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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 1991-2001 by Sun Microsystems, Inc.
* All rights reserved.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
/*
* zmalloc - use mmap(2) to allocate memory from /dev/zero.
* zfree - use munmap(2) to unmap (free) memory.
*
* These functions should be better than malloc(3) for large memory allocation.
*/
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <zmalloc.h>
/*
* a utility structure to keep track of the (possibly) multiple mmaps
* that we have done...
*/
struct buffer_map {
struct buffer_map *bm_next;
char *bm_buffer;
int bm_size;
};
static void *bm_empty = (void *) ""; /* special buffer */
static struct buffer_map *bm_list; /* NULL by default */
static struct buffer_map *
insert_bm(char *buf, size_t size)
{
struct buffer_map *bm;
bm = (struct buffer_map *)malloc(sizeof (struct buffer_map));
bm->bm_buffer = buf;
bm->bm_size = size;
bm->bm_next = bm_list;
bm_list = bm;
return (bm_list);
}
static size_t
delete_bm(char *buf)
{
size_t size;
register struct buffer_map *p_curr;
register struct buffer_map *p_prev;
p_prev = NULL;
p_curr = bm_list;
while (p_curr != NULL) {
if (p_curr->bm_buffer == buf) {
if (p_prev == NULL)
bm_list = p_curr->bm_next;
else
p_prev->bm_next = p_curr->bm_next;
size = p_curr->bm_size;
free(p_curr);
return (size);
}
p_prev = p_curr;
p_curr = p_curr->bm_next;
}
return (0);
}
void *
zmalloc(size_t size)
{
int fd;
caddr_t mbuf;
/* XXX - Special case: never allocate 0 bytes, use a special buffer */
if (size == 0)
return ((void *)NULL); /* return (bm_empty); */
if ((fd = open("/dev/zero", O_RDWR)) < 0) {
perror("/dev/zero");
return ((void *) NULL);
}
mbuf = mmap(0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
(void) close(fd);
if (mbuf == (caddr_t)-1) {
perror("zmalloc: mmap");
return ((void *) NULL);
}
(void) insert_bm(mbuf, size);
return ((void *) mbuf);
}
void
zfree(void* mbuf)
{
size_t size;
if (mbuf == bm_empty)
return;
if (mbuf != NULL) {
if (size = delete_bm((caddr_t)mbuf)) {
if (munmap((char *)mbuf, size) < 0)
perror("zfree: munmap");
}
}
}
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