Add fuzz testing for Section encoding/decoding with multiple edge cases

2026-04-28 09:31:35 +02:00
parent ce0c58e7c5
commit 719a3bacd8
15 changed files with 289 additions and 65 deletions
@@ -0,0 +1,138 @@
+package level
+
+import (
+	"encoding/binary"
+	"errors"
+	"io"
+	"math"
+
+	"github.com/admin-else/strom/data"
+	"github.com/admin-else/strom/proto_base"
+	"github.com/admin-else/strom/util"
+)
+
+type BlockState struct {
+	Id         string
+	Properties map[string]string
+}
+
+const (
+	ChunkWidth            = 16
+	ChunkColumns          = ChunkWidth * ChunkWidth
+	BlocksPerChunkSection = ChunkWidth * ChunkWidth * ChunkWidth
+	ChunkBiomesWidth      = 4
+	BiomesPerChunkSection = ChunkBiomesWidth * ChunkBiomesWidth * ChunkBiomesWidth
+)
+
+type Section struct {
+	BlockCount     int16
+	Blocks, Biomes *Storage
+}
+
+func MakeBiomeFormat(version string) StorageFormat {
+	directBpe := uint8(math.Ceil(math.Log2(float64(len(data.BiomesForVersion(version))))))
+	return StorageFormat{
+		AvailableBpes: []uint8{0, 1, 2, 3, directBpe},
+		BiggestDirect: true,
+		Len:           BiomesPerChunkSection,
+	}
+}
+
+func MakeBlockFormat(version string) StorageFormat {
+	directBpe := uint8(math.Ceil(math.Log2(float64(len(data.BlocksForVersion(version))))))
+	return StorageFormat{
+		AvailableBpes: []uint8{0, 1, 2, 3, directBpe},
+		BiggestDirect: true,
+		Len:           BiomesPerChunkSection,
+	}
+}
+
+var BadPaletteLenErr = errors.New("bad palette length")
+
+func ReadSectionStorage(r io.Reader, format StorageFormat) (s *Storage, err error) {
+	var bpe uint8
+	err = binary.Read(r, binary.BigEndian, &bpe)
+	if err != nil {
+		return
+	}
+	var pallette []int32
+	if bpe == 0 {
+		var v int32
+		v, err = proto_base.DecodeVarInt(r)
+		if err != nil {
+			return
+		}
+		pallette = []int32{v}
+	} else if !util.IsLastElement(format.AvailableBpes, bpe) {
+		var paletteLen int32
+		paletteLen, err = proto_base.DecodeVarInt(r)
+		if err != nil {
+			return
+		}
+		if paletteLen < 0 {
+			err = BadPaletteLenErr
+			return
+		}
+		for range pallette {
+			var v int32
+			v, err = proto_base.DecodeVarInt(r)
+			if err != nil {
+				return
+			}
+			pallette = append(pallette, v)
+		}
+	}
+	return format.ImportFromReader(r, bpe, pallette)
+}
+
+func WriteSectionStorage(w io.Writer, s *Storage) (err error) {
+	err = binary.Write(w, binary.BigEndian, s.bpe)
+	if err != nil {
+		return
+	}
+	if s.bpe == 0 {
+		err = proto_base.EncodeVarInt(w, s.palette[0])
+		if err != nil {
+			return
+		}
+	} else if !util.IsLastElement(s.format.AvailableBpes, s.bpe) {
+		err = proto_base.EncodeVarInt(w, int32(len(s.palette)))
+		if err != nil {
+			return
+		}
+		for _, v := range s.palette {
+			err = proto_base.EncodeVarInt(w, v)
+			if err != nil {
+				return
+			}
+		}
+	}
+	return binary.Write(w, binary.BigEndian, s.data)
+}
+
+func SectionDecodePacket(r io.Reader, version string) (s Section, err error) {
+	s = Section{}
+	err = binary.Read(r, binary.BigEndian, &s.BlockCount)
+	if err != nil {
+		return
+	}
+	s.Blocks, err = ReadSectionStorage(r, MakeBlockFormat(version))
+	if err != nil {
+		return
+	}
+	s.Biomes, err = ReadSectionStorage(r, MakeBiomeFormat(version))
+	return
+}
+
+func SectionEncodePacket(w io.Writer, s Section) (err error) {
+	err = binary.Write(w, binary.BigEndian, s.BlockCount)
+	if err != nil {
+		return
+	}
+	err = WriteSectionStorage(w, s.Blocks)
+	if err != nil {
+		return
+	}
+	err = WriteSectionStorage(w, s.Biomes)
+	return
+}