---
name: "Fapi_PcrRead"
section: "3"
platform: "linux"
package: "tpm2-tss"
version: "4.2.0-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/Fapi_PcrRead"
---

# Fapi\_PcrRead(3)

Fapi\_PcrRead

## NAME

Fapi\_PcrRead - Fapi\_PcrRead

## SYNOPSIS

### Functions

TSS2\_RC **Fapi\_PcrRead** (**FAPI\_CONTEXT** \*context, uint32\_t pcrIndex, uint8\_t \*\*pcrValue, size\_t \*pcrValueSize, char \*\*pcrLog)\
 TSS2\_RC **Fapi\_PcrRead\_Async** (**FAPI\_CONTEXT** \*context, uint32\_t pcrIndex)\
 TSS2\_RC **Fapi\_PcrRead\_Finish** (**FAPI\_CONTEXT** \*context, uint8\_t \*\*pcrValue, size\_t \*pcrValueSize, char \*\*pcrLog)\

## Detailed Description

FAPI functions to invoke PcrRead either as one-call or in an asynchronous manner.

## Function Documentation

### TSS2\_RC Fapi\_PcrRead (FAPI\_CONTEXT \* context, uint32\_t pcrIndex, uint8\_t \*\* pcrValue, size\_t \* pcrValueSize, char \*\* pcrLog)

One-Call function for Fapi\_PcrRead

Reads from a given PCR and returns the value and the event log.

**Parameters**

*context* The **FAPI\_CONTEXT** \
 *pcrIndex* The index of the PCR to read \
 *pcrValue* The value of the PCR. May be NULL \
 *pcrValueSize* The size of value in bytes. May be NULL \
 *pcrLog* The PCR log. May be NULL

**Return values**

*TSS2\_RC\_SUCCESS* if the function call was a success. \
 *TSS2\_FAPI\_RC\_BAD\_REFERENCE* if context, pcrValue or pcrValueSize is NULL. \
 *TSS2\_FAPI\_RC\_BAD\_CONTEXT* if context corruption is detected. \
 *TSS2\_FAPI\_RC\_BAD\_VALUE* if pcrIndex is invalid. \
 *TSS2\_FAPI\_RC\_BAD\_SEQUENCE* if the context has an asynchronous operation already pending. \
 *TSS2\_FAPI\_RC\_IO\_ERROR* if the data cannot be saved. \
 *TSS2\_FAPI\_RC\_MEMORY* if the FAPI cannot allocate enough memory for internal operations or return parameters. \
 *TSS2\_FAPI\_RC\_NO\_TPM* if FAPI was initialized in no-TPM-mode via its config file. \
 *TSS2\_FAPI\_RC\_TRY\_AGAIN* if an I/O operation is not finished yet and this function needs to be called again. \
 *TSS2\_FAPI\_RC\_AUTHORIZATION\_UNKNOWN* if a required authorization callback is not set. \
 *TSS2\_FAPI\_RC\_AUTHORIZATION\_FAILED* if the authorization attempt fails. \
 *TSS2\_FAPI\_RC\_GENERAL\_FAILURE* if an internal error occurred. \
 *TSS2\_FAPI\_RC\_POLICY\_UNKNOWN* if policy search for a certain policy digest was not successful. \
 *TSS2\_FAPI\_RC\_NO\_CERT* if an error did occur during certificate downloading. \
 *TSS2\_FAPI\_RC\_PATH\_NOT\_FOUND* if a FAPI object path was not found during authorization. \
 *TSS2\_FAPI\_RC\_KEY\_NOT\_FOUND* if a key was not found. \
 *TSS2\_ESYS\_RC\_\** possible error codes of ESAPI.

### TSS2\_RC Fapi\_PcrRead\_Async (FAPI\_CONTEXT \* context, uint32\_t pcrIndex)

Asynchronous function for Fapi\_PcrRead

Reads from a given PCR and returns the value and the event log.

Call Fapi\_PcrRead\_Finish to finish the execution of this command.

**Parameters**

*context* The **FAPI\_CONTEXT** \
 *pcrIndex* The index of the PCR to read

**Return values**

*TSS2\_RC\_SUCCESS* if the function call was a success. \
 *TSS2\_FAPI\_RC\_BAD\_REFERENCE* if context is NULL. \
 *TSS2\_FAPI\_RC\_BAD\_CONTEXT* if context corruption is detected. \
 *TSS2\_FAPI\_RC\_BAD\_VALUE* if pcrIndex is invalid. \
 *TSS2\_FAPI\_RC\_BAD\_SEQUENCE* if the context has an asynchronous operation already pending. \
 *TSS2\_FAPI\_RC\_IO\_ERROR* if the data cannot be saved. \
 *TSS2\_FAPI\_RC\_MEMORY* if the FAPI cannot allocate enough memory for internal operations or return parameters. \
 *TSS2\_FAPI\_RC\_NO\_TPM* if FAPI was initialized in no-TPM-mode via its config file. \
 *TSS2\_ESYS\_RC\_\** possible error codes of ESAPI.

### TSS2\_RC Fapi\_PcrRead\_Finish (FAPI\_CONTEXT \* context, uint8\_t \*\* pcrValue, size\_t \* pcrValueSize, char \*\* pcrLog)

Asynchronous finish function for Fapi\_PcrRead

This function should be called after a previous Fapi\_PcrRead\_Async.

**Parameters**

*context* The **FAPI\_CONTEXT** \
 *pcrValue* The value of the PCR. May be NULL \
 *pcrValueSize* The size of value in bytes. May be NULL \
 *pcrLog* The PCR log. May be NULL

**Return values**

*TSS2\_RC\_SUCCESS* if the function call was a success. \
 *TSS2\_FAPI\_RC\_BAD\_REFERENCE* if context, pcrValue or pcrValueSize is NULL. \
 *TSS2\_FAPI\_RC\_BAD\_CONTEXT* if context corruption is detected. \
 *TSS2\_FAPI\_RC\_BAD\_SEQUENCE* if the context has an asynchronous operation already pending. \
 *TSS2\_FAPI\_RC\_IO\_ERROR* if the data cannot be saved. \
 *TSS2\_FAPI\_RC\_MEMORY* if the FAPI cannot allocate enough memory for internal operations or return parameters. \
 *TSS2\_FAPI\_RC\_TRY\_AGAIN* if the asynchronous operation is not yet complete. Call this function again later. \
 *TSS2\_FAPI\_RC\_BAD\_VALUE* if an invalid value was passed into the function. \
 *TSS2\_ESYS\_RC\_\** possible error codes of ESAPI.

## Author

Generated automatically by Doxygen for tpm2-tss from the source code.