Update a key
#include <keyutils.h> long keyctl_update(key_serial_t key, const void *payload, size_t plen);
keyctl_update() updates the payload of a key if the key type permits it.
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 invalid.
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.
EKEYEXPIRED
The key specified has expired.
EKEYREVOKED
The key specified had been revoked.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.
EOPNOTSUPP
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.