motiejus/undocker
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add rootfstest

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This commit is contained in:
Motiejus Jakštys 2021-05-24 00:11:58 +03:00
parent eb9f4d5400
commit cb1045db17
5 changed files with 242 additions and 169 deletions
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1
rootfs/BUILD
View File

@ -20,6 +20,7 @@ go_test(
], ],
embed = [":go_default_library"], embed = [":go_default_library"],
deps = [ deps = [
"//src/undocker/rootfs/rootfstest:go_default_library",
"@com_github_stretchr_testify//assert:go_default_library", "@com_github_stretchr_testify//assert:go_default_library",
"@com_github_stretchr_testify//require:go_default_library", "@com_github_stretchr_testify//require:go_default_library",
], ],

229
rootfs/rootfs_test.go
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@ -1,28 +1,39 @@
package rootfs package rootfs
import ( import (
"archive/tar"
"bytes" "bytes"
"encoding/json"
"io"
"testing" "testing"
"github.com/motiejus/code/undocker/rootfs/rootfstest"
"github.com/stretchr/testify/assert" "github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require" "github.com/stretchr/testify/require"
) )
type (
file = rootfstest.File
dir = rootfstest.Dir
hardlink = rootfstest.Hardlink
manifest = rootfstest.Manifest
extractable = rootfstest.Extractable
tarball = rootfstest.Tarball
)
var (
extract = rootfstest.Extract
)
func TestRootFS(t *testing.T) { func TestRootFS(t *testing.T) {
layer0 := tarball{ layer0 := tarball{
dir{name: "/", uid: 0}, dir{Name: "/", Uid: 0},
file{name: "/file", uid: 0, contents: bytes.NewBufferString("from 0")}, file{Name: "/file", Uid: 0, Contents: bytes.NewBufferString("from 0")},
} }
layer1 := tarball{ layer1 := tarball{
file{name: "/file", uid: 1, contents: bytes.NewBufferString("from 1")}, file{Name: "/file", Uid: 1, Contents: bytes.NewBufferString("from 1")},
} }
layer2 := tarball{ layer2 := tarball{
dir{name: "/", uid: 2}, dir{Name: "/", Uid: 2},
} }
tests := []struct { tests := []struct {
@ -44,60 +55,60 @@ func TestRootFS(t *testing.T) {
{ {
name: "basic file overwrite, layer order mixed", name: "basic file overwrite, layer order mixed",
image: tarball{ image: tarball{
file{name: "layer1/layer.tar", contents: layer1}, file{Name: "layer1/layer.tar", Contents: layer1},
file{name: "layer0/layer.tar", contents: layer0}, file{Name: "layer0/layer.tar", Contents: layer0},
manifest{"layer0/layer.tar", "layer1/layer.tar"}, manifest{"layer0/layer.tar", "layer1/layer.tar"},
}, },
want: []extractable{ want: []extractable{
dir{name: "/", uid: 0}, dir{Name: "/", Uid: 0},
file{name: "/file", uid: 1, contents: bytes.NewBufferString("from 1")}, file{Name: "/file", Uid: 1, Contents: bytes.NewBufferString("from 1")},
}, },
}, },
{ {
name: "directory overwrite retains original dir", name: "directory overwrite retains original dir",
image: tarball{ image: tarball{
file{name: "layer2/layer.tar", contents: layer2}, file{Name: "layer2/layer.tar", Contents: layer2},
file{name: "layer0/layer.tar", contents: layer0}, file{Name: "layer0/layer.tar", Contents: layer0},
file{name: "layer1/layer.tar", contents: layer1}, file{Name: "layer1/layer.tar", Contents: layer1},
manifest{"layer0/layer.tar", "layer1/layer.tar", "layer2/layer.tar"}, manifest{"layer0/layer.tar", "layer1/layer.tar", "layer2/layer.tar"},
}, },
want: []extractable{ want: []extractable{
dir{name: "/", uid: 0}, dir{Name: "/", Uid: 0},
file{name: "/file", uid: 1, contents: bytes.NewBufferString("from 1")}, file{Name: "/file", Uid: 1, Contents: bytes.NewBufferString("from 1")},
dir{name: "/", uid: 2}, dir{Name: "/", Uid: 2},
}, },
}, },
{ {
name: "simple whiteout", name: "simple whiteout",
image: tarball{ image: tarball{
file{name: "layer0/layer.tar", contents: tarball{ file{Name: "layer0/layer.tar", Contents: tarball{
file{name: "filea"}, file{Name: "filea"},
file{name: "fileb"}, file{Name: "fileb"},
dir{name: "dira"}, dir{Name: "dira"},
dir{name: "dirb"}, dir{Name: "dirb"},
}}, }},
file{name: "layer1/layer.tar", contents: tarball{ file{Name: "layer1/layer.tar", Contents: tarball{
hardlink{name: ".wh.filea"}, hardlink{Name: ".wh.filea"},
hardlink{name: ".wh.dira"}, hardlink{Name: ".wh.dira"},
}}, }},
manifest{"layer0/layer.tar", "layer1/layer.tar"}, manifest{"layer0/layer.tar", "layer1/layer.tar"},
}, },
want: []extractable{ want: []extractable{
file{name: "fileb"}, file{Name: "fileb"},
dir{name: "dirb"}, dir{Name: "dirb"},
}, },
}, },
{ {
name: "whiteout with override", name: "whiteout with override",
image: tarball{ image: tarball{
file{name: "layer0/layer.tar", contents: tarball{ file{Name: "layer0/layer.tar", Contents: tarball{
file{name: "file", contents: bytes.NewBufferString("from 0")}, file{Name: "file", Contents: bytes.NewBufferString("from 0")},
}}, }},
file{name: "layer1/layer.tar", contents: tarball{ file{Name: "layer1/layer.tar", Contents: tarball{
hardlink{name: ".wh.file"}, hardlink{Name: ".wh.file"},
}}, }},
file{name: "layer2/layer.tar", contents: tarball{ file{Name: "layer2/layer.tar", Contents: tarball{
file{name: "file", contents: bytes.NewBufferString("from 3")}, file{Name: "file", Contents: bytes.NewBufferString("from 3")},
}}, }},
manifest{ manifest{
"layer0/layer.tar", "layer0/layer.tar",
@ -106,42 +117,42 @@ func TestRootFS(t *testing.T) {
}, },
}, },
want: []extractable{ want: []extractable{
file{name: "file", contents: bytes.NewBufferString("from 3")}, file{Name: "file", Contents: bytes.NewBufferString("from 3")},
}, },
}, },
{ {
name: "directories do not whiteout", name: "directories do not whiteout",
image: tarball{ image: tarball{
file{name: "layer0/layer.tar", contents: tarball{ file{Name: "layer0/layer.tar", Contents: tarball{
dir{name: "dir"}, dir{Name: "dir"},
}}, }},
file{name: "layer1/layer.tar", contents: tarball{ file{Name: "layer1/layer.tar", Contents: tarball{
dir{name: ".wh.dir"}, dir{Name: ".wh.dir"},
}}, }},
manifest{"layer0/layer.tar", "layer1/layer.tar"}, manifest{"layer0/layer.tar", "layer1/layer.tar"},
}, },
want: []extractable{ want: []extractable{
dir{name: "dir"}, dir{Name: "dir"},
dir{name: ".wh.dir"}, dir{Name: ".wh.dir"},
}, },
}, },
{ {
name: "simple readdir whiteout", name: "simple readdir whiteout",
image: tarball{ image: tarball{
file{name: "layer0/layer.tar", contents: tarball{ file{Name: "layer0/layer.tar", Contents: tarball{
dir{name: "a"}, dir{Name: "a"},
file{name: "a/filea"}, file{Name: "a/filea"},
}}, }},
file{name: "layer1/layer.tar", contents: tarball{ file{Name: "layer1/layer.tar", Contents: tarball{
dir{name: "a"}, dir{Name: "a"},
file{name: "a/fileb"}, file{Name: "a/fileb"},
hardlink{name: "a/.wh..wh..opq"}, hardlink{Name: "a/.wh..wh..opq"},
}}, }},
manifest{"layer0/layer.tar", "layer1/layer.tar"}, manifest{"layer0/layer.tar", "layer1/layer.tar"},
}, },
want: []extractable{ want: []extractable{
dir{name: "a"}, dir{Name: "a"},
file{name: "a/fileb"}, file{Name: "a/fileb"},
}, },
}, },
} }
@ -162,123 +173,3 @@ func TestRootFS(t *testing.T) {
}) })
} }
} }
// Helpers
type tarrer interface {
tar(*tar.Writer)
}
type byter interface {
Bytes() []byte
}
type tarball []tarrer
func (tb tarball) Bytes() []byte {
buf := bytes.Buffer{}
tw := tar.NewWriter(&buf)
for _, member := range tb {
member.tar(tw)
}
tw.Close()
return buf.Bytes()
}
// extractable is an empty interface for comparing extracted outputs in tests.
// Using that just to avoid the ugly `interface{}`.
type extractable interface{}
type dir struct {
name string
uid int
}
func (d dir) tar(tw *tar.Writer) {
hdr := &tar.Header{
Typeflag: tar.TypeDir,
Name: d.name,
Mode: 0644,
Uid: d.uid,
}
tw.WriteHeader(hdr)
}
type file struct {
name string
uid int
contents byter
}
func (f file) tar(tw *tar.Writer) {
var contentbytes []byte
if f.contents != nil {
contentbytes = f.contents.Bytes()
}
hdr := &tar.Header{
Typeflag: tar.TypeReg,
Name: f.name,
Mode: 0644,
Uid: f.uid,
Size: int64(len(contentbytes)),
}
tw.WriteHeader(hdr)
tw.Write(contentbytes)
}
type manifest []string
func (m manifest) tar(tw *tar.Writer) {
b, err := json.Marshal(dockerManifestJSON{{Layers: m}})
if err != nil {
panic("testerr")
}
file{
name: "manifest.json",
uid: 0,
contents: bytes.NewBuffer(b),
}.tar(tw)
}
type hardlink struct {
name string
uid int
}
func (h hardlink) tar(tw *tar.Writer) {
tw.WriteHeader(&tar.Header{
Typeflag: tar.TypeLink,
Name: h.name,
Mode: 0644,
Uid: h.uid,
})
}
func extract(t *testing.T, r io.Reader) []extractable {
t.Helper()
ret := []extractable{}
tr := tar.NewReader(r)
for {
hdr, err := tr.Next()
if err == io.EOF {
break
}
require.NoError(t, err)
var elem extractable
switch hdr.Typeflag {
case tar.TypeDir:
elem = dir{name: hdr.Name, uid: hdr.Uid}
case tar.TypeReg:
f := file{name: hdr.Name, uid: hdr.Uid}
if hdr.Size > 0 {
var buf bytes.Buffer
io.Copy(&buf, tr)
f.contents = &buf
}
elem = f
}
ret = append(ret, elem)
}
return ret
}

16
rootfs/rootfstest/BUILD Normal file
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@ -0,0 +1,16 @@
load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
go_library(
name = "go_default_library",
srcs = ["rootfstest.go"],
importpath = "github.com/motiejus/code/undocker/rootfs/rootfstest",
visibility = ["//visibility:public"],
deps = ["@com_github_stretchr_testify//require:go_default_library"],
)
go_test(
name = "go_default_test",
srcs = ["rootfstest_test.go"],
embed = [":go_default_library"],
deps = ["@com_github_stretchr_testify//assert:go_default_library"],
)

137
rootfs/rootfstest/rootfstest.go Normal file
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@ -0,0 +1,137 @@
package rootfstest
import (
"archive/tar"
"bytes"
"encoding/json"
"io"
"testing"
"github.com/stretchr/testify/require"
)
type (
Tarrer interface {
Tar(*tar.Writer)
}
Byter interface {
Bytes() []byte
}
Tarball []Tarrer
// Extractable is an empty interface for comparing extracted outputs in tests.
// Using that just to avoid the ugly `interface{}`.
Extractable interface{}
Dir struct {
Name string
Uid int
}
File struct {
Name string
Uid int
Contents Byter
}
Manifest []string
Hardlink struct {
Name string
Uid int
}
dockerManifestJSON []struct {
Layers []string `json:"Layers"`
}
)
func (tb Tarball) Bytes() []byte {
buf := bytes.Buffer{}
tw := tar.NewWriter(&buf)
for _, member := range tb {
member.Tar(tw)
}
tw.Close()
return buf.Bytes()
}
func (d Dir) Tar(tw *tar.Writer) {
hdr := &tar.Header{
Typeflag: tar.TypeDir,
Name: d.Name,
Mode: 0644,
Uid: d.Uid,
}
tw.WriteHeader(hdr)
}
func (f File) Tar(tw *tar.Writer) {
var contentbytes []byte
if f.Contents != nil {
contentbytes = f.Contents.Bytes()
}
hdr := &tar.Header{
Typeflag: tar.TypeReg,
Name: f.Name,
Mode: 0644,
Uid: f.Uid,
Size: int64(len(contentbytes)),
}
tw.WriteHeader(hdr)
tw.Write(contentbytes)
}
func (m Manifest) Tar(tw *tar.Writer) {
b, err := json.Marshal(dockerManifestJSON{{Layers: m}})
if err != nil {
panic("testerr")
}
File{
Name: "manifest.json",
Uid: 0,
Contents: bytes.NewBuffer(b),
}.Tar(tw)
}
func (h Hardlink) Tar(tw *tar.Writer) {
tw.WriteHeader(&tar.Header{
Typeflag: tar.TypeLink,
Name: h.Name,
Mode: 0644,
Uid: h.Uid,
})
}
func Extract(t *testing.T, r io.Reader) []Extractable {
t.Helper()
ret := []Extractable{}
tr := tar.NewReader(r)
for {
hdr, err := tr.Next()
if err == io.EOF {
break
}
require.NoError(t, err)
var elem Extractable
switch hdr.Typeflag {
case tar.TypeDir:
elem = Dir{Name: hdr.Name, Uid: hdr.Uid}
case tar.TypeLink:
elem = Hardlink{Name: hdr.Name}
case tar.TypeReg:
f := File{Name: hdr.Name, Uid: hdr.Uid}
if hdr.Size > 0 {
var buf bytes.Buffer
io.Copy(&buf, tr)
f.Contents = &buf
}
elem = f
}
ret = append(ret, elem)
}
return ret
}

28
rootfs/rootfstest/rootfstest_test.go Normal file
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@ -0,0 +1,28 @@
package rootfstest
import (
"bytes"
"testing"
"github.com/stretchr/testify/assert"
)
func TestTarball(t *testing.T) {
bk := Tarball{File{Name: "entrypoint.sh", Contents: bytes.NewBufferString("hello")}}
img := Tarball{
File{Name: "backup.tar", Contents: bk},
File{Name: "entrypoint.sh", Contents: bytes.NewBufferString("bye")},
Dir{Name: "bin"},
Hardlink{Name: "entrypoint2"},
}
got := Extract(t, bytes.NewBuffer(img.Bytes()))
want := []Extractable{
File{Name: "backup.tar", Contents: bytes.NewBuffer(bk.Bytes())},
File{Name: "entrypoint.sh", Contents: bytes.NewBufferString("bye")},
Dir{Name: "bin"},
Hardlink{Name: "entrypoint2"},
}
assert.Equal(t, want, got)
}