blob: dbfffe071b82aabab10a91d5b0c084bf7327b89a [file] [log] [blame]
Girish Gowdra64503432020-01-07 10:59:10 +05301// 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, deref bool) (p 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 p = pointer{p: unsafe.Pointer(uintptr(unsafe.Pointer(i)) + ptrSize)}
94 } else {
95 // The interface is not of pointer type. The data word is the pointer
96 // to the data.
97 p = pointer{p: (*[2]unsafe.Pointer)(unsafe.Pointer(i))[1]}
98 }
99 if deref {
100 p.p = *(*unsafe.Pointer)(p.p)
101 }
102 return p
103}
104
105// valToPointer converts v to a pointer. v must be of pointer type.
106func valToPointer(v reflect.Value) pointer {
107 return pointer{p: unsafe.Pointer(v.Pointer())}
108}
109
110// offset converts from a pointer to a structure to a pointer to
111// one of its fields.
112func (p pointer) offset(f field) pointer {
113 // For safety, we should panic if !f.IsValid, however calling panic causes
114 // this to no longer be inlineable, which is a serious performance cost.
115 /*
116 if !f.IsValid() {
117 panic("invalid field")
118 }
119 */
120 return pointer{p: unsafe.Pointer(uintptr(p.p) + uintptr(f))}
121}
122
123func (p pointer) isNil() bool {
124 return p.p == nil
125}
126
127func (p pointer) toInt64() *int64 {
128 return (*int64)(p.p)
129}
130func (p pointer) toInt64Ptr() **int64 {
131 return (**int64)(p.p)
132}
133func (p pointer) toInt64Slice() *[]int64 {
134 return (*[]int64)(p.p)
135}
136func (p pointer) toInt32() *int32 {
137 return (*int32)(p.p)
138}
139
140// See pointer_reflect.go for why toInt32Ptr/Slice doesn't exist.
141/*
142 func (p pointer) toInt32Ptr() **int32 {
143 return (**int32)(p.p)
144 }
145 func (p pointer) toInt32Slice() *[]int32 {
146 return (*[]int32)(p.p)
147 }
148*/
149func (p pointer) getInt32Ptr() *int32 {
150 return *(**int32)(p.p)
151}
152func (p pointer) setInt32Ptr(v int32) {
153 *(**int32)(p.p) = &v
154}
155
156// getInt32Slice loads a []int32 from p.
157// The value returned is aliased with the original slice.
158// This behavior differs from the implementation in pointer_reflect.go.
159func (p pointer) getInt32Slice() []int32 {
160 return *(*[]int32)(p.p)
161}
162
163// setInt32Slice stores a []int32 to p.
164// The value set is aliased with the input slice.
165// This behavior differs from the implementation in pointer_reflect.go.
166func (p pointer) setInt32Slice(v []int32) {
167 *(*[]int32)(p.p) = v
168}
169
170// TODO: Can we get rid of appendInt32Slice and use setInt32Slice instead?
171func (p pointer) appendInt32Slice(v int32) {
172 s := (*[]int32)(p.p)
173 *s = append(*s, v)
174}
175
176func (p pointer) toUint64() *uint64 {
177 return (*uint64)(p.p)
178}
179func (p pointer) toUint64Ptr() **uint64 {
180 return (**uint64)(p.p)
181}
182func (p pointer) toUint64Slice() *[]uint64 {
183 return (*[]uint64)(p.p)
184}
185func (p pointer) toUint32() *uint32 {
186 return (*uint32)(p.p)
187}
188func (p pointer) toUint32Ptr() **uint32 {
189 return (**uint32)(p.p)
190}
191func (p pointer) toUint32Slice() *[]uint32 {
192 return (*[]uint32)(p.p)
193}
194func (p pointer) toBool() *bool {
195 return (*bool)(p.p)
196}
197func (p pointer) toBoolPtr() **bool {
198 return (**bool)(p.p)
199}
200func (p pointer) toBoolSlice() *[]bool {
201 return (*[]bool)(p.p)
202}
203func (p pointer) toFloat64() *float64 {
204 return (*float64)(p.p)
205}
206func (p pointer) toFloat64Ptr() **float64 {
207 return (**float64)(p.p)
208}
209func (p pointer) toFloat64Slice() *[]float64 {
210 return (*[]float64)(p.p)
211}
212func (p pointer) toFloat32() *float32 {
213 return (*float32)(p.p)
214}
215func (p pointer) toFloat32Ptr() **float32 {
216 return (**float32)(p.p)
217}
218func (p pointer) toFloat32Slice() *[]float32 {
219 return (*[]float32)(p.p)
220}
221func (p pointer) toString() *string {
222 return (*string)(p.p)
223}
224func (p pointer) toStringPtr() **string {
225 return (**string)(p.p)
226}
227func (p pointer) toStringSlice() *[]string {
228 return (*[]string)(p.p)
229}
230func (p pointer) toBytes() *[]byte {
231 return (*[]byte)(p.p)
232}
233func (p pointer) toBytesSlice() *[][]byte {
234 return (*[][]byte)(p.p)
235}
236func (p pointer) toExtensions() *XXX_InternalExtensions {
237 return (*XXX_InternalExtensions)(p.p)
238}
239func (p pointer) toOldExtensions() *map[int32]Extension {
240 return (*map[int32]Extension)(p.p)
241}
242
243// getPointerSlice loads []*T from p as a []pointer.
244// The value returned is aliased with the original slice.
245// This behavior differs from the implementation in pointer_reflect.go.
246func (p pointer) getPointerSlice() []pointer {
247 // Super-tricky - p should point to a []*T where T is a
248 // message type. We load it as []pointer.
249 return *(*[]pointer)(p.p)
250}
251
252// setPointerSlice stores []pointer into p as a []*T.
253// The value set is aliased with the input slice.
254// This behavior differs from the implementation in pointer_reflect.go.
255func (p pointer) setPointerSlice(v []pointer) {
256 // Super-tricky - p should point to a []*T where T is a
257 // message type. We store it as []pointer.
258 *(*[]pointer)(p.p) = v
259}
260
261// getPointer loads the pointer at p and returns it.
262func (p pointer) getPointer() pointer {
263 return pointer{p: *(*unsafe.Pointer)(p.p)}
264}
265
266// setPointer stores the pointer q at p.
267func (p pointer) setPointer(q pointer) {
268 *(*unsafe.Pointer)(p.p) = q.p
269}
270
271// append q to the slice pointed to by p.
272func (p pointer) appendPointer(q pointer) {
273 s := (*[]unsafe.Pointer)(p.p)
274 *s = append(*s, q.p)
275}
276
277// getInterfacePointer returns a pointer that points to the
278// interface data of the interface pointed by p.
279func (p pointer) getInterfacePointer() pointer {
280 // Super-tricky - read pointer out of data word of interface value.
281 return pointer{p: (*(*[2]unsafe.Pointer)(p.p))[1]}
282}
283
284// asPointerTo returns a reflect.Value that is a pointer to an
285// object of type t stored at p.
286func (p pointer) asPointerTo(t reflect.Type) reflect.Value {
287 return reflect.NewAt(t, p.p)
288}
289
290func atomicLoadUnmarshalInfo(p **unmarshalInfo) *unmarshalInfo {
291 return (*unmarshalInfo)(atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(p))))
292}
293func atomicStoreUnmarshalInfo(p **unmarshalInfo, v *unmarshalInfo) {
294 atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(p)), unsafe.Pointer(v))
295}
296func atomicLoadMarshalInfo(p **marshalInfo) *marshalInfo {
297 return (*marshalInfo)(atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(p))))
298}
299func atomicStoreMarshalInfo(p **marshalInfo, v *marshalInfo) {
300 atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(p)), unsafe.Pointer(v))
301}
302func atomicLoadMergeInfo(p **mergeInfo) *mergeInfo {
303 return (*mergeInfo)(atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(p))))
304}
305func atomicStoreMergeInfo(p **mergeInfo, v *mergeInfo) {
306 atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(p)), unsafe.Pointer(v))
307}
308func atomicLoadDiscardInfo(p **discardInfo) *discardInfo {
309 return (*discardInfo)(atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(p))))
310}
311func atomicStoreDiscardInfo(p **discardInfo, v *discardInfo) {
312 atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(p)), unsafe.Pointer(v))
313}