mirror of
https://github.com/protocolbuffers/protobuf-go.git
synced 2025-02-12 00:40:00 +00:00
47d5893acf
Support, to some limited degree, types which implement protoV1.Message but which are not struct pointers. Our ability to work with these types is largely limited to calling Marshal or Unmarshal methods, when present. Change-Id: Ie1b851d9e753e2b2cb189b17ffeefebe2d8b3a8f Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/198237 Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
441 lines
14 KiB
Go
441 lines
14 KiB
Go
// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package impl
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import (
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"fmt"
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"reflect"
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"strings"
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"sync"
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"google.golang.org/protobuf/internal/descopts"
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ptag "google.golang.org/protobuf/internal/encoding/tag"
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"google.golang.org/protobuf/internal/errors"
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"google.golang.org/protobuf/internal/filedesc"
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"google.golang.org/protobuf/internal/strs"
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"google.golang.org/protobuf/reflect/protoreflect"
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pref "google.golang.org/protobuf/reflect/protoreflect"
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piface "google.golang.org/protobuf/runtime/protoiface"
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)
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// legacyWrapMessage wraps v as a protoreflect.ProtoMessage,
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// where v must be a *struct kind and not implement the v2 API already.
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func legacyWrapMessage(v reflect.Value) pref.ProtoMessage {
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typ := v.Type()
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if typ.Kind() != reflect.Ptr || typ.Elem().Kind() != reflect.Struct {
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return aberrantMessage{v: v}
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}
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mt := legacyLoadMessageInfo(typ, "")
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return mt.MessageOf(v.Interface()).Interface()
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}
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var legacyMessageTypeCache sync.Map // map[reflect.Type]*MessageInfo
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// legacyLoadMessageInfo dynamically loads a *MessageInfo for t,
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// where t must be a *struct kind and not implement the v2 API already.
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// The provided name is used if it cannot be determined from the message.
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func legacyLoadMessageInfo(t reflect.Type, name pref.FullName) *MessageInfo {
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// Fast-path: check if a MessageInfo is cached for this concrete type.
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if mt, ok := legacyMessageTypeCache.Load(t); ok {
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return mt.(*MessageInfo)
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}
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// Slow-path: derive message descriptor and initialize MessageInfo.
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mi := &MessageInfo{
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Desc: legacyLoadMessageDesc(t, name),
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GoReflectType: t,
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}
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v := reflect.Zero(t).Interface()
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if _, ok := v.(legacyMarshaler); ok {
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mi.methods.MarshalAppend = legacyMarshalAppend
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mi.methods.Size = legacySize
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}
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if _, ok := v.(legacyUnmarshaler); ok {
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mi.methods.Unmarshal = legacyUnmarshal
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}
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if mi, ok := legacyMessageTypeCache.LoadOrStore(t, mi); ok {
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return mi.(*MessageInfo)
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}
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return mi
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}
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var legacyMessageDescCache sync.Map // map[reflect.Type]protoreflect.MessageDescriptor
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// LegacyLoadMessageDesc returns an MessageDescriptor derived from the Go type,
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// which must be a *struct kind and not implement the v2 API already.
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//
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// This is exported for testing purposes.
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func LegacyLoadMessageDesc(t reflect.Type) pref.MessageDescriptor {
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return legacyLoadMessageDesc(t, "")
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}
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func legacyLoadMessageDesc(t reflect.Type, name pref.FullName) pref.MessageDescriptor {
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// Fast-path: check if a MessageDescriptor is cached for this concrete type.
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if mi, ok := legacyMessageDescCache.Load(t); ok {
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return mi.(pref.MessageDescriptor)
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}
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// Slow-path: initialize MessageDescriptor from the raw descriptor.
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mv := reflect.Zero(t).Interface()
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if _, ok := mv.(pref.ProtoMessage); ok {
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panic(fmt.Sprintf("%v already implements proto.Message", t))
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}
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mdV1, ok := mv.(messageV1)
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if !ok {
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return aberrantLoadMessageDesc(t, name)
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}
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b, idxs := mdV1.Descriptor()
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md := legacyLoadFileDesc(b).Messages().Get(idxs[0])
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for _, i := range idxs[1:] {
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md = md.Messages().Get(i)
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}
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if name != "" && md.FullName() != name {
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panic(fmt.Sprintf("mismatching message name: got %v, want %v", md.FullName(), name))
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}
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if md, ok := legacyMessageDescCache.LoadOrStore(t, md); ok {
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return md.(protoreflect.MessageDescriptor)
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}
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return md
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}
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var (
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aberrantMessageDescLock sync.Mutex
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aberrantMessageDescCache map[reflect.Type]protoreflect.MessageDescriptor
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)
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// aberrantLoadMessageDesc returns an MessageDescriptor derived from the Go type,
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// which must not implement protoreflect.ProtoMessage or messageV1.
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//
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// This is a best-effort derivation of the message descriptor using the protobuf
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// tags on the struct fields.
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func aberrantLoadMessageDesc(t reflect.Type, name pref.FullName) pref.MessageDescriptor {
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aberrantMessageDescLock.Lock()
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defer aberrantMessageDescLock.Unlock()
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if aberrantMessageDescCache == nil {
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aberrantMessageDescCache = make(map[reflect.Type]protoreflect.MessageDescriptor)
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}
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return aberrantLoadMessageDescReentrant(t, name)
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}
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func aberrantLoadMessageDescReentrant(t reflect.Type, name pref.FullName) pref.MessageDescriptor {
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// Fast-path: check if an MessageDescriptor is cached for this concrete type.
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if md, ok := aberrantMessageDescCache[t]; ok {
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return md
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}
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// Slow-path: construct a descriptor from the Go struct type (best-effort).
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// Cache the MessageDescriptor early on so that we can resolve internal
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// cyclic references.
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md := &filedesc.Message{L2: new(filedesc.MessageL2)}
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md.L0.FullName = aberrantDeriveMessageName(t, name)
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md.L0.ParentFile = filedesc.SurrogateProto2
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aberrantMessageDescCache[t] = md
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if t.Kind() != reflect.Ptr || t.Elem().Kind() != reflect.Struct {
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return md
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}
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// Try to determine if the message is using proto3 by checking scalars.
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for i := 0; i < t.Elem().NumField(); i++ {
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f := t.Elem().Field(i)
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if tag := f.Tag.Get("protobuf"); tag != "" {
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switch f.Type.Kind() {
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case reflect.Bool, reflect.Int32, reflect.Int64, reflect.Uint32, reflect.Uint64, reflect.Float32, reflect.Float64, reflect.String:
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md.L0.ParentFile = filedesc.SurrogateProto3
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}
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for _, s := range strings.Split(tag, ",") {
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if s == "proto3" {
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md.L0.ParentFile = filedesc.SurrogateProto3
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}
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}
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}
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}
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// Obtain a list of oneof wrapper types.
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var oneofWrappers []reflect.Type
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if fn, ok := t.MethodByName("XXX_OneofFuncs"); ok {
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vs := fn.Func.Call([]reflect.Value{reflect.Zero(fn.Type.In(0))})[3]
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for _, v := range vs.Interface().([]interface{}) {
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oneofWrappers = append(oneofWrappers, reflect.TypeOf(v))
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}
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}
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if fn, ok := t.MethodByName("XXX_OneofWrappers"); ok {
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vs := fn.Func.Call([]reflect.Value{reflect.Zero(fn.Type.In(0))})[0]
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for _, v := range vs.Interface().([]interface{}) {
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oneofWrappers = append(oneofWrappers, reflect.TypeOf(v))
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}
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}
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// Obtain a list of the extension ranges.
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if fn, ok := t.MethodByName("ExtensionRangeArray"); ok {
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vs := fn.Func.Call([]reflect.Value{reflect.Zero(fn.Type.In(0))})[0]
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for i := 0; i < vs.Len(); i++ {
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v := vs.Index(i)
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md.L2.ExtensionRanges.List = append(md.L2.ExtensionRanges.List, [2]pref.FieldNumber{
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pref.FieldNumber(v.FieldByName("Start").Int()),
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pref.FieldNumber(v.FieldByName("End").Int() + 1),
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})
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md.L2.ExtensionRangeOptions = append(md.L2.ExtensionRangeOptions, nil)
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}
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}
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// Derive the message fields by inspecting the struct fields.
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for i := 0; i < t.Elem().NumField(); i++ {
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f := t.Elem().Field(i)
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if tag := f.Tag.Get("protobuf"); tag != "" {
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tagKey := f.Tag.Get("protobuf_key")
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tagVal := f.Tag.Get("protobuf_val")
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aberrantAppendField(md, f.Type, tag, tagKey, tagVal)
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}
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if tag := f.Tag.Get("protobuf_oneof"); tag != "" {
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n := len(md.L2.Oneofs.List)
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md.L2.Oneofs.List = append(md.L2.Oneofs.List, filedesc.Oneof{})
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od := &md.L2.Oneofs.List[n]
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od.L0.FullName = md.FullName().Append(pref.Name(tag))
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od.L0.ParentFile = md.L0.ParentFile
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od.L0.Parent = md
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od.L0.Index = n
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for _, t := range oneofWrappers {
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if t.Implements(f.Type) {
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f := t.Elem().Field(0)
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if tag := f.Tag.Get("protobuf"); tag != "" {
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aberrantAppendField(md, f.Type, tag, "", "")
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fd := &md.L2.Fields.List[len(md.L2.Fields.List)-1]
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fd.L1.ContainingOneof = od
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od.L1.Fields.List = append(od.L1.Fields.List, fd)
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}
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}
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}
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}
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}
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return md
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}
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func aberrantDeriveMessageName(t reflect.Type, name pref.FullName) pref.FullName {
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if name.IsValid() {
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return name
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}
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func() {
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defer func() { recover() }() // swallow possible nil panics
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if m, ok := reflect.Zero(t).Interface().(interface{ XXX_MessageName() string }); ok {
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name = pref.FullName(m.XXX_MessageName())
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}
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}()
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if name.IsValid() {
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return name
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}
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if t.Kind() == reflect.Ptr {
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t = t.Elem()
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}
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return aberrantDeriveFullName(t)
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}
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func aberrantAppendField(md *filedesc.Message, goType reflect.Type, tag, tagKey, tagVal string) {
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t := goType
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isOptional := t.Kind() == reflect.Ptr && t.Elem().Kind() != reflect.Struct
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isRepeated := t.Kind() == reflect.Slice && t.Elem().Kind() != reflect.Uint8
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if isOptional || isRepeated {
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t = t.Elem()
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}
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fd := ptag.Unmarshal(tag, t, placeholderEnumValues{}).(*filedesc.Field)
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// Append field descriptor to the message.
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n := len(md.L2.Fields.List)
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md.L2.Fields.List = append(md.L2.Fields.List, *fd)
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fd = &md.L2.Fields.List[n]
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fd.L0.FullName = md.FullName().Append(fd.Name())
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fd.L0.ParentFile = md.L0.ParentFile
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fd.L0.Parent = md
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fd.L0.Index = n
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if fd.L1.IsWeak || fd.L1.HasPacked {
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fd.L1.Options = func() pref.ProtoMessage {
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opts := descopts.Field.ProtoReflect().New()
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if fd.L1.IsWeak {
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opts.Set(opts.Descriptor().Fields().ByName("weak"), protoreflect.ValueOfBool(true))
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}
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if fd.L1.HasPacked {
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opts.Set(opts.Descriptor().Fields().ByName("packed"), protoreflect.ValueOfBool(fd.L1.IsPacked))
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}
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return opts.Interface()
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}
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}
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// Populate Enum and Message.
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if fd.Enum() == nil && fd.Kind() == pref.EnumKind {
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switch v := reflect.Zero(t).Interface().(type) {
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case pref.Enum:
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fd.L1.Enum = v.Descriptor()
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default:
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fd.L1.Enum = LegacyLoadEnumDesc(t)
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}
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}
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if fd.Message() == nil && (fd.Kind() == pref.MessageKind || fd.Kind() == pref.GroupKind) {
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switch v := reflect.Zero(t).Interface().(type) {
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case pref.ProtoMessage:
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fd.L1.Message = v.ProtoReflect().Descriptor()
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case messageV1:
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fd.L1.Message = LegacyLoadMessageDesc(t)
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default:
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if t.Kind() == reflect.Map {
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n := len(md.L1.Messages.List)
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md.L1.Messages.List = append(md.L1.Messages.List, filedesc.Message{L2: new(filedesc.MessageL2)})
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md2 := &md.L1.Messages.List[n]
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md2.L0.FullName = md.FullName().Append(pref.Name(strs.MapEntryName(string(fd.Name()))))
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md2.L0.ParentFile = md.L0.ParentFile
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md2.L0.Parent = md
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md2.L0.Index = n
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md2.L2.IsMapEntry = true
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md2.L2.Options = func() pref.ProtoMessage {
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opts := descopts.Message.ProtoReflect().New()
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opts.Set(opts.Descriptor().Fields().ByName("map_entry"), protoreflect.ValueOfBool(true))
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return opts.Interface()
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}
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aberrantAppendField(md2, t.Key(), tagKey, "", "")
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aberrantAppendField(md2, t.Elem(), tagVal, "", "")
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fd.L1.Message = md2
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break
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}
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fd.L1.Message = aberrantLoadMessageDescReentrant(t, "")
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}
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}
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}
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type placeholderEnumValues struct {
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protoreflect.EnumValueDescriptors
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}
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func (placeholderEnumValues) ByNumber(n pref.EnumNumber) pref.EnumValueDescriptor {
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return filedesc.PlaceholderEnumValue(pref.FullName(fmt.Sprintf("UNKNOWN_%d", n)))
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}
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// legacyMarshaler is the proto.Marshaler interface superseded by protoiface.Methoder.
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type legacyMarshaler interface {
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Marshal() ([]byte, error)
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}
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// legacyUnmarshaler is the proto.Unmarshaler interface superseded by protoiface.Methoder.
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type legacyUnmarshaler interface {
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Unmarshal([]byte) error
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}
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var legacyProtoMethods = &piface.Methods{
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Size: legacySize,
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MarshalAppend: legacyMarshalAppend,
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Unmarshal: legacyUnmarshal,
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}
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func legacySize(m protoreflect.Message, opts piface.MarshalOptions) int {
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b, _ := legacyMarshalAppend(nil, m, opts)
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return len(b)
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}
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func legacyMarshalAppend(b []byte, m protoreflect.Message, opts piface.MarshalOptions) ([]byte, error) {
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v := m.(unwrapper).protoUnwrap()
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marshaler, ok := v.(legacyMarshaler)
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if !ok {
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return nil, errors.New("%T does not implement Marshal", v)
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}
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out, err := marshaler.Marshal()
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if b != nil {
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out = append(b, out...)
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}
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return out, err
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}
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func legacyUnmarshal(b []byte, m protoreflect.Message, opts piface.UnmarshalOptions) error {
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v := m.(unwrapper).protoUnwrap()
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unmarshaler, ok := v.(legacyUnmarshaler)
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if !ok {
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return errors.New("%T does not implement Marshal", v)
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}
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return unmarshaler.Unmarshal(b)
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}
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// aberrantMessageType implements MessageType for all types other than pointer-to-struct.
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type aberrantMessageType struct {
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t reflect.Type
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}
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func (mt aberrantMessageType) New() pref.Message {
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return aberrantMessage{reflect.Zero(mt.t)}
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}
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func (mt aberrantMessageType) Zero() pref.Message {
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return aberrantMessage{reflect.Zero(mt.t)}
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}
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func (mt aberrantMessageType) GoType() reflect.Type {
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return mt.t
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}
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func (mt aberrantMessageType) Descriptor() pref.MessageDescriptor {
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return LegacyLoadMessageDesc(mt.t)
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}
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// aberrantMessage implements Message for all types other than pointer-to-struct.
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//
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// When the underlying type implements legacyMarshaler or legacyUnmarshaler,
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// the aberrant Message can be marshaled or unmarshaled. Otherwise, there is
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// not much that can be done with values of this type.
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type aberrantMessage struct {
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v reflect.Value
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}
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func (m aberrantMessage) ProtoReflect() pref.Message {
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return m
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}
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func (m aberrantMessage) Descriptor() pref.MessageDescriptor {
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return LegacyLoadMessageDesc(m.v.Type())
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}
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func (m aberrantMessage) Type() pref.MessageType {
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return aberrantMessageType{m.v.Type()}
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}
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func (m aberrantMessage) New() pref.Message {
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return aberrantMessage{reflect.Zero(m.v.Type())}
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}
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func (m aberrantMessage) Interface() pref.ProtoMessage {
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return m
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}
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func (m aberrantMessage) Range(f func(pref.FieldDescriptor, pref.Value) bool) {
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}
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func (m aberrantMessage) Has(pref.FieldDescriptor) bool {
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panic("invalid field descriptor")
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}
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func (m aberrantMessage) Clear(pref.FieldDescriptor) {
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panic("invalid field descriptor")
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}
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func (m aberrantMessage) Get(pref.FieldDescriptor) pref.Value {
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panic("invalid field descriptor")
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}
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func (m aberrantMessage) Set(pref.FieldDescriptor, pref.Value) {
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panic("invalid field descriptor")
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}
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func (m aberrantMessage) Mutable(pref.FieldDescriptor) pref.Value {
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panic("invalid field descriptor")
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}
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func (m aberrantMessage) NewField(pref.FieldDescriptor) pref.Value {
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panic("invalid field descriptor")
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}
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func (m aberrantMessage) WhichOneof(pref.OneofDescriptor) pref.FieldDescriptor {
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panic("invalid oneof descriptor")
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}
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func (m aberrantMessage) GetUnknown() pref.RawFields {
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return nil
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}
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func (m aberrantMessage) SetUnknown(pref.RawFields) {
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// SetUnknown discards its input on messages which don't support unknown field storage.
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}
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func (m aberrantMessage) ProtoMethods() *piface.Methods {
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return legacyProtoMethods
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}
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func (m aberrantMessage) protoUnwrap() interface{} {
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return m.v.Interface()
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}
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