kernel - Fix bogus compiler warning
[dragonfly.git] / usr.bin / cksum / sum2.c
blob893ad00da652cc5d9fe1ff73ea69b8e86ac3aee1
1 /*-
2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
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6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
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13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
33 * @(#)sum2.c 8.1 (Berkeley) 6/6/93
34 * $FreeBSD: src/usr.bin/cksum/sum2.c,v 1.8 2003/03/13 23:32:28 robert Exp $
35 * $DragonFly: src/usr.bin/cksum/sum2.c,v 1.4 2005/04/10 20:55:38 drhodus Exp $
38 #include <sys/types.h>
40 #include <unistd.h>
41 #include <stdint.h>
43 #include "extern.h"
45 int
46 csum2(int fd, uint32_t *cval, off_t *clen)
48 uint32_t lcrc;
49 int nr;
50 off_t total;
51 u_char *p;
52 u_char buf[8192];
55 * Draft 8 POSIX 1003.2:
57 * s = sum of all bytes
58 * r = s % 2^16 + (s % 2^32) / 2^16
59 * lcrc = (r % 2^16) + r / 2^16
61 lcrc = total = 0;
62 while ((nr = read(fd, buf, sizeof(buf))) > 0)
63 for (total += nr, p = buf; nr--; ++p)
64 lcrc += *p;
65 if (nr < 0)
66 return (1);
68 lcrc = (lcrc & 0xffff) + (lcrc >> 16);
69 lcrc = (lcrc & 0xffff) + (lcrc >> 16);
71 *cval = lcrc;
72 *clen = total;
73 return (0);