LXR linux/fs/hfs/part

   1/*
   2 *  linux/fs/hfs/part_tbl.c
   3 *
   4 * Copyright (C) 1996-1997  Paul H. Hargrove
   5 * (C) 2003 Ardis Technologies <roman@ardistech.com>
   6 * This file may be distributed under the terms of the GNU General Public License.
   7 *
   8 * Original code to handle the new style Mac partition table based on
   9 * a patch contributed by Holger Schemel (aeglos@valinor.owl.de).
  10 */
  11
  12#include "hfs_fs.h"
  13
  14/*
  15 * The new style Mac partition map
  16 *
  17 * For each partition on the media there is a physical block (512-byte
  18 * block) containing one of these structures.  These blocks are
  19 * contiguous starting at block 1.
  20 */
  21struct new_pmap {
  22        __be16  pmSig;          /* signature */
  23        __be16  reSigPad;       /* padding */
  24        __be32  pmMapBlkCnt;    /* partition blocks count */
  25        __be32  pmPyPartStart;  /* physical block start of partition */
  26        __be32  pmPartBlkCnt;   /* physical block count of partition */
  27        u8      pmPartName[32]; /* (null terminated?) string
  28                                   giving the name of this
  29                                   partition */
  30        u8      pmPartType[32]; /* (null terminated?) string
  31                                   giving the type of this
  32                                   partition */
  33        /* a bunch more stuff we don't need */
  34} __packed;
  35
  36/*
  37 * The old style Mac partition map
  38 *
  39 * The partition map consists for a 2-byte signature followed by an
  40 * array of these structures.  The map is terminated with an all-zero
  41 * one of these.
  42 */
  43struct old_pmap {
  44        __be16          pdSig;  /* Signature bytes */
  45        struct  old_pmap_entry {
  46                __be32  pdStart;
  47                __be32  pdSize;
  48                __be32  pdFSID;
  49        }       pdEntry[42];
  50} __packed;
  51
  52/*
  53 * hfs_part_find()
  54 *
  55 * Parse the partition map looking for the
  56 * start and length of the 'part'th HFS partition.
  57 */
  58int hfs_part_find(struct super_block *sb,
  59                  sector_t *part_start, sector_t *part_size)
  60{
  61        struct buffer_head *bh;
  62        __be16 *data;
  63        int i, size, res;
  64
  65        res = -ENOENT;
  66        bh = sb_bread512(sb, *part_start + HFS_PMAP_BLK, data);
  67        if (!bh)
  68                return -EIO;
  69
  70        switch (be16_to_cpu(*data)) {
  71        case HFS_OLD_PMAP_MAGIC:
  72          {
  73                struct old_pmap *pm;
  74                struct old_pmap_entry *p;
  75
  76                pm = (struct old_pmap *)bh->b_data;
  77                p = pm->pdEntry;
  78                size = 42;
  79                for (i = 0; i < size; p++, i++) {
  80                        if (p->pdStart && p->pdSize &&
  81                            p->pdFSID == cpu_to_be32(0x54465331)/*"TFS1"*/ &&
  82                            (HFS_SB(sb)->part < 0 || HFS_SB(sb)->part == i)) {
  83                                *part_start += be32_to_cpu(p->pdStart);
  84                                *part_size = be32_to_cpu(p->pdSize);
  85                                res = 0;
  86                        }
  87                }
  88                break;
  89          }
  90        case HFS_NEW_PMAP_MAGIC:
  91          {
  92                struct new_pmap *pm;
  93
  94                pm = (struct new_pmap *)bh->b_data;
  95                size = be32_to_cpu(pm->pmMapBlkCnt);
  96                for (i = 0; i < size;) {
  97                        if (!memcmp(pm->pmPartType,"Apple_HFS", 9) &&
  98                            (HFS_SB(sb)->part < 0 || HFS_SB(sb)->part == i)) {
  99                                *part_start += be32_to_cpu(pm->pmPyPartStart);
 100                                *part_size = be32_to_cpu(pm->pmPartBlkCnt);
 101                                res = 0;
 102                                break;
 103                        }
 104                        brelse(bh);
 105                        bh = sb_bread512(sb, *part_start + HFS_PMAP_BLK + ++i, pm);
 106                        if (!bh)
 107                                return -EIO;
 108                        if (pm->pmSig != cpu_to_be16(HFS_NEW_PMAP_MAGIC))
 109                                break;
 110                }
 111                break;
 112          }
 113        }
 114        brelse(bh);
 115
 116        return res;
 117}
 118