Merge pull request #200 from xtrafrancyz/master

Fix and improvements to mca

save/region/mca.go

@@ -78,14 +78,19 @@ func Load(f io.ReadWriteSeeker) (r *Region, err error) {
 }
 
 // Create open .mca file with os.O_CREATE|os. O_EXCL, and init the region
-func Create(name string) (r *Region, err error) {
-	r = new(Region)
-	r.sectors = make(map[int32]bool)
-
-	r.f, err = os.OpenFile(name, os.O_CREATE|os.O_RDWR|os.O_EXCL, 0666)
+func Create(name string) (*Region, error) {
+	f, err := os.OpenFile(name, os.O_CREATE|os.O_RDWR|os.O_EXCL, 0666)
 	if err != nil {
 		return nil, err
 	}
+	return CreateWriter(f)
+}
+
+// CreateWriter init the region
+func CreateWriter(f io.ReadWriteSeeker) (r *Region, err error) {
+	r = new(Region)
+	r.sectors = make(map[int32]bool)
+	r.f = f
 
 	// write the offsets
 	err = binary.Write(r.f, binary.BigEndian, &r.offsets)
@@ -152,7 +157,7 @@ func (r *Region) ReadSector(x, z int) (data []byte, err error) {
 
 // WriteSector write Chunk data into region file
 func (r *Region) WriteSector(x, z int, data []byte) error {
-	need := int32(len(data)+4)/4096 + 1
+	need := int32((len(data) + 4 + 4096 - 1) / 4096)
 	n, now := sectorLoc(r.offsets[z][x])
 
 	// maximum chunk size is 1MB
@@ -212,6 +217,23 @@ func (r *Region) ExistSector(x, z int) bool {
 	return r.offsets[z][x] != 0
 }
 
+// PadToFullSector writes zeros to the end of the file to make size a multiple of 4096
+// Legacy versions of Minecraft require this
+// Need to be called right before Close
+func (r *Region) PadToFullSector() error {
+	size, err := r.f.Seek(0, io.SeekEnd)
+	if err != nil {
+		return err
+	}
+	if size%4096 != 0 {
+		_, err = r.f.Write(make([]byte, 4096-size%4096))
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 func (r *Region) findSpace(need int32) (n int32) {
 	for i := int32(0); i < need; i++ {
 		if r.sectors[n+i] {

save/region/mca_test.go

@@ -3,8 +3,12 @@ package region
 import (
 	"bytes"
 	"compress/zlib"
-	"github.com/Tnze/go-mc/nbt"
+	"io"
+	"math/rand"
+	"os"
 	"testing"
+
+	"github.com/Tnze/go-mc/nbt"
 )
 
 func TestIn(t *testing.T) {
@@ -95,3 +99,73 @@ func TestCountChunks(t *testing.T) {
 	}
 	t.Logf("chunk count: %d", count)
 }
+
+func TestWriteSectors(t *testing.T) {
+	temp, err := os.CreateTemp("", "region*.mca")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() {
+		if err := temp.Close(); err != nil {
+			t.Error(err)
+		}
+		if err := os.Remove(temp.Name()); err != nil {
+			t.Error(err)
+		}
+	}()
+	region, err := CreateWriter(temp)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expectedSectorsNum := 2
+	for idx, test := range []struct{ size, sectors int }{
+		{0, 1},
+		{1000, 1},
+		{4091, 1},
+		{4092, 1},
+		{4093, 2},
+		{5000, 2},
+	} {
+		expectedSectorsNum += test.sectors
+
+		data := make([]byte, test.size)
+		rand.Read(data)
+		if err = region.WriteSector(idx, 0, data); err != nil {
+			t.Fatal("write sector", err)
+		}
+		if len(region.sectors) != expectedSectorsNum {
+			t.Errorf("wrong region sector count. Got: %d, Want: %d", len(region.sectors), expectedSectorsNum)
+		}
+		
+		if read, err := region.ReadSector(idx, 0); err != nil {
+			t.Fatal("read sector", err)
+		} else if !bytes.Equal(data, read) {
+			t.Fatal("read corrupted sector data")
+		}
+	}
+
+	// reset file
+	if _, err = temp.Seek(0, io.SeekStart); err != nil {
+		t.Fatal(err)
+	}
+
+	// Test load
+	region, err = Load(temp)
+	if err != nil {
+		t.Fatalf("load region: %v", err)
+	}
+	if len(region.sectors) != expectedSectorsNum {
+		t.Fatalf("read sector count missmatch. Got: %d, Want: %d", len(region.sectors), expectedSectorsNum)
+	}
+
+	// Test padding
+	if err = region.PadToFullSector(); err != nil {
+		t.Fatal(err)
+	}
+	if stat, err := temp.Stat(); err != nil {
+		t.Fatal(err)
+	} else if stat.Size()%4096 != 0 {
+		t.Fatalf("wrong file size. Got %d, Want: %d", stat.Size(), stat.Size()+(4096-stat.Size()%4096))
+	}
+}