Fix bug loading emptyfile

auxlib.go

@@ -3,6 +3,7 @@ package lua
 import (
 	"bufio"
 	"fmt"
+	"io"
 	"os"
 	"strings"
 )
@@ -357,7 +358,7 @@ func (ls *LState) LoadFile(path string) (*LFunction, error) {
 	reader := bufio.NewReader(file)
 	// get the first character.
 	c, err := reader.ReadByte()
-	if err != nil {
+	if err != nil && err != io.EOF {
 		return nil, newApiErrorE(ApiErrorFile, err)
 	}
 	if c == byte('#') {
@@ -368,7 +369,15 @@ func (ls *LState) LoadFile(path string) (*LFunction, error) {
 			return nil, newApiErrorE(ApiErrorFile, err)
 		}
 	}
-	reader.UnreadByte()
+
+	if err != io.EOF {
+		// if the file is not empty,
+		// unread the first character of the file or newline character(readBufioLine's last byte).
+		err = reader.UnreadByte()
+		if err != nil {
+			return nil, newApiErrorE(ApiErrorFile, err)
+		}
+	}
 
 	return ls.Load(reader, path)
 }

auxlib_test.go

@@ -315,3 +315,19 @@ print("hello")
 	_, err = L.LoadFile(tmpFile.Name())
 	errorIfNotNil(t, err)
 }
+
+func TestLoadFileForEmptyFile(t *testing.T) {
+	tmpFile, err := ioutil.TempFile("", "")
+	errorIfNotNil(t, err)
+
+	defer func() {
+		tmpFile.Close()
+		os.Remove(tmpFile.Name())
+	}()
+
+	L := NewState()
+	defer L.Close()
+
+	_, err = L.LoadFile(tmpFile.Name())
+	errorIfNotNil(t, err)
+}