mem2.c revision 75730 
1/*	$NetBSD: mem2.c,v 1.3 1995/10/02 17:27:11 jpo Exp $	*/
2
3/*
4 * Copyright (c) 1994, 1995 Jochen Pohl
5 * All Rights Reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 *    must display the following acknowledgement:
17 *      This product includes software developed by Jochen Pohl for
18 *	The NetBSD Project.
19 * 4. The name of the author may not be used to endorse or promote products
20 *    derived from this software without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 */
33
34#ifndef lint
35static char rcsid[] = "$FreeBSD: head/usr.bin/xlint/lint2/mem2.c 75730 2001-04-20 09:33:57Z asmodai $";
36#endif
37
38#include <sys/param.h>
39#include <sys/types.h>
40#include <sys/mman.h>
41#include <unistd.h>
42#include <string.h>
43#include <err.h>
44
45#include "lint2.h"
46
47/* length of new allocated memory blocks */
48static size_t	mblklen;
49
50/* offset of next free byte in mbuf */
51static size_t	nxtfree;
52
53/* current buffer to server memory requests from */
54static void	*mbuf;
55
56void
57initmem()
58{
59	int	pgsz;
60
61	pgsz = getpagesize();
62	mblklen = ((MBLKSIZ + pgsz - 1) / pgsz) * pgsz;
63
64	nxtfree = mblklen;
65}
66
67/*
68 * Allocate memory in large chunks to avoid space and time overhead of
69 * malloc(). This is possible because memory allocated by xalloc()
70 * need never to be freed.
71 */
72void *
73xalloc(sz)
74	size_t	sz;
75{
76	void	*ptr;
77	int	prot, flags;
78
79	sz = ALIGN(sz);
80	if (nxtfree + sz > mblklen) {
81		/* use mmap() instead of malloc() to avoid malloc overhead. */
82		prot = PROT_READ | PROT_WRITE;
83		flags = MAP_ANON | MAP_PRIVATE;
84		mbuf = mmap(NULL, mblklen, prot, flags, -1, (off_t)0);
85		if (mbuf == (void *)MAP_FAILED)
86			err(1, "can't map memory");
87		if (ALIGN((u_long)mbuf) != (u_long)mbuf)
88			errx(1, "mapped address is not aligned");
89		(void)memset(mbuf, 0, mblklen);
90		nxtfree = 0;
91	}
92
93	ptr = (char *)mbuf + nxtfree;
94	nxtfree += sz;
95
96	return (ptr);
97}
98