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ACL_CHECK(3) Library Functions Manual ACL_CHECK(3)


acl_checkcheck an ACL for validity


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


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

acl_check(acl_t acl, int *last);


The () 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, () returns a positive error code that indicates which type of error was detected. The following symbolic error codes are defined:

The ACL contains multiple entries that have a tag type that may occur at most once.
The ACL contains multiple ACL_USER entries with the same user ID, or multiple ACL_GROUP entries with the same group ID.
A required entry is missing.
The ACL contains an invalid entry tag type.

The () function can be used to translate error codes to text messages.

In addition, if the pointer last is not NULL, () 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 () function.


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.


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

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


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


acl_valid(3), acl(5)


Written by Andreas Gruenbacher ⟨⟩.

March 23, 2002 Linux ACL