | // avoid the mayhem of a copied mutex. |
| 133 | // |
| 134 | // The mutex serializes all logically read-only operations to p.extensionMap. |
| 135 | // It is up to the client to ensure that write operations to p.extensionMap are |
| 136 | // mutually exclusive with other accesses. |
| 137 | p *struct { |
| 138 | mu sync.Mutex |
| 139 | extensionMap map[int32]Extension |
| 140 | } |
| 141 | } |
| 142 | |
| 143 | // extensionsWrite returns the extension map, creating it on first use. |
| 144 | func (e *XXX_InternalExtensions) extensionsWrite() map[int32]Extension { |
| 145 | if e.p == nil { |
| 146 | e.p = new(struct { |
| 147 | mu sync.Mutex |
| 148 | extensionMap map[int32]Extension |
| 149 | }) |
| 150 | e.p.extensionMap = make(map[int32]Extension) |
| 151 | } |
| 152 | return e.p.extensionMap |
| 153 | } |
| 154 | |
| 155 | // extensionsRead returns the extensions map for read-only use. It may be nil. |
| 156 | // The caller must hold the returned mutex's lock when accessing Elements within the map. |
| 157 | func (e *XXX_InternalExtensions) extensionsRead() (map[int32]Extension, sync.Locker) { |
| 158 | if e.p == nil { |
| 159 | return nil, nil |
| 160 | } |
| 161 | return e.p.extensionMap, &e.p.mu |
| 162 | } |
| 163 | |
| 164 | // ExtensionDesc represents an extension specification. |
| 165 | // Used in generated code from the protocol compiler. |
| 166 | type ExtensionDesc struct { |
| 167 | ExtendedType Message // nil pointer to the type that is being extended |
| 168 | ExtensionType interface{} // nil pointer to the extension type |
| 169 | Field int32 // field number |
| 170 | Name string // fully-qualified name of extension, for text formatting |
| 171 | Tag string // protobuf tag style |
| 172 | Filename string // name of the file in which the extension is defined |
| 173 | } |
| 174 | |
| 175 | func (ed *ExtensionDesc) repeated() bool { |
| 176 | t := reflect.TypeOf(ed.ExtensionType) |
| 177 | return t.Kind() == reflect.Slice && t.Elem().Kind() != reflect.Uint8 |
| 178 | } |
| 179 | |
| 180 | // Extension represents an extension in a message. |
| 181 | type Extension struct { |
| 182 | // When an extension is stored in a message using SetExtension |
| 183 | // only desc and value are set. When the message is marshaled |
| 184 | // enc will be set to the encoded form of the message. |
| 185 | // |
| 186 | // When a message is unmarshaled and contains extensions, each |
| 187 | // extension will have only enc set. When such an extension is |
| 188 | // accessed using GetExtension (or GetExtensions) desc and value |
| 189 | // will be set. |
| 190 | desc *ExtensionDesc |
| 191 | value interface{} |
| 192 | enc []byte |
| 193 | } |
| 194 | |
| 195 | // SetRawExtension is for testing only. |
| 196 | func SetRawExtension(base Message, id int32, b []byte) { |
| 197 | if ebase, ok := base.(extensionsBytes); ok { |
| 198 | clearExtension(base, id) |
| 199 | ext := ebase.GetExtensions() |
| 200 | *ext = append(*ext, b...) |
| 201 | return |
| 202 | } |
| 203 | epb, err := extendable(base) |
| 204 | if err != nil { |
| 205 | return |
| 206 | } |
| 207 | extmap := epb.extensionsWrite() |
| 208 | extmap[id] = Extension{enc: b} |
| 209 | } |
| 210 | |
| 211 | // isExtensionField returns true iff the given field number is in an extension range. |
| 212 | func isExtensionField(pb extendableProto, field int32) bool { |
| 213 | for _, er := range pb.ExtensionRangeArray() { |
| 214 | if er.Start <= field && field <= er.End { |
| 215 | return true |
| 216 | } |
| 217 | } |
| 218 | return false |
| 219 | } |
| 220 | |
| 221 | // checkExtensionTypes checks that the given extension is valid for pb. |
| 222 | func checkExtensionTypes(pb extendableProto, extension *ExtensionDesc) error { |
| 223 | var pbi interface{} = pb |
| 224 | // Check the extended type. |
| 225 | if ea, ok := pbi.(extensionAdapter); ok { |
| 226 | pbi = ea.extendableProtoV1 |
| 227 | } |
| 228 | if ea, ok := pbi.(slowExtensionAdapter); ok { |
| 229 | pbi = ea.extensionsBytes |
| 230 | } |
| 231 | if a, b := reflect.TypeOf(pbi), reflect.TypeOf(extension.ExtendedType); a != b { |
| 232 | return fmt.Errorf("proto: bad extended type; %v does not extend %v", b, a) |
| 233 | } |
| 234 | // Check the range. |
| 235 | if !isExtensionField(pb, extension.Field) { |
| 236 | return errors.New("proto: bad extension number; not in declared ranges") |
| 237 | } |
| 238 | return nil |
| 239 | } |
| 240 | |
| 241 | // extPropKey is sufficient to uniquely identify an extension. |
| 242 | type extPropKey struct { |
| 243 | base reflect.Type |
| 244 | field int32 |
| 245 | } |
| 246 | |
| 247 | var extProp = struct { |
| 248 | sync.RWMutex |
| 249 | m map[extPropKey]*Properties |
| 250 | }{ |
| 251 | m: make(map[extPropKey]*Properties), |
| 252 | } |
| 253 | |
| 254 | func extensionProperties(ed *ExtensionDesc) *Properties { |
| 255 | key := extPropKey{base: reflect.TypeOf(ed.ExtendedType), field: ed.Field} |
| 256 | |
| 257 | extProp.RLock() |
| 258 | if prop, ok := extProp.m[key]; ok { |
| 259 | extProp.RUnlock() |
| 260 | return prop |
| 261 | } |
| 262 | extProp.RUnlock() |
| 263 | |
| 264 | extProp.Lock() |
| 265 | defer extProp.Unlock() |
| 266 | // Check again. |
| 267 | if prop, ok := extProp.m[key]; ok { |
| 268 | return prop |
| 269 | } |
| 270 | |
| 271 | prop := new(Properties) |
| 272 | prop.Init(reflect.TypeOf(ed.ExtensionType), "unknown_name", ed.Tag, nil) |
| 273 | extProp.m[key] = prop |
| 274 | return prop |
| 275 | } |
| 276 | |
| 277 | // HasExtension returns whether the given extension is present in pb. |
| 278 | func HasExtension(pb Message, extension *ExtensionDesc) bool { |
| 279 | if epb, doki := pb.(extensionsBytes); doki { |
| 280 | ext := epb.GetExtensions() |
| 281 | buf := *ext |
| 282 | o := 0 |
| 283 | for o < len(buf) { |
| 284 | tag, n := DecodeVarint(buf[o:]) |
| 285 | fieldNum := int32(tag >> 3) |
| 286 | if int32(fieldNum) == extension.Field { |
| 287 | return true |
| 288 | } |
| 289 | wireType := int(tag & 0x7) |
| 290 | o += n |
| 291 | l, err := size(buf[o:], wireType) |
| 292 | if err != nil { |
| 293 | return false |
| 294 | } |
| 295 | o += l |
| 296 | } |
| 297 | return false |
| 298 | } |
| 299 | // TODO: Check types, field numbers, etc.? |
| 300 | epb, err := extendable(pb) |
| 301 | if err != nil { |
| 302 | return false |
| 303 | } |
| 304 | extmap, mu := epb.extensionsRead() |
| 305 | if extmap == nil { |
| 306 | return false |
| 307 | } |
| 308 | mu.Lock() |
| 309 | _, ok := extmap[extension.Field] |
| 310 | mu.Unlock() |
| 311 | return ok |
| 312 | } |
| 313 | |
| 314 | // ClearExtension removes the given extension from pb. |
| 315 | func ClearExtension(pb Message, extension *ExtensionDesc) { |
| 316 | clearExtension(pb, extension.Field) |
| 317 | } |
| 318 | |
| 319 | func clearExtension(pb Message, fieldNum int32) { |
| 320 | if epb, ok := pb.(extensionsBytes); ok { |
| 321 | offset := 0 |
| 322 | for offset != -1 { |
| 323 | offset = deleteExtension(epb, fieldNum, offset) |
| 324 | } |
| 325 | return |
| 326 | } |
| 327 | epb, err := extendable(pb) |
| 328 | if err != nil { |
| 329 | return |
| 330 | } |
| 331 | // TODO: Check types, field numbers, etc.? |
| 332 | extmap := epb.extensionsWrite() |
| 333 | delete(extmap, fieldNum) |
| 334 | } |
| 335 | |
| 336 | // GetExtension retrieves a proto2 extended field from pb. |
| 337 | // |
| 338 | // If the descriptor is type complete (i.e., ExtensionDesc.ExtensionType is non-nil), |
| 339 | // then GetExtension parses the encoded field and returns a Go value of the specified type. |
| 340 | // If the field is not present, then the default value is returned (if one is specified), |
| 341 | // otherwise ErrMissingExtension is reported. |
| 342 | // |
| 343 | // If the descriptor is not type complete (i.e., ExtensionDesc.ExtensionType is nil), |
| 344 | // then GetExtension returns the raw encoded bytes of the field extension. |
| 345 | func GetExtension(pb Message, extension *ExtensionDesc) (interface{}, error) { |
| 346 | if epb, doki := pb.(extensionsBytes); doki { |
| 347 | ext := epb.GetExtensions() |
| 348 | return decodeExtensionFromBytes(extension, *ext) |
| 349 | } |
| 350 | |
| 351 | epb, err := extendable(pb) |
| 352 | if err != nil { |
| 353 | return nil, err |
| 354 | } |
| 355 | |
| 356 | if extension.ExtendedType != nil { |
| 357 | // can only check type if this is a complete descriptor |
| 358 | if cerr := checkExtensionTypes(epb, extension); cerr != nil { |
| 359 | return nil, cerr |
| 360 | } |
| 361 | } |
| 362 | |
| 363 | emap, mu := epb.extensionsRead() |
| 364 | if emap == nil { |
| 365 | return defaultExtensionValue(extension) |
| 366 | } |
| 367 | mu.Lock() |
| 368 | defer mu.Unlock() |
| 369 | e, ok := emap[extension.Field] |
| 370 | if !ok { |
| 371 | // defaultExtensionValue returns the default value or |
| 372 | // ErrMissingExtension if there is no default. |
| 373 | return defaultExtensionValue(extension) |
| 374 | } |
| 375 | |
| 376 | if e.value != nil { |
| 377 | // Already decoded. Check the descriptor, though. |
| 378 | if e.desc != extension { |
| 379 | // This shouldn't happen. If it does, it means that |
| 380 | // GetExtension was called twice with two different |
| 381 | // descriptors with the same field number. |
| 382 | return nil, errors.New("proto: descriptor conflict") |
| 383 | } |
| 384 | return e.value, nil |
| 385 | } |
| 386 | |
| 387 | if extension.ExtensionType == nil { |
| 388 | // incomplete descriptor |
| 389 | return e.enc, nil |
| 390 | } |
| 391 | |
| 392 | v, err := decodeExtension(e.enc, extension) |
| 393 | if err != nil { |
| 394 | return nil, err |
| 395 | } |
| 396 | |
| 397 | // Remember the decoded version and drop the encoded version. |
| 398 | // That way it is safe to mutate what we return. |
| 399 | e.value = v |
| 400 | e.desc = extension |
| 401 | e.enc = nil |
| 402 | emap[extension.Field] = e |
| 403 | return e.value, nil |
| 404 | } |
| 405 | |
| 406 | // defaultExtensionValue returns the default value for extension. |
| 407 | // If no default for an extension is defined ErrMissingExtension is returned. |
| 408 | func defaultExtensionValue(extension *ExtensionDesc) (interface{}, error) { |
| 409 | if extension.ExtensionType == nil { |
| 410 | // incomplete descriptor, so no default |
| 411 | return nil, ErrMissingExtension |
| 412 | } |
| 413 | |
| 414 | t := reflect.TypeOf(extension.ExtensionType) |
| 415 | props := extensionProperties(extension) |
| 416 | |
| 417 | sf, _, err := fieldDefault(t, props) |
| 418 | if err != nil { |
| 419 | return nil, err |
| 420 | } |
| 421 | |
| 422 | if sf == nil || sf.value == nil { |
| 423 | // There is no default value. |
| 424 | return nil, ErrMissingExtension |
| 425 | } |
| 426 | |
| 427 | if t.Kind() != reflect.Ptr { |
| 428 | // We do not need to return a Ptr, we can directly return sf.value. |
| 429 | return sf.value, nil |
| 430 | } |
| 431 | |
| 432 | // We need to return an interface{} that is a pointer to sf.value. |
| 433 | value := reflect.New(t).Elem() |
| 434 | value.Set(reflect.New(value.Type().Elem())) |
| 435 | if sf.kind == reflect.Int32 { |
| 436 | // We may have an int32 or an enum, but the underlying data is int32. |
| 437 | // Since we can't set an int32 into a non int32 reflect.value directly |
| 438 | // set it as a int32. |
| 439 | value.Elem().SetInt(int64(sf.value.(int32))) |
| 440 | } else { |
| 441 | value.Elem().Set(reflect.ValueOf(sf.value)) |
| 442 | } |
| 443 | return value.Interface(), nil |
| 444 | } |
| 445 | |
| 446 | // decodeExtension decodes an extension encoded in b. |
| 447 | func decodeExtension(b []byte, extension *ExtensionDesc) (interface{}, error) { |
| 448 | t := reflect.TypeOf(extension.ExtensionType) |
| 449 | unmarshal := typeUnmarshaler(t, extension.Tag) |
| 450 | |
| 451 | // t is a pointer to a struct, pointer to basic type or a slice. |
| 452 | // Allocate space to store the pointer/slice. |
| 453 | value := reflect.New(t).Elem() |
| 454 | |
| 455 | var err error |
| 456 | for { |
| 457 | x, n := decodeVarint(b) |
| 458 | if n == 0 { |
| 459 | return nil, io.ErrUnexpectedEOF |
| 460 | } |
| 461 | b = b[n:] |
| 462 | wire := int(x) & 7 |
| 463 | |
| 464 | b, err = unmarshal(b, valToPointer(value.Addr()), wire) |
| 465 | if err != nil { |
| 466 | return nil, err |
| 467 | } |
| 468 | |
| 469 | if len(b) == 0 { |
| 470 | break |
| 471 | } |
| 472 | } |
| 473 | return value.Interface(), nil |
| 474 | } |
| 475 | |
| 476 | // GetExtensions returns a slice of the extensions present in pb that are also listed in es. |
| 477 | // The returned slice has the same length as es; missing extensions will appear as nil elements. |
| 478 | func GetExtensions(pb Message, es []*ExtensionDesc) (extensions []interface{}, err error) { |
| 479 | epb, err := extendable(pb) |
| 480 | if err != nil { |
| 481 | return nil, err |
| 482 | } |
| 483 | extensions = make([]interface{}, len(es)) |
| 484 | for i, e := range es { |
| 485 | extensions[i], err = GetExtension(epb, e) |
| 486 | if err == ErrMissingExtension { |
| 487 | err = nil |
| 488 | } |
| 489 | if err != nil { |
| 490 | return |
| 491 | } |
| 492 | } |
| 493 | return |
| 494 | } |
| 495 | |
| 496 | // ExtensionDescs returns a new slice containing pb's extension descriptors, in undefined order. |
| 497 | // For non-registered extensions, ExtensionDescs returns an incomplete descriptor containing |
| 498 | // just the Field field, which defines the extension's field number. |
| 499 | func ExtensionDescs(pb Message) ([]*ExtensionDesc, error) { |
| 500 | epb, err := extendable(pb) |
| 501 | if err != nil { |
| 502 | return nil, err |
| 503 | } |
| 504 | registeredExtensions := RegisteredExtensions(pb) |
| 505 | |
| 506 | emap, mu := epb.extensionsRead() |
| 507 | if emap == nil { |
| 508 | return nil, nil |
| 509 | } |
| 510 | mu.Lock() |
| 511 | defer mu.Unlock() |
| 512 | extensions := make([]*ExtensionDesc, 0, len(emap)) |
| 513 | for extid, e := range emap { |
| 514 | desc := e.desc |
| 515 | if desc == nil { |
| 516 | desc = registeredExtensions[extid] |
| 517 | if desc == nil { |
| 518 | desc = &ExtensionDesc{Field: extid} |
| 519 | } |
| 520 | } |
| 521 | |
| 522 | extensions = append(extensions, desc) |
| 523 | } |
| 524 | return extensions, nil |
| 525 | } |
| 526 | |
| 527 | // SetExtension sets the specified extension of pb to the specified value. |
| 528 | func SetExtension(pb Message, extension *ExtensionDesc, value interface{}) error { |
| 529 | if epb, ok := pb.(extensionsBytes); ok { |
| 530 | newb, err := encodeExtension(extension, value) |
| 531 | if err != nil { |
| 532 | return err |
| 533 | } |
| 534 | bb := epb.GetExtensions() |
| 535 | *bb = append(*bb, newb...) |
| 536 | return nil |
| 537 | } |
| 538 | epb, err := extendable(pb) |
| 539 | if err != nil { |
| 540 | return err |
| 541 | } |
| 542 | if err := checkExtensionTypes(epb, extension); err != nil { |
| 543 | return err |
| 544 | } |
| 545 | typ := reflect.TypeOf(extension.ExtensionType) |
| 546 | if typ != reflect.TypeOf(value) { |
| 547 | return fmt.Errorf("proto: bad extension value type. got: %T, want: %T", value, extension.ExtensionType) |
| 548 | } |
| 549 | // nil extension values need to be caught early, because the |
| 550 | // encoder can't distinguish an ErrNil due to a nil extension |
| 551 | // from an ErrNil due to a missing field. Extensions are |
| 552 | // always optional, so the encoder would just swallow the error |
| 553 | // and drop all the extensions from the encoded message. |
| 554 | if reflect.ValueOf(value).IsNil() { |
| 555 | return fmt.Errorf("proto: SetExtension called with nil value of type %T", value) |
| 556 | } |
| 557 | |
| 558 | extmap := epb.extensionsWrite() |
| 559 | extmap[extension.Field] = Extension{desc: extension, value: value} |
| 560 | return nil |
| 561 | } |
| 562 | |
| 563 | // ClearAllExtensions clears all extensions from pb. |
| 564 | func ClearAllExtensions(pb Message) { |
| 565 | if epb, doki := pb.(extensionsBytes); doki { |
| 566 | ext := epb.GetExtensions() |
| 567 | *ext = []byte{} |
| 568 | return |
| 569 | } |
| 570 | epb, err := extendable(pb) |
| 571 | if err != nil { |
| 572 | return |
| 573 | } |
| 574 | m := epb.extensionsWrite() |
| 575 | for k := range m { |
| 576 | delete(m, k) |
| 577 | } |
| 578 | } |
| 579 | |
| 580 | // A global registry of extensions. |
| 581 | // The generated code will register the generated descriptors by calling RegisterExtension. |
| 582 | |
| 583 | var extensionMaps = make(map[reflect.Type]map[int32]*ExtensionDesc) |
| 584 | |
| 585 | // RegisterExtension is called from the generated code. |
| 586 | func RegisterExtension(desc *ExtensionDesc) { |
| 587 | st := reflect.TypeOf(desc.ExtendedType).Elem() |
| 588 | m := extensionMaps[st] |
| 589 | if m == nil { |
| 590 | m = make(map[int32]*ExtensionDesc) |
| 591 | extensionMaps[st] = m |
| 592 | } |
| 593 | if _, ok := m[desc.Field]; ok { |
| 594 | panic("proto: duplicate extension registered: " + st.String() + " " + strconv.Itoa(int(desc.Field))) |
| 595 | } |
| 596 | m[desc.Field] = desc |
| 597 | } |
| 598 | |
| 599 | // RegisteredExtensions returns a map of the registered extensions of a |
| 600 | // protocol buffer struct, indexed by the extension number. |
| 601 | // The argument pb should be a nil pointer to the struct type. |
| 602 | func RegisteredExtensions(pb Message) map[int32]*ExtensionDesc { |
| 603 | return extensionMaps[reflect.TypeOf(pb).Elem()] |
| 604 | } |