/*      $NetBSD: alloc.c,v 1.10 2007/12/12 22:55:42 lukem Exp $ */

/*
 * Copyright (c) 2002 Marc Espie.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE OPENBSD PROJECT AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OPENBSD
 * PROJECT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * area-based allocation built on malloc/free
 */
#include <sys/cdefs.h>
__RCSID("$NetBSD: alloc.c,v 1.10 2007/12/12 22:55:42 lukem Exp $");

#include "sh.h"

struct link {
        struct link *prev;
        struct link *next;
};

Area *
ainit(Area *ap)
{
        ap->freelist = NULL;
        return ap;
}

void
afreeall(Area *ap)
{
        struct link *l, *l2;

        for (l = ap->freelist; l != NULL; l = l2) {
                l2 = l->next;
                free(l);
        }
        ap->freelist = NULL;
}

#define L2P(l)  ( (void *)(((char *)(l)) + sizeof(struct link)) )
#define P2L(p)  ( (struct link *)(((char *)(p)) - sizeof(struct link)) )

/* coverity[+alloc] */
void *
alloc(size_t size, Area *ap)
{
        struct link *l;

        l = malloc(sizeof(struct link) + size);
        if (l == NULL)
                internal_errorf(1, "unable to allocate memory");
        l->next = ap->freelist;
        l->prev = NULL;
        if (ap->freelist)
                ap->freelist->prev = l;
        ap->freelist = l;

        return L2P(l);
}

/* coverity[+alloc] */
/* coverity[+free : arg-0] */
void *
aresize(void *ptr, size_t size, Area *ap)
{
        struct link *l, *l2, *lprev, *lnext;

        if (ptr == NULL)
                return alloc(size, ap);

        l = P2L(ptr);
        lprev = l->prev;
        lnext = l->next;

        l2 = realloc(l, sizeof(struct link) + size);
        if (l2 == NULL)
                internal_errorf(1, "unable to allocate memory");
        if (lprev)
                lprev->next = l2;
        else
                ap->freelist = l2;
        if (lnext)
                lnext->prev = l2;

        return L2P(l2);
}

/* coverity[+free : arg-0] */
void
afree(void *ptr, Area *ap)
{
        struct link *l;

        if (!ptr)
                return;

        l = P2L(ptr);

        if (l->prev)
                l->prev->next = l->next;
        else
                ap->freelist = l->next;
        if (l->next)
                l->next->prev = l->prev;

        free(l);
}