sum2.c revision 200462
1/*- 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 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 12 * documentation and/or other materials provided with the distribution. 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. 20 * 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 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 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 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34#ifndef lint 35#if 0 36static char sccsid[] = "@(#)sum2.c 8.1 (Berkeley) 6/6/93"; 37#endif 38#endif /* not lint */ 39#include <sys/cdefs.h> 40__FBSDID("$FreeBSD: head/usr.bin/cksum/sum2.c 200462 2009-12-13 03:14:06Z delphij $"); 41 42#include <sys/types.h> 43 44#include <unistd.h> 45#include <stdint.h> 46 47#include "extern.h" 48 49int 50csum2(int fd, uint32_t *cval, off_t *clen) 51{ 52 uint32_t lcrc; 53 int nr; 54 off_t total; 55 u_char *p; 56 u_char buf[8192]; 57 58 /* 59 * Draft 8 POSIX 1003.2: 60 * 61 * s = sum of all bytes 62 * r = s % 2^16 + (s % 2^32) / 2^16 63 * lcrc = (r % 2^16) + r / 2^16 64 */ 65 lcrc = total = 0; 66 while ((nr = read(fd, buf, sizeof(buf))) > 0) 67 for (total += nr, p = buf; nr--; ++p) 68 lcrc += *p; 69 if (nr < 0) 70 return (1); 71 72 lcrc = (lcrc & 0xffff) + (lcrc >> 16); 73 lcrc = (lcrc & 0xffff) + (lcrc >> 16); 74 75 *cval = lcrc; 76 *clen = total; 77 return (0); 78} 79