xref: /freebsd/sys/geom/part/g_part_ebr.c (revision 9517e866259191fcd39434a97ad849a9b59b9b9f)
1 /*-
2  * Copyright (c) 2007-2009 Marcel Moolenaar
3  * 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  *
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25  */
26 
27 #include "opt_geom.h"
28 
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31 
32 #include <sys/param.h>
33 #include <sys/bio.h>
34 #include <sys/diskmbr.h>
35 #include <sys/endian.h>
36 #include <sys/kernel.h>
37 #include <sys/kobj.h>
38 #include <sys/limits.h>
39 #include <sys/lock.h>
40 #include <sys/malloc.h>
41 #include <sys/mutex.h>
42 #include <sys/queue.h>
43 #include <sys/sbuf.h>
44 #include <sys/systm.h>
45 #include <geom/geom.h>
46 #include <geom/part/g_part.h>
47 
48 #include "g_part_if.h"
49 
50 #define	EBRSIZE		512
51 
52 struct g_part_ebr_table {
53 	struct g_part_table	base;
54 };
55 
56 struct g_part_ebr_entry {
57 	struct g_part_entry	base;
58 	struct dos_partition	ent;
59 };
60 
61 static int g_part_ebr_add(struct g_part_table *, struct g_part_entry *,
62     struct g_part_parms *);
63 static int g_part_ebr_create(struct g_part_table *, struct g_part_parms *);
64 static int g_part_ebr_destroy(struct g_part_table *, struct g_part_parms *);
65 static void g_part_ebr_dumpconf(struct g_part_table *, struct g_part_entry *,
66     struct sbuf *, const char *);
67 static int g_part_ebr_dumpto(struct g_part_table *, struct g_part_entry *);
68 #if defined(GEOM_PART_EBR_COMPAT)
69 static void g_part_ebr_fullname(struct g_part_table *, struct g_part_entry *,
70     struct sbuf *, const char *);
71 #endif
72 static int g_part_ebr_modify(struct g_part_table *, struct g_part_entry *,
73     struct g_part_parms *);
74 static const char *g_part_ebr_name(struct g_part_table *, struct g_part_entry *,
75     char *, size_t);
76 static int g_part_ebr_precheck(struct g_part_table *, enum g_part_ctl,
77     struct g_part_parms *);
78 static int g_part_ebr_probe(struct g_part_table *, struct g_consumer *);
79 static int g_part_ebr_read(struct g_part_table *, struct g_consumer *);
80 static int g_part_ebr_setunset(struct g_part_table *, struct g_part_entry *,
81     const char *, unsigned int);
82 static const char *g_part_ebr_type(struct g_part_table *, struct g_part_entry *,
83     char *, size_t);
84 static int g_part_ebr_write(struct g_part_table *, struct g_consumer *);
85 
86 static kobj_method_t g_part_ebr_methods[] = {
87 	KOBJMETHOD(g_part_add,		g_part_ebr_add),
88 	KOBJMETHOD(g_part_create,	g_part_ebr_create),
89 	KOBJMETHOD(g_part_destroy,	g_part_ebr_destroy),
90 	KOBJMETHOD(g_part_dumpconf,	g_part_ebr_dumpconf),
91 	KOBJMETHOD(g_part_dumpto,	g_part_ebr_dumpto),
92 #if defined(GEOM_PART_EBR_COMPAT)
93 	KOBJMETHOD(g_part_fullname,	g_part_ebr_fullname),
94 #endif
95 	KOBJMETHOD(g_part_modify,	g_part_ebr_modify),
96 	KOBJMETHOD(g_part_name,		g_part_ebr_name),
97 	KOBJMETHOD(g_part_precheck,	g_part_ebr_precheck),
98 	KOBJMETHOD(g_part_probe,	g_part_ebr_probe),
99 	KOBJMETHOD(g_part_read,		g_part_ebr_read),
100 	KOBJMETHOD(g_part_setunset,	g_part_ebr_setunset),
101 	KOBJMETHOD(g_part_type,		g_part_ebr_type),
102 	KOBJMETHOD(g_part_write,	g_part_ebr_write),
103 	{ 0, 0 }
104 };
105 
106 static struct g_part_scheme g_part_ebr_scheme = {
107 	"EBR",
108 	g_part_ebr_methods,
109 	sizeof(struct g_part_ebr_table),
110 	.gps_entrysz = sizeof(struct g_part_ebr_entry),
111 	.gps_minent = 1,
112 	.gps_maxent = INT_MAX,
113 };
114 G_PART_SCHEME_DECLARE(g_part_ebr);
115 
116 static void ebr_set_chs(struct g_part_table *, uint32_t, u_char *, u_char *,
117     u_char *);
118 
119 static void
120 ebr_entry_decode(const char *p, struct dos_partition *ent)
121 {
122 	ent->dp_flag = p[0];
123 	ent->dp_shd = p[1];
124 	ent->dp_ssect = p[2];
125 	ent->dp_scyl = p[3];
126 	ent->dp_typ = p[4];
127 	ent->dp_ehd = p[5];
128 	ent->dp_esect = p[6];
129 	ent->dp_ecyl = p[7];
130 	ent->dp_start = le32dec(p + 8);
131 	ent->dp_size = le32dec(p + 12);
132 }
133 
134 static void
135 ebr_entry_link(struct g_part_table *table, uint32_t start, uint32_t end,
136    u_char *buf)
137 {
138 
139 	buf[0] = 0 /* dp_flag */;
140 	ebr_set_chs(table, start, &buf[3] /* dp_scyl */, &buf[1] /* dp_shd */,
141 	    &buf[2] /* dp_ssect */);
142 	buf[4] = 5 /* dp_typ */;
143 	ebr_set_chs(table, end, &buf[7] /* dp_ecyl */, &buf[5] /* dp_ehd */,
144 	    &buf[6] /* dp_esect */);
145 	le32enc(buf + 8, start);
146 	le32enc(buf + 12, end - start + 1);
147 }
148 
149 static int
150 ebr_parse_type(const char *type, u_char *dp_typ)
151 {
152 	const char *alias;
153 	char *endp;
154 	long lt;
155 
156 	if (type[0] == '!') {
157 		lt = strtol(type + 1, &endp, 0);
158 		if (type[1] == '\0' || *endp != '\0' || lt <= 0 || lt >= 256)
159 			return (EINVAL);
160 		*dp_typ = (u_char)lt;
161 		return (0);
162 	}
163 	alias = g_part_alias_name(G_PART_ALIAS_FREEBSD);
164 	if (!strcasecmp(type, alias)) {
165 		*dp_typ = DOSPTYP_386BSD;
166 		return (0);
167 	}
168 	return (EINVAL);
169 }
170 
171 static void
172 ebr_set_chs(struct g_part_table *table, uint32_t lba, u_char *cylp, u_char *hdp,
173     u_char *secp)
174 {
175 	uint32_t cyl, hd, sec;
176 
177 	sec = lba % table->gpt_sectors + 1;
178 	lba /= table->gpt_sectors;
179 	hd = lba % table->gpt_heads;
180 	lba /= table->gpt_heads;
181 	cyl = lba;
182 	if (cyl > 1023)
183 		sec = hd = cyl = ~0;
184 
185 	*cylp = cyl & 0xff;
186 	*hdp = hd & 0xff;
187 	*secp = (sec & 0x3f) | ((cyl >> 2) & 0xc0);
188 }
189 
190 static int
191 g_part_ebr_add(struct g_part_table *basetable, struct g_part_entry *baseentry,
192     struct g_part_parms *gpp)
193 {
194 	struct g_geom *gp;
195 	struct g_provider *pp;
196 	struct g_part_ebr_entry *entry;
197 	uint32_t start, size, sectors;
198 
199 	if (gpp->gpp_parms & G_PART_PARM_LABEL)
200 		return (EINVAL);
201 
202 	gp = basetable->gpt_gp;
203 	pp = LIST_FIRST(&gp->consumer)->provider;
204 	sectors = basetable->gpt_sectors;
205 
206 	entry = (struct g_part_ebr_entry *)baseentry;
207 
208 	start = gpp->gpp_start;
209 	size = gpp->gpp_size;
210 	if (size < 2 * sectors)
211 		return (EINVAL);
212 	if (start % sectors) {
213 		size = size - sectors + (start % sectors);
214 		start = start - (start % sectors) + sectors;
215 	}
216 	if (size % sectors)
217 		size = size - (size % sectors);
218 	if (size < 2 * sectors)
219 		return (EINVAL);
220 
221 	if (baseentry->gpe_deleted)
222 		bzero(&entry->ent, sizeof(entry->ent));
223 
224 	KASSERT(baseentry->gpe_start <= start, (__func__));
225 	KASSERT(baseentry->gpe_end >= start + size - 1, (__func__));
226 	baseentry->gpe_index = (start / sectors) + 1;
227 	baseentry->gpe_offset = (off_t)(start + sectors) * pp->sectorsize;
228 	baseentry->gpe_start = start;
229 	baseentry->gpe_end = start + size - 1;
230 	entry->ent.dp_start = sectors;
231 	entry->ent.dp_size = size - sectors;
232 	ebr_set_chs(basetable, entry->ent.dp_start, &entry->ent.dp_scyl,
233 	    &entry->ent.dp_shd, &entry->ent.dp_ssect);
234 	ebr_set_chs(basetable, baseentry->gpe_end, &entry->ent.dp_ecyl,
235 	    &entry->ent.dp_ehd, &entry->ent.dp_esect);
236 	return (ebr_parse_type(gpp->gpp_type, &entry->ent.dp_typ));
237 }
238 
239 static int
240 g_part_ebr_create(struct g_part_table *basetable, struct g_part_parms *gpp)
241 {
242 	char psn[8];
243 	struct g_consumer *cp;
244 	struct g_provider *pp;
245 	uint32_t msize;
246 	int error;
247 
248 	pp = gpp->gpp_provider;
249 
250 	if (pp->sectorsize < EBRSIZE)
251 		return (ENOSPC);
252 	if (pp->sectorsize > 4096)
253 		return (ENXIO);
254 
255 	/* Check that we have a parent and that it's a MBR. */
256 	if (basetable->gpt_depth == 0)
257 		return (ENXIO);
258 	cp = LIST_FIRST(&pp->consumers);
259 	error = g_getattr("PART::scheme", cp, &psn);
260 	if (error)
261 		return (error);
262 	if (strcmp(psn, "MBR"))
263 		return (ENXIO);
264 
265 	msize = MIN(pp->mediasize / pp->sectorsize, 0xffffffff);
266 	msize -= msize % basetable->gpt_sectors;
267 	basetable->gpt_first = 0;
268 	basetable->gpt_last = msize - 1;
269 	basetable->gpt_entries = msize / basetable->gpt_sectors;
270 	return (0);
271 }
272 
273 static int
274 g_part_ebr_destroy(struct g_part_table *basetable, struct g_part_parms *gpp)
275 {
276 
277 	/* Wipe the first sector to clear the partitioning. */
278 	basetable->gpt_smhead |= 1;
279 	return (0);
280 }
281 
282 static void
283 g_part_ebr_dumpconf(struct g_part_table *table, struct g_part_entry *baseentry,
284     struct sbuf *sb, const char *indent)
285 {
286 	struct g_part_ebr_entry *entry;
287 
288 	entry = (struct g_part_ebr_entry *)baseentry;
289 	if (indent == NULL) {
290 		/* conftxt: libdisk compatibility */
291 		sbuf_printf(sb, " xs MBREXT xt %u", entry->ent.dp_typ);
292 	} else if (entry != NULL) {
293 		/* confxml: partition entry information */
294 		sbuf_printf(sb, "%s<rawtype>%u</rawtype>\n", indent,
295 		    entry->ent.dp_typ);
296 		if (entry->ent.dp_flag & 0x80)
297 			sbuf_printf(sb, "%s<attrib>active</attrib>\n", indent);
298 	} else {
299 		/* confxml: scheme information */
300 	}
301 }
302 
303 static int
304 g_part_ebr_dumpto(struct g_part_table *table, struct g_part_entry *baseentry)
305 {
306 	struct g_part_ebr_entry *entry;
307 
308 	/* Allow dumping to a FreeBSD partition only. */
309 	entry = (struct g_part_ebr_entry *)baseentry;
310 	return ((entry->ent.dp_typ == DOSPTYP_386BSD) ? 1 : 0);
311 }
312 
313 #if defined(GEOM_PART_EBR_COMPAT)
314 static void
315 g_part_ebr_fullname(struct g_part_table *table, struct g_part_entry *entry,
316     struct sbuf *sb, const char *pfx)
317 {
318 	struct g_part_entry *iter;
319 	u_int idx;
320 
321 	idx = 5;
322 	LIST_FOREACH(iter, &table->gpt_entry, gpe_entry) {
323 		if (iter == entry)
324 			break;
325 		idx++;
326 	}
327 	sbuf_printf(sb, "%.*s%u", (int)strlen(pfx) - 1, pfx, idx);
328 }
329 #endif
330 
331 static int
332 g_part_ebr_modify(struct g_part_table *basetable,
333     struct g_part_entry *baseentry, struct g_part_parms *gpp)
334 {
335 	struct g_part_ebr_entry *entry;
336 
337 	if (gpp->gpp_parms & G_PART_PARM_LABEL)
338 		return (EINVAL);
339 
340 	entry = (struct g_part_ebr_entry *)baseentry;
341 	if (gpp->gpp_parms & G_PART_PARM_TYPE)
342 		return (ebr_parse_type(gpp->gpp_type, &entry->ent.dp_typ));
343 	return (0);
344 }
345 
346 static const char *
347 g_part_ebr_name(struct g_part_table *table, struct g_part_entry *entry,
348     char *buf, size_t bufsz)
349 {
350 
351 	snprintf(buf, bufsz, "+%08u", entry->gpe_index);
352 	return (buf);
353 }
354 
355 static int
356 g_part_ebr_precheck(struct g_part_table *table, enum g_part_ctl req,
357     struct g_part_parms *gpp)
358 {
359 #if defined(GEOM_PART_EBR_COMPAT)
360 	return (ECANCELED);
361 #else
362 	/*
363 	 * The index is a function of the start of the partition.
364 	 * This is not something the user can override, nor is it
365 	 * something the common code will do right. We can set the
366 	 * index now so that we get what we need.
367 	 */
368 	if (req == G_PART_CTL_ADD)
369 		gpp->gpp_index = (gpp->gpp_start / table->gpt_sectors) + 1;
370 	return (0);
371 #endif
372 }
373 
374 static int
375 g_part_ebr_probe(struct g_part_table *table, struct g_consumer *cp)
376 {
377 	char psn[8];
378 	struct g_provider *pp;
379 	u_char *buf, *p;
380 	int error, index, res, sum;
381 	uint16_t magic;
382 
383 	pp = cp->provider;
384 
385 	/* Sanity-check the provider. */
386 	if (pp->sectorsize < EBRSIZE || pp->mediasize < pp->sectorsize)
387 		return (ENOSPC);
388 	if (pp->sectorsize > 4096)
389 		return (ENXIO);
390 
391 	/* Check that we have a parent and that it's a MBR. */
392 	if (table->gpt_depth == 0)
393 		return (ENXIO);
394 	error = g_getattr("PART::scheme", cp, &psn);
395 	if (error)
396 		return (error);
397 	if (strcmp(psn, "MBR"))
398 		return (ENXIO);
399 
400 	/* Check that there's a EBR. */
401 	buf = g_read_data(cp, 0L, pp->sectorsize, &error);
402 	if (buf == NULL)
403 		return (error);
404 
405 	/* We goto out on mismatch. */
406 	res = ENXIO;
407 
408 	magic = le16dec(buf + DOSMAGICOFFSET);
409 	if (magic != DOSMAGIC)
410 		goto out;
411 
412 	/*
413 	 * The sector is all zeroes, except for the partition entries
414 	 * and some signatures or disk serial number. Those can be
415 	 * found in the 9 bytes immediately in front of the partition
416 	 * table.
417 	 */
418 	sum = 0;
419 	for (index = 0; index < DOSPARTOFF - 9; index++)
420 		sum += buf[index];
421 	if (sum != 0)
422 		goto out;
423 
424 	for (index = 0; index < NDOSPART; index++) {
425 		p = buf + DOSPARTOFF + index * DOSPARTSIZE;
426 		if (p[0] != 0 && p[0] != 0x80)
427 			goto out;
428 		if (index < 2)
429 			continue;
430 		/* The 3rd & 4th entries are always zero. */
431 		if ((le64dec(p+0) + le64dec(p+8)) != 0)
432 			goto out;
433 	}
434 
435 	res = G_PART_PROBE_PRI_NORM;
436 
437  out:
438 	g_free(buf);
439 	return (res);
440 }
441 
442 static int
443 g_part_ebr_read(struct g_part_table *basetable, struct g_consumer *cp)
444 {
445 	struct dos_partition ent[2];
446 	struct g_provider *pp;
447 	struct g_part_entry *baseentry;
448 	struct g_part_ebr_table *table;
449 	struct g_part_ebr_entry *entry;
450 	u_char *buf;
451 	off_t ofs, msize;
452 	u_int lba;
453 	int error, index;
454 
455 	pp = cp->provider;
456 	table = (struct g_part_ebr_table *)basetable;
457 	msize = pp->mediasize / pp->sectorsize;
458 
459 	lba = 0;
460 	while (1) {
461 		ofs = (off_t)lba * pp->sectorsize;
462 		buf = g_read_data(cp, ofs, pp->sectorsize, &error);
463 		if (buf == NULL)
464 			return (error);
465 
466 		ebr_entry_decode(buf + DOSPARTOFF + 0 * DOSPARTSIZE, ent + 0);
467 		ebr_entry_decode(buf + DOSPARTOFF + 1 * DOSPARTSIZE, ent + 1);
468 		g_free(buf);
469 
470 		if (ent[0].dp_typ == 0)
471 			break;
472 
473 		if (ent[0].dp_typ == 5 && ent[1].dp_typ == 0) {
474 			lba = ent[0].dp_start;
475 			continue;
476 		}
477 
478 		index = (lba / basetable->gpt_sectors) + 1;
479 		baseentry = (struct g_part_entry *)g_part_new_entry(basetable,
480 		    index, lba, lba + ent[0].dp_start + ent[0].dp_size - 1);
481 		baseentry->gpe_offset = (off_t)(lba + ent[0].dp_start) *
482 		    pp->sectorsize;
483 		entry = (struct g_part_ebr_entry *)baseentry;
484 		entry->ent = ent[0];
485 
486 		if (ent[1].dp_typ == 0)
487 			break;
488 
489 		lba = ent[1].dp_start;
490 	}
491 
492 	basetable->gpt_entries = msize / basetable->gpt_sectors;
493 	basetable->gpt_first = 0;
494 	basetable->gpt_last = msize - (msize % basetable->gpt_sectors) - 1;
495 	return (0);
496 }
497 
498 static int
499 g_part_ebr_setunset(struct g_part_table *table, struct g_part_entry *baseentry,
500     const char *attrib, unsigned int set)
501 {
502 	struct g_part_entry *iter;
503 	struct g_part_ebr_entry *entry;
504 	int changed;
505 
506 	if (strcasecmp(attrib, "active") != 0)
507 		return (EINVAL);
508 
509 	/* Only one entry can have the active attribute. */
510 	LIST_FOREACH(iter, &table->gpt_entry, gpe_entry) {
511 		if (iter->gpe_deleted)
512 			continue;
513 		changed = 0;
514 		entry = (struct g_part_ebr_entry *)iter;
515 		if (iter == baseentry) {
516 			if (set && (entry->ent.dp_flag & 0x80) == 0) {
517 				entry->ent.dp_flag |= 0x80;
518 				changed = 1;
519 			} else if (!set && (entry->ent.dp_flag & 0x80)) {
520 				entry->ent.dp_flag &= ~0x80;
521 				changed = 1;
522 			}
523 		} else {
524 			if (set && (entry->ent.dp_flag & 0x80)) {
525 				entry->ent.dp_flag &= ~0x80;
526 				changed = 1;
527 			}
528 		}
529 		if (changed && !iter->gpe_created)
530 			iter->gpe_modified = 1;
531 	}
532 	return (0);
533 }
534 
535 static const char *
536 g_part_ebr_type(struct g_part_table *basetable, struct g_part_entry *baseentry,
537     char *buf, size_t bufsz)
538 {
539 	struct g_part_ebr_entry *entry;
540 	int type;
541 
542 	entry = (struct g_part_ebr_entry *)baseentry;
543 	type = entry->ent.dp_typ;
544 	if (type == DOSPTYP_386BSD)
545 		return (g_part_alias_name(G_PART_ALIAS_FREEBSD));
546 	snprintf(buf, bufsz, "!%d", type);
547 	return (buf);
548 }
549 
550 static int
551 g_part_ebr_write(struct g_part_table *basetable, struct g_consumer *cp)
552 {
553 	struct g_provider *pp;
554 	struct g_part_entry *baseentry, *next;
555 	struct g_part_ebr_entry *entry;
556 	u_char *buf;
557 	u_char *p;
558 	int error;
559 
560 	pp = cp->provider;
561 	buf = g_malloc(pp->sectorsize, M_WAITOK | M_ZERO);
562 	le16enc(buf + DOSMAGICOFFSET, DOSMAGIC);
563 
564 	baseentry = LIST_FIRST(&basetable->gpt_entry);
565 	while (baseentry != NULL && baseentry->gpe_deleted)
566 		baseentry = LIST_NEXT(baseentry, gpe_entry);
567 
568 	/* Wipe-out the the first EBR when there are no slices. */
569 	if (baseentry == NULL) {
570 		error = g_write_data(cp, 0, buf, pp->sectorsize);
571 		goto out;
572 	}
573 
574 	/*
575 	 * If the first partition is not in LBA 0, we need to
576 	 * put a "link" EBR in LBA 0.
577 	 */
578 	if (baseentry->gpe_start != 0) {
579 		ebr_entry_link(basetable, (uint32_t)baseentry->gpe_start,
580 		    (uint32_t)baseentry->gpe_end, buf + DOSPARTOFF);
581 		error = g_write_data(cp, 0, buf, pp->sectorsize);
582 		if (error)
583 			goto out;
584 	}
585 
586 	do {
587 		entry = (struct g_part_ebr_entry *)baseentry;
588 
589 		p = buf + DOSPARTOFF;
590 		p[0] = entry->ent.dp_flag;
591 		p[1] = entry->ent.dp_shd;
592 		p[2] = entry->ent.dp_ssect;
593 		p[3] = entry->ent.dp_scyl;
594 		p[4] = entry->ent.dp_typ;
595 		p[5] = entry->ent.dp_ehd;
596 		p[6] = entry->ent.dp_esect;
597 		p[7] = entry->ent.dp_ecyl;
598 		le32enc(p + 8, entry->ent.dp_start);
599 		le32enc(p + 12, entry->ent.dp_size);
600 
601 		next = LIST_NEXT(baseentry, gpe_entry);
602 		while (next != NULL && next->gpe_deleted)
603 			next = LIST_NEXT(next, gpe_entry);
604 
605 		p += DOSPARTSIZE;
606 		if (next != NULL)
607 			ebr_entry_link(basetable, (uint32_t)next->gpe_start,
608 			    (uint32_t)next->gpe_end, p);
609 		else
610 			bzero(p, DOSPARTSIZE);
611 
612 		error = g_write_data(cp, baseentry->gpe_start * pp->sectorsize,
613 		    buf, pp->sectorsize);
614 
615 		baseentry = next;
616 	} while (!error && baseentry != NULL);
617 
618  out:
619 	g_free(buf);
620 	return (error);
621 }
622