fs/sysv: dereferencing ERR_PTR()
[linux-2.6-block.git] / fs / partitions / msdos.c
CommitLineData
1da177e4
LT
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 */
0607fd02 21#include <linux/msdos_fs.h>
1da177e4
LT
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
3fbf586c 34#define SYS_IND(p) get_unaligned(&p->sys_ind)
1da177e4 35
3fbf586c
DT
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}
1da177e4
LT
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
e1dfa92d
OH
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(unsigned char *p, struct block_device *bdev)
68{
4419d1ac 69 struct partition *pt = (struct partition *) (p + 0x1be);
e1dfa92d
OH
70 Sector sect;
71 unsigned char *d;
4419d1ac 72 int slot, ret = 0;
e1dfa92d 73
a470e18f
OH
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))
e1dfa92d 78 return 0;
4419d1ac
OH
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 }
e1dfa92d
OH
88 d = read_dev_sector(bdev, 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
1da177e4
LT
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
109parse_extended(struct parsed_partitions *state, struct block_device *bdev,
3fbf586c 110 sector_t first_sector, sector_t first_size)
1da177e4
LT
111{
112 struct partition *p;
113 Sector sect;
114 unsigned char *data;
3fbf586c
DT
115 sector_t this_sector, this_size;
116 sector_t sector_size = bdev_logical_block_size(bdev) / 512;
1da177e4
LT
117 int loopct = 0; /* number of links followed
118 without finding a data partition */
119 int i;
120
121 this_sector = first_sector;
122 this_size = first_size;
123
124 while (1) {
125 if (++loopct > 100)
126 return;
127 if (state->next == state->limit)
128 return;
129 data = read_dev_sector(bdev, this_sector, &sect);
130 if (!data)
131 return;
132
133 if (!msdos_magic_present(data + 510))
134 goto done;
135
136 p = (struct partition *) (data + 0x1be);
137
138 /*
139 * Usually, the first entry is the real data partition,
140 * the 2nd entry is the next extended partition, or empty,
141 * and the 3rd and 4th entries are unused.
142 * However, DRDOS sometimes has the extended partition as
143 * the first entry (when the data partition is empty),
144 * and OS/2 seems to use all four entries.
145 */
146
147 /*
148 * First process the data partition(s)
149 */
150 for (i=0; i<4; i++, p++) {
3fbf586c
DT
151 sector_t offs, size, next;
152 if (!nr_sects(p) || is_extended_partition(p))
1da177e4
LT
153 continue;
154
155 /* Check the 3rd and 4th entries -
156 these sometimes contain random garbage */
3fbf586c
DT
157 offs = start_sect(p)*sector_size;
158 size = nr_sects(p)*sector_size;
1da177e4
LT
159 next = this_sector + offs;
160 if (i >= 2) {
161 if (offs + size > this_size)
162 continue;
163 if (next < first_sector)
164 continue;
165 if (next + size > first_sector + first_size)
166 continue;
167 }
168
169 put_partition(state, state->next, next, size);
170 if (SYS_IND(p) == LINUX_RAID_PARTITION)
d18d7682 171 state->parts[state->next].flags = ADDPART_FLAG_RAID;
1da177e4
LT
172 loopct = 0;
173 if (++state->next == state->limit)
174 goto done;
175 }
176 /*
177 * Next, process the (first) extended partition, if present.
178 * (So far, there seems to be no reason to make
179 * parse_extended() recursive and allow a tree
180 * of extended partitions.)
181 * It should be a link to the next logical partition.
182 */
183 p -= 4;
184 for (i=0; i<4; i++, p++)
3fbf586c 185 if (nr_sects(p) && is_extended_partition(p))
1da177e4
LT
186 break;
187 if (i == 4)
188 goto done; /* nothing left to do */
189
3fbf586c
DT
190 this_sector = first_sector + start_sect(p) * sector_size;
191 this_size = nr_sects(p) * sector_size;
1da177e4
LT
192 put_dev_sector(sect);
193 }
194done:
195 put_dev_sector(sect);
196}
197
198/* james@bpgc.com: Solaris has a nasty indicator: 0x82 which also
199 indicates linux swap. Be careful before believing this is Solaris. */
200
201static void
202parse_solaris_x86(struct parsed_partitions *state, struct block_device *bdev,
3fbf586c 203 sector_t offset, sector_t size, int origin)
1da177e4
LT
204{
205#ifdef CONFIG_SOLARIS_X86_PARTITION
206 Sector sect;
207 struct solaris_x86_vtoc *v;
208 int i;
b84d8796 209 short max_nparts;
1da177e4
LT
210
211 v = (struct solaris_x86_vtoc *)read_dev_sector(bdev, offset+1, &sect);
212 if (!v)
213 return;
214 if (le32_to_cpu(v->v_sanity) != SOLARIS_X86_VTOC_SANE) {
215 put_dev_sector(sect);
216 return;
217 }
218 printk(" %s%d: <solaris:", state->name, origin);
219 if (le32_to_cpu(v->v_version) != 1) {
220 printk(" cannot handle version %d vtoc>\n",
221 le32_to_cpu(v->v_version));
222 put_dev_sector(sect);
223 return;
224 }
b84d8796
MF
225 /* Ensure we can handle previous case of VTOC with 8 entries gracefully */
226 max_nparts = le16_to_cpu (v->v_nparts) > 8 ? SOLARIS_X86_NUMSLICE : 8;
227 for (i=0; i<max_nparts && state->next<state->limit; i++) {
1da177e4
LT
228 struct solaris_x86_slice *s = &v->v_slice[i];
229 if (s->s_size == 0)
230 continue;
231 printk(" [s%d]", i);
232 /* solaris partitions are relative to current MS-DOS
233 * one; must add the offset of the current partition */
234 put_partition(state, state->next++,
235 le32_to_cpu(s->s_start)+offset,
236 le32_to_cpu(s->s_size));
237 }
238 put_dev_sector(sect);
239 printk(" >\n");
240#endif
241}
242
486fd404 243#if defined(CONFIG_BSD_DISKLABEL)
1da177e4
LT
244/*
245 * Create devices for BSD partitions listed in a disklabel, under a
246 * dos-like partition. See parse_extended() for more information.
247 */
486fd404 248static void
1da177e4 249parse_bsd(struct parsed_partitions *state, struct block_device *bdev,
3fbf586c 250 sector_t offset, sector_t size, int origin, char *flavour,
1da177e4
LT
251 int max_partitions)
252{
253 Sector sect;
254 struct bsd_disklabel *l;
255 struct bsd_partition *p;
256
257 l = (struct bsd_disklabel *)read_dev_sector(bdev, offset+1, &sect);
258 if (!l)
259 return;
260 if (le32_to_cpu(l->d_magic) != BSD_DISKMAGIC) {
261 put_dev_sector(sect);
262 return;
263 }
264 printk(" %s%d: <%s:", state->name, origin, flavour);
265
266 if (le16_to_cpu(l->d_npartitions) < max_partitions)
267 max_partitions = le16_to_cpu(l->d_npartitions);
268 for (p = l->d_partitions; p - l->d_partitions < max_partitions; p++) {
3fbf586c 269 sector_t bsd_start, bsd_size;
1da177e4
LT
270
271 if (state->next == state->limit)
272 break;
273 if (p->p_fstype == BSD_FS_UNUSED)
274 continue;
275 bsd_start = le32_to_cpu(p->p_offset);
276 bsd_size = le32_to_cpu(p->p_size);
277 if (offset == bsd_start && size == bsd_size)
278 /* full parent partition, we have it already */
279 continue;
280 if (offset > bsd_start || offset+size < bsd_start+bsd_size) {
281 printk("bad subpartition - ignored\n");
282 continue;
283 }
284 put_partition(state, state->next++, bsd_start, bsd_size);
285 }
286 put_dev_sector(sect);
287 if (le16_to_cpu(l->d_npartitions) > max_partitions)
288 printk(" (ignored %d more)",
289 le16_to_cpu(l->d_npartitions) - max_partitions);
290 printk(" >\n");
291}
292#endif
293
294static void
295parse_freebsd(struct parsed_partitions *state, struct block_device *bdev,
3fbf586c 296 sector_t offset, sector_t size, int origin)
1da177e4
LT
297{
298#ifdef CONFIG_BSD_DISKLABEL
299 parse_bsd(state, bdev, offset, size, origin,
300 "bsd", BSD_MAXPARTITIONS);
301#endif
302}
303
304static void
305parse_netbsd(struct parsed_partitions *state, struct block_device *bdev,
3fbf586c 306 sector_t offset, sector_t size, int origin)
1da177e4
LT
307{
308#ifdef CONFIG_BSD_DISKLABEL
309 parse_bsd(state, bdev, offset, size, origin,
310 "netbsd", BSD_MAXPARTITIONS);
311#endif
312}
313
314static void
315parse_openbsd(struct parsed_partitions *state, struct block_device *bdev,
3fbf586c 316 sector_t offset, sector_t size, int origin)
1da177e4
LT
317{
318#ifdef CONFIG_BSD_DISKLABEL
319 parse_bsd(state, bdev, offset, size, origin,
320 "openbsd", OPENBSD_MAXPARTITIONS);
321#endif
322}
323
324/*
325 * Create devices for Unixware partitions listed in a disklabel, under a
326 * dos-like partition. See parse_extended() for more information.
327 */
328static void
329parse_unixware(struct parsed_partitions *state, struct block_device *bdev,
3fbf586c 330 sector_t offset, sector_t size, int origin)
1da177e4
LT
331{
332#ifdef CONFIG_UNIXWARE_DISKLABEL
333 Sector sect;
334 struct unixware_disklabel *l;
335 struct unixware_slice *p;
336
337 l = (struct unixware_disklabel *)read_dev_sector(bdev, offset+29, &sect);
338 if (!l)
339 return;
340 if (le32_to_cpu(l->d_magic) != UNIXWARE_DISKMAGIC ||
341 le32_to_cpu(l->vtoc.v_magic) != UNIXWARE_DISKMAGIC2) {
342 put_dev_sector(sect);
343 return;
344 }
345 printk(" %s%d: <unixware:", state->name, origin);
346 p = &l->vtoc.v_slice[1];
347 /* I omit the 0th slice as it is the same as whole disk. */
348 while (p - &l->vtoc.v_slice[0] < UNIXWARE_NUMSLICE) {
349 if (state->next == state->limit)
350 break;
351
352 if (p->s_label != UNIXWARE_FS_UNUSED)
353 put_partition(state, state->next++,
3fbf586c
DT
354 le32_to_cpu(p->start_sect),
355 le32_to_cpu(p->nr_sects));
1da177e4
LT
356 p++;
357 }
358 put_dev_sector(sect);
359 printk(" >\n");
360#endif
361}
362
363/*
364 * Minix 2.0.0/2.0.2 subpartition support.
365 * Anand Krishnamurthy <anandk@wiproge.med.ge.com>
366 * Rajeev V. Pillai <rajeevvp@yahoo.com>
367 */
368static void
369parse_minix(struct parsed_partitions *state, struct block_device *bdev,
3fbf586c 370 sector_t offset, sector_t size, int origin)
1da177e4
LT
371{
372#ifdef CONFIG_MINIX_SUBPARTITION
373 Sector sect;
374 unsigned char *data;
375 struct partition *p;
376 int i;
377
378 data = read_dev_sector(bdev, offset, &sect);
379 if (!data)
380 return;
381
382 p = (struct partition *)(data + 0x1be);
383
384 /* The first sector of a Minix partition can have either
385 * a secondary MBR describing its subpartitions, or
386 * the normal boot sector. */
387 if (msdos_magic_present (data + 510) &&
388 SYS_IND(p) == MINIX_PARTITION) { /* subpartition table present */
389
390 printk(" %s%d: <minix:", state->name, origin);
391 for (i = 0; i < MINIX_NR_SUBPARTITIONS; i++, p++) {
392 if (state->next == state->limit)
393 break;
394 /* add each partition in use */
395 if (SYS_IND(p) == MINIX_PARTITION)
396 put_partition(state, state->next++,
3fbf586c 397 start_sect(p), nr_sects(p));
1da177e4
LT
398 }
399 printk(" >\n");
400 }
401 put_dev_sector(sect);
402#endif /* CONFIG_MINIX_SUBPARTITION */
403}
404
405static struct {
406 unsigned char id;
407 void (*parse)(struct parsed_partitions *, struct block_device *,
3fbf586c 408 sector_t, sector_t, int);
1da177e4
LT
409} subtypes[] = {
410 {FREEBSD_PARTITION, parse_freebsd},
411 {NETBSD_PARTITION, parse_netbsd},
412 {OPENBSD_PARTITION, parse_openbsd},
413 {MINIX_PARTITION, parse_minix},
414 {UNIXWARE_PARTITION, parse_unixware},
415 {SOLARIS_X86_PARTITION, parse_solaris_x86},
416 {NEW_SOLARIS_X86_PARTITION, parse_solaris_x86},
417 {0, NULL},
418};
419
420int msdos_partition(struct parsed_partitions *state, struct block_device *bdev)
421{
3fbf586c 422 sector_t sector_size = bdev_logical_block_size(bdev) / 512;
1da177e4
LT
423 Sector sect;
424 unsigned char *data;
425 struct partition *p;
0607fd02 426 struct fat_boot_sector *fb;
1da177e4
LT
427 int slot;
428
429 data = read_dev_sector(bdev, 0, &sect);
430 if (!data)
431 return -1;
432 if (!msdos_magic_present(data + 510)) {
433 put_dev_sector(sect);
434 return 0;
435 }
436
e1dfa92d
OH
437 if (aix_magic_present(data, bdev)) {
438 put_dev_sector(sect);
439 printk( " [AIX]");
440 return 0;
441 }
442
1da177e4
LT
443 /*
444 * Now that the 55aa signature is present, this is probably
445 * either the boot sector of a FAT filesystem or a DOS-type
446 * partition table. Reject this in case the boot indicator
447 * is not 0 or 0x80.
448 */
449 p = (struct partition *) (data + 0x1be);
450 for (slot = 1; slot <= 4; slot++, p++) {
451 if (p->boot_ind != 0 && p->boot_ind != 0x80) {
0607fd02
FS
452 /*
453 * Even without a valid boot inidicator value
454 * its still possible this is valid FAT filesystem
455 * without a partition table.
456 */
457 fb = (struct fat_boot_sector *) data;
458 if (slot == 1 && fb->reserved && fb->fats
459 && fat_valid_media(fb->media)) {
460 printk("\n");
461 put_dev_sector(sect);
462 return 1;
463 } else {
464 put_dev_sector(sect);
465 return 0;
466 }
1da177e4
LT
467 }
468 }
469
470#ifdef CONFIG_EFI_PARTITION
471 p = (struct partition *) (data + 0x1be);
472 for (slot = 1 ; slot <= 4 ; slot++, p++) {
473 /* If this is an EFI GPT disk, msdos should ignore it. */
474 if (SYS_IND(p) == EFI_PMBR_OSTYPE_EFI_GPT) {
475 put_dev_sector(sect);
476 return 0;
477 }
478 }
479#endif
480 p = (struct partition *) (data + 0x1be);
481
482 /*
483 * Look for partitions in two passes:
484 * First find the primary and DOS-type extended partitions.
485 * On the second pass look inside *BSD, Unixware and Solaris partitions.
486 */
487
488 state->next = 5;
489 for (slot = 1 ; slot <= 4 ; slot++, p++) {
3fbf586c
DT
490 sector_t start = start_sect(p)*sector_size;
491 sector_t size = nr_sects(p)*sector_size;
1da177e4
LT
492 if (!size)
493 continue;
494 if (is_extended_partition(p)) {
8e0cc811
OH
495 /*
496 * prevent someone doing mkfs or mkswap on an
497 * extended partition, but leave room for LILO
498 * FIXME: this uses one logical sector for > 512b
499 * sector, although it may not be enough/proper.
500 */
501 sector_t n = 2;
502 n = min(size, max(sector_size, n));
503 put_partition(state, slot, start, n);
504
1da177e4
LT
505 printk(" <");
506 parse_extended(state, bdev, start, size);
507 printk(" >");
508 continue;
509 }
510 put_partition(state, slot, start, size);
511 if (SYS_IND(p) == LINUX_RAID_PARTITION)
512 state->parts[slot].flags = 1;
513 if (SYS_IND(p) == DM6_PARTITION)
514 printk("[DM]");
515 if (SYS_IND(p) == EZD_PARTITION)
516 printk("[EZD]");
517 }
518
519 printk("\n");
520
521 /* second pass - output for each on a separate line */
522 p = (struct partition *) (0x1be + data);
523 for (slot = 1 ; slot <= 4 ; slot++, p++) {
524 unsigned char id = SYS_IND(p);
525 int n;
526
3fbf586c 527 if (!nr_sects(p))
1da177e4
LT
528 continue;
529
530 for (n = 0; subtypes[n].parse && id != subtypes[n].id; n++)
531 ;
532
533 if (!subtypes[n].parse)
534 continue;
3fbf586c
DT
535 subtypes[n].parse(state, bdev, start_sect(p)*sector_size,
536 nr_sects(p)*sector_size, slot);
1da177e4
LT
537 }
538 put_dev_sector(sect);
539 return 1;
540}