xref: /openbmc/linux/fs/hfsplus/wrapper.c (revision 87c2ce3b)
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 
32 	if (be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_EMBEDSIG)) != HFSPLUS_VOLHEAD_SIG)
33 		return 0;
34 
35 	attrib = be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ATTRIB));
36 	if (!(attrib & HFSP_WRAP_ATTRIB_SLOCK) ||
37 	   !(attrib & HFSP_WRAP_ATTRIB_SPARED))
38 		return 0;
39 
40 	wd->ablk_size = be32_to_cpu(*(__be32 *)(bufptr + HFSP_WRAPOFF_ABLKSIZE));
41 	if (wd->ablk_size < HFSPLUS_SECTOR_SIZE)
42 		return 0;
43 	if (wd->ablk_size % HFSPLUS_SECTOR_SIZE)
44 		return 0;
45 	wd->ablk_start = be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ABLKSTART));
46 
47 	extent = be32_to_cpu(get_unaligned((__be32 *)(bufptr + HFSP_WRAPOFF_EMBEDEXT)));
48 	wd->embed_start = (extent >> 16) & 0xFFFF;
49 	wd->embed_count = extent & 0xFFFF;
50 
51 	return 1;
52 }
53 
54 static int hfsplus_get_last_session(struct super_block *sb,
55 				    sector_t *start, sector_t *size)
56 {
57 	struct cdrom_multisession ms_info;
58 	struct cdrom_tocentry te;
59 	int res;
60 
61 	/* default values */
62 	*start = 0;
63 	*size = sb->s_bdev->bd_inode->i_size >> 9;
64 
65 	if (HFSPLUS_SB(sb).session >= 0) {
66 		te.cdte_track = HFSPLUS_SB(sb).session;
67 		te.cdte_format = CDROM_LBA;
68 		res = ioctl_by_bdev(sb->s_bdev, CDROMREADTOCENTRY, (unsigned long)&te);
69 		if (!res && (te.cdte_ctrl & CDROM_DATA_TRACK) == 4) {
70 			*start = (sector_t)te.cdte_addr.lba << 2;
71 			return 0;
72 		}
73 		printk(KERN_ERR "HFS: Invalid session number or type of track\n");
74 		return -EINVAL;
75 	}
76 	ms_info.addr_format = CDROM_LBA;
77 	res = ioctl_by_bdev(sb->s_bdev, CDROMMULTISESSION, (unsigned long)&ms_info);
78 	if (!res && ms_info.xa_flag)
79 		*start = (sector_t)ms_info.addr.lba << 2;
80 	return 0;
81 }
82 
83 /* Find the volume header and fill in some minimum bits in superblock */
84 /* Takes in super block, returns true if good data read */
85 int hfsplus_read_wrapper(struct super_block *sb)
86 {
87 	struct buffer_head *bh;
88 	struct hfsplus_vh *vhdr;
89 	struct hfsplus_wd wd;
90 	sector_t part_start, part_size;
91 	u32 blocksize;
92 
93 	blocksize = sb_min_blocksize(sb, HFSPLUS_SECTOR_SIZE);
94 	if (!blocksize)
95 		return -EINVAL;
96 
97 	if (hfsplus_get_last_session(sb, &part_start, &part_size))
98 		return -EINVAL;
99 	while (1) {
100 		bh = sb_bread512(sb, part_start + HFSPLUS_VOLHEAD_SECTOR, vhdr);
101 		if (!bh)
102 			return -EIO;
103 
104 		if (vhdr->signature == cpu_to_be16(HFSP_WRAP_MAGIC)) {
105 			if (!hfsplus_read_mdb(vhdr, &wd))
106 				goto error;
107 			wd.ablk_size >>= HFSPLUS_SECTOR_SHIFT;
108 			part_start += wd.ablk_start + wd.embed_start * wd.ablk_size;
109 			part_size = wd.embed_count * wd.ablk_size;
110 			brelse(bh);
111 			bh = sb_bread512(sb, part_start + HFSPLUS_VOLHEAD_SECTOR, vhdr);
112 			if (!bh)
113 				return -EIO;
114 		}
115 		if (vhdr->signature == cpu_to_be16(HFSPLUS_VOLHEAD_SIG))
116 			break;
117 		brelse(bh);
118 
119 		/* check for a partition block
120 		 * (should do this only for cdrom/loop though)
121 		 */
122 		if (hfs_part_find(sb, &part_start, &part_size))
123 			return -EINVAL;
124 	}
125 
126 	blocksize = be32_to_cpu(vhdr->blocksize);
127 	brelse(bh);
128 
129 	/* block size must be at least as large as a sector
130 	 * and a multiple of 2
131 	 */
132 	if (blocksize < HFSPLUS_SECTOR_SIZE ||
133 	    ((blocksize - 1) & blocksize))
134 		return -EINVAL;
135 	HFSPLUS_SB(sb).alloc_blksz = blocksize;
136 	HFSPLUS_SB(sb).alloc_blksz_shift = 0;
137 	while ((blocksize >>= 1) != 0)
138 		HFSPLUS_SB(sb).alloc_blksz_shift++;
139 	blocksize = min(HFSPLUS_SB(sb).alloc_blksz, (u32)PAGE_SIZE);
140 
141 	/* align block size to block offset */
142 	while (part_start & ((blocksize >> HFSPLUS_SECTOR_SHIFT) - 1))
143 		blocksize >>= 1;
144 
145 	if (sb_set_blocksize(sb, blocksize) != blocksize) {
146 		printk("HFS+: unable to blocksize to %u!\n", blocksize);
147 		return -EINVAL;
148 	}
149 
150 	HFSPLUS_SB(sb).blockoffset = part_start >>
151 			(sb->s_blocksize_bits - HFSPLUS_SECTOR_SHIFT);
152 	HFSPLUS_SB(sb).sect_count = part_size;
153 	HFSPLUS_SB(sb).fs_shift = HFSPLUS_SB(sb).alloc_blksz_shift -
154 			sb->s_blocksize_bits;
155 
156 	bh = sb_bread512(sb, part_start + HFSPLUS_VOLHEAD_SECTOR, vhdr);
157 	if (!bh)
158 		return -EIO;
159 
160 	/* should still be the same... */
161 	if (be16_to_cpu(vhdr->signature) != HFSPLUS_VOLHEAD_SIG)
162 		goto error;
163 	HFSPLUS_SB(sb).s_vhbh = bh;
164 	HFSPLUS_SB(sb).s_vhdr = vhdr;
165 
166 	return 0;
167  error:
168 	brelse(bh);
169 	return -EINVAL;
170 }
171