134 lines
3.6 KiB
C
134 lines
3.6 KiB
C
/*
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* linux/fs/hfs/part_tbl.c
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*
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* Copyright (C) 1996-1997 Paul H. Hargrove
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* This file may be distributed under the terms of the GNU General Public License.
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*
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* Original code to handle the new style Mac partition table based on
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* a patch contributed by Holger Schemel (aeglos@valinor.owl.de).
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*
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* In function preconditions the term "valid" applied to a pointer to
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* a structure means that the pointer is non-NULL and the structure it
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* points to has all fields initialized to consistent values.
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*
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*/
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#include "hfsplus_fs.h"
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/* offsets to various blocks */
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#define HFS_DD_BLK 0 /* Driver Descriptor block */
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#define HFS_PMAP_BLK 1 /* First block of partition map */
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#define HFS_MDB_BLK 2 /* Block (w/i partition) of MDB */
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/* magic numbers for various disk blocks */
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#define HFS_DRVR_DESC_MAGIC 0x4552 /* "ER": driver descriptor map */
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#define HFS_OLD_PMAP_MAGIC 0x5453 /* "TS": old-type partition map */
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#define HFS_NEW_PMAP_MAGIC 0x504D /* "PM": new-type partition map */
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#define HFS_SUPER_MAGIC 0x4244 /* "BD": HFS MDB (super block) */
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#define HFS_MFS_SUPER_MAGIC 0xD2D7 /* MFS MDB (super block) */
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/*
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* The new style Mac partition map
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*
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* For each partition on the media there is a physical block (512-byte
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* block) containing one of these structures. These blocks are
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* contiguous starting at block 1.
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*/
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struct new_pmap {
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__be16 pmSig; /* signature */
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__be16 reSigPad; /* padding */
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__be32 pmMapBlkCnt; /* partition blocks count */
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__be32 pmPyPartStart; /* physical block start of partition */
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__be32 pmPartBlkCnt; /* physical block count of partition */
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u8 pmPartName[32]; /* (null terminated?) string
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giving the name of this
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partition */
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u8 pmPartType[32]; /* (null terminated?) string
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giving the type of this
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partition */
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/* a bunch more stuff we don't need */
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} __packed;
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/*
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* The old style Mac partition map
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*
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* The partition map consists for a 2-byte signature followed by an
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* array of these structures. The map is terminated with an all-zero
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* one of these.
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*/
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struct old_pmap {
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__be16 pdSig; /* Signature bytes */
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struct old_pmap_entry {
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__be32 pdStart;
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__be32 pdSize;
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__be32 pdFSID;
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} pdEntry[42];
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} __packed;
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/*
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* hfs_part_find()
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*
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* Parse the partition map looking for the
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* start and length of the 'part'th HFS partition.
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*/
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int hfs_part_find(struct super_block *sb,
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sector_t *part_start, sector_t *part_size)
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{
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struct buffer_head *bh;
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__be16 *data;
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int i, size, res;
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res = -ENOENT;
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bh = sb_bread512(sb, *part_start + HFS_PMAP_BLK, data);
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if (!bh)
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return -EIO;
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switch (be16_to_cpu(*data)) {
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case HFS_OLD_PMAP_MAGIC:
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{
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struct old_pmap *pm;
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struct old_pmap_entry *p;
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pm = (struct old_pmap *)bh->b_data;
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p = pm->pdEntry;
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size = 42;
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for (i = 0; i < size; p++, i++) {
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if (p->pdStart && p->pdSize &&
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p->pdFSID == cpu_to_be32(0x54465331)/*"TFS1"*/ &&
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(HFSPLUS_SB(sb).part < 0 || HFSPLUS_SB(sb).part == i)) {
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*part_start += be32_to_cpu(p->pdStart);
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*part_size = be32_to_cpu(p->pdSize);
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res = 0;
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}
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}
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break;
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}
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case HFS_NEW_PMAP_MAGIC:
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{
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struct new_pmap *pm;
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pm = (struct new_pmap *)bh->b_data;
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size = be32_to_cpu(pm->pmMapBlkCnt);
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for (i = 0; i < size;) {
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if (!memcmp(pm->pmPartType,"Apple_HFS", 9) &&
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(HFSPLUS_SB(sb).part < 0 || HFSPLUS_SB(sb).part == i)) {
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*part_start += be32_to_cpu(pm->pmPyPartStart);
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*part_size = be32_to_cpu(pm->pmPartBlkCnt);
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res = 0;
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break;
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}
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brelse(bh);
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bh = sb_bread512(sb, *part_start + HFS_PMAP_BLK + ++i, pm);
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if (!bh)
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return -EIO;
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if (pm->pmSig != cpu_to_be16(HFS_NEW_PMAP_MAGIC))
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break;
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}
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break;
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}
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}
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brelse(bh);
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return res;
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}
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