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/***********************************************************************
 * fs_desc.h
 *
 * File Descriptor structure declaration and operations.
 * Copyright (C) 2002, 2003, 2004, 2005, 2006 Qualcomm, Inc.
 *
 * This file includes functions declarations for file descriptor operations
 ***********************************************************************/

/*===========================================================================

                        EDIT HISTORY FOR MODULE

  This section contains comments describing changes made to the module.
  Notice that changes are listed in reverse chronological order.

  $Header: //depot/asic/MSMSHARED/services/efs/MSM_EFS.01.02/fs_desc.h#3 $ $DateTime: 2006/01/27 14:54:40 $ $Author: davidb $

when          who     what, where, why
--------      ---     ------------------------------------------------------
2006-01-03    dlb     Make initialization explicit.
2005-12-20    dlb     Descriptor table initialization.
2005-08-09    dlb     Add nodev support.
2004-10-15    dlb     Update copyright line.
2004-10-07    dlb     Whitespace cleanup.
2003-06-17    jkl     Clean up code.
2002-08-27    drh     Created by adm.  Added history header.

===========================================================================*/

#ifndef __FS_DESC_H__
#define __FS_DESC_H__

#include "comdef.h"
#include "fs_sys_types.h"
#include "fs_errno.h"
#include "fs_buffer.h"
#include "fs_vnode.h"
#include "fs_inode.h"
#include "fs_mount.h"

/* A single descriptor contains the following information. */

#define FS_DESC_STATE_CLOSED    0       /* This descriptor is closed. */
#define FS_DESC_STATE_FILE      1       /* This descriptor referrs to a
                                           file. */
struct fs_descriptor;

struct desc_ops {
  int (*close) (struct fs_descriptor *file);
  fs_ssize_t (*write) (struct fs_descriptor *file, const void *buf,
      fs_size_t count);
  fs_ssize_t (*read) (struct fs_descriptor *file, void *buf,
      fs_size_t count);
};

struct fs_descriptor {
  int fd;
  int state;
  uint8 desc_type;              /* To indicate if it is a file
                                   or socket (to be implemented later ) */
  int mode;                     /* What mode is this opened in. */

  /* XXX: Make this a union for socket support. */
  fs_off_t file_pos;            /* Current file position. */
  struct fs_vnode *vp;

  struct desc_ops *dops;
};

/* Lookup the information concerning a descriptor.  Returns a null pointer
 * if this descriptor is not currently open. */
struct fs_descriptor *fs_desc_lookup (int fd);

/* Allocate a new descriptor in preparation for opening.  Returns NULL if
 * there are no descriptors available. */
struct fs_descriptor *fs_desc_alloc (void);

/* Mark a descriptor as free. */
void fs_desc_free (struct fs_descriptor *file);

/* Scan through all open descriptors, and mark as "nodev" the referenced
 * vnodes.  This will cause all future operations (other than close) to
 * fail with ENODEV.  This is used when forcing an umount of a filesystem. */
void fs_desc_make_nodev (struct fs_mount *mp);

/* Initialize the descriptor table. */
void fs_desc_init (void);

#endif /* End of __FS_DESC_H__ */