genode/ports/src/noux/vfs_io_channel.h

/*
 * \brief  I/O channel for files opened via virtual directory service
 * \author Norman Feske
 * \date   2011-02-17
 */

/*
 * Copyright (C) 2011-2013 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.
 */

#ifndef _NOUX__VFS_IO_CHANNEL_H_
#define _NOUX__VFS_IO_CHANNEL_H_

/* Noux includes */
#include <io_channel.h>
#include <vfs/dir_file_system.h>

namespace Noux {

	struct Vfs_io_channel : Io_channel, Signal_dispatcher_base
	{
		Vfs::Vfs_handle *_fh;

		Absolute_path _path;
		Absolute_path _leaf_path;

		Signal_receiver &_sig_rec;

		Vfs_io_channel(char const *path, char const *leaf_path,
		               Vfs::Dir_file_system *root_dir, Vfs::Vfs_handle *vfs_handle,
		               Signal_receiver &sig_rec)
		: _fh(vfs_handle), _path(path), _leaf_path(leaf_path),
		  _sig_rec(sig_rec)
		{
			_fh->fs().register_read_ready_sigh(_fh, _sig_rec.manage(this));
		}

		~Vfs_io_channel()
		{
			_sig_rec.dissolve(this);
			destroy(env()->heap(), _fh);
		}

		bool write(Sysio *sysio, size_t &offset) override
		{
			size_t out_count = 0;

			sysio->error.write = _fh->fs().write(_fh, sysio->write_in.chunk,
		                                         sysio->write_in.count, out_count);
		    if (sysio->error.write != Vfs::File_io_service::WRITE_OK)
		    	return false;

			_fh->advance_seek(out_count);

			sysio->write_out.count = out_count;
			offset = out_count;

			return true;
		}

		bool read(Sysio *sysio) override
		{
			size_t count = min(sysio->read_in.count, sizeof(sysio->read_out.chunk));

			size_t out_count = 0;

			sysio->error.read = _fh->fs().read(_fh, sysio->read_out.chunk, count, out_count);

			if (sysio->error.read != Vfs::File_io_service::READ_OK)
				return false;

			sysio->read_out.count = out_count;

			_fh->advance_seek(out_count);

			return true;
		}

		bool fstat(Sysio *sysio) override
		{
			/*
			 * 'sysio.stat_in' is not used in '_fh->ds().stat()',
			 * so no 'sysio' member translation is needed here
			 */
			sysio->error.stat =  _fh->ds().stat(_leaf_path.base(),
			                                    sysio->fstat_out.st);

			return (sysio->error.stat == Vfs::Directory_service::STAT_OK);

		}

		bool ftruncate(Sysio *sysio) override
		{

			sysio->error.ftruncate = _fh->fs().ftruncate(_fh, sysio->ftruncate_in.length);

			return (sysio->error.ftruncate == Vfs::File_io_service::FTRUNCATE_OK);
		}

		bool fcntl(Sysio *sysio) override
		{
			switch (sysio->fcntl_in.cmd) {

			case Sysio::FCNTL_CMD_GET_FILE_STATUS_FLAGS:

				sysio->fcntl_out.result = _fh->status_flags();
				return true;

			default:

				PWRN("invalid fcntl command %d", sysio->fcntl_in.cmd);
				sysio->error.fcntl = Sysio::FCNTL_ERR_CMD_INVALID;
				return false;
			};
		}

		/*
		 * The 'dirent' function for the root directory only (the
		 * 'Dir_file_system::open()' function handles all requests referring
		 * to directories). Hence, '_path' is the absolute path of the
		 * directory to inspect.
		 */
		bool dirent(Sysio *sysio) override
		{
			/*
			 * Return artificial dir entries for "." and ".."
			 */
			unsigned const index = _fh->seek() / sizeof(Sysio::Dirent);
			if (index < 2) {
				sysio->dirent_out.entry.type = Vfs::Directory_service::DIRENT_TYPE_DIRECTORY;
				strncpy(sysio->dirent_out.entry.name,
				        index ? ".." : ".",
				        sizeof(sysio->dirent_out.entry.name));

				sysio->dirent_out.entry.fileno = 1;
				_fh->advance_seek(sizeof(Sysio::Dirent));
				return true;
			}

			/*
			 * Delegate remaining dir-entry request to the actual file system.
			 * Align index range to zero when calling the directory service.
			 */

			if (!_fh->ds().dirent(_path.base(), index - 2,
			                      sysio->dirent_out.entry))
				return false;

			_fh->advance_seek(sizeof(Sysio::Dirent));
			return true;
		}

		/**
		 * Return size of file that the I/O channel refers to
		 *
		 * Note that this function overwrites the 'sysio' argument. Do not
		 * call it prior saving all input arguments from the original sysio
		 * structure.
		 */
		size_t size(Sysio *sysio)
		{
			if (fstat(sysio))
				return sysio->fstat_out.st.size;

			return 0;
		}

		bool ioctl(Sysio *sysio) override
		{
			Vfs::File_system::Ioctl_arg arg = (Vfs::File_system::Ioctl_arg)sysio->ioctl_in.argp;

			sysio->error.ioctl = _fh->fs().ioctl(_fh, sysio->ioctl_in.request, arg, sysio->ioctl_out);

			return (sysio->error.ioctl == Vfs::File_io_service::IOCTL_OK);
		}

		bool lseek(Sysio *sysio) override
		{
			switch (sysio->lseek_in.whence) {
			case Sysio::LSEEK_SET: _fh->seek(sysio->lseek_in.offset); break;
			case Sysio::LSEEK_CUR: _fh->advance_seek(sysio->lseek_in.offset); break;
			case Sysio::LSEEK_END:
				off_t offset = sysio->lseek_in.offset;
				sysio->fstat_in.fd = sysio->lseek_in.fd;
				_fh->seek(size(sysio) + offset);
				break;
			}
			sysio->lseek_out.offset = _fh->seek();
			return true;
		}

		bool check_unblock(bool rd, bool wr, bool ex) const override
		{
			return _fh->fs().check_unblock(_fh, rd, wr, ex);
		}

		bool path(char *path, size_t len) override
		{
			strncpy(path, _path.base(), len);
			path[len - 1] = '\0';

			return true;
		}


		/**************************************
		 ** Signal_dispatcher_base interface **
		 **************************************/

		/**
		 * Called by Noux main loop on the occurrence of new input
		 */
		void dispatch(unsigned) override
		{
			Io_channel::invoke_all_notifiers();
		}
	};
}

#endif /* _NOUX__VFS_IO_CHANNEL_H_ */