fs/hfsplus/wrapper.c

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