/usr.bin/xlint/lint2/mem2.c

 1/*	$NetBSD: mem2.c,v 1.6 2002/01/21 19:49:52 tv 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#include <sys/cdefs.h>
35#if defined(__RCSID) && !defined(lint)
36__RCSID("$NetBSD: mem2.c,v 1.6 2002/01/21 19:49:52 tv Exp $");
37#endif
38__FBSDID("$FreeBSD$");
39
40#include <sys/param.h>
41#include <sys/types.h>
42#include <sys/mman.h>
43#include <err.h>
44#include <unistd.h>
45#include <string.h>
46
47#include "lint2.h"
48
49/* length of new allocated memory blocks */
50static size_t	mblklen;
51
52/* offset of next free byte in mbuf */
53static size_t	nxtfree;
54
55/* current buffer to server memory requests from */
56static void	*mbuf;
57
58void
59initmem(void)
60{
61	int	pgsz;
62
63	pgsz = getpagesize();
64	mblklen = ((MBLKSIZ + pgsz - 1) / pgsz) * pgsz;
65
66	nxtfree = mblklen;
67}
68
69/*
70 * Allocate memory in large chunks to avoid space and time overhead of
71 * malloc(). This is possible because memory allocated by xalloc()
72 * need never to be freed.
73 */
74void *
75xalloc(size_t sz)
76{
77	void	*ptr;
78	int	prot, flags;
79
80	/* Align to at least 8 bytes. */
81	sz = (sz + 7) & ~7L;
82	if (nxtfree + sz > mblklen) {
83		/* use mmap() instead of malloc() to avoid malloc overhead. */
84		prot = PROT_READ | PROT_WRITE;
85		flags = MAP_ANON | MAP_PRIVATE;
86		mbuf = mmap(NULL, mblklen, prot, flags, -1, (off_t)0);
87		if (mbuf == (void *)MAP_FAILED)
88			err(1, "can't map memory");
89		(void)memset(mbuf, 0, mblklen);
90		nxtfree = 0;
91	}
92
93	ptr = (char *)mbuf + nxtfree;
94	nxtfree += sz;
95
96	return (ptr);
97}