undocker/rootfs/rootfs_test.go

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package rootfs
import (
"archive/tar"
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"bytes"
"encoding/json"
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"testing"
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"github.com/motiejus/code/undocker/internal/tartest"
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"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
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)
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type (
file = tartest.File
dir = tartest.Dir
hardlink = tartest.Hardlink
extractable = tartest.Extractable
tarball = tartest.Tarball
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)
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func TestRootFS(t *testing.T) {
layer0 := tarball{
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dir{Name: "/", Uid: 0},
file{Name: "/file", Uid: 0, Contents: bytes.NewBufferString("from 0")},
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}
layer1 := tarball{
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file{Name: "/file", Uid: 1, Contents: bytes.NewBufferString("from 1")},
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}
layer2 := tarball{
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dir{Name: "/", Uid: 2},
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}
tests := []struct {
name string
image tarball
want []extractable
wantErr string
}{
{
name: "empty tarball",
image: tarball{manifest{}},
want: []extractable{},
},
{
name: "missing layer",
image: tarball{manifest{"layer0/layer.tar"}},
wantErr: "bad or missing manifest.json",
},
{
name: "basic file overwrite, layer order mixed",
image: tarball{
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file{Name: "layer1/layer.tar", Contents: layer1.Buffer()},
file{Name: "layer0/layer.tar", Contents: layer0.Buffer()},
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manifest{"layer0/layer.tar", "layer1/layer.tar"},
},
want: []extractable{
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dir{Name: "/", Uid: 0},
file{Name: "/file", Uid: 1, Contents: bytes.NewBufferString("from 1")},
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},
},
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{
name: "overwrite file with hardlink",
image: tarball{
file{Name: "layer0/layer.tar", Contents: tarball{
file{Name: "a"},
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}.Buffer()},
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file{Name: "layer1/layer.tar", Contents: tarball{
hardlink{Name: "a"},
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}.Buffer()},
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manifest{"layer0/layer.tar", "layer1/layer.tar"},
},
want: []extractable{
hardlink{Name: "a"},
},
},
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{
name: "directory overwrite retains original dir",
image: tarball{
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file{Name: "layer2/layer.tar", Contents: layer2.Buffer()},
file{Name: "layer0/layer.tar", Contents: layer0.Buffer()},
file{Name: "layer1/layer.tar", Contents: layer1.Buffer()},
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manifest{"layer0/layer.tar", "layer1/layer.tar", "layer2/layer.tar"},
},
want: []extractable{
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dir{Name: "/", Uid: 0},
file{Name: "/file", Uid: 1, Contents: bytes.NewBufferString("from 1")},
dir{Name: "/", Uid: 2},
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},
},
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{
name: "simple whiteout",
image: tarball{
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file{Name: "layer0/layer.tar", Contents: tarball{
file{Name: "filea"},
file{Name: "fileb"},
dir{Name: "dira"},
dir{Name: "dirb"},
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}.Buffer()},
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file{Name: "layer1/layer.tar", Contents: tarball{
hardlink{Name: ".wh.filea"},
hardlink{Name: ".wh.dira"},
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}.Buffer()},
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manifest{"layer0/layer.tar", "layer1/layer.tar"},
},
want: []extractable{
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file{Name: "fileb"},
dir{Name: "dirb"},
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},
},
{
name: "whiteout with override",
image: tarball{
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file{Name: "layer0/layer.tar", Contents: tarball{
file{Name: "file", Contents: bytes.NewBufferString("from 0")},
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}.Buffer()},
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file{Name: "layer1/layer.tar", Contents: tarball{
hardlink{Name: ".wh.file"},
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}.Buffer()},
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file{Name: "layer2/layer.tar", Contents: tarball{
file{Name: "file", Contents: bytes.NewBufferString("from 3")},
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}.Buffer()},
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manifest{
"layer0/layer.tar",
"layer1/layer.tar",
"layer2/layer.tar",
},
},
want: []extractable{
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file{Name: "file", Contents: bytes.NewBufferString("from 3")},
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},
},
{
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name: "directories do not whiteout",
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image: tarball{
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file{Name: "layer0/layer.tar", Contents: tarball{
dir{Name: "dir"},
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}.Buffer()},
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file{Name: "layer1/layer.tar", Contents: tarball{
dir{Name: ".wh.dir"},
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}.Buffer()},
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manifest{"layer0/layer.tar", "layer1/layer.tar"},
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},
want: []extractable{
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dir{Name: "dir"},
dir{Name: ".wh.dir"},
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},
},
{
name: "simple readdir whiteout",
image: tarball{
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file{Name: "layer0/layer.tar", Contents: tarball{
dir{Name: "a"},
file{Name: "a/filea"},
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}.Buffer()},
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file{Name: "layer1/layer.tar", Contents: tarball{
dir{Name: "a"},
file{Name: "a/fileb"},
hardlink{Name: "a/.wh..wh..opq"},
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}.Buffer()},
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manifest{"layer0/layer.tar", "layer1/layer.tar"},
},
want: []extractable{
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dir{Name: "a"},
file{Name: "a/fileb"},
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},
},
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}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
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in := bytes.NewReader(tt.image.Buffer().Bytes())
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out := bytes.Buffer{}
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err := New(in).WriteTo(&out)
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if tt.wantErr != "" {
assert.EqualError(t, err, tt.wantErr)
return
}
require.NoError(t, err)
got := tartest.Extract(t, &out)
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assert.Equal(t, tt.want, got)
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})
}
}
// Helpers
type (
manifest []string
)
func (m manifest) Tar(tw *tar.Writer) error {
b, err := json.Marshal(dockerManifestJSON{{Layers: m}})
if err != nil {
return err
}
return file{
Name: "manifest.json",
Contents: bytes.NewBuffer(b),
}.Tar(tw)
}