[deliverable/linux.git] / fs / hfsplus / part_tbl.c

/*
 * 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, 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 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;

		res = hfsplus_submit_bio(sb->s_bdev,
					 *part_start + HFS_PMAP_BLK + i,
					 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 *data;
	int res;

	data = kmalloc(HFSPLUS_SECTOR_SIZE, GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	res = hfsplus_submit_bio(sb->s_bdev, *part_start + HFS_PMAP_BLK,
				 data, READ);
	if (res)
		return res;

	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, data, part_start, part_size);
		break;
	default:
		res = -ENOENT;
		break;
	}

	kfree(data);
	return res;
}
Commit	Line	Data
1da177e4	1	/*
f30c2269	2	* linux/fs/hfsplus/part_tbl.c
1da177e4 LT	3	*
	4	* Copyright (C) 1996-1997 Paul H. Hargrove
	5	* This file may be distributed under the terms of the GNU General Public License.
	6	*
	7	* Original code to handle the new style Mac partition table based on
	8	* a patch contributed by Holger Schemel (aeglos@valinor.owl.de).
	9	*
	10	* In function preconditions the term "valid" applied to a pointer to
	11	* a structure means that the pointer is non-NULL and the structure it
	12	* points to has all fields initialized to consistent values.
	13	*
	14	*/
	15
358f26d5	16	#include <linux/slab.h>
1da177e4 LT	17	#include "hfsplus_fs.h"
	18
	19	/* offsets to various blocks */
	20	#define HFS_DD_BLK 0 /* Driver Descriptor block */
	21	#define HFS_PMAP_BLK 1 /* First block of partition map */
	22	#define HFS_MDB_BLK 2 /* Block (w/i partition) of MDB */
	23
	24	/* magic numbers for various disk blocks */
	25	#define HFS_DRVR_DESC_MAGIC 0x4552 /* "ER": driver descriptor map */
	26	#define HFS_OLD_PMAP_MAGIC 0x5453 /* "TS": old-type partition map */
	27	#define HFS_NEW_PMAP_MAGIC 0x504D /* "PM": new-type partition map */
	28	#define HFS_SUPER_MAGIC 0x4244 /* "BD": HFS MDB (super block) */
	29	#define HFS_MFS_SUPER_MAGIC 0xD2D7 /* MFS MDB (super block) */
	30
	31	/*
	32	* The new style Mac partition map
	33	*
	34	* For each partition on the media there is a physical block (512-byte
	35	* block) containing one of these structures. These blocks are
	36	* contiguous starting at block 1.
	37	*/
	38	struct new_pmap {
	39	__be16 pmSig; /* signature */
	40	__be16 reSigPad; /* padding */
	41	__be32 pmMapBlkCnt; /* partition blocks count */
	42	__be32 pmPyPartStart; /* physical block start of partition */
	43	__be32 pmPartBlkCnt; /* physical block count of partition */
	44	u8 pmPartName[32]; /* (null terminated?) string
	45	giving the name of this
	46	partition */
	47	u8 pmPartType[32]; /* (null terminated?) string
	48	giving the type of this
	49	partition */
	50	/* a bunch more stuff we don't need */
	51	} __packed;
	52
	53	/*
	54	* The old style Mac partition map
	55	*
	56	* The partition map consists for a 2-byte signature followed by an
	57	* array of these structures. The map is terminated with an all-zero
	58	* one of these.
	59	*/
	60	struct old_pmap {
	61	__be16 pdSig; /* Signature bytes */
	62	struct old_pmap_entry {
	63	__be32 pdStart;
	64	__be32 pdSize;
	65	__be32 pdFSID;
	66	} pdEntry[42];
	67	} __packed;
	68
358f26d5 CH	69	static int hfs_parse_old_pmap(struct super_block sb, struct old_pmap pm,
	70	sector_t part_start, sector_t part_size)
	71	{
	72	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
	73	int i;
	74
	75	for (i = 0; i < 42; i++) {
	76	struct old_pmap_entry *p = &pm->pdEntry[i];
	77
	78	if (p->pdStart && p->pdSize &&
	79	p->pdFSID == cpu_to_be32(0x54465331)/"TFS1"/ &&
	80	(sbi->part < 0 \|\| sbi->part == i)) {
	81	*part_start += be32_to_cpu(p->pdStart);
	82	*part_size = be32_to_cpu(p->pdSize);
	83	return 0;
	84	}
	85	}
	86
	87	return -ENOENT;
	88	}
	89
	90	static int hfs_parse_new_pmap(struct super_block sb, struct new_pmap pm,
	91	sector_t part_start, sector_t part_size)
	92	{
	93	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
	94	int size = be32_to_cpu(pm->pmMapBlkCnt);
	95	int res;
	96	int i = 0;
	97
	98	do {
	99	if (!memcmp(pm->pmPartType,"Apple_HFS", 9) &&
	100	(sbi->part < 0 \|\| sbi->part == i)) {
	101	*part_start += be32_to_cpu(pm->pmPyPartStart);
	102	*part_size = be32_to_cpu(pm->pmPartBlkCnt);
	103	return 0;
	104	}
	105
	106	if (++i >= size)
	107	return -ENOENT;
	108
	109	res = hfsplus_submit_bio(sb->s_bdev,
	110	*part_start + HFS_PMAP_BLK + i,
	111	pm, READ);
	112	if (res)
	113	return res;
	114	} while (pm->pmSig == cpu_to_be16(HFS_NEW_PMAP_MAGIC));
	115
	116	return -ENOENT;
	117	}
	118
1da177e4	119	/*
358f26d5 CH	120	* Parse the partition map looking for the start and length of a
358f26d5 CH	121	* HFS/HFS+ partition.
1da177e4 LT	122	*/
1da177e4 LT	123	int hfs_part_find(struct super_block *sb,
358f26d5	124	sector_t part_start, sector_t part_size)
1da177e4	125	{
358f26d5 CH	126	void *data;
	127	int res;
	128
	129	data = kmalloc(HFSPLUS_SECTOR_SIZE, GFP_KERNEL);
	130	if (!data)
	131	return -ENOMEM;
1da177e4	132
358f26d5 CH	133	res = hfsplus_submit_bio(sb->s_bdev, *part_start + HFS_PMAP_BLK,
	134	data, READ);
	135	if (res)
	136	return res;
1da177e4	137
358f26d5	138	switch (be16_to_cpu(((__be16 )data))) {
1da177e4	139	case HFS_OLD_PMAP_MAGIC:
358f26d5	140	res = hfs_parse_old_pmap(sb, data, part_start, part_size);
1da177e4	141	break;
1da177e4	142	case HFS_NEW_PMAP_MAGIC:
358f26d5 CH	143	res = hfs_parse_new_pmap(sb, data, part_start, part_size);
	144	break;
	145	default:
	146	res = -ENOENT;
1da177e4	147	break;
1da177e4	148	}
1da177e4	149
358f26d5	150	kfree(data);
1da177e4 LT	151	return res;
1da177e4 LT	152	}