forked from cloudfoundry-attic/garden-linux
/
versioning.go
132 lines (111 loc) · 3.48 KB
/
versioning.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
package tarsum
import (
"errors"
"sort"
"strconv"
"strings"
"github.com/docker/docker/vendor/src/code.google.com/p/go/src/pkg/archive/tar"
)
// versioning of the TarSum algorithm
// based on the prefix of the hash used
// i.e. "tarsum+sha256:e58fcf7418d4390dec8e8fb69d88c06ec07039d651fedd3aa72af9972e7d046b"
type Version int
// Prefix of "tarsum"
const (
Version0 Version = iota
Version1
// NOTE: this variable will be either the latest or an unsettled next-version of the TarSum calculation
VersionDev
)
// Get a list of all known tarsum Version
func GetVersions() []Version {
v := []Version{}
for k := range tarSumVersions {
v = append(v, k)
}
return v
}
var tarSumVersions = map[Version]string{
Version0: "tarsum",
Version1: "tarsum.v1",
VersionDev: "tarsum.dev",
}
func (tsv Version) String() string {
return tarSumVersions[tsv]
}
// GetVersionFromTarsum returns the Version from the provided string
func GetVersionFromTarsum(tarsum string) (Version, error) {
tsv := tarsum
if strings.Contains(tarsum, "+") {
tsv = strings.SplitN(tarsum, "+", 2)[0]
}
for v, s := range tarSumVersions {
if s == tsv {
return v, nil
}
}
return -1, ErrNotVersion
}
// Errors that may be returned by functions in this package
var (
ErrNotVersion = errors.New("string does not include a TarSum Version")
ErrVersionNotImplemented = errors.New("TarSum Version is not yet implemented")
)
// tarHeaderSelector is the interface which different versions
// of tarsum should use for selecting and ordering tar headers
// for each item in the archive.
type tarHeaderSelector interface {
selectHeaders(h *tar.Header) (orderedHeaders [][2]string)
}
type tarHeaderSelectFunc func(h *tar.Header) (orderedHeaders [][2]string)
func (f tarHeaderSelectFunc) selectHeaders(h *tar.Header) (orderedHeaders [][2]string) {
return f(h)
}
func v0TarHeaderSelect(h *tar.Header) (orderedHeaders [][2]string) {
return [][2]string{
{"name", h.Name},
{"mode", strconv.Itoa(int(h.Mode))},
{"uid", strconv.Itoa(h.Uid)},
{"gid", strconv.Itoa(h.Gid)},
{"size", strconv.Itoa(int(h.Size))},
{"mtime", strconv.Itoa(int(h.ModTime.UTC().Unix()))},
{"typeflag", string([]byte{h.Typeflag})},
{"linkname", h.Linkname},
{"uname", h.Uname},
{"gname", h.Gname},
{"devmajor", strconv.Itoa(int(h.Devmajor))},
{"devminor", strconv.Itoa(int(h.Devminor))},
}
}
func v1TarHeaderSelect(h *tar.Header) (orderedHeaders [][2]string) {
// Get extended attributes.
xAttrKeys := make([]string, len(h.Xattrs))
for k := range h.Xattrs {
xAttrKeys = append(xAttrKeys, k)
}
sort.Strings(xAttrKeys)
// Make the slice with enough capacity to hold the 11 basic headers
// we want from the v0 selector plus however many xattrs we have.
orderedHeaders = make([][2]string, 0, 11+len(xAttrKeys))
// Copy all headers from v0 excluding the 'mtime' header (the 5th element).
v0headers := v0TarHeaderSelect(h)
orderedHeaders = append(orderedHeaders, v0headers[0:5]...)
orderedHeaders = append(orderedHeaders, v0headers[6:]...)
// Finally, append the sorted xattrs.
for _, k := range xAttrKeys {
orderedHeaders = append(orderedHeaders, [2]string{k, h.Xattrs[k]})
}
return
}
var registeredHeaderSelectors = map[Version]tarHeaderSelectFunc{
Version0: v0TarHeaderSelect,
Version1: v1TarHeaderSelect,
VersionDev: v1TarHeaderSelect,
}
func getTarHeaderSelector(v Version) (tarHeaderSelector, error) {
headerSelector, ok := registeredHeaderSelectors[v]
if !ok {
return nil, ErrVersionNotImplemented
}
return headerSelector, nil
}