keyctl_update - Update a key
long keyctl_update(key_serial_t key, const char *payload,
keyctl_update() updates the payload of a key if the key type permits
The caller must have write permission on a key to be able update it.
payload and plen specify the data for the new payload. payload may be
NULL and plen 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
On success keyctl_update() returns 0. On error, the value -1 will be
returned and errno will have been set to an appropriate error.
ENOKEY The key specified is invalid.
The key specified has expired.
The key specified had been revoked.
EINVAL The payload data was invalid.
ENOMEM Insufficient memory to store the new payload.
EDQUOT The key quota for this user would be exceeded by increasing the
size of the key to accommodate the new payload.
EACCES The key exists, but is not writable 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 libkeyutils. When
linking, -lkeyutils should be specified to the linker.