os: new ROM logger component

repos/os/src/app/rom_logger/README

@@ -0,0 +1,5 @@
+The rom_logger component requests a ROM session and writes the content of the
+ROM dataspace to the LOG. It responds to configuration and ROM-module updates.
+
+The name of the ROM module must be specified via the 'rom' attribute of the
+components '<config>' node. For example: '<config rom="pointer"/>'.

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

@@ -0,0 +1,113 @@
+/*
+ * \brief  Write content of ROM module to LOG
+ * \author Norman Feske
+ * \date   2015-09-22
+ */
+
+/*
+ * Copyright (C) 2015 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU General Public License version 2.
+ */
+
+/* Genode includes */
+#include <rom_session/connection.h>
+#include <base/signal.h>
+#include <os/config.h>
+#include <os/attached_rom_dataspace.h>
+#include <util/print_lines.h>
+#include <os/server.h>
+#include <util/volatile_object.h>
+
+namespace Rom_logger { struct Main; }
+
+
+struct Rom_logger::Main
+{
+	Server::Entrypoint &_ep;
+
+	Genode::Lazy_volatile_object<Genode::Attached_rom_dataspace> _rom_ds;
+
+	typedef Genode::String<100> Rom_name;
+
+	/**
+	 * Name of currently requested ROM module
+	 *
+	 * Solely used to detect configuration changes.
+	 */
+	Rom_name _rom_name;
+
+	/**
+	 * Signal handler that is invoked when the configuration or the ROM module
+	 * changes.
+	 */
+	void _handle_update(unsigned);
+
+	Genode::Signal_rpc_member<Main> _update_dispatcher =
+		{ _ep, *this, &Main::_handle_update };
+
+	Main(Server::Entrypoint &ep) : _ep(ep)
+	{
+		Genode::config()->sigh(_update_dispatcher);
+		_handle_update(0);
+	}
+};
+
+
+void Rom_logger::Main::_handle_update(unsigned)
+{
+	using Genode::config;
+
+	config()->reload();
+
+	/*
+	 * Query name of ROM module from config
+	 */
+	Rom_name rom_name;
+	try {
+		rom_name = config()->xml_node().attribute_value("rom", rom_name);
+
+	} catch (...) {
+		PWRN("could not determine ROM name from config");
+		return;
+	}
+
+	/*
+	 * If ROM name changed, reconstruct '_rom_ds'
+	 */
+	if (rom_name != _rom_name) {
+		_rom_ds.construct(rom_name.string());
+		_rom_ds->sigh(_update_dispatcher);
+		_rom_name = rom_name;
+	}
+
+	/*
+	 * Update ROM module and print content to LOG
+	 */
+	if (_rom_ds.is_constructed()) {
+		_rom_ds->update();
+
+		if (_rom_ds->is_valid()) {
+			PLOG("ROM '%s':", _rom_name.string());
+
+			Genode::print_lines<200>(_rom_ds->local_addr<char>(), _rom_ds->size(),
+			                         [&] (char const *line) { PLOG("  %s", line); });
+		} else {
+			PLOG("ROM '%s' is invalid", _rom_name.string());
+		}
+	}
+}
+
+
+namespace Server {
+
+	char const *name() { return "ep"; }
+
+	size_t stack_size() { return 4*1024*sizeof(long); }
+
+	void construct(Entrypoint &ep)
+	{
+		static Rom_logger::Main main(ep);
+	}
+}

repos/os/src/app/rom_logger/target.mk

@@ -0,0 +1,3 @@
+TARGET = rom_logger
+SRC_CC = main.cc
+LIBS   = base config server