fix: fota.file写入过程有错误导致死机

luat/modules/luat_lib_fota.c

@@ -144,9 +144,9 @@ static int l_fota_file(lua_State* L)
         lua_pushinteger(L, 0);
         return 3;
     }
-    size_t len  = 0;
+    int len  = 0;
     while (1) {
-        len = luat_fs_fread(buff + len, BUFF_SIZE - len, 1, fd);
+        len = luat_fs_fread(buff , BUFF_SIZE, 1, fd);
         if (len < 1) {
             // EOF 结束了
             break;
@@ -155,12 +155,6 @@ static int l_fota_file(lua_State* L)
         if (result < 0) {
             break;
         }
-        result = len;
-        if (len >= BUFF_SIZE) {
-            LLOGD("too many data to write! bug??");
-            result = -7;
-            break;
-        }
     }
     luat_heap_free(buff);
     luat_fs_fclose(fd);