source: src/linux/laguna/linux-3.0/fs/hfsplus/part_tbl.c @ 17371

Last change on this file since 17371 was 17371, checked in by BrainSlayer, 22 months ago

linux 3.0 experimental for laguna
File size: 4.0 KB
Line 
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 */
39struct 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 */
61struct 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
70static 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
91static int hfs_parse_new_pmap(struct super_block *sb, struct new_pmap *pm,
92                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 res;
97        int i = 0;
98
99        do {
100                if (!memcmp(pm->pmPartType, "Apple_HFS", 9) &&
101                    (sbi->part < 0 || sbi->part == i)) {
102                        *part_start += be32_to_cpu(pm->pmPyPartStart);
103                        *part_size = be32_to_cpu(pm->pmPartBlkCnt);
104                        return 0;
105                }
106
107                if (++i >= size)
108                        return -ENOENT;
109
110                res = hfsplus_submit_bio(sb->s_bdev,
111                                         *part_start + HFS_PMAP_BLK + i,
112                                         pm, READ);
113                if (res)
114                        return res;
115        } while (pm->pmSig == cpu_to_be16(HFS_NEW_PMAP_MAGIC));
116
117        return -ENOENT;
118}
119
120/*
121 * Parse the partition map looking for the start and length of a
122 * HFS/HFS+ partition.
123 */
124int hfs_part_find(struct super_block *sb,
125                sector_t *part_start, sector_t *part_size)
126{
127        void *data;
128        int res;
129
130        data = kmalloc(HFSPLUS_SECTOR_SIZE, GFP_KERNEL);
131        if (!data)
132                return -ENOMEM;
133
134        res = hfsplus_submit_bio(sb->s_bdev, *part_start + HFS_PMAP_BLK,
135                                 data, READ);
136        if (res)
137                goto out;
138
139        switch (be16_to_cpu(*((__be16 *)data))) {
140        case HFS_OLD_PMAP_MAGIC:
141                res = hfs_parse_old_pmap(sb, data, part_start, part_size);
142                break;
143        case HFS_NEW_PMAP_MAGIC:
144                res = hfs_parse_new_pmap(sb, data, part_start, part_size);
145                break;
146        default:
147                res = -ENOENT;
148                break;
149        }
150out:
151        kfree(data);
152        return res;
153}
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