Home | History | Annotate | Line # | Download | only in cksum
sum2.c revision 1.5 
      1 /*	$NetBSD: sum2.c,v 1.5 1996/02/27 21:17:28 cgd Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1991, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #ifndef lint
     37 #if 0
     38 static char sccsid[] = "@(#)sum2.c	8.1 (Berkeley) 6/6/93";
     39 #else
     40 static char rcsid[] = "$NetBSD: sum2.c,v 1.5 1996/02/27 21:17:28 cgd Exp $";
     41 #endif
     42 #endif /* not lint */
     43 
     44 #include <sys/types.h>
     45 #include <unistd.h>
     46 
     47 #include "extern.h"
     48 
     49 int
     50 csum2(fd, cval, clen)
     51 	register int fd;
     52 	u_int32_t *cval, *clen;
     53 {
     54 	register u_int32_t crc, total;
     55 	register int nr;
     56 	register u_char *p;
     57 	u_char buf[8192];
     58 
     59 	/*
     60 	 * Draft 8 POSIX 1003.2:
     61 	 *
     62 	 *   s = sum of all bytes
     63 	 *   r = s % 2^16 + (s % 2^32) / 2^16
     64 	 * crc = (r % 2^16) + r / 2^16
     65 	 */
     66 	crc = total = 0;
     67 	while ((nr = read(fd, buf, sizeof(buf))) > 0)
     68 		for (total += nr, p = buf; nr--; ++p)
     69 			crc += *p;
     70 	if (nr < 0)
     71 		return(1);
     72 
     73 	crc = (crc & 0xffff) + (crc >> 16);
     74 	crc = (crc & 0xffff) + (crc >> 16);
     75 
     76 	*cval = crc;
     77 	*clen = total;
     78 	return(0);
     79 }
     80