base/child.h: remove Nonexistent_id_space exception

This exception got introduced as a mere convenience for implementers of
'Child_policy' but required a special case in the base library.
Following the goal of eliminating exceptions from the base system,
this patch removes it by making a server_id_space mandatory.

Issue #5245

repos/base/include/base/child.h

@@ -162,14 +162,10 @@ struct Genode::Child_policy
 	 */
 	virtual void init(Pd_session &, Capability<Pd_session>) { }
 
-	class Nonexistent_id_space : Exception { };
-
 	/**
 	 * ID space for sessions provided by the child
-	 *
-	 * \throw Nonexistent_id_space
 	 */
-	virtual Id_space<Parent::Server> &server_id_space() { throw Nonexistent_id_space(); }
+	virtual Id_space<Parent::Server> &server_id_space() = 0;
 
 	/**
 	 * Notification hook invoked each time a session state is modified

repos/base/src/core/main.cc

@@ -121,6 +121,8 @@ class Core_child : public Child_policy
 		Cap_quota const _cap_quota;
 		Ram_quota const _ram_quota;
 
+		Id_space<Parent::Server> _server_ids { };
+
 		Child _child;
 
 	public:
@@ -183,6 +185,8 @@ class Core_child : public Child_policy
 		Pd_session_capability ref_pd_cap() const override { return _core_pd_cap; }
 
 		size_t session_alloc_batch_size() const override { return 128; }
+
+		Id_space<Parent::Server> &server_id_space() override { return _server_ids; }
 };
 
 

repos/base/src/lib/base/child.cc

@@ -506,7 +506,6 @@ void Child::session_closed(Session_state &session)
 
 void Child::session_response(Server::Id id, Session_response response)
 {
-	try {
 	_policy.server_id_space().apply<Session_state>(id, [&] (Session_state &session) {
 
 		switch (response) {
@@ -591,14 +590,11 @@ void Child::session_response(Server::Id id, Session_response response)
 	[&] /* missing ID */ {
 		warning("unexpected session response for unknown session");
 	});
-	}
-	catch (Child_policy::Nonexistent_id_space) { }
 }
 
 
 void Child::deliver_session_cap(Server::Id id, Session_capability cap)
 {
-	try {
 	_policy.server_id_space().apply<Session_state>(id, [&] (Session_state &session) {
 
 		/* ignore responses after 'close_all_sessions' of the client */
@@ -631,8 +627,6 @@ void Child::deliver_session_cap(Server::Id id, Session_capability cap)
 			session.ready_callback->session_ready(session);
 	},
 	[&] /* missing ID */ { });
-	}
-	catch (Child_policy::Nonexistent_id_space) { }
 }
 
 
@@ -866,11 +860,8 @@ void Child::close_all_sessions()
 	 * with the server. So the added complexity of reverting the session quotas
 	 * would be to no benefit.
 	 */
-	try {
 	auto lambda = [&] (Session_state &s) { _revert_quota_and_destroy(s); };
 	while (_policy.server_id_space().apply_any<Session_state>(lambda));
-	}
-	catch (Child_policy::Nonexistent_id_space) { }
 
 	/*
 	 * Issue close requests to the providers of the environment sessions,

repos/base/src/test/rm_fault/main.cc

@@ -174,6 +174,7 @@ class Test_child_policy : public Child_policy
 
 		Env                            &_env;
 		Parent_services                &_parent_services;
+		Id_space<Parent::Server>        _server_ids { };
 		Signal_context_capability const _fault_handler_sigh;
 		Signal_context_capability const _fault_handler_stack_sigh;
 
@@ -239,6 +240,8 @@ class Test_child_policy : public Child_policy
 			               .label   = label,
 			               .diag    = diag };
 		}
+
+		Id_space<Parent::Server> &server_id_space() override { return _server_ids; }
 };
 
 

repos/libports/src/lib/libc/fork.cc

@@ -428,6 +428,8 @@ struct Libc::Forked_child : Child_policy, Child_ready
 	Local_clone_service _local_clone_service;
 	Local_rom_service   _config_rom_service;
 
+	Id_space<Parent::Server> _server_ids { };
+
 	pid_t pid() const { return _pid; }
 
 	bool running() const { return _state == State::RUNNING; }
@@ -539,6 +541,8 @@ struct Libc::Forked_child : Child_policy, Child_ready
 		Signal_transmitter(_exit_handler).submit();
 	}
 
+	Id_space<Parent::Server> &server_id_space() override { return _server_ids; }
+
 	Child _child;
 
 	Forked_child(Env                   &env,

repos/os/src/app/sequence/main.cc

@@ -70,6 +70,8 @@ struct Sequence::Child : Genode::Child_policy
 
 	Registry<Parent_service> _parent_services { };
 
+	Id_space<Parent::Server> _server_ids { };
+
 	/* queue a child reload from the async Parent interface */
 	Signal_transmitter _exit_transmitter;
 
@@ -205,6 +207,8 @@ struct Sequence::Child : Genode::Child_policy
 		ref_pd().transfer_quota(pd_cap, Cap_quota{_env.pd().avail_caps().value >> 1});
 		ref_pd().transfer_quota(pd_cap, Ram_quota{_env.pd().avail_ram().value >> 1});
 	}
+
+	Id_space<Parent::Server> &server_id_space() override { return _server_ids; }
 };
 
 

repos/os/src/app/shim/main.cc

@@ -57,6 +57,8 @@ class Shim::Main : public Child_policy
 
 		Parent_services _parent_services { };
 
+		Id_space<Parent::Server> _server_ids { };
+
 		Child _child { _env.rm(), _env.ep().rpc_ep(), *this };
 
 		Service &_matching_service(Service::Name const &name)
@@ -125,6 +127,8 @@ class Shim::Main : public Child_policy
 			                                           label.length()),
 			               .diag    = diag };
 		}
+
+		Id_space<Parent::Server> &server_id_space() override { return _server_ids; }
 };
 
 

repos/os/src/test/bomb/main.cc

@@ -37,6 +37,8 @@ class Bomb_child : public Child_policy
 
 		Registry<Registered<Parent_service> > &_parent_services;
 
+		Id_space<Parent::Server> _server_ids { };
+
 		Child_policy_dynamic_rom_file _config_policy { _env.rm(), "config", _env.ep().rpc_ep(), &_env.ram() };
 
 		Child _child { _env.rm(), _env.ep().rpc_ep(), *this };
@@ -108,6 +110,8 @@ class Bomb_child : public Child_policy
 			               .label   = label,
 			               .diag    = diag };
 		}
+
+		Id_space<Parent::Server> &server_id_space() override { return _server_ids; }
 };
 
 

repos/os/src/test/fault_detection/main.cc

@@ -75,6 +75,7 @@ class Test_child : public Genode::Child_policy
 		Parent_service            _pd_service  { _env,  Pd_session::service_name() };
 		Parent_service            _log_service { _env, Log_session::service_name() };
 		Parent_service            _rom_service { _env, Rom_session::service_name() };
+		Id_space<Parent::Server>  _server_ids { };
 		Child                     _child;
 
 	public:
@@ -134,6 +135,8 @@ class Test_child : public Genode::Child_policy
 
 			throw Service_denied();
 		}
+
+		Id_space<Parent::Server> &server_id_space() override { return _server_ids; }
 };
 
 

repos/os/src/test/resource_yield/main.cc

@@ -288,6 +288,8 @@ class Test::Parent
 			Ram_quota   const _ram_quota { 10*1024*1024 };
 			Binary_name const _binary_name { "test-resource_yield" };
 
+			Id_space<Genode::Parent::Server> _server_ids { };
+
 			/*
 			 * Config ROM service
 			 */
@@ -353,6 +355,8 @@ class Test::Parent
 
 				return route(*service_ptr);
 			}
+
+			Id_space<Genode::Parent::Server> &server_id_space() override { return _server_ids; }
 		};
 
 		Policy _policy { *this, _env };