archive: Extract createTarFile() from ApplyLayer

This way we can reuse it for Untar()

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)

archive/archive.go

@@ -13,6 +13,7 @@ import (
 	"os/exec"
 	"path"
 	"path/filepath"
+	"syscall"
 )
 
 type Archive io.Reader
@@ -124,6 +125,84 @@ func (compression *Compression) Extension() string {
 	return ""
 }
 
+func createTarFile(path, extractDir string, hdr *tar.Header, reader *tar.Reader) error {
+	switch hdr.Typeflag {
+	case tar.TypeDir:
+		// Create directory unless it exists as a directory already.
+		// In that case we just want to merge the two
+		if fi, err := os.Lstat(path); !(err == nil && fi.IsDir()) {
+			if err := os.Mkdir(path, os.FileMode(hdr.Mode)); err != nil {
+				return err
+			}
+		}
+
+	case tar.TypeReg, tar.TypeRegA:
+		// Source is regular file
+		file, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY, os.FileMode(hdr.Mode))
+		if err != nil {
+			return err
+		}
+		if _, err := io.Copy(file, reader); err != nil {
+			file.Close()
+			return err
+		}
+		file.Close()
+
+	case tar.TypeBlock, tar.TypeChar, tar.TypeFifo:
+		mode := uint32(hdr.Mode & 07777)
+		switch hdr.Typeflag {
+		case tar.TypeBlock:
+			mode |= syscall.S_IFBLK
+		case tar.TypeChar:
+			mode |= syscall.S_IFCHR
+		case tar.TypeFifo:
+			mode |= syscall.S_IFIFO
+		}
+
+		if err := syscall.Mknod(path, mode, int(mkdev(hdr.Devmajor, hdr.Devminor))); err != nil {
+			return err
+		}
+
+	case tar.TypeLink:
+		if err := os.Link(filepath.Join(extractDir, hdr.Linkname), path); err != nil {
+			return err
+		}
+
+	case tar.TypeSymlink:
+		if err := os.Symlink(hdr.Linkname, path); err != nil {
+			return err
+		}
+
+	default:
+		return fmt.Errorf("Unhandled tar header type %d\n", hdr.Typeflag)
+	}
+
+	if err := syscall.Lchown(path, hdr.Uid, hdr.Gid); err != nil {
+		return err
+	}
+
+	// There is no LChmod, so ignore mode for symlink. Also, this
+	// must happen after chown, as that can modify the file mode
+	if hdr.Typeflag != tar.TypeSymlink {
+		if err := syscall.Chmod(path, uint32(hdr.Mode&07777)); err != nil {
+			return err
+		}
+	}
+
+	ts := []syscall.Timespec{timeToTimespec(hdr.AccessTime), timeToTimespec(hdr.ModTime)}
+	// syscall.UtimesNano doesn't support a NOFOLLOW flag atm, and
+	if hdr.Typeflag != tar.TypeSymlink {
+		if err := syscall.UtimesNano(path, ts); err != nil {
+			return err
+		}
+	} else {
+		if err := LUtimesNano(path, ts); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // Tar creates an archive from the directory at `path`, and returns it as a
 // stream of bytes.
 func Tar(path string, compression Compression) (io.Reader, error) {

archive/diff.go

@@ -2,7 +2,6 @@ package archive
 
 import (
 	"archive/tar"
-	"github.com/dotcloud/docker/utils"
 	"io"
 	"os"
 	"path/filepath"
@@ -89,95 +88,22 @@ func ApplyLayer(dest string, layer Archive) error {
 			// The only exception is when it is a directory *and* the file from
 			// the layer is also a directory. Then we want to merge them (i.e.
 			// just apply the metadata from the layer).
-			hasDir := false
 			if fi, err := os.Lstat(path); err == nil {
-				if fi.IsDir() && hdr.Typeflag == tar.TypeDir {
-					hasDir = true
-				} else {
+				if !(fi.IsDir() && hdr.Typeflag == tar.TypeDir) {
 					if err := os.RemoveAll(path); err != nil {
 						return err
 					}
 				}
 			}
 
-			switch hdr.Typeflag {
-			case tar.TypeDir:
-				if !hasDir {
-					err = os.Mkdir(path, os.FileMode(hdr.Mode))
-					if err != nil {
-						return err
-					}
-				}
-				dirs = append(dirs, hdr)
-
-			case tar.TypeReg, tar.TypeRegA:
-				// Source is regular file
-				file, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY, os.FileMode(hdr.Mode))
-				if err != nil {
-					return err
-				}
-				if _, err := io.Copy(file, tr); err != nil {
-					file.Close()
-					return err
-				}
-				file.Close()
-
-			case tar.TypeBlock, tar.TypeChar, tar.TypeFifo:
-				mode := uint32(hdr.Mode & 07777)
-				switch hdr.Typeflag {
-				case tar.TypeBlock:
-					mode |= syscall.S_IFBLK
-				case tar.TypeChar:
-					mode |= syscall.S_IFCHR
-				case tar.TypeFifo:
-					mode |= syscall.S_IFIFO
-				}
-
-				if err := syscall.Mknod(path, mode, int(mkdev(hdr.Devmajor, hdr.Devminor))); err != nil {
-					return err
-				}
-
-			case tar.TypeLink:
-				if err := os.Link(filepath.Join(dest, hdr.Linkname), path); err != nil {
-					return err
-				}
-
-			case tar.TypeSymlink:
-				if err := os.Symlink(hdr.Linkname, path); err != nil {
-					return err
-				}
-
-			default:
-				utils.Debugf("unhandled type %d\n", hdr.Typeflag)
-			}
-
-			if err = syscall.Lchown(path, hdr.Uid, hdr.Gid); err != nil {
+			if err := createTarFile(path, dest, hdr, tr); err != nil {
 				return err
 			}
 
-			// There is no LChmod, so ignore mode for symlink. Also, this
-			// must happen after chown, as that can modify the file mode
-			if hdr.Typeflag != tar.TypeSymlink {
-				err = syscall.Chmod(path, uint32(hdr.Mode&07777))
-				if err != nil {
-					return err
-				}
-			}
-
-			// Directories must be handled at the end to avoid further
-			// file creation in them to modify the mtime
-			if hdr.Typeflag != tar.TypeDir {
-				ts := []syscall.Timespec{timeToTimespec(hdr.AccessTime), timeToTimespec(hdr.ModTime)}
-				// syscall.UtimesNano doesn't support a NOFOLLOW flag atm, and
-				if hdr.Typeflag != tar.TypeSymlink {
-					if err := syscall.UtimesNano(path, ts); err != nil {
-						return err
-					}
-				} else {
-					if err := LUtimesNano(path, ts); err != nil {
-						return err
-					}
-				}
+			// Directory mtimes must be handled at the end to avoid further
+			// file creation in them to modify the directory mtime
+			if hdr.Typeflag == tar.TypeDir {
+				dirs = append(dirs, hdr)
 			}
 		}
 	}