RCS_ID_C="$Id: _allocufb.c,v 1.2 1994/03/30 07:39:20 jraja Exp $";
/*
 * _allocufb.c --- get a free ufb
 *
 * Author: jraja <Jarno.Rajahalme@hut.fi>
 *
 * This file is part of the AmiTCP/IP Network Support Library.
 *
 * Copyright © 1994 AmiTCP/IP Group, <amitcp-group@hut.fi>
 *                  Helsinki University of Technology, Finland.
 *                  All rights reserved.
 *
 * Created      : Tue Mar 22 03:57:55 1994 jraja
 * Last modified: Wed Mar 30 10:32:40 1994 jraja
 *
 */

#include <ios1.h>
#include <stdlib.h>
#include <errno.h>

/*
 * Allocate new ufb, which is returned as return value. The corresponding fd
 * is returned via fdp.
 */
struct UFB *
__allocufb(int *fdp)
{
  struct UFB *ufb, *last_ufb;
  int         last_fd = 0;

  /*
   * find first free ufb
   */
  last_ufb = ufb = __ufbs;
  while (ufb != NULL && ufb->ufbflg != 0) {
    last_ufb = ufb;
    last_fd++;
    ufb = last_ufb->ufbnxt;
  }
  /*
   * Check if need to create one
   */
  if (ufb == NULL) {
    if ((ufb = malloc(sizeof(*ufb))) == NULL) {
      errno = ENOMEM;
      return NULL;
    }
    ufb->ufbnxt = NULL;
    ufb->ufbflg = 0;		/* => unused ufb */

    if (last_ufb == NULL)
      __ufbs = ufb;
    else
      last_ufb->ufbnxt = ufb;
    
    *fdp = __nufbs++;
  }
  else
    *fdp = last_fd;
  
  return ufb;
}