server/report_rom: partial ROM label matching

Fixes #1801

repos/os/run/report_rom.run

@@ -28,10 +28,8 @@ install_config {
 			<resource name="RAM" quantum="2M"/>
 			<provides> <service name="ROM"/> <service name="Report"/> </provides>
 			<config>
-				<rom>
+				<policy label_prefix="test-report_rom ->" label_suffix="brightness"
-					<policy label="test-report_rom -> brightness"
+				       report="test-report_rom -> brightness"/>
-					       report="test-report_rom -> brightness"/>
-				</rom>
 			</config>
 		</start>
 		<start name="test-report_rom">

repos/os/src/server/report_rom/main.cc

@@ -25,7 +25,6 @@
 
 namespace Server {
 	using Genode::env;
-	using Genode::Xml_node;
 	struct Main;
 }
 
@@ -37,26 +36,9 @@ struct Server::Main
 	Genode::Sliced_heap sliced_heap = { env()->ram_session(),
 	                                    env()->rm_session() };
 
-	Xml_node _rom_config_node() const
+	Rom::Registry rom_registry = { sliced_heap };
-	{
-		try {
-			return Genode::config()->xml_node().sub_node("rom"); }
-		catch (Xml_node::Nonexistent_sub_node) {
-			PWRN("missing <rom> configuration");
-			return Xml_node("<rom>");
-		}
-	}
 
-	Rom::Registry rom_registry = { sliced_heap, _rom_config_node() };
+	bool verbose = Genode::config()->xml_node().attribute_value("verbose", false);
-
-	bool _verbose_config()
-	{
-		char const *attr = "verbose";
-		return Genode::config()->xml_node().has_attribute(attr)
-		    && Genode::config()->xml_node().attribute(attr).has_value("yes");
-	}
-
-	bool verbose = _verbose_config();
 
 	Report::Root report_root = { ep, sliced_heap, rom_registry, verbose };
 	Rom   ::Root    rom_root = { ep, sliced_heap, rom_registry };

repos/os/src/server/report_rom/rom_registry.h

@@ -16,6 +16,7 @@
 
 /* Genode includes */
 #include <report_rom/rom_registry.h>
+#include <os/session_policy.h>
 
 namespace Rom { struct Registry; }
 
@@ -26,8 +27,6 @@ struct Rom::Registry : Registry_for_reader, Registry_for_writer, Genode::Noncopy
 
 		Genode::Allocator &_md_alloc;
 
-		Xml_node _config;
-
 		Module_list _modules;
 
 		struct Read_write_policy : Module::Read_policy, Module::Write_policy
@@ -115,20 +114,26 @@ struct Rom::Registry : Registry_for_reader, Registry_for_writer, Genode::Noncopy
 		 */
 		Module::Name _report_name(Module::Name const &rom_label) const
 		{
+			using namespace Genode;
+
+			String<Rom::Module::Name::capacity()> report;
+
 			try {
-				for (Xml_node node = _config.sub_node("policy");
+				Session_policy policy(rom_label);
-				     true; node = node.next("policy")) {
+				policy.attribute("report").value(&report);
+				return Rom::Module::Name(report.string());
+			} catch (Session_policy::No_policy_defined) {
+				/* FIXME backwards compatibility, remove at next release */
+				try {
+					Xml_node rom_node = config()->xml_node().sub_node("rom");
+					PWRN("parsing legacy <rom> policies");
 
-					if (!node.has_attribute("label")
+					Session_policy policy(rom_label, rom_node);
-					 || !node.has_attribute("report")
+					policy.attribute("report").value(&report);
-					 || !node.attribute("label").has_value(rom_label.string()))
+					return Rom::Module::Name(report.string());
-					 	continue;
+				} catch (Xml_node::Nonexistent_sub_node)    { /* no <rom> node */ }
-
+				  catch (Session_policy::No_policy_defined) { }
-					char report[Rom::Module::Name::capacity()];
+			}
-					node.attribute("report").value(report, sizeof(report));
-					return Rom::Module::Name(report);
-				}
-			} catch (Xml_node::Nonexistent_sub_node) { }
 
 			PWRN("no valid policy for label \"%s\"", rom_label.string());
 			throw Root::Invalid_args();
@@ -136,9 +141,9 @@ struct Rom::Registry : Registry_for_reader, Registry_for_writer, Genode::Noncopy
 
 	public:
 
-		Registry(Genode::Allocator &md_alloc, Xml_node config)
+		Registry(Genode::Allocator &md_alloc)
 		:
-			_md_alloc(md_alloc), _config(config)
+			_md_alloc(md_alloc)
 		{ }
 
 		Module &lookup(Writer &writer, Module::Name const &name) override