1 | /* |
2 | * linux/fs/hfsplus/part_tbl.c |
3 | * |
4 | * Copyright (C) 1996-1997 Paul H. Hargrove |
5 | * This file may be distributed under the terms of |
6 | * 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 | * In function preconditions the term "valid" applied to a pointer to |
12 | * a structure means that the pointer is non-NULL and the structure it |
13 | * points to has all fields initialized to consistent values. |
14 | * |
15 | */ |
16 | |
17 | #include <linux/slab.h> |
18 | #include "hfsplus_fs.h" |
19 | |
20 | /* offsets to various blocks */ |
21 | #define HFS_DD_BLK 0 /* Driver Descriptor block */ |
22 | #define HFS_PMAP_BLK 1 /* First block of partition map */ |
23 | #define HFS_MDB_BLK 2 /* Block (w/i partition) of MDB */ |
24 | |
25 | /* magic numbers for various disk blocks */ |
26 | #define HFS_DRVR_DESC_MAGIC 0x4552 /* "ER": driver descriptor map */ |
27 | #define HFS_OLD_PMAP_MAGIC 0x5453 /* "TS": old-type partition map */ |
28 | #define HFS_NEW_PMAP_MAGIC 0x504D /* "PM": new-type partition map */ |
29 | #define HFS_SUPER_MAGIC 0x4244 /* "BD": HFS MDB (super block) */ |
30 | #define HFS_MFS_SUPER_MAGIC 0xD2D7 /* MFS MDB (super block) */ |
31 | |
32 | /* |
33 | * The new style Mac partition map |
34 | * |
35 | * For each partition on the media there is a physical block (512-byte |
36 | * block) containing one of these structures. These blocks are |
37 | * contiguous starting at block 1. |
38 | */ |
39 | struct new_pmap { |
40 | __be16 pmSig; /* signature */ |
41 | __be16 reSigPad; /* padding */ |
42 | __be32 pmMapBlkCnt; /* partition blocks count */ |
43 | __be32 pmPyPartStart; /* physical block start of partition */ |
44 | __be32 pmPartBlkCnt; /* physical block count of partition */ |
45 | u8 pmPartName[32]; /* (null terminated?) string |
46 | giving the name of this |
47 | partition */ |
48 | u8 pmPartType[32]; /* (null terminated?) string |
49 | giving the type of this |
50 | partition */ |
51 | /* a bunch more stuff we don't need */ |
52 | } __packed; |
53 | |
54 | /* |
55 | * The old style Mac partition map |
56 | * |
57 | * The partition map consists for a 2-byte signature followed by an |
58 | * array of these structures. The map is terminated with an all-zero |
59 | * one of these. |
60 | */ |
61 | struct old_pmap { |
62 | __be16 pdSig; /* Signature bytes */ |
63 | struct old_pmap_entry { |
64 | __be32 pdStart; |
65 | __be32 pdSize; |
66 | __be32 pdFSID; |
67 | } pdEntry[42]; |
68 | } __packed; |
69 | |
70 | static int hfs_parse_old_pmap(struct super_block *sb, struct old_pmap *pm, |
71 | sector_t *part_start, sector_t *part_size) |
72 | { |
73 | struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb); |
74 | int i; |
75 | |
76 | for (i = 0; i < 42; i++) { |
77 | struct old_pmap_entry *p = &pm->pdEntry[i]; |
78 | |
79 | if (p->pdStart && p->pdSize && |
80 | p->pdFSID == cpu_to_be32(0x54465331)/*"TFS1"*/ && |
81 | (sbi->part < 0 || sbi->part == i)) { |
82 | *part_start += be32_to_cpu(p->pdStart); |
83 | *part_size = be32_to_cpu(p->pdSize); |
84 | return 0; |
85 | } |
86 | } |
87 | |
88 | return -ENOENT; |
89 | } |
90 | |
91 | static int hfs_parse_new_pmap(struct super_block *sb, void *buf, |
92 | struct new_pmap *pm, sector_t *part_start, sector_t *part_size) |
93 | { |
94 | struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb); |
95 | int size = be32_to_cpu(pm->pmMapBlkCnt); |
96 | int buf_size = hfsplus_min_io_size(sb); |
97 | int res; |
98 | int i = 0; |
99 | |
100 | do { |
101 | if (!memcmp(p: pm->pmPartType, q: "Apple_HFS" , size: 9) && |
102 | (sbi->part < 0 || sbi->part == i)) { |
103 | *part_start += be32_to_cpu(pm->pmPyPartStart); |
104 | *part_size = be32_to_cpu(pm->pmPartBlkCnt); |
105 | return 0; |
106 | } |
107 | |
108 | if (++i >= size) |
109 | return -ENOENT; |
110 | |
111 | pm = (struct new_pmap *)((u8 *)pm + HFSPLUS_SECTOR_SIZE); |
112 | if ((u8 *)pm - (u8 *)buf >= buf_size) { |
113 | res = hfsplus_submit_bio(sb, |
114 | sector: *part_start + HFS_PMAP_BLK + i, |
115 | buf, data: (void **)&pm, opf: REQ_OP_READ); |
116 | if (res) |
117 | return res; |
118 | } |
119 | } while (pm->pmSig == cpu_to_be16(HFS_NEW_PMAP_MAGIC)); |
120 | |
121 | return -ENOENT; |
122 | } |
123 | |
124 | /* |
125 | * Parse the partition map looking for the start and length of a |
126 | * HFS/HFS+ partition. |
127 | */ |
128 | int hfs_part_find(struct super_block *sb, |
129 | sector_t *part_start, sector_t *part_size) |
130 | { |
131 | void *buf, *data; |
132 | int res; |
133 | |
134 | buf = kmalloc(size: hfsplus_min_io_size(sb), GFP_KERNEL); |
135 | if (!buf) |
136 | return -ENOMEM; |
137 | |
138 | res = hfsplus_submit_bio(sb, sector: *part_start + HFS_PMAP_BLK, |
139 | buf, data: &data, opf: REQ_OP_READ); |
140 | if (res) |
141 | goto out; |
142 | |
143 | switch (be16_to_cpu(*((__be16 *)data))) { |
144 | case HFS_OLD_PMAP_MAGIC: |
145 | res = hfs_parse_old_pmap(sb, pm: data, part_start, part_size); |
146 | break; |
147 | case HFS_NEW_PMAP_MAGIC: |
148 | res = hfs_parse_new_pmap(sb, buf, pm: data, part_start, part_size); |
149 | break; |
150 | default: |
151 | res = -ENOENT; |
152 | break; |
153 | } |
154 | out: |
155 | kfree(objp: buf); |
156 | return res; |
157 | } |
158 | |