acl_calc_mask - calculate the file group class mask
Linux Access Control Lists library (libacl, -lacl).
The acl_calc_mask() function calculates and sets the permissions
associated with the ACL_MASK ACL entry of the ACL referred to by acl_p.
The value of the new permissions is the union of the permissions granted
by all entries of tag type ACL_GROUP, ACL_GROUP_OBJ, or ACL_USER. If the
ACL referred to by acl_p already contains an ACL_MASK entry, its
permissions are overwritten; if it does not contain an ACL_MASK entry,
one is added.
If the ACL referred to by acl_p does not contain enough space for the new
ACL entry, then additional working storage may be allocated. If the
working storage cannot be increased in the current location, then it may
be relocated and the previous working storage is released and a pointer
to the new working storage is returned via acl_p.
The order of existing entries in the ACL is undefined after this
Any existing ACL entry descriptors that refer to entries in the ACL
continue to refer to those entries. Any existing ACL pointers that refer
to the ACL referred to by acl_p continue to refer to the ACL.
The acl_calc_mask() function returns the value 0 if successful; otherwise
the value -1 is returned and the global variable errno is set to indicate
If any of the following conditions occur, the acl_calc_mask() function
returns -1 and sets errno to the corresponding value:
[EINVAL] The argument acl is not a valid pointer to an ACL.
[ENOMEM] The acl_calc_mask() function is unable to allocate the
memory required for an ACL_MASK ACL entry.
IEEE Std 1003.1e draft 17 (“POSIX.1e”, abandoned)
acl_check(3), acl_get_entry(3), acl_valid(3), acl(5)
Derived from the FreeBSD manual pages written by Robert N M Watson
〈rwatson@FreeBSD.org〉, and adapted for Linux by Andreas Gruenbacher