sum1.c revision 200462
11590Srgrimes/*- 21590Srgrimes * Copyright (c) 1991, 1993 31590Srgrimes * The Regents of the University of California. All rights reserved. 41590Srgrimes * 51590Srgrimes * Redistribution and use in source and binary forms, with or without 61590Srgrimes * modification, are permitted provided that the following conditions 71590Srgrimes * are met: 81590Srgrimes * 1. Redistributions of source code must retain the above copyright 91590Srgrimes * notice, this list of conditions and the following disclaimer. 101590Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 111590Srgrimes * notice, this list of conditions and the following disclaimer in the 121590Srgrimes * documentation and/or other materials provided with the distribution. 131590Srgrimes * 3. All advertising materials mentioning features or use of this software 141590Srgrimes * must display the following acknowledgement: 151590Srgrimes * This product includes software developed by the University of 161590Srgrimes * California, Berkeley and its contributors. 171590Srgrimes * 4. Neither the name of the University nor the names of its contributors 181590Srgrimes * may be used to endorse or promote products derived from this software 191590Srgrimes * without specific prior written permission. 201590Srgrimes * 211590Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 221590Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 231590Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 241590Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 251590Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 261590Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 271590Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 281590Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 291590Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 301590Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 311590Srgrimes * SUCH DAMAGE. 321590Srgrimes */ 331590Srgrimes 341590Srgrimes#ifndef lint 3554162Scharnier#if 0 3654162Scharnierstatic char sccsid[] = "@(#)sum1.c 8.1 (Berkeley) 6/6/93"; 3754162Scharnier#endif 381590Srgrimes#endif /* not lint */ 39112212Srobert 4099112Sobrien#include <sys/cdefs.h> 4199112Sobrien__FBSDID("$FreeBSD: head/usr.bin/cksum/sum1.c 200462 2009-12-13 03:14:06Z delphij $"); 421590Srgrimes 431590Srgrimes#include <sys/types.h> 44112212Srobert 451590Srgrimes#include <unistd.h> 46200462Sdelphij#include <stdint.h> 471590Srgrimes 4887212Smarkm#include "extern.h" 4987212Smarkm 501590Srgrimesint 51112212Srobertcsum1(int fd, uint32_t *cval, off_t *clen) 521590Srgrimes{ 5387212Smarkm int nr; 5487212Smarkm u_int lcrc; 55112212Srobert off_t total; 5687212Smarkm u_char *p; 571590Srgrimes u_char buf[8192]; 581590Srgrimes 591590Srgrimes /* 601590Srgrimes * 16-bit checksum, rotating right before each addition; 611590Srgrimes * overflow is discarded. 621590Srgrimes */ 6387212Smarkm lcrc = total = 0; 641590Srgrimes while ((nr = read(fd, buf, sizeof(buf))) > 0) 651590Srgrimes for (total += nr, p = buf; nr--; ++p) { 6687212Smarkm if (lcrc & 1) 6787212Smarkm lcrc |= 0x10000; 6887212Smarkm lcrc = ((lcrc >> 1) + *p) & 0xffff; 691590Srgrimes } 701590Srgrimes if (nr < 0) 71112212Srobert return (1); 721590Srgrimes 7387212Smarkm *cval = lcrc; 741590Srgrimes *clen = total; 75112212Srobert return (0); 761590Srgrimes} 77