1 /* $NetBSD: sum1.c,v 1.13 2005/02/05 00:13:34 simonb 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
39 static char sccsid[] = "@(#)sum1.c 8.1 (Berkeley) 6/6/93";
40 #else
41 __RCSID("$NetBSD: sum1.c,v 1.13 2005/02/05 00:13:34 simonb Exp $");
42 #endif
43 #endif /* not lint */
44
45 #include <sys/types.h>
46 #include <unistd.h>
47
48 #include "extern.h"
49
50 int
csum1(int fd,u_int32_t * cval,off_t * clen)51 csum1(int fd, u_int32_t *cval, off_t *clen)
52 {
53 off_t total;
54 int nr;
55 u_int thecrc;
56 u_char *p;
57 u_char buf[8192];
58
59 /*
60 * 16-bit checksum, rotating right before each addition;
61 * overflow is discarded.
62 */
63 thecrc = total = 0;
64 while ((nr = read(fd, buf, sizeof(buf))) > 0)
65 for (total += nr, p = buf; nr--; ++p) {
66 if (thecrc & 1)
67 thecrc |= 0x10000;
68 thecrc = ((thecrc >> 1) + *p) & 0xffff;
69 }
70 if (nr < 0)
71 return 1;
72
73 *cval = thecrc;
74 *clen = total;
75 return 0;
76 }
77