undocker/rootfs/internal/tartest/tartest.go

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package tartest
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import (
"archive/tar"
"bytes"
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"compress/gzip"
"fmt"
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"io"
"testing"
)
type (
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// Tarrer is an object that can tar itself to an archive
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Tarrer interface {
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Tar(*tar.Writer) error
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}
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// Tarball is a list of tarrables
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Tarball []Tarrer
// Extractable is an empty interface for comparing extracted outputs in tests.
// Using that just to avoid the ugly `interface{}`.
Extractable interface{}
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// Dir is a tarrable directory representation
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Dir struct {
Name string
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UID int
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}
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// File is a tarrable file representation
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File struct {
Name string
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UID int
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Contents *bytes.Buffer
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}
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// Hardlink is a representation of a hardlink
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Hardlink struct {
Name string
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UID int
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}
)
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// Buffer returns a byte buffer
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func (tb Tarball) Buffer() *bytes.Buffer {
var buf bytes.Buffer
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tw := tar.NewWriter(&buf)
for _, member := range tb {
member.Tar(tw)
}
tw.Close()
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return &buf
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}
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// Gzip returns a gzipped buffer
func (tb Tarball) Gzip() *bytes.Buffer {
var buf bytes.Buffer
w := gzip.NewWriter(&buf)
_, err := io.Copy(w, tb.Buffer())
if err != nil {
panic(fmt.Errorf("Gzip(): %w", err))
}
if err := w.Close(); err != nil {
panic(fmt.Errorf("gzip.Close(): %w", err))
}
return &buf
}
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// Tar tars the Dir
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func (d Dir) Tar(tw *tar.Writer) error {
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hdr := &tar.Header{
Typeflag: tar.TypeDir,
Name: d.Name,
Mode: 0644,
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Uid: d.UID,
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}
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return tw.WriteHeader(hdr)
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}
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// Tar tars the File
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func (f File) Tar(tw *tar.Writer) error {
var contents []byte
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if f.Contents != nil {
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contents = f.Contents.Bytes()
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}
hdr := &tar.Header{
Typeflag: tar.TypeReg,
Name: f.Name,
Mode: 0644,
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Uid: f.UID,
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Size: int64(len(contents)),
}
if err := tw.WriteHeader(hdr); err != nil {
return err
}
if _, err := tw.Write(contents); err != nil {
return err
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}
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return nil
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}
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// Tar tars the Hardlink
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func (h Hardlink) Tar(tw *tar.Writer) error {
return tw.WriteHeader(&tar.Header{
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Typeflag: tar.TypeLink,
Name: h.Name,
Mode: 0644,
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Uid: h.UID,
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})
}
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// Extract extracts a tarball to a slice of extractables
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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
}
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if err != nil {
t.Errorf("expected nil error: %v", err)
}
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var elem Extractable
switch hdr.Typeflag {
case tar.TypeDir:
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elem = Dir{Name: hdr.Name, UID: hdr.Uid}
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case tar.TypeLink:
elem = Hardlink{Name: hdr.Name}
case tar.TypeReg:
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f := File{Name: hdr.Name, UID: hdr.Uid}
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if hdr.Size > 0 {
var buf bytes.Buffer
io.Copy(&buf, tr)
f.Contents = &buf
}
elem = f
}
ret = append(ret, elem)
}
return ret
}