Root/fs/hfs/part_tbl.c

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}
118

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