[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 ([email protected]).
 *
 * 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 "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;

/*
 * hfs_part_find()
 *
 * Parse the partition map looking for the
 * start and length of the 'part'th HFS partition.
 */
int hfs_part_find(struct super_block *sb,
		  sector_t *part_start, sector_t *part_size)
{
	struct buffer_head *bh;
	__be16 *data;
	int i, size, res;

	res = -ENOENT;
	bh = sb_bread512(sb, *part_start + HFS_PMAP_BLK, data);
	if (!bh)
		return -EIO;

	switch (be16_to_cpu(*data)) {
	case HFS_OLD_PMAP_MAGIC:
	  {
		struct old_pmap *pm;
		struct old_pmap_entry *p;

		pm = (struct old_pmap *)bh->b_data;
		p = pm->pdEntry;
		size = 42;
		for (i = 0; i < size; p++, i++) {
			if (p->pdStart && p->pdSize &&
			    p->pdFSID == cpu_to_be32(0x54465331)/*"TFS1"*/ &&
			    (HFSPLUS_SB(sb).part < 0 || HFSPLUS_SB(sb).part == i)) {
				*part_start += be32_to_cpu(p->pdStart);
				*part_size = be32_to_cpu(p->pdSize);
				res = 0;
			}
		}
		break;
	  }
	case HFS_NEW_PMAP_MAGIC:
	  {
		struct new_pmap *pm;

		pm = (struct new_pmap *)bh->b_data;
		size = be32_to_cpu(pm->pmMapBlkCnt);
		for (i = 0; i < size;) {
			if (!memcmp(pm->pmPartType,"Apple_HFS", 9) &&
			    (HFSPLUS_SB(sb).part < 0 || HFSPLUS_SB(sb).part == i)) {
				*part_start += be32_to_cpu(pm->pmPyPartStart);
				*part_size = be32_to_cpu(pm->pmPartBlkCnt);
				res = 0;
				break;
			}
			brelse(bh);
			bh = sb_bread512(sb, *part_start + HFS_PMAP_BLK + ++i, pm);
			if (!bh)
				return -EIO;
			if (pm->pmSig != cpu_to_be16(HFS_NEW_PMAP_MAGIC))
				break;
		}
		break;
	  }
	}
	brelse(bh);

	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 ([email protected]).
	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
	16	#include "hfsplus_fs.h"
	17
	18	/* offsets to various blocks */
	19	#define HFS_DD_BLK 0 /* Driver Descriptor block */
	20	#define HFS_PMAP_BLK 1 /* First block of partition map */
	21	#define HFS_MDB_BLK 2 /* Block (w/i partition) of MDB */
	22
	23	/* magic numbers for various disk blocks */
	24	#define HFS_DRVR_DESC_MAGIC 0x4552 /* "ER": driver descriptor map */
	25	#define HFS_OLD_PMAP_MAGIC 0x5453 /* "TS": old-type partition map */
	26	#define HFS_NEW_PMAP_MAGIC 0x504D /* "PM": new-type partition map */
	27	#define HFS_SUPER_MAGIC 0x4244 /* "BD": HFS MDB (super block) */
	28	#define HFS_MFS_SUPER_MAGIC 0xD2D7 /* MFS MDB (super block) */
	29
	30	/*
	31	* The new style Mac partition map
	32	*
	33	* For each partition on the media there is a physical block (512-byte
	34	* block) containing one of these structures. These blocks are
	35	* contiguous starting at block 1.
	36	*/
	37	struct new_pmap {
	38	__be16 pmSig; /* signature */
	39	__be16 reSigPad; /* padding */
	40	__be32 pmMapBlkCnt; /* partition blocks count */
	41	__be32 pmPyPartStart; /* physical block start of partition */
	42	__be32 pmPartBlkCnt; /* physical block count of partition */
	43	u8 pmPartName[32]; /* (null terminated?) string
	44	giving the name of this
	45	partition */
	46	u8 pmPartType[32]; /* (null terminated?) string
	47	giving the type of this
	48	partition */
	49	/* a bunch more stuff we don't need */
	50	} __packed;
	51
	52	/*
	53	* The old style Mac partition map
	54	*
	55	* The partition map consists for a 2-byte signature followed by an
	56	* array of these structures. The map is terminated with an all-zero
	57	* one of these.
	58	*/
	59	struct old_pmap {
	60	__be16 pdSig; /* Signature bytes */
	61	struct old_pmap_entry {
	62	__be32 pdStart;
	63	__be32 pdSize;
	64	__be32 pdFSID;
	65	} pdEntry[42];
	66	} __packed;
67
68	/*
69	* hfs_part_find()
70	*
71	* Parse the partition map looking for the
72	* start and length of the 'part'th HFS partition.
73	*/
74	int hfs_part_find(struct super_block *sb,
75	sector_t part_start, sector_t part_size)
76	{
77	struct buffer_head *bh;
78	__be16 *data;
79	int i, size, res;
80
81	res = -ENOENT;
82	bh = sb_bread512(sb, *part_start + HFS_PMAP_BLK, data);
83	if (!bh)
84	return -EIO;
85
86	switch (be16_to_cpu(*data)) {
87	case HFS_OLD_PMAP_MAGIC:
88	{
89	struct old_pmap *pm;
90	struct old_pmap_entry *p;
91
92	pm = (struct old_pmap *)bh->b_data;
93	p = pm->pdEntry;
94	size = 42;
95	for (i = 0; i < size; p++, i++) {
96	if (p->pdStart && p->pdSize &&
97	p->pdFSID == cpu_to_be32(0x54465331)/"TFS1"/ &&
98	(HFSPLUS_SB(sb).part < 0 \|\| HFSPLUS_SB(sb).part == i)) {
99	*part_start += be32_to_cpu(p->pdStart);
100	*part_size = be32_to_cpu(p->pdSize);
101	res = 0;
102	}
103	}
104	break;
105	}
106	case HFS_NEW_PMAP_MAGIC:
107	{
108	struct new_pmap *pm;
109
110	pm = (struct new_pmap *)bh->b_data;
111	size = be32_to_cpu(pm->pmMapBlkCnt);
112	for (i = 0; i < size;) {
113	if (!memcmp(pm->pmPartType,"Apple_HFS", 9) &&
114	(HFSPLUS_SB(sb).part < 0 \|\| HFSPLUS_SB(sb).part == i)) {
115	*part_start += be32_to_cpu(pm->pmPyPartStart);
116	*part_size = be32_to_cpu(pm->pmPartBlkCnt);
117	res = 0;
118	break;
119	}
120	brelse(bh);
121	bh = sb_bread512(sb, *part_start + HFS_PMAP_BLK + ++i, pm);
122	if (!bh)
123	return -EIO;
124	if (pm->pmSig != cpu_to_be16(HFS_NEW_PMAP_MAGIC))
125	break;
126	}
127	break;
128	}
129	}
130	brelse(bh);
131
132	return res;
133	}