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TPMLIB_GetTPMProperty(3)				TPMLIB_GetTPMProperty(3)

NAME
     TPMLIB_GetTPMProperty    - Get a runtime property of the TPM

LIBRARY
     TPM library (libtpms, -ltpms)

SYNOPSIS
     #include <libtpms/tpm_library.h>

     TPM_RESULT TPMLIB_GetTPMProperty(enum TPMLIB_TPMProperty, int *result);

DESCRIPTION
     The 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 af-
     ter the TPM was started.

     With the introduction of the function 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:

     TPMPROP_TPM_RSA_KEY_LENGTH_MAX
	 The maximum size of an RSA key.

     TPMPROP_TPM_BUFFER_MAX
	 The maximum sizes of the TPM command and result buffers.

     TPMPROP_TPM_KEY_HANDLES
	 The number of key slots.

     TPMPROP_TPM_OWNER_EVICT_KEY_HANDLES
	 The number of owner-evict keys.

     TPMPROP_TPM_MIN_AUTH_SESSIONS
	 The number of authorization sessions.

     TPMPROP_TPM_MIN_TRANS_SESSIONS
	 The number of transport sessions.

     TPMPROP_TPM_MIN_DAA_SESSIONS
	 The number of DAA sessions.

     TPMPROP_TPM_MIN_SESSION_LIST
	 The size of the session list.

     TPMPROP_TPM_MIN_COUNTERS
	 The number of monotonic counters.

     TPMPROP_TPM_NUM_FAMILY_TABLE_ENTRY_MIN
	 The number of family entries.

     TPMPROP_TPM_NUM_DELEGATE_TABLE_ENTRY_MIN
	 The number of delegate entries.

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

     TPMPROP_TPM_MAX_NV_SPACE
	 The maximum size of the permanent data blob.

     TPMPROP_TPM_MAX_SAVESTATE_SPACE
	 The maximum size of the savestate blob (includes the space safety mar-
	 gin).

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

ERRORS
     TPM_SUCCESS
	 The function completed successfully.

     TPM_FAIL
	 An undefined property was queried.

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

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;
      }

SEE ALSO
     TPMLIB_MainInit(3), TPMLIB_Terminate(3), TPMLIB_Process(3), TPMLIB_Regis-
     terCallbacks(3), TPMLIB_GetVersion(3), TPMLIB_ChooseTPMVersion(3)

libtpms 			   2026-01-02		TPMLIB_GetTPMProperty(3)

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