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/*

 * 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 <atomic.h>

#include <rwlock.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_OPEN = VFS_FIRST,

	VFS_CLOSE,

	VFS_READ,

	VFS_WRITE,

	VFS_TRUNCATE,

	VFS_RENAME,

	VFS_OPENDIR,

	VFS_READDIR,

	VFS_CLOSEDIR,

	VFS_UNLINK,

	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_LAST_CLNT,	/* keep this the last member of this enum */

} vfs_request_clnt_t;

typedef enum {

	VFS_REGISTER = VFS_LAST_CMN,

	VFS_SEEK,

	VFS_LAST_SRV,	/* keep this the last member of this enum */

} vfs_request_srv_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 + 1];

	/** Operations. */

	vfs_op_t ops[VFS_LAST_CLNT - 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;

/*

 * Lookup flags.

 */

/**

 * 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_DESTROY 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_DESTROY	16

typedef struct {

	vfs_triplet_t triplet;

	size_t size;

} 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. */

	unsigned refcnt;	/**< Usage counter. */

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

	size_t size;		/**< Cached size of the 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;

	/** 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. */

/** Holding this rwlock prevents changes in file system namespace. */ 

extern rwlock_t namespace_rwlock;

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, 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 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 *);

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 *);

#endif

/**

 * @}

 */