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alloc.c revision 1.6 
      1 /*	$NetBSD: alloc.c,v 1.6 2004/07/07 19:20:09 mycroft Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 2002 Marc Espie.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY THE OPENBSD PROJECT AND CONTRIBUTORS
     16  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     17  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     18  * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OPENBSD
     19  * PROJECT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     20  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     21  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     25  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 
     28 /*
     29  * area-based allocation built on malloc/free
     30  */
     31 
     32 #include "sh.h"
     33 
     34 struct link {
     35 	struct link *prev;
     36 	struct link *next;
     37 };
     38 
     39 Area *
     40 ainit(Area *ap)
     41 {
     42 	ap->freelist = NULL;
     43 	return ap;
     44 }
     45 
     46 void
     47 afreeall(Area *ap)
     48 {
     49 	struct link *l, *l2;
     50 
     51 	for (l = ap->freelist; l != NULL; l = l2) {
     52 		l2 = l->next;
     53 		free(l);
     54 	}
     55 	ap->freelist = NULL;
     56 }
     57 
     58 #define L2P(l)	( (void *)(((char *)(l)) + sizeof(struct link)) )
     59 #define P2L(p)	( (struct link *)(((char *)(p)) - sizeof(struct link)) )
     60 
     61 void *
     62 alloc(size_t size, Area *ap)
     63 {
     64 	struct link *l;
     65 
     66 	l = malloc(sizeof(struct link) + size);
     67 	if (l == NULL)
     68 		internal_errorf(1, "unable to allocate memory");
     69 	l->next = ap->freelist;
     70 	l->prev = NULL;
     71 	if (ap->freelist)
     72 		ap->freelist->prev = l;
     73 	ap->freelist = l;
     74 
     75 	return L2P(l);
     76 }
     77 
     78 void *
     79 aresize(void *ptr, size_t size, Area *ap)
     80 {
     81 	struct link *l, *l2, *lprev, *lnext;
     82 
     83 	if (ptr == NULL)
     84 		return alloc(size, ap);
     85 
     86 	l = P2L(ptr);
     87 	lprev = l->prev;
     88 	lnext = l->next;
     89 
     90 	l2 = realloc(l, sizeof(struct link) + size);
     91 	if (l2 == NULL)
     92 		internal_errorf(1, "unable to allocate memory");
     93 	if (lprev)
     94 		lprev->next = l2;
     95 	else
     96 		ap->freelist = l2;
     97 	if (lnext)
     98 		lnext->prev = l2;
     99 
    100 	return L2P(l2);
    101 }
    102 
    103 void
    104 afree(void *ptr, Area *ap)
    105 {
    106 	struct link *l;
    107 
    108 	if (!ptr)
    109 		return;
    110 
    111 	l = P2L(ptr);
    112 
    113 	if (l->prev)
    114 		l->prev->next = l->next;
    115 	else
    116 		ap->freelist = l->next;
    117 	if (l->next)
    118 		l->next->prev = l->prev;
    119 
    120 	free(l);
    121 }
    122