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: stable/9/usr.bin/xlint/lint2/mem2.c 148723 2005-08-05 09:07:42Z stefanf $");
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 */
50 static size_t mblklen;
51
52 /* offset of next free byte in mbuf */
53 static size_t nxtfree;
54
55 /* current buffer to server memory requests from */
56 static void *mbuf;
57
58 void
initmem(void)59 initmem(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 */
74 void *
xalloc(size_t sz)75 xalloc(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 }
98