Subversion Repositories or1k

/*
 *  lseek() - POSIX 1003.1b 6.5.3 - Reposition Read/Write File Offset
 *
 *  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.
 *
 *  lseek.c,v 1.11 2002/01/04 18:29:36 joel Exp
 */
 
#if HAVE_CONFIG_H
#include "config.h"
#endif
 
#include <stdio.h>
 
#include <rtems/libio_.h>
#include <rtems/seterr.h>
 
off_t lseek(
  int     fd,
  off_t   offset,
  int     whence
)
{
  rtems_libio_t *iop;
  off_t          old_offset;
  off_t          status;
 
  rtems_libio_check_fd( fd );
  iop = rtems_libio_iop( fd );
  rtems_libio_check_is_open(iop);
 
  /*
   *  Check as many errors as possible before touching iop->offset.
   */
 
  if ( !iop->handlers->lseek_h )
    rtems_set_errno_and_return_minus_one( ENOTSUP );
 
  /*
   *  Now process the lseek().
   */
 
  old_offset = iop->offset;
  switch ( whence ) {
    case SEEK_SET:
      iop->offset = offset;
      break;
 
    case SEEK_CUR:
      iop->offset += offset;
      break;
 
    case SEEK_END:
      iop->offset = iop->size + offset;
      break;
 
    default:
      rtems_set_errno_and_return_minus_one( EINVAL );
  }
 
  /*
   *  At this time, handlers assume iop->offset has the desired
   *  new offset.
   */
 
  status = (*iop->handlers->lseek_h)( iop, offset, whence );
  if ( status == (off_t) -1 )
    iop->offset = old_offset;
 
  /*
   *  So if the operation failed, we have to restore iop->offset.
   */
 
  return status;
}
 
/*
 *  _lseek_r
 *
 *  This is the Newlib dependent reentrant version of lseek().
 */
 
#if defined(RTEMS_NEWLIB)
 
#include <reent.h>
 
off_t _lseek_r( 
  struct _reent *ptr,
  int            fd,
  off_t          offset,
  int            whence
)
{
  return lseek( fd, offset, whence );
}
#endif