Merge pull request #25 from justincormack/fix-symlinks-misc

Fix symlinks handling in initramfs

cmd/moby/build.go

@@ -136,28 +136,32 @@ func buildInternal(m *Moby, name string, pull bool) []byte {
 			log.Fatalf("Could not pull image %s: %v", m.Kernel.Image, err)
 		}
 	}
-	// get kernel and initrd tarball from container
+	if m.Kernel.Image != "" {
-	log.Infof("Extract kernel image: %s", m.Kernel.Image)
+		// get kernel and initrd tarball from container
-	const (
+		log.Infof("Extract kernel image: %s", m.Kernel.Image)
-		kernelName    = "kernel"
+		const (
-		kernelAltName = "bzImage"
+			kernelName    = "kernel"
-		ktarName      = "kernel.tar"
+			kernelAltName = "bzImage"
-	)
+			ktarName      = "kernel.tar"
-	out, err := ImageExtract(m.Kernel.Image, "", enforceContentTrust(m.Kernel.Image, &m.Trust), pull)
+		)
-	if err != nil {
+		out, err := ImageExtract(m.Kernel.Image, "", enforceContentTrust(m.Kernel.Image, &m.Trust), pull)
-		log.Fatalf("Failed to extract kernel image and tarball: %v", err)
+		if err != nil {
-	}
+			log.Fatalf("Failed to extract kernel image and tarball: %v", err)
-	buf := bytes.NewBuffer(out)
+		}
+		buf := bytes.NewBuffer(out)
 
-	kernel, ktar, err := untarKernel(buf, kernelName, kernelAltName, ktarName, m.Kernel.Cmdline)
+		kernel, ktar, err := untarKernel(buf, kernelName, kernelAltName, ktarName, m.Kernel.Cmdline)
-	if err != nil {
+		if err != nil {
-		log.Fatalf("Could not extract kernel image and filesystem from tarball. %v", err)
+			log.Fatalf("Could not extract kernel image and filesystem from tarball. %v", err)
+		}
+		initrdAppend(iw, kernel)
+		initrdAppend(iw, ktar)
 	}
-	initrdAppend(iw, kernel)
-	initrdAppend(iw, ktar)
 
 	// convert init images to tarballs
-	log.Infof("Add init containers:")
+	if len(m.Init) != 0 {
+		log.Infof("Add init containers:")
+	}
 	for _, ii := range m.Init {
 		log.Infof("Process init image: %s", ii)
 		init, err := ImageExtract(ii, "", enforceContentTrust(ii, &m.Trust), pull)
@@ -168,7 +172,9 @@ func buildInternal(m *Moby, name string, pull bool) []byte {
 		initrdAppend(iw, buffer)
 	}
 
-	log.Infof("Add onboot containers:")
+	if len(m.Onboot) != 0 {
+		log.Infof("Add onboot containers:")
+	}
 	for i, image := range m.Onboot {
 		log.Infof("  Create OCI config for %s", image.Image)
 		config, err := ConfigToOCI(&image)
@@ -185,7 +191,9 @@ func buildInternal(m *Moby, name string, pull bool) []byte {
 		initrdAppend(iw, buffer)
 	}
 
-	log.Infof("Add service containers:")
+	if len(m.Services) != 0 {
+		log.Infof("Add service containers:")
+	}
 	for _, image := range m.Services {
 		log.Infof("  Create OCI config for %s", image.Image)
 		config, err := ConfigToOCI(&image)

cmd/moby/config.go

@@ -32,6 +32,7 @@ type Moby struct {
 	Files    []struct {
 		Path      string
 		Directory bool
+		Symlink   string
 		Contents  string
 	}
 	Outputs []struct {
@@ -430,13 +431,15 @@ func filesystem(m *Moby) (*bytes.Buffer, error) {
 	tw := tar.NewWriter(buf)
 	defer tw.Close()
 
-	log.Infof("Add files:")
+	if len(m.Files) != 0 {
+		log.Infof("Add files:")
+	}
 	for _, f := range m.Files {
 		log.Infof("  %s", f.Path)
 		if f.Path == "" {
 			return buf, errors.New("Did not specify path for file")
 		}
-		if !f.Directory && f.Contents == "" {
+		if !f.Directory && f.Contents == "" && f.Symlink == "" {
 			return buf, errors.New("Contents of file not specified")
 		}
 		// we need all the leading directories
@@ -475,6 +478,17 @@ func filesystem(m *Moby) (*bytes.Buffer, error) {
 			if err != nil {
 				return buf, err
 			}
+		} else if f.Symlink != "" {
+			hdr := &tar.Header{
+				Name:     f.Path,
+				Typeflag: tar.TypeSymlink,
+				Mode:     0600,
+				Linkname: f.Symlink,
+			}
+			err := tw.WriteHeader(hdr)
+			if err != nil {
+				return buf, err
+			}
 		} else {
 			hdr := &tar.Header{
 				Name: f.Path,

cmd/moby/output.go

@@ -111,6 +111,7 @@ func tarToInitrd(image []byte) ([]byte, []byte, string, error) {
 	if err != nil {
 		return []byte{}, []byte{}, "", err
 	}
+	iw.Close()
 	return kernel, w.Bytes(), cmdline, nil
 }
 

cmd/moby/schema.go

@@ -20,6 +20,7 @@ var schema = string(`
         "properties": {
           "path": {"type": "string"},
           "directory": {"type": "boolean"},
+          "symlink": {"type": "string"},
           "contents": {"type": "string"}
         }
     },

vendor.conf

@@ -4,7 +4,7 @@ github.com/docker/docker 420b67f892d5424be59a788a51e2c4e64bb9cd66
 github.com/docker/go-connections e15c02316c12de00874640cd76311849de2aeed5
 github.com/docker/go-units 651fc226e7441360384da338d0fd37f2440ffbe3
 github.com/docker/libtrust 9cbd2a1374f46905c68a4eb3694a130610adc62a
-github.com/linuxkit/linuxkit 17dd50cec61de35c48b786998a154678dc46ff6a
+github.com/linuxkit/linuxkit ad8a4cad1f45a08f7dbc0ab02f28be31f767f1fd
 github.com/opencontainers/go-digest a6d0ee40d4207ea02364bd3b9e8e77b9159ba1eb
 github.com/opencontainers/runtime-spec d094a5c9c1997ab086197b57e9378fabed394d92
 github.com/pkg/errors ff09b135c25aae272398c51a07235b90a75aa4f0

vendor/github.com/linuxkit/linuxkit/src/initrd/initrd.go

@@ -45,6 +45,43 @@ func typeconv(thdr *tar.Header) int64 {
 	}
 }
 
+func copyTarEntry(w *Writer, thdr *tar.Header, r *tar.Reader) (written int64, err error) {
+	tp := typeconv(thdr)
+	if tp == -1 {
+		return written, errors.New("cannot convert tar file")
+	}
+	size := thdr.Size
+	if tp == cpio.TYPE_SYMLINK {
+		size = int64(len(thdr.Linkname))
+	}
+	chdr := cpio.Header{
+		Mode:     thdr.Mode,
+		Uid:      thdr.Uid,
+		Gid:      thdr.Gid,
+		Mtime:    thdr.ModTime.Unix(),
+		Size:     size,
+		Devmajor: thdr.Devmajor,
+		Devminor: thdr.Devminor,
+		Type:     tp,
+		Name:     thdr.Name,
+	}
+	err = w.WriteHeader(&chdr)
+	if err != nil {
+		return
+	}
+	var n int64
+	switch tp {
+	case cpio.TYPE_SYMLINK:
+		buffer := bytes.NewBufferString(thdr.Linkname)
+		n, err = io.Copy(w, buffer)
+	case cpio.TYPE_REG:
+		n, err = io.Copy(w, r)
+	}
+	written += n
+
+	return
+}
+
 // CopyTar copies a tar stream into an initrd
 func CopyTar(w *Writer, r *tar.Reader) (written int64, err error) {
 	for {
@@ -56,37 +93,7 @@ func CopyTar(w *Writer, r *tar.Reader) (written int64, err error) {
 		if err != nil {
 			return
 		}
-		tp := typeconv(thdr)
+		written, err = copyTarEntry(w, thdr, r)
-		if tp == -1 {
-			return written, errors.New("cannot convert tar file")
-		}
-		size := thdr.Size
-		if tp == cpio.TYPE_SYMLINK {
-			size = int64(len(thdr.Linkname))
-		}
-		chdr := cpio.Header{
-			Mode:     thdr.Mode,
-			Uid:      thdr.Uid,
-			Gid:      thdr.Gid,
-			Mtime:    thdr.ModTime.Unix(),
-			Size:     size,
-			Devmajor: thdr.Devmajor,
-			Devminor: thdr.Devminor,
-			Type:     tp,
-			Name:     thdr.Name,
-		}
-		err = w.WriteHeader(&chdr)
-		if err != nil {
-			return
-		}
-		var n int64
-		if tp == cpio.TYPE_SYMLINK {
-			buffer := bytes.NewBufferString(thdr.Linkname)
-			n, err = io.Copy(w, buffer)
-		} else {
-			n, err = io.Copy(w, r)
-		}
-		written += n
 		if err != nil {
 			return
 		}
@@ -104,10 +111,6 @@ func CopySplitTar(w *Writer, r *tar.Reader) (kernel []byte, cmdline string, err
 		if err != nil {
 			return
 		}
-		tp := typeconv(thdr)
-		if tp == -1 {
-			return kernel, cmdline, errors.New("cannot convert tar file")
-		}
 		switch thdr.Name {
 		case "boot/kernel":
 			kernel, err = ioutil.ReadAll(r)
@@ -122,32 +125,9 @@ func CopySplitTar(w *Writer, r *tar.Reader) (kernel []byte, cmdline string, err
 			}
 			cmdline = string(buf)
 		case "boot":
+			// skip this entry
 		default:
-			size := thdr.Size
+			_, err = copyTarEntry(w, thdr, r)
-			if tp == cpio.TYPE_SYMLINK {
-				size = int64(len(thdr.Linkname))
-			}
-			chdr := cpio.Header{
-				Mode:     thdr.Mode,
-				Uid:      thdr.Uid,
-				Gid:      thdr.Gid,
-				Mtime:    thdr.ModTime.Unix(),
-				Size:     size,
-				Devmajor: thdr.Devmajor,
-				Devminor: thdr.Devminor,
-				Type:     tp,
-				Name:     thdr.Name,
-			}
-			err = w.WriteHeader(&chdr)
-			if err != nil {
-				return
-			}
-			if tp == cpio.TYPE_SYMLINK {
-				buffer := bytes.NewBufferString(thdr.Linkname)
-				_, err = io.Copy(w, buffer)
-			} else {
-				_, err = io.Copy(w, r)
-			}
 			if err != nil {
 				return
 			}