Annotation of src/usr.bin/cksum/sum1.c, Revision 1.1.1.1
1.1 deraadt 1: /* $NetBSD: sum1.c,v 1.4 1995/03/26 05:15:23 glass 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. All advertising materials mentioning features or use of this software
16: * must display the following acknowledgement:
17: * This product includes software developed by the University of
18: * California, Berkeley and its contributors.
19: * 4. Neither the name of the University nor the names of its contributors
20: * may be used to endorse or promote products derived from this software
21: * without specific prior written permission.
22: *
23: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33: * SUCH DAMAGE.
34: */
35:
36: #ifndef lint
37: #if 0
38: static char sccsid[] = "@(#)sum1.c 8.1 (Berkeley) 6/6/93";
39: #else
40: static char rcsid[] = "$NetBSD: sum1.c,v 1.4 1995/03/26 05:15:23 glass Exp $";
41: #endif
42: #endif /* not lint */
43:
44: #include <sys/types.h>
45: #include <unistd.h>
46:
47: int
48: csum1(fd, cval, clen)
49: register int fd;
50: u_long *cval, *clen;
51: {
52: register u_long total;
53: register int nr;
54: register u_int crc;
55: register u_char *p;
56: u_char buf[8192];
57:
58: /*
59: * 16-bit checksum, rotating right before each addition;
60: * overflow is discarded.
61: */
62: crc = total = 0;
63: while ((nr = read(fd, buf, sizeof(buf))) > 0)
64: for (total += nr, p = buf; nr--; ++p) {
65: if (crc & 1)
66: crc |= 0x10000;
67: crc = ((crc >> 1) + *p) & 0xffff;
68: }
69: if (nr < 0)
70: return(1);
71:
72: *cval = crc;
73: *clen = total;
74: return(0);
75: }