undocker

rootfs_test.go (5651B) - Raw

---

 package rootfs
 
 import (
 	"archive/tar"
 	"bytes"
 	"encoding/json"
 	"reflect"
 	"testing"
 
 	"git.jakstys.lt/motiejus/undocker/rootfs/internal/tartest"
 )
 
 type (
 	file        = tartest.File
 	dir         = tartest.Dir
 	hardlink    = tartest.Hardlink
 	extractable = tartest.Extractable
 	tarball     = tartest.Tarball
 )
 
 func TestRootFS(t *testing.T) {
 	layer0 := tarball{
 		dir{Name: "/", UID: 0},
 		file{Name: "/file", UID: 0, Contents: bytes.NewBufferString("from 0")},
 	}
 
 	layer1 := tarball{
 		file{Name: "/file", UID: 1, Contents: bytes.NewBufferString("from 1")},
 	}
 
 	layer2 := tarball{
 		dir{Name: "/", UID: 2},
 	}
 
 	tests := []struct {
 		name    string
 		image   tarball
 		want    []extractable
 		wantErr string
 	}{
 		{
 			name:  "empty tarball",
 			image: tarball{manifest{}},
 			want:  []extractable{},
 		},
 		{
 			name:    "no manifest",
 			image:   tarball{},
 			wantErr: "empty or missing manifest",
 		},
 		{
 			name:    "missing layer",
 			image:   tarball{manifest{"layer0/layer.tar"}},
 			wantErr: "layer0/layer.tar defined in manifest, missing in tarball",
 		},
 		{
 			name: "basic file overwrite, layer order mixed",
 			image: tarball{
 				file{Name: "layer1/layer.tar", Contents: layer1.Buffer()},
 				file{Name: "layer0/layer.tar", Contents: layer0.Buffer()},
 				manifest{"layer0/layer.tar", "layer1/layer.tar"},
 			},
 			want: []extractable{
 				dir{Name: "/", UID: 0},
 				file{Name: "/file", UID: 1, Contents: bytes.NewBufferString("from 1")},
 			},
 		},
 		{
 			name: "overwrite file with hardlink",
 			image: tarball{
 				file{Name: "layer0/layer.tar", Contents: tarball{
 					file{Name: "a"},
 				}.Buffer()},
 				file{Name: "layer1/layer.tar", Contents: tarball{
 					hardlink{Name: "a"},
 				}.Buffer()},
 				manifest{"layer0/layer.tar", "layer1/layer.tar"},
 			},
 			want: []extractable{
 				hardlink{Name: "a"},
 			},
 		},
 		{
 			name: "directory overwrite retains original dir",
 			image: tarball{
 				file{Name: "layer2/layer.tar", Contents: layer2.Buffer()},
 				file{Name: "layer0/layer.tar", Contents: layer0.Buffer()},
 				file{Name: "layer1/layer.tar", Contents: layer1.Buffer()},
 				manifest{"layer0/layer.tar", "layer1/layer.tar", "layer2/layer.tar"},
 			},
 			want: []extractable{
 				dir{Name: "/", UID: 0},
 				file{Name: "/file", UID: 1, Contents: bytes.NewBufferString("from 1")},
 				dir{Name: "/", UID: 2},
 			},
 		},
 		{
 			name: "simple whiteout",
 			image: tarball{
 				file{Name: "layer0/layer.tar", Contents: tarball{
 					file{Name: "filea"},
 					file{Name: "fileb"},
 					dir{Name: "dira"},
 					dir{Name: "dirb"},
 				}.Buffer()},
 				file{Name: "layer1/layer.tar", Contents: tarball{
 					hardlink{Name: ".wh.filea"},
 					hardlink{Name: ".wh.dira"},
 				}.Buffer()},
 				manifest{"layer0/layer.tar", "layer1/layer.tar"},
 			},
 			want: []extractable{
 				file{Name: "fileb"},
 				dir{Name: "dirb"},
 			},
 		},
 		{
 			name: "whiteout with override",
 			image: tarball{
 				file{Name: "layer0/layer.tar", Contents: tarball{
 					file{Name: "file", Contents: bytes.NewBufferString("from 0")},
 				}.Buffer()},
 				file{Name: "layer1/layer.tar", Contents: tarball{
 					hardlink{Name: ".wh.file"},
 				}.Buffer()},
 				file{Name: "layer2/layer.tar", Contents: tarball{
 					file{Name: "file", Contents: bytes.NewBufferString("from 3")},
 				}.Buffer()},
 				manifest{
 					"layer0/layer.tar",
 					"layer1/layer.tar",
 					"layer2/layer.tar",
 				},
 			},
 			want: []extractable{
 				file{Name: "file", Contents: bytes.NewBufferString("from 3")},
 			},
 		},
 		{
 			name: "directories do not whiteout",
 			image: tarball{
 				file{Name: "layer0/layer.tar", Contents: tarball{
 					dir{Name: "dir"},
 				}.Buffer()},
 				file{Name: "layer1/layer.tar", Contents: tarball{
 					dir{Name: ".wh.dir"},
 				}.Buffer()},
 				manifest{"layer0/layer.tar", "layer1/layer.tar"},
 			},
 			want: []extractable{
 				dir{Name: "dir"},
 				dir{Name: ".wh.dir"},
 			},
 		},
 		{
 			name: "simple readdir whiteout",
 			image: tarball{
 				file{Name: "layer0/layer.tar", Contents: tarball{
 					dir{Name: "a"},
 					file{Name: "a/filea"},
 				}.Buffer()},
 				file{Name: "layer1/layer.tar", Contents: tarball{
 					dir{Name: "a"},
 					file{Name: "a/fileb"},
 					hardlink{Name: "a/.wh..wh..opq"},
 				}.Buffer()},
 				manifest{"layer0/layer.tar", "layer1/layer.tar"},
 			},
 			want: []extractable{
 				dir{Name: "a"},
 				file{Name: "a/fileb"},
 			},
 		},
 		{
 			name: "archived layer",
 			image: tarball{
 				file{Name: "layer1/layer.tar", Contents: layer1.Gzip()},
 				file{Name: "layer0/layer.tar", Contents: layer0.Gzip()},
 				manifest{"layer0/layer.tar", "layer1/layer.tar"},
 			},
 			want: []extractable{
 				dir{Name: "/", UID: 0},
 				file{Name: "/file", UID: 1, Contents: bytes.NewBufferString("from 1")},
 			},
 		},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			in := bytes.NewReader(tt.image.Buffer().Bytes())
 			out := bytes.Buffer{}
 
 			err := Flatten(in, &out)
 			if tt.wantErr != "" {
 				if err == nil {
 					t.Fatal("expected error, got nil")
 				}
 				if tt.wantErr != err.Error() {
 					t.Errorf("want != got: %s != %s", tt.wantErr, err.Error())
 				}
 				return
 			}
 			outb := out.Bytes()
 			if err != nil {
 				t.Fatal("expected error, got nil")
 			}
 			got := tartest.Extract(t, bytes.NewReader(outb))
 			if !reflect.DeepEqual(tt.want, got) {
 				t.Errorf("want != got: %v != %v", tt.want, got)
 			}
 		})
 	}
 }
 
 // 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)
 }