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 "sync/atomic"
10 "unsafe"
11
12 "google.golang.org/protobuf/internal/protolazy"
13)
14
15const UnsafeEnabled = true
16
17// Pointer is an opaque pointer type.
18type Pointer unsafe.Pointer
19
20// offset represents the offset to a struct field, accessible from a pointer.
21// The offset is the byte offset to the field from the start of the struct.
22type offset uintptr
23
24// offsetOf returns a field offset for the struct field.
25func offsetOf(f reflect.StructField) offset {
26 return offset(f.Offset)
27}
28
29// IsValid reports whether the offset is valid.
30func (f offset) IsValid() bool { return f != invalidOffset }
31
32// invalidOffset is an invalid field offset.
33var invalidOffset = ^offset(0)
34
35// zeroOffset is a noop when calling pointer.Apply.
36var zeroOffset = offset(0)
37
38// pointer is a pointer to a message struct or field.
39type pointer struct{ p unsafe.Pointer }
40
41// pointerOf returns p as a pointer.
42func pointerOf(p Pointer) pointer {
43 return pointer{p: unsafe.Pointer(p)}
44}
45
46// pointerOfValue returns v as a pointer.
47func pointerOfValue(v reflect.Value) pointer {
48 return pointer{p: unsafe.Pointer(v.Pointer())}
49}
50
51// pointerOfIface returns the pointer portion of an interface.
52func pointerOfIface(v any) pointer {
53 type ifaceHeader struct {
54 Type unsafe.Pointer
55 Data unsafe.Pointer
56 }
57 return pointer{p: (*ifaceHeader)(unsafe.Pointer(&v)).Data}
58}
59
60// IsNil reports whether the pointer is nil.
61func (p pointer) IsNil() bool {
62 return p.p == nil
63}
64
65// Apply adds an offset to the pointer to derive a new pointer
66// to a specified field. The pointer must be valid and pointing at a struct.
67func (p pointer) Apply(f offset) pointer {
68 if p.IsNil() {
69 panic("invalid nil pointer")
70 }
71 return pointer{p: unsafe.Pointer(uintptr(p.p) + uintptr(f))}
72}
73
74// AsValueOf treats p as a pointer to an object of type t and returns the value.
75// It is equivalent to reflect.ValueOf(p.AsIfaceOf(t))
76func (p pointer) AsValueOf(t reflect.Type) reflect.Value {
77 return reflect.NewAt(t, p.p)
78}
79
80// AsIfaceOf treats p as a pointer to an object of type t and returns the value.
81// It is equivalent to p.AsValueOf(t).Interface()
82func (p pointer) AsIfaceOf(t reflect.Type) any {
83 // TODO: Use tricky unsafe magic to directly create ifaceHeader.
84 return p.AsValueOf(t).Interface()
85}
86
87func (p pointer) Bool() *bool { return (*bool)(p.p) }
88func (p pointer) BoolPtr() **bool { return (**bool)(p.p) }
89func (p pointer) BoolSlice() *[]bool { return (*[]bool)(p.p) }
90func (p pointer) Int32() *int32 { return (*int32)(p.p) }
91func (p pointer) Int32Ptr() **int32 { return (**int32)(p.p) }
92func (p pointer) Int32Slice() *[]int32 { return (*[]int32)(p.p) }
93func (p pointer) Int64() *int64 { return (*int64)(p.p) }
94func (p pointer) Int64Ptr() **int64 { return (**int64)(p.p) }
95func (p pointer) Int64Slice() *[]int64 { return (*[]int64)(p.p) }
96func (p pointer) Uint32() *uint32 { return (*uint32)(p.p) }
97func (p pointer) Uint32Ptr() **uint32 { return (**uint32)(p.p) }
98func (p pointer) Uint32Slice() *[]uint32 { return (*[]uint32)(p.p) }
99func (p pointer) Uint64() *uint64 { return (*uint64)(p.p) }
100func (p pointer) Uint64Ptr() **uint64 { return (**uint64)(p.p) }
101func (p pointer) Uint64Slice() *[]uint64 { return (*[]uint64)(p.p) }
102func (p pointer) Float32() *float32 { return (*float32)(p.p) }
103func (p pointer) Float32Ptr() **float32 { return (**float32)(p.p) }
104func (p pointer) Float32Slice() *[]float32 { return (*[]float32)(p.p) }
105func (p pointer) Float64() *float64 { return (*float64)(p.p) }
106func (p pointer) Float64Ptr() **float64 { return (**float64)(p.p) }
107func (p pointer) Float64Slice() *[]float64 { return (*[]float64)(p.p) }
108func (p pointer) String() *string { return (*string)(p.p) }
109func (p pointer) StringPtr() **string { return (**string)(p.p) }
110func (p pointer) StringSlice() *[]string { return (*[]string)(p.p) }
111func (p pointer) Bytes() *[]byte { return (*[]byte)(p.p) }
112func (p pointer) BytesPtr() **[]byte { return (**[]byte)(p.p) }
113func (p pointer) BytesSlice() *[][]byte { return (*[][]byte)(p.p) }
114func (p pointer) Extensions() *map[int32]ExtensionField { return (*map[int32]ExtensionField)(p.p) }
115func (p pointer) LazyInfoPtr() **protolazy.XXX_lazyUnmarshalInfo {
116 return (**protolazy.XXX_lazyUnmarshalInfo)(p.p)
117}
118
119func (p pointer) PresenceInfo() presence {
120 return presence{P: p.p}
121}
122
123func (p pointer) Elem() pointer {
124 return pointer{p: *(*unsafe.Pointer)(p.p)}
125}
126
127// PointerSlice loads []*T from p as a []pointer.
128// The value returned is aliased with the original slice.
129// This behavior differs from the implementation in pointer_reflect.go.
130func (p pointer) PointerSlice() []pointer {
131 // Super-tricky - p should point to a []*T where T is a
132 // message type. We load it as []pointer.
133 return *(*[]pointer)(p.p)
134}
135
136// AppendPointerSlice appends v to p, which must be a []*T.
137func (p pointer) AppendPointerSlice(v pointer) {
138 *(*[]pointer)(p.p) = append(*(*[]pointer)(p.p), v)
139}
140
141// SetPointer sets *p to v.
142func (p pointer) SetPointer(v pointer) {
143 *(*unsafe.Pointer)(p.p) = (unsafe.Pointer)(v.p)
144}
145
146func (p pointer) growBoolSlice(addCap int) {
147 sp := p.BoolSlice()
148 s := make([]bool, 0, addCap+len(*sp))
149 s = s[:len(*sp)]
150 copy(s, *sp)
151 *sp = s
152}
153
154func (p pointer) growInt32Slice(addCap int) {
155 sp := p.Int32Slice()
156 s := make([]int32, 0, addCap+len(*sp))
157 s = s[:len(*sp)]
158 copy(s, *sp)
159 *sp = s
160}
161
162func (p pointer) growUint32Slice(addCap int) {
163 p.growInt32Slice(addCap)
164}
165
166func (p pointer) growFloat32Slice(addCap int) {
167 p.growInt32Slice(addCap)
168}
169
170func (p pointer) growInt64Slice(addCap int) {
171 sp := p.Int64Slice()
172 s := make([]int64, 0, addCap+len(*sp))
173 s = s[:len(*sp)]
174 copy(s, *sp)
175 *sp = s
176}
177
178func (p pointer) growUint64Slice(addCap int) {
179 p.growInt64Slice(addCap)
180}
181
182func (p pointer) growFloat64Slice(addCap int) {
183 p.growInt64Slice(addCap)
184}
185
186// Static check that MessageState does not exceed the size of a pointer.
187const _ = uint(unsafe.Sizeof(unsafe.Pointer(nil)) - unsafe.Sizeof(MessageState{}))
188
189func (Export) MessageStateOf(p Pointer) *messageState {
190 // Super-tricky - see documentation on MessageState.
191 return (*messageState)(unsafe.Pointer(p))
192}
193func (ms *messageState) pointer() pointer {
194 // Super-tricky - see documentation on MessageState.
195 return pointer{p: unsafe.Pointer(ms)}
196}
197func (ms *messageState) messageInfo() *MessageInfo {
198 mi := ms.LoadMessageInfo()
199 if mi == nil {
200 panic("invalid nil message info; this suggests memory corruption due to a race or shallow copy on the message struct")
201 }
202 return mi
203}
204func (ms *messageState) LoadMessageInfo() *MessageInfo {
205 return (*MessageInfo)(atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(&ms.atomicMessageInfo))))
206}
207func (ms *messageState) StoreMessageInfo(mi *MessageInfo) {
208 atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(&ms.atomicMessageInfo)), unsafe.Pointer(mi))
209}
210
211type atomicNilMessage struct{ p unsafe.Pointer } // p is a *messageReflectWrapper
212
213func (m *atomicNilMessage) Init(mi *MessageInfo) *messageReflectWrapper {
214 if p := atomic.LoadPointer(&m.p); p != nil {
215 return (*messageReflectWrapper)(p)
216 }
217 w := &messageReflectWrapper{mi: mi}
218 atomic.CompareAndSwapPointer(&m.p, nil, (unsafe.Pointer)(w))
219 return (*messageReflectWrapper)(atomic.LoadPointer(&m.p))
220}