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 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)sum1.c 8.1 (Berkeley) 6/6/93 30 * $FreeBSD: src/usr.bin/cksum/sum1.c,v 1.8 2003/03/13 23:32:28 robert Exp $ 31 * $DragonFly: src/usr.bin/cksum/sum1.c,v 1.4 2005/04/10 20:55:38 drhodus Exp $ 32 */ 33 34 #include <sys/types.h> 35 36 #include <unistd.h> 37 #include <stdint.h> 38 39 #include "extern.h" 40 41 int 42 csum1(int fd, uint32_t *cval, off_t *clen) 43 { 44 int nr; 45 u_int lcrc; 46 off_t total; 47 u_char *p; 48 u_char buf[8192]; 49 50 /* 51 * 16-bit checksum, rotating right before each addition; 52 * overflow is discarded. 53 */ 54 lcrc = total = 0; 55 while ((nr = read(fd, buf, sizeof(buf))) > 0) 56 for (total += nr, p = buf; nr--; ++p) { 57 if (lcrc & 1) 58 lcrc |= 0x10000; 59 lcrc = ((lcrc >> 1) + *p) & 0xffff; 60 } 61 if (nr < 0) 62 return (1); 63 64 *cval = lcrc; 65 *clen = total; 66 return (0); 67 } 68