Linux Access Control Lists library (libacl, -lacl).  The function
return the size, in bytes, of the buffer required to hold the ex‐
portable,  contiguous,  persistent  form of the ACL pointed to by
the argument when converted by Any existing ACL entry descriptors
that refer to entries in continue to refer to the  same  entries.
Any  existing  ACL  pointers that refer to the ACL referred to by
continue to refer to the ACL. The order of ACL entries within re‐
mains unchanged.  On success, the function returns  the  size  in
bytes  of the contiguous, persistent form of the ACL. On error, a
value of is returned and is set appropriately.   If  any  of  the
following  conditions  occur, the function returns a value of and
sets to the corresponding value: The  argument  is  not  a  valid
pointer  to an ACL.  IEEE Std 1003.1e draft 17 (“POSIX.1e”, aban‐
doned) Derived from the  FreeBSD  manual  pages  written  by  and
adapted for Linux by