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/*

 *  IMFS Linear File Handlers

 *

 *  This file contains the set of handlers used to process operations on

 *  IMFS linear memory file nodes.  Linear memory files are contiguous

 *  blocks of memory created from a TAR or other filesystem image.

 *  The blocks are nonwriteable and nonresizeable.

 *

 *  COPYRIGHT (c) 1989-1999.

 *  On-Line Applications Research Corporation (OAR).

 *

 *  The license and distribution terms for this file may be

 *  found in the file LICENSE in this distribution or at

 *  http://www.OARcorp.com/rtems/license.html.

 *

 *  linearfile.c,v 1.4 2002/04/08 18:28:59 joel Exp

 */

#if HAVE_CONFIG_H

#include "config.h"

#endif

#include <stdlib.h>

#include <assert.h>

#include <string.h>

#include <errno.h>

#include <rtems.h>

#include <rtems/libio.h>

#include "imfs.h"

#include <rtems/libio_.h>

#include <rtems/seterr.h>

/*

 * linearfile_read

 *

 *  This routine processes the read() system call.

 */

int linearfile_read(

  rtems_libio_t *iop,

  void          *buffer,

  unsigned32     count

)

{

  IMFS_jnode_t   *the_jnode;

  unsigned char  *dest;

  unsigned char  *file_ptr;

  int            file_offset;

  the_jnode = iop->file_info;

  /*

   *  Perform internal consistency checks

   */

  assert( the_jnode );

  if ( !the_jnode )

    rtems_set_errno_and_return_minus_one( EIO );

  assert( the_jnode->type == IMFS_LINEAR_FILE );

  if ( the_jnode->type != IMFS_LINEAR_FILE )

    rtems_set_errno_and_return_minus_one( EIO );

  /*

   *  Error checks on arguments

   */

  dest = (unsigned char *)buffer;

  assert( dest );

  if ( !dest )

    rtems_set_errno_and_return_minus_one( EINVAL );

  /*

   *  Perform a simple memory copy.

   */

  if (count == 0)

     return(0);

  the_jnode = iop->file_info;

  file_ptr    = (unsigned char *)the_jnode->info.linearfile.direct;

  file_offset = (unsigned long)iop->offset;

  if (count > (the_jnode->info.linearfile.size - file_offset))

     count = the_jnode->info.linearfile.size - file_offset;

  memcpy(dest, &file_ptr[file_offset], count);

  return(count);

}

/*

 *  linearfile_lseek

 *

 *  This routine processes the lseek() system call.

 */

int linearfile_lseek(

  rtems_libio_t   *iop,

  off_t            offset,

  int              whence

)

{

  IMFS_jnode_t   *the_jnode;

  the_jnode = iop->file_info;

  if (iop->offset > the_jnode->info.linearfile.size)

    iop->offset = the_jnode->info.linearfile.size;

  return iop->offset;

}