The e_passwords_xxx_password() functions all return void.  But it's possible for keyring and even keyfile operations to fail.  At least keyfile failures generate a warning on the terminal, but keyring operations just swallow the error.

A better solution would be to have all these functions take a GError and return a boolean.  This would be an API break but I think it's worth it.

Specifically, I'm proposing:

    gboolean e_passwords_remember_password(..., GError **error)
    gboolean e_passwords_add_password(..., GError **error)
    gboolean e_passwords_get_password(..., GError **error)
    gboolean e_passwords_forget_password(..., GError **error)
    gboolean e_passwords_forget_passwords(..., GError **error)
    gboolean e_passwords_clear_passwords(..., GError **error)


One place I discovered recently where this would be useful is in load_source_auth_cb() (e-book-auth-util.c).  This logic:

    if (status == E_BOOK_ERROR_AUTHENTICATION_FAILED)
            e_passwords_forget_password (component_name, stripped_uri);

    addressbook_authenticate (book, TRUE, data->source,
                              load_source_auth_cb, closure);

could be better written as:

    if (status != E_BOOK_ERROR_AUTHENTICATION_FAILED ||
        e_passwords_forget_password (component_name, stripped_uri, &error))

            addressbook_authenticate (book, TRUE, data->source,
                                      load_source_auth_cb, closure);

to avoid a potential busy loop in case "forget password" fails.