xref: /freebsd/sbin/fdisk/fdisk.c (revision 87b759f0fa1f7554d50ce640c40138512bbded44)
1 /*
2  * Mach Operating System
3  * Copyright (c) 1992 Carnegie Mellon University
4  * All Rights Reserved.
5  *
6  * Permission to use, copy, modify and distribute this software and its
7  * documentation is hereby granted, provided that both the copyright
8  * notice and this permission notice appear in all copies of the
9  * software, derivative works or modified versions, and any portions
10  * thereof, and that both notices appear in supporting documentation.
11  *
12  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
13  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
14  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
15  *
16  * Carnegie Mellon requests users of this software to return to
17  *
18  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
19  *  School of Computer Science
20  *  Carnegie Mellon University
21  *  Pittsburgh PA 15213-3890
22  *
23  * any improvements or extensions that they make and grant Carnegie Mellon
24  * the rights to redistribute these changes.
25  */
26 
27 #include <sys/cdefs.h>
28 #include <sys/disk.h>
29 #include <sys/disklabel.h>
30 #include <sys/diskmbr.h>
31 #include <sys/endian.h>
32 #include <sys/param.h>
33 #include <sys/stat.h>
34 #include <sys/mount.h>
35 #include <ctype.h>
36 #include <fcntl.h>
37 #include <err.h>
38 #include <errno.h>
39 #include <libgeom.h>
40 #include <paths.h>
41 #include <regex.h>
42 #include <stdint.h>
43 #include <stdio.h>
44 #include <stdlib.h>
45 #include <string.h>
46 #include <unistd.h>
47 
48 #include "fdisk_mbr_enc.h"
49 
50 static int iotest;
51 
52 #define NO_DISK_SECTORS ((u_int32_t)-1)
53 #define NO_TRACK_CYLINDERS 1023
54 #define NO_TRACK_HEADS 255
55 #define NO_TRACK_SECTORS 63
56 #define LBUF 100
57 static char lbuf[LBUF];
58 
59 /*
60  *
61  * Ported to 386bsd by Julian Elischer  Thu Oct 15 20:26:46 PDT 1992
62  *
63  * 14-Dec-89  Robert Baron (rvb) at Carnegie-Mellon University
64  *	Copyright (c) 1989	Robert. V. Baron
65  *	Created.
66  */
67 
68 #define Decimal(str, ans, tmp, maxval) if (decimal(str, &tmp, ans, maxval)) ans = tmp
69 
70 #define MAX_SEC_SIZE 65536	/* maximum sector size that is supported */
71 #define MIN_SEC_SIZE 512	/* the sector size to start sensing at */
72 static int secsize = 0;		/* the sensed sector size */
73 
74 static char *disk;
75 
76 static int cyls, sectors, heads, cylsecs;
77 static u_int32_t disksecs;
78 
79 struct mboot {
80 	unsigned char *bootinst;  /* boot code */
81 	off_t bootinst_size;
82 	struct	dos_partition parts[NDOSPART];
83 };
84 
85 static struct mboot mboot;
86 static int fd;
87 
88 #define ACTIVE 0x80
89 
90 static uint dos_cyls;
91 static uint dos_heads;
92 static uint dos_sectors;
93 static uint dos_cylsecs;
94 
95 #define DOSSECT(s,c) ((s & 0x3f) | ((c >> 2) & 0xc0))
96 #define DOSCYL(c)	(c & 0xff)
97 
98 #define MAX_ARGS	10
99 
100 static int	current_line_number;
101 
102 static int	geom_processed = 0;
103 static int	part_processed = 0;
104 static int	active_processed = 0;
105 
106 typedef struct cmd {
107     char		cmd;
108     int			n_args;
109     struct arg {
110 	char		argtype;
111 	unsigned long	arg_val;
112 	char *		arg_str;
113     }			args[MAX_ARGS];
114 } CMD;
115 
116 static int B_flag  = 0;		/* replace boot code */
117 static int I_flag  = 0;		/* use entire disk for FreeBSD */
118 static int a_flag  = 0;		/* set active partition */
119 static char *b_flag = NULL;	/* path to boot code */
120 static int i_flag  = 0;		/* replace partition data */
121 static int q_flag  = 0;		/* Be quiet */
122 static int u_flag  = 0;		/* update partition data */
123 static int s_flag  = 0;		/* Print a summary and exit */
124 static int t_flag  = 0;		/* test only */
125 static char *f_flag = NULL;	/* Read config info from file */
126 static int v_flag  = 0;		/* Be verbose */
127 static int print_config_flag = 0;
128 
129 /*
130  * A list of partition types, probably outdated.
131  */
132 static const char *const part_types[256] = {
133 	[0x00] = "unused",
134 	[0x01] = "Primary DOS with 12 bit FAT",
135 	[0x02] = "XENIX / file system",
136 	[0x03] = "XENIX /usr file system",
137 	[0x04] = "Primary DOS with 16 bit FAT (< 32MB)",
138 	[0x05] = "Extended DOS",
139 	[0x06] = "Primary DOS, 16 bit FAT (>= 32MB)",
140 	[0x07] = "NTFS, OS/2 HPFS, QNX-2 (16 bit) or Advanced UNIX",
141 	[0x08] = "AIX file system or SplitDrive",
142 	[0x09] = "AIX boot partition or Coherent",
143 	[0x0A] = "OS/2 Boot Manager, OPUS or Coherent swap",
144 	[0x0B] = "DOS or Windows 95 with 32 bit FAT",
145 	[0x0C] = "DOS or Windows 95 with 32 bit FAT (LBA)",
146 	[0x0E] = "Primary 'big' DOS (>= 32MB, LBA)",
147 	[0x0F] = "Extended DOS (LBA)",
148 	[0x10] = "OPUS",
149 	[0x11] = "OS/2 BM: hidden DOS with 12-bit FAT",
150 	[0x12] = "Compaq diagnostics",
151 	[0x14] = "OS/2 BM: hidden DOS with 16-bit FAT (< 32MB)",
152 	[0x16] = "OS/2 BM: hidden DOS with 16-bit FAT (>= 32MB)",
153 	[0x17] = "OS/2 BM: hidden IFS (e.g. HPFS)",
154 	[0x18] = "AST Windows swapfile",
155 	[0x1b] = "ASUS Recovery partition (NTFS)",
156 	[0x24] = "NEC DOS",
157 	[0x3C] = "PartitionMagic recovery",
158 	[0x39] = "plan9",
159 	[0x40] = "VENIX 286",
160 	[0x41] = "Linux/MINIX (sharing disk with DRDOS)",
161 	[0x42] = "SFS or Linux swap (sharing disk with DRDOS)",
162 	[0x43] = "Linux native (sharing disk with DRDOS)",
163 	[0x4D] = "QNX 4.2 Primary",
164 	[0x4E] = "QNX 4.2 Secondary",
165 	[0x4F] = "QNX 4.2 Tertiary",
166 	[0x50] = "DM (disk manager)",
167 	[0x51] = "DM6 Aux1 (or Novell)",
168 	[0x52] = "CP/M or Microport SysV/AT",
169 	[0x53] = "DM6 Aux3",
170 	[0x54] = "DM6",
171 	[0x55] = "EZ-Drive (disk manager)",
172 	[0x56] = "Golden Bow (disk manager)",
173 	[0x5c] = "Priam Edisk (disk manager)", /* according to S. Widlake */
174 	[0x61] = "SpeedStor",
175 	[0x63] = "System V/386 (such as ISC UNIX), GNU HURD or Mach",
176 	[0x64] = "Novell Netware/286 2.xx",
177 	[0x65] = "Novell Netware/386 3.xx",
178 	[0x6C] = "DragonFlyBSD",
179 	[0x70] = "DiskSecure Multi-Boot",
180 	[0x75] = "PCIX",
181 	[0x77] = "QNX4.x",
182 	[0x78] = "QNX4.x 2nd part",
183 	[0x79] = "QNX4.x 3rd part",
184 	[0x80] = "Minix until 1.4a",
185 	[0x81] = "Minix since 1.4b, early Linux partition or Mitac disk manager",
186 	[0x82] = "Linux swap or Solaris x86",
187 	[0x83] = "Linux native",
188 	[0x84] = "OS/2 hidden C: drive",
189 	[0x85] = "Linux extended",
190 	[0x86] = "NTFS volume set??",
191 	[0x87] = "NTFS volume set??",
192 	[0x93] = "Amoeba file system",
193 	[0x94] = "Amoeba bad block table",
194 	[0x9F] = "BSD/OS",
195 	[0xA0] = "Suspend to Disk",
196 	[0xA5] = "FreeBSD/NetBSD/386BSD",
197 	[0xA6] = "OpenBSD",
198 	[0xA7] = "NeXTSTEP",
199 	[0xA9] = "NetBSD",
200 	[0xAC] = "IBM JFS",
201 	[0xAF] = "HFS+",
202 	[0xB7] = "BSDI BSD/386 file system",
203 	[0xB8] = "BSDI BSD/386 swap",
204 	[0xBE] = "Solaris x86 boot",
205 	[0xBF] = "Solaris x86 (new)",
206 	[0xC1] = "DRDOS/sec with 12-bit FAT",
207 	[0xC4] = "DRDOS/sec with 16-bit FAT (< 32MB)",
208 	[0xC6] = "DRDOS/sec with 16-bit FAT (>= 32MB)",
209 	[0xC7] = "Syrinx",
210 	[0xDB] = "CP/M, Concurrent CP/M, Concurrent DOS or CTOS",
211 	[0xDE] = "DELL Utilities - FAT filesystem",
212 	[0xE1] = "DOS access or SpeedStor with 12-bit FAT extended partition",
213 	[0xE3] = "DOS R/O or SpeedStor",
214 	[0xE4] = "SpeedStor with 16-bit FAT extended partition < 1024 cyl.",
215 	[0xEB] = "BeOS file system",
216 	[0xEE] = "EFI GPT",
217 	[0xEF] = "EFI System Partition",
218 	[0xF1] = "SpeedStor",
219 	[0xF2] = "DOS 3.3+ Secondary",
220 	[0xF4] = "SpeedStor large partition",
221 	[0xFB] = "VMware VMFS",
222 	[0xFE] = "SpeedStor >1024 cyl. or LANstep",
223 	[0xFF] = "Xenix bad blocks table",
224 };
225 
226 static const char *
227 get_type(int t)
228 {
229 	const char *ret;
230 
231 	ret = (t >= 0 && t <= 255) ? part_types[t] : NULL;
232 	return ret ? ret : "unknown";
233 }
234 
235 
236 static int geom_class_available(const char *);
237 static void print_s0(void);
238 static void print_part(const struct dos_partition *);
239 static void init_sector0(unsigned long start);
240 static void init_boot(void);
241 static void change_part(int i);
242 static void print_params(void);
243 static void change_active(int which);
244 static void change_code(void);
245 static void get_params_to_use(void);
246 static char *get_rootdisk(void);
247 static void dos(struct dos_partition *partp);
248 static int open_disk(int flag);
249 static ssize_t read_disk(off_t sector, void *buf);
250 static int write_disk(off_t sector, void *buf);
251 static int get_params(void);
252 static int read_s0(void);
253 static int write_s0(void);
254 static int ok(const char *str);
255 static int decimal(const char *str, int *num, int deflt, uint32_t maxval);
256 static int read_config(char *config_file);
257 static void reset_boot(void);
258 static int sanitize_partition(struct dos_partition *);
259 static void usage(void) __dead2;
260 
261 int
262 main(int argc, char *argv[])
263 {
264 	int	c, i;
265 	int	partition = -1;
266 	struct	dos_partition *partp;
267 
268 	while ((c = getopt(argc, argv, "BIab:f:ipqstuv1234")) != -1)
269 		switch (c) {
270 		case 'B':
271 			B_flag = 1;
272 			break;
273 		case 'I':
274 			I_flag = 1;
275 			break;
276 		case 'a':
277 			a_flag = 1;
278 			break;
279 		case 'b':
280 			b_flag = optarg;
281 			break;
282 		case 'f':
283 			f_flag = optarg;
284 			break;
285 		case 'i':
286 			i_flag = 1;
287 			break;
288 		case 'p':
289 			print_config_flag = 1;
290 			break;
291 		case 'q':
292 			q_flag = 1;
293 			break;
294 		case 's':
295 			s_flag = 1;
296 			break;
297 		case 't':
298 			t_flag = 1;
299 			break;
300 		case 'u':
301 			u_flag = 1;
302 			break;
303 		case 'v':
304 			v_flag = 1;
305 			break;
306 		case '1':
307 		case '2':
308 		case '3':
309 		case '4':
310 			partition = c - '0';
311 			break;
312 		default:
313 			usage();
314 		}
315 	if (f_flag || i_flag)
316 		u_flag = 1;
317 	if (t_flag)
318 		v_flag = 1;
319 	argc -= optind;
320 	argv += optind;
321 
322 	if (argc == 0) {
323 		disk = get_rootdisk();
324 	} else {
325 		disk = g_device_path(argv[0]);
326 		if (disk == NULL)
327 			err(1, "unable to get correct path for %s", argv[0]);
328 	}
329 	if (open_disk(u_flag) < 0)
330 		err(1, "cannot open disk %s", disk);
331 
332 	/* (abu)use mboot.bootinst to probe for the sector size */
333 	if ((mboot.bootinst = malloc(MAX_SEC_SIZE)) == NULL)
334 		err(1, "cannot allocate buffer to determine disk sector size");
335 	if (read_disk(0, mboot.bootinst) == -1)
336 		errx(1, "could not detect sector size");
337 	free(mboot.bootinst);
338 	mboot.bootinst = NULL;
339 
340 	if (print_config_flag) {
341 		if (read_s0())
342 			err(1, "read_s0");
343 
344 		printf("# %s\n", disk);
345 		printf("g c%d h%d s%d\n", dos_cyls, dos_heads, dos_sectors);
346 
347 		for (i = 0; i < NDOSPART; i++) {
348 			partp = &mboot.parts[i];
349 
350 			if (partp->dp_start == 0 && partp->dp_size == 0)
351 				continue;
352 
353 			printf("p %d 0x%02x %lu %lu\n", i + 1, partp->dp_typ,
354 			    (u_long)partp->dp_start, (u_long)partp->dp_size);
355 
356 			/* Fill flags for the partition. */
357 			if (partp->dp_flag & 0x80)
358 				printf("a %d\n", i + 1);
359 		}
360 		exit(0);
361 	}
362 	if (s_flag) {
363 		if (read_s0())
364 			err(1, "read_s0");
365 		printf("%s: %d cyl %d hd %d sec\n", disk, dos_cyls, dos_heads,
366 		    dos_sectors);
367 		printf("Part  %11s %11s Type Flags\n", "Start", "Size");
368 		for (i = 0; i < NDOSPART; i++) {
369 			partp = &mboot.parts[i];
370 			if (partp->dp_start == 0 && partp->dp_size == 0)
371 				continue;
372 			printf("%4d: %11lu %11lu 0x%02x 0x%02x\n", i + 1,
373 			    (u_long) partp->dp_start,
374 			    (u_long) partp->dp_size, partp->dp_typ,
375 			    partp->dp_flag);
376 		}
377 		exit(0);
378 	}
379 
380 	printf("******* Working on device %s *******\n",disk);
381 
382 	if (I_flag) {
383 		if (read_s0())
384 			warnx("Ignoring bad existing MBR.");
385 		reset_boot();
386 		partp = &mboot.parts[0];
387 		partp->dp_typ = DOSPTYP_386BSD;
388 		partp->dp_flag = ACTIVE;
389 		partp->dp_start = dos_sectors;
390 		partp->dp_size = rounddown(disksecs, dos_cylsecs) -
391 		    dos_sectors;
392 		dos(partp);
393 		if (v_flag)
394 			print_s0();
395 		if (!t_flag)
396 			write_s0();
397 		exit(0);
398 	}
399 	if (f_flag) {
400 	    if (read_s0() || i_flag)
401 		reset_boot();
402 	    if (!read_config(f_flag))
403 		exit(1);
404 	    if (v_flag)
405 		print_s0();
406 	    if (!t_flag)
407 		write_s0();
408 	} else {
409 	    if(u_flag)
410 		get_params_to_use();
411 	    else
412 		print_params();
413 
414 	    if (read_s0()) {
415 		printf("Will replace existing bad MBR\n");
416 		init_sector0(dos_sectors);
417 	    }
418 
419 	    printf("Media sector size is %d\n", secsize);
420 	    printf("Warning: BIOS sector numbering starts with sector 1\n");
421 	    printf("Information from DOS bootblock is:\n");
422 	    if (partition == -1)
423 		for (i = 1; i <= NDOSPART; i++)
424 		    change_part(i);
425 	    else
426 		change_part(partition);
427 
428 	    if (u_flag || a_flag)
429 		change_active(partition);
430 
431 	    if (B_flag)
432 		change_code();
433 
434 	    if (u_flag || a_flag || B_flag) {
435 		if (!t_flag) {
436 		    printf("\nWe haven't changed the partition table yet.  ");
437 		    printf("This is your last chance.\n");
438 		}
439 		print_s0();
440 		if (!t_flag) {
441 		    if (ok("Should we write new partition table?"))
442 			write_s0();
443 		} else {
444 		    printf("\n-t flag specified -- partition table not written.\n");
445 		}
446 	    }
447 	}
448 
449 	exit(0);
450 }
451 
452 static void
453 usage(void)
454 {
455 	fprintf(stderr, "%s%s",
456 		"usage: fdisk [-BIaipqstu] [-b bootcode] [-1234] [disk]\n",
457  		"       fdisk -f configfile [-itv] [disk]\n");
458         exit(1);
459 }
460 
461 static void
462 print_s0(void)
463 {
464 	int	i;
465 
466 	print_params();
467 	printf("Information from DOS bootblock is:\n");
468 	for (i = 1; i <= NDOSPART; i++) {
469 		printf("%d: ", i);
470 		print_part(&mboot.parts[i - 1]);
471 	}
472 }
473 
474 static struct dos_partition mtpart;
475 
476 static void
477 print_part(const struct dos_partition *partp)
478 {
479 	u_int64_t part_mb;
480 
481 	if (!bcmp(partp, &mtpart, sizeof (struct dos_partition))) {
482 		printf("<UNUSED>\n");
483 		return;
484 	}
485 	/*
486 	 * Be careful not to overflow.
487 	 */
488 	part_mb = partp->dp_size;
489 	part_mb *= secsize;
490 	part_mb /= (1024 * 1024);
491 	printf("sysid %d (%#04x),(%s)\n", partp->dp_typ, partp->dp_typ,
492 	    get_type(partp->dp_typ));
493 	printf("    start %lu, size %lu (%ju Meg), flag %x%s\n",
494 		(u_long)partp->dp_start,
495 		(u_long)partp->dp_size,
496 		(uintmax_t)part_mb,
497 		partp->dp_flag,
498 		partp->dp_flag == ACTIVE ? " (active)" : "");
499 	printf("\tbeg: cyl %d/ head %d/ sector %d;\n\tend: cyl %d/ head %d/ sector %d\n"
500 		,DPCYL(partp->dp_scyl, partp->dp_ssect)
501 		,partp->dp_shd
502 		,DPSECT(partp->dp_ssect)
503 		,DPCYL(partp->dp_ecyl, partp->dp_esect)
504 		,partp->dp_ehd
505 		,DPSECT(partp->dp_esect));
506 }
507 
508 
509 static void
510 init_boot(void)
511 {
512 	const char *fname;
513 	int fdesc, n;
514 	struct stat sb;
515 
516 	fname = b_flag ? b_flag : "/boot/mbr";
517 	if ((fdesc = open(fname, O_RDONLY)) == -1 ||
518 	    fstat(fdesc, &sb) == -1)
519 		err(1, "%s", fname);
520 	if (sb.st_size == 0)
521 		errx(1, "%s is empty, must not be.", fname);
522 	if ((mboot.bootinst_size = sb.st_size) % secsize != 0)
523 		errx(1, "%s: length must be a multiple of sector size", fname);
524 	if (mboot.bootinst != NULL)
525 		free(mboot.bootinst);
526 	if ((mboot.bootinst = malloc(mboot.bootinst_size = sb.st_size)) == NULL)
527 		errx(1, "%s: unable to allocate read buffer", fname);
528 	if ((n = read(fdesc, mboot.bootinst, mboot.bootinst_size)) == -1 ||
529 	    close(fdesc))
530 		err(1, "%s", fname);
531 	if (n != mboot.bootinst_size)
532 		errx(1, "%s: short read", fname);
533 }
534 
535 
536 static void
537 init_sector0(unsigned long start)
538 {
539 	struct dos_partition *partp = &mboot.parts[0];
540 
541 	init_boot();
542 
543 	partp->dp_typ = DOSPTYP_386BSD;
544 	partp->dp_flag = ACTIVE;
545 	start = roundup(start, dos_sectors);
546 	if(start == 0)
547 		start = dos_sectors;
548 	partp->dp_start = start;
549 	partp->dp_size = rounddown(disksecs, dos_cylsecs) - start;
550 
551 	dos(partp);
552 }
553 
554 static void
555 change_part(int i)
556 {
557     struct dos_partition *partp = &mboot.parts[i - 1];
558 
559     printf("The data for partition %d is:\n", i);
560     print_part(partp);
561 
562     if (u_flag && ok("Do you want to change it?")) {
563 	int tmp;
564 
565 	if (i_flag) {
566 	    bzero(partp, sizeof (*partp));
567 	    if (i == 1) {
568 		init_sector0(1);
569 		printf("\nThe static data for the slice 1 has been reinitialized to:\n");
570 		print_part(partp);
571 	    }
572 	}
573 
574 	do {
575 		Decimal("sysid (165=FreeBSD)", partp->dp_typ, tmp, 255);
576 		Decimal("start", partp->dp_start, tmp, NO_DISK_SECTORS);
577 		Decimal("size", partp->dp_size, tmp, NO_DISK_SECTORS);
578 		if (!sanitize_partition(partp)) {
579 			warnx("ERROR: failed to adjust; setting sysid to 0");
580 			partp->dp_typ = 0;
581 		}
582 
583 		if (ok("Explicitly specify beg/end address ?"))
584 		{
585 			int	tsec,tcyl,thd;
586 			tcyl = DPCYL(partp->dp_scyl,partp->dp_ssect);
587 			thd = partp->dp_shd;
588 			tsec = DPSECT(partp->dp_ssect);
589 			Decimal("beginning cylinder", tcyl, tmp, NO_TRACK_CYLINDERS);
590 			Decimal("beginning head", thd, tmp, NO_TRACK_HEADS);
591 			Decimal("beginning sector", tsec, tmp, NO_TRACK_SECTORS);
592 			partp->dp_scyl = DOSCYL(tcyl);
593 			partp->dp_ssect = DOSSECT(tsec,tcyl);
594 			partp->dp_shd = thd;
595 
596 			tcyl = DPCYL(partp->dp_ecyl,partp->dp_esect);
597 			thd = partp->dp_ehd;
598 			tsec = DPSECT(partp->dp_esect);
599 			Decimal("ending cylinder", tcyl, tmp, NO_TRACK_CYLINDERS);
600 			Decimal("ending head", thd, tmp, NO_TRACK_HEADS);
601 			Decimal("ending sector", tsec, tmp, NO_TRACK_SECTORS);
602 			partp->dp_ecyl = DOSCYL(tcyl);
603 			partp->dp_esect = DOSSECT(tsec,tcyl);
604 			partp->dp_ehd = thd;
605 		} else
606 			dos(partp);
607 
608 		print_part(partp);
609 	} while (!ok("Are we happy with this entry?"));
610     }
611 }
612 
613 static void
614 print_params(void)
615 {
616 	printf("parameters extracted from in-core disklabel are:\n");
617 	printf("cylinders=%d heads=%d sectors/track=%d (%d blks/cyl)\n\n"
618 			,cyls,heads,sectors,cylsecs);
619 	if (dos_cyls > 1023 || dos_heads > 255 || dos_sectors > 63)
620 		printf("Figures below won't work with BIOS for partitions not in cyl 1\n");
621 	printf("parameters to be used for BIOS calculations are:\n");
622 	printf("cylinders=%d heads=%d sectors/track=%d (%d blks/cyl)\n\n"
623 		,dos_cyls,dos_heads,dos_sectors,dos_cylsecs);
624 }
625 
626 static void
627 change_active(int which)
628 {
629 	struct dos_partition *partp = &mboot.parts[0];
630 	int active, i, new, tmp;
631 
632 	active = -1;
633 	for (i = 0; i < NDOSPART; i++) {
634 		if ((partp[i].dp_flag & ACTIVE) == 0)
635 			continue;
636 		printf("Partition %d is marked active\n", i + 1);
637 		if (active == -1)
638 			active = i + 1;
639 	}
640 	if (a_flag && which != -1)
641 		active = which;
642 	else if (active == -1)
643 		active = 1;
644 
645 	if (!ok("Do you want to change the active partition?"))
646 		return;
647 setactive:
648 	do {
649 		new = active;
650 		Decimal("active partition", new, tmp, 0);
651 		if (new < 1 || new > 4) {
652 			printf("Active partition number must be in range 1-4."
653 					"  Try again.\n");
654 			goto setactive;
655 		}
656 		active = new;
657 	} while (!ok("Are you happy with this choice"));
658 	for (i = 0; i < NDOSPART; i++)
659 		partp[i].dp_flag = 0;
660 	if (active > 0 && active <= NDOSPART)
661 		partp[active-1].dp_flag = ACTIVE;
662 }
663 
664 static void
665 change_code(void)
666 {
667 	if (ok("Do you want to change the boot code?"))
668 		init_boot();
669 }
670 
671 void
672 get_params_to_use(void)
673 {
674 	int	tmp;
675 	print_params();
676 	if (ok("Do you want to change our idea of what BIOS thinks ?"))
677 	{
678 		do
679 		{
680 			Decimal("BIOS's idea of #cylinders", dos_cyls, tmp, 0);
681 			Decimal("BIOS's idea of #heads", dos_heads, tmp, 0);
682 			Decimal("BIOS's idea of #sectors", dos_sectors, tmp, 0);
683 			dos_cylsecs = dos_heads * dos_sectors;
684 			print_params();
685 		}
686 		while(!ok("Are you happy with this choice"));
687 	}
688 }
689 
690 
691 /***********************************************\
692 * Change real numbers into strange dos numbers	*
693 \***********************************************/
694 static void
695 dos(struct dos_partition *partp)
696 {
697 	int cy, sec;
698 	u_int32_t end;
699 
700 	if (partp->dp_typ == 0 && partp->dp_start == 0 && partp->dp_size == 0) {
701 		memcpy(partp, &mtpart, sizeof(*partp));
702 		return;
703 	}
704 
705 	/* Start c/h/s. */
706 	partp->dp_shd = partp->dp_start % dos_cylsecs / dos_sectors;
707 	cy = partp->dp_start / dos_cylsecs;
708 	sec = partp->dp_start % dos_sectors + 1;
709 	partp->dp_scyl = DOSCYL(cy);
710 	partp->dp_ssect = DOSSECT(sec, cy);
711 
712 	/* End c/h/s. */
713 	end = partp->dp_start + partp->dp_size - 1;
714 	partp->dp_ehd = end % dos_cylsecs / dos_sectors;
715 	cy = end / dos_cylsecs;
716 	sec = end % dos_sectors + 1;
717 	partp->dp_ecyl = DOSCYL(cy);
718 	partp->dp_esect = DOSSECT(sec, cy);
719 }
720 
721 static int
722 open_disk(int flag)
723 {
724 	int rwmode;
725 
726 	/* Write mode if one of these flags are set. */
727 	rwmode = (a_flag || I_flag || B_flag || flag);
728 	fd = g_open(disk, rwmode);
729 	/* If the mode fails, try read-only if we didn't. */
730 	if (fd == -1 && errno == EPERM && rwmode)
731 		fd = g_open(disk, 0);
732 	if (fd == -1 && errno == ENXIO)
733 		return -2;
734 	if (fd == -1) {
735 		warnx("can't open device %s", disk);
736 		return -1;
737 	}
738 	if (get_params() == -1) {
739 		warnx("can't get disk parameters on %s", disk);
740 		return -1;
741 	}
742 	return fd;
743 }
744 
745 static ssize_t
746 read_disk(off_t sector, void *buf)
747 {
748 
749 	lseek(fd, (sector * 512), 0);
750 	if (secsize == 0)
751 		for (secsize = MIN_SEC_SIZE; secsize <= MAX_SEC_SIZE;
752 		     secsize *= 2) {
753 			/* try the read */
754 			int size = read(fd, buf, secsize);
755 			if (size == secsize)
756 				/* it worked so return */
757 				return secsize;
758 		}
759 	else
760 		return read(fd, buf, secsize);
761 
762 	/* we failed to read at any of the sizes */
763 	return -1;
764 }
765 
766 static int
767 geom_class_available(const char *name)
768 {
769 	struct gclass *class;
770 	struct gmesh mesh;
771 	int error;
772 
773 	error = geom_gettree(&mesh);
774 	if (error != 0)
775 		errc(1, error, "Cannot get GEOM tree");
776 
777 	LIST_FOREACH(class, &mesh.lg_class, lg_class) {
778 		if (strcmp(class->lg_name, name) == 0) {
779 			geom_deletetree(&mesh);
780 			return (1);
781 		}
782 	}
783 
784 	geom_deletetree(&mesh);
785 
786 	return (0);
787 }
788 
789 static int
790 write_disk(off_t sector, void *buf)
791 {
792 	ssize_t wr;
793 
794 	/*
795 	 * Try to write MBR directly. This may help when disk
796 	 * is not in use.
797 	 * XXX: hardcoded sectorsize
798 	 */
799 	wr = pwrite(fd, buf, secsize, (sector * 512));
800 	if (wr == secsize)
801 		return (0);
802 
803 	if (geom_class_available("PART") != 0)
804 		warnx("Failed to write MBR. Try to use gpart(8).");
805 	else
806 		warnx("Failed to write sector zero");
807 	return(EINVAL);
808 }
809 
810 static int
811 get_params(void)
812 {
813 	int error;
814 	u_int u;
815 	off_t o;
816 
817 	error = ioctl(fd, DIOCGFWSECTORS, &u);
818 	if (error == 0)
819 		sectors = dos_sectors = u;
820 	else
821 		sectors = dos_sectors = 63;
822 
823 	error = ioctl(fd, DIOCGFWHEADS, &u);
824 	if (error == 0)
825 		heads = dos_heads = u;
826 	else
827 		heads = dos_heads = 255;
828 
829 	dos_cylsecs = cylsecs = heads * sectors;
830 	disksecs = cyls * heads * sectors;
831 
832 	u = g_sectorsize(fd);
833 	if (u <= 0)
834 		return (-1);
835 
836 	o = g_mediasize(fd);
837 	if (o < 0)
838 		return (-1);
839 	if (o / u <= NO_DISK_SECTORS)
840 		disksecs = o / u;
841 	else
842 		disksecs = NO_DISK_SECTORS;
843 	cyls = dos_cyls = o / (u * dos_heads * dos_sectors);
844 
845 	return (0);
846 }
847 
848 static int
849 read_s0(void)
850 {
851 	int i;
852 
853 	mboot.bootinst_size = secsize;
854 	if (mboot.bootinst != NULL)
855 		free(mboot.bootinst);
856 	if ((mboot.bootinst = malloc(mboot.bootinst_size)) == NULL) {
857 		warnx("unable to allocate buffer to read fdisk "
858 		      "partition table");
859 		return -1;
860 	}
861 	if (read_disk(0, mboot.bootinst) == -1) {
862 		warnx("can't read fdisk partition table");
863 		return -1;
864 	}
865 	if (le16dec(&mboot.bootinst[DOSMAGICOFFSET]) != DOSMAGIC) {
866 		warnx("invalid fdisk partition table found");
867 		/* So should we initialize things */
868 		return -1;
869 	}
870 	for (i = 0; i < NDOSPART; i++)
871 		dos_partition_dec(
872 		    &mboot.bootinst[DOSPARTOFF + i * DOSPARTSIZE],
873 		    &mboot.parts[i]);
874 	return 0;
875 }
876 
877 static int
878 write_s0(void)
879 {
880 	int	sector, i;
881 
882 	if (iotest) {
883 		print_s0();
884 		return 0;
885 	}
886 	for(i = 0; i < NDOSPART; i++)
887 		dos_partition_enc(&mboot.bootinst[DOSPARTOFF + i * DOSPARTSIZE],
888 		    &mboot.parts[i]);
889 	le16enc(&mboot.bootinst[DOSMAGICOFFSET], DOSMAGIC);
890 	for(sector = 0; sector < mboot.bootinst_size / secsize; sector++)
891 		if (write_disk(sector,
892 			       &mboot.bootinst[sector * secsize]) == -1) {
893 			warn("can't write fdisk partition table");
894 			return -1;
895 		}
896 	return(0);
897 }
898 
899 
900 static int
901 ok(const char *str)
902 {
903 	printf("%s [n] ", str);
904 	fflush(stdout);
905 	if (fgets(lbuf, LBUF, stdin) == NULL)
906 		exit(1);
907 	lbuf[strlen(lbuf)-1] = 0;
908 
909 	if (*lbuf &&
910 		(!strcmp(lbuf, "yes") || !strcmp(lbuf, "YES") ||
911 		 !strcmp(lbuf, "y") || !strcmp(lbuf, "Y")))
912 		return 1;
913 	else
914 		return 0;
915 }
916 
917 static int
918 decimal(const char *str, int *num, int deflt, uint32_t maxval)
919 {
920 	long long acc;
921 	int c;
922 	char *cp;
923 
924 	while (1) {
925 		acc = 0;
926 		printf("Supply a decimal value for \"%s\" [%d] ", str, deflt);
927 		fflush(stdout);
928 		if (fgets(lbuf, LBUF, stdin) == NULL)
929 			exit(1);
930 		lbuf[strlen(lbuf)-1] = 0;
931 
932 		if (!*lbuf)
933 			return 0;
934 
935 		cp = lbuf;
936 		while ((c = *cp) && (c == ' ' || c == '\t')) cp++;
937 		if (!c)
938 			return 0;
939 		while ((c = *cp++)) {
940 			if (c <= '9' && c >= '0') {
941 				if (acc <= maxval || maxval == 0)
942 					acc = acc * 10 + c - '0';
943 			} else
944 				break;
945 		}
946 		if (c == ' ' || c == '\t')
947 			while ((c = *cp) && (c == ' ' || c == '\t')) cp++;
948 		if (!c) {
949 			if (maxval > 0 && acc > maxval) {
950 				acc = maxval;
951 				printf("%s exceeds maximum value allowed for "
952 				  "this field. The value has been reduced "
953 				  "to %lld\n", lbuf, acc);
954 			}
955 			*num = acc;
956 			return 1;
957 		} else
958 			printf("%s is an invalid decimal number.  Try again.\n",
959 				lbuf);
960 	}
961 }
962 
963 
964 static void
965 parse_config_line(char *line, CMD *command)
966 {
967     char	*cp, *end;
968 
969     cp = line;
970     while (1) {
971 	memset(command, 0, sizeof(*command));
972 
973 	while (isspace(*cp)) ++cp;
974 	if (*cp == '\0' || *cp == '#')
975 	    break;
976 	command->cmd = *cp++;
977 
978 	/*
979 	 * Parse args
980 	 */
981 	    while (1) {
982 	    while (isspace(*cp)) ++cp;
983 	    if (*cp == '\0')
984 		break;		/* eol */
985 	    if (*cp == '#')
986 		break;		/* found comment */
987 	    if (isalpha(*cp))
988 		command->args[command->n_args].argtype = *cp++;
989 	    end = NULL;
990 	    command->args[command->n_args].arg_val = strtoul(cp, &end, 0);
991  	    if (cp == end || (!isspace(*end) && *end != '\0')) {
992  		char ch;
993  		end = cp;
994  		while (!isspace(*end) && *end != '\0') ++end;
995  		ch = *end; *end = '\0';
996  		command->args[command->n_args].arg_str = strdup(cp);
997  		*end = ch;
998  	    } else
999  		command->args[command->n_args].arg_str = NULL;
1000 	    cp = end;
1001 	    command->n_args++;
1002 	}
1003 	break;
1004     }
1005 }
1006 
1007 
1008 static int
1009 process_geometry(CMD *command)
1010 {
1011     int		status = 1, i;
1012 
1013     while (1) {
1014 	geom_processed = 1;
1015 	    if (part_processed) {
1016 	    warnx(
1017 	"ERROR line %d: the geometry specification line must occur before\n\
1018     all partition specifications",
1019 		    current_line_number);
1020 	    status = 0;
1021 	    break;
1022 	}
1023 	    if (command->n_args != 3) {
1024 	    warnx("ERROR line %d: incorrect number of geometry args",
1025 		    current_line_number);
1026 	    status = 0;
1027 	    break;
1028 	}
1029 	    dos_cyls = 0;
1030 	    dos_heads = 0;
1031 	    dos_sectors = 0;
1032 	    for (i = 0; i < 3; ++i) {
1033 		    switch (command->args[i].argtype) {
1034 	    case 'c':
1035 		dos_cyls = command->args[i].arg_val;
1036 		break;
1037 	    case 'h':
1038 		dos_heads = command->args[i].arg_val;
1039 		break;
1040 	    case 's':
1041 		dos_sectors = command->args[i].arg_val;
1042 		break;
1043 	    default:
1044 		warnx(
1045 		"ERROR line %d: unknown geometry arg type: '%c' (0x%02x)",
1046 			current_line_number, command->args[i].argtype,
1047 			command->args[i].argtype);
1048 		status = 0;
1049 		break;
1050 	    }
1051 	}
1052 	if (status == 0)
1053 	    break;
1054 
1055 	dos_cylsecs = dos_heads * dos_sectors;
1056 
1057 	/*
1058 	 * Do sanity checks on parameter values
1059 	 */
1060 	    if (dos_cyls == 0) {
1061 	    warnx("ERROR line %d: number of cylinders not specified",
1062 		    current_line_number);
1063 	    status = 0;
1064 	}
1065 	    if (dos_cyls > 1024) {
1066 	    warnx(
1067 	"WARNING line %d: number of cylinders (%d) may be out-of-range\n\
1068     (must be within 1-1024 for normal BIOS operation, unless the entire disk\n\
1069     is dedicated to FreeBSD)",
1070 		    current_line_number, dos_cyls);
1071 	}
1072 
1073 	    if (dos_heads == 0) {
1074 	    warnx("ERROR line %d: number of heads not specified",
1075 		    current_line_number);
1076 	    status = 0;
1077 	    } else if (dos_heads > 256) {
1078 	    warnx("ERROR line %d: number of heads must be within (1-256)",
1079 		    current_line_number);
1080 	    status = 0;
1081 	}
1082 
1083 	    if (dos_sectors == 0) {
1084 	    warnx("ERROR line %d: number of sectors not specified",
1085 		    current_line_number);
1086 	    status = 0;
1087 	    } else if (dos_sectors > 63) {
1088 	    warnx("ERROR line %d: number of sectors must be within (1-63)",
1089 		    current_line_number);
1090 	    status = 0;
1091 	}
1092 
1093 	break;
1094     }
1095     return (status);
1096 }
1097 
1098 static u_int32_t
1099 str2sectors(const char *str)
1100 {
1101 	char *end;
1102 	unsigned long val;
1103 
1104 	val = strtoul(str, &end, 0);
1105 	if (str == end || *end == '\0') {
1106 		warnx("ERROR line %d: unexpected size: \'%s\'",
1107 		    current_line_number, str);
1108 		return NO_DISK_SECTORS;
1109 	}
1110 
1111 	if (*end == 'K')
1112 		val *= 1024UL / secsize;
1113 	else if (*end == 'M')
1114 		val *= 1024UL * 1024UL / secsize;
1115 	else if (*end == 'G')
1116 		val *= 1024UL * 1024UL * 1024UL / secsize;
1117 	else {
1118 		warnx("ERROR line %d: unexpected modifier: %c "
1119 		    "(not K/M/G)", current_line_number, *end);
1120 		return NO_DISK_SECTORS;
1121 	}
1122 
1123 	return val;
1124 }
1125 
1126 static int
1127 process_partition(CMD *command)
1128 {
1129     int				status = 0, partition;
1130     u_int32_t			prev_head_boundary, prev_cyl_boundary;
1131     u_int32_t			adj_size, max_end;
1132     struct dos_partition	*partp;
1133 
1134 	while (1) {
1135 	part_processed = 1;
1136 		if (command->n_args != 4) {
1137 	    warnx("ERROR line %d: incorrect number of partition args",
1138 		    current_line_number);
1139 	    break;
1140 	}
1141 	partition = command->args[0].arg_val;
1142 		if (partition < 1 || partition > 4) {
1143 	    warnx("ERROR line %d: invalid partition number %d",
1144 		    current_line_number, partition);
1145 	    break;
1146 	}
1147 	partp = &mboot.parts[partition - 1];
1148 	bzero(partp, sizeof (*partp));
1149 	partp->dp_typ = command->args[1].arg_val;
1150 	if (command->args[2].arg_str != NULL) {
1151 		if (strcmp(command->args[2].arg_str, "*") == 0) {
1152 			int i;
1153 			partp->dp_start = dos_sectors;
1154 			for (i = 1; i < partition; i++) {
1155     				struct dos_partition *prev_partp;
1156 				prev_partp = ((struct dos_partition *)
1157 				    &mboot.parts) + i - 1;
1158 				if (prev_partp->dp_typ != 0)
1159 					partp->dp_start = prev_partp->dp_start +
1160 					    prev_partp->dp_size;
1161 			}
1162 			if (partp->dp_start % dos_sectors != 0) {
1163 				prev_head_boundary = rounddown(partp->dp_start,
1164 				    dos_sectors);
1165 		    		partp->dp_start = prev_head_boundary +
1166 				    dos_sectors;
1167 			}
1168 		} else {
1169 			partp->dp_start = str2sectors(command->args[2].arg_str);
1170 			if (partp->dp_start == NO_DISK_SECTORS)
1171 				break;
1172 		}
1173 	} else
1174 		partp->dp_start = command->args[2].arg_val;
1175 
1176 	if (command->args[3].arg_str != NULL) {
1177 		if (strcmp(command->args[3].arg_str, "*") == 0)
1178 			partp->dp_size = rounddown(disksecs, dos_cylsecs) -
1179 			    partp->dp_start;
1180 		else {
1181 			partp->dp_size = str2sectors(command->args[3].arg_str);
1182 			if (partp->dp_size == NO_DISK_SECTORS)
1183 				break;
1184 		}
1185 		prev_cyl_boundary = rounddown(partp->dp_start + partp->dp_size,
1186 		    dos_cylsecs);
1187 		if (prev_cyl_boundary > partp->dp_start)
1188 			partp->dp_size = prev_cyl_boundary - partp->dp_start;
1189 	} else
1190 		partp->dp_size = command->args[3].arg_val;
1191 
1192 	max_end = partp->dp_start + partp->dp_size;
1193 
1194 	if (partp->dp_typ == 0) {
1195 	    /*
1196 	     * Get out, the partition is marked as unused.
1197 	     */
1198 	    /*
1199 	     * Insure that it's unused.
1200 	     */
1201 	    bzero(partp, sizeof(*partp));
1202 	    status = 1;
1203 	    break;
1204 	}
1205 
1206 	/*
1207 	 * Adjust start upwards, if necessary, to fall on a head boundary.
1208 	 */
1209 		if (partp->dp_start % dos_sectors != 0) {
1210 	    prev_head_boundary = rounddown(partp->dp_start, dos_sectors);
1211 	    if (max_end < dos_sectors ||
1212 			    prev_head_boundary > max_end - dos_sectors) {
1213 		/*
1214 		 * Can't go past end of partition
1215 		 */
1216 		warnx(
1217 	"ERROR line %d: unable to adjust start of partition %d to fall on\n\
1218     a head boundary",
1219 			current_line_number, partition);
1220 		break;
1221 	    }
1222 	    warnx(
1223 	"WARNING: adjusting start offset of partition %d\n\
1224     from %u to %u, to fall on a head boundary",
1225 		    partition, (u_int)partp->dp_start,
1226 		    (u_int)(prev_head_boundary + dos_sectors));
1227 	    partp->dp_start = prev_head_boundary + dos_sectors;
1228 	}
1229 
1230 	/*
1231 	 * Adjust size downwards, if necessary, to fall on a cylinder
1232 	 * boundary.
1233 	 */
1234 	prev_cyl_boundary = rounddown(partp->dp_start + partp->dp_size,
1235 	    dos_cylsecs);
1236 	if (prev_cyl_boundary > partp->dp_start)
1237 	    adj_size = prev_cyl_boundary - partp->dp_start;
1238 		else {
1239 	    warnx(
1240 	"ERROR: could not adjust partition to start on a head boundary\n\
1241     and end on a cylinder boundary.");
1242 	    return (0);
1243 	}
1244 		if (adj_size != partp->dp_size) {
1245 	    warnx(
1246 	"WARNING: adjusting size of partition %d from %u to %u\n\
1247     to end on a cylinder boundary",
1248 		    partition, (u_int)partp->dp_size, (u_int)adj_size);
1249 	    partp->dp_size = adj_size;
1250 	}
1251 		if (partp->dp_size == 0) {
1252 	    warnx("ERROR line %d: size of partition %d is zero",
1253 		    current_line_number, partition);
1254 	    break;
1255 	}
1256 
1257 	dos(partp);
1258 	status = 1;
1259 	break;
1260     }
1261     return (status);
1262 }
1263 
1264 
1265 static int
1266 process_active(CMD *command)
1267 {
1268     int				status = 0, partition, i;
1269     struct dos_partition	*partp;
1270 
1271 	while (1) {
1272 	active_processed = 1;
1273 		if (command->n_args != 1) {
1274 	    warnx("ERROR line %d: incorrect number of active args",
1275 		    current_line_number);
1276 	    status = 0;
1277 	    break;
1278 	}
1279 	partition = command->args[0].arg_val;
1280 		if (partition < 1 || partition > 4) {
1281 	    warnx("ERROR line %d: invalid partition number %d",
1282 		    current_line_number, partition);
1283 	    break;
1284 	}
1285 	/*
1286 	 * Reset active partition
1287 	 */
1288 	partp = mboot.parts;
1289 	for (i = 0; i < NDOSPART; i++)
1290 	    partp[i].dp_flag = 0;
1291 	partp[partition-1].dp_flag = ACTIVE;
1292 
1293 	status = 1;
1294 	break;
1295     }
1296     return (status);
1297 }
1298 
1299 
1300 static int
1301 process_line(char *line)
1302 {
1303     CMD		command;
1304     int		status = 1;
1305 
1306 	while (1) {
1307 	parse_config_line(line, &command);
1308 		switch (command.cmd) {
1309 	case 0:
1310 	    /*
1311 	     * Comment or blank line
1312 	     */
1313 	    break;
1314 	case 'g':
1315 	    /*
1316 	     * Set geometry
1317 	     */
1318 	    status = process_geometry(&command);
1319 	    break;
1320 	case 'p':
1321 	    status = process_partition(&command);
1322 	    break;
1323 	case 'a':
1324 	    status = process_active(&command);
1325 	    break;
1326 	default:
1327 	    status = 0;
1328 	    break;
1329 	}
1330 	break;
1331     }
1332     return (status);
1333 }
1334 
1335 
1336 static int
1337 read_config(char *config_file)
1338 {
1339     FILE	*fp = NULL;
1340     int		status = 1;
1341     char	buf[1010];
1342 
1343 	while (1) {
1344 		if (strcmp(config_file, "-") != 0) {
1345 	    /*
1346 	     * We're not reading from stdin
1347 	     */
1348 			if ((fp = fopen(config_file, "r")) == NULL) {
1349 		status = 0;
1350 		break;
1351 	    }
1352 		} else {
1353 	    fp = stdin;
1354 	}
1355 	current_line_number = 0;
1356 		while (!feof(fp)) {
1357 	    if (fgets(buf, sizeof(buf), fp) == NULL)
1358 		break;
1359 	    ++current_line_number;
1360 	    status = process_line(buf);
1361 	    if (status == 0)
1362 		break;
1363 	    }
1364 	break;
1365     }
1366 	if (fp) {
1367 	/*
1368 	 * It doesn't matter if we're reading from stdin, as we've reached EOF
1369 	 */
1370 	fclose(fp);
1371     }
1372     return (status);
1373 }
1374 
1375 
1376 static void
1377 reset_boot(void)
1378 {
1379     int				i;
1380     struct dos_partition	*partp;
1381 
1382     init_boot();
1383     for (i = 0; i < 4; ++i) {
1384 	partp = &mboot.parts[i];
1385 	bzero(partp, sizeof(*partp));
1386     }
1387 }
1388 
1389 static int
1390 sanitize_partition(struct dos_partition *partp)
1391 {
1392     u_int32_t			prev_head_boundary, prev_cyl_boundary;
1393     u_int32_t			max_end, size, start;
1394 
1395     start = partp->dp_start;
1396     size = partp->dp_size;
1397     max_end = start + size;
1398     /* Only allow a zero size if the partition is being marked unused. */
1399     if (size == 0) {
1400 	if (start == 0 && partp->dp_typ == 0)
1401 	    return (1);
1402 	warnx("ERROR: size of partition is zero");
1403 	return (0);
1404     }
1405     /* Return if no adjustment is necessary. */
1406     if (start % dos_sectors == 0 && (start + size) % dos_sectors == 0)
1407 	return (1);
1408 
1409     if (start == 0) {
1410 	    warnx("WARNING: partition overlaps with partition table");
1411 	    if (ok("Correct this automatically?"))
1412 		    start = dos_sectors;
1413     }
1414     if (start % dos_sectors != 0)
1415 	warnx("WARNING: partition does not start on a head boundary");
1416     if ((start  +size) % dos_sectors != 0)
1417 	warnx("WARNING: partition does not end on a cylinder boundary");
1418     warnx("WARNING: this may confuse the BIOS or some operating systems");
1419     if (!ok("Correct this automatically?"))
1420 	return (1);
1421 
1422     /*
1423      * Adjust start upwards, if necessary, to fall on a head boundary.
1424      */
1425     if (start % dos_sectors != 0) {
1426 	prev_head_boundary = rounddown(start, dos_sectors);
1427 	if (max_end < dos_sectors ||
1428 	    prev_head_boundary >= max_end - dos_sectors) {
1429 	    /*
1430 	     * Can't go past end of partition
1431 	     */
1432 	    warnx(
1433     "ERROR: unable to adjust start of partition to fall on a head boundary");
1434 	    return (0);
1435         }
1436 	start = prev_head_boundary + dos_sectors;
1437     }
1438 
1439     /*
1440      * Adjust size downwards, if necessary, to fall on a cylinder
1441      * boundary.
1442      */
1443     prev_cyl_boundary = rounddown(start + size, dos_cylsecs);
1444     if (prev_cyl_boundary > start)
1445 	size = prev_cyl_boundary - start;
1446     else {
1447 	warnx("ERROR: could not adjust partition to start on a head boundary\n\
1448     and end on a cylinder boundary.");
1449 	return (0);
1450     }
1451 
1452     /* Finally, commit any changes to partp and return. */
1453     if (start != partp->dp_start) {
1454 	warnx("WARNING: adjusting start offset of partition to %u",
1455 	    (u_int)start);
1456 	partp->dp_start = start;
1457     }
1458     if (size != partp->dp_size) {
1459 	warnx("WARNING: adjusting size of partition to %u", (u_int)size);
1460 	partp->dp_size = size;
1461     }
1462 
1463     return (1);
1464 }
1465 
1466 /*
1467  * Try figuring out the root device's canonical disk name.
1468  * The following choices are considered:
1469  *   /dev/ad0s1a     => /dev/ad0
1470  *   /dev/da0a       => /dev/da0
1471  *   /dev/vinum/root => /dev/vinum/root
1472  * A ".eli" part is removed if it exists (see geli(8)).
1473  * A ".journal" ending is removed if it exists (see gjournal(8)).
1474  */
1475 static char *
1476 get_rootdisk(void)
1477 {
1478 	struct statfs rootfs;
1479 	regex_t re;
1480 #define NMATCHES 2
1481 	regmatch_t rm[NMATCHES];
1482 	char dev[PATH_MAX], *s;
1483 	int rv;
1484 
1485 	if (statfs("/", &rootfs) == -1)
1486 		err(1, "statfs(\"/\")");
1487 
1488 	if ((rv = regcomp(&re, "^(/dev/[a-z/]+[0-9]*)([sp][0-9]+)?[a-h]?(\\.journal)?$",
1489 		    REG_EXTENDED)) != 0)
1490 		errx(1, "regcomp() failed (%d)", rv);
1491 	strlcpy(dev, rootfs.f_mntfromname, sizeof (dev));
1492 	if ((s = strstr(dev, ".eli")) != NULL)
1493 	    memmove(s, s+4, strlen(s + 4) + 1);
1494 
1495 	if ((rv = regexec(&re, dev, NMATCHES, rm, 0)) != 0)
1496 		errx(1,
1497 "mounted root fs resource doesn't match expectations (regexec returned %d)",
1498 		    rv);
1499 	if ((s = malloc(rm[1].rm_eo - rm[1].rm_so + 1)) == NULL)
1500 		errx(1, "out of memory");
1501 	memcpy(s, rootfs.f_mntfromname + rm[1].rm_so,
1502 	    rm[1].rm_eo - rm[1].rm_so);
1503 	s[rm[1].rm_eo - rm[1].rm_so] = 0;
1504 
1505 	return s;
1506 }
1507