native Recv WIP

cmd/gbtrfs.go

@@ -96,7 +96,7 @@ var SendCmd = &cobra.Command{
 }
 
 var ReceiveCmd = &cobra.Command{
-	Use:   "receive [-ve] [-f <infile>] [--max-errors <N>] <mount>",
+	Use:   "receive [-v] [-f <infile>] [--max-errors <N>] <mount>",
 	Short: "Receive subvolumes from stdin.",
 	Long: `Receives one or more subvolumes that were previously
 sent with btrfs send. The received subvolumes are stored

receive.go

@@ -2,31 +2,135 @@ package btrfs
 
 import (
 	"bytes"
+	"encoding/binary"
 	"errors"
+	"fmt"
+	"hash/crc32"
 	"io"
+	"os"
 	"os/exec"
+	"path/filepath"
+	"syscall"
 )
 
-func Receive(r io.Reader, mount string) error {
-	// TODO: write a native implementation?
-	//tf, err := ioutil.TempFile("","btrfs_snap")
-	//if err != nil {
-	//	return err
-	//}
-	//defer func(){
-	//	name := tf.Name()
-	//	tf.Close()
-	//	os.Remove(name)
-	//}()
-	buf := bytes.NewBuffer(nil)
-	cmd := exec.Command("btrfs", "receive", mount)
-	cmd.Stdin = r
-	cmd.Stderr = buf
-	if err := cmd.Run(); err != nil {
-		if buf.Len() != 0 {
-			return errors.New(buf.String())
+const nativeReceive = false
+
+func Receive(r io.Reader, dstDir string) error {
+	if !nativeReceive {
+		buf := bytes.NewBuffer(nil)
+		cmd := exec.Command("btrfs", "receive", dstDir)
+		cmd.Stdin = r
+		cmd.Stderr = buf
+		if err := cmd.Run(); err != nil {
+			if buf.Len() != 0 {
+				return errors.New(buf.String())
+			}
+			return err
 		}
+		return nil
+	}
+	var err error
+	dstDir, err = filepath.Abs(dstDir)
+	if err != nil {
 		return err
 	}
-	return nil
+	realMnt, err := findMountRoot(dstDir)
+	if err != nil {
+		return err
+	}
+	dir, err := os.OpenFile(dstDir, os.O_RDONLY|syscall.O_NOATIME, 0755)
+	if err != nil {
+		return err
+	}
+	mnt, err := os.OpenFile(realMnt, os.O_RDONLY|syscall.O_NOATIME, 0755)
+	if err != nil {
+		return err
+	}
+	// We want to resolve the path to the subvolume we're sitting in
+	// so that we can adjust the paths of any subvols we want to receive in.
+	subvolID, err := getPathRootID(mnt)
+	if err != nil {
+		return err
+	}
+	sr, err := newStreamReader(r)
+	if err != nil {
+		return err
+	}
+	_, _, _ = dir, subvolID, sr
+	panic("not implemented")
+}
+
+type streamReader struct {
+	r    io.Reader
+	hbuf []byte
+	buf  *bytes.Buffer
+}
+type sendCommandArgs struct {
+	Type tlvType
+	Data []byte
+}
+type sendCommand struct {
+	Type sendCmd
+	Args []sendCommandArgs
+}
+
+func (sr *streamReader) ReadCommand() (*sendCommand, error) {
+	sr.buf.Reset()
+	var h cmdHeader
+	if sr.hbuf == nil {
+		sr.hbuf = make([]byte, h.Size())
+	}
+	if _, err := io.ReadFull(sr.r, sr.hbuf); err != nil {
+		return nil, err
+	} else if err = h.Unmarshal(sr.hbuf); err != nil {
+		return nil, err
+	}
+	if sr.buf == nil {
+		sr.buf = bytes.NewBuffer(nil)
+	}
+	if _, err := io.CopyN(sr.buf, sr.r, int64(h.Len)); err != nil {
+		return nil, err
+	}
+	tbl := crc32.MakeTable(0)
+	crc := crc32.Checksum(sr.buf.Bytes(), tbl)
+	if crc != h.Crc {
+		return nil, fmt.Errorf("crc missmatch in command: %x vs %x", crc, h.Crc)
+	}
+	cmd := sendCommand{Type: sendCmd(h.Cmd)}
+	var th tlvHeader
+	data := sr.buf.Bytes()
+	for {
+		if n := len(data); n < th.Size() {
+			if n != 0 {
+				return nil, io.ErrUnexpectedEOF
+			}
+			break
+		}
+		if err := th.Unmarshal(data); err != nil {
+			return nil, err
+		}
+		data = data[th.Size():]
+		if th.Type > _BTRFS_SEND_A_MAX { // || th.Len > _BTRFS_SEND_BUF_SIZE {
+			return nil, fmt.Errorf("invalid tlv in cmd: %+v", th)
+		}
+		b := make([]byte, th.Len)
+		copy(b, data)
+		cmd.Args = append(cmd.Args, sendCommandArgs{Type: th.Type, Data: b})
+	}
+	return &cmd, nil
+}
+
+func newStreamReader(r io.Reader) (*streamReader, error) {
+	buf := make([]byte, sendStreamMagicSize+4)
+	_, err := io.ReadFull(r, buf)
+	if err != nil {
+		return nil, err
+	} else if bytes.Compare(buf[:sendStreamMagicSize], []byte(_BTRFS_SEND_STREAM_MAGIC)) != 0 {
+		return nil, errors.New("unexpected stream header")
+	}
+	version := binary.LittleEndian.Uint32(buf[sendStreamMagicSize:])
+	if version > _BTRFS_SEND_STREAM_VERSION {
+		return nil, fmt.Errorf("stream version %d not supported", version)
+	}
+	return &streamReader{r: r}, nil
 }

send_h.go

@@ -0,0 +1,144 @@
+package btrfs
+
+import (
+	"encoding/binary"
+	"io"
+)
+
+const (
+	_BTRFS_SEND_STREAM_MAGIC   = "btrfs-stream"
+	sendStreamMagicSize        = len(_BTRFS_SEND_STREAM_MAGIC)
+	_BTRFS_SEND_STREAM_VERSION = 1
+)
+
+const (
+	_BTRFS_SEND_BUF_SIZE  = 64 * 1024
+	_BTRFS_SEND_READ_SIZE = 48 * 1024
+)
+
+type tlvType uint16
+
+const (
+	tlvU8 = tlvType(iota)
+	tlvU16
+	tlvU32
+	tlvU64
+	tlvBinary
+	tlvString
+	tlvUUID
+	tlvTimespec
+)
+
+type streamHeader struct {
+	Magic   [len(_BTRFS_SEND_STREAM_MAGIC)]byte
+	Version uint32
+}
+
+type cmdHeader struct {
+	Len uint32 // len excluding the header
+	Cmd uint16
+	Crc uint32 // crc including the header with zero crc field
+}
+
+func (h *cmdHeader) Size() int { return 10 }
+func (h *cmdHeader) Unmarshal(p []byte) error {
+	if len(p) < h.Size() {
+		return io.ErrUnexpectedEOF
+	}
+	h.Len = binary.LittleEndian.Uint32(p[0:])
+	h.Cmd = binary.LittleEndian.Uint16(p[4:])
+	h.Crc = binary.LittleEndian.Uint32(p[6:])
+	return nil
+}
+
+type tlvHeader struct {
+	Type tlvType
+	Len  uint16 // len excluding the header
+}
+
+func (h *tlvHeader) Size() int { return 4 }
+func (h *tlvHeader) Unmarshal(p []byte) error {
+	if len(p) < h.Size() {
+		return io.ErrUnexpectedEOF
+	}
+	h.Type = tlvType(binary.LittleEndian.Uint16(p[0:]))
+	h.Len = binary.LittleEndian.Uint16(p[2:])
+	return nil
+}
+
+type sendCmd uint16
+
+const (
+	_BTRFS_SEND_C_UNSPEC = sendCmd(iota)
+
+	_BTRFS_SEND_C_SUBVOL
+	_BTRFS_SEND_C_SNAPSHOT
+
+	_BTRFS_SEND_C_MKFILE
+	_BTRFS_SEND_C_MKDIR
+	_BTRFS_SEND_C_MKNOD
+	_BTRFS_SEND_C_MKFIFO
+	_BTRFS_SEND_C_MKSOCK
+	_BTRFS_SEND_C_SYMLINK
+
+	_BTRFS_SEND_C_RENAME
+	_BTRFS_SEND_C_LINK
+	_BTRFS_SEND_C_UNLINK
+	_BTRFS_SEND_C_RMDIR
+
+	_BTRFS_SEND_C_SET_XATTR
+	_BTRFS_SEND_C_REMOVE_XATTR
+
+	_BTRFS_SEND_C_WRITE
+	_BTRFS_SEND_C_CLONE
+
+	_BTRFS_SEND_C_TRUNCATE
+	_BTRFS_SEND_C_CHMOD
+	_BTRFS_SEND_C_CHOWN
+	_BTRFS_SEND_C_UTIMES
+
+	_BTRFS_SEND_C_END
+	_BTRFS_SEND_C_UPDATE_EXTENT
+	__BTRFS_SEND_C_MAX
+)
+
+const _BTRFS_SEND_C_MAX = __BTRFS_SEND_C_MAX - 1
+
+type sendCmdAttr uint16
+
+const (
+	_BTRFS_SEND_A_UNSPEC = iota
+
+	_BTRFS_SEND_A_UUID
+	_BTRFS_SEND_A_CTRANSID
+
+	_BTRFS_SEND_A_INO
+	_BTRFS_SEND_A_SIZE
+	_BTRFS_SEND_A_MODE
+	_BTRFS_SEND_A_UID
+	_BTRFS_SEND_A_GID
+	_BTRFS_SEND_A_RDEV
+	_BTRFS_SEND_A_CTIME
+	_BTRFS_SEND_A_MTIME
+	_BTRFS_SEND_A_ATIME
+	_BTRFS_SEND_A_OTIME
+
+	_BTRFS_SEND_A_XATTR_NAME
+	_BTRFS_SEND_A_XATTR_DATA
+
+	_BTRFS_SEND_A_PATH
+	_BTRFS_SEND_A_PATH_TO
+	_BTRFS_SEND_A_PATH_LINK
+
+	_BTRFS_SEND_A_FILE_OFFSET
+	_BTRFS_SEND_A_DATA
+
+	_BTRFS_SEND_A_CLONE_UUID
+	_BTRFS_SEND_A_CLONE_CTRANSID
+	_BTRFS_SEND_A_CLONE_PATH
+	_BTRFS_SEND_A_CLONE_OFFSET
+	_BTRFS_SEND_A_CLONE_LEN
+
+	__BTRFS_SEND_A_MAX
+)
+const _BTRFS_SEND_A_MAX = __BTRFS_SEND_A_MAX - 1

subvolume.go

@@ -17,7 +17,7 @@ func checkSubVolumeName(name string) bool {
 func IsSubVolume(path string) (bool, error) {
 	var st syscall.Stat_t
 	if err := syscall.Stat(path, &st); err != nil {
-		return false, err
+		return false, &os.PathError{Op: "stat", Path: path, Err: err}
 	}
 	if st.Ino != firstFreeObjectid ||
 		st.Mode&syscall.S_IFMT != syscall.S_IFDIR {
@@ -124,7 +124,7 @@ func SnapshotSubVolume(subvol, dst string, ro bool) error {
 	// TODO: make SnapshotSubVolume a method on FS to use existing fd
 	f, err := openDir(subvol)
 	if err != nil {
-		return err
+		return fmt.Errorf("cannot open dest dir: %v", err)
 	}
 	defer f.Close()
 	args := btrfs_ioctl_vol_args_v2{
@@ -140,7 +140,10 @@ func SnapshotSubVolume(subvol, dst string, ro bool) error {
 	//	args.qgroup_inherit = inherit
 	//}
 	copy(args.name[:], newName)
-	return iocSnapCreateV2(fdst, &args)
+	if err := iocSnapCreateV2(fdst, &args); err != nil {
+		return fmt.Errorf("ioc failed: %v", err)
+	}
+	return nil
 }
 
 func ListSubVolumes(path string) ([]Subvolume, error) {

utils.go

@@ -14,7 +14,7 @@ import (
 func isBtrfs(path string) (bool, error) {
 	var stfs syscall.Statfs_t
 	if err := syscall.Statfs(path, &stfs); err != nil {
-		return false, err
+		return false, &os.PathError{Op: "statfs", Path: path, Err: err}
 	}
 	return stfs.Type == SuperMagic, nil
 }