workbench/network/stacks/AROSTCP/netlib/_allocufb.c

   1 /* $Id$
   2  *
   3  *      _allocufb.c - get a free ufb (SAS/C)
   4  *
   5  *      Copyright © 1994 AmiTCP/IP Group,
   6  *                       Network Solutions Development Inc.
   7  *                       All rights reserved.
   8  */
   9
  10 #include <ios1.h>
  11 #include <stdlib.h>
  12 #include <errno.h>
  13
  14 /*
  15  * Allocate new ufb, which is returned as return value. The corresponding fd
  16  * is returned via fdp.
  17  */
  18 struct UFB *
  19 __allocufb(int *fdp)
  20 {
  21   struct UFB *ufb, *last_ufb;
  22   int         last_fd = 0;
  23
  24   /*
  25    * find first free ufb
  26    */
  27   last_ufb = ufb = __ufbs;
  28   while (ufb != NULL && ufb->ufbflg != 0) {
  29     last_ufb = ufb;
  30     last_fd++;
  31     ufb = last_ufb->ufbnxt;
  32   }
  33   /*
  34    * Check if need to create one
  35    */
  36   if (ufb == NULL) {
  37     if ((ufb = malloc(sizeof(*ufb))) == NULL) {
  38       errno = ENOMEM;
  39       return NULL;
  40     }
  41     ufb->ufbnxt = NULL;
  42     ufb->ufbflg = 0;            /* => unused ufb */
  43
  44     if (last_ufb == NULL)
  45       __ufbs = ufb;
  46     else
  47       last_ufb->ufbnxt = ufb;
  48
  49     *fdp = __nufbs++;
  50   }
  51   else
  52     *fdp = last_fd;
  53
  54   return ufb;
  55 }