init: respond to binary-name changes

This patch covers the resolution of the ROM route for child binaries
via the generic label-rewriting mechanics. Now, the <binary> node has
become merely sytactic sugar for a route like the following:

<start name="test"/>
  <route>
    <service name="ROM" unscoped_label="test">
      <parent label="test-binary-name"/> </service>
      ...
  </route>
  ...
</start>

A change of the binary name has an effect on the child's ROM route to
the binary and thereby implicitly triggers a child restart due to the
existing re-validation of the routing.

repos/os/include/init/child.h

@@ -478,7 +478,8 @@ class Init::Child : Child_policy, Child_service::Wakeup
 			return start_node.sub_node("binary").attribute_value("name", Name());
 		}
 
-		Binary_name const _binary_name;
+		/* updated on configuration update */
+		Binary_name _binary_name;
 
 		struct Read_quota
 		{
@@ -840,6 +841,13 @@ class Init::Child : Child_policy, Child_service::Wakeup
 						config_update = CONFIG_CHANGED;
 				}
 
+				/*
+				 * Import new binary name. A change may affect the route for
+				 * the binary's ROM session, triggering the restart of the
+				 * child.
+				 */
+				_binary_name = _binary_name_from_xml(start_node, _unique_name);
+
 				/* import new start node */
 				_start_node.construct(_alloc, start_node);
 			}
@@ -924,7 +932,7 @@ class Init::Child : Child_policy, Child_service::Wakeup
 
 		Child_policy::Name name() const override { return _unique_name; }
 
-		Binary_name binary_name() const override { return _binary_name; }
+		Binary_name binary_name() const override { return _unique_name; }
 
 		Ram_session           &ref_ram()           override { return _env.ram(); }
 		Ram_session_capability ref_ram_cap() const override { return _env.ram_session_cap(); }
@@ -1002,6 +1010,19 @@ class Init::Child : Child_policy, Child_service::Wakeup
 				 */
 			}
 
+			/*
+			 * Check for the binary's ROM request
+			 *
+			 * The binary is requested as a ROM with the child's unique
+			 * name ('Child_policy::binary_name' equals 'Child_policy::name').
+			 * If the binary name differs from the child's unique name,
+			 * we resolve the session request with the binary name as label.
+			 * Otherwise the regular routing is applied.
+			 */
+			if (service_name == Rom_session::service_name() &&
+			    label == _unique_name && _unique_name != _binary_name)
+				return resolve_session_request(service_name, _binary_name);
+
 			/* check for "session_requests" ROM request */
 			if (service_name == Rom_session::service_name()
 			 && label.last_element() == Session_requester::rom_name())

repos/os/run/init.run

@@ -235,7 +235,78 @@ append config {
 			<sleep ms="100"/>
 
 
+			<message string="test label rewritiong and binary-name update"/>
+
+			<init_config>
+				<parent-provides>
+					<service name="ROM"/> <service name="RAM"/>
+					<service name="CPU"/> <service name="PD"/>
+					<service name="LOG"/>
+				</parent-provides>
+				<start name="test">
+					<binary name="dummy"/>
+					<resource name="RAM" quantum="1M"/>
+					<config version="binary-name test"/>
+					<route>
+						<any-service> <parent/> </any-service>
+					</route>
+				</start>
+			</init_config>
+			<expect_log string="[init -> test] config 1: binary-name test"/>
+
+			<!-- We change the binary name, but also use the label-rewriting
+			     feature of init to produce the same route as the original
+			     binary. Consequently, init does not need to restart the
+			     child. Instead the original child merely prints a new
+			     config version (count 2). -->
+
+			<init_config>
+				<parent-provides>
+					<service name="ROM"/> <service name="RAM"/>
+					<service name="CPU"/> <service name="PD"/>
+					<service name="LOG"/>
+				</parent-provides>
+				<start name="test">
+					<binary name="renamed_dummy"/>
+					<resource name="RAM" quantum="1M"/>
+					<config version="binary re-routed to same route"/>
+					<route>
+						<service name="ROM" unscoped_label="renamed_dummy">
+							<parent label="dummy"/> </service>
+						<any-service> <parent/> </any-service>
+					</route>
+				</start>
+			</init_config>
+			<expect_log string="[init -> test] config 2: binary re-routed to same route"/>
+
+			<!-- We change the binary name in a way that results in a
+			     different route for the binary ROM request, which requires
+			     restart of the child. The config version printed by the
+			     new child will have a count of 1. -->
+
+			<init_config>
+				<parent-provides>
+					<service name="ROM"/> <service name="RAM"/>
+					<service name="CPU"/> <service name="PD"/>
+					<service name="LOG"/>
+				</parent-provides>
+				<start name="test">
+					<binary name="another_dummy"/>
+					<resource name="RAM" quantum="1M"/>
+					<config version="binary re-routed to other route"/>
+					<route>
+						<service name="ROM" unscoped_label="renamed_dummy">
+							<parent label="dummy"/> </service>
+						<any-service> <parent/> </any-service>
+					</route>
+				</start>
+			</init_config>
+			<expect_log string="[init -> test] config 1: binary re-routed to other route"/>
+			<sleep ms="100"/>
+
+
 			<message string="test RAM preservation"/>
+
 			<init_config>
 				<report init_ram="yes"/>
 				<resource name="RAM" preserve="2M"/>
@@ -286,6 +357,11 @@ append config {
 			<service name="Report"> <child name="report_rom"/> </service>
 			<service name="LOG">    <child name="test-init"/> </service>
 			<service name="Timer">  <child name="timer"/>     </service>
+
+			<!-- alias for the binary as requested by the binary-name update test -->
+			<service name="ROM" label="another_dummy">
+				<parent label="dummy"/> </service>
+
 			<any-service> <parent/> </any-service>
 		</route>
 	</start>