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1275 |
phoenix |
/*
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* linux/fs/hfsplus/wrapper.c
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*
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* Copyright (C) 2001
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* Brad Boyer (flar@allandria.com)
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* (C) 2003 Ardis Technologies <roman@ardistech.com>
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*
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* Handling of HFS wrappers around HFS+ volumes
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*/
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#include <linux/fs.h>
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#include <linux/blkdev.h>
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#include <linux/version.h>
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#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,5,0)
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#include <linux/buffer_head.h>
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#endif
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#include <asm/unaligned.h>
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#include "hfsplus_fs.h"
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#include "hfsplus_raw.h"
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struct hfsplus_wd {
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u32 ablk_size;
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u16 ablk_start;
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u16 embed_start;
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u16 embed_count;
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};
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static int hfsplus_read_mdb(unsigned char *bufptr, struct hfsplus_wd *wd)
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{
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u32 extent;
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u16 attrib;
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if (be16_to_cpu(*(u16 *)(bufptr + HFSP_WRAPOFF_EMBEDSIG)) != HFSPLUS_VOLHEAD_SIG)
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return 0;
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attrib = be16_to_cpu(*(u16 *)(bufptr + HFSP_WRAPOFF_ATTRIB));
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if (!(attrib & HFSP_WRAP_ATTRIB_SLOCK) ||
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!(attrib & HFSP_WRAP_ATTRIB_SPARED))
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return 0;
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wd->ablk_size = be32_to_cpu(*(u32 *)(bufptr + HFSP_WRAPOFF_ABLKSIZE));
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if (wd->ablk_size < HFSPLUS_SECTOR_SIZE)
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return 0;
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if (wd->ablk_size % HFSPLUS_SECTOR_SIZE)
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return 0;
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wd->ablk_start = be16_to_cpu(*(u16 *)(bufptr + HFSP_WRAPOFF_ABLKSTART));
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extent = be32_to_cpu(get_unaligned((u32 *)(bufptr + HFSP_WRAPOFF_EMBEDEXT)));
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wd->embed_start = (extent >> 16) & 0xFFFF;
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wd->embed_count = extent & 0xFFFF;
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return 1;
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}
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/* Find the volume header and fill in some minimum bits in superblock */
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/* Takes in super block, returns true if good data read */
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int hfsplus_read_wrapper(struct super_block *sb)
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{
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struct buffer_head *bh;
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struct hfsplus_vh *vhdr;
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char *bufptr;
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unsigned long block, offset, vhsect;
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struct hfsplus_wd wd;
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u32 blocksize, blockoffset;
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u16 sig;
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blocksize = sb_min_blocksize(sb, HFSPLUS_SECTOR_SIZE);
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if (!blocksize) {
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printk("HFS+-fs: unable to configure block size\n");
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return -EINVAL;
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}
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block = (HFSPLUS_VOLHEAD_SECTOR * HFSPLUS_SECTOR_SIZE) / blocksize;
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offset = (HFSPLUS_VOLHEAD_SECTOR * HFSPLUS_SECTOR_SIZE) % blocksize;
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bh = sb_bread(sb, block);
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if (!bh) {
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printk("HFS+-fs: unable to read VHDR or MDB\n");
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return -EIO;
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}
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bufptr = bh->b_data + offset;
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sig = be16_to_cpu(*(u16 *)(bufptr + HFSP_WRAPOFF_SIG));
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if (sig == HFSP_WRAP_MAGIC) {
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if (!hfsplus_read_mdb(bufptr, &wd))
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goto error;
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vhsect = (wd.ablk_start + wd.embed_start * (wd.ablk_size >> 9))
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+ HFSPLUS_VOLHEAD_SECTOR;
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block = (vhsect * HFSPLUS_SECTOR_SIZE) / blocksize;
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offset = (vhsect * HFSPLUS_SECTOR_SIZE) % blocksize;
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brelse(bh);
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bh = sb_bread(sb, block);
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if (!bh) {
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printk("HFS+-fs: unable to read VHDR\n");
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return -EIO;
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}
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HFSPLUS_SB(sb).sect_count = wd.embed_count * (wd.ablk_size >> 9);
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} else {
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wd.ablk_start = 0;
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wd.ablk_size = blocksize;
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wd.embed_start = 0;
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HFSPLUS_SB(sb).sect_count = sb->s_bdev->bd_inode->i_size >> 9;
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}
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vhdr = (struct hfsplus_vh *)(bh->b_data + offset);
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if (be16_to_cpu(vhdr->signature) != HFSPLUS_VOLHEAD_SIG)
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goto error;
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blocksize = be32_to_cpu(vhdr->blocksize);
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brelse(bh);
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/* block size must be at least as large as a sector
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* and a multiple of 2
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*/
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if (blocksize < HFSPLUS_SECTOR_SIZE ||
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((blocksize - 1) & blocksize))
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return -EINVAL;
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/* block offset must be a multiple of the block size */
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blockoffset = wd.ablk_start + wd.embed_start * (wd.ablk_size >> 9);
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if (blockoffset % (blocksize / HFSPLUS_SECTOR_SIZE)) {
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printk("HFS+-fs: embedded blocks not aligned with wrapper\n");
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return -EINVAL;
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}
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blockoffset /= blocksize / HFSPLUS_SECTOR_SIZE;
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HFSPLUS_SB(sb).blockoffset = blockoffset;
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if (sb_set_blocksize(sb, blocksize) != blocksize)
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return -EINVAL;
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block = blockoffset + HFSPLUS_VOLHEAD_SECTOR /
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(blocksize / HFSPLUS_SECTOR_SIZE);
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offset = (HFSPLUS_VOLHEAD_SECTOR * HFSPLUS_SECTOR_SIZE) % blocksize;
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bh = sb_bread(sb, block);
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if (!bh) {
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printk("HFS+-fs: unable to read VHDR or MDB\n");
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return -EIO;
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}
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vhdr = (struct hfsplus_vh *)(bh->b_data + offset);
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/* should still be the same... */
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if (be16_to_cpu(vhdr->signature) != HFSPLUS_VOLHEAD_SIG)
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goto error;
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HFSPLUS_SB(sb).s_vhbh = bh;
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HFSPLUS_SB(sb).s_vhdr = vhdr;
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return 0;
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error:
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brelse(bh);
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return -EINVAL;
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}
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