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
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
|
package docker
import (
"archive/tar"
"compress/gzip"
"fmt"
"io"
"io/ioutil"
"os"
"path"
"strings"
"github.com/wagoodman/dive/dive/filetree"
"github.com/wagoodman/dive/dive/image"
)
type ImageArchive struct {
manifest manifest
config config
layerMap map[string]*filetree.FileTree
}
func NewImageArchive(tarFile io.ReadCloser) (*ImageArchive, error) {
img := &ImageArchive{
layerMap: make(map[string]*filetree.FileTree),
}
tarReader := tar.NewReader(tarFile)
// store discovered json files in a map so we can read the image in one pass
jsonFiles := make(map[string][]byte)
var currentLayer uint
for {
header, err := tarReader.Next()
if err == io.EOF {
break
}
if err != nil {
fmt.Println(err)
os.Exit(1)
}
name := header.Name
// some layer tars can be relative layer symlinks to other layer tars
if header.Typeflag == tar.TypeSymlink || header.Typeflag == tar.TypeReg {
if strings.HasSuffix(name, ".tar") {
currentLayer++
layerReader := tar.NewReader(tarReader)
tree, err := processLayerTar(name, layerReader)
if err != nil {
return img, err
}
// add the layer to the image
img.layerMap[tree.Name] = tree
} else if strings.HasSuffix(name, ".tar.gz") || strings.HasSuffix(name, "tgz") {
currentLayer++
// Add gzip reader
gz, err := gzip.NewReader(tarReader)
if err != nil {
return img, err
}
// Add tar reader
layerReader := tar.NewReader(gz)
// Process layer
tree, err := processLayerTar(name, layerReader)
if err != nil {
return img, err
}
// add the layer to the image
img.layerMap[tree.Name] = tree
} else if strings.HasSuffix(name, ".json") || strings.HasPrefix(name, "sha256:") {
fileBuffer, err := ioutil.ReadAll(tarReader)
if err != nil {
return img, err
}
jsonFiles[name] = fileBuffer
}
}
}
manifestContent, exists := jsonFiles["manifest.json"]
if !exists {
return img, fmt.Errorf("could not find image manifest")
}
img.manifest = newManifest(manifestContent)
configContent, exists := jsonFiles[img.manifest.ConfigPath]
if !exists {
return img, fmt.Errorf("could not find image config")
}
img.config = newConfig(configContent)
return img, nil
}
func processLayerTar(name string, reader *tar.Reader) (*filetree.FileTree, error) {
tree := filetree.NewFileTree()
tree.Name = name
fileInfos, err := getFileList(reader)
if err != nil {
return nil, err
}
for _, element := range fileInfos {
tree.FileSize += uint64(element.Size)
_, _, err := tree.AddPath(element.Path, element)
if err != nil {
return nil, err
}
}
return tree, nil
}
func getFileList(tarReader *tar.Reader) ([]filetree.FileInfo, error) {
var files []filetree.FileInfo
for {
header, err := tarReader.Next()
if err == io.EOF {
break
} else if err != nil {
return nil, err
}
// always ensure relative path notations are not parsed as part of the filename
name := path.Clean(header.Name)
if name == "." {
continue
}
switch header.Typeflag {
case tar.TypeXGlobalHeader:
return nil, fmt.Errorf("unexptected tar file: (XGlobalHeader): type=%v name=%s", header.Typeflag, name)
case tar.TypeXHeader:
return nil, fmt.Errorf("unexptected tar file (XHeader): type=%v name=%s", header.Typeflag, name)
default:
files = append(files, filetree.NewFileInfoFromTarHeader(tarReader, header, name))
}
}
return files, nil
}
func (img *ImageArchive) ToImage() (*image.Image, error) {
trees := make([]*filetree.FileTree, 0)
// build the content tree
for _, treeName := range img.manifest.LayerTarPaths {
tr, exists := img.layerMap[treeName]
if exists {
trees = append(trees, tr)
continue
}
return nil, fmt.Errorf("could not find '%s' in parsed layers", treeName)
}
// build the layers array
layers := make([]*image.Layer, 0)
// note that the engineResolver config stores images in reverse chronological order, so iterate backwards through layers
// as you iterate chronologically through history (ignoring history items that have no layer contents)
// Note: history is not required metadata in a docker image!
histIdx := 0
for idx, tree := range trees {
// ignore empty layers, we are only observing layers with content
historyObj := historyEntry{
CreatedBy: "(missing)",
}
for nextHistIdx := histIdx; nextHistIdx < len(img.config.History); nextHistIdx++ {
if !img.config.History[nextHistIdx].EmptyLayer {
histIdx = nextHistIdx
break
}
}
if histIdx < len(img.config.History) && !img.config.History[histIdx].EmptyLayer {
historyObj = img.config.History[histIdx]
histIdx++
}
historyObj.Size = tree.FileSize
dockerLayer := layer{
history: historyObj,
index: idx,
tree: tree,
}
layers = append(layers, dockerLayer.ToLayer())
}
return &image.Image{
Trees: trees,
Layers: layers,
}, nil
}
|
