ACL_GET_QUALIFIER(3)

NAME
acl_get_qualifier - retrieve the qualifier from an ACL entry

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

SYNOPSIS
#include <sys/types.h>
#include <sys/acl.h>
void *
acl_get_qualifier(acl_entry_t entry_d);

DESCRIPTION
The acl_get_qualifier() function retrieves the qualifier from the ACL entry indicated by the argument entry_d into working storage and returns a pointer to that storage.

If the value of the tag type in the ACL entry referred to by entry_d is ACL_USER, then the value returned by acl_get_qualifier() is a pointer to type uid_t. If the value of the tag type in the ACL entry referred to by entry_d is ACL_GROUP, then the value returned by acl_get_qualifier() is a pointer to type gid_t. If the tag type in the ACL entry referred to by entry_d is a tag type for which a qualifier is not supported, acl_get_qualifier() returns a value of (void *)NULL and the function fails. Subsequent operations using the returned pointer operate on an independent copy of the qualifier in working storage, and will not change the qualifier of the ACL entry.

This function may cause memory to be allocated. The caller should free any releasable memory, when the new qualifier is no longer required, by calling acl_free() with the void * value returned by acl_get_qualifier() as an argument.

The argument entry_d and any other ACL entry descriptors that refer to entries within the ACL containing the entry referred to by entry_d continue to refer to those entries. The order of all existing entries in the ACL containing the entry referred to by entry_d remains unchanged.

RETURN VALUE
On success, the function returns a pointer to the tag qualifier that was retrieved into ACL working storage. On error, a value of (void *)NULL is returned and errno is set appropriately.

ERRORS
If any of the following conditions occur, the acl_get_qualifier() function returns (void *)NULL and sets errno to the corresponding value:

[EINVAL]
    The argument entry_d is not a valid descriptor for an ACL entry.

    The value of the tag type in the ACL entry referenced by the argument entry_d is neither ACL_USER nor ACL_GROUP.

[ENOMEM]
    The value to be returned requires more memory than is allowed by the hardware or system-imposed memory management constraints.

STANDARDS
IEEE Std 1003.1e draft 17 (“POSIX.1e”, abandoned)

SEE ALSO
acl_create_entry(3), acl_free(3), acl_get_entry(3), acl_get_permset(3), acl_get_tag_type(3), acl_set_permset(3), acl_set_qualifier(3), acl_set_tag_type(3), acl(5)

AUTHOR
Derived from the FreeBSD manual pages written by Robert N M Watson <rwatson@FreeBSD.org>, and adapted for Linux by Andreas Gruenbacher <andreas.gruenbacher@gmail.com>.