blob: d55a335d9453204ae01c7c21d474efdbefa7d120 [file] [log] [blame]
Scott Baker2d897982019-09-24 11:50:08 -07001// Go support for Protocol Buffers - Google's data interchange format
2//
3// Copyright 2012 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// +build !purego,!appengine,!js
33
34// This file contains the implementation of the proto field accesses using package unsafe.
35
36package proto
37
38import (
39 "reflect"
40 "sync/atomic"
41 "unsafe"
42)
43
44const unsafeAllowed = true
45
46// A field identifies a field in a struct, accessible from a pointer.
47// In this implementation, a field is identified by its byte offset from the start of the struct.
48type field uintptr
49
50// toField returns a field equivalent to the given reflect field.
51func toField(f *reflect.StructField) field {
52 return field(f.Offset)
53}
54
55// invalidField is an invalid field identifier.
56const invalidField = ^field(0)
57
58// zeroField is a noop when calling pointer.offset.
59const zeroField = field(0)
60
61// IsValid reports whether the field identifier is valid.
62func (f field) IsValid() bool {
63 return f != invalidField
64}
65
66// The pointer type below is for the new table-driven encoder/decoder.
67// The implementation here uses unsafe.Pointer to create a generic pointer.
68// In pointer_reflect.go we use reflect instead of unsafe to implement
69// the same (but slower) interface.
70type pointer struct {
71 p unsafe.Pointer
72}
73
74// size of pointer
75var ptrSize = unsafe.Sizeof(uintptr(0))
76
77// toPointer converts an interface of pointer type to a pointer
78// that points to the same target.
79func toPointer(i *Message) pointer {
80 // Super-tricky - read pointer out of data word of interface value.
81 // Saves ~25ns over the equivalent:
82 // return valToPointer(reflect.ValueOf(*i))
83 return pointer{p: (*[2]unsafe.Pointer)(unsafe.Pointer(i))[1]}
84}
85
86// toAddrPointer converts an interface to a pointer that points to
87// the interface data.
88func toAddrPointer(i *interface{}, isptr bool) pointer {
89 // Super-tricky - read or get the address of data word of interface value.
90 if isptr {
91 // The interface is of pointer type, thus it is a direct interface.
92 // The data word is the pointer data itself. We take its address.
93 return pointer{p: unsafe.Pointer(uintptr(unsafe.Pointer(i)) + ptrSize)}
94 }
95 // The interface is not of pointer type. The data word is the pointer
96 // to the data.
97 return pointer{p: (*[2]unsafe.Pointer)(unsafe.Pointer(i))[1]}
98}
99
100// valToPointer converts v to a pointer. v must be of pointer type.
101func valToPointer(v reflect.Value) pointer {
102 return pointer{p: unsafe.Pointer(v.Pointer())}
103}
104
105// offset converts from a pointer to a structure to a pointer to
106// one of its fields.
107func (p pointer) offset(f field) pointer {
108 // For safety, we should panic if !f.IsValid, however calling panic causes
109 // this to no longer be inlineable, which is a serious performance cost.
110 /*
111 if !f.IsValid() {
112 panic("invalid field")
113 }
114 */
115 return pointer{p: unsafe.Pointer(uintptr(p.p) + uintptr(f))}
116}
117
118func (p pointer) isNil() bool {
119 return p.p == nil
120}
121
122func (p pointer) toInt64() *int64 {
123 return (*int64)(p.p)
124}
125func (p pointer) toInt64Ptr() **int64 {
126 return (**int64)(p.p)
127}
128func (p pointer) toInt64Slice() *[]int64 {
129 return (*[]int64)(p.p)
130}
131func (p pointer) toInt32() *int32 {
132 return (*int32)(p.p)
133}
134
135// See pointer_reflect.go for why toInt32Ptr/Slice doesn't exist.
136/*
137 func (p pointer) toInt32Ptr() **int32 {
138 return (**int32)(p.p)
139 }
140 func (p pointer) toInt32Slice() *[]int32 {
141 return (*[]int32)(p.p)
142 }
143*/
144func (p pointer) getInt32Ptr() *int32 {
145 return *(**int32)(p.p)
146}
147func (p pointer) setInt32Ptr(v int32) {
148 *(**int32)(p.p) = &v
149}
150
151// getInt32Slice loads a []int32 from p.
152// The value returned is aliased with the original slice.
153// This behavior differs from the implementation in pointer_reflect.go.
154func (p pointer) getInt32Slice() []int32 {
155 return *(*[]int32)(p.p)
156}
157
158// setInt32Slice stores a []int32 to p.
159// The value set is aliased with the input slice.
160// This behavior differs from the implementation in pointer_reflect.go.
161func (p pointer) setInt32Slice(v []int32) {
162 *(*[]int32)(p.p) = v
163}
164
165// TODO: Can we get rid of appendInt32Slice and use setInt32Slice instead?
166func (p pointer) appendInt32Slice(v int32) {
167 s := (*[]int32)(p.p)
168 *s = append(*s, v)
169}
170
171func (p pointer) toUint64() *uint64 {
172 return (*uint64)(p.p)
173}
174func (p pointer) toUint64Ptr() **uint64 {
175 return (**uint64)(p.p)
176}
177func (p pointer) toUint64Slice() *[]uint64 {
178 return (*[]uint64)(p.p)
179}
180func (p pointer) toUint32() *uint32 {
181 return (*uint32)(p.p)
182}
183func (p pointer) toUint32Ptr() **uint32 {
184 return (**uint32)(p.p)
185}
186func (p pointer) toUint32Slice() *[]uint32 {
187 return (*[]uint32)(p.p)
188}
189func (p pointer) toBool() *bool {
190 return (*bool)(p.p)
191}
192func (p pointer) toBoolPtr() **bool {
193 return (**bool)(p.p)
194}
195func (p pointer) toBoolSlice() *[]bool {
196 return (*[]bool)(p.p)
197}
198func (p pointer) toFloat64() *float64 {
199 return (*float64)(p.p)
200}
201func (p pointer) toFloat64Ptr() **float64 {
202 return (**float64)(p.p)
203}
204func (p pointer) toFloat64Slice() *[]float64 {
205 return (*[]float64)(p.p)
206}
207func (p pointer) toFloat32() *float32 {
208 return (*float32)(p.p)
209}
210func (p pointer) toFloat32Ptr() **float32 {
211 return (**float32)(p.p)
212}
213func (p pointer) toFloat32Slice() *[]float32 {
214 return (*[]float32)(p.p)
215}
216func (p pointer) toString() *string {
217 return (*string)(p.p)
218}
219func (p pointer) toStringPtr() **string {
220 return (**string)(p.p)
221}
222func (p pointer) toStringSlice() *[]string {
223 return (*[]string)(p.p)
224}
225func (p pointer) toBytes() *[]byte {
226 return (*[]byte)(p.p)
227}
228func (p pointer) toBytesSlice() *[][]byte {
229 return (*[][]byte)(p.p)
230}
231func (p pointer) toExtensions() *XXX_InternalExtensions {
232 return (*XXX_InternalExtensions)(p.p)
233}
234func (p pointer) toOldExtensions() *map[int32]Extension {
235 return (*map[int32]Extension)(p.p)
236}
237
238// getPointerSlice loads []*T from p as a []pointer.
239// The value returned is aliased with the original slice.
240// This behavior differs from the implementation in pointer_reflect.go.
241func (p pointer) getPointerSlice() []pointer {
242 // Super-tricky - p should point to a []*T where T is a
243 // message type. We load it as []pointer.
244 return *(*[]pointer)(p.p)
245}
246
247// setPointerSlice stores []pointer into p as a []*T.
248// The value set is aliased with the input slice.
249// This behavior differs from the implementation in pointer_reflect.go.
250func (p pointer) setPointerSlice(v []pointer) {
251 // Super-tricky - p should point to a []*T where T is a
252 // message type. We store it as []pointer.
253 *(*[]pointer)(p.p) = v
254}
255
256// getPointer loads the pointer at p and returns it.
257func (p pointer) getPointer() pointer {
258 return pointer{p: *(*unsafe.Pointer)(p.p)}
259}
260
261// setPointer stores the pointer q at p.
262func (p pointer) setPointer(q pointer) {
263 *(*unsafe.Pointer)(p.p) = q.p
264}
265
266// append q to the slice pointed to by p.
267func (p pointer) appendPointer(q pointer) {
268 s := (*[]unsafe.Pointer)(p.p)
269 *s = append(*s, q.p)
270}
271
272// getInterfacePointer returns a pointer that points to the
273// interface data of the interface pointed by p.
274func (p pointer) getInterfacePointer() pointer {
275 // Super-tricky - read pointer out of data word of interface value.
276 return pointer{p: (*(*[2]unsafe.Pointer)(p.p))[1]}
277}
278
279// asPointerTo returns a reflect.Value that is a pointer to an
280// object of type t stored at p.
281func (p pointer) asPointerTo(t reflect.Type) reflect.Value {
282 return reflect.NewAt(t, p.p)
283}
284
285func atomicLoadUnmarshalInfo(p **unmarshalInfo) *unmarshalInfo {
286 return (*unmarshalInfo)(atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(p))))
287}
288func atomicStoreUnmarshalInfo(p **unmarshalInfo, v *unmarshalInfo) {
289 atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(p)), unsafe.Pointer(v))
290}
291func atomicLoadMarshalInfo(p **marshalInfo) *marshalInfo {
292 return (*marshalInfo)(atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(p))))
293}
294func atomicStoreMarshalInfo(p **marshalInfo, v *marshalInfo) {
295 atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(p)), unsafe.Pointer(v))
296}
297func atomicLoadMergeInfo(p **mergeInfo) *mergeInfo {
298 return (*mergeInfo)(atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(p))))
299}
300func atomicStoreMergeInfo(p **mergeInfo, v *mergeInfo) {
301 atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(p)), unsafe.Pointer(v))
302}
303func atomicLoadDiscardInfo(p **discardInfo) *discardInfo {
304 return (*discardInfo)(atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(p))))
305}
306func atomicStoreDiscardInfo(p **discardInfo, v *discardInfo) {
307 atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(p)), unsafe.Pointer(v))
308}