int rfio_chmod (const char *path, mode_t mode);
int rfio_fchmod (int s, mode_t mode);
rfio_fchmod is identical to rfio_chmod but works on the file descriptor s returned by rfio_open.
The effective user ID of the process must match the owner of the file or be super-user. If a directory is writable and has the sticky bit set, files/directories within that directory can be removed or renamed only if:
the effective user ID of the requestor matches the owner ID of the file or
the effective user ID of the requestor matches the owner ID of the directory or
the file is writable by the requestor or
the requestor is super-user.