1// 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	"reflect"
9
10	"google.golang.org/protobuf/internal/descopts"
11	"google.golang.org/protobuf/internal/encoding/messageset"
12	ptag "google.golang.org/protobuf/internal/encoding/tag"
13	"google.golang.org/protobuf/internal/filedesc"
14	"google.golang.org/protobuf/internal/pragma"
15	pref "google.golang.org/protobuf/reflect/protoreflect"
16	preg "google.golang.org/protobuf/reflect/protoregistry"
17	piface "google.golang.org/protobuf/runtime/protoiface"
18)
19
20func (xi *ExtensionInfo) initToLegacy() {
21	xd := xi.desc
22	var parent piface.MessageV1
23	messageName := xd.ContainingMessage().FullName()
24	if mt, _ := preg.GlobalTypes.FindMessageByName(messageName); mt != nil {
25		// Create a new parent message and unwrap it if possible.
26		mv := mt.New().Interface()
27		t := reflect.TypeOf(mv)
28		if mv, ok := mv.(unwrapper); ok {
29			t = reflect.TypeOf(mv.protoUnwrap())
30		}
31
32		// Check whether the message implements the legacy v1 Message interface.
33		mz := reflect.Zero(t).Interface()
34		if mz, ok := mz.(piface.MessageV1); ok {
35			parent = mz
36		}
37	}
38
39	// Determine the v1 extension type, which is unfortunately not the same as
40	// the v2 ExtensionType.GoType.
41	extType := xi.goType
42	switch extType.Kind() {
43	case reflect.Bool, reflect.Int32, reflect.Int64, reflect.Uint32, reflect.Uint64, reflect.Float32, reflect.Float64, reflect.String:
44		extType = reflect.PtrTo(extType) // T -> *T for singular scalar fields
45	}
46
47	// Reconstruct the legacy enum full name.
48	var enumName string
49	if xd.Kind() == pref.EnumKind {
50		enumName = legacyEnumName(xd.Enum())
51	}
52
53	// Derive the proto file that the extension was declared within.
54	var filename string
55	if fd := xd.ParentFile(); fd != nil {
56		filename = fd.Path()
57	}
58
59	// For MessageSet extensions, the name used is the parent message.
60	name := xd.FullName()
61	if messageset.IsMessageSetExtension(xd) {
62		name = name.Parent()
63	}
64
65	xi.ExtendedType = parent
66	xi.ExtensionType = reflect.Zero(extType).Interface()
67	xi.Field = int32(xd.Number())
68	xi.Name = string(name)
69	xi.Tag = ptag.Marshal(xd, enumName)
70	xi.Filename = filename
71}
72
73// initFromLegacy initializes an ExtensionInfo from
74// the contents of the deprecated exported fields of the type.
75func (xi *ExtensionInfo) initFromLegacy() {
76	// The v1 API returns "type incomplete" descriptors where only the
77	// field number is specified. In such a case, use a placeholder.
78	if xi.ExtendedType == nil || xi.ExtensionType == nil {
79		xd := placeholderExtension{
80			name:   pref.FullName(xi.Name),
81			number: pref.FieldNumber(xi.Field),
82		}
83		xi.desc = extensionTypeDescriptor{xd, xi}
84		return
85	}
86
87	// Resolve enum or message dependencies.
88	var ed pref.EnumDescriptor
89	var md pref.MessageDescriptor
90	t := reflect.TypeOf(xi.ExtensionType)
91	isOptional := t.Kind() == reflect.Ptr && t.Elem().Kind() != reflect.Struct
92	isRepeated := t.Kind() == reflect.Slice && t.Elem().Kind() != reflect.Uint8
93	if isOptional || isRepeated {
94		t = t.Elem()
95	}
96	switch v := reflect.Zero(t).Interface().(type) {
97	case pref.Enum:
98		ed = v.Descriptor()
99	case enumV1:
100		ed = LegacyLoadEnumDesc(t)
101	case pref.ProtoMessage:
102		md = v.ProtoReflect().Descriptor()
103	case messageV1:
104		md = LegacyLoadMessageDesc(t)
105	}
106
107	// Derive basic field information from the struct tag.
108	var evs pref.EnumValueDescriptors
109	if ed != nil {
110		evs = ed.Values()
111	}
112	fd := ptag.Unmarshal(xi.Tag, t, evs).(*filedesc.Field)
113
114	// Construct a v2 ExtensionType.
115	xd := &filedesc.Extension{L2: new(filedesc.ExtensionL2)}
116	xd.L0.ParentFile = filedesc.SurrogateProto2
117	xd.L0.FullName = pref.FullName(xi.Name)
118	xd.L1.Number = pref.FieldNumber(xi.Field)
119	xd.L1.Cardinality = fd.L1.Cardinality
120	xd.L1.Kind = fd.L1.Kind
121	xd.L2.IsPacked = fd.L1.IsPacked
122	xd.L2.Default = fd.L1.Default
123	xd.L1.Extendee = Export{}.MessageDescriptorOf(xi.ExtendedType)
124	xd.L2.Enum = ed
125	xd.L2.Message = md
126
127	// Derive real extension field name for MessageSets.
128	if messageset.IsMessageSet(xd.L1.Extendee) && md.FullName() == xd.L0.FullName {
129		xd.L0.FullName = xd.L0.FullName.Append(messageset.ExtensionName)
130	}
131
132	tt := reflect.TypeOf(xi.ExtensionType)
133	if isOptional {
134		tt = tt.Elem()
135	}
136	xi.goType = tt
137	xi.desc = extensionTypeDescriptor{xd, xi}
138}
139
140type placeholderExtension struct {
141	name   pref.FullName
142	number pref.FieldNumber
143}
144
145func (x placeholderExtension) ParentFile() pref.FileDescriptor            { return nil }
146func (x placeholderExtension) Parent() pref.Descriptor                    { return nil }
147func (x placeholderExtension) Index() int                                 { return 0 }
148func (x placeholderExtension) Syntax() pref.Syntax                        { return 0 }
149func (x placeholderExtension) Name() pref.Name                            { return x.name.Name() }
150func (x placeholderExtension) FullName() pref.FullName                    { return x.name }
151func (x placeholderExtension) IsPlaceholder() bool                        { return true }
152func (x placeholderExtension) Options() pref.ProtoMessage                 { return descopts.Field }
153func (x placeholderExtension) Number() pref.FieldNumber                   { return x.number }
154func (x placeholderExtension) Cardinality() pref.Cardinality              { return 0 }
155func (x placeholderExtension) Kind() pref.Kind                            { return 0 }
156func (x placeholderExtension) HasJSONName() bool                          { return false }
157func (x placeholderExtension) JSONName() string                           { return "" }
158func (x placeholderExtension) HasPresence() bool                          { return false }
159func (x placeholderExtension) HasOptionalKeyword() bool                   { return false }
160func (x placeholderExtension) IsExtension() bool                          { return true }
161func (x placeholderExtension) IsWeak() bool                               { return false }
162func (x placeholderExtension) IsPacked() bool                             { return false }
163func (x placeholderExtension) IsList() bool                               { return false }
164func (x placeholderExtension) IsMap() bool                                { return false }
165func (x placeholderExtension) MapKey() pref.FieldDescriptor               { return nil }
166func (x placeholderExtension) MapValue() pref.FieldDescriptor             { return nil }
167func (x placeholderExtension) HasDefault() bool                           { return false }
168func (x placeholderExtension) Default() pref.Value                        { return pref.Value{} }
169func (x placeholderExtension) DefaultEnumValue() pref.EnumValueDescriptor { return nil }
170func (x placeholderExtension) ContainingOneof() pref.OneofDescriptor      { return nil }
171func (x placeholderExtension) ContainingMessage() pref.MessageDescriptor  { return nil }
172func (x placeholderExtension) Enum() pref.EnumDescriptor                  { return nil }
173func (x placeholderExtension) Message() pref.MessageDescriptor            { return nil }
174func (x placeholderExtension) ProtoType(pref.FieldDescriptor)             { return }
175func (x placeholderExtension) ProtoInternal(pragma.DoNotImplement)        { return }
176