api: disallow virDomainAgentSetResponseTimeout() on read-only connections

This function changes the amount of time that libvirt waits for a
response from the guest agent for all guest agent commands. Since this
is a configuration change, it should not be allowed on read-only
connections.
Signed-off-by: NJonathon Jongsma <jjongsma@redhat.com>
Reviewed-by: NDaniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>

src/libvirt-domain.c

@@ -12576,6 +12576,8 @@ virDomainAgentSetResponseTimeout(virDomainPtr domain,
     virCheckDomainReturn(domain, -1);
     conn = domain->conn;
 
+    virCheckReadOnlyGoto(conn->flags, error);
+
     if (conn->driver->domainAgentSetResponseTimeout) {
         if (conn->driver->domainAgentSetResponseTimeout(domain, timeout, flags) < 0)
             goto error;