1/*	$NetBSD: sum2.c,v 1.12 2005/01/12 17:04:35 xtraeme Exp $	*/
2
3/*-
4 * Copyright (c) 1991, 1993
5 *	The Regents of the University of California.  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. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#if HAVE_NBTOOL_CONFIG_H
33#include "nbtool_config.h"
34#endif
35
36#include <sys/cdefs.h>
37#if defined(__RCSID) && !defined(lint)
38#if 0
39static char sccsid[] = "@(#)sum2.c	8.1 (Berkeley) 6/6/93";
40#else
41__RCSID("$NetBSD: sum2.c,v 1.12 2005/01/12 17:04:35 xtraeme Exp $");
42#endif
43#endif /* not lint */
44
45#include <sys/types.h>
46#include <unistd.h>
47
48#include "extern.h"
49
50int
51csum2(int fd, u_int32_t *cval, off_t *clen)
52{
53	u_int32_t thecrc;
54	off_t total;
55	int nr;
56	u_char *p;
57	u_char buf[8192];
58
59	/*
60	 * Draft 8 POSIX 1003.2:
61	 *
62	 *      s = sum of all bytes
63	 *      r = s % 2^16 + (s % 2^32) / 2^16
64	 * thecrc = (r % 2^16) + r / 2^16
65	 */
66	thecrc = 0;
67	total = 0;
68	while ((nr = read(fd, buf, sizeof(buf))) > 0)
69		for (total += nr, p = buf; nr--; ++p)
70			thecrc += *p;
71	if (nr < 0)
72		return 1;
73
74	thecrc = (thecrc & 0xffff) + (thecrc >> 16);
75	thecrc = (thecrc & 0xffff) + (thecrc >> 16);
76
77	*cval = thecrc;
78	*clen = total;
79	return 0;
80}
81