github.com/gogo/protobuf@v1.3.2/proto/skip_gogo.go (about)

     1  // Protocol Buffers for Go with Gadgets
     2  //
     3  // Copyright (c) 2013, The GoGo Authors. All rights reserved.
     4  // http://github.com/gogo/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  //
    17  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    18  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    19  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    20  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    21  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    22  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
    23  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    24  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
    25  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    26  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
    27  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
    28  
    29  package proto
    30  
    31  import (
    32  	"fmt"
    33  	"io"
    34  )
    35  
    36  func Skip(data []byte) (n int, err error) {
    37  	l := len(data)
    38  	index := 0
    39  	for index < l {
    40  		var wire uint64
    41  		for shift := uint(0); ; shift += 7 {
    42  			if index >= l {
    43  				return 0, io.ErrUnexpectedEOF
    44  			}
    45  			b := data[index]
    46  			index++
    47  			wire |= (uint64(b) & 0x7F) << shift
    48  			if b < 0x80 {
    49  				break
    50  			}
    51  		}
    52  		wireType := int(wire & 0x7)
    53  		switch wireType {
    54  		case 0:
    55  			for {
    56  				if index >= l {
    57  					return 0, io.ErrUnexpectedEOF
    58  				}
    59  				index++
    60  				if data[index-1] < 0x80 {
    61  					break
    62  				}
    63  			}
    64  			return index, nil
    65  		case 1:
    66  			index += 8
    67  			return index, nil
    68  		case 2:
    69  			var length int
    70  			for shift := uint(0); ; shift += 7 {
    71  				if index >= l {
    72  					return 0, io.ErrUnexpectedEOF
    73  				}
    74  				b := data[index]
    75  				index++
    76  				length |= (int(b) & 0x7F) << shift
    77  				if b < 0x80 {
    78  					break
    79  				}
    80  			}
    81  			index += length
    82  			return index, nil
    83  		case 3:
    84  			for {
    85  				var innerWire uint64
    86  				var start int = index
    87  				for shift := uint(0); ; shift += 7 {
    88  					if index >= l {
    89  						return 0, io.ErrUnexpectedEOF
    90  					}
    91  					b := data[index]
    92  					index++
    93  					innerWire |= (uint64(b) & 0x7F) << shift
    94  					if b < 0x80 {
    95  						break
    96  					}
    97  				}
    98  				innerWireType := int(innerWire & 0x7)
    99  				if innerWireType == 4 {
   100  					break
   101  				}
   102  				next, err := Skip(data[start:])
   103  				if err != nil {
   104  					return 0, err
   105  				}
   106  				index = start + next
   107  			}
   108  			return index, nil
   109  		case 4:
   110  			return index, nil
   111  		case 5:
   112  			index += 4
   113  			return index, nil
   114  		default:
   115  			return 0, fmt.Errorf("proto: illegal wireType %d", wireType)
   116  		}
   117  	}
   118  	panic("unreachable")
   119  }