TPMLIB_GetTPMProperty(3)

💖 TPMLIB_GetTPMProperty(3) — NAME 💖

okay bestie, this is the TPMLIB_GetTPMProperty(3) manual, and it's literally about getting a runtime property of the TPM. iconic little fetch quest, no cap. ✨

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📚 LIBRARY 📚

TPM library (libtpms, -ltpms) 🫶

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✨ SYNOPSIS ✨

#include <libtpms/tpm_library.h>

TPM_RESULT TPMLIB_GetTPMProperty(enum TPMLIB_TPMProperty, int *result);

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💅 DESCRIPTION 💅

The TPMLIB_GetTPMProperty() call is your bestie for retrieving run-time parameters of the TPM — things like the number of authorization sessions it can hold, or the maximum sizes of the permanent state, savestate or volatile state blobs. it's giving "ask the TPM for its stats" energy. 💖

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. lowkey consistent, we love that.

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.

⚠️ version vibe check: different TPM versions may return different values, so the docs say to call this after TPMLIB_ChooseTPMVersion() has chosen the version. periodt.

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 margin).
• TPMPROP_TPM_MAX_VOLATILESTATE_SPACE — the maximum size of the volatile state blob (includes the space safety margin).

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😭 ERRORS 😭

• TPM_SUCCESS — the function completed successfully. slay. 💖
• TPM_FAIL — an undefined property was queried. 💀

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

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🧚 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;
}

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🌈 SEE ALSO 🌈

• TPMLIB_MainInit(3)
• TPMLIB_Terminate(3)
• TPMLIB_Process(3)
• TPMLIB_RegisterCallbacks(3)
• TPMLIB_GetVersion(3)
• TPMLIB_ChooseTPMVersion(3)

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that's the whole page, bestie 🫶 source/version: libtpms, date: 2026-01-02, page: TPMLIB_GetTPMProperty(3). literally iconic. 💅✨