Linux Access Control Lists library (libacl, -lacl).  The function
sets  the qualifier of the ACL entry indicated by the argument to
the value referred to by the argument If the  value  of  the  tag
type  in the ACL entry referred to by is ACL_USER, then the value
referred to by shall be of type If the value of the tag  type  in
the  ACL  entry  referred  to by is ACL_GROUP, then the value re‐
ferred to by shall be of type If the value of the tag type in the
ACL entry referred to by is a tag type for which a  qualifier  is
not  supported, returns an error.  Any ACL entry descriptors that
refer to the entry referred to by continue to refer to  that  en‐
try.  This  function may cause memory to be allocated. The caller
should free any releasable memory, when the ACL is no longer  re‐
quired, by calling with a pointer to the ACL as argument.  If any
of  the following conditions occur, the function returns and sets
to the corresponding value: The argument is not a valid  descrip‐
tor for an ACL entry.  The value of the tag type in the ACL entry
referenced  by  the  argument  is neither ACL_USER nor ACL_GROUP.
The value pointed to by the argument is not valid.  The  function
is  unable to allocate the memory required for the ACL qualifier.
IEEE Std 1003.1e draft 17 (“POSIX.1e”,  abandoned)  Derived  from
the FreeBSD manual pages written by and adapted for Linux by