1 /* 2 * linux/fs/hfsplus/part_tbl.c 3 * 4 * Copyright (C) 1996-1997 Paul H. Hargrove 5 * This file may be distributed under the terms of 6 * the GNU General Public License. 7 * 8 * Original code to handle the new style Mac partition table based on 9 * a patch contributed by Holger Schemel (aeglos@valinor.owl.de). 10 * 11 * In function preconditions the term "valid" applied to a pointer to 12 * a structure means that the pointer is non-NULL and the structure it 13 * points to has all fields initialized to consistent values. 14 * 15 */ 16 17 #include <linux/slab.h> 18 #include "hfsplus_fs.h" 19 20 /* offsets to various blocks */ 21 #define HFS_DD_BLK 0 /* Driver Descriptor block */ 22 #define HFS_PMAP_BLK 1 /* First block of partition map */ 23 #define HFS_MDB_BLK 2 /* Block (w/i partition) of MDB */ 24 25 /* magic numbers for various disk blocks */ 26 #define HFS_DRVR_DESC_MAGIC 0x4552 /* "ER": driver descriptor map */ 27 #define HFS_OLD_PMAP_MAGIC 0x5453 /* "TS": old-type partition map */ 28 #define HFS_NEW_PMAP_MAGIC 0x504D /* "PM": new-type partition map */ 29 #define HFS_SUPER_MAGIC 0x4244 /* "BD": HFS MDB (super block) */ 30 #define HFS_MFS_SUPER_MAGIC 0xD2D7 /* MFS MDB (super block) */ 31 32 /* 33 * The new style Mac partition map 34 * 35 * For each partition on the media there is a physical block (512-byte 36 * block) containing one of these structures. These blocks are 37 * contiguous starting at block 1. 38 */ 39 struct new_pmap { 40 __be16 pmSig; /* signature */ 41 __be16 reSigPad; /* padding */ 42 __be32 pmMapBlkCnt; /* partition blocks count */ 43 __be32 pmPyPartStart; /* physical block start of partition */ 44 __be32 pmPartBlkCnt; /* physical block count of partition */ 45 u8 pmPartName[32]; /* (null terminated?) string 46 giving the name of this 47 partition */ 48 u8 pmPartType[32]; /* (null terminated?) string 49 giving the type of this 50 partition */ 51 /* a bunch more stuff we don't need */ 52 } __packed; 53 54 /* 55 * The old style Mac partition map 56 * 57 * The partition map consists for a 2-byte signature followed by an 58 * array of these structures. The map is terminated with an all-zero 59 * one of these. 60 */ 61 struct old_pmap { 62 __be16 pdSig; /* Signature bytes */ 63 struct old_pmap_entry { 64 __be32 pdStart; 65 __be32 pdSize; 66 __be32 pdFSID; 67 } pdEntry[42]; 68 } __packed; 69 70 static int hfs_parse_old_pmap(struct super_block *sb, struct old_pmap *pm, 71 sector_t *part_start, sector_t *part_size) 72 { 73 struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb); 74 int i; 75 76 for (i = 0; i < 42; i++) { 77 struct old_pmap_entry *p = &pm->pdEntry[i]; 78 79 if (p->pdStart && p->pdSize && 80 p->pdFSID == cpu_to_be32(0x54465331)/*"TFS1"*/ && 81 (sbi->part < 0 || sbi->part == i)) { 82 *part_start += be32_to_cpu(p->pdStart); 83 *part_size = be32_to_cpu(p->pdSize); 84 return 0; 85 } 86 } 87 88 return -ENOENT; 89 } 90 91 static int hfs_parse_new_pmap(struct super_block *sb, void *buf, 92 struct new_pmap *pm, sector_t *part_start, sector_t *part_size) 93 { 94 struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb); 95 int size = be32_to_cpu(pm->pmMapBlkCnt); 96 int buf_size = hfsplus_min_io_size(sb); 97 int res; 98 int i = 0; 99 100 do { 101 if (!memcmp(pm->pmPartType, "Apple_HFS", 9) && 102 (sbi->part < 0 || sbi->part == i)) { 103 *part_start += be32_to_cpu(pm->pmPyPartStart); 104 *part_size = be32_to_cpu(pm->pmPartBlkCnt); 105 return 0; 106 } 107 108 if (++i >= size) 109 return -ENOENT; 110 111 pm = (struct new_pmap *)((u8 *)pm + HFSPLUS_SECTOR_SIZE); 112 if ((u8 *)pm - (u8 *)buf >= buf_size) { 113 res = hfsplus_submit_bio(sb, 114 *part_start + HFS_PMAP_BLK + i, 115 buf, (void **)&pm, READ); 116 if (res) 117 return res; 118 } 119 } while (pm->pmSig == cpu_to_be16(HFS_NEW_PMAP_MAGIC)); 120 121 return -ENOENT; 122 } 123 124 /* 125 * Parse the partition map looking for the start and length of a 126 * HFS/HFS+ partition. 127 */ 128 int hfs_part_find(struct super_block *sb, 129 sector_t *part_start, sector_t *part_size) 130 { 131 void *buf, *data; 132 int res; 133 134 buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL); 135 if (!buf) 136 return -ENOMEM; 137 138 res = hfsplus_submit_bio(sb, *part_start + HFS_PMAP_BLK, 139 buf, &data, READ); 140 if (res) 141 goto out; 142 143 switch (be16_to_cpu(*((__be16 *)data))) { 144 case HFS_OLD_PMAP_MAGIC: 145 res = hfs_parse_old_pmap(sb, data, part_start, part_size); 146 break; 147 case HFS_NEW_PMAP_MAGIC: 148 res = hfs_parse_new_pmap(sb, buf, data, part_start, part_size); 149 break; 150 default: 151 res = -ENOENT; 152 break; 153 } 154 out: 155 kfree(buf); 156 return res; 157 } 158