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
29package proto
30
31import (
32	"fmt"
33	"io"
34)
35
36func 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}
120