Scott Baker | 2d89798 | 2019-09-24 11:50:08 -0700 | [diff] [blame^] | 1 | // 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 | |
| 36 | package proto |
| 37 | |
| 38 | import ( |
| 39 | "reflect" |
| 40 | "sync/atomic" |
| 41 | "unsafe" |
| 42 | ) |
| 43 | |
| 44 | const 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. |
| 48 | type field uintptr |
| 49 | |
| 50 | // toField returns a field equivalent to the given reflect field. |
| 51 | func toField(f *reflect.StructField) field { |
| 52 | return field(f.Offset) |
| 53 | } |
| 54 | |
| 55 | // invalidField is an invalid field identifier. |
| 56 | const invalidField = ^field(0) |
| 57 | |
| 58 | // zeroField is a noop when calling pointer.offset. |
| 59 | const zeroField = field(0) |
| 60 | |
| 61 | // IsValid reports whether the field identifier is valid. |
| 62 | func (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. |
| 70 | type pointer struct { |
| 71 | p unsafe.Pointer |
| 72 | } |
| 73 | |
| 74 | // size of pointer |
| 75 | var ptrSize = unsafe.Sizeof(uintptr(0)) |
| 76 | |
| 77 | // toPointer converts an interface of pointer type to a pointer |
| 78 | // that points to the same target. |
| 79 | func 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. |
| 88 | func 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. |
| 106 | func 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. |
| 112 | func (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 | |
| 123 | func (p pointer) isNil() bool { |
| 124 | return p.p == nil |
| 125 | } |
| 126 | |
| 127 | func (p pointer) toInt64() *int64 { |
| 128 | return (*int64)(p.p) |
| 129 | } |
| 130 | func (p pointer) toInt64Ptr() **int64 { |
| 131 | return (**int64)(p.p) |
| 132 | } |
| 133 | func (p pointer) toInt64Slice() *[]int64 { |
| 134 | return (*[]int64)(p.p) |
| 135 | } |
| 136 | func (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 | */ |
| 149 | func (p pointer) getInt32Ptr() *int32 { |
| 150 | return *(**int32)(p.p) |
| 151 | } |
| 152 | func (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. |
| 159 | func (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. |
| 166 | func (p pointer) setInt32Slice(v []int32) { |
| 167 | *(*[]int32)(p.p) = v |
| 168 | } |
| 169 | |
| 170 | // TODO: Can we get rid of appendInt32Slice and use setInt32Slice instead? |
| 171 | func (p pointer) appendInt32Slice(v int32) { |
| 172 | s := (*[]int32)(p.p) |
| 173 | *s = append(*s, v) |
| 174 | } |
| 175 | |
| 176 | func (p pointer) toUint64() *uint64 { |
| 177 | return (*uint64)(p.p) |
| 178 | } |
| 179 | func (p pointer) toUint64Ptr() **uint64 { |
| 180 | return (**uint64)(p.p) |
| 181 | } |
| 182 | func (p pointer) toUint64Slice() *[]uint64 { |
| 183 | return (*[]uint64)(p.p) |
| 184 | } |
| 185 | func (p pointer) toUint32() *uint32 { |
| 186 | return (*uint32)(p.p) |
| 187 | } |
| 188 | func (p pointer) toUint32Ptr() **uint32 { |
| 189 | return (**uint32)(p.p) |
| 190 | } |
| 191 | func (p pointer) toUint32Slice() *[]uint32 { |
| 192 | return (*[]uint32)(p.p) |
| 193 | } |
| 194 | func (p pointer) toBool() *bool { |
| 195 | return (*bool)(p.p) |
| 196 | } |
| 197 | func (p pointer) toBoolPtr() **bool { |
| 198 | return (**bool)(p.p) |
| 199 | } |
| 200 | func (p pointer) toBoolSlice() *[]bool { |
| 201 | return (*[]bool)(p.p) |
| 202 | } |
| 203 | func (p pointer) toFloat64() *float64 { |
| 204 | return (*float64)(p.p) |
| 205 | } |
| 206 | func (p pointer) toFloat64Ptr() **float64 { |
| 207 | return (**float64)(p.p) |
| 208 | } |
| 209 | func (p pointer) toFloat64Slice() *[]float64 { |
| 210 | return (*[]float64)(p.p) |
| 211 | } |
| 212 | func (p pointer) toFloat32() *float32 { |
| 213 | return (*float32)(p.p) |
| 214 | } |
| 215 | func (p pointer) toFloat32Ptr() **float32 { |
| 216 | return (**float32)(p.p) |
| 217 | } |
| 218 | func (p pointer) toFloat32Slice() *[]float32 { |
| 219 | return (*[]float32)(p.p) |
| 220 | } |
| 221 | func (p pointer) toString() *string { |
| 222 | return (*string)(p.p) |
| 223 | } |
| 224 | func (p pointer) toStringPtr() **string { |
| 225 | return (**string)(p.p) |
| 226 | } |
| 227 | func (p pointer) toStringSlice() *[]string { |
| 228 | return (*[]string)(p.p) |
| 229 | } |
| 230 | func (p pointer) toBytes() *[]byte { |
| 231 | return (*[]byte)(p.p) |
| 232 | } |
| 233 | func (p pointer) toBytesSlice() *[][]byte { |
| 234 | return (*[][]byte)(p.p) |
| 235 | } |
| 236 | func (p pointer) toExtensions() *XXX_InternalExtensions { |
| 237 | return (*XXX_InternalExtensions)(p.p) |
| 238 | } |
| 239 | func (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. |
| 246 | func (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. |
| 255 | func (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. |
| 262 | func (p pointer) getPointer() pointer { |
| 263 | return pointer{p: *(*unsafe.Pointer)(p.p)} |
| 264 | } |
| 265 | |
| 266 | // setPointer stores the pointer q at p. |
| 267 | func (p pointer) setPointer(q pointer) { |
| 268 | *(*unsafe.Pointer)(p.p) = q.p |
| 269 | } |
| 270 | |
| 271 | // append q to the slice pointed to by p. |
| 272 | func (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. |
| 279 | func (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. |
| 286 | func (p pointer) asPointerTo(t reflect.Type) reflect.Value { |
| 287 | return reflect.NewAt(t, p.p) |
| 288 | } |
| 289 | |
| 290 | func atomicLoadUnmarshalInfo(p **unmarshalInfo) *unmarshalInfo { |
| 291 | return (*unmarshalInfo)(atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(p)))) |
| 292 | } |
| 293 | func atomicStoreUnmarshalInfo(p **unmarshalInfo, v *unmarshalInfo) { |
| 294 | atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(p)), unsafe.Pointer(v)) |
| 295 | } |
| 296 | func atomicLoadMarshalInfo(p **marshalInfo) *marshalInfo { |
| 297 | return (*marshalInfo)(atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(p)))) |
| 298 | } |
| 299 | func atomicStoreMarshalInfo(p **marshalInfo, v *marshalInfo) { |
| 300 | atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(p)), unsafe.Pointer(v)) |
| 301 | } |
| 302 | func atomicLoadMergeInfo(p **mergeInfo) *mergeInfo { |
| 303 | return (*mergeInfo)(atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(p)))) |
| 304 | } |
| 305 | func atomicStoreMergeInfo(p **mergeInfo, v *mergeInfo) { |
| 306 | atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(p)), unsafe.Pointer(v)) |
| 307 | } |
| 308 | func atomicLoadDiscardInfo(p **discardInfo) *discardInfo { |
| 309 | return (*discardInfo)(atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(p)))) |
| 310 | } |
| 311 | func atomicStoreDiscardInfo(p **discardInfo, v *discardInfo) { |
| 312 | atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(p)), unsafe.Pointer(v)) |
| 313 | } |