Support v29 blocks

common/block.go

@@ -92,6 +92,132 @@ type posBuf struct {
 	Pos  int
 }
 
+type bigEndian struct {
+	data []byte
+	err  error
+}
+
+func (be *bigEndian) Err() error {
+	return be.err
+}
+
+func (be *bigEndian) u8() uint8 {
+	if be.err != nil {
+		return 0
+	}
+	if len(be.data) >= 1 {
+		x := be.data[0]
+		be.data = be.data[1:]
+		return x
+	}
+	be.err = ErrBlockTruncated
+	return 0
+}
+
+func (be *bigEndian) u16() uint16 {
+	if be.err != nil {
+		return 0
+	}
+	if len(be.data) >= 2 {
+		x := binary.BigEndian.Uint16(be.data)
+		be.data = be.data[2:]
+		return x
+	}
+	be.err = ErrBlockTruncated
+	return 0
+}
+
+func (be *bigEndian) u32() uint32 {
+	if be.err != nil {
+		return 0
+	}
+	if len(be.data) >= 4 {
+		x := binary.BigEndian.Uint32(be.data)
+		be.data = be.data[4:]
+		return x
+	}
+	be.err = ErrBlockTruncated
+	return 0
+}
+
+func (be *bigEndian) str(l int) string {
+	if be.err != nil {
+		return ""
+	}
+	if len(be.data) >= l {
+		s := string(be.data[:l])
+		be.data = be.data[l:]
+		return s
+	}
+	be.err = ErrBlockTruncated
+	return ""
+}
+
+func decode29(data []byte, colors *Colors) (*DecodedBlock, error) {
+
+	dec, err := zstd.NewReader(nil)
+	if err != nil {
+		return nil, err
+	}
+
+	content, err := dec.DecodeAll(data, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	be := bigEndian{data: content}
+
+	_ = be.u8()  // flags
+	_ = be.u16() // lightning_complete
+	_ = be.u32() // timestamp
+	_ = be.u8()  // name_id_mapping_version
+
+	airID, ignoreID := int32(-1), int32(-1)
+	indexMap := make(map[int32]int32)
+	transparent := false
+	numNameIDMappings := be.u16()
+	for i := uint16(0); i < numNameIDMappings; i++ {
+		id := int32(be.u16())
+		name := be.str(int(be.u16()))
+		switch name {
+		case "air":
+			airID = id
+		case "ignore":
+			ignoreID = id
+		default:
+			if index, found := colors.NameIndex[name]; found {
+				indexMap[id] = index
+				if !transparent && colors.IsTransparent(index) {
+					transparent = true
+				}
+			} else {
+				logMissing(name)
+			}
+		}
+	}
+	_ = be.u8() // content_width
+	_ = be.u8() // params_width
+
+	if err := be.Err(); err != nil {
+		return nil, err
+	}
+
+	mapContent := make([]byte, 2*4096)
+	if len(be.data) < len(mapContent) {
+		return nil, ErrBlockTruncated
+	}
+	copy(mapContent, be.data)
+
+	return &DecodedBlock{
+		Version:     data[0],
+		Transparent: transparent,
+		MapContent:  mapContent,
+		AirID:       airID,
+		IgnoreID:    ignoreID,
+		IndexMap:    indexMap,
+	}, nil
+}
+
 func NewDecodedBlock(data []byte, colors *Colors) (db *DecodedBlock, err error) {
 
 	dataLen := len(data)
@@ -101,20 +227,12 @@ func NewDecodedBlock(data []byte, colors *Colors) (db *DecodedBlock, err error)
 
 	version := data[0]
 
-	//var mapContent := make([]byte, uncompressedLen)
-	var mapContent []byte
+	if version >= 29 {
+		return decode29(data, colors)
+	}
+
 	var offset int
 
-	if version >= 29 {
-		dec, err := zstd.NewReader(nil)
-		if err != nil {
-			return nil, err
-		}
-		mapContent, err = dec.DecodeAll(data[1:], nil)
-		if err != nil {
-			return nil, err
-		}
-	} else {
 	contentWidth := Min(int(data[2]), 2)
 	paramsWidth := Min(int(data[3]), 2)
 
@@ -143,7 +261,7 @@ func NewDecodedBlock(data []byte, colors *Colors) (db *DecodedBlock, err error)
 		return
 	}
 
-		mapContent = make([]byte, uncompressedLen)
+	mapContent := make([]byte, uncompressedLen)
 
 	var k int
 	k, err = io.ReadFull(zr, mapContent)
@@ -198,7 +316,6 @@ func NewDecodedBlock(data []byte, colors *Colors) (db *DecodedBlock, err error)
 			offset += 2 + 10*num
 		}
 	}
-	}
 
 	offset++
 	if offset+1 >= dataLen {