.\" Copyright (c) 2018 Yubico AB. All rights reserved.
.\" Use of this source code is governed by a BSD-style
.\" license that can be found in the LICENSE file.
.\"
.Dd $Mdocdate: November 27 2019 $
.Dt FIDO_CRED_EXCLUDE 3
.Os
.Sh NAME
.Nm fido_cred_exclude
.Nd appends a credential ID to a credential's list of excluded credentials
.Sh SYNOPSIS
.In fido.h
.Ft int
.Fn fido_cred_exclude "fido_cred_t *cred" "const unsigned char *ptr" "size_t len"
.Sh DESCRIPTION
The
.Fn fido_cred_exclude
function adds
.Fa ptr
to the list of credentials excluded by
.Fa cred ,
where
.Fa ptr
points to a credential ID of
.Fa len
bytes.
A copy of
.Fa ptr
is made, and no references to the passed pointer are kept.
If
.Fn fido_cred_exclude
fails, the existing list of excluded credentials is preserved.
.Pp
If
.Nm
returns success and
.Fa cred
is later passed to
.Xr fido_dev_make_cred 3
on a device that contains the credential
denoted by
.Fa ptr ,
then
.Xr fido_dev_make_cred 3
will fail.
.Pp
For the format of a FIDO 2 credential ID, please refer to the
Web Authentication (webauthn) standard.
.Sh RETURN VALUES
The error codes returned by
.Fn fido_cred_exclude
are defined in
.In fido/err.h .
On success,
.Dv FIDO_OK
is returned.
.Sh SEE ALSO
.Xr fido_cred_new 3 ,
.Xr fido_cred_set_authdata 3 ,
.Xr fido_dev_make_cred 3