1*0Sstevel@tonic-gate /*
2*0Sstevel@tonic-gate * CDDL HEADER START
3*0Sstevel@tonic-gate *
4*0Sstevel@tonic-gate * The contents of this file are subject to the terms of the
5*0Sstevel@tonic-gate * Common Development and Distribution License, Version 1.0 only
6*0Sstevel@tonic-gate * (the "License"). You may not use this file except in compliance
7*0Sstevel@tonic-gate * with the License.
8*0Sstevel@tonic-gate *
9*0Sstevel@tonic-gate * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10*0Sstevel@tonic-gate * or http://www.opensolaris.org/os/licensing.
11*0Sstevel@tonic-gate * See the License for the specific language governing permissions
12*0Sstevel@tonic-gate * and limitations under the License.
13*0Sstevel@tonic-gate *
14*0Sstevel@tonic-gate * When distributing Covered Code, include this CDDL HEADER in each
15*0Sstevel@tonic-gate * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16*0Sstevel@tonic-gate * If applicable, add the following below this CDDL HEADER, with the
17*0Sstevel@tonic-gate * fields enclosed by brackets "[]" replaced with your own identifying
18*0Sstevel@tonic-gate * information: Portions Copyright [yyyy] [name of copyright owner]
19*0Sstevel@tonic-gate *
20*0Sstevel@tonic-gate * CDDL HEADER END
21*0Sstevel@tonic-gate */
22*0Sstevel@tonic-gate /*
23*0Sstevel@tonic-gate * Copyright (c) 1991-2001 by Sun Microsystems, Inc.
24*0Sstevel@tonic-gate * All rights reserved.
25*0Sstevel@tonic-gate */
26*0Sstevel@tonic-gate
27*0Sstevel@tonic-gate #pragma ident "%Z%%M% %I% %E% SMI"
28*0Sstevel@tonic-gate
29*0Sstevel@tonic-gate /*
30*0Sstevel@tonic-gate * zmalloc - use mmap(2) to allocate memory from /dev/zero.
31*0Sstevel@tonic-gate * zfree - use munmap(2) to unmap (free) memory.
32*0Sstevel@tonic-gate *
33*0Sstevel@tonic-gate * These functions should be better than malloc(3) for large memory allocation.
34*0Sstevel@tonic-gate */
35*0Sstevel@tonic-gate
36*0Sstevel@tonic-gate #include <stdio.h>
37*0Sstevel@tonic-gate #include <stdlib.h>
38*0Sstevel@tonic-gate #include <fcntl.h>
39*0Sstevel@tonic-gate #include <unistd.h>
40*0Sstevel@tonic-gate #include <sys/types.h>
41*0Sstevel@tonic-gate #include <sys/mman.h>
42*0Sstevel@tonic-gate #include <sys/stat.h>
43*0Sstevel@tonic-gate
44*0Sstevel@tonic-gate #include <zmalloc.h>
45*0Sstevel@tonic-gate
46*0Sstevel@tonic-gate /*
47*0Sstevel@tonic-gate * a utility structure to keep track of the (possibly) multiple mmaps
48*0Sstevel@tonic-gate * that we have done...
49*0Sstevel@tonic-gate */
50*0Sstevel@tonic-gate struct buffer_map {
51*0Sstevel@tonic-gate struct buffer_map *bm_next;
52*0Sstevel@tonic-gate char *bm_buffer;
53*0Sstevel@tonic-gate int bm_size;
54*0Sstevel@tonic-gate };
55*0Sstevel@tonic-gate
56*0Sstevel@tonic-gate static void *bm_empty = (void *) ""; /* special buffer */
57*0Sstevel@tonic-gate static struct buffer_map *bm_list; /* NULL by default */
58*0Sstevel@tonic-gate
59*0Sstevel@tonic-gate static struct buffer_map *
insert_bm(char * buf,size_t size)60*0Sstevel@tonic-gate insert_bm(char *buf, size_t size)
61*0Sstevel@tonic-gate {
62*0Sstevel@tonic-gate struct buffer_map *bm;
63*0Sstevel@tonic-gate
64*0Sstevel@tonic-gate bm = (struct buffer_map *)malloc(sizeof (struct buffer_map));
65*0Sstevel@tonic-gate bm->bm_buffer = buf;
66*0Sstevel@tonic-gate bm->bm_size = size;
67*0Sstevel@tonic-gate bm->bm_next = bm_list;
68*0Sstevel@tonic-gate
69*0Sstevel@tonic-gate bm_list = bm;
70*0Sstevel@tonic-gate
71*0Sstevel@tonic-gate return (bm_list);
72*0Sstevel@tonic-gate }
73*0Sstevel@tonic-gate
74*0Sstevel@tonic-gate static size_t
delete_bm(char * buf)75*0Sstevel@tonic-gate delete_bm(char *buf)
76*0Sstevel@tonic-gate {
77*0Sstevel@tonic-gate size_t size;
78*0Sstevel@tonic-gate register struct buffer_map *p_curr;
79*0Sstevel@tonic-gate register struct buffer_map *p_prev;
80*0Sstevel@tonic-gate
81*0Sstevel@tonic-gate p_prev = NULL;
82*0Sstevel@tonic-gate p_curr = bm_list;
83*0Sstevel@tonic-gate while (p_curr != NULL) {
84*0Sstevel@tonic-gate if (p_curr->bm_buffer == buf) {
85*0Sstevel@tonic-gate if (p_prev == NULL)
86*0Sstevel@tonic-gate bm_list = p_curr->bm_next;
87*0Sstevel@tonic-gate else
88*0Sstevel@tonic-gate p_prev->bm_next = p_curr->bm_next;
89*0Sstevel@tonic-gate size = p_curr->bm_size;
90*0Sstevel@tonic-gate free(p_curr);
91*0Sstevel@tonic-gate return (size);
92*0Sstevel@tonic-gate }
93*0Sstevel@tonic-gate
94*0Sstevel@tonic-gate p_prev = p_curr;
95*0Sstevel@tonic-gate p_curr = p_curr->bm_next;
96*0Sstevel@tonic-gate }
97*0Sstevel@tonic-gate return (0);
98*0Sstevel@tonic-gate }
99*0Sstevel@tonic-gate
100*0Sstevel@tonic-gate void *
zmalloc(size_t size)101*0Sstevel@tonic-gate zmalloc(size_t size)
102*0Sstevel@tonic-gate {
103*0Sstevel@tonic-gate int fd;
104*0Sstevel@tonic-gate caddr_t mbuf;
105*0Sstevel@tonic-gate
106*0Sstevel@tonic-gate /* XXX - Special case: never allocate 0 bytes, use a special buffer */
107*0Sstevel@tonic-gate if (size == 0)
108*0Sstevel@tonic-gate return ((void *)NULL); /* return (bm_empty); */
109*0Sstevel@tonic-gate
110*0Sstevel@tonic-gate if ((fd = open("/dev/zero", O_RDWR)) < 0) {
111*0Sstevel@tonic-gate perror("/dev/zero");
112*0Sstevel@tonic-gate return ((void *) NULL);
113*0Sstevel@tonic-gate }
114*0Sstevel@tonic-gate
115*0Sstevel@tonic-gate mbuf = mmap(0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
116*0Sstevel@tonic-gate (void) close(fd);
117*0Sstevel@tonic-gate
118*0Sstevel@tonic-gate if (mbuf == (caddr_t)-1) {
119*0Sstevel@tonic-gate perror("zmalloc: mmap");
120*0Sstevel@tonic-gate return ((void *) NULL);
121*0Sstevel@tonic-gate }
122*0Sstevel@tonic-gate
123*0Sstevel@tonic-gate (void) insert_bm(mbuf, size);
124*0Sstevel@tonic-gate
125*0Sstevel@tonic-gate return ((void *) mbuf);
126*0Sstevel@tonic-gate }
127*0Sstevel@tonic-gate
128*0Sstevel@tonic-gate void
zfree(void * mbuf)129*0Sstevel@tonic-gate zfree(void* mbuf)
130*0Sstevel@tonic-gate {
131*0Sstevel@tonic-gate size_t size;
132*0Sstevel@tonic-gate
133*0Sstevel@tonic-gate if (mbuf == bm_empty)
134*0Sstevel@tonic-gate return;
135*0Sstevel@tonic-gate
136*0Sstevel@tonic-gate if (mbuf != NULL) {
137*0Sstevel@tonic-gate if (size = delete_bm((caddr_t)mbuf)) {
138*0Sstevel@tonic-gate if (munmap((char *)mbuf, size) < 0)
139*0Sstevel@tonic-gate perror("zfree: munmap");
140*0Sstevel@tonic-gate }
141*0Sstevel@tonic-gate }
142*0Sstevel@tonic-gate }
143