| package archive |
| |
| import ( |
| "archive/tar" |
| "os" |
| "path/filepath" |
| "strings" |
| |
| "github.com/docker/docker/pkg/system" |
| "golang.org/x/sys/unix" |
| ) |
| |
| func getWhiteoutConverter(format WhiteoutFormat) tarWhiteoutConverter { |
| if format == OverlayWhiteoutFormat { |
| return overlayWhiteoutConverter{} |
| } |
| return nil |
| } |
| |
| type overlayWhiteoutConverter struct{} |
| |
| func (overlayWhiteoutConverter) ConvertWrite(hdr *tar.Header, path string, fi os.FileInfo) (wo *tar.Header, err error) { |
| // convert whiteouts to AUFS format |
| if fi.Mode()&os.ModeCharDevice != 0 && hdr.Devmajor == 0 && hdr.Devminor == 0 { |
| // we just rename the file and make it normal |
| dir, filename := filepath.Split(hdr.Name) |
| hdr.Name = filepath.Join(dir, WhiteoutPrefix+filename) |
| hdr.Mode = 0600 |
| hdr.Typeflag = tar.TypeReg |
| hdr.Size = 0 |
| } |
| |
| if fi.Mode()&os.ModeDir != 0 { |
| // convert opaque dirs to AUFS format by writing an empty file with the prefix |
| opaque, err := system.Lgetxattr(path, "trusted.overlay.opaque") |
| if err != nil { |
| return nil, err |
| } |
| if len(opaque) == 1 && opaque[0] == 'y' { |
| if hdr.Xattrs != nil { |
| delete(hdr.Xattrs, "trusted.overlay.opaque") |
| } |
| |
| // create a header for the whiteout file |
| // it should inherit some properties from the parent, but be a regular file |
| wo = &tar.Header{ |
| Typeflag: tar.TypeReg, |
| Mode: hdr.Mode & int64(os.ModePerm), |
| Name: filepath.Join(hdr.Name, WhiteoutOpaqueDir), |
| Size: 0, |
| Uid: hdr.Uid, |
| Uname: hdr.Uname, |
| Gid: hdr.Gid, |
| Gname: hdr.Gname, |
| AccessTime: hdr.AccessTime, |
| ChangeTime: hdr.ChangeTime, |
| } |
| } |
| } |
| |
| return |
| } |
| |
| func (overlayWhiteoutConverter) ConvertRead(hdr *tar.Header, path string) (bool, error) { |
| base := filepath.Base(path) |
| dir := filepath.Dir(path) |
| |
| // if a directory is marked as opaque by the AUFS special file, we need to translate that to overlay |
| if base == WhiteoutOpaqueDir { |
| err := unix.Setxattr(dir, "trusted.overlay.opaque", []byte{'y'}, 0) |
| // don't write the file itself |
| return false, err |
| } |
| |
| // if a file was deleted and we are using overlay, we need to create a character device |
| if strings.HasPrefix(base, WhiteoutPrefix) { |
| originalBase := base[len(WhiteoutPrefix):] |
| originalPath := filepath.Join(dir, originalBase) |
| |
| if err := unix.Mknod(originalPath, unix.S_IFCHR, 0); err != nil { |
| return false, err |
| } |
| if err := os.Chown(originalPath, hdr.Uid, hdr.Gid); err != nil { |
| return false, err |
| } |
| |
| // don't write the file itself |
| return false, nil |
| } |
| |
| return true, nil |
| } |