acl_dup —
duplicate an ACL
Standard C Library (libc, -lc)
The acl_dup() function returns a pointer to a copy of
  the ACL pointed to by the argument acl.
This function may cause memory to be allocated. The caller should
    free any releasable memory, when the new ACL is no longer required, by
    calling acl_free(3) with the
    (void*)acl_t as an argument.
Any existing ACL pointers that refer to the ACL referred to by
    acl shall continue to refer to the ACL.
FreeBSD's support for POSIX.1e interfaces and features
  is still under development at this time.
Upon successful completion, this function shall return a pointer to the
  duplicate ACL. Otherwise, a value of (acl_t)NULL shall
  be returned, and errno shall be set to indicate the
  error.
If any of the following conditions occur, the acl_init()
  function shall return a value of (acl_t)NULL and set
  errno to the corresponding value:
  - [EINVAL]
- Argument acl does not point to a valid ACL.
- [ENOMEM]
- The acl_t to be returned requires more memory than
      is allowed by the hardware or system-imposed memory management
      constraints.
POSIX.1e is described in IEEE POSIX.1e draft 17. Discussion of the draft
  continues on the cross-platform POSIX.1e implementation mailing list. To join
  this list, see the FreeBSD POSIX.1e implementation
  page for more information.
POSIX.1e support was introduced in FreeBSD 4.0, and
  development continues.