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/fs/partitions/msdos.c

https://bitbucket.org/cyanogenmod/android_kernel_asus_tf300t
C | 552 lines | 388 code | 58 blank | 106 comment | 122 complexity | 617f6c23fc63ae163548b1b7fea87061 MD5 | raw file
Possible License(s): LGPL-2.0, AGPL-1.0, GPL-2.0
  1/*
  2 *  fs/partitions/msdos.c
  3 *
  4 *  Code extracted from drivers/block/genhd.c
  5 *  Copyright (C) 1991-1998  Linus Torvalds
  6 *
  7 *  Thanks to Branko Lankester, lankeste@fwi.uva.nl, who found a bug
  8 *  in the early extended-partition checks and added DM partitions
  9 *
 10 *  Support for DiskManager v6.0x added by Mark Lord,
 11 *  with information provided by OnTrack.  This now works for linux fdisk
 12 *  and LILO, as well as loadlin and bootln.  Note that disks other than
 13 *  /dev/hda *must* have a "DOS" type 0x51 partition in the first slot (hda1).
 14 *
 15 *  More flexible handling of extended partitions - aeb, 950831
 16 *
 17 *  Check partition table on IDE disks for common CHS translations
 18 *
 19 *  Re-organised Feb 1998 Russell King
 20 */
 21#include <linux/msdos_fs.h>
 22
 23#include "check.h"
 24#include "msdos.h"
 25#include "efi.h"
 26
 27/*
 28 * Many architectures don't like unaligned accesses, while
 29 * the nr_sects and start_sect partition table entries are
 30 * at a 2 (mod 4) address.
 31 */
 32#include <asm/unaligned.h>
 33
 34#define SYS_IND(p)	get_unaligned(&p->sys_ind)
 35
 36static inline sector_t nr_sects(struct partition *p)
 37{
 38	return (sector_t)get_unaligned_le32(&p->nr_sects);
 39}
 40
 41static inline sector_t start_sect(struct partition *p)
 42{
 43	return (sector_t)get_unaligned_le32(&p->start_sect);
 44}
 45
 46static inline int is_extended_partition(struct partition *p)
 47{
 48	return (SYS_IND(p) == DOS_EXTENDED_PARTITION ||
 49		SYS_IND(p) == WIN98_EXTENDED_PARTITION ||
 50		SYS_IND(p) == LINUX_EXTENDED_PARTITION);
 51}
 52
 53#define MSDOS_LABEL_MAGIC1	0x55
 54#define MSDOS_LABEL_MAGIC2	0xAA
 55
 56static inline int
 57msdos_magic_present(unsigned char *p)
 58{
 59	return (p[0] == MSDOS_LABEL_MAGIC1 && p[1] == MSDOS_LABEL_MAGIC2);
 60}
 61
 62/* Value is EBCDIC 'IBMA' */
 63#define AIX_LABEL_MAGIC1	0xC9
 64#define AIX_LABEL_MAGIC2	0xC2
 65#define AIX_LABEL_MAGIC3	0xD4
 66#define AIX_LABEL_MAGIC4	0xC1
 67static int aix_magic_present(struct parsed_partitions *state, unsigned char *p)
 68{
 69	struct partition *pt = (struct partition *) (p + 0x1be);
 70	Sector sect;
 71	unsigned char *d;
 72	int slot, ret = 0;
 73
 74	if (!(p[0] == AIX_LABEL_MAGIC1 &&
 75		p[1] == AIX_LABEL_MAGIC2 &&
 76		p[2] == AIX_LABEL_MAGIC3 &&
 77		p[3] == AIX_LABEL_MAGIC4))
 78		return 0;
 79	/* Assume the partition table is valid if Linux partitions exists */
 80	for (slot = 1; slot <= 4; slot++, pt++) {
 81		if (pt->sys_ind == LINUX_SWAP_PARTITION ||
 82			pt->sys_ind == LINUX_RAID_PARTITION ||
 83			pt->sys_ind == LINUX_DATA_PARTITION ||
 84			pt->sys_ind == LINUX_LVM_PARTITION ||
 85			is_extended_partition(pt))
 86			return 0;
 87	}
 88	d = read_part_sector(state, 7, &sect);
 89	if (d) {
 90		if (d[0] == '_' && d[1] == 'L' && d[2] == 'V' && d[3] == 'M')
 91			ret = 1;
 92		put_dev_sector(sect);
 93	};
 94	return ret;
 95}
 96
 97/*
 98 * Create devices for each logical partition in an extended partition.
 99 * The logical partitions form a linked list, with each entry being
100 * a partition table with two entries.  The first entry
101 * is the real data partition (with a start relative to the partition
102 * table start).  The second is a pointer to the next logical partition
103 * (with a start relative to the entire extended partition).
104 * We do not create a Linux partition for the partition tables, but
105 * only for the actual data partitions.
106 */
107
108static void parse_extended(struct parsed_partitions *state,
109			   sector_t first_sector, sector_t first_size)
110{
111	struct partition *p;
112	Sector sect;
113	unsigned char *data;
114	sector_t this_sector, this_size;
115	sector_t sector_size = bdev_logical_block_size(state->bdev) / 512;
116	int loopct = 0;		/* number of links followed
117				   without finding a data partition */
118	int i;
119
120	this_sector = first_sector;
121	this_size = first_size;
122
123	while (1) {
124		if (++loopct > 100)
125			return;
126		if (state->next == state->limit)
127			return;
128		data = read_part_sector(state, this_sector, &sect);
129		if (!data)
130			return;
131
132		if (!msdos_magic_present(data + 510))
133			goto done; 
134
135		p = (struct partition *) (data + 0x1be);
136
137		/*
138		 * Usually, the first entry is the real data partition,
139		 * the 2nd entry is the next extended partition, or empty,
140		 * and the 3rd and 4th entries are unused.
141		 * However, DRDOS sometimes has the extended partition as
142		 * the first entry (when the data partition is empty),
143		 * and OS/2 seems to use all four entries.
144		 */
145
146		/* 
147		 * First process the data partition(s)
148		 */
149		for (i=0; i<4; i++, p++) {
150			sector_t offs, size, next;
151			if (!nr_sects(p) || is_extended_partition(p))
152				continue;
153
154			/* Check the 3rd and 4th entries -
155			   these sometimes contain random garbage */
156			offs = start_sect(p)*sector_size;
157			size = nr_sects(p)*sector_size;
158			next = this_sector + offs;
159			if (i >= 2) {
160				if (offs + size > this_size)
161					continue;
162				if (next < first_sector)
163					continue;
164				if (next + size > first_sector + first_size)
165					continue;
166			}
167
168			put_partition(state, state->next, next, size);
169			if (SYS_IND(p) == LINUX_RAID_PARTITION)
170				state->parts[state->next].flags = ADDPART_FLAG_RAID;
171			loopct = 0;
172			if (++state->next == state->limit)
173				goto done;
174		}
175		/*
176		 * Next, process the (first) extended partition, if present.
177		 * (So far, there seems to be no reason to make
178		 *  parse_extended()  recursive and allow a tree
179		 *  of extended partitions.)
180		 * It should be a link to the next logical partition.
181		 */
182		p -= 4;
183		for (i=0; i<4; i++, p++)
184			if (nr_sects(p) && is_extended_partition(p))
185				break;
186		if (i == 4)
187			goto done;	 /* nothing left to do */
188
189		this_sector = first_sector + start_sect(p) * sector_size;
190		this_size = nr_sects(p) * sector_size;
191		put_dev_sector(sect);
192	}
193done:
194	put_dev_sector(sect);
195}
196
197/* james@bpgc.com: Solaris has a nasty indicator: 0x82 which also
198   indicates linux swap.  Be careful before believing this is Solaris. */
199
200static void parse_solaris_x86(struct parsed_partitions *state,
201			      sector_t offset, sector_t size, int origin)
202{
203#ifdef CONFIG_SOLARIS_X86_PARTITION
204	Sector sect;
205	struct solaris_x86_vtoc *v;
206	int i;
207	short max_nparts;
208
209	v = read_part_sector(state, offset + 1, &sect);
210	if (!v)
211		return;
212	if (le32_to_cpu(v->v_sanity) != SOLARIS_X86_VTOC_SANE) {
213		put_dev_sector(sect);
214		return;
215	}
216	{
217		char tmp[1 + BDEVNAME_SIZE + 10 + 11 + 1];
218
219		snprintf(tmp, sizeof(tmp), " %s%d: <solaris:", state->name, origin);
220		strlcat(state->pp_buf, tmp, PAGE_SIZE);
221	}
222	if (le32_to_cpu(v->v_version) != 1) {
223		char tmp[64];
224
225		snprintf(tmp, sizeof(tmp), "  cannot handle version %d vtoc>\n",
226			 le32_to_cpu(v->v_version));
227		strlcat(state->pp_buf, tmp, PAGE_SIZE);
228		put_dev_sector(sect);
229		return;
230	}
231	/* Ensure we can handle previous case of VTOC with 8 entries gracefully */
232	max_nparts = le16_to_cpu (v->v_nparts) > 8 ? SOLARIS_X86_NUMSLICE : 8;
233	for (i=0; i<max_nparts && state->next<state->limit; i++) {
234		struct solaris_x86_slice *s = &v->v_slice[i];
235		char tmp[3 + 10 + 1 + 1];
236
237		if (s->s_size == 0)
238			continue;
239		snprintf(tmp, sizeof(tmp), " [s%d]", i);
240		strlcat(state->pp_buf, tmp, PAGE_SIZE);
241		/* solaris partitions are relative to current MS-DOS
242		 * one; must add the offset of the current partition */
243		put_partition(state, state->next++,
244				 le32_to_cpu(s->s_start)+offset,
245				 le32_to_cpu(s->s_size));
246	}
247	put_dev_sector(sect);
248	strlcat(state->pp_buf, " >\n", PAGE_SIZE);
249#endif
250}
251
252#if defined(CONFIG_BSD_DISKLABEL)
253/* 
254 * Create devices for BSD partitions listed in a disklabel, under a
255 * dos-like partition. See parse_extended() for more information.
256 */
257static void parse_bsd(struct parsed_partitions *state,
258		      sector_t offset, sector_t size, int origin, char *flavour,
259		      int max_partitions)
260{
261	Sector sect;
262	struct bsd_disklabel *l;
263	struct bsd_partition *p;
264	char tmp[64];
265
266	l = read_part_sector(state, offset + 1, &sect);
267	if (!l)
268		return;
269	if (le32_to_cpu(l->d_magic) != BSD_DISKMAGIC) {
270		put_dev_sector(sect);
271		return;
272	}
273
274	snprintf(tmp, sizeof(tmp), " %s%d: <%s:", state->name, origin, flavour);
275	strlcat(state->pp_buf, tmp, PAGE_SIZE);
276
277	if (le16_to_cpu(l->d_npartitions) < max_partitions)
278		max_partitions = le16_to_cpu(l->d_npartitions);
279	for (p = l->d_partitions; p - l->d_partitions < max_partitions; p++) {
280		sector_t bsd_start, bsd_size;
281
282		if (state->next == state->limit)
283			break;
284		if (p->p_fstype == BSD_FS_UNUSED) 
285			continue;
286		bsd_start = le32_to_cpu(p->p_offset);
287		bsd_size = le32_to_cpu(p->p_size);
288		if (offset == bsd_start && size == bsd_size)
289			/* full parent partition, we have it already */
290			continue;
291		if (offset > bsd_start || offset+size < bsd_start+bsd_size) {
292			strlcat(state->pp_buf, "bad subpartition - ignored\n", PAGE_SIZE);
293			continue;
294		}
295		put_partition(state, state->next++, bsd_start, bsd_size);
296	}
297	put_dev_sector(sect);
298	if (le16_to_cpu(l->d_npartitions) > max_partitions) {
299		snprintf(tmp, sizeof(tmp), " (ignored %d more)",
300			 le16_to_cpu(l->d_npartitions) - max_partitions);
301		strlcat(state->pp_buf, tmp, PAGE_SIZE);
302	}
303	strlcat(state->pp_buf, " >\n", PAGE_SIZE);
304}
305#endif
306
307static void parse_freebsd(struct parsed_partitions *state,
308			  sector_t offset, sector_t size, int origin)
309{
310#ifdef CONFIG_BSD_DISKLABEL
311	parse_bsd(state, offset, size, origin, "bsd", BSD_MAXPARTITIONS);
312#endif
313}
314
315static void parse_netbsd(struct parsed_partitions *state,
316			 sector_t offset, sector_t size, int origin)
317{
318#ifdef CONFIG_BSD_DISKLABEL
319	parse_bsd(state, offset, size, origin, "netbsd", BSD_MAXPARTITIONS);
320#endif
321}
322
323static void parse_openbsd(struct parsed_partitions *state,
324			  sector_t offset, sector_t size, int origin)
325{
326#ifdef CONFIG_BSD_DISKLABEL
327	parse_bsd(state, offset, size, origin, "openbsd",
328		  OPENBSD_MAXPARTITIONS);
329#endif
330}
331
332/*
333 * Create devices for Unixware partitions listed in a disklabel, under a
334 * dos-like partition. See parse_extended() for more information.
335 */
336static void parse_unixware(struct parsed_partitions *state,
337			   sector_t offset, sector_t size, int origin)
338{
339#ifdef CONFIG_UNIXWARE_DISKLABEL
340	Sector sect;
341	struct unixware_disklabel *l;
342	struct unixware_slice *p;
343
344	l = read_part_sector(state, offset + 29, &sect);
345	if (!l)
346		return;
347	if (le32_to_cpu(l->d_magic) != UNIXWARE_DISKMAGIC ||
348	    le32_to_cpu(l->vtoc.v_magic) != UNIXWARE_DISKMAGIC2) {
349		put_dev_sector(sect);
350		return;
351	}
352	{
353		char tmp[1 + BDEVNAME_SIZE + 10 + 12 + 1];
354
355		snprintf(tmp, sizeof(tmp), " %s%d: <unixware:", state->name, origin);
356		strlcat(state->pp_buf, tmp, PAGE_SIZE);
357	}
358	p = &l->vtoc.v_slice[1];
359	/* I omit the 0th slice as it is the same as whole disk. */
360	while (p - &l->vtoc.v_slice[0] < UNIXWARE_NUMSLICE) {
361		if (state->next == state->limit)
362			break;
363
364		if (p->s_label != UNIXWARE_FS_UNUSED)
365			put_partition(state, state->next++,
366				      le32_to_cpu(p->start_sect),
367				      le32_to_cpu(p->nr_sects));
368		p++;
369	}
370	put_dev_sector(sect);
371	strlcat(state->pp_buf, " >\n", PAGE_SIZE);
372#endif
373}
374
375/*
376 * Minix 2.0.0/2.0.2 subpartition support.
377 * Anand Krishnamurthy <anandk@wiproge.med.ge.com>
378 * Rajeev V. Pillai    <rajeevvp@yahoo.com>
379 */
380static void parse_minix(struct parsed_partitions *state,
381			sector_t offset, sector_t size, int origin)
382{
383#ifdef CONFIG_MINIX_SUBPARTITION
384	Sector sect;
385	unsigned char *data;
386	struct partition *p;
387	int i;
388
389	data = read_part_sector(state, offset, &sect);
390	if (!data)
391		return;
392
393	p = (struct partition *)(data + 0x1be);
394
395	/* The first sector of a Minix partition can have either
396	 * a secondary MBR describing its subpartitions, or
397	 * the normal boot sector. */
398	if (msdos_magic_present (data + 510) &&
399	    SYS_IND(p) == MINIX_PARTITION) { /* subpartition table present */
400		char tmp[1 + BDEVNAME_SIZE + 10 + 9 + 1];
401
402		snprintf(tmp, sizeof(tmp), " %s%d: <minix:", state->name, origin);
403		strlcat(state->pp_buf, tmp, PAGE_SIZE);
404		for (i = 0; i < MINIX_NR_SUBPARTITIONS; i++, p++) {
405			if (state->next == state->limit)
406				break;
407			/* add each partition in use */
408			if (SYS_IND(p) == MINIX_PARTITION)
409				put_partition(state, state->next++,
410					      start_sect(p), nr_sects(p));
411		}
412		strlcat(state->pp_buf, " >\n", PAGE_SIZE);
413	}
414	put_dev_sector(sect);
415#endif /* CONFIG_MINIX_SUBPARTITION */
416}
417
418static struct {
419	unsigned char id;
420	void (*parse)(struct parsed_partitions *, sector_t, sector_t, int);
421} subtypes[] = {
422	{FREEBSD_PARTITION, parse_freebsd},
423	{NETBSD_PARTITION, parse_netbsd},
424	{OPENBSD_PARTITION, parse_openbsd},
425	{MINIX_PARTITION, parse_minix},
426	{UNIXWARE_PARTITION, parse_unixware},
427	{SOLARIS_X86_PARTITION, parse_solaris_x86},
428	{NEW_SOLARIS_X86_PARTITION, parse_solaris_x86},
429	{0, NULL},
430};
431 
432int msdos_partition(struct parsed_partitions *state)
433{
434	sector_t sector_size = bdev_logical_block_size(state->bdev) / 512;
435	Sector sect;
436	unsigned char *data;
437	struct partition *p;
438	struct fat_boot_sector *fb;
439	int slot;
440
441	data = read_part_sector(state, 0, &sect);
442	if (!data)
443		return -1;
444	if (!msdos_magic_present(data + 510)) {
445		put_dev_sector(sect);
446		return 0;
447	}
448
449	if (aix_magic_present(state, data)) {
450		put_dev_sector(sect);
451		strlcat(state->pp_buf, " [AIX]", PAGE_SIZE);
452		return 0;
453	}
454
455	/*
456	 * Now that the 55aa signature is present, this is probably
457	 * either the boot sector of a FAT filesystem or a DOS-type
458	 * partition table. Reject this in case the boot indicator
459	 * is not 0 or 0x80.
460	 */
461	p = (struct partition *) (data + 0x1be);
462	for (slot = 1; slot <= 4; slot++, p++) {
463		if (p->boot_ind != 0 && p->boot_ind != 0x80) {
464			/*
465			 * Even without a valid boot inidicator value
466			 * its still possible this is valid FAT filesystem
467			 * without a partition table.
468			 */
469			fb = (struct fat_boot_sector *) data;
470			if (slot == 1 && fb->reserved && fb->fats
471				&& fat_valid_media(fb->media)) {
472				strlcat(state->pp_buf, "\n", PAGE_SIZE);
473				put_dev_sector(sect);
474				return 1;
475			} else {
476				put_dev_sector(sect);
477				return 0;
478			}
479		}
480	}
481
482#ifdef CONFIG_EFI_PARTITION
483	p = (struct partition *) (data + 0x1be);
484	for (slot = 1 ; slot <= 4 ; slot++, p++) {
485		/* If this is an EFI GPT disk, msdos should ignore it. */
486		if (SYS_IND(p) == EFI_PMBR_OSTYPE_EFI_GPT) {
487			put_dev_sector(sect);
488			return 0;
489		}
490	}
491#endif
492	p = (struct partition *) (data + 0x1be);
493
494	/*
495	 * Look for partitions in two passes:
496	 * First find the primary and DOS-type extended partitions.
497	 * On the second pass look inside *BSD, Unixware and Solaris partitions.
498	 */
499
500	state->next = 5;
501	for (slot = 1 ; slot <= 4 ; slot++, p++) {
502		sector_t start = start_sect(p)*sector_size;
503		sector_t size = nr_sects(p)*sector_size;
504		if (!size)
505			continue;
506		if (is_extended_partition(p)) {
507			/*
508			 * prevent someone doing mkfs or mkswap on an
509			 * extended partition, but leave room for LILO
510			 * FIXME: this uses one logical sector for > 512b
511			 * sector, although it may not be enough/proper.
512			 */
513			sector_t n = 2;
514			n = min(size, max(sector_size, n));
515			put_partition(state, slot, start, n);
516
517			strlcat(state->pp_buf, " <", PAGE_SIZE);
518			parse_extended(state, start, size);
519			strlcat(state->pp_buf, " >", PAGE_SIZE);
520			continue;
521		}
522		put_partition(state, slot, start, size);
523		if (SYS_IND(p) == LINUX_RAID_PARTITION)
524			state->parts[slot].flags = ADDPART_FLAG_RAID;
525		if (SYS_IND(p) == DM6_PARTITION)
526			strlcat(state->pp_buf, "[DM]", PAGE_SIZE);
527		if (SYS_IND(p) == EZD_PARTITION)
528			strlcat(state->pp_buf, "[EZD]", PAGE_SIZE);
529	}
530
531	strlcat(state->pp_buf, "\n", PAGE_SIZE);
532
533	/* second pass - output for each on a separate line */
534	p = (struct partition *) (0x1be + data);
535	for (slot = 1 ; slot <= 4 ; slot++, p++) {
536		unsigned char id = SYS_IND(p);
537		int n;
538
539		if (!nr_sects(p))
540			continue;
541
542		for (n = 0; subtypes[n].parse && id != subtypes[n].id; n++)
543			;
544
545		if (!subtypes[n].parse)
546			continue;
547		subtypes[n].parse(state, start_sect(p) * sector_size,
548				  nr_sects(p) * sector_size, slot);
549	}
550	put_dev_sector(sect);
551	return 1;
552}