[unix-history] / gnu / libexec / uucp / libuuconf / alloc.c

/* alloc.c
  Allocate within a memory block.

  Copyright (C) 1992 Ian Lance Taylor

  This file is part of the Taylor UUCP uuconf library.

  This 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.

  This 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 this library; if not, write to the Free Software
  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

  The author of the program may be contacted at ian@airs.com or
  c/o Infinity Development Systems, P.O. Box 520, Waltham, MA 02254.
  */

#include "uucnfi.h"

#if USE_RCS_ID
const char _uuconf_alloc_rcsid[] = "$Id: alloc.c,v 1.1 1993/08/04 19:33:34 jtc Exp $";
#endif

#include "alloc.h"
\f
/* Allocate some memory out of a memory block.  If the memory block is
  NULL, this just calls malloc; this is convenient for a number of
  routines.  If this fails, uuconf_errno will be set, and the calling
  routine may return UUCONF_MALLOC_FAILED | UUCONF_ERROR_ERRNO.  */

pointer
uuconf_malloc (pblock, c)
    pointer pblock;
    size_t c;
{
 struct sblock *q = (struct sblock *) pblock;
 pointer pret;

 if (c == 0)
   return NULL;

 if (q == NULL)
   return malloc (c);

 /* Make sure that c is aligned to a double boundary.  */
 c = ((c + sizeof (double) - 1) / sizeof (double)) * sizeof (double);

 while (q->ifree + c > CALLOC_SIZE)
   {
     if (q->qnext != NULL)
       q = q->qnext;
     else
       {
         if (c > CALLOC_SIZE)
           q->qnext = (struct sblock *) malloc (sizeof (struct sblock)
                                                + c - CALLOC_SIZE);
         else
           q->qnext = (struct sblock *) malloc (sizeof (struct sblock));
         if (q->qnext == NULL)
           return NULL;
         q = q->qnext;
         q->qnext = NULL;
         q->ifree = 0;
         q->qadded = NULL;
         break;
       }
   }

 pret = q->u.ab + q->ifree;
 q->ifree += c;
 q->plast = pret;

 return pret;
}