fix ReadVarSize bug

bin.go

@@ -1022,9 +1022,10 @@ func ReadVarSize(src io.ByteReader) (_ int, err error) {
 		if err != nil {
 			return
 		}
+
 		if b >= 128 {
 			num |= uint64(b&127) << uint(i*7)
-			return
+			return int(num), nil
 		}
 		num |= uint64(b) << uint(i*7)
 	}

bin_test.go

@@ -669,3 +669,35 @@ func TestInt32(t *testing.T) {
 
 	fmt.Println(num)
 }
+
+func TestVarSize(t *testing.T) {
+	var (
+		buf = bytes.NewBuffer(nil)
+
+		nums = []int{
+			127,                 // 7
+			16383,               // 14
+			2097151,             // 21
+			268435455,           // 28
+			34359738367,         // 35
+			4398046511103,       // 42
+			562949953421311,     // 49
+			72057594037927935,   // 56
+			9223372036854775807, // 63
+		}
+	)
+
+	for _, num := range nums {
+		WriteVarSize(buf, num)
+
+		decoded, err := ReadVarSize(buf)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if decoded != num {
+			t.Fatalf("num %d decoded as %d\n", num, decoded)
+		}
+		buf.Reset()
+	}
+}