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1da177e4 | 1 | /* |
f30c2269 | 2 | * linux/fs/hfsplus/part_tbl.c |
1da177e4 LT |
3 | * |
4 | * Copyright (C) 1996-1997 Paul H. Hargrove | |
5 | * This file may be distributed under the terms of the GNU General Public License. | |
6 | * | |
7 | * Original code to handle the new style Mac partition table based on | |
8 | * a patch contributed by Holger Schemel (aeglos@valinor.owl.de). | |
9 | * | |
10 | * In function preconditions the term "valid" applied to a pointer to | |
11 | * a structure means that the pointer is non-NULL and the structure it | |
12 | * points to has all fields initialized to consistent values. | |
13 | * | |
14 | */ | |
15 | ||
16 | #include "hfsplus_fs.h" | |
17 | ||
18 | /* offsets to various blocks */ | |
19 | #define HFS_DD_BLK 0 /* Driver Descriptor block */ | |
20 | #define HFS_PMAP_BLK 1 /* First block of partition map */ | |
21 | #define HFS_MDB_BLK 2 /* Block (w/i partition) of MDB */ | |
22 | ||
23 | /* magic numbers for various disk blocks */ | |
24 | #define HFS_DRVR_DESC_MAGIC 0x4552 /* "ER": driver descriptor map */ | |
25 | #define HFS_OLD_PMAP_MAGIC 0x5453 /* "TS": old-type partition map */ | |
26 | #define HFS_NEW_PMAP_MAGIC 0x504D /* "PM": new-type partition map */ | |
27 | #define HFS_SUPER_MAGIC 0x4244 /* "BD": HFS MDB (super block) */ | |
28 | #define HFS_MFS_SUPER_MAGIC 0xD2D7 /* MFS MDB (super block) */ | |
29 | ||
30 | /* | |
31 | * The new style Mac partition map | |
32 | * | |
33 | * For each partition on the media there is a physical block (512-byte | |
34 | * block) containing one of these structures. These blocks are | |
35 | * contiguous starting at block 1. | |
36 | */ | |
37 | struct new_pmap { | |
38 | __be16 pmSig; /* signature */ | |
39 | __be16 reSigPad; /* padding */ | |
40 | __be32 pmMapBlkCnt; /* partition blocks count */ | |
41 | __be32 pmPyPartStart; /* physical block start of partition */ | |
42 | __be32 pmPartBlkCnt; /* physical block count of partition */ | |
43 | u8 pmPartName[32]; /* (null terminated?) string | |
44 | giving the name of this | |
45 | partition */ | |
46 | u8 pmPartType[32]; /* (null terminated?) string | |
47 | giving the type of this | |
48 | partition */ | |
49 | /* a bunch more stuff we don't need */ | |
50 | } __packed; | |
51 | ||
52 | /* | |
53 | * The old style Mac partition map | |
54 | * | |
55 | * The partition map consists for a 2-byte signature followed by an | |
56 | * array of these structures. The map is terminated with an all-zero | |
57 | * one of these. | |
58 | */ | |
59 | struct old_pmap { | |
60 | __be16 pdSig; /* Signature bytes */ | |
61 | struct old_pmap_entry { | |
62 | __be32 pdStart; | |
63 | __be32 pdSize; | |
64 | __be32 pdFSID; | |
65 | } pdEntry[42]; | |
66 | } __packed; | |
67 | ||
68 | /* | |
69 | * hfs_part_find() | |
70 | * | |
71 | * Parse the partition map looking for the | |
72 | * start and length of the 'part'th HFS partition. | |
73 | */ | |
74 | int hfs_part_find(struct super_block *sb, | |
75 | sector_t *part_start, sector_t *part_size) | |
76 | { | |
dd73a01a | 77 | struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb); |
1da177e4 LT |
78 | struct buffer_head *bh; |
79 | __be16 *data; | |
80 | int i, size, res; | |
81 | ||
82 | res = -ENOENT; | |
83 | bh = sb_bread512(sb, *part_start + HFS_PMAP_BLK, data); | |
84 | if (!bh) | |
85 | return -EIO; | |
86 | ||
87 | switch (be16_to_cpu(*data)) { | |
88 | case HFS_OLD_PMAP_MAGIC: | |
89 | { | |
90 | struct old_pmap *pm; | |
91 | struct old_pmap_entry *p; | |
92 | ||
93 | pm = (struct old_pmap *)bh->b_data; | |
94 | p = pm->pdEntry; | |
95 | size = 42; | |
96 | for (i = 0; i < size; p++, i++) { | |
97 | if (p->pdStart && p->pdSize && | |
98 | p->pdFSID == cpu_to_be32(0x54465331)/*"TFS1"*/ && | |
dd73a01a | 99 | (sbi->part < 0 || sbi->part == i)) { |
1da177e4 LT |
100 | *part_start += be32_to_cpu(p->pdStart); |
101 | *part_size = be32_to_cpu(p->pdSize); | |
102 | res = 0; | |
103 | } | |
104 | } | |
105 | break; | |
106 | } | |
107 | case HFS_NEW_PMAP_MAGIC: | |
108 | { | |
109 | struct new_pmap *pm; | |
110 | ||
111 | pm = (struct new_pmap *)bh->b_data; | |
112 | size = be32_to_cpu(pm->pmMapBlkCnt); | |
113 | for (i = 0; i < size;) { | |
114 | if (!memcmp(pm->pmPartType,"Apple_HFS", 9) && | |
dd73a01a | 115 | (sbi->part < 0 || sbi->part == i)) { |
1da177e4 LT |
116 | *part_start += be32_to_cpu(pm->pmPyPartStart); |
117 | *part_size = be32_to_cpu(pm->pmPartBlkCnt); | |
118 | res = 0; | |
119 | break; | |
120 | } | |
121 | brelse(bh); | |
122 | bh = sb_bread512(sb, *part_start + HFS_PMAP_BLK + ++i, pm); | |
123 | if (!bh) | |
124 | return -EIO; | |
125 | if (pm->pmSig != cpu_to_be16(HFS_NEW_PMAP_MAGIC)) | |
126 | break; | |
127 | } | |
128 | break; | |
129 | } | |
130 | } | |
131 | brelse(bh); | |
132 | ||
133 | return res; | |
134 | } |