updates the payload of a key if the key type permits it.
The caller must have
permission on a key to be able update it.
specify the data for the new payload.
may be NULL and
may be zero if the key type permits that. The key type may reject the data if
it's in the wrong format or in some other way invalid.
On error, the value
will be returned and errno will have been set to an appropriate error.
The key specified is invalid.
The key specified has expired.
The key specified had been revoked.
The payload data was invalid.
Insufficient memory to store the new payload.
The key quota for this user would be exceeded by increasing the size of the
key to accommodate the new payload.
The key exists, but is not
by the calling process.
The key type does not support the update operation on its keys.
This is a library function that can be found in
should be specified to the linker.