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
20struct hfsplus_wd {
21	u32 ablk_size;
22	u16 ablk_start;
23	u16 embed_start;
24	u16 embed_count;
25};
26
27static 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
57static 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 */
88int 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