ACL_GET_QUALIFIER

Section: C Library Functions (3)
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BSD mandoc
Linux ACL

NAME

acl_get_qualifier - retrieve the qualifier from an ACL entry

LIBRARY

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

SYNOPSIS

In sys/types.h In sys/acl.h Ft void * Fn acl_get_qualifier acl_entry_t entry_d

DESCRIPTION

The Fn 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 Fn 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 Fn 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, Fn 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 Fn acl_free with the void value returned by Fn 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 Fn acl_get_qualifier function returns (void *)NULL and sets errno to the corresponding value:

Bq Er 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.
Bq Er 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 (lqPOSIX.1erq, abandoned)

AUTHOR

Derived from the FreeBSD manual pages written by An Robert N M Watson Aq rwatson@FreeBSD.org , and adapted for Linux by An Andreas Gruenbacher Aq a.gruenbacher@bestbits.at .