vendor/github.com/golang/protobuf/proto/decode.go

   1 // Go support for Protocol Buffers - Google's data interchange format
   2 //
   3 // Copyright 2010 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 package proto
  33
  34 /*
  35  * Routines for decoding protocol buffer data to construct in-memory representations.
  36  */
  37
  38 import (
  39         "errors"
  40         "fmt"
  41         "io"
  42 )
  43
  44 // errOverflow is returned when an integer is too large to be represented.
  45 var errOverflow = errors.New("proto: integer overflow")
  46
  47 // ErrInternalBadWireType is returned by generated code when an incorrect
  48 // wire type is encountered. It does not get returned to user code.
  49 var ErrInternalBadWireType = errors.New("proto: internal error: bad wiretype for oneof")
  50
  51 // DecodeVarint reads a varint-encoded integer from the slice.
  52 // It returns the integer and the number of bytes consumed, or
  53 // zero if there is not enough.
  54 // This is the format for the
  55 // int32, int64, uint32, uint64, bool, and enum
  56 // protocol buffer types.
  57 func DecodeVarint(buf []byte) (x uint64, n int) {
  58         for shift := uint(0); shift < 64; shift += 7 {
  59                 if n >= len(buf) {
  60                         return 0, 0
  61                 }
  62                 b := uint64(buf[n])
  63                 n++
  64                 x |= (b & 0x7F) << shift
  65                 if (b & 0x80) == 0 {
  66                         return x, n
  67                 }
  68         }
  69
  70         // The number is too large to represent in a 64-bit value.
  71         return 0, 0
  72 }
  73
  74 func (p *Buffer) decodeVarintSlow() (x uint64, err error) {
  75         i := p.index
  76         l := len(p.buf)
  77
  78         for shift := uint(0); shift < 64; shift += 7 {
  79                 if i >= l {
  80                         err = io.ErrUnexpectedEOF
  81                         return
  82                 }
  83                 b := p.buf[i]
  84                 i++
  85                 x |= (uint64(b) & 0x7F) << shift
  86                 if b < 0x80 {
  87                         p.index = i
  88                         return
  89                 }
  90         }
  91
  92         // The number is too large to represent in a 64-bit value.
  93         err = errOverflow
  94         return
  95 }
  96
  97 // DecodeVarint reads a varint-encoded integer from the Buffer.
  98 // This is the format for the
  99 // int32, int64, uint32, uint64, bool, and enum
 100 // protocol buffer types.
 101 func (p *Buffer) DecodeVarint() (x uint64, err error) {
 102         i := p.index
 103         buf := p.buf
 104
 105         if i >= len(buf) {
 106                 return 0, io.ErrUnexpectedEOF
 107         } else if buf[i] < 0x80 {
 108                 p.index++
 109                 return uint64(buf[i]), nil
 110         } else if len(buf)-i < 10 {
 111                 return p.decodeVarintSlow()
 112         }
 113
 114         var b uint64
 115         // we already checked the first byte
 116         x = uint64(buf[i]) - 0x80
 117         i++
 118
 119         b = uint64(buf[i])
 120         i++
 121         x += b << 7
 122         if b&0x80 == 0 {
 123                 goto done
 124         }
 125         x -= 0x80 << 7
 126
 127         b = uint64(buf[i])
 128         i++
 129         x += b << 14
 130         if b&0x80 == 0 {
 131                 goto done
 132         }
 133         x -= 0x80 << 14
 134
 135         b = uint64(buf[i])
 136         i++
 137         x += b << 21
 138         if b&0x80 == 0 {
 139                 goto done
 140         }
 141         x -= 0x80 << 21
 142
 143         b = uint64(buf[i])
 144         i++
 145         x += b << 28
 146         if b&0x80 == 0 {
 147                 goto done
 148         }
 149         x -= 0x80 << 28
 150
 151         b = uint64(buf[i])
 152         i++
 153         x += b << 35
 154         if b&0x80 == 0 {
 155                 goto done
 156         }
 157         x -= 0x80 << 35
 158
 159         b = uint64(buf[i])
 160         i++
 161         x += b << 42
 162         if b&0x80 == 0 {
 163                 goto done
 164         }
 165         x -= 0x80 << 42
 166
 167         b = uint64(buf[i])
 168         i++
 169         x += b << 49
 170         if b&0x80 == 0 {
 171                 goto done
 172         }
 173         x -= 0x80 << 49
 174
 175         b = uint64(buf[i])
 176         i++
 177         x += b << 56
 178         if b&0x80 == 0 {
 179                 goto done
 180         }
 181         x -= 0x80 << 56
 182
 183         b = uint64(buf[i])
 184         i++
 185         x += b << 63
 186         if b&0x80 == 0 {
 187                 goto done
 188         }
 189
 190         return 0, errOverflow
 191
 192 done:
 193         p.index = i
 194         return x, nil
 195 }
 196
 197 // DecodeFixed64 reads a 64-bit integer from the Buffer.
 198 // This is the format for the
 199 // fixed64, sfixed64, and double protocol buffer types.
 200 func (p *Buffer) DecodeFixed64() (x uint64, err error) {
 201         // x, err already 0
 202         i := p.index + 8
 203         if i < 0 || i > len(p.buf) {
 204                 err = io.ErrUnexpectedEOF
 205                 return
 206         }
 207         p.index = i
 208
 209         x = uint64(p.buf[i-8])
 210         x |= uint64(p.buf[i-7]) << 8
 211         x |= uint64(p.buf[i-6]) << 16
 212         x |= uint64(p.buf[i-5]) << 24
 213         x |= uint64(p.buf[i-4]) << 32
 214         x |= uint64(p.buf[i-3]) << 40
 215         x |= uint64(p.buf[i-2]) << 48
 216         x |= uint64(p.buf[i-1]) << 56
 217         return
 218 }
 219
 220 // DecodeFixed32 reads a 32-bit integer from the Buffer.
 221 // This is the format for the
 222 // fixed32, sfixed32, and float protocol buffer types.
 223 func (p *Buffer) DecodeFixed32() (x uint64, err error) {
 224         // x, err already 0
 225         i := p.index + 4
 226         if i < 0 || i > len(p.buf) {
 227                 err = io.ErrUnexpectedEOF
 228                 return
 229         }
 230         p.index = i
 231
 232         x = uint64(p.buf[i-4])
 233         x |= uint64(p.buf[i-3]) << 8
 234         x |= uint64(p.buf[i-2]) << 16
 235         x |= uint64(p.buf[i-1]) << 24
 236         return
 237 }
 238
 239 // DecodeZigzag64 reads a zigzag-encoded 64-bit integer
 240 // from the Buffer.
 241 // This is the format used for the sint64 protocol buffer type.
 242 func (p *Buffer) DecodeZigzag64() (x uint64, err error) {
 243         x, err = p.DecodeVarint()
 244         if err != nil {
 245                 return
 246         }
 247         x = (x >> 1) ^ uint64((int64(x&1)<<63)>>63)
 248         return
 249 }
 250
 251 // DecodeZigzag32 reads a zigzag-encoded 32-bit integer
 252 // from  the Buffer.
 253 // This is the format used for the sint32 protocol buffer type.
 254 func (p *Buffer) DecodeZigzag32() (x uint64, err error) {
 255         x, err = p.DecodeVarint()
 256         if err != nil {
 257                 return
 258         }
 259         x = uint64((uint32(x) >> 1) ^ uint32((int32(x&1)<<31)>>31))
 260         return
 261 }
 262
 263 // DecodeRawBytes reads a count-delimited byte buffer from the Buffer.
 264 // This is the format used for the bytes protocol buffer
 265 // type and for embedded messages.
 266 func (p *Buffer) DecodeRawBytes(alloc bool) (buf []byte, err error) {
 267         n, err := p.DecodeVarint()
 268         if err != nil {
 269                 return nil, err
 270         }
 271
 272         nb := int(n)
 273         if nb < 0 {
 274                 return nil, fmt.Errorf("proto: bad byte length %d", nb)
 275         }
 276         end := p.index + nb
 277         if end < p.index || end > len(p.buf) {
 278                 return nil, io.ErrUnexpectedEOF
 279         }
 280
 281         if !alloc {
 282                 // todo: check if can get more uses of alloc=false
 283                 buf = p.buf[p.index:end]
 284                 p.index += nb
 285                 return
 286         }
 287
 288         buf = make([]byte, nb)
 289         copy(buf, p.buf[p.index:])
 290         p.index += nb
 291         return
 292 }
 293
 294 // DecodeStringBytes reads an encoded string from the Buffer.
 295 // This is the format used for the proto2 string type.
 296 func (p *Buffer) DecodeStringBytes() (s string, err error) {
 297         buf, err := p.DecodeRawBytes(false)
 298         if err != nil {
 299                 return
 300         }
 301         return string(buf), nil
 302 }
 303
 304 // Unmarshaler is the interface representing objects that can
 305 // unmarshal themselves.  The argument points to data that may be
 306 // overwritten, so implementations should not keep references to the
 307 // buffer.
 308 // Unmarshal implementations should not clear the receiver.
 309 // Any unmarshaled data should be merged into the receiver.
 310 // Callers of Unmarshal that do not want to retain existing data
 311 // should Reset the receiver before calling Unmarshal.
 312 type Unmarshaler interface {
 313         Unmarshal([]byte) error
 314 }
 315
 316 // newUnmarshaler is the interface representing objects that can
 317 // unmarshal themselves. The semantics are identical to Unmarshaler.
 318 //
 319 // This exists to support protoc-gen-go generated messages.
 320 // The proto package will stop type-asserting to this interface in the future.
 321 //
 322 // DO NOT DEPEND ON THIS.
 323 type newUnmarshaler interface {
 324         XXX_Unmarshal([]byte) error
 325 }
 326
 327 // Unmarshal parses the protocol buffer representation in buf and places the
 328 // decoded result in pb.  If the struct underlying pb does not match
 329 // the data in buf, the results can be unpredictable.
 330 //
 331 // Unmarshal resets pb before starting to unmarshal, so any
 332 // existing data in pb is always removed. Use UnmarshalMerge
 333 // to preserve and append to existing data.
 334 func Unmarshal(buf []byte, pb Message) error {
 335         pb.Reset()
 336         if u, ok := pb.(newUnmarshaler); ok {
 337                 return u.XXX_Unmarshal(buf)
 338         }
 339         if u, ok := pb.(Unmarshaler); ok {
 340                 return u.Unmarshal(buf)
 341         }
 342         return NewBuffer(buf).Unmarshal(pb)
 343 }
 344
 345 // UnmarshalMerge parses the protocol buffer representation in buf and
 346 // writes the decoded result to pb.  If the struct underlying pb does not match
 347 // the data in buf, the results can be unpredictable.
 348 //
 349 // UnmarshalMerge merges into existing data in pb.
 350 // Most code should use Unmarshal instead.
 351 func UnmarshalMerge(buf []byte, pb Message) error {
 352         if u, ok := pb.(newUnmarshaler); ok {
 353                 return u.XXX_Unmarshal(buf)
 354         }
 355         if u, ok := pb.(Unmarshaler); ok {
 356                 // NOTE: The history of proto have unfortunately been inconsistent
 357                 // whether Unmarshaler should or should not implicitly clear itself.
 358                 // Some implementations do, most do not.
 359                 // Thus, calling this here may or may not do what people want.
 360                 //
 361                 // See https://github.com/golang/protobuf/issues/424
 362                 return u.Unmarshal(buf)
 363         }
 364         return NewBuffer(buf).Unmarshal(pb)
 365 }
 366
 367 // DecodeMessage reads a count-delimited message from the Buffer.
 368 func (p *Buffer) DecodeMessage(pb Message) error {
 369         enc, err := p.DecodeRawBytes(false)
 370         if err != nil {
 371                 return err
 372         }
 373         return NewBuffer(enc).Unmarshal(pb)
 374 }
 375
 376 // DecodeGroup reads a tag-delimited group from the Buffer.
 377 // StartGroup tag is already consumed. This function consumes
 378 // EndGroup tag.
 379 func (p *Buffer) DecodeGroup(pb Message) error {
 380         b := p.buf[p.index:]
 381         x, y := findEndGroup(b)
 382         if x < 0 {
 383                 return io.ErrUnexpectedEOF
 384         }
 385         err := Unmarshal(b[:x], pb)
 386         p.index += y
 387         return err
 388 }
 389
 390 // Unmarshal parses the protocol buffer representation in the
 391 // Buffer and places the decoded result in pb.  If the struct
 392 // underlying pb does not match the data in the buffer, the results can be
 393 // unpredictable.
 394 //
 395 // Unlike proto.Unmarshal, this does not reset pb before starting to unmarshal.
 396 func (p *Buffer) Unmarshal(pb Message) error {
 397         // If the object can unmarshal itself, let it.
 398         if u, ok := pb.(newUnmarshaler); ok {
 399                 err := u.XXX_Unmarshal(p.buf[p.index:])
 400                 p.index = len(p.buf)
 401                 return err
 402         }
 403         if u, ok := pb.(Unmarshaler); ok {
 404                 // NOTE: The history of proto have unfortunately been inconsistent
 405                 // whether Unmarshaler should or should not implicitly clear itself.
 406                 // Some implementations do, most do not.
 407                 // Thus, calling this here may or may not do what people want.
 408                 //
 409                 // See https://github.com/golang/protobuf/issues/424
 410                 err := u.Unmarshal(p.buf[p.index:])
 411                 p.index = len(p.buf)
 412                 return err
 413         }
 414
 415         // Slow workaround for messages that aren't Unmarshalers.
 416         // This includes some hand-coded .pb.go files and
 417         // bootstrap protos.
 418         // TODO: fix all of those and then add Unmarshal to
 419         // the Message interface. Then:
 420         // The cast above and code below can be deleted.
 421         // The old unmarshaler can be deleted.
 422         // Clients can call Unmarshal directly (can already do that, actually).
 423         var info InternalMessageInfo
 424         err := info.Unmarshal(pb, p.buf[p.index:])
 425         p.index = len(p.buf)
 426         return err
 427 }