/*
 * Copyright (c) 2007 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup fs
 * @{
 */ 

#ifndef VFS_VFS_H_
#define VFS_VFS_H_

#include <ipc/ipc.h>
#include <libadt/list.h>
#include <atomic.h>
#include <sys/types.h>
#include <bool.h>

#define dprintf(...)	printf(__VA_ARGS__)

#define VFS_FIRST	IPC_FIRST_USER_METHOD

#define IPC_METHOD_TO_VFS_OP(m)	((m) - VFS_FIRST)	

typedef enum {
	VFS_REGISTER = VFS_FIRST,
	VFS_MOUNT,
	VFS_UNMOUNT,
	VFS_LOOKUP,
	VFS_OPEN,
	VFS_CREATE,
	VFS_CLOSE,
	VFS_READ,
	VFS_WRITE,
	VFS_SEEK,
	VFS_RENAME,
	VFS_UNLINK,
	VFS_LAST,		/* keep this the last member of the enum */
} vfs_request_t;


/**
 * An instance of this structure is associated with a particular FS operation.
 * It tells VFS if the FS supports the operation or maybe if a default one
 * should be used.
 */
typedef enum {
	VFS_OP_NULL = 0,
	VFS_OP_DEFAULT,
	VFS_OP_DEFINED
} vfs_op_t;

#define FS_NAME_MAXLEN	20

/**
 * A structure like this is passed to VFS by each individual FS upon its
 * registration. It assosiates a human-readable identifier with each
 * registered FS. More importantly, through this structure, the FS announces
 * what operations it supports.
 */
typedef struct {
	/** Unique identifier of the fs. */
	char name[FS_NAME_MAXLEN];
	
	/** Operations. */
	vfs_op_t ops[VFS_LAST - VFS_FIRST];
} vfs_info_t;

/**
 * A structure like this will be allocated for each registered file system.
 */
typedef struct {
	link_t fs_link;
	vfs_info_t vfs_info;
	int fs_handle;
	atomic_t phone_futex;	/**< Phone serializing futex. */
	ipcarg_t phone;
} fs_info_t;

/**
 * VFS_PAIR uniquely represents a file system instance.
 */
#define VFS_PAIR	\
	int fs_handle;	\
	int dev_handle;	

/**
 * VFS_TRIPLET uniquely identifies a file system node (e.g. directory, file) but
 * doesn't contain any state. For a stateful structure, see vfs_node_t.
 *
 * @note	fs_handle, dev_handle and index are meant to be returned in one
 *		IPC reply.
 */
#define VFS_TRIPLET	\
	VFS_PAIR;	\
	uint64_t index;

typedef struct {
	VFS_PAIR;
} vfs_pair_t;

typedef struct {
	VFS_TRIPLET;
} vfs_triplet_t;

/**
 * Instances of this type represent an active, in-memory VFS node and any state
 * which may be associated with it.
 */
typedef struct {
	VFS_TRIPLET;		/**< Identity of the node. */
	unsigned refcnt;	/**< Usage counter. */
	link_t nh_link;		/**< Node hash-table link. */
} vfs_node_t;

/**
 * Instances of this type represent an open file. If the file is opened by more
 * than one task, there will be a separate structure allocated for each task.
 */
typedef struct {
	vfs_node_t *node;
	
	/** Number of file handles referencing this file. */
	unsigned refcnt;

	/** Current position in the file. */
	off_t pos;
} vfs_file_t;

extern link_t fs_head;		/**< List of registered file systems. */

extern vfs_triplet_t rootfs;	/**< Root node of the root file system. */

#define MAX_PATH_LEN		(64 * 1024)

#define PLB_SIZE		(2 * MAX_PATH_LEN)

/** Each instance of this type describes one path lookup in progress. */
typedef struct {
	link_t	plb_link;	/**< Active PLB entries list link. */
	unsigned index;		/**< Index of the first character in PLB. */
	size_t len;		/**< Number of characters in this PLB entry. */
} plb_entry_t;

extern atomic_t plb_futex;	/**< Futex protecting plb and plb_head. */
extern uint8_t *plb;		/**< Path Lookup Buffer */
extern link_t plb_head;		/**< List of active PLB entries. */

extern atomic_t unlink_futex;	/**< VFS_{CREATE|OPEN|UNLINK} serialization. */

extern int vfs_grab_phone(int);
extern void vfs_release_phone(int);

extern int fs_name_to_handle(char *, bool);

extern int vfs_lookup_internal(char *, size_t, vfs_triplet_t *, vfs_pair_t *);

extern bool vfs_nodes_init(void);
extern vfs_node_t *vfs_node_get(vfs_triplet_t *);
extern void vfs_node_put(vfs_node_t *);

#define MAX_OPEN_FILES	128

extern bool vfs_files_init(void);
extern vfs_file_t *vfs_file_get(int);
extern int vfs_fd_alloc(void);
extern void vfs_fd_free(int);

extern void vfs_file_addref(vfs_file_t *);
extern void vfs_file_delref(vfs_file_t *);

extern void vfs_node_addref(vfs_node_t *);
extern void vfs_node_delref(vfs_node_t *);

extern void vfs_register(ipc_callid_t, ipc_call_t *);
extern void vfs_mount(ipc_callid_t, ipc_call_t *);
extern void vfs_open(ipc_callid_t, ipc_call_t *);

#endif

/**
 * @}
 */