1 /*
2 * linux/fs/hfsplus/wrapper.c
3 *
4 * Copyright (C) 2001
5 * Brad Boyer (flar@allandria.com)
6 * (C) 2003 Ardis Technologies <roman@ardistech.com>
7 *
8 * Handling of HFS wrappers around HFS+ volumes
9 */
10
11 #include <linux/fs.h>
12 #include <linux/blkdev.h>
13 #include <linux/cdrom.h>
14 #include <linux/genhd.h>
15 #include <asm/unaligned.h>
16
17 #include "hfsplus_fs.h"
18 #include "hfsplus_raw.h"
19
20 struct hfsplus_wd {
21 u32 ablk_size;
22 u16 ablk_start;
23 u16 embed_start;
24 u16 embed_count;
25 };
26
27 static int hfsplus_read_mdb(void *bufptr, struct hfsplus_wd *wd)
28 {
29 u32 extent;
30 u16 attrib;
31 __be16 sig;
32
33 sig = *(__be16 *)(bufptr + HFSP_WRAPOFF_EMBEDSIG);
34 if (sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIG) &&
35 sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIGX))
36 return 0;
37
38 attrib = be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ATTRIB));
39 if (!(attrib & HFSP_WRAP_ATTRIB_SLOCK) ||
40 !(attrib & HFSP_WRAP_ATTRIB_SPARED))
41 return 0;
42
43 wd->ablk_size = be32_to_cpu(*(__be32 *)(bufptr + HFSP_WRAPOFF_ABLKSIZE));
44 if (wd->ablk_size < HFSPLUS_SECTOR_SIZE)
45 return 0;
46 if (wd->ablk_size % HFSPLUS_SECTOR_SIZE)
47 return 0;
48 wd->ablk_start = be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ABLKSTART));
49
50 extent = be32_to_cpu(get_unaligned((__be32 *)(bufptr + HFSP_WRAPOFF_EMBEDEXT)));
51 wd->embed_start = (extent >> 16) & 0xFFFF;
52 wd->embed_count = extent & 0xFFFF;
53
54 return 1;
55 }
56
57 static int hfsplus_get_last_session(struct super_block *sb,
58 sector_t *start, sector_t *size)
59 {
60 struct cdrom_multisession ms_info;
61 struct cdrom_tocentry te;
62 int res;
63
64 /* default values */
65 *start = 0;
66 *size = sb->s_bdev->bd_inode->i_size >> 9;
67
68 if (HFSPLUS_SB(sb).session >= 0) {
69 te.cdte_track = HFSPLUS_SB(sb).session;
70 te.cdte_format = CDROM_LBA;
71 res = ioctl_by_bdev(sb->s_bdev, CDROMREADTOCENTRY, (unsigned long)&te);
72 if (!res && (te.cdte_ctrl & CDROM_DATA_TRACK) == 4) {
73 *start = (sector_t)te.cdte_addr.lba << 2;
74 return 0;
75 }
76 printk(KERN_ERR "hfs: invalid session number or type of track\n");
77 return -EINVAL;
78 }
79 ms_info.addr_format = CDROM_LBA;
80 res = ioctl_by_bdev(sb->s_bdev, CDROMMULTISESSION, (unsigned long)&ms_info);
81 if (!res && ms_info.xa_flag)
82 *start = (sector_t)ms_info.addr.lba << 2;
83 return 0;
84 }
85
86 /* Find the volume header and fill in some minimum bits in superblock */
87 /* Takes in super block, returns true if good data read */
88 int hfsplus_read_wrapper(struct super_block *sb)
89 {
90 struct buffer_head *bh;
91 struct hfsplus_vh *vhdr;
92 struct hfsplus_wd wd;
93 sector_t part_start, part_size;
94 u32 blocksize;
95
96 blocksize = sb_min_blocksize(sb, HFSPLUS_SECTOR_SIZE);
97 if (!blocksize)
98 return -EINVAL;
99
100 if (hfsplus_get_last_session(sb, &part_start, &part_size))
101 return -EINVAL;
102 while (1) {
103 bh = sb_bread512(sb, part_start + HFSPLUS_VOLHEAD_SECTOR, vhdr);
104 if (!bh)
105 return -EIO;
106
107 if (vhdr->signature == cpu_to_be16(HFSP_WRAP_MAGIC)) {
108 if (!hfsplus_read_mdb(vhdr, &wd))
109 goto error;
110 wd.ablk_size >>= HFSPLUS_SECTOR_SHIFT;
111 part_start += wd.ablk_start + wd.embed_start * wd.ablk_size;
112 part_size = wd.embed_count * wd.ablk_size;
113 brelse(bh);
114 bh = sb_bread512(sb, part_start + HFSPLUS_VOLHEAD_SECTOR, vhdr);
115 if (!bh)
116 return -EIO;
117 }
118 if (vhdr->signature == cpu_to_be16(HFSPLUS_VOLHEAD_SIG))
119 break;
120 if (vhdr->signature == cpu_to_be16(HFSPLUS_VOLHEAD_SIGX)) {
121 HFSPLUS_SB(sb).flags |= HFSPLUS_SB_HFSX;
122 break;
123 }
124 brelse(bh);
125
126 /* check for a partition block
127 * (should do this only for cdrom/loop though)
128 */
129 if (hfs_part_find(sb, &part_start, &part_size))
130 return -EINVAL;
131 }
132
133 blocksize = be32_to_cpu(vhdr->blocksize);
134 brelse(bh);
135
136 /* block size must be at least as large as a sector
137 * and a multiple of 2
138 */
139 if (blocksize < HFSPLUS_SECTOR_SIZE ||
140 ((blocksize - 1) & blocksize))
141 return -EINVAL;
142 HFSPLUS_SB(sb).alloc_blksz = blocksize;
143 HFSPLUS_SB(sb).alloc_blksz_shift = 0;
144 while ((blocksize >>= 1) != 0)
145 HFSPLUS_SB(sb).alloc_blksz_shift++;
146 blocksize = min(HFSPLUS_SB(sb).alloc_blksz, (u32)PAGE_SIZE);
147
148 /* align block size to block offset */
149 while (part_start & ((blocksize >> HFSPLUS_SECTOR_SHIFT) - 1))
150 blocksize >>= 1;
151
152 if (sb_set_blocksize(sb, blocksize) != blocksize) {
153 printk(KERN_ERR "hfs: unable to set blocksize to %u!\n", blocksize);
154 return -EINVAL;
155 }
156
157 HFSPLUS_SB(sb).blockoffset = part_start >>
158 (sb->s_blocksize_bits - HFSPLUS_SECTOR_SHIFT);
159 HFSPLUS_SB(sb).sect_count = part_size;
160 HFSPLUS_SB(sb).fs_shift = HFSPLUS_SB(sb).alloc_blksz_shift -
161 sb->s_blocksize_bits;
162
163 bh = sb_bread512(sb, part_start + HFSPLUS_VOLHEAD_SECTOR, vhdr);
164 if (!bh)
165 return -EIO;
166
167 /* should still be the same... */
168 if (vhdr->signature != (HFSPLUS_SB(sb).flags & HFSPLUS_SB_HFSX ?
169 cpu_to_be16(HFSPLUS_VOLHEAD_SIGX) :
170 cpu_to_be16(HFSPLUS_VOLHEAD_SIG)))
171 goto error;
172 HFSPLUS_SB(sb).s_vhbh = bh;
173 HFSPLUS_SB(sb).s_vhdr = vhdr;
174
175 return 0;
176 error:
177 brelse(bh);
178 return -EINVAL;
179 }
180
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