159 lines
4.2 KiB
C
159 lines
4.2 KiB
C
/*
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* linux/fs/hfsplus/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
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* 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 <linux/slab.h>
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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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static int hfs_parse_old_pmap(struct super_block *sb, struct old_pmap *pm,
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sector_t *part_start, sector_t *part_size)
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{
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struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
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int i;
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for (i = 0; i < 42; i++) {
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struct old_pmap_entry *p = &pm->pdEntry[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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(sbi->part < 0 || sbi->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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return 0;
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}
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}
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return -ENOENT;
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}
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static int hfs_parse_new_pmap(struct super_block *sb, void *buf,
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struct new_pmap *pm, sector_t *part_start, sector_t *part_size)
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{
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struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
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int size = be32_to_cpu(pm->pmMapBlkCnt);
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int buf_size = hfsplus_min_io_size(sb);
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int res;
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int i = 0;
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do {
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if (!memcmp(pm->pmPartType, "Apple_HFS", 9) &&
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(sbi->part < 0 || sbi->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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return 0;
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}
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if (++i >= size)
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return -ENOENT;
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pm = (struct new_pmap *)((u8 *)pm + HFSPLUS_SECTOR_SIZE);
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if ((u8 *)pm - (u8 *)buf >= buf_size) {
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res = hfsplus_submit_bio(sb,
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*part_start + HFS_PMAP_BLK + i,
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buf, (void **)&pm, REQ_OP_READ,
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0);
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if (res)
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return res;
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}
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} while (pm->pmSig == cpu_to_be16(HFS_NEW_PMAP_MAGIC));
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return -ENOENT;
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}
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/*
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* Parse the partition map looking for the start and length of a
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* HFS/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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void *buf, *data;
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int res;
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buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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res = hfsplus_submit_bio(sb, *part_start + HFS_PMAP_BLK,
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buf, &data, REQ_OP_READ, 0);
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if (res)
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goto out;
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switch (be16_to_cpu(*((__be16 *)data))) {
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case HFS_OLD_PMAP_MAGIC:
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res = hfs_parse_old_pmap(sb, data, part_start, part_size);
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break;
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case HFS_NEW_PMAP_MAGIC:
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res = hfs_parse_new_pmap(sb, buf, data, part_start, part_size);
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break;
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default:
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res = -ENOENT;
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break;
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}
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out:
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kfree(buf);
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return res;
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}
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