Golang system.Lsetxattr函数代码示例

// hasOpaqueCopyUpBug checks whether the filesystem has a bug
// which copies up the opaque flag when copying up an opaque
// directory. When this bug exists naive diff should be used.
func hasOpaqueCopyUpBug(d string) error {
	td, err := ioutil.TempDir(d, "opaque-bug-check")
	if err != nil {
		return err
	}
	defer func() {
		if err := os.RemoveAll(td); err != nil {
			logrus.Warnf("Failed to remove check directory %v: %v", td, err)
		}
	}()

	// Make directories l1/d, l2/d, l3, work, merged
	if err := os.MkdirAll(filepath.Join(td, "l1", "d"), 0755); err != nil {
		return err
	}
	if err := os.MkdirAll(filepath.Join(td, "l2", "d"), 0755); err != nil {
		return err
	}
	if err := os.Mkdir(filepath.Join(td, "l3"), 0755); err != nil {
		return err
	}
	if err := os.Mkdir(filepath.Join(td, "work"), 0755); err != nil {
		return err
	}
	if err := os.Mkdir(filepath.Join(td, "merged"), 0755); err != nil {
		return err
	}

	// Mark l2/d as opaque
	if err := system.Lsetxattr(filepath.Join(td, "l2", "d"), "trusted.overlay.opaque", []byte("y"), 0); err != nil {
		return errors.Wrap(err, "failed to set opaque flag on middle layer")
	}

	opts := fmt.Sprintf("lowerdir=%s:%s,upperdir=%s,workdir=%s", path.Join(td, "l2"), path.Join(td, "l1"), path.Join(td, "l3"), path.Join(td, "work"))
	if err := syscall.Mount("overlay", filepath.Join(td, "merged"), "overlay", 0, opts); err != nil {
		return errors.Wrap(err, "failed to mount overlay")
	}
	defer func() {
		if err := syscall.Unmount(filepath.Join(td, "merged"), 0); err != nil {
			logrus.Warnf("Failed to unmount check directory %v: %v", filepath.Join(td, "merged"), err)
		}
	}()

	// Touch file in d to force copy up of opaque directory "d" from "l2" to "l3"
	if err := ioutil.WriteFile(filepath.Join(td, "merged", "d", "f"), []byte{}, 0644); err != nil {
		return errors.Wrap(err, "failed to write to merged directory")
	}

	// Check l3/d does not have opaque flag
	xattrOpaque, err := system.Lgetxattr(filepath.Join(td, "l3", "d"), "trusted.overlay.opaque")
	if err != nil {
		return errors.Wrap(err, "failed to read opaque flag on upper layer")
	}
	if string(xattrOpaque) == "y" {
		return errors.New("opaque flag erroneously copied up, consider update to kernel 4.8 or later to fix")
	}

	return nil
}

func copyXattr(srcPath, dstPath, attr string) error {
	data, err := system.Lgetxattr(srcPath, attr)
	if err != nil {
		return err
	}
	if data != nil {
		if err := system.Lsetxattr(dstPath, attr, data, 0); err != nil {
			return err
		}
	}
	return nil
}

// setupOverlayTestDir creates files in a directory with overlay whiteouts
// Tree layout
// .
// ├── d1     # opaque, 0700
// │   └── f1 # empty file, 0600
// ├── d2     # opaque, 0750
// │   └── f1 # empty file, 0660
// └── d3     # 0700
//     └── f1 # whiteout, 0644
func setupOverlayTestDir(t *testing.T, src string) {
	// Create opaque directory containing single file and permission 0700
	if err := os.Mkdir(filepath.Join(src, "d1"), 0700); err != nil {
		t.Fatal(err)
	}

	if err := system.Lsetxattr(filepath.Join(src, "d1"), "trusted.overlay.opaque", []byte("y"), 0); err != nil {
		t.Fatal(err)
	}

	if err := ioutil.WriteFile(filepath.Join(src, "d1", "f1"), []byte{}, 0600); err != nil {
		t.Fatal(err)
	}

	// Create another opaque directory containing single file but with permission 0750
	if err := os.Mkdir(filepath.Join(src, "d2"), 0750); err != nil {
		t.Fatal(err)
	}

	if err := system.Lsetxattr(filepath.Join(src, "d2"), "trusted.overlay.opaque", []byte("y"), 0); err != nil {
		t.Fatal(err)
	}

	if err := ioutil.WriteFile(filepath.Join(src, "d2", "f1"), []byte{}, 0660); err != nil {
		t.Fatal(err)
	}

	// Create regular directory with deleted file
	if err := os.Mkdir(filepath.Join(src, "d3"), 0700); err != nil {
		t.Fatal(err)
	}

	if err := system.Mknod(filepath.Join(src, "d3", "f1"), syscall.S_IFCHR, 0); err != nil {
		t.Fatal(err)
	}
}

// TestTarUntarWithXattr is Unix as Lsetxattr is not supported on Windows
func TestTarUntarWithXattr(t *testing.T) {
	if runtime.GOOS == "solaris" {
		t.Skip()
	}
	origin, err := ioutil.TempDir("", "docker-test-untar-origin")
	if err != nil {
		t.Fatal(err)
	}
	defer os.RemoveAll(origin)
	if err := ioutil.WriteFile(filepath.Join(origin, "1"), []byte("hello world"), 0700); err != nil {
		t.Fatal(err)
	}
	if err := ioutil.WriteFile(filepath.Join(origin, "2"), []byte("welcome!"), 0700); err != nil {
		t.Fatal(err)
	}
	if err := ioutil.WriteFile(filepath.Join(origin, "3"), []byte("will be ignored"), 0700); err != nil {
		t.Fatal(err)
	}
	if err := system.Lsetxattr(filepath.Join(origin, "2"), "security.capability", []byte{0x00}, 0); err != nil {
		t.Fatal(err)
	}

	for _, c := range []Compression{
		Uncompressed,
		Gzip,
	} {
		changes, err := tarUntar(t, origin, &TarOptions{
			Compression:     c,
			ExcludePatterns: []string{"3"},
		})

		if err != nil {
			t.Fatalf("Error tar/untar for compression %s: %s", c.Extension(), err)
		}

		if len(changes) != 1 || changes[0].Path != "/3" {
			t.Fatalf("Unexpected differences after tarUntar: %v", changes)
		}
		capability, _ := system.Lgetxattr(filepath.Join(origin, "2"), "security.capability")
		if capability == nil && capability[0] != 0x00 {
			t.Fatalf("Untar should have kept the 'security.capability' xattr.")
		}
	}
}

func createTarFile(path, extractDir string, hdr *tar.Header, reader io.Reader, Lchown bool) error {
	// hdr.Mode is in linux format, which we can use for sycalls,
	// but for os.Foo() calls we need the mode converted to os.FileMode,
	// so use hdrInfo.Mode() (they differ for e.g. setuid bits)
	hdrInfo := hdr.FileInfo()

	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, hdrInfo.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, hdrInfo.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:
		targetPath := filepath.Join(extractDir, hdr.Linkname)
		// check for hardlink breakout
		if !strings.HasPrefix(targetPath, extractDir) {
			return breakoutError(fmt.Errorf("invalid hardlink %q -> %q", targetPath, hdr.Linkname))
		}
		if err := os.Link(targetPath, path); err != nil {
			return err
		}

	case tar.TypeSymlink:
		// 	path 				-> hdr.Linkname = targetPath
		// e.g. /extractDir/path/to/symlink 	-> ../2/file	= /extractDir/path/2/file
		targetPath := filepath.Join(filepath.Dir(path), hdr.Linkname)

		// the reason we don't need to check symlinks in the path (with FollowSymlinkInScope) is because
		// that symlink would first have to be created, which would be caught earlier, at this very check:
		if !strings.HasPrefix(targetPath, extractDir) {
			return breakoutError(fmt.Errorf("invalid symlink %q -> %q", path, hdr.Linkname))
		}
		if err := os.Symlink(hdr.Linkname, path); err != nil {
			return err
		}

	case tar.TypeXGlobalHeader:
		log.Debugf("PAX Global Extended Headers found and ignored")
		return nil

	default:
		return fmt.Errorf("Unhandled tar header type %d\n", hdr.Typeflag)
	}

	if err := os.Lchown(path, hdr.Uid, hdr.Gid); err != nil && Lchown {
		return err
	}

	for key, value := range hdr.Xattrs {
		if err := system.Lsetxattr(path, key, []byte(value), 0); 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 := os.Chmod(path, hdrInfo.Mode()); 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 := system.UtimesNano(path, ts); err != nil && err != system.ErrNotSupportedPlatform {
			return err
		}
	} else {
//.........这里部分代码省略.........

func createTarFile(path, extractDir string, hdr *tar.Header, reader io.Reader, Lchown bool, chownOpts *TarChownOptions, inUserns bool) error {
	// hdr.Mode is in linux format, which we can use for sycalls,
	// but for os.Foo() calls we need the mode converted to os.FileMode,
	// so use hdrInfo.Mode() (they differ for e.g. setuid bits)
	hdrInfo := hdr.FileInfo()

	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, hdrInfo.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, hdrInfo.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:
		if inUserns { // cannot create devices in a userns
			return nil
		}
		// Handle this is an OS-specific way
		if err := handleTarTypeBlockCharFifo(hdr, path); err != nil {
			return err
		}

	case tar.TypeFifo:
		// Handle this is an OS-specific way
		if err := handleTarTypeBlockCharFifo(hdr, path); err != nil {
			return err
		}

	case tar.TypeLink:
		targetPath := filepath.Join(extractDir, hdr.Linkname)
		// check for hardlink breakout
		if !strings.HasPrefix(targetPath, extractDir) {
			return breakoutError(fmt.Errorf("invalid hardlink %q -> %q", targetPath, hdr.Linkname))
		}
		if err := os.Link(targetPath, path); err != nil {
			return err
		}

	case tar.TypeSymlink:
		// 	path 				-> hdr.Linkname = targetPath
		// e.g. /extractDir/path/to/symlink 	-> ../2/file	= /extractDir/path/2/file
		targetPath := filepath.Join(filepath.Dir(path), hdr.Linkname)

		// the reason we don't need to check symlinks in the path (with FollowSymlinkInScope) is because
		// that symlink would first have to be created, which would be caught earlier, at this very check:
		if !strings.HasPrefix(targetPath, extractDir) {
			return breakoutError(fmt.Errorf("invalid symlink %q -> %q", path, hdr.Linkname))
		}
		if err := os.Symlink(hdr.Linkname, path); err != nil {
			return err
		}

	case tar.TypeXGlobalHeader:
		logrus.Debug("PAX Global Extended Headers found and ignored")
		return nil

	default:
		return fmt.Errorf("Unhandled tar header type %d\n", hdr.Typeflag)
	}

	// Lchown is not supported on Windows.
	if Lchown && runtime.GOOS != "windows" {
		if chownOpts == nil {
			chownOpts = &TarChownOptions{UID: hdr.Uid, GID: hdr.Gid}
		}
		if err := os.Lchown(path, chownOpts.UID, chownOpts.GID); err != nil {
			return err
		}
	}

	var errors []string
	for key, value := range hdr.Xattrs {
		if err := system.Lsetxattr(path, key, []byte(value), 0); err != nil {
			if err == syscall.ENOTSUP {
				// We ignore errors here because not all graphdrivers support
				// xattrs *cough* old versions of AUFS *cough*. However only
				// ENOTSUP should be emitted in that case, otherwise we still
				// bail.
				errors = append(errors, err.Error())
				continue
			}
			return err
		}

	}
//.........这里部分代码省略.........