How do I add _findfirst and _findnext functions to LVGL

My projects
1

If _findfirst and _findnext are not found in lv_fs.c, how do I implement the find file function interface

typedef struct _lv_fs_drv_t {
    char letter;
    uint16_t file_size;
    uint16_t rddir_size;
    bool (*ready_cb)(struct _lv_fs_drv_t * drv);

    lv_fs_res_t (*open_cb)(struct _lv_fs_drv_t * drv, void * file_p, const char * path, lv_fs_mode_t mode);
    lv_fs_res_t (*close_cb)(struct _lv_fs_drv_t * drv, void * file_p);
    lv_fs_res_t (*remove_cb)(struct _lv_fs_drv_t * drv, const char * fn);
    lv_fs_res_t (*read_cb)(struct _lv_fs_drv_t * drv, void * file_p, void * buf, uint32_t btr, uint32_t * br);
    lv_fs_res_t (*write_cb)(struct _lv_fs_drv_t * drv, void * file_p, const void * buf, uint32_t btw, uint32_t * bw);
    lv_fs_res_t (*seek_cb)(struct _lv_fs_drv_t * drv, void * file_p, uint32_t pos);
    lv_fs_res_t (*tell_cb)(struct _lv_fs_drv_t * drv, void * file_p, uint32_t * pos_p);
    lv_fs_res_t (*trunc_cb)(struct _lv_fs_drv_t * drv, void * file_p);
    lv_fs_res_t (*size_cb)(struct _lv_fs_drv_t * drv, void * file_p, uint32_t * size_p);
    lv_fs_res_t (*rename_cb)(struct _lv_fs_drv_t * drv, const char * oldname, const char * newname);
    lv_fs_res_t (*free_space_cb)(struct _lv_fs_drv_t * drv, uint32_t * total_p, uint32_t * free_p);

    lv_fs_res_t (*dir_open_cb)(struct _lv_fs_drv_t * drv, void * rddir_p, const char * path);
    lv_fs_res_t (*dir_read_cb)(struct _lv_fs_drv_t * drv, void * rddir_p, char * fn);
    lv_fs_res_t (*dir_close_cb)(struct _lv_fs_drv_t * drv, void * rddir_p);

#if LV_USE_USER_DATA
    lv_fs_drv_user_data_t user_data; /**< Custom file user data */
#endif
} lv_fs_drv_t;