Add return error status in the different functions

Add return error status in the different functions

From: Daniel Lezcano <dlezcano@fr.ibm.com>

Add the most known error to the different API to be followed up by the
caller, so we can later show a better message to the user when something
goes wrong. The error catching is coarse grain right now but will be improved,
step by step.

Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>