.\" Access Control Lists manual pages
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.\" (C) 2002 Andreas Gruenbacher, <a.gruenbacher@bestbits.at>
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.Dd March 23, 2002
.Dt ACL_CHECK 3
.Os "Linux ACL"
.Sh NAME
.Nm acl_check
.Nd check an ACL for validity
.Sh LIBRARY
Linux Access Control Lists library (libacl, \-lacl).
.Sh SYNOPSIS
.In sys/types.h
.In acl/libacl.h
.Ft int
.Fn acl_check "acl_t acl" "int *last"
.Sh DESCRIPTION
The
.Fn acl_check
function checks the ACL referred to by the argument
.Va acl
for validity.
.Pp
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.
.Pp
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.
.Pp
If the ACL referred to by
.Va acl
is invalid,
.Fn acl_check
returns a positive error code that indicates which type of error was detected.
The following symbolic error codes are defined:
.Bl -tag -width ACL_DUPLICATE_ERROR.
.It ACL_MULTI_ERROR
The ACL contains multiple entries that have a tag type
that may occur at most once.
.It 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.
.It ACL_MISS_ERROR
A required entry is missing.
.It ACL_ENTRY_ERROR
The ACL contains an invalid entry tag type.
.El
.Pp
The
.Fn acl_error
function can be used to translate error codes to text messages.
.Pp
In addition, if the pointer
.Va last
is not
.Li NULL ,
.Fn acl_check
assigns the number of the ACL entry at which the error was detected to
the value pointed to by
.Va last .
Entries are numbered starting with zero, in the order in which they would be
returned by the
.Fn acl_get_entry
function.
.Sh RETURN VALUE
If successful, the
.Fn acl_check
function returns
.Li 0
if the ACL referred to by
.Va acl
is valid, and a positive error code if the ACL is invalid. Otherwise, a
value of
.Li -1
is returned and the global variable
.Va errno
is set to indicate the error.
.Sh ERRORS
If any of the following conditions occur, the
.Fn acl_check
function returns
.Li -1
and sets
.Va errno
to the corresponding value:
.Bl -tag -width Er
.It Bq Er EINVAL
The argument
.Va acl
is not a valid pointer to an ACL.
.El
.Sh STANDARDS
This is a non-portable, Linux specific extension to the ACL manipulation
functions defined in IEEE Std 1003.1e draft 17 (\(lqPOSIX.1e\(rq, abandoned).
.Sh SEE ALSO
.Xr acl_valid 3 ,
.Xr acl 5
.Sh AUTHOR
Written by
.An "Andreas Gruenbacher" Aq a.gruenbacher@bestbits.at .
