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 <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         __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
  57 static 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 */
  88 int 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 }