ssh: add exec channel and exit on interactive

This commit implements the ssh exec channel request. It also handles
some shortcommings on the interactive channel like exit and concurrent
session establishments.

Pipes into the channel do not work yet. E.g.:
echo foobar | ssh noux@localhost -p 5555 "cat > /rw/test.txt"

The issue described with FIXME in Ssh::Server::incoming_connection()
could not be reproduced and might have been fixed with the improved
file descriptor handling.

Fixes #3401

repos/gems/src/test/exec_terminal/main.cc

@@ -0,0 +1,161 @@
+/*
+ * \brief  Component starting noux in a sub-init to execute a specific command
+ * \author Sid Hussmann
+ * \date   2019-05-11
+ */
+
+/*
+ * Copyright (C) 2018 Genode Labs GmbH
+ * Copyright (C) 2019 gapfruit AG
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU Affero General Public License version 3.
+ */
+
+/*
+ * Copyright (C) 2019 gapfruit AG
+ */
+
+
+/* Genode includes */
+#include <base/log.h>
+#include <base/component.h>
+#include <base/attached_rom_dataspace.h>
+#include <os/reporter.h>
+
+/* local includes */
+
+namespace Exec_terminal {
+
+	class Main;
+
+	using namespace Genode;
+}
+
+class Exec_terminal::Main
+{
+	private:
+
+		Env&                   _env;
+		Attached_rom_dataspace _exec_terminal_config           { _env, "exec_terminal.config" };
+		Signal_handler<Main>   _exec_terminal_config_handler   { _env.ep(), *this, &Main::_handle_exec_terminal_config };
+		Expanding_reporter     _init_config_reporter           { _env, "config", "config" };
+
+		unsigned int           _version                        { 0 };
+
+		void _handle_exec_terminal_config();
+
+	public:
+
+		Main(Env& env) :
+			_env{env}
+		{
+			_exec_terminal_config.sigh(_exec_terminal_config_handler);
+			_handle_exec_terminal_config();
+		}
+
+		virtual ~Main() = default;
+};
+
+
+void Exec_terminal::Main::_handle_exec_terminal_config()
+{
+	_exec_terminal_config.update();
+
+	const Xml_node cfg = _exec_terminal_config.xml();
+
+	Genode::log(cfg);
+	if (!cfg.has_type("empty")) {
+		if (cfg.has_attribute("exit")) {
+			_init_config_reporter.generate([&] (Xml_generator& xml) {
+				xml.node("empty");
+			});
+		} else {
+
+			_init_config_reporter.generate([&] (Xml_generator& xml) {
+				xml.node("parent-provides",[&] () {
+					xml.node("service",[&] () { xml.attribute("name", "CPU"); });
+					xml.node("service",[&] () { xml.attribute("name", "File_system"); });
+					xml.node("service",[&] () { xml.attribute("name", "LOG"); });
+					xml.node("service",[&] () { xml.attribute("name", "PD"); });
+					xml.node("service",[&] () { xml.attribute("name", "RM"); });
+					xml.node("service",[&] () { xml.attribute("name", "ROM"); });
+					xml.node("service",[&] () { xml.attribute("name", "Report"); });
+					xml.node("service",[&] () { xml.attribute("name", "Terminal"); });
+					xml.node("service",[&] () { xml.attribute("name", "Timer"); });
+				});
+
+				xml.node("start",[&] () {
+					xml.attribute("name", "noux");
+					xml.attribute("caps", "500");
+					xml.attribute("version", ++_version);
+					xml.node("resource",[&] () { xml.attribute("name", "RAM"); xml.attribute("quantum", "64M"); });
+					xml.node("config",[&] () {
+						xml.node("fstab",[&] () {
+							xml.node("tar",[&] () { xml.attribute("name", "bash.tar"); });
+							xml.node("tar",[&] () { xml.attribute("name", "coreutils-minimal.tar"); });
+							xml.node("tar",[&] () { xml.attribute("name", "vim-minimal.tar"); });
+							xml.node("dir",[&] () {
+								xml.attribute("name", "rw");
+								xml.node("fs",[&] () { xml.attribute("label", "rw"); });
+							});
+							xml.node("dir",[&] () {
+								xml.attribute("name", "tmp");
+								xml.node("ram",[&] () { });
+							});
+						});
+						xml.node("start",[&] () {
+							xml.attribute("name", "/bin/bash");
+							xml.node("env",[&] () {
+								xml.attribute("name", "TERM");
+								xml.attribute("value", "screen");
+							});
+							xml.node("env",[&] () {
+								xml.attribute("name", "HOME");
+								xml.attribute("value", "/");
+							});
+							xml.node("env",[&] () {
+								xml.attribute("name", "IGNOREOF");
+								xml.attribute("value", "3");
+							});
+							if (cfg.has_attribute("command")) {
+								Genode::String<128> cmd;
+								cfg.attribute_value("command", &cmd);
+								if (cmd.valid()) {
+									xml.node("arg",[&] () {
+										xml.attribute("value", "-c");
+									});
+									xml.node("arg",[&] () {
+										// FIXME appending " ; true" is done to force bash to fork.
+										// noux will fail otherwise. This invalidates any exit codes.
+										xml.attribute("value", Genode::String<136>(cmd, " ; true"));
+									});
+								}
+							} else {
+								xml.node("env",[&] () {
+									xml.attribute("name", "PS1");
+									xml.attribute("value", "noux@$PWD> ");
+								});
+							}
+						});
+					});
+					xml.node("route",[&] () {
+						xml.node("service",[&] () { xml.attribute("name", "CPU"); xml.node("parent",[&] () {}); });
+						xml.node("service",[&] () { xml.attribute("name", "File_system"); xml.node("parent",[&] () {}); });
+						xml.node("service",[&] () { xml.attribute("name", "LOG"); xml.node("parent",[&] () {}); });
+						xml.node("service",[&] () { xml.attribute("name", "PD"); xml.node("parent",[&] () {}); });
+						xml.node("service",[&] () { xml.attribute("name", "RM"); xml.node("parent",[&] () {}); });
+						xml.node("service",[&] () { xml.attribute("name", "ROM"); xml.node("parent",[&] () {}); });
+						xml.node("service",[&] () { xml.attribute("name", "Terminal"); xml.node("parent",[&] () {}); });
+						xml.node("service",[&] () { xml.attribute("name", "Timer"); xml.node("parent",[&] () {}); });
+					});
+				});
+			});
+		}
+	}
+}
+
+
+void Component::construct(Genode::Env &env) {
+	static Exec_terminal::Main main(env);
+}

repos/gems/src/test/exec_terminal/target.mk

@@ -0,0 +1,3 @@
+TARGET = exec_terminal
+SRC_CC = main.cc
+LIBS  += base