---
name: "Fapi_NvRead"
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_NvRead"
---

# Fapi\_NvRead(3)

Fapi\_NvRead

## NAME

Fapi\_NvRead - Fapi\_NvRead

## SYNOPSIS

### Functions

TSS2\_RC **Fapi\_NvRead** (**FAPI\_CONTEXT** \*context, char const \*path, uint8\_t \*\*data, size\_t \*size, char \*\*logData)\
 TSS2\_RC **Fapi\_NvRead\_Async** (**FAPI\_CONTEXT** \*context, char const \*path)\
 TSS2\_RC **Fapi\_NvRead\_Finish** (**FAPI\_CONTEXT** \*context, uint8\_t \*\*data, size\_t \*size, char \*\*logData)\

## Detailed Description

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

## Function Documentation

### TSS2\_RC Fapi\_NvRead (FAPI\_CONTEXT \* context, char const \* nvPath, uint8\_t \*\* data, size\_t \* size, char \*\* logData)

One-Call function for Fapi\_NvRead

Reads data from an NV index within the TPM. The FAPI will automatically do the multiple reads if the NV index is larger than the TPM's TPM2\_MAX\_NV\_BUFFER\_SIZE.

**Parameters**

*context* The **FAPI\_CONTEXT** \
 *nvPath* The path of the NV index to read \
 *data* The data that was read from the NV index \
 *size* The size of data in bytes. May be NULL \
 *logData* The log data of the NV index if the index is of type "extend". May be NULL

**Return values**

*TSS2\_RC\_SUCCESS* if the function call was a success. \
 *TSS2\_FAPI\_RC\_BAD\_REFERENCE* if context, nvPath or data is NULL. \
 *TSS2\_FAPI\_RC\_BAD\_CONTEXT* if context corruption is detected. \
 *TSS2\_FAPI\_RC\_BAD\_PATH* if nvPath is not found. \
 *TSS2\_FAPI\_RC\_AUTHORIZATION\_FAILED* if authorization fails. \
 *TSS2\_FAPI\_RC\_AUTHORIZATION\_UNKNOWN* if don't know how to authenticate. \
 *TSS2\_FAPI\_RC\_NV\_NOT\_READABLE* if the NV is not a readable index. \
 *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\_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\_FAPI\_RC\_BAD\_VALUE* if an invalid value was passed into the function. \
 *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\_GENERAL\_FAILURE* if an internal error occurred. \
 *TSS2\_FAPI\_RC\_POLICY\_UNKNOWN* if policy search for a certain policy digest was not successful. \
 *TSS2\_ESYS\_RC\_\** possible error codes of ESAPI. \
 *TSS2\_FAPI\_RC\_NOT\_PROVISIONED* FAPI was not provisioned.

### TSS2\_RC Fapi\_NvRead\_Async (FAPI\_CONTEXT \* context, char const \* nvPath)

Asynchronous function for Fapi\_NvRead

Reads data from an NV index within the TPM. The FAPI will automatically do the multiple reads if the NV index is larger than the TPM's TPM2\_MAX\_NV\_BUFFER\_SIZE.

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

**Parameters**

*context* The **FAPI\_CONTEXT** \
 *nvPath* The path of the NV index to read

**Return values**

*TSS2\_RC\_SUCCESS* if the function call was a success. \
 *TSS2\_FAPI\_RC\_BAD\_REFERENCE* if context or nvPath is NULL. \* \
 *TSS2\_FAPI\_RC\_BAD\_CONTEXT* if context corruption is detected. \
 *TSS2\_FAPI\_RC\_BAD\_PATH* if nvPath is not found. \
 *TSS2\_FAPI\_RC\_AUTHORIZATION\_FAILED* if authorization fails. \
 *TSS2\_FAPI\_RC\_AUTHORIZATION\_UNKNOWN* if don't know how to authenticate. \
 *TSS2\_FAPI\_RC\_NV\_NOT\_READABLE* if the NV is not a readable index. \
 *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\_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\_FAPI\_RC\_BAD\_VALUE* if an invalid value was passed into the function. \
 *TSS2\_FAPI\_RC\_NOT\_PROVISIONED* FAPI was not provisioned.

### TSS2\_RC Fapi\_NvRead\_Finish (FAPI\_CONTEXT \* context, uint8\_t \*\* data, size\_t \* size, char \*\* logData)

Asynchronous finish function for Fapi\_NvRead

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

**Parameters**

*context* The **FAPI\_CONTEXT** \
 *data* The data that was read from the NV index \
 *size* The size of data in bytes. May be NULL \
 *logData* The log data of the NV index if the index is of type "extend". May be NULL

**Return values**

*TSS2\_RC\_SUCCESS* if the function call was a success. \
 *TSS2\_FAPI\_RC\_BAD\_REFERENCE* if context or data 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\_PATH* if a path is used in inappropriate context or contains illegal characters. \
 *TSS2\_FAPI\_RC\_GENERAL\_FAILURE* if an internal error occurred. \
 *TSS2\_FAPI\_RC\_BAD\_VALUE* if an invalid value was passed into the function. \
 *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\_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\_POLICY\_UNKNOWN* if policy search for a certain policy digest was not successful. \
 *TSS2\_ESYS\_RC\_\** possible error codes of ESAPI. \
 *TSS2\_FAPI\_RC\_NOT\_PROVISIONED* FAPI was not provisioned.

## Author

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