I see the following behaviour on NuttX 7.26, where I have SD card mounted on /flash and a directory called "frm" on it:
opendir("/flash") returns (DIR *) 0x1000c580
opendir("/flash/") returns (DIR *) 0x1000c5d0
opendir("/flash/frm") returns (DIR *) 0x1000c620
opendir("/flash/frm/") returns (DIR *) 0x0
From POSIX specs for opendir(): "A pathname ... that ends with one or more trailing slashes shall be resolved as if a single dot character ( '.' ) were appended to the pathname."
So for mount points, opendir() works correctly, but for FAT32 filesystem it fails to open directory if the path has a trailing slash. I'm not quite sure how to cleanly fix this. Stripping the trailing slash in opendir() would require allocating a separate buffer, while fixing it in the FAT32 code seems somewhat complex due to the short/long filename logic.
It is not a big issue for me, I'm just going to fix it on the application side. But still a small portability and standards compliance issue.
NOTE: You would not see this problem if you call opendir() indirectly in NSH (like 'ls -R /') because NSH contains logic to remove trailing '/' characters from paths.
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