/*
 * Copyright (c) 2008 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 <futex.h>
#include <rwlock.h>
#include <sys/types.h>
#include <devmap.h>
#include <bool.h>

// FIXME: according to CONFIG_DEBUG
// #define dprintf(...)	printf(__VA_ARGS__)

#define dprintf(...)

#define VFS_FIRST	IPC_FIRST_USER_METHOD

/* Basic types. */
typedef int16_t fs_handle_t;
typedef uint32_t fs_index_t;

typedef enum {
	VFS_READ = VFS_FIRST,
	VFS_WRITE,
	VFS_TRUNCATE,
	VFS_MOUNT,
	VFS_UNMOUNT,
	VFS_LAST_CMN,	/* keep this the last member of this enum */
} vfs_request_cmn_t;

typedef enum {
	VFS_LOOKUP = VFS_LAST_CMN,
	VFS_MOUNTED,
	VFS_DESTROY,
	VFS_LAST_CLNT,	/* keep this the last member of this enum */
} vfs_request_clnt_t;

typedef enum {
	VFS_REGISTER = VFS_LAST_CMN,
	VFS_OPEN,
	VFS_CLOSE,
	VFS_SEEK,
	VFS_MKDIR,
	VFS_UNLINK,
	VFS_RENAME,
	VFS_LAST_SRV,	/* keep this the last member of this enum */
} vfs_request_srv_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.
 */
typedef struct {
	/** Unique identifier of the fs. */
	char name[FS_NAME_MAXLEN + 1];
} 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;
	fs_handle_t fs_handle;
	futex_t phone_futex;	/**< Phone serializing futex. */
	ipcarg_t phone;
} fs_info_t;

/**
 * VFS_PAIR uniquely represents a file system instance.
 */
#define VFS_PAIR		\
	fs_handle_t fs_handle;	\
	dev_handle_t 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;	\
	fs_index_t index;

typedef struct {
	VFS_PAIR;
} vfs_pair_t;

typedef struct {
	VFS_TRIPLET;
} vfs_triplet_t;

/*
 * Lookup flags.
 */
/**
 * No lookup flags used.
 */
#define L_NONE		0
/**
 * Lookup will succeed only if the object is a regular file.  If L_CREATE is
 * specified, an empty file will be created. This flag is mutually exclusive
 * with L_DIRECTORY.
 */
#define L_FILE		1
/**
 * Lookup wil succeed only if the object is a directory. If L_CREATE is
 * specified, an empty directory will be created. This flag is mutually
 * exclusive with L_FILE.
 */
#define L_DIRECTORY	2
/**
 * When used with L_CREATE, L_EXCLUSIVE will cause the lookup to fail if the
 * object already exists. L_EXCLUSIVE is implied when L_DIRECTORY is used.
 */
#define L_EXCLUSIVE	4
/**
 * L_CREATE is used for creating both regular files and directories.
 */
#define L_CREATE	8
/**
 * L_LINK is used for linking to an already existing nodes.
 */
#define L_LINK		16
/**
 * L_UNLINK is used to remove leaves from the file system namespace. This flag
 * cannot be passed directly by the client, but will be set by VFS during
 * VFS_UNLINK.
 */
#define L_UNLINK	32	

typedef enum vfs_node_type {
	VFS_NODE_UNKNOWN,
	VFS_NODE_FILE,
	VFS_NODE_DIRECTORY,
} vfs_node_type_t;

typedef struct {
	vfs_triplet_t triplet;
	vfs_node_type_t type;
	size_t size;
	unsigned lnkcnt;
} vfs_lookup_res_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. */

	/**
	 * Usage counter.  This includes, but is not limited to, all vfs_file_t
	 * structures that reference this node.
	 */
	unsigned refcnt;
	
	/** Number of names this node has in the file system namespace. */
	unsigned lnkcnt;

	link_t nh_link;		/**< Node hash-table link. */

	vfs_node_type_t type;	/**< Partial info about the node type. */

	size_t size;		/**< Cached size if the node is a file. */

	/**
	 * Holding this rwlock prevents modifications of the node's contents.
	 */
	rwlock_t contents_rwlock;
} 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 {
	/** Serializes access to this open file. */
	futex_t lock;

	vfs_node_t *node;
	
	/** Number of file handles referencing this file. */
	unsigned refcnt;

	/** Append on write. */
	bool append;

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

extern futex_t nodes_futex;

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

extern vfs_pair_t rootfs;	/**< 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 futex_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. */

#define MAX_MNTOPTS_LEN		256

/** Holding this rwlock prevents changes in file system namespace. */ 
extern rwlock_t namespace_rwlock;

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

extern fs_handle_t fs_name_to_handle(char *, bool);

extern int vfs_lookup_internal(char *, int, vfs_lookup_res_t *, vfs_pair_t *,
    ...);

extern bool vfs_nodes_init(void);
extern vfs_node_t *vfs_node_get(vfs_lookup_res_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 int 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_process_pending_mount(void);
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 *);
extern void vfs_close(ipc_callid_t, ipc_call_t *);
extern void vfs_read(ipc_callid_t, ipc_call_t *);
extern void vfs_write(ipc_callid_t, ipc_call_t *);
extern void vfs_seek(ipc_callid_t, ipc_call_t *);
extern void vfs_truncate(ipc_callid_t, ipc_call_t *);
extern void vfs_mkdir(ipc_callid_t, ipc_call_t *);
extern void vfs_unlink(ipc_callid_t, ipc_call_t *);
extern void vfs_rename(ipc_callid_t, ipc_call_t *);

#endif

/**
 * @}
 */