__getdport.c

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/* Copyright (C) 1991, 1992, 1994 Free Software Foundation, Inc.
This file is part of the GNU C Library.

The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.

The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA.  */

#include <hurd.h>

/* This is initialized in dtable.c when that gets linked in.
   If dtable.c is not linked in, it will be zero.  */
file_t (*_hurd_getdport_fn) (int fd);

file_t
__getdport (int fd)
{
  if (_hurd_getdport_fn)
    /* dtable.c has defined the function to fetch a port from the real file
       descriptor table.  */
    return (*_hurd_getdport_fn) (fd);

  /* getdport is the only use of file descriptors,
     so we don't bother allocating a real table.  */

  if (_hurd_init_dtable == NULL)
    /* Never had a descriptor table.  */
    return EBADF;

  if (fd < 0 || fd > _hurd_init_dtablesize ||
      _hurd_init_dtable[fd] == MACH_PORT_NULL)
    {
      errno = EBADF;
      return MACH_PORT_NULL;
    }
  else      
    {
      __mach_port_mod_refs (__mach_task_self (), _hurd_init_dtable[fd],
			    MACH_PORT_RIGHT_SEND, 1);
      return _hurd_init_dtable[fd];
    }
}