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 30 #ifndef lint 31 #if 0 32 static char sccsid[] = "@(#)sum1.c 8.1 (Berkeley) 6/6/93"; 33 #endif 34 #endif /* not lint */ 35 36 #include <sys/cdefs.h> 37 __FBSDID("$FreeBSD$"); 38 39 #include <sys/types.h> 40 41 #include <unistd.h> 42 #include <stdint.h> 43 44 #include "extern.h" 45 46 int 47 csum1(int fd, uint32_t *cval, off_t *clen) 48 { 49 int nr; 50 u_int lcrc; 51 off_t total; 52 u_char *p; 53 u_char buf[8192]; 54 55 /* 56 * 16-bit checksum, rotating right before each addition; 57 * overflow is discarded. 58 */ 59 lcrc = total = 0; 60 while ((nr = read(fd, buf, sizeof(buf))) > 0) 61 for (total += nr, p = buf; nr--; ++p) { 62 if (lcrc & 1) 63 lcrc |= 0x10000; 64 lcrc = ((lcrc >> 1) + *p) & 0xffff; 65 } 66 if (nr < 0) 67 return (1); 68 69 *cval = lcrc; 70 *clen = total; 71 return (0); 72 } 73