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installboot.c revision 1.12
      1 /*	$NetBSD: installboot.c,v 1.12 2001/10/14 19:45:53 leo Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1995 Waldi Ravens
      5  * 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 Waldi Ravens.
     18  * 4. The name of the author may not be used to endorse or promote products
     19  *    derived from this software without specific prior written permission
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     22  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     23  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     24  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     26  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     27  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     28  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     30  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     31  */
     32 
     33 #include <sys/types.h>
     34 #include <sys/param.h>
     35 #include <sys/sysctl.h>
     36 #include <sys/ioctl.h>
     37 #include <unistd.h>
     38 #include <string.h>
     39 #include <stdlib.h>
     40 #include <stdio.h>
     41 #include <paths.h>
     42 #include <fcntl.h>
     43 #include <errno.h>
     44 #include <err.h>
     45 #include <limits.h>
     46 #include <nlist.h>
     47 #include <kvm.h>
     48 
     49 #define	DKTYPENAMES
     50 #define	FSTYPENAMES
     51 #include <sys/disklabel.h>
     52 #include <machine/ahdilabel.h>
     53 
     54 #include "installboot.h"
     55 
     56 static void	usage __P((void));
     57 static void	oscheck __P((void));
     58 static u_int	abcksum __P((void *));
     59 static void	setNVpref __P((void));
     60 static void	setIDEpar __P((u_int8_t *, size_t));
     61 static void	mkahdiboot __P((struct ahdi_root *, char *,
     62 						char *, daddr_t));
     63 static void	mkbootblock __P((struct bootblock *, char *,
     64 				char *, struct disklabel *, u_int));
     65 static void	install_fd __P((char *, struct disklabel *));
     66 static void	install_sd __P((char *, struct disklabel *));
     67 static void	install_wd __P((char *, struct disklabel *));
     68 
     69 static struct bootblock	bootarea;
     70 static struct ahdi_root ahdiboot;
     71 static const char	mdecpath[] = PATH_MDEC;
     72 static int		nowrite = 0;
     73 static int		verbose = 0;
     74 static int		trackpercyl = 0;
     75 static int		secpertrack = 0;
     76 
     77 static void
     78 usage ()
     79 {
     80 	fprintf(stderr,
     81 		"usage: installboot [options] device\n"
     82 		"where options are:\n"
     83 		"\t-N  do not actually write anything on the disk\n"
     84 		"\t-t  number of tracks per cylinder (IDE disk)\n"
     85 		"\t-u  number of sectors per track (IDE disk)\n"
     86 		"\t-v  verbose mode\n");
     87 	exit(EXIT_FAILURE);
     88 }
     89 
     90 int
     91 main (argc, argv)
     92 	int	argc;
     93 	char	*argv[];
     94 {
     95 	struct disklabel dl;
     96 	char		 *dn;
     97 	int		 fd, c;
     98 
     99 	/* check OS bootversion */
    100 	oscheck();
    101 
    102 	/* parse options */
    103 	while ((c = getopt(argc, argv, "Nt:u:v")) != -1) {
    104 		switch (c) {
    105 		  case 'N':
    106 			nowrite = 1;
    107 			break;
    108 		  case 't':
    109 			trackpercyl = atoi(optarg);
    110 			break;
    111 		  case 'u':
    112 			secpertrack = atoi(optarg);
    113 			break;
    114 		  case 'v':
    115 			verbose = 1;
    116 			break;
    117 		  default:
    118 			usage();
    119 		}
    120 	}
    121 	argv += optind;
    122 	argc -= optind;
    123 	if (argc != 1)
    124 		usage();
    125 
    126 	/* get disk label */
    127 	dn = alloca(sizeof(_PATH_DEV) + strlen(argv[0]) + 8);
    128 	if (!strchr(argv[0], '/')) {
    129 		sprintf(dn, "%sr%s%c", _PATH_DEV, argv[0], RAW_PART + 'a');
    130 		fd = open(dn, O_RDONLY);
    131 		if (fd < 0 && errno == ENOENT) {
    132 			sprintf(dn, "%sr%s", _PATH_DEV, argv[0]);
    133 			fd = open(dn, O_RDONLY);
    134 		}
    135 	} else {
    136 		sprintf(dn, "%s", argv[0]);
    137 		fd = open(dn, O_RDONLY);
    138 	}
    139 	if (fd < 0)
    140 		err(EXIT_FAILURE, "%s", dn);
    141 	if (ioctl(fd, DIOCGDINFO, &dl))
    142 		err(EXIT_FAILURE, "%s: DIOCGDINFO", dn);
    143 	if (close(fd))
    144 		err(EXIT_FAILURE, "%s", dn);
    145 
    146 	switch (dl.d_type) {
    147 		case DTYPE_FLOPPY:
    148 			install_fd(dn, &dl);
    149 			break;
    150 		case DTYPE_ST506:
    151 		case DTYPE_ESDI:
    152 			install_wd(dn, &dl);
    153 			setNVpref();
    154 			break;
    155 		case DTYPE_SCSI:
    156 			install_sd(dn, &dl);
    157 			setNVpref();
    158 			break;
    159 		default:
    160 			errx(EXIT_FAILURE,
    161 			     "%s: %s: Device type not supported.",
    162 			     dn, dktypenames[dl.d_type]);
    163 	}
    164 
    165 	return(EXIT_SUCCESS);
    166 }
    167 
    168 static void
    169 oscheck ()
    170 {
    171 	struct nlist	kbv[] = { { "_bootversion" },
    172 				  { NULL } };
    173 	kvm_t		*kd_kern;
    174 	char		errbuf[_POSIX2_LINE_MAX];
    175 	u_short		kvers;
    176 
    177 	kd_kern = kvm_openfiles(NULL, NULL, NULL, O_RDONLY, errbuf);
    178 	if (kd_kern == NULL)
    179 		errx(EXIT_FAILURE, "kvm_openfiles: %s", errbuf);
    180 	if (kvm_nlist(kd_kern, kbv) == -1)
    181 		errx(EXIT_FAILURE, "kvm_nlist: %s", kvm_geterr(kd_kern));
    182 	if (kbv[0].n_value == 0)
    183 		errx(EXIT_FAILURE, "%s not in namelist", kbv[0].n_name);
    184 	if (kvm_read(kd_kern, kbv[0].n_value, (char *)&kvers,
    185 						sizeof(kvers)) == -1)
    186 		errx(EXIT_FAILURE, "kvm_read: %s", kvm_geterr(kd_kern));
    187 	kvm_close(kd_kern);
    188 	if (kvers != BOOTVERSION)
    189 		errx(EXIT_FAILURE, "Kern bootversion: %d, expected: %d\n",
    190 					kvers, BOOTVERSION);
    191 }
    192 
    193 static void
    194 install_fd (devnm, label)
    195 	char		 *devnm;
    196 	struct disklabel *label;
    197 {
    198 	char		 *xxboot, *bootxx;
    199 	struct partition *rootpart;
    200 
    201 	if (label->d_secsize != 512)
    202 		errx(EXIT_FAILURE,
    203 		     "%s: %u: Block size not supported.", devnm,
    204 							  label->d_secsize);
    205 	if (label->d_ntracks != 2)
    206 		errx(EXIT_FAILURE,
    207 		     "%s: Single sided floppy not supported.", devnm);
    208 
    209 	xxboot = alloca(strlen(mdecpath) + 8);
    210 	sprintf(xxboot, "%sfdboot", mdecpath);
    211 	bootxx = alloca(strlen(mdecpath) + 8);
    212 	sprintf(bootxx, "%sbootxx", mdecpath);
    213 
    214 	/* first used partition (a, b or c) */		/* XXX */
    215 	for (rootpart = label->d_partitions; ; ++rootpart) {
    216 		if (rootpart->p_size)
    217 			break;
    218 	}
    219 	if (rootpart != label->d_partitions) {		/* XXX */
    220 		*(label->d_partitions) = *rootpart;
    221 		memset(rootpart, 0, sizeof(*rootpart));
    222 	}
    223 	label->d_partitions->p_fstype = FS_BSDFFS;	/* XXX */
    224 	label->d_npartitions = 1;
    225 	label->d_checksum = 0;
    226 	label->d_checksum = dkcksum(label);
    227 
    228 	trackpercyl = secpertrack = 0;
    229 	mkbootblock(&bootarea, xxboot, bootxx, label, 0);
    230 
    231 	if (!nowrite) {
    232 		int	fd;
    233 		if ((fd = open(devnm, O_WRONLY)) < 0)
    234 			err(EXIT_FAILURE, "%s", devnm);
    235 		if (write(fd, &bootarea, sizeof(bootarea)) != sizeof(bootarea))
    236 			err(EXIT_FAILURE, "%s", devnm);
    237 		if (close(fd))
    238 			err(EXIT_FAILURE, "%s", devnm);
    239 		if (verbose)
    240 			printf("Boot block installed on %s\n", devnm);
    241 	}
    242 }
    243 
    244 static void
    245 install_sd (devnm, label)
    246 	char		 *devnm;
    247 	struct disklabel *label;
    248 {
    249 	char		 *xxb00t, *xxboot, *bootxx;
    250 	struct disklabel rawlabel;
    251 	daddr_t		 bbsec;
    252 	u_int		 magic;
    253 
    254 	if (label->d_partitions[0].p_size == 0)
    255 		errx(EXIT_FAILURE, "%s: No root-filesystem.", devnm);
    256 	if (label->d_partitions[0].p_fstype != FS_BSDFFS)
    257 		errx(EXIT_FAILURE, "%s: %s: Illegal root-filesystem type.",
    258 		     devnm, fstypenames[label->d_partitions[0].p_fstype]);
    259 
    260 	bbsec = readdisklabel(devnm, &rawlabel);
    261 	if (bbsec == NO_BOOT_BLOCK)
    262 		errx(EXIT_FAILURE, "%s: No NetBSD boot block.", devnm);
    263 	if (memcmp(label, &rawlabel, sizeof(*label)))
    264 		errx(EXIT_FAILURE, "%s: Invalid NetBSD boot block.", devnm);
    265 
    266 	if (bbsec) {
    267 		xxb00t = alloca(strlen(mdecpath) + 14);
    268 		sprintf(xxb00t, "%ssdb00t.ahdi", mdecpath);
    269 		xxboot = alloca(strlen(mdecpath) + 14);
    270 		sprintf(xxboot, "%sxxboot.ahdi", mdecpath);
    271 		magic = AHDIMAGIC;
    272 	} else {
    273 		xxb00t = NULL;
    274 		xxboot = alloca(strlen(mdecpath) + 8);
    275 		sprintf(xxboot, "%ssdboot", mdecpath);
    276 		magic = NBDAMAGIC;
    277 	}
    278 	bootxx = alloca(strlen(mdecpath) + 8);
    279 	sprintf(bootxx, "%sbootxx", mdecpath);
    280 
    281 	trackpercyl = secpertrack = 0;
    282 	if (xxb00t)
    283 		mkahdiboot(&ahdiboot, xxb00t, devnm, bbsec);
    284 	mkbootblock(&bootarea, xxboot, bootxx, label, magic);
    285 
    286 	if (!nowrite) {
    287 		off_t	bbo = bbsec * AHDI_BSIZE;
    288 		int	fd;
    289 
    290 		if ((fd = open(devnm, O_WRONLY)) < 0)
    291 			err(EXIT_FAILURE, "%s", devnm);
    292 		if (lseek(fd, bbo, SEEK_SET) != bbo)
    293 			err(EXIT_FAILURE, "%s", devnm);
    294 		if (write(fd, &bootarea, sizeof(bootarea)) != sizeof(bootarea))
    295 			err(EXIT_FAILURE, "%s", devnm);
    296 		if (verbose)
    297 			printf("Boot block installed on %s (%u)\n", devnm,
    298 								    bbsec);
    299 		if (xxb00t) {
    300 			if (lseek(fd, (off_t)0, SEEK_SET) != 0)
    301 				err(EXIT_FAILURE, "%s", devnm);
    302 			if (write(fd, &ahdiboot, sizeof(ahdiboot)) != sizeof(ahdiboot))
    303 				err(EXIT_FAILURE, "%s", devnm);
    304 			if (verbose)
    305 				printf("AHDI root  installed on %s (0)\n",
    306 								devnm);
    307 		}
    308 		if (close(fd))
    309 			err(EXIT_FAILURE, "%s", devnm);
    310 	}
    311 }
    312 
    313 static void
    314 install_wd (devnm, label)
    315 	char		 *devnm;
    316 	struct disklabel *label;
    317 {
    318 	char		 *xxb00t, *xxboot, *bootxx;
    319 	struct disklabel rawlabel;
    320 	daddr_t		 bbsec;
    321 	u_int		 magic;
    322 
    323 	if (label->d_partitions[0].p_size == 0)
    324 		errx(EXIT_FAILURE, "%s: No root-filesystem.", devnm);
    325 	if (label->d_partitions[0].p_fstype != FS_BSDFFS)
    326 		errx(EXIT_FAILURE, "%s: %s: Illegal root-filesystem type.",
    327 		     devnm, fstypenames[label->d_partitions[0].p_fstype]);
    328 
    329 	bbsec = readdisklabel(devnm, &rawlabel);
    330 	if (bbsec == NO_BOOT_BLOCK)
    331 		errx(EXIT_FAILURE, "%s: No NetBSD boot block.", devnm);
    332 	if (memcmp(label, &rawlabel, sizeof(*label)))
    333 		errx(EXIT_FAILURE, "%s: Invalid NetBSD boot block.", devnm);
    334 
    335 	if (bbsec) {
    336 		xxb00t = alloca(strlen(mdecpath) + 14);
    337 		sprintf(xxb00t, "%swdb00t.ahdi", mdecpath);
    338 		xxboot = alloca(strlen(mdecpath) + 14);
    339 		sprintf(xxboot, "%sxxboot.ahdi", mdecpath);
    340 		magic = AHDIMAGIC;
    341 	} else {
    342 		xxb00t = NULL;
    343 		xxboot = alloca(strlen(mdecpath) + 8);
    344 		sprintf(xxboot, "%swdboot", mdecpath);
    345 		magic = NBDAMAGIC;
    346 	}
    347 	bootxx = alloca(strlen(mdecpath) + 8);
    348 	sprintf(bootxx, "%sbootxx", mdecpath);
    349 
    350 	if (xxb00t)
    351 		mkahdiboot(&ahdiboot, xxb00t, devnm, bbsec);
    352 	mkbootblock(&bootarea, xxboot, bootxx, label, magic);
    353 
    354 	if (!nowrite) {
    355 		int	fd;
    356 		off_t	bbo;
    357 
    358 		bbo = bbsec * AHDI_BSIZE;
    359 		if ((fd = open(devnm, O_WRONLY)) < 0)
    360 			err(EXIT_FAILURE, "%s", devnm);
    361 		if (lseek(fd, bbo, SEEK_SET) != bbo)
    362 			err(EXIT_FAILURE, "%s", devnm);
    363 		if (write(fd, &bootarea, sizeof(bootarea)) != sizeof(bootarea))
    364 			err(EXIT_FAILURE, "%s", devnm);
    365 		if (verbose)
    366 			printf("Boot block installed on %s (%u)\n", devnm,
    367 								    bbsec);
    368 		if (xxb00t) {
    369 			if (lseek(fd, (off_t)0, SEEK_SET) != 0)
    370 				err(EXIT_FAILURE, "%s", devnm);
    371 			if (write(fd, &ahdiboot, sizeof(ahdiboot))
    372 							!= sizeof(ahdiboot))
    373 				err(EXIT_FAILURE, "%s", devnm);
    374 			if (verbose)
    375 				printf("AHDI root  installed on %s (0)\n",
    376 									devnm);
    377 		}
    378 		if (close(fd))
    379 			err(EXIT_FAILURE, "%s", devnm);
    380 	}
    381 }
    382 
    383 static void
    384 mkahdiboot (newroot, xxb00t, devnm, bbsec)
    385 	struct ahdi_root *newroot;
    386 	char		 *xxb00t,
    387 			 *devnm;
    388 	daddr_t		 bbsec;
    389 {
    390 	struct ahdi_root tmproot;
    391 	struct ahdi_part *pd;
    392 	int		 fd;
    393 
    394 	/* read prototype root-sector */
    395 	if ((fd = open(xxb00t, O_RDONLY)) < 0)
    396 		err(EXIT_FAILURE, "%s", xxb00t);
    397 	if (read(fd, &tmproot, sizeof(tmproot)) != sizeof(tmproot))
    398 		err(EXIT_FAILURE, "%s", xxb00t);
    399 	if (close(fd))
    400 		err(EXIT_FAILURE, "%s", xxb00t);
    401 
    402 	/* set tracks/cylinder and sectors/track */
    403 	setIDEpar(tmproot.ar_fill, sizeof(tmproot.ar_fill));
    404 
    405 	/* read current root-sector */
    406 	if ((fd = open(devnm, O_RDONLY)) < 0)
    407 		err(EXIT_FAILURE, "%s", devnm);
    408 	if (read(fd, newroot, sizeof(*newroot)) != sizeof(*newroot))
    409 		err(EXIT_FAILURE, "%s", devnm);
    410 	if (close(fd))
    411 		err(EXIT_FAILURE, "%s", devnm);
    412 
    413 	/* set bootflags */
    414 	for (pd = newroot->ar_parts; pd-newroot->ar_parts < AHDI_MAXRPD; ++pd) {
    415 		if (pd->ap_st == bbsec) {
    416 			pd->ap_flg = 0x21;	/* bootable, pref = NetBSD */
    417 			goto gotit;
    418 		}
    419 	}
    420 	errx(EXIT_FAILURE,
    421 	     "%s: NetBSD boot block not on primary AHDI partition.", devnm);
    422 
    423 gotit:	/* copy code from prototype and set new checksum */
    424 	memcpy(newroot->ar_fill, tmproot.ar_fill, sizeof(tmproot.ar_fill));
    425 	newroot->ar_checksum = 0;
    426 	newroot->ar_checksum = 0x1234 - abcksum(newroot);
    427 
    428 	if (verbose)
    429 		printf("AHDI      boot loader: %s\n", xxb00t);
    430 }
    431 
    432 static void
    433 mkbootblock (bb, xxb, bxx, label, magic)
    434 	struct bootblock *bb;
    435 	char		 *xxb,
    436 			 *bxx;
    437 	u_int		 magic;
    438 	struct disklabel *label;
    439 {
    440 	int		 fd;
    441 
    442 	memset(bb, 0, sizeof(*bb));
    443 
    444 	/* set boot block magic */
    445 	bb->bb_magic = magic;
    446 
    447 	/* set disk pack label */
    448 	BBSETLABEL(bb, label);
    449 
    450 	/* set second-stage boot loader */
    451 	if ((fd = open(bxx, O_RDONLY)) < 0)
    452 		err(EXIT_FAILURE, "%s", bxx);
    453 	if (read(fd, bb->bb_bootxx, sizeof(bb->bb_bootxx))
    454 					!= sizeof(bb->bb_bootxx))
    455 		err(EXIT_FAILURE, "%s", bxx);
    456 	if (close(fd))
    457 		err(EXIT_FAILURE, "%s", bxx);
    458 
    459 	/* set first-stage bootloader */
    460 	if ((fd = open(xxb, O_RDONLY)) < 0)
    461 		err(EXIT_FAILURE, "%s", xxb);
    462 	if (read(fd, bb->bb_xxboot, sizeof(bb->bb_xxboot))
    463 					!= sizeof(bb->bb_xxboot))
    464 		err(EXIT_FAILURE, "%s", xxb);
    465 	if (close(fd))
    466 		err(EXIT_FAILURE, "%s", xxb);
    467 
    468 	/* set tracks/cylinder and sectors/track */
    469 	setIDEpar(bb->bb_xxboot, sizeof(bb->bb_xxboot));
    470 
    471 	/* set AHDI checksum */
    472 	*((u_int16_t *)bb->bb_xxboot + 255) = 0;
    473 	*((u_int16_t *)bb->bb_xxboot + 255) = 0x1234 - abcksum(bb->bb_xxboot);
    474 
    475 	if (verbose) {
    476 		printf("Primary   boot loader: %s\n", xxb);
    477 		printf("Secondary boot loader: %s\n", bxx);
    478 	}
    479 }
    480 
    481 static void
    482 setIDEpar (start, size)
    483 	u_int8_t	*start;
    484 	size_t		size;
    485 {
    486 	static const u_int8_t	mark[] = { 'N', 'e', 't', 'B', 'S', 'D' };
    487 
    488 	if ((u_int)trackpercyl > 255)
    489 		errx(EXIT_FAILURE,
    490 		     "%d: Illegal tracks/cylinder value (1..255)", trackpercyl);
    491 	if ((u_int)secpertrack > 255)
    492 		errx(EXIT_FAILURE,
    493 		     "%d: Illegal sectors/track value (1..255)", secpertrack);
    494 
    495 	if (trackpercyl || secpertrack) {
    496 		u_int8_t *p;
    497 
    498 		if (!trackpercyl)
    499 			errx(EXIT_FAILURE, "Need tracks/cylinder too.");
    500 		if (!secpertrack)
    501 			errx(EXIT_FAILURE, "Need sectors/track too.");
    502 
    503 		start += 2;
    504 		size  -= sizeof(mark) + 2;
    505 		for (p = start + size; p >= start; --p) {
    506 			if (*p != *mark)
    507 				continue;
    508 			if (!memcmp(p, mark, sizeof(mark)))
    509 				break;
    510 		}
    511 		if (p < start)
    512 			errx(EXIT_FAILURE,
    513 			     "Malformatted xxboot prototype.");
    514 
    515 		*--p = secpertrack;
    516 		*--p = trackpercyl;
    517 
    518 		if (verbose) {
    519 			printf("sectors/track  : %d\n", secpertrack);
    520 			printf("tracks/cylinder: %d\n", trackpercyl);
    521 		}
    522 	}
    523 }
    524 
    525 static void
    526 setNVpref ()
    527 {
    528 	static const u_char	bootpref = BOOTPREF_NETBSD;
    529 	static const char	nvrdev[] = PATH_NVRAM;
    530 
    531 	if (!nowrite) {
    532 		int	fd;
    533 
    534 		if ((fd = open(nvrdev, O_RDWR)) < 0)
    535 			err(EXIT_FAILURE, "%s", nvrdev);
    536 		if (lseek(fd, (off_t)1, SEEK_SET) != 1)
    537 			err(EXIT_FAILURE, "%s", nvrdev);
    538 		if (write(fd, &bootpref, (size_t)1) != 1)
    539 			err(EXIT_FAILURE, "%s", nvrdev);
    540 		if (close(fd))
    541 			err(EXIT_FAILURE, "%s", nvrdev);
    542 		if (verbose)
    543 			printf("Boot preference set to NetBSD.\n");
    544 	}
    545 }
    546 
    547 static u_int
    548 abcksum (bs)
    549 	void	*bs;
    550 {
    551 	u_int16_t sum  = 0,
    552 		  *st  = (u_int16_t *)bs,
    553 		  *end = (u_int16_t *)bs + 256;
    554 
    555 	while (st < end)
    556 		sum += *st++;
    557 	return(sum);
    558 }
    559