The f_readdir function reads a directory item, informations about the object. All items in the directory can be read in sequence by f_readdir function calls. Dot entries ("." and "..") in the sub-directory are filtered out and they will never appear in the read items. When all directory items have been read and no item to read, a nul string is stored into the fno->fname[] without any error. When a null pointer is given to the fno, the read index of the directory object is rewinded.
-When support of long file name (LFN) is enabled, a member altname[] is defined in the file information structure to store the short file name of the object. In case of the some conditions listed below, short file name is stored into the fname[] and altname[] has a null string.
+When support of long file name (LFN) is enabled, a member altname[] is defined in the file information structure to store the short file name of the object. If the long file name is not accessible due to some reason listed below, short file name is stored to the fname[] and altname[] has a null string.
There is a problem on reading a directory of exFAT volume. The exFAT does not support short file name. This means no name can be returned on the condition above. If it is the case, a "?" is returned as file name to indicate that the object is not accessible. To avoid this problem, configure FatFs _LFN_UNICODE = 1 and _MAX_LFN = 255 to support the full feature of LFN specification.
+There is a problem on reading a directory of exFAT volume. The exFAT does not support short file name. This means no name can be returned on the condition above. If it is the case, "?" is returned into the fname[] to indicate that the object is not accessible. To avoid this problem, configure FatFs FF_LFN_UNICODE >= 1 and FF_MAX_LFN == 255 to support the full feature of LFN specification.