=head1 NAME

TPMLIB_GetTPMProperty    - Get a runtime property of the TPM
 
=head1 LIBRARY

TPM library (libtpms, -ltpms)

=head1 SYNOPSIS

B<#include <libtpms/tpm_library.h>>

B<TPM_RESULT TPMLIB_GetTPMProperty(enum TPMLIB_TPMProperty, int *result);>

=head1 DESCRIPTION

The B<TPMLIB_GetTPMProperty()> call is used to retrieve run-time parameters
of the TPM such as the number of authorization sessions it can hold or
the maximum sizes of the permanent state, savestate or volatile state blobs.

This function can be called before or after the TPM has been created.
The current implementation of libtpms will return the same value before
and after the TPM was started.

With the introduction of the function B<TPMLIB_ChooseTPMVersion()>,
the call to this function should be executed after the TPM version
has been chosen. The reason is that different TPM versions may return
different values.

The following properties have been defined:

=over 4

=item B<TPMPROP_TPM_RSA_KEY_LENGTH_MAX>

The maximum size of an RSA key.

=item B<TPMPROP_TPM_BUFFER_MAX>

The maximum sizes of the TPM command and result buffers.

=item B<TPMPROP_TPM_KEY_HANDLES>

The number of key slots.

=item B<TPMPROP_TPM_OWNER_EVICT_KEY_HANDLES>

The number of owner-evict keys.

=item B<TPMPROP_TPM_MIN_AUTH_SESSIONS>

The number of authorization sessions.

=item B<TPMPROP_TPM_MIN_TRANS_SESSIONS>

The number of transport sessions.

=item B<TPMPROP_TPM_MIN_DAA_SESSIONS>

The number of DAA sessions.

=item B<TPMPROP_TPM_MIN_SESSION_LIST>

The size of the session list.

=item B<TPMPROP_TPM_MIN_COUNTERS>

The number of monotonic counters.

=item B<TPMPROP_TPM_NUM_FAMILY_TABLE_ENTRY_MIN>

The number of family entries.

=item B<TPMPROP_TPM_NUM_DELEGATE_TABLE_ENTRY_MIN>

The number of delegate entries.

=item B<TPMPROP_TPM_SPACE_SAFETY_MARGIN>

The space saftey margin used for the worst-case sizes of the savestate and
volatile state blobs. This safety marging is not used for the size of the
permanent data blob.

=item B<TPMPROP_TPM_MAX_NV_SPACE>

The maximum size of the permanent data blob.

=item B<TPMPROP_TPM_MAX_SAVESTATE_SPACE>

The maximum size of the savestate blob (includes the space safety margin).

=item B<TPMPROP_TPM_MAX_VOLATILESTATE_SPACE>

The maximum size of the volatile state blob (includes the space saferty
margin).

=back

=head1 ERRORS

=over 4

=item B<TPM_SUCCESS>

The function completed sucessfully.

=item B<TPM_FAIL>

An undefined property was queried.

=back

For a complete list of TPM error codes please consult the include file
B<libtpms/tpm_error.h>

=head1 EXAMPLE

 #include <stdio.h>

 #include <libtpms/tpm_library.h>
 #include <libtpms/tpm_error.h>

 int main(void) {
     TPM_RESULT res;
     int result;
     int rc = 0;

     if (TPMLIB_MainInit() != TPM_SUCCESS) {
         fprintf(stderr, "Could not start the TPM.\n");
         return 1;
     }

     if (TPMLIB_GetTPMProperty(TPMPROP_TPM_RSA_KEY_LENGTH_MAX, &result)
         != TPM_SUCCESS) {
         fprintf(stderr, "Could not read the max. size of RSA keys.\n");
         goto err_exit;
     }

     fprintf(stdout, "Max. size of RSA keys: %d\n", result);

 err_exit:
     TPMLIB_Terminate();

     return 0;
 }

=head1 SEE ALSO

B<TPMLIB_MainInit>(3), B<TPMLIB_Terminate>(3),
B<TPMLIB_Process>(3), B<TPMLIB_RegisterCallbacks>(3), B<TPMLIB_GetVersion>(3),
B<TPMLIB_ChooseTPMVersion>(3)

=cut
