Component writing a ROM into a file-system session

Fixes #1917

repos/os/run/rom_to_file.run

@@ -0,0 +1,84 @@
+assert_spec linux
+
+#
+# Build
+#
+
+build { core init drivers/timer
+	server/dynamic_rom
+	app/rom_to_file
+	server/lx_fs
+}
+
+create_boot_directory
+
+#
+# Generate config
+#
+
+install_config {
+<config>
+	<parent-provides>
+		<service name="CAP"/>
+		<service name="LOG"/>
+		<service name="RM"/>
+		<service name="SIGNAL"/>
+		<service name="ROM" />
+		<service name="RAM" />
+		<service name="CPU" />
+		<service name="PD" />
+	</parent-provides>
+	<default-route>
+		<any-service> <any-child/> <parent/> </any-service>
+	</default-route>
+	<start name="timer">
+		<resource name="RAM" quantum="1M"/>
+		<provides><service name="Timer"/></provides>
+	</start>
+	<start name="dynamic_rom">
+		<resource name="RAM" quantum="4M"/>
+		<provides><service name="ROM"/></provides>
+		<config verbose="yes">
+			<rom name="test">
+				<inline description="update"><test />
+				</inline>
+				<sleep milliseconds="1000" />
+				<inline description="finished"/>
+			</rom>
+		</config>
+	</start>
+	<start name="lx_fs">
+		<resource name="RAM" quantum="4M"/>
+		<provides> <service name="File_system" /> </provides>
+		<config>
+			<policy label="rom_to_file" root="/fs_test" writeable="yes" />
+		</config>
+	</start>
+	<start name="rom_to_file">
+		<resource name="RAM" quantum="4M"/>
+		<config rom="test" />
+	</start>
+</config>}
+
+#
+# Boot image
+#
+
+exec mkdir -p bin/fs_test
+
+build_boot_image { core init timer
+	dynamic_rom
+	rom_to_file
+	lx_fs
+	fs_test
+}
+
+append qemu_args " -nographic "
+
+run_genode_until "finished" 10
+
+set output [exec cat bin/fs_test/test]
+
+compare_output_to {<test />}
+
+exec rm -r bin/fs_test

repos/os/src/app/rom_to_file/README

@@ -0,0 +1,10 @@
+The rom_to_file component requests a ROM session and writes the content of the
+ROM dataspace to a File_system. 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
+
+! <config rom="pointer"/>
+
+See run/rom_to_file.run for an example.

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

@@ -0,0 +1,170 @@
+/*
+ * \brief  Write content of ROM module to File_system
+ * \author Johannes Schlatow
+ * \date   2016-03-12
+ */
+
+/*
+ * Copyright (C) 2016 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>
+
+#include <base/heap.h>
+#include <base/allocator_avl.h>
+
+#include <file_system_session/connection.h>
+#include <file_system/util.h>
+
+
+namespace Rom_to_file {
+
+	using namespace Genode;
+
+	struct Main;
+
+	enum  {
+		BLOCK_SIZE   = 512,
+		QUEUE_SIZE   = File_system::Session::TX_QUEUE_SIZE,
+		TX_BUF_SIZE  = BLOCK_SIZE * (QUEUE_SIZE*2 + 1)
+	};
+}
+
+
+struct Rom_to_file::Main
+{
+	Server::Entrypoint &_ep;
+
+	Allocator_avl alloc;
+
+	File_system::Connection _fs;
+
+	Lazy_volatile_object<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);
+
+	Signal_rpc_member<Main> _update_dispatcher =
+		{ _ep, *this, &Main::_handle_update };
+
+	Main(Server::Entrypoint &ep) : _ep(ep), alloc(env()->heap()), _fs(alloc, TX_BUF_SIZE)
+	{
+		config()->sigh(_update_dispatcher);
+		_handle_update(0);
+	}
+};
+
+
+void Rom_to_file::Main::_handle_update(unsigned)
+{
+	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()) {
+			using namespace File_system;
+
+			char dir_path[] = "/";
+			const char *file_name = _rom_name.string();
+
+			try {
+				Dir_handle   dir_handle = ensure_dir(_fs, dir_path);
+				Handle_guard dir_guard(_fs, dir_handle);
+				File_handle handle;
+
+				handle = _fs.file(dir_handle, file_name, File_system::WRITE_ONLY, true);
+
+				_fs.truncate(handle, 0);
+
+				size_t len     = max(strlen(_rom_ds->local_addr<char>()), _rom_ds->size());
+				size_t written = write(_fs, handle, _rom_ds->local_addr<void>(), len, 0);
+
+				if (written < len) {
+					PWRN("%zu of %zu bytes have been written", written, len);
+				}
+
+				_fs.close(handle);
+			} catch (Permission_denied) {
+				PERR("%s%s: permission denied", dir_path, file_name);
+
+			} catch (No_space) {
+				PERR("file system out of space");
+
+			} catch (Out_of_metadata) {
+				PERR("server ran out of memory");
+
+			} catch (Invalid_name) {
+				PERR("%s%s: invalid path", dir_path, file_name);
+
+			} catch (Name_too_long) {
+				PERR("%s%s: name too long", dir_path, file_name);
+
+			} catch (...) {
+				PERR("cannot open file %s%s", dir_path, file_name);
+				throw;
+			}
+		} else {
+			PLOG("ROM '%s' is invalid", _rom_name.string());
+		}
+	}
+}
+
+
+namespace Server {
+
+	char const *name() { return "rom_to_file_ep"; }
+
+	size_t stack_size() { return 4*1024*sizeof(long); }
+
+	void construct(Entrypoint &ep)
+	{
+		static Rom_to_file::Main main(ep);
+	}
+}

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

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+TARGET = rom_to_file
+SRC_CC = main.cc
+LIBS   = base config server