ACL\_CHECK(3) Library Functions Manual ACL\_CHECK(3)

# [NAME](#NAME)

`acl_check` — check an ACL for validity

# [LIBRARY](#LIBRARY)

Linux Access Control Lists library (libacl, -lacl).

# [SYNOPSIS](#SYNOPSIS)

`#include <sys/types.h>`  
`#include <acl/libacl.h>`

`int`  
`acl_check`(`acl_t acl`, `int *last`);

# [DESCRIPTION](#DESCRIPTION)

The [`acl_check`](#acl_check)() function checks the ACL referred to by the argument `acl` for validity.

The three required entries ACL\_USER\_OBJ, ACL\_GROUP\_OBJ, and ACL\_OTHER must exist exactly once in the ACL. If the ACL contains any ACL\_USER or ACL\_GROUP entries, then an ACL\_MASK entry is also required. The ACL may contain at most one ACL\_MASK entry.

The user identifiers must be unique among all entries of type ACL\_USER. The group identifiers must be unique among all entries of type ACL\_GROUP.

If the ACL referred to by `acl` is invalid, [`acl_check`](#acl_check~2)() returns a positive error code that indicates which type of error was detected. The following symbolic error codes are defined:

ACL\_MULTI\_ERROR

The ACL contains multiple entries that have a tag type that may occur at most once.

ACL\_DUPLICATE\_ERROR

The ACL contains multiple ACL\_USER entries with the same user ID, or multiple ACL\_GROUP entries with the same group ID.

ACL\_MISS\_ERROR

A required entry is missing.

ACL\_ENTRY\_ERROR

The ACL contains an invalid entry tag type.

The [`acl_error`](#acl_error)() function can be used to translate error codes to text messages.

In addition, if the pointer `last` is not `NULL`, [`acl_check`](#acl_check~3)() assigns the number of the ACL entry at which the error was detected to the value pointed to by `last`. Entries are numbered starting with zero, in the order in which they would be returned by the [`acl_get_entry`](#acl_get_entry)() function.

# [RETURN VALUE](#RETURN_VALUE)

If successful, the `acl_check`() function returns `0` if the ACL referred to by `acl` is valid, and a positive error code if the ACL is invalid. Otherwise, a value of `-1` is returned and the global variable `errno` is set to indicate the error.

# [ERRORS](#ERRORS)

If any of the following conditions occur, the `acl_check`() function returns `-1` and sets `errno` to the corresponding value:

\[[`EINVAL`](#EINVAL)]

The argument `acl` is not a valid pointer to an ACL.

# [STANDARDS](#STANDARDS)

This is a non-portable, Linux specific extension to the ACL manipulation functions defined in IEEE Std 1003.1e draft 17 (“POSIX.1e”, abandoned).

# [SEE ALSO](#SEE_ALSO)

[acl\_valid(3)](/man/os/acl/acl_valid.3), [acl(5)](/man/os/acl/acl.5)

# [AUTHOR](#AUTHOR)

Written by Andreas Gruenbacher ⟨andreas.gruenbacher@gmail.com⟩.

March 23, 2002 Linux ACL

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Document: acl_check(3) from acl 2.4.0-r3 (Chainguard OS)
Source: https://git.savannah.nongnu.org/git/acl.git