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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_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 + 1];

    /** 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. */

    /**

     * 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, 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 *);

extern void vfs_read(ipc_callid_t, ipc_call_t *);

extern void vfs_write(ipc_callid_t, ipc_call_t *);

#endif

/**

 * @}

 */