genode/repos/os/src/lib/vfs/terminal_file_system.h

/*
 * \brief  Terminal file system
 * \author Christian Prochaska
 * \author Norman Feske
 * \author Christian Helmuth
 * \date   2012-05-23
 */

/*
 * Copyright (C) 2012-2017 Genode Labs GmbH
 *
 * This file is part of the Genode OS framework, which is distributed
 * under the terms of the GNU Affero General Public License version 3.
 */

#ifndef _INCLUDE__VFS__TERMINAL_FILE_SYSTEM_H_
#define _INCLUDE__VFS__TERMINAL_FILE_SYSTEM_H_

#include <terminal_session/connection.h>
#include <vfs/single_file_system.h>
#include <base/signal.h>
#include <base/registry.h>


namespace Vfs { class Terminal_file_system; }


class Vfs::Terminal_file_system : public Single_file_system
{
	private:

		typedef Genode::String<64> Label;
		Label _label;

		Genode::Env         &_env;
		Io_response_handler &_io_handler;

		Terminal::Connection _terminal { _env, _label.string() };

		typedef Genode::Registered<Vfs_handle>      Registered_handle;
		typedef Genode::Registry<Registered_handle> Handle_registry;

		struct Post_signal_hook : Genode::Entrypoint::Post_signal_hook
		{
			Genode::Entrypoint  &_ep;
			Io_response_handler &_io_handler;
			Vfs_handle::Context *_context = nullptr;

			Post_signal_hook(Genode::Entrypoint &ep,
			                 Io_response_handler &io_handler)
			: _ep(ep), _io_handler(io_handler) { }

			void arm(Vfs_handle::Context *context)
			{
				_context = context;
				_ep.schedule_post_signal_hook(this);
			}

			void function() override
			{
				/*
				 * XXX The current implementation executes the post signal hook
				 *     for the last armed context only. When changing this,
				 *     beware that the called handle_io_response() may change
				 *     this object in a signal handler.
				 */

				_io_handler.handle_io_response(_context);
				_context = nullptr;
			}

			private:

				/*
				 * Noncopyable
				 */
				Post_signal_hook(Post_signal_hook const &);
				Post_signal_hook &operator = (Post_signal_hook const &);
		};

		Post_signal_hook _post_signal_hook { _env.ep(), _io_handler };

		Handle_registry _handle_registry { };

		Genode::Io_signal_handler<Terminal_file_system> _read_avail_handler {
			_env.ep(), *this, &Terminal_file_system::_handle_read_avail };

		void _handle_read_avail()
		{
			_handle_registry.for_each([this] (Registered_handle &h) {
				_post_signal_hook.arm(h.context);
			});
		}

		Read_result _read(Vfs_handle *, char *dst, file_size count,
		                  file_size &out_count)
		{
			if (_terminal.avail()) {
				out_count = _terminal.read(dst, count);
				return READ_OK;
			} else {
				return READ_QUEUED;
			}
		}

	public:

		Terminal_file_system(Genode::Env &env,
		                     Genode::Allocator&,
		                     Genode::Xml_node config,
		                     Io_response_handler &io_handler)
		:
			Single_file_system(NODE_TYPE_CHAR_DEVICE, name(), config),
			_label(config.attribute_value("label", Label())),
			_env(env), _io_handler(io_handler)
		{
			/* register for read-avail notification */
			_terminal.read_avail_sigh(_read_avail_handler);
		}

		static const char *name()   { return "terminal"; }
		char const *type() override { return "terminal"; }

		Open_result open(char const  *path, unsigned,
		                 Vfs_handle **out_handle,
		                 Allocator   &alloc) override
		{
			if (!_single_file(path))
				return OPEN_ERR_UNACCESSIBLE;

			try {
				*out_handle = new (alloc)
					Registered_handle(_handle_registry, *this, *this, alloc, 0);
				return OPEN_OK;
			}
			catch (Genode::Out_of_ram)  { return OPEN_ERR_OUT_OF_RAM; }
			catch (Genode::Out_of_caps) { return OPEN_ERR_OUT_OF_CAPS; }
		}

		/********************************
		 ** File I/O service interface **
		 ********************************/

		Write_result write(Vfs_handle *, char const *buf, file_size buf_size,
		                   file_size &out_count) override
		{
			out_count = _terminal.write(buf, buf_size);
			return WRITE_OK;
		}

		Read_result complete_read(Vfs_handle *vfs_handle, char *dst, file_size count,
		                          file_size &out_count) override
		{
			return _read(vfs_handle, dst, count, out_count);
		}

		bool read_ready(Vfs_handle *) override
		{
			return _terminal.avail();
		}

		Ftruncate_result ftruncate(Vfs_handle *, file_size) override
		{
			return FTRUNCATE_OK;
		}

		bool check_unblock(Vfs_handle *, bool rd, bool wr, bool) override
		{
			if (rd && (_terminal.avail() > 0))
				return true;

			if (wr)
				return true;

			return false;
		}

		void register_read_ready_sigh(Vfs_handle *,
		                              Signal_context_capability sigh) override
		{
			_terminal.read_avail_sigh(sigh);
		}
};

#endif /* _INCLUDE__VFS__TERMINAL_FILE_SYSTEM_H_ */