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set a timeout on a key.
.ip
the id of the key is specified in
.i arg2
(cast to
.ir key_serial_t ).
the timeout value, in seconds from the current time,
is specified in
.i arg3
(cast to
.ir "unsigned int" ).
the timeout is measured against the realtime clock.
.ip
specifying the timeout value as 0 clears any existing timeout on the key.
.ip
the
.i /proc/keys
file displays the remaining time until each key will expire.
(this is the only method of discovering the timeout on a key.)
.ip
the caller must either have the
.i setattr
permission on the key
or hold an instantiation authorization token for the key (see
.br request_key (2)).
.ip
the key and any links to the key will be
automatically garbage collected after the timeout expires.
subsequent attempts to access the key will then fail with the error
.br ekeyexpired .
.ip
this operation cannot be used to set timeouts on revoked, expired,
or negatively instantiated keys.
.ip
the arguments
.ir arg4
and
.ir arg5
are ignored.
.ip
this operation is exposed by
.i libkeyutils
via the function
.br keyctl_set_timeout (3).
.tp
.br keyctl_assume_authority " (since linux 2.6.16)"
assume (or divest) the authority for the calling thread
to instantiate a key.
.ip
the
.i arg2
argument (cast to
.ir key_serial_t )
specifies either a nonzero key id to assume authority,
or the value 0 to divest authority.
.ip
if
.i arg2
is nonzero, then it specifies the id of an uninstantiated key for which
authority is to be assumed.
that key can then be instantiated using one of
.br keyctl_instantiate ,
.br keyctl_instantiate_iov ,
.br keyctl_reject ,
or
.br keyctl_negate .
once the key has been instantiated,
the thread is automatically divested of authority to instantiate the key.
.ip
authority over a key can be assumed only if the calling thread has present
in its keyrings the authorization key that is
associated with the specified key.
(in other words, the
.br keyctl_assume_authority
operation is available only from a
.br request\-key (8)-style
program; see
.br request_key (2)
for an explanation of how this operation is used.)
the caller must have
.i search
permission on the authorization key.
.ip
if the specified key has a matching authorization key,
then the id of that key is returned.
the authorization key can be read
.rb ( keyctl_read )
to obtain the callout information passed to
.br request_key (2).
.ip
if the id given in
.i arg2
is 0, then the currently assumed authority is cleared (divested),
and the value 0 is returned.
.ip
the
.br keyctl_assume_authority
mechanism allows a program such as
.br request\-key (8)
to assume the necessary authority to instantiate a new uninstantiated key