ENOTDIR vs ENOENT for invalid path prefix

[FrankHB]

Some POSIX functions (e.g. open, unlink, opendir, mkdir) requires setting errno to ENOTDIR rather than ENOENT when "a component of the path prefix names an existing file that is neither a directory nor a symbolic link to a directory". They are implemented by function _FAT_directory_entryFromPath in libfat, which does not provide right information to distinguish the accurate errors:

                if (found && !(entry->entryData[DIR_ENTRY_attributes] & ATTRIB_DIR) && (nextPathPosition != NULL)) {
                    // Make sure that we aren't trying to follow a file instead of a directory in the path
                    found = false;
                }

Note that the implementation like _FAT_open_r is not sufficient, because it only tests the last component (not prefix) of the path:

                if (!_FAT_directory_entryFromPath (partition, &dirEntry, path, pathEnd) ||
                    !_FAT_directory_isDirectory(&dirEntry)) {
                    _FAT_unlock(&partition->lock);
                    r->_errno = ENOTDIR;
                    return -1;
                }