genode/repos/os/include/vfs/single_file_system.h

/*
 * \brief  File system that hosts a single node
 * \author Norman Feske
 * \date   2014-04-07
 */

/*
 * Copyright (C) 2014 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 _INCLUDE__VFS__SINGLE_FILE_SYSTEM_H_
#define _INCLUDE__VFS__SINGLE_FILE_SYSTEM_H_

#include <vfs/file_system.h>
#include <vfs/vfs_handle.h>

namespace Vfs { class Single_file_system; }


class Vfs::Single_file_system : public File_system
{
	public:

		enum Node_type { NODE_TYPE_FILE, NODE_TYPE_CHAR_DEVICE, NODE_TYPE_BLOCK_DEVICE };

	private:

		Node_type const _node_type;

		enum { FILENAME_MAX_LEN = 64 };
		char _filename[FILENAME_MAX_LEN];

		bool _is_root(const char *path)
		{
			return (strcmp(path, "") == 0) || (strcmp(path, "/") == 0);
		}

		bool _is_single_file(const char *path)
		{
			return (strlen(path) == (strlen(_filename) + 1)) &&
			       (strcmp(&path[1], _filename) == 0);
		}

	public:

		Single_file_system(Node_type node_type, char const *type_name, Xml_node config)
		:
			_node_type(node_type)
		{
			strncpy(_filename, type_name, sizeof(_filename));

			try { config.attribute("name").value(_filename, sizeof(_filename)); }
			catch (...) { }
		}


		/*********************************
		 ** Directory-service interface **
		 *********************************/

		Dataspace_capability dataspace(char const *path) override
		{
			return Dataspace_capability();
		}

		void release(char const *path, Dataspace_capability ds_cap) override { }

		Stat_result stat(char const *path, Stat &out) override
		{
			out = { 0, 0, 0, 0, 0, 0 };

			if (_is_root(path)) {
				out.mode = STAT_MODE_DIRECTORY;

			} else if (_is_single_file(path)) {
				switch (_node_type) {
				case NODE_TYPE_FILE:         out.mode = STAT_MODE_FILE;     break;
				case NODE_TYPE_CHAR_DEVICE:  out.mode = STAT_MODE_CHARDEV;  break;
				case NODE_TYPE_BLOCK_DEVICE: out.mode = STAT_MODE_BLOCKDEV; break;
				}
			} else {
				return STAT_ERR_NO_ENTRY;
			}
			return STAT_OK;
		}

		Dirent_result dirent(char const *path, file_offset index, Dirent &out) override
		{
			if (!_is_root(path))
				return DIRENT_ERR_INVALID_PATH;

			if (index == 0) {
				switch (_node_type) {
				case NODE_TYPE_FILE:         out.type = DIRENT_TYPE_FILE;     break;
				case NODE_TYPE_CHAR_DEVICE:  out.type = DIRENT_TYPE_CHARDEV;  break;
				case NODE_TYPE_BLOCK_DEVICE: out.type = DIRENT_TYPE_BLOCKDEV; break;
				}
				strncpy(out.name, _filename, sizeof(out.name));
			} else {
				out.type = DIRENT_TYPE_END;
			}

			return DIRENT_OK;
		}

		file_size num_dirent(char const *path) override
		{
			if (_is_root(path))
				return 1;
			else
				return 0;
		}

		bool is_directory(char const *path) override
		{
			if (_is_root(path))
				return true;

			return false;
		}

		char const *leaf_path(char const *path) override
		{
			return _is_single_file(path) ? path : 0;
		}

		Open_result open(char const *path, unsigned,
		                 Vfs_handle **out_handle) override
		{
			if (!_is_single_file(path))
				return OPEN_ERR_UNACCESSIBLE;

			*out_handle = new (env()->heap()) Vfs_handle(*this, *this, 0);
			return OPEN_OK;
		}

		Unlink_result unlink(char const *) override
		{
			return UNLINK_ERR_NO_PERM;
		}

		Readlink_result readlink(char const *, char *, file_size,
		                         file_size &) override
		{
			return READLINK_ERR_NO_ENTRY;
		}

		Rename_result rename(char const *from, char const *to) override
		{
			if (_is_single_file(from) || _is_single_file(to))
				return RENAME_ERR_NO_PERM;
			return RENAME_ERR_NO_ENTRY;
		}

		Mkdir_result mkdir(char const *, unsigned) override
		{
			return MKDIR_ERR_NO_PERM;
		}

		Symlink_result symlink(char const *, char const *) override
		{
			return SYMLINK_ERR_NO_ENTRY;
		}


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

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

#endif /* _INCLUDE__VFS__SINGLE_FILE_SYSTEM_H_ */