xref: /titanic_41/usr/src/cmd/fs.d/pcfs/fsck/pcfs_common.c (revision 986fd29a0dc13f7608ef7f508f6e700bd7bc2720)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 /*
23  * Copyright (c) 1999,2001 by Sun Microsystems, Inc.
24  * All rights reserved.
25  */
26 
27 #pragma ident	"%Z%%M%	%I%	%E% SMI"
28 
29 /*
30  * fsck_pcfs -- common.c
31  *	All the routines in this file are being swiped directly from
32  *	mkfs_pcfs.  Eventually this file should only exist in one place
33  *	and be part of a library that both mkfs and fsck link against.
34  */
35 #include <stdio.h>
36 #include <string.h>
37 #include <unistd.h>
38 #include <stdlib.h>
39 #include <libintl.h>
40 #include <sys/isa_defs.h>
41 #include <sys/types.h>
42 #include <sys/stat.h>
43 #include <sys/fcntl.h>
44 #include <sys/dktp/fdisk.h>
45 #include <sys/fs/pc_fs.h>
46 #include <sys/fs/pc_dir.h>
47 #include <sys/fs/pc_label.h>
48 #include "fsck_pcfs.h"
49 #include "pcfs_common.h"
50 #include "pcfs_bpb.h"
51 
52 /*
53  *	The assumption here is that _BIG_ENDIAN implies sparc, and
54  *	so in addition to swapping bytes we also have to construct
55  *	packed structures by hand to avoid bus errors due to improperly
56  *	aligned pointers.
57  */
58 #ifdef _BIG_ENDIAN
59 void swap_pack_grab32bpb(bpb_t *wbpb, struct _boot_sector *bsp);
60 void swap_pack_grabbpb(bpb_t *wbpb, struct _boot_sector *bsp);
61 #endif /* _BIG_ENDIAN */
62 
63 /*
64  *  Global variables related to input questions
65  */
66 extern int AlwaysYes;
67 extern int AlwaysNo;
68 
69 int
70 is_z_a_power_of_x_le_y(int x, int y, int z)
71 {
72 	int ispower = 0;
73 	int pow = 1;
74 
75 	do {
76 		if (pow == z) {
77 			ispower = 1;
78 			break;
79 		}
80 		pow *= x;
81 	} while (pow <= y);
82 
83 	return (ispower);
84 }
85 
86 /*
87  * store_16_bits
88  *	Save the lower 16 bits of a 32 bit value (v) into the provided
89  *	buffer (pointed at by *bp), and increment the buffer pointer
90  *	as well.  This way the routine can be called multiple times in
91  *	succession to fill buffers.  The value is stored in little-endian
92  *	order.
93  */
94 void
95 store_16_bits(uchar_t **bp, uint32_t v)
96 {
97 	uchar_t *l = *bp;
98 
99 	*l++ = v & 0xff;
100 	*l = (v >> 8) & 0xff;
101 	*bp += 2;
102 }
103 
104 void
105 read_16_bits(uchar_t *bp, uint32_t *value)
106 {
107 	*value = *bp++;
108 	*value += *bp << 8;
109 }
110 
111 /*
112  * store_32_bits
113  * 	Save the 32 bit value (v) into the provided buffer (pointed
114  *	at by *bp), and increment the buffer pointer as well.  This way
115  *	the routine can be called multiple times in succession to fill
116  *	buffers.  The value is stored in little-endian order.
117  */
118 void
119 store_32_bits(uchar_t **bp, uint32_t v)
120 {
121 	uchar_t *l = *bp;
122 	int b;
123 
124 	for (b = 0; b < 4; b++) {
125 		*l++ = v & 0xff;
126 		v = v >> 8;
127 	}
128 	*bp += 4;
129 }
130 
131 void
132 read_32_bits(uchar_t *bp, uint32_t *value)
133 {
134 	*value = *bp++;
135 	*value += *bp++ << 8;
136 	*value += *bp++ << 16;
137 	*value += *bp++ << 24;
138 }
139 
140 /*
141  *  dump_bytes  -- display bytes as hex numbers.
142  *		   b is the pointer to the byte buffer
143  *		   n is the number of bytes in the buffer
144  */
145 /* Note: BPL = bytes to display per line */
146 #define	BPL 16
147 
148 void
149 dump_bytes(uchar_t *buf, int n)
150 {
151 	int printedCount;
152 	int countdown = n;
153 	int countup = 0;
154 	int offset = 0;
155 	int byte;
156 
157 	/* Display offset, 16 bytes per line, and printable ascii version */
158 	while (countdown > 0) {
159 		printedCount = 0;
160 		(void) fprintf(stderr, "\n%06x: ", offset);
161 		/*
162 		 * Print Hex value of characters in columns on left
163 		 */
164 		for (byte = 0; byte < BPL; byte++) {
165 			if (countup + byte < n) {
166 				(void) fprintf(stderr,
167 				    "%02x ", (buf[countup + byte] & 0xff));
168 				printedCount++;
169 			} else {
170 				(void) fprintf(stderr, "   ");
171 			}
172 		}
173 		/*
174 		 * Right side has the printable character or '.' for
175 		 * unprintable for each column of the left.
176 		 */
177 		for (byte = 0; byte < BPL; byte++) {
178 			if ((countup + byte < n) &&
179 			    ((buf[countup + byte] >= ' ') &&
180 			    (buf[countup + byte] <= '~'))) {
181 				(void) fprintf(stderr, "%c",
182 				    buf[countup + byte]);
183 			} else {
184 				(void) fprintf(stderr, ".");
185 			}
186 		}
187 		countup += printedCount;
188 		offset += printedCount;
189 		countdown -= printedCount;
190 	}
191 	(void) fprintf(stderr, "\n\n");
192 }
193 
194 /*
195  *  header_for_dump  --  display simple header over what will be output.
196  */
197 void
198 header_for_dump(void)
199 {
200 	int byte;
201 
202 	(void) fprintf(stderr, "\n        ");
203 	for (byte = 0; byte < BPL; byte++)
204 		(void) fprintf(stderr, "%02x ", byte);
205 	(void) fprintf(stderr, "\n       ");
206 	byte = 3*BPL;
207 	while (byte-- > 0)
208 		(void) fprintf(stderr, "-");
209 }
210 
211 /*
212  *  We are basically (incorrectly) assuming that if you aren't running
213  *  on x86 the BPB has to be packed by hand AND that the bytes must
214  *  be swapped.  One or both of these assumptions may one day be invalid.
215  *  (if they aren't already :-))
216  */
217 #ifdef _BIG_ENDIAN
218 /*
219  *  swap_pack_grab{32}bpb
220  *	If not on an x86 we assume the structures making up the bpb
221  *	were not packed and that longs and shorts need to be byte swapped
222  *	(we've kept everything in host order up until now).  A new architecture
223  *	might not need to swap or might not need to pack, in which case
224  *	new routines will have to be written.  Of course if an architecture
225  *	supports both packing and little-endian host order, it can follow the
226  *	same path as the x86 code.
227  */
228 void
229 swap_pack_grabbpb(bpb_t *wbpb, struct _boot_sector *bsp)
230 {
231 	uchar_t *grabp;
232 
233 	grabp = (uchar_t *)&(bsp->bs_filler[ORIG_BPB_START_INDEX]);
234 
235 	((uchar_t *)&(wbpb->bpb.bytes_per_sector))[1] = *grabp++;
236 	((uchar_t *)&(wbpb->bpb.bytes_per_sector))[0] = *grabp++;
237 	wbpb->bpb.sectors_per_cluster = *grabp++;
238 	((uchar_t *)&(wbpb->bpb.resv_sectors))[1] = *grabp++;
239 	((uchar_t *)&(wbpb->bpb.resv_sectors))[0] = *grabp++;
240 	wbpb->bpb.num_fats = *grabp++;
241 	((uchar_t *)&(wbpb->bpb.num_root_entries))[1] = *grabp++;
242 	((uchar_t *)&(wbpb->bpb.num_root_entries))[0] = *grabp++;
243 	((uchar_t *)&(wbpb->bpb.sectors_in_volume))[1] = *grabp++;
244 	((uchar_t *)&(wbpb->bpb.sectors_in_volume))[0] = *grabp++;
245 	wbpb->bpb.media = *grabp++;
246 	((uchar_t *)&(wbpb->bpb.sectors_per_fat))[1] = *grabp++;
247 	((uchar_t *)&(wbpb->bpb.sectors_per_fat))[0] = *grabp++;
248 	((uchar_t *)&(wbpb->bpb.sectors_per_track))[1] = *grabp++;
249 	((uchar_t *)&(wbpb->bpb.sectors_per_track))[0] = *grabp++;
250 	((uchar_t *)&(wbpb->bpb.heads))[1] = *grabp++;
251 	((uchar_t *)&(wbpb->bpb.heads))[0] = *grabp++;
252 	((uchar_t *)&(wbpb->bpb.hidden_sectors))[3] = *grabp++;
253 	((uchar_t *)&(wbpb->bpb.hidden_sectors))[2] = *grabp++;
254 	((uchar_t *)&(wbpb->bpb.hidden_sectors))[1] = *grabp++;
255 	((uchar_t *)&(wbpb->bpb.hidden_sectors))[0] = *grabp++;
256 	((uchar_t *)&(wbpb->bpb.sectors_in_logical_volume))[3] = *grabp++;
257 	((uchar_t *)&(wbpb->bpb.sectors_in_logical_volume))[2] = *grabp++;
258 	((uchar_t *)&(wbpb->bpb.sectors_in_logical_volume))[1] = *grabp++;
259 	((uchar_t *)&(wbpb->bpb.sectors_in_logical_volume))[0] = *grabp++;
260 	wbpb->ebpb.phys_drive_num = *grabp++;
261 	wbpb->ebpb.reserved = *grabp++;
262 	wbpb->ebpb.ext_signature = *grabp++;
263 	((uchar_t *)&(wbpb->ebpb.volume_id))[3] = *grabp++;
264 	((uchar_t *)&(wbpb->ebpb.volume_id))[2] = *grabp++;
265 	((uchar_t *)&(wbpb->ebpb.volume_id))[1] = *grabp++;
266 	((uchar_t *)&(wbpb->ebpb.volume_id))[0] = *grabp++;
267 
268 	(void) strncpy((char *)wbpb->ebpb.volume_label, (char *)grabp, 11);
269 	grabp += 11;
270 	(void) strncpy((char *)wbpb->ebpb.type, (char *)grabp, 8);
271 }
272 
273 void
274 swap_pack_grab32bpb(bpb_t *wbpb, struct _boot_sector *bsp)
275 {
276 	uchar_t *grabp;
277 
278 	grabp = (uchar_t *)&(bsp->bs_filler[BPB_32_START_INDEX]);
279 
280 	((uchar_t *)&(wbpb->bpb32.big_sectors_per_fat))[3] = *grabp++;
281 	((uchar_t *)&(wbpb->bpb32.big_sectors_per_fat))[2] = *grabp++;
282 	((uchar_t *)&(wbpb->bpb32.big_sectors_per_fat))[1] = *grabp++;
283 	((uchar_t *)&(wbpb->bpb32.big_sectors_per_fat))[0] = *grabp++;
284 	((uchar_t *)&(wbpb->bpb32.ext_flags))[1] = *grabp++;
285 	((uchar_t *)&(wbpb->bpb32.ext_flags))[0] = *grabp++;
286 	wbpb->bpb32.fs_vers_lo = *grabp++;
287 	wbpb->bpb32.fs_vers_hi = *grabp++;
288 	((uchar_t *)&(wbpb->bpb32.root_dir_clust))[3] = *grabp++;
289 	((uchar_t *)&(wbpb->bpb32.root_dir_clust))[2] = *grabp++;
290 	((uchar_t *)&(wbpb->bpb32.root_dir_clust))[1] = *grabp++;
291 	((uchar_t *)&(wbpb->bpb32.root_dir_clust))[0] = *grabp++;
292 	((uchar_t *)&(wbpb->bpb32.fsinfosec))[1] = *grabp++;
293 	((uchar_t *)&(wbpb->bpb32.fsinfosec))[0] = *grabp++;
294 	((uchar_t *)&(wbpb->bpb32.backupboot))[1] = *grabp++;
295 	((uchar_t *)&(wbpb->bpb32.backupboot))[0] = *grabp++;
296 	((uchar_t *)&(wbpb->bpb32.reserved[0]))[1] = *grabp++;
297 	((uchar_t *)&(wbpb->bpb32.reserved[0]))[0] = *grabp++;
298 	((uchar_t *)&(wbpb->bpb32.reserved[1]))[1] = *grabp++;
299 	((uchar_t *)&(wbpb->bpb32.reserved[1]))[0] = *grabp++;
300 	((uchar_t *)&(wbpb->bpb32.reserved[2]))[1] = *grabp++;
301 	((uchar_t *)&(wbpb->bpb32.reserved[2]))[0] = *grabp++;
302 	((uchar_t *)&(wbpb->bpb32.reserved[3]))[1] = *grabp++;
303 	((uchar_t *)&(wbpb->bpb32.reserved[3]))[0] = *grabp++;
304 	((uchar_t *)&(wbpb->bpb32.reserved[4]))[1] = *grabp++;
305 	((uchar_t *)&(wbpb->bpb32.reserved[4]))[0] = *grabp++;
306 	((uchar_t *)&(wbpb->bpb32.reserved[5]))[1] = *grabp++;
307 	((uchar_t *)&(wbpb->bpb32.reserved[5]))[0] = *grabp++;
308 }
309 #endif	/* _BIG_ENDIAN */
310 
311 int
312 yes(void)
313 {
314 	char *affirmative = gettext("yY");
315 	char *a = affirmative;
316 	char input[80];
317 
318 	if (AlwaysYes) {
319 		(void) printf("y\n");
320 		return (1);
321 	} else if (AlwaysNo) {
322 		(void) printf("n\n");
323 		return (0);
324 	}
325 	if (fgets(input, sizeof (input), stdin) == NULL) {
326 		AlwaysNo = 1;
327 		(void) printf("n\n");
328 		return (0);
329 	}
330 	while (*a) {
331 		if (input[0] == (int)*a)
332 			break;
333 		a++;
334 	}
335 	return ((int)*a);
336 }
337 
338 char *
339 stat_actual_disk(char *diskname, struct stat *info, char **suffix)
340 {
341 	char *actualdisk;
342 
343 	if (stat(diskname, info)) {
344 		/*
345 		 *  Device named on command line doesn't exist.  That
346 		 *  probably means there is a partition-specifying
347 		 *  suffix attached to the actual disk name.
348 		 */
349 		if ((actualdisk = strdup(diskname)) == NULL) {
350 			(void) fprintf(stderr,
351 			    gettext("Out of memory for disk name.\n"));
352 			exit(2);
353 		}
354 		if ((*suffix = strchr(actualdisk, ':')) != NULL) {
355 			**suffix = '\0';
356 			(*suffix)++;
357 		}
358 
359 		if (stat(actualdisk, info)) {
360 			perror(actualdisk);
361 			exit(2);
362 		}
363 	} else {
364 		if ((actualdisk = strdup(diskname)) == NULL) {
365 			(void) fprintf(stderr,
366 			    gettext("Out of memory for disk name.\n"));
367 			exit(2);
368 		}
369 	}
370 
371 	return (actualdisk);
372 }
373 
374 extern void usage(void);
375 
376 void
377 bad_arg(char *option)
378 {
379 	(void) fprintf(stderr,
380 		gettext("Unrecognized option -o %s.\n"), option);
381 	usage();
382 	exit(2);
383 }
384 
385 void
386 missing_arg(char *option)
387 {
388 	(void) fprintf(stderr,
389 		gettext("Option %s requires a value.\n"), option);
390 	usage();
391 	exit(3);
392 }
393 
394 static int
395 parse_drvnum(char *pn)
396 {
397 	int drvnum;
398 
399 	/*
400 	 * Determine logical drive to seek after.
401 	 */
402 	if ((strlen(pn) == 1) && ((*pn >= 'c') && (*pn <= 'z'))) {
403 		drvnum = *pn - 'c' + 1;
404 	} else if ((*pn >= '0') && (*pn <= '9')) {
405 		char *d;
406 		int v = 0;
407 
408 		d = pn;
409 		while ((*d != '\0') && (*d >= '0') && (*d <= '9')) {
410 			v *= 10;
411 			v += *d - '0';
412 			d++;
413 		}
414 		if ((*d != '\0') || (v > 24)) {
415 			(void) fprintf(stderr,
416 			    gettext("%s: bogus logical drive specification.\n"),
417 			    pn);
418 			return (-1);
419 		}
420 		drvnum = v;
421 	} else if (strcmp(pn, "boot") == 0) {
422 		drvnum = 99;
423 	} else {
424 		(void) fprintf(stderr,
425 		    gettext("%s: bogus logical drive specification.\n"), pn);
426 		return (-1);
427 	}
428 
429 	return (drvnum);
430 }
431 
432 /*
433  * isDosDrive()
434  *	Boolean function.  Give it the systid field for an fdisk partition
435  *	and it decides if that's a systid that describes a DOS drive.  We
436  *	use systid values defined in sys/dktp/fdisk.h.
437  */
438 static int
439 isDosDrive(uchar_t checkMe)
440 {
441 	return ((checkMe == DOSOS12) || (checkMe == DOSOS16) ||
442 	    (checkMe == DOSHUGE) || (checkMe == FDISK_WINDOWS) ||
443 	    (checkMe == FDISK_EXT_WIN) || (checkMe == FDISK_FAT95) ||
444 	    (checkMe == DIAGPART));
445 }
446 
447 /*
448  * isDosExtended()
449  *	Boolean function.  Give it the systid field for an fdisk partition
450  *	and it decides if that's a systid that describes an extended DOS
451  *	partition.
452  */
453 static int
454 isDosExtended(uchar_t checkMe)
455 {
456 	return ((checkMe == EXTDOS) || (checkMe == FDISK_EXTLBA));
457 }
458 
459 /*
460  * isBootPart()
461  *	Boolean function.  Give it the systid field for an fdisk partition
462  *	and it decides if that's a systid that describes a Solaris boot
463  *	partition.
464  */
465 static int
466 isBootPart(uchar_t checkMe)
467 {
468 	return (checkMe == X86BOOT);
469 }
470 
471 off64_t
472 findPartitionOffset(int fd, char *ldrive)
473 {
474 	struct ipart part[FD_NUMPART];
475 	struct mboot extmboot;
476 	struct mboot mb;
477 	daddr_t xstartsect;
478 	off64_t nextseek = 0;
479 	off64_t lastseek = 0;
480 	off64_t found = 0;
481 	off64_t error = -1;
482 	int logicalDriveCount = 0;
483 	int extendedPart = -1;
484 	int primaryPart = -1;
485 	int bootPart = -1;
486 	int xnumsect = -1;
487 	int drvnum;
488 	int driveIndex;
489 	int i;
490 	/*
491 	 * Count of drives in the current extended partition's
492 	 * FDISK table, and indexes of the drives themselves.
493 	 */
494 	int extndDrives[FD_NUMPART];
495 	int numDrives = 0;
496 	/*
497 	 * Count of drives (beyond primary) in master boot record's
498 	 * FDISK table, and indexes of the drives themselves.
499 	 */
500 	int extraDrives[FD_NUMPART];
501 	int numExtraDrives = 0;
502 
503 	if ((drvnum = parse_drvnum(ldrive)) < 0)
504 		return (error);
505 
506 	if (read(fd, &mb, sizeof (mb)) != sizeof (mb)) {
507 		(void) fprintf(stderr,
508 		    gettext("Couldn't read a Master Boot Record\n"));
509 		return (error);
510 	}
511 
512 	if (ltohs(mb.signature) != BOOTSECSIG) {
513 		(void) fprintf(stderr,
514 		    gettext("Bad signature on master boot record (%x)\n"),
515 		    ltohs(mb.signature));
516 		return (error);
517 	}
518 
519 	/*
520 	 * Copy partition table into memory
521 	 */
522 	(void) memcpy(part, mb.parts, sizeof (part));
523 
524 	/*
525 	 * Get a summary of what is in the Master FDISK table.
526 	 * Normally we expect to find one partition marked as a DOS drive.
527 	 * This partition is the one Windows calls the primary dos partition.
528 	 * If the machine has any logical drives then we also expect
529 	 * to find a partition marked as an extended DOS partition.
530 	 *
531 	 * Sometimes we'll find multiple partitions marked as DOS drives.
532 	 * The Solaris fdisk program allows these partitions
533 	 * to be created, but Windows fdisk no longer does.  We still need
534 	 * to support these, though, since Windows does.  We also need to fix
535 	 * our fdisk to behave like the Windows version.
536 	 *
537 	 * It turns out that some off-the-shelf media have *only* an
538 	 * Extended partition, so we need to deal with that case as
539 	 * well.
540 	 *
541 	 * Only a single (the first) Extended or Boot Partition will
542 	 * be recognized.  Any others will be ignored.
543 	 */
544 	for (i = 0; i < FD_NUMPART; i++) {
545 		if (isDosDrive(part[i].systid)) {
546 			if (primaryPart < 0) {
547 				logicalDriveCount++;
548 				primaryPart = i;
549 			} else {
550 				extraDrives[numExtraDrives++] = i;
551 			}
552 			continue;
553 		}
554 		if ((extendedPart < 0) && isDosExtended(part[i].systid)) {
555 			extendedPart = i;
556 			continue;
557 		}
558 		if ((bootPart < 0) && isBootPart(part[i].systid)) {
559 			bootPart = i;
560 			continue;
561 		}
562 	}
563 
564 	if (drvnum == BOOT_PARTITION_DRIVE) {
565 		if (bootPart < 0) {
566 			(void) fprintf(stderr,
567 			    gettext("No boot partition found on drive\n"));
568 			return (error);
569 		}
570 		found = ltohi(part[bootPart].relsect) * BPSEC;
571 		return (found);
572 	}
573 
574 	if (drvnum == PRIMARY_DOS_DRIVE && primaryPart >= 0) {
575 		found = ltohi(part[primaryPart].relsect) * BPSEC;
576 		return (found);
577 	}
578 
579 	/*
580 	 * We are not looking for the C: drive (or there was no primary
581 	 * drive found), so we had better have an extended partition or
582 	 * extra drives in the Master FDISK table.
583 	 */
584 	if ((extendedPart < 0) && (numExtraDrives == 0)) {
585 		(void) fprintf(stderr,
586 		    gettext("No such logical drive "
587 		    "(missing extended partition entry)\n"));
588 		return (error);
589 	}
590 
591 	if (extendedPart >= 0) {
592 		nextseek = xstartsect = ltohi(part[extendedPart].relsect);
593 		xnumsect = ltohi(part[extendedPart].numsect);
594 		do {
595 			/*
596 			 *  If the seek would not cause us to change
597 			 *  position on the drive, then we're out of
598 			 *  extended partitions to examine.
599 			 */
600 			if (nextseek == lastseek)
601 				break;
602 			logicalDriveCount += numDrives;
603 			/*
604 			 *  Seek the next extended partition, and find
605 			 *  logical drives within it.
606 			 */
607 			if (lseek64(fd, nextseek * BPSEC, SEEK_SET) < 0 ||
608 			    read(fd, &extmboot, sizeof (extmboot)) !=
609 				sizeof (extmboot)) {
610 				perror(gettext("Unable to read extended "
611 					"partition record"));
612 				return (error);
613 			}
614 			(void) memcpy(part, extmboot.parts, sizeof (part));
615 			lastseek = nextseek;
616 			if (ltohs(extmboot.signature) != MBB_MAGIC) {
617 				(void) fprintf(stderr,
618 				    gettext("Bad signature on "
619 				    "extended partition\n"));
620 				return (error);
621 			}
622 			/*
623 			 *  Count up drives, and track where the next
624 			 *  extended partition is in case we need it.  We
625 			 *  are expecting only one extended partition.  If
626 			 *  there is more than one we'll only go to the
627 			 *  first one we see, but warn about ignoring.
628 			 */
629 			numDrives = 0;
630 			for (i = 0; i < FD_NUMPART; i++) {
631 				if (isDosDrive(part[i].systid)) {
632 					extndDrives[numDrives++] = i;
633 					continue;
634 				} else if (isDosExtended(part[i].systid)) {
635 					if (nextseek != lastseek) {
636 						/*
637 						 * Already found an extended
638 						 * partition in this table.
639 						 */
640 						(void) fprintf(stderr,
641 						    gettext("WARNING: "
642 						    "Ignoring unexpected "
643 						    "additional extended "
644 						    "partition"));
645 						continue;
646 					}
647 					nextseek = xstartsect +
648 					    ltohi(part[i].relsect);
649 					continue;
650 				}
651 			}
652 		} while (drvnum > logicalDriveCount + numDrives);
653 
654 		if (drvnum <= logicalDriveCount + numDrives) {
655 			/*
656 			 * The number of logical drives we've found thus
657 			 * far is enough to get us to the one we were
658 			 * searching for.
659 			 */
660 			driveIndex = logicalDriveCount + numDrives - drvnum;
661 			found =
662 			    ltohi(part[extndDrives[driveIndex]].relsect) +
663 			    lastseek;
664 			if (found > (xstartsect + xnumsect)) {
665 				(void) fprintf(stderr,
666 				    gettext("Logical drive start sector (%d) "
667 				    "is not within the partition!\n"), found);
668 				return (error);
669 			} else {
670 				found *= BPSEC;
671 			}
672 			return (found);
673 		} else {
674 			/*
675 			 * We ran out of extended dos partition
676 			 * drives.  The only hope now is to go
677 			 * back to extra drives defined in the master
678 			 * fdisk table.  But we overwrote that table
679 			 * already, so we must load it in again.
680 			 */
681 			logicalDriveCount += numDrives;
682 			(void) memcpy(part, mb.parts, sizeof (part));
683 		}
684 	}
685 	/*
686 	 *  Still haven't found the drive, is it an extra
687 	 *  drive defined in the main FDISK table?
688 	 */
689 	if (drvnum <= logicalDriveCount + numExtraDrives) {
690 		driveIndex = logicalDriveCount + numExtraDrives - drvnum;
691 		found = ltohi(part[extraDrives[driveIndex]].relsect) * BPSEC;
692 		return (found);
693 	}
694 	return (error);
695 }
696