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/*
* 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/version.h>
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,5,0)
#include <linux/buffer_head.h>
#endif
#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(unsigned char *bufptr, struct hfsplus_wd *wd)
{
u32 extent;
u16 attrib;
if (be16_to_cpu(*(u16 *)(bufptr + HFSP_WRAPOFF_EMBEDSIG)) != HFSPLUS_VOLHEAD_SIG)
return 0;
attrib = be16_to_cpu(*(u16 *)(bufptr + HFSP_WRAPOFF_ATTRIB));
if (!(attrib & HFSP_WRAP_ATTRIB_SLOCK) ||
!(attrib & HFSP_WRAP_ATTRIB_SPARED))
return 0;
wd->ablk_size = be32_to_cpu(*(u32 *)(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(*(u16 *)(bufptr + HFSP_WRAPOFF_ABLKSTART));
extent = be32_to_cpu(get_unaligned((u32 *)(bufptr + HFSP_WRAPOFF_EMBEDEXT)));
wd->embed_start = (extent >> 16) & 0xFFFF;
wd->embed_count = extent & 0xFFFF;
return 1;
}
/* 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;
char *bufptr;
unsigned long block, offset, vhsect;
struct hfsplus_wd wd;
u32 blocksize, blockoffset;
u16 sig;
blocksize = sb_min_blocksize(sb, HFSPLUS_SECTOR_SIZE);
if (!blocksize) {
printk("HFS+-fs: unable to configure block size\n");
return -EINVAL;
}
block = (HFSPLUS_VOLHEAD_SECTOR * HFSPLUS_SECTOR_SIZE) / blocksize;
offset = (HFSPLUS_VOLHEAD_SECTOR * HFSPLUS_SECTOR_SIZE) % blocksize;
bh = sb_bread(sb, block);
if (!bh) {
printk("HFS+-fs: unable to read VHDR or MDB\n");
return -EIO;
}
bufptr = bh->b_data + offset;
sig = be16_to_cpu(*(u16 *)(bufptr + HFSP_WRAPOFF_SIG));
if (sig == HFSP_WRAP_MAGIC) {
if (!hfsplus_read_mdb(bufptr, &wd))
goto error;
vhsect = (wd.ablk_start + wd.embed_start * (wd.ablk_size >> 9))
+ HFSPLUS_VOLHEAD_SECTOR;
block = (vhsect * HFSPLUS_SECTOR_SIZE) / blocksize;
offset = (vhsect * HFSPLUS_SECTOR_SIZE) % blocksize;
brelse(bh);
bh = sb_bread(sb, block);
if (!bh) {
printk("HFS+-fs: unable to read VHDR\n");
return -EIO;
}
HFSPLUS_SB(sb).sect_count = wd.embed_count * (wd.ablk_size >> 9);
} else {
wd.ablk_start = 0;
wd.ablk_size = blocksize;
wd.embed_start = 0;
HFSPLUS_SB(sb).sect_count = sb->s_bdev->bd_inode->i_size >> 9;
}
vhdr = (struct hfsplus_vh *)(bh->b_data + offset);
if (be16_to_cpu(vhdr->signature) != HFSPLUS_VOLHEAD_SIG)
goto error;
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;
/* block offset must be a multiple of the block size */
blockoffset = wd.ablk_start + wd.embed_start * (wd.ablk_size >> 9);
if (blockoffset % (blocksize / HFSPLUS_SECTOR_SIZE)) {
printk("HFS+-fs: embedded blocks not aligned with wrapper\n");
return -EINVAL;
}
blockoffset /= blocksize / HFSPLUS_SECTOR_SIZE;
HFSPLUS_SB(sb).blockoffset = blockoffset;
if (sb_set_blocksize(sb, blocksize) != blocksize)
return -EINVAL;
block = blockoffset + HFSPLUS_VOLHEAD_SECTOR /
(blocksize / HFSPLUS_SECTOR_SIZE);
offset = (HFSPLUS_VOLHEAD_SECTOR * HFSPLUS_SECTOR_SIZE) % blocksize;
bh = sb_bread(sb, block);
if (!bh) {
printk("HFS+-fs: unable to read VHDR or MDB\n");
return -EIO;
}
vhdr = (struct hfsplus_vh *)(bh->b_data + offset);
/* 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;
}
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