aboutsummaryrefslogtreecommitdiff
path: root/fs/hfsplus/wrapper.c
blob: 95455e839231ee33a186485204ffc91fa193efeb (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
/*
 *  linux/fs/hfsplus/wrapper.c
 *
 * Copyright (C) 2001
 * Brad Boyer (flar@allandria.com)
 * (C) 2003 Ardis Technologies <roman@ardistech.com>
 *
 * Handling of HFS wrappers around HFS+ volumes
 */

#include <linux/fs.h>
#include <linux/blkdev.h>
#include <linux/cdrom.h>
#include <linux/genhd.h>
#include <asm/unaligned.h>

#include "hfsplus_fs.h"
#include "hfsplus_raw.h"

struct hfsplus_wd {
	u32 ablk_size;
	u16 ablk_start;
	u16 embed_start;
	u16 embed_count;
};

static int hfsplus_read_mdb(void *bufptr, struct hfsplus_wd *wd)
{
	u32 extent;
	u16 attrib;

	if (be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_EMBEDSIG)) != HFSPLUS_VOLHEAD_SIG)
		return 0;

	attrib = be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ATTRIB));
	if (!(attrib & HFSP_WRAP_ATTRIB_SLOCK) ||
	   !(attrib & HFSP_WRAP_ATTRIB_SPARED))
		return 0;

	wd->ablk_size = be32_to_cpu(*(__be32 *)(bufptr + HFSP_WRAPOFF_ABLKSIZE));
	if (wd->ablk_size < HFSPLUS_SECTOR_SIZE)
		return 0;
	if (wd->ablk_size % HFSPLUS_SECTOR_SIZE)
		return 0;
	wd->ablk_start = be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ABLKSTART));

	extent = be32_to_cpu(get_unaligned((__be32 *)(bufptr + HFSP_WRAPOFF_EMBEDEXT)));
	wd->embed_start = (extent >> 16) & 0xFFFF;
	wd->embed_count = extent & 0xFFFF;

	return 1;
}

static int hfsplus_get_last_session(struct super_block *sb,
				    sector_t *start, sector_t *size)
{
	struct cdrom_multisession ms_info;
	struct cdrom_tocentry te;
	int res;

	/* default values */
	*start = 0;
	*size = sb->s_bdev->bd_inode->i_size >> 9;

	if (HFSPLUS_SB(sb).session >= 0) {
		te.cdte_track = HFSPLUS_SB(sb).session;
		te.cdte_format = CDROM_LBA;
		res = ioctl_by_bdev(sb->s_bdev, CDROMREADTOCENTRY, (unsigned long)&te);
		if (!res && (te.cdte_ctrl & CDROM_DATA_TRACK) == 4) {
			*start = (sector_t)te.cdte_addr.lba << 2;
			return 0;
		}
		printk(KERN_ERR "HFS: Invalid session number or type of track\n");
		return -EINVAL;
	}
	ms_info.addr_format = CDROM_LBA;
	res = ioctl_by_bdev(sb->s_bdev, CDROMMULTISESSION, (unsigned long)&ms_info);
	if (!res && ms_info.xa_flag)
		*start = (sector_t)ms_info.addr.lba << 2;
	return 0;
}

/* Find the volume header and fill in some minimum bits in superblock */
/* Takes in super block, returns true if good data read */
int hfsplus_read_wrapper(struct super_block *sb)
{
	struct buffer_head *bh;
	struct hfsplus_vh *vhdr;
	struct hfsplus_wd wd;
	sector_t part_start, part_size;
	u32 blocksize;

	blocksize = sb_min_blocksize(sb, HFSPLUS_SECTOR_SIZE);
	if (!blocksize)
		return -EINVAL;

	if (hfsplus_get_last_session(sb, &part_start, &part_size))
		return -EINVAL;
	while (1) {
		bh = sb_bread512(sb, part_start + HFSPLUS_VOLHEAD_SECTOR, vhdr);
		if (!bh)
			return -EIO;

		if (vhdr->signature == cpu_to_be16(HFSP_WRAP_MAGIC)) {
			if (!hfsplus_read_mdb(vhdr, &wd))
				goto error;
			wd.ablk_size >>= HFSPLUS_SECTOR_SHIFT;
			part_start += wd.ablk_start + wd.embed_start * wd.ablk_size;
			part_size = wd.embed_count * wd.ablk_size;
			brelse(bh);
			bh = sb_bread512(sb, part_start + HFSPLUS_VOLHEAD_SECTOR, vhdr);
			if (!bh)
				return -EIO;
		}
		if (vhdr->signature == cpu_to_be16(HFSPLUS_VOLHEAD_SIG))
			break;
		brelse(bh);

		/* check for a partition block
		 * (should do this only for cdrom/loop though)
		 */
		if (hfs_part_find(sb, &part_start, &part_size))
			return -EINVAL;
	}

	blocksize = be32_to_cpu(vhdr->blocksize);
	brelse(bh);

	/* block size must be at least as large as a sector
	 * and a multiple of 2
	 */
	if (blocksize < HFSPLUS_SECTOR_SIZE ||
	    ((blocksize - 1) & blocksize))
		return -EINVAL;
	HFSPLUS_SB(sb).alloc_blksz = blocksize;
	HFSPLUS_SB(sb).alloc_blksz_shift = 0;
	while ((blocksize >>= 1) != 0)
		HFSPLUS_SB(sb).alloc_blksz_shift++;
	blocksize = min(HFSPLUS_SB(sb).alloc_blksz, (u32)PAGE_SIZE);

	/* align block size to block offset */
	while (part_start & ((blocksize >> HFSPLUS_SECTOR_SHIFT) - 1))
		blocksize >>= 1;

	if (sb_set_blocksize(sb, blocksize) != blocksize) {
		printk("HFS+: unable to blocksize to %u!\n", blocksize);
		return -EINVAL;
	}

	HFSPLUS_SB(sb).blockoffset = part_start >>
			(sb->s_blocksize_bits - HFSPLUS_SECTOR_SHIFT);
	HFSPLUS_SB(sb).sect_count = part_size;
	HFSPLUS_SB(sb).fs_shift = HFSPLUS_SB(sb).alloc_blksz_shift -
			sb->s_blocksize_bits;

	bh = sb_bread512(sb, part_start + HFSPLUS_VOLHEAD_SECTOR, vhdr);
	if (!bh)
		return -EIO;

	/* should still be the same... */
	if (be16_to_cpu(vhdr->signature) != HFSPLUS_VOLHEAD_SIG)
		goto error;
	HFSPLUS_SB(sb).s_vhbh = bh;
	HFSPLUS_SB(sb).s_vhdr = vhdr;

	return 0;
 error:
	brelse(bh);
	return -EINVAL;
}