---
name: "acl_calc_mask"
section: "3"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["linux", "freebsd"]
url: "https://new.carta.tech/acl_calc_mask"
---

# acl\_calc\_mask(3)

calculate and set ACL mask permissions

## NAME

**acl\_calc\_mask** – calculate and set ACL mask permissions

## LIBRARY

Standard C Library (libc, -lc)

## SYNOPSIS

**#include \<sys/types.h\>**

**#include \<sys/acl.h\>**

*int*\

**acl\_calc\_mask**(*acl\_t \*acl\_p*);

## DESCRIPTION

The **acl\_calc\_mask**() function is a POSIX.1e call that calculates and set the permissions associated with the ACL\_MASK ACL entry of the ACL referred to by *acl\_p*.

The value of new permissions are the union of the permissions granted by the ACL\_GROUP, ACL\_GROUP\_OBJ, ACL\_USER tag types which match processes in the file group class contained in the ACL referred to by *acl\_p*.

If the ACL referred to by *acl\_p* already contains an ACL\_MASK entry, its permissions shall be overwritten; if it does not contain an ACL\_MASK entry, one shall be added.

## RETURN VALUES

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 the error.

## ERRORS

The **acl\_calc\_mask**() function fails if:

- \[EINVAL\]

  Argument *acl\_p* does not point to a pointer to a valid ACL.

## SEE ALSO

[acl(3)](/acl/3.md), [acl\_get\_entry(3)](/acl_get_entry/3.md), [acl\_valid(3)](/acl_valid/3.md), [posix1e(3)](/posix1e/3.md)

## STANDARDS

POSIX.1e is described in IEEE POSIX.1e draft 17.

## HISTORY

POSIX.1e support was introduced in FreeBSD 4.0. The **acl\_calc\_mask**() function was added in FreeBSD 5.0.

## AUTHORS

The **acl\_calc\_mask**() function was written by Chris D. Faulhaber ⟨*jedgar@fxp.org*⟩.