fix: update maxHeaderSize to 22 #1800 (#1877)

Author: joshua-goldstein

structs.go

@@ -72,8 +72,8 @@ type header struct {
 
 const (
 	// Maximum possible size of the header. The maximum size of header struct will be 18 but the
-	// maximum size of varint encoded header will be 21.
-	maxHeaderSize = 21
+	// maximum size of varint encoded header will be 22.
+	maxHeaderSize = 22
 )
 
 // Encode encodes the header into []byte. The provided []byte should be atleast 5 bytes. The

structs_test.go

@@ -0,0 +1,21 @@
+package badger
+
+import (
+	"math"
+	"reflect"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+// Regression test for github.com/dgraph-io/badger/pull/1800
+func TestLargeEncode(t *testing.T) {
+	var headerEnc [maxHeaderSize]byte
+	h := header{math.MaxUint32, math.MaxUint32, math.MaxUint64, math.MaxUint8, math.MaxUint8}
+	require.NotPanics(t, func() { _ = h.Encode(headerEnc[:]) })
+}
+
+func TestNumFieldsHeader(t *testing.T) {
+	// maxHeaderSize must correspond with any changes made to header
+	require.Equal(t, 5, reflect.TypeOf(header{}).NumField())
+}