.\"
.\" Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
.\" Written by David Howells (dhowells@redhat.com)
.\"
.\" This program is free software; you can redistribute it and/or
.\" modify it under the terms of the GNU General Public License
.\" as published by the Free Software Foundation; either version
.\" 2 of the License, or (at your option) any later version.
.\"
.TH KEYCTL_GET_PERSISTENT 3 "20 Feb 2014" Linux "Linux Key Management Calls"
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.SH NAME
keyctl_get_persistent \- get the persistent keyring for a user
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.SH SYNOPSIS
.nf
.B #include <keyutils.h>
.sp
.BI "long keyctl_get_persistent(uid_t " uid ", key_serial_t " keyring ");"
.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
.SH DESCRIPTION
.BR keyctl_get_persistent ()
gets the persistent keyring for the specified user ID.  Unlike the session and
user keyrings, this keyring will persist once all login sessions have been
deleted and can thus be used to carry authentication tokens for processes that
run without user interaction, such as programs started by cron.
.P
The persistent keyring will be created by the kernel if it does not yet exist.
Each time this function is called, the persistent keyring will have its
expiration timeout reset to the value in:
.IP
/proc/sys/kernel/keys/persistent_keyring_expiry
.P
(by default three days).  Should the timeout be reached, the persistent keyring
will be removed and everything it pins can then be garbage collected.
.P
If
.I uid
is
.B -1
then the calling process's real user ID will be used.  If
.I uid
is not
.B -1
then error
.B EPERM
will be given if the user ID requested does not match either the caller's real
or effective user IDs or if the calling process does not have
.B SetUid
capability.
.P
If successful, a link to the persistent keyring will be added into
.IR keyring .
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.SH RETURN VALUE
On success
.BR keyctl_get_persistent ()
returns the serial number of the persistent keyring.  On error, the value
.B -1
will be returned and
.I errno
will have been set to an appropriate error.
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.SH ERRORS
.TP
.B EPERM
Not permitted to access the persistent keyring for the requested
.IR uid .
.TP
.B ENOMEM
Insufficient memory to create the persistent keyring or to extend
.IR keyring .
.TP
.B ENOKEY
.I keyring
does not exist.
.TP
.B EKEYEXPIRED
.I keyring
has expired.
.TP
.B EKEYREVOKED
.I keyring
has been revoked.
.TP
.B EDQUOT
The user does not have sufficient quota to extend
.IR keyring .
.TP
.B EACCES
.I keyring
exists, but does not grant
.B write
permission to the calling process.

.\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
.SH LINKING
This is a library function that can be found in
.IR libkeyutils .
When linking,
.B -lkeyutils
should be specified to the linker.
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.SH SEE ALSO
.BR keyctl (1),
.br
.BR add_key (2),
.br
.BR keyctl (2),
.br
.BR request_key (2),
.br
.BR keyctl (3),
.br
.BR persistent-keyring (7),
.br
.BR keyutils (7),
.br
.BR keyrings (7)