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gerrit-public.fairphone.software / kernel / msm / 055ae4fdc1511c06b5aadb513239a6605ca458cd / . / fs / hfs / part_tbl.c
blob: 36add537d153e55ccb362b5b6f82694421b61867 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]1/*
2 * linux/fs/hfs/part_tbl.c
3 *
4 * Copyright (C) 1996-1997 Paul H. Hargrove
5 * (C) 2003 Ardis Technologies <roman@ardistech.com>
6 * This file may be distributed under the terms of the GNU General Public License.
7 *
8 * Original code to handle the new style Mac partition table based on
9 * a patch contributed by Holger Schemel (aeglos@valinor.owl.de).
10 */
11
12#include "hfs_fs.h"
13
14/*
15 * The new style Mac partition map
16 *
17 * For each partition on the media there is a physical block (512-byte
18 * block) containing one of these structures. These blocks are
19 * contiguous starting at block 1.
20 */
21struct new_pmap {
22 __be16 pmSig; /* signature */
23 __be16 reSigPad; /* padding */
24 __be32 pmMapBlkCnt; /* partition blocks count */
25 __be32 pmPyPartStart; /* physical block start of partition */
26 __be32 pmPartBlkCnt; /* physical block count of partition */
27 u8 pmPartName[32]; /* (null terminated?) string
28 giving the name of this
29 partition */
30 u8 pmPartType[32]; /* (null terminated?) string
31 giving the type of this
32 partition */
33 /* a bunch more stuff we don't need */
34} __packed;
35
36/*
37 * The old style Mac partition map
38 *
39 * The partition map consists for a 2-byte signature followed by an
40 * array of these structures. The map is terminated with an all-zero
41 * one of these.
42 */
43struct old_pmap {
44 __be16 pdSig; /* Signature bytes */
45 struct old_pmap_entry {
46 __be32 pdStart;
47 __be32 pdSize;
48 __be32 pdFSID;
49 } pdEntry[42];
50} __packed;
51
52/*
53 * hfs_part_find()
54 *
55 * Parse the partition map looking for the
56 * start and length of the 'part'th HFS partition.
57 */
58int hfs_part_find(struct super_block *sb,
59 sector_t *part_start, sector_t *part_size)
60{
61 struct buffer_head *bh;
62 __be16 *data;
63 int i, size, res;
64
65 res = -ENOENT;
66 bh = sb_bread512(sb, *part_start + HFS_PMAP_BLK, data);
67 if (!bh)
68 return -EIO;
69
70 switch (be16_to_cpu(*data)) {
71 case HFS_OLD_PMAP_MAGIC:
72 {
73 struct old_pmap *pm;
74 struct old_pmap_entry *p;
75
76 pm = (struct old_pmap *)bh->b_data;
77 p = pm->pdEntry;
78 size = 42;
79 for (i = 0; i < size; p++, i++) {
80 if (p->pdStart && p->pdSize &&
81 p->pdFSID == cpu_to_be32(0x54465331)/*"TFS1"*/ &&
82 (HFS_SB(sb)->part < 0 || HFS_SB(sb)->part == i)) {
83 *part_start += be32_to_cpu(p->pdStart);
84 *part_size = be32_to_cpu(p->pdSize);
85 res = 0;
86 }
87 }
88 break;
89 }
90 case HFS_NEW_PMAP_MAGIC:
91 {
92 struct new_pmap *pm;
93
94 pm = (struct new_pmap *)bh->b_data;
95 size = be32_to_cpu(pm->pmMapBlkCnt);
96 for (i = 0; i < size;) {
97 if (!memcmp(pm->pmPartType,"Apple_HFS", 9) &&
98 (HFS_SB(sb)->part < 0 || HFS_SB(sb)->part == i)) {
99 *part_start += be32_to_cpu(pm->pmPyPartStart);
100 *part_size = be32_to_cpu(pm->pmPartBlkCnt);
101 res = 0;
102 break;
103 }
104 brelse(bh);
105 bh = sb_bread512(sb, *part_start + HFS_PMAP_BLK + ++i, pm);
106 if (!bh)
107 return -EIO;
108 if (pm->pmSig != cpu_to_be16(HFS_NEW_PMAP_MAGIC))
109 break;
110 }
111 break;
112 }
113 }
114 brelse(bh);
115
116 return res;
117}