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	"fmt"
9	"reflect"
10	"strings"
11	"sync"
12
13	"google.golang.org/protobuf/internal/filedesc"
14	"google.golang.org/protobuf/internal/strs"
15	"google.golang.org/protobuf/reflect/protoreflect"
16	pref "google.golang.org/protobuf/reflect/protoreflect"
17)
18
19// legacyEnumName returns the name of enums used in legacy code.
20// It is neither the protobuf full name nor the qualified Go name,
21// but rather an odd hybrid of both.
22func legacyEnumName(ed pref.EnumDescriptor) string {
23	var protoPkg string
24	enumName := string(ed.FullName())
25	if fd := ed.ParentFile(); fd != nil {
26		protoPkg = string(fd.Package())
27		enumName = strings.TrimPrefix(enumName, protoPkg+".")
28	}
29	if protoPkg == "" {
30		return strs.GoCamelCase(enumName)
31	}
32	return protoPkg + "." + strs.GoCamelCase(enumName)
33}
34
35// legacyWrapEnum wraps v as a protoreflect.Enum,
36// where v must be a int32 kind and not implement the v2 API already.
37func legacyWrapEnum(v reflect.Value) pref.Enum {
38	et := legacyLoadEnumType(v.Type())
39	return et.New(pref.EnumNumber(v.Int()))
40}
41
42var legacyEnumTypeCache sync.Map // map[reflect.Type]protoreflect.EnumType
43
44// legacyLoadEnumType dynamically loads a protoreflect.EnumType for t,
45// where t must be an int32 kind and not implement the v2 API already.
46func legacyLoadEnumType(t reflect.Type) pref.EnumType {
47	// Fast-path: check if a EnumType is cached for this concrete type.
48	if et, ok := legacyEnumTypeCache.Load(t); ok {
49		return et.(pref.EnumType)
50	}
51
52	// Slow-path: derive enum descriptor and initialize EnumType.
53	var et pref.EnumType
54	ed := LegacyLoadEnumDesc(t)
55	et = &legacyEnumType{
56		desc:   ed,
57		goType: t,
58	}
59	if et, ok := legacyEnumTypeCache.LoadOrStore(t, et); ok {
60		return et.(pref.EnumType)
61	}
62	return et
63}
64
65type legacyEnumType struct {
66	desc   pref.EnumDescriptor
67	goType reflect.Type
68	m      sync.Map // map[protoreflect.EnumNumber]proto.Enum
69}
70
71func (t *legacyEnumType) New(n pref.EnumNumber) pref.Enum {
72	if e, ok := t.m.Load(n); ok {
73		return e.(pref.Enum)
74	}
75	e := &legacyEnumWrapper{num: n, pbTyp: t, goTyp: t.goType}
76	t.m.Store(n, e)
77	return e
78}
79func (t *legacyEnumType) Descriptor() pref.EnumDescriptor {
80	return t.desc
81}
82
83type legacyEnumWrapper struct {
84	num   pref.EnumNumber
85	pbTyp pref.EnumType
86	goTyp reflect.Type
87}
88
89func (e *legacyEnumWrapper) Descriptor() pref.EnumDescriptor {
90	return e.pbTyp.Descriptor()
91}
92func (e *legacyEnumWrapper) Type() pref.EnumType {
93	return e.pbTyp
94}
95func (e *legacyEnumWrapper) Number() pref.EnumNumber {
96	return e.num
97}
98func (e *legacyEnumWrapper) ProtoReflect() pref.Enum {
99	return e
100}
101func (e *legacyEnumWrapper) protoUnwrap() interface{} {
102	v := reflect.New(e.goTyp).Elem()
103	v.SetInt(int64(e.num))
104	return v.Interface()
105}
106
107var (
108	_ pref.Enum = (*legacyEnumWrapper)(nil)
109	_ unwrapper = (*legacyEnumWrapper)(nil)
110)
111
112var legacyEnumDescCache sync.Map // map[reflect.Type]protoreflect.EnumDescriptor
113
114// LegacyLoadEnumDesc returns an EnumDescriptor derived from the Go type,
115// which must be an int32 kind and not implement the v2 API already.
116//
117// This is exported for testing purposes.
118func LegacyLoadEnumDesc(t reflect.Type) pref.EnumDescriptor {
119	// Fast-path: check if an EnumDescriptor is cached for this concrete type.
120	if ed, ok := legacyEnumDescCache.Load(t); ok {
121		return ed.(pref.EnumDescriptor)
122	}
123
124	// Slow-path: initialize EnumDescriptor from the raw descriptor.
125	ev := reflect.Zero(t).Interface()
126	if _, ok := ev.(pref.Enum); ok {
127		panic(fmt.Sprintf("%v already implements proto.Enum", t))
128	}
129	edV1, ok := ev.(enumV1)
130	if !ok {
131		return aberrantLoadEnumDesc(t)
132	}
133	b, idxs := edV1.EnumDescriptor()
134
135	var ed pref.EnumDescriptor
136	if len(idxs) == 1 {
137		ed = legacyLoadFileDesc(b).Enums().Get(idxs[0])
138	} else {
139		md := legacyLoadFileDesc(b).Messages().Get(idxs[0])
140		for _, i := range idxs[1 : len(idxs)-1] {
141			md = md.Messages().Get(i)
142		}
143		ed = md.Enums().Get(idxs[len(idxs)-1])
144	}
145	if ed, ok := legacyEnumDescCache.LoadOrStore(t, ed); ok {
146		return ed.(protoreflect.EnumDescriptor)
147	}
148	return ed
149}
150
151var aberrantEnumDescCache sync.Map // map[reflect.Type]protoreflect.EnumDescriptor
152
153// aberrantLoadEnumDesc returns an EnumDescriptor derived from the Go type,
154// which must not implement protoreflect.Enum or enumV1.
155//
156// If the type does not implement enumV1, then there is no reliable
157// way to derive the original protobuf type information.
158// We are unable to use the global enum registry since it is
159// unfortunately keyed by the protobuf full name, which we also do not know.
160// Thus, this produces some bogus enum descriptor based on the Go type name.
161func aberrantLoadEnumDesc(t reflect.Type) pref.EnumDescriptor {
162	// Fast-path: check if an EnumDescriptor is cached for this concrete type.
163	if ed, ok := aberrantEnumDescCache.Load(t); ok {
164		return ed.(pref.EnumDescriptor)
165	}
166
167	// Slow-path: construct a bogus, but unique EnumDescriptor.
168	ed := &filedesc.Enum{L2: new(filedesc.EnumL2)}
169	ed.L0.FullName = AberrantDeriveFullName(t) // e.g., github_com.user.repo.MyEnum
170	ed.L0.ParentFile = filedesc.SurrogateProto3
171	ed.L2.Values.List = append(ed.L2.Values.List, filedesc.EnumValue{})
172
173	// TODO: Use the presence of a UnmarshalJSON method to determine proto2?
174
175	vd := &ed.L2.Values.List[0]
176	vd.L0.FullName = ed.L0.FullName + "_UNKNOWN" // e.g., github_com.user.repo.MyEnum_UNKNOWN
177	vd.L0.ParentFile = ed.L0.ParentFile
178	vd.L0.Parent = ed
179
180	// TODO: We could use the String method to obtain some enum value names by
181	// starting at 0 and print the enum until it produces invalid identifiers.
182	// An exhaustive query is clearly impractical, but can be best-effort.
183
184	if ed, ok := aberrantEnumDescCache.LoadOrStore(t, ed); ok {
185		return ed.(pref.EnumDescriptor)
186	}
187	return ed
188}
189
190// AberrantDeriveFullName derives a fully qualified protobuf name for the given Go type
191// The provided name is not guaranteed to be stable nor universally unique.
192// It should be sufficiently unique within a program.
193//
194// This is exported for testing purposes.
195func AberrantDeriveFullName(t reflect.Type) pref.FullName {
196	sanitize := func(r rune) rune {
197		switch {
198		case r == '/':
199			return '.'
200		case 'a' <= r && r <= 'z', 'A' <= r && r <= 'Z', '0' <= r && r <= '9':
201			return r
202		default:
203			return '_'
204		}
205	}
206	prefix := strings.Map(sanitize, t.PkgPath())
207	suffix := strings.Map(sanitize, t.Name())
208	if suffix == "" {
209		suffix = fmt.Sprintf("UnknownX%X", reflect.ValueOf(t).Pointer())
210	}
211
212	ss := append(strings.Split(prefix, "."), suffix)
213	for i, s := range ss {
214		if s == "" || ('0' <= s[0] && s[0] <= '9') {
215			ss[i] = "x" + s
216		}
217	}
218	return pref.FullName(strings.Join(ss, "."))
219}
220