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