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=head1 NAME
TPMLIB_SetState - Set the TPM's volatile, permanent, or save state
TPMLIB_GetState - Get the TPM's volatile, permanent, or save state
=head1 LIBRARY
TPM library (libtpms, -ltpms)
=head1 SYNOPSIS
B<#include <libtpms/tpm_library.h>>
B<TPM_RESULT TPMLIB_SetState(enum TPMLIB_StateType st,
const unsigned char *buffer, uint32_t buflen);>
B<TPM_RESULT TPMLIB_GetState(enum TPMLIB_StateType st,
unsigned char **buffer, uint32_t *buflen);>
=head1 DESCRIPTION
The B<TPMLIB_SetState()> function allows to set either one of the state blobs of
the TPM. The passed state blob is tested for whether it can be accepted and a TPM
error code is returned in case it cannot be accepted. In case of acceptance, the
state blob will be passed to the TPM upon B<TPM_MainInit()>. Setting a state blob
hides a file that may contain the same type of blob and would be read otherwise.
It is required to call this function with a NULL pointer for the buffer parameter
to hide a state blob in a file.
It is only possible to set the state blobs after B<TPMLIB_ChooseTPMVersion()>
has been called. All state blobs are cleared when a different version of TPM is
chosen using B<TPMLIB_ChooseTPMVersion> or when a call to B<TPMLIB_SetState()>
fails because a state blob could not be accepted.
The order in which state blobs are set is important. The first state blob has
to be the one representing the TPM's permanent state. Only after that either
the volatile or save state blobs can be set.
The B<TPMLIB_GetState()> function allows to get the current state of the TPM.
For as long as the TPM has not been started, this function either returns the state
blob previously set with B<TPMLIB_SetState()> or the state is read from a file.
Once the TPM has been start the state of the running TPM is returned.
The B<TPMLIB_STATE_SAVE_STATE> (save state) type of TPM state can be set with this
function. The same state blob will be returned until TPM_Startup(ST_STATE) has been
called, after which an empty blob will be returned. This blob can also only be
read after TPM_SaveState() has been sent to the TPM.
=head1 SEE ALSO
B<TPMLIB_ChooseTPMVersion>(3), B<TPMLIB_MainInit>(3), B<TPMLIB_Terminate>(3)
=cut
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