diff options
Diffstat (limited to 'fs/hfsplus/part_tbl.c')
| -rw-r--r-- | fs/hfsplus/part_tbl.c | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/fs/hfsplus/part_tbl.c b/fs/hfsplus/part_tbl.c new file mode 100644 index 000000000..eb355d81e --- /dev/null +++ b/fs/hfsplus/part_tbl.c @@ -0,0 +1,157 @@ +/* + * linux/fs/hfsplus/part_tbl.c + * + * Copyright (C) 1996-1997 Paul H. Hargrove + * This file may be distributed under the terms of + * the GNU General Public License. + * + * Original code to handle the new style Mac partition table based on + * a patch contributed by Holger Schemel (aeglos@valinor.owl.de). + * + * In function preconditions the term "valid" applied to a pointer to + * a structure means that the pointer is non-NULL and the structure it + * points to has all fields initialized to consistent values. + * + */ + +#include <linux/slab.h> +#include "hfsplus_fs.h" + +/* offsets to various blocks */ +#define HFS_DD_BLK 0 /* Driver Descriptor block */ +#define HFS_PMAP_BLK 1 /* First block of partition map */ +#define HFS_MDB_BLK 2 /* Block (w/i partition) of MDB */ + +/* magic numbers for various disk blocks */ +#define HFS_DRVR_DESC_MAGIC 0x4552 /* "ER": driver descriptor map */ +#define HFS_OLD_PMAP_MAGIC 0x5453 /* "TS": old-type partition map */ +#define HFS_NEW_PMAP_MAGIC 0x504D /* "PM": new-type partition map */ +#define HFS_SUPER_MAGIC 0x4244 /* "BD": HFS MDB (super block) */ +#define HFS_MFS_SUPER_MAGIC 0xD2D7 /* MFS MDB (super block) */ + +/* + * The new style Mac partition map + * + * For each partition on the media there is a physical block (512-byte + * block) containing one of these structures. These blocks are + * contiguous starting at block 1. + */ +struct new_pmap { + __be16 pmSig; /* signature */ + __be16 reSigPad; /* padding */ + __be32 pmMapBlkCnt; /* partition blocks count */ + __be32 pmPyPartStart; /* physical block start of partition */ + __be32 pmPartBlkCnt; /* physical block count of partition */ + u8 pmPartName[32]; /* (null terminated?) string + giving the name of this + partition */ + u8 pmPartType[32]; /* (null terminated?) string + giving the type of this + partition */ + /* a bunch more stuff we don't need */ +} __packed; + +/* + * The old style Mac partition map + * + * The partition map consists for a 2-byte signature followed by an + * array of these structures. The map is terminated with an all-zero + * one of these. + */ +struct old_pmap { + __be16 pdSig; /* Signature bytes */ + struct old_pmap_entry { + __be32 pdStart; + __be32 pdSize; + __be32 pdFSID; + } pdEntry[42]; +} __packed; + +static int hfs_parse_old_pmap(struct super_block *sb, struct old_pmap *pm, + sector_t *part_start, sector_t *part_size) +{ + struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb); + int i; + + for (i = 0; i < 42; i++) { + struct old_pmap_entry *p = &pm->pdEntry[i]; + + if (p->pdStart && p->pdSize && + p->pdFSID == cpu_to_be32(0x54465331)/*"TFS1"*/ && + (sbi->part < 0 || sbi->part == i)) { + *part_start += be32_to_cpu(p->pdStart); + *part_size = be32_to_cpu(p->pdSize); + return 0; + } + } + + return -ENOENT; +} + +static int hfs_parse_new_pmap(struct super_block *sb, void *buf, + struct new_pmap *pm, sector_t *part_start, sector_t *part_size) +{ + struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb); + int size = be32_to_cpu(pm->pmMapBlkCnt); + int buf_size = hfsplus_min_io_size(sb); + int res; + int i = 0; + + do { + if (!memcmp(pm->pmPartType, "Apple_HFS", 9) && + (sbi->part < 0 || sbi->part == i)) { + *part_start += be32_to_cpu(pm->pmPyPartStart); + *part_size = be32_to_cpu(pm->pmPartBlkCnt); + return 0; + } + + if (++i >= size) + return -ENOENT; + + pm = (struct new_pmap *)((u8 *)pm + HFSPLUS_SECTOR_SIZE); + if ((u8 *)pm - (u8 *)buf >= buf_size) { + res = hfsplus_submit_bio(sb, + *part_start + HFS_PMAP_BLK + i, + buf, (void **)&pm, READ); + if (res) + return res; + } + } while (pm->pmSig == cpu_to_be16(HFS_NEW_PMAP_MAGIC)); + + return -ENOENT; +} + +/* + * Parse the partition map looking for the start and length of a + * HFS/HFS+ partition. + */ +int hfs_part_find(struct super_block *sb, + sector_t *part_start, sector_t *part_size) +{ + void *buf, *data; + int res; + + buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL); + if (!buf) + return -ENOMEM; + + res = hfsplus_submit_bio(sb, *part_start + HFS_PMAP_BLK, + buf, &data, READ); + if (res) + goto out; + + switch (be16_to_cpu(*((__be16 *)data))) { + case HFS_OLD_PMAP_MAGIC: + res = hfs_parse_old_pmap(sb, data, part_start, part_size); + break; + case HFS_NEW_PMAP_MAGIC: + res = hfs_parse_new_pmap(sb, buf, data, part_start, part_size); + break; + default: + res = -ENOENT; + break; + } +out: + kfree(buf); + return res; +} |