The DIR structure is used for the work area to read a directory by f_oepndir, f_readdir function. There is no member that can be changed by application.
typedef struct _DIR_ { FATFS* fs; /* Pointer to the owner file system object */ WORD id; /* Owner file system mount ID */ WORD index; /* Current read/write index number */ DWORD sclust; /* Table start cluster (0:Static table) */ DWORD clust; /* Current cluster */ DWORD sect; /* Current sector */ BYTE* dir; /* Pointer to the current SFN entry in the win[] */ BYTE* fn; /* Pointer to the SFN (in/out) {file[8],ext[3],status[1]} */ #if _USE_LFN WCHAR* lfn; /* Pointer to the LFN working buffer */ WORD lfn_idx; /* Last matched LFN index (0xFFFF:No LFN) */ #endif } DIR;