1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
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#ifndef lint
33#if 0
34static char sccsid[] = "@(#)sum2.c	8.1 (Berkeley) 6/6/93";
35#endif
36#endif /* not lint */
37#include <sys/cdefs.h>
38__FBSDID("$FreeBSD$");
39
40#include <sys/types.h>
41
42#include <unistd.h>
43#include <stdint.h>
44
45#include "extern.h"
46
47int
48csum2(int fd, uint32_t *cval, off_t *clen)
49{
50	uint32_t lcrc;
51	int nr;
52	off_t total;
53	u_char *p;
54	u_char buf[8192];
55
56	/*
57	 * Draft 8 POSIX 1003.2:
58	 *
59	 *   s = sum of all bytes
60	 *   r = s % 2^16 + (s % 2^32) / 2^16
61	 * lcrc = (r % 2^16) + r / 2^16
62	 */
63	lcrc = total = 0;
64	while ((nr = read(fd, buf, sizeof(buf))) > 0)
65		for (total += nr, p = buf; nr--; ++p)
66			lcrc += *p;
67	if (nr < 0)
68		return (1);
69
70	lcrc = (lcrc & 0xffff) + (lcrc >> 16);
71	lcrc = (lcrc & 0xffff) + (lcrc >> 16);
72
73	*cval = lcrc;
74	*clen = total;
75	return (0);
76}
77