S-G Bergh | e4b9451 | 2012-11-13 14:40:37 +0100 | [diff] [blame] | 1 | /* |
| 2 | * volume_id - reads filesystem label and uuid |
| 3 | * |
| 4 | * Copyright (C) 2012 S-G Bergh <sgb@systemasis.org> |
| 5 | * |
| 6 | * This library is free software; you can redistribute it and/or |
| 7 | * modify it under the terms of the GNU Lesser General Public |
| 8 | * License as published by the Free Software Foundation; either |
| 9 | * version 2.1 of the License, or (at your option) any later version. |
| 10 | * |
| 11 | * This library is distributed in the hope that it will be useful, |
| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 14 | * Lesser General Public License for more details. |
| 15 | * |
| 16 | * You should have received a copy of the GNU Lesser General Public |
| 17 | * License along with this library; if not, write to the Free Software |
| 18 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 19 | */ |
Sven-Göran Bergh | 15d0a86 | 2013-07-31 15:57:59 +0200 | [diff] [blame] | 20 | //config:config FEATURE_VOLUMEID_EXFAT |
| 21 | //config: bool "exFAT filesystem" |
| 22 | //config: default y |
| 23 | //config: depends on VOLUMEID |
| 24 | //config: help |
Denys Vlasenko | 72089cf | 2017-07-21 09:50:55 +0200 | [diff] [blame] | 25 | //config: exFAT (extended FAT) is a proprietary file system designed especially |
| 26 | //config: for flash drives. It has many features from NTFS, but with less |
| 27 | //config: overhead. exFAT is used on most SDXC cards for consumer electronics. |
Sven-Göran Bergh | 15d0a86 | 2013-07-31 15:57:59 +0200 | [diff] [blame] | 28 | |
Denys Vlasenko | 0c4dbd4 | 2017-09-18 16:28:43 +0200 | [diff] [blame^] | 29 | //kbuild:lib-$(CONFIG_FEATURE_VOLUMEID_EXFAT) += exfat.o |
| 30 | |
S-G Bergh | e4b9451 | 2012-11-13 14:40:37 +0100 | [diff] [blame] | 31 | #include "volume_id_internal.h" |
| 32 | |
| 33 | #define EXFAT_SB_OFFSET 0 |
| 34 | #define EXFAT_DIR_ENTRY_SZ 32 |
| 35 | #define EXFAT_MAX_DIR_ENTRIES 100 |
| 36 | |
| 37 | struct exfat_super_block { |
| 38 | /* 0x00 */ uint8_t boot_jump[3]; |
| 39 | /* 0x03 */ uint8_t fs_name[8]; |
| 40 | /* 0x0B */ uint8_t must_be_zero[53]; |
| 41 | /* 0x40 */ uint64_t partition_offset; |
| 42 | /* 0x48 */ uint64_t volume_length; |
| 43 | /* 0x50 */ uint32_t fat_offset; // Sector address of 1st FAT |
| 44 | /* 0x54 */ uint32_t fat_size; // In sectors |
| 45 | /* 0x58 */ uint32_t cluster_heap_offset; // Sector address of Data Region |
| 46 | /* 0x5C */ uint32_t cluster_count; |
| 47 | /* 0x60 */ uint32_t root_dir; // Cluster address of Root Directory |
| 48 | /* 0x64 */ uint8_t vol_serial_nr[4]; // Volume ID |
| 49 | /* 0x68 */ uint16_t fs_revision; // VV.MM |
| 50 | /* 0x6A */ uint16_t vol_flags; |
| 51 | /* 0x6C */ uint8_t bytes_per_sector; // Power of 2: 9 => 512, 12 => 4096 |
| 52 | /* 0x6D */ uint8_t sectors_per_cluster; // Power of 2 |
| 53 | /* 0x6E */ uint8_t nr_of_fats; // 2 for TexFAT |
| 54 | /* 0x6F */ // ... |
| 55 | } PACKED; |
| 56 | |
| 57 | struct exfat_dir_entry { |
| 58 | /* 0x00 */ uint8_t entry_type; |
| 59 | union { |
| 60 | struct volume_label { |
| 61 | /* 0x01 */ uint8_t char_count; // Length of label |
| 62 | /* 0x02 */ uint16_t vol_label[11]; // UTF16 string without null termination |
| 63 | /* 0x18 */ uint8_t reserved[8]; |
| 64 | /* 0x20 */ } PACKED label; |
| 65 | struct volume_guid { |
| 66 | /* 0x01 */ uint8_t sec_count; |
| 67 | /* 0x02 */ uint16_t set_checksum; |
| 68 | /* 0x04 */ uint16_t flags; |
| 69 | /* 0x06 */ uint8_t vol_guid[16]; |
| 70 | /* 0x16 */ uint8_t reserved[10]; |
| 71 | /* 0x20 */ } PACKED guid; |
| 72 | } PACKED type; |
| 73 | } PACKED; |
| 74 | |
| 75 | int FAST_FUNC volume_id_probe_exfat(struct volume_id *id /*,uint64_t off*/) |
| 76 | { |
| 77 | struct exfat_super_block *sb; |
| 78 | struct exfat_dir_entry *de; |
| 79 | unsigned sector_sz; |
| 80 | unsigned cluster_sz; |
| 81 | uint64_t root_dir_off; |
| 82 | unsigned count; |
| 83 | unsigned need_lbl_guid; |
| 84 | |
| 85 | // Primary super block |
| 86 | dbg("exFAT: probing at offset 0x%x", EXFAT_SB_OFFSET); |
| 87 | sb = volume_id_get_buffer(id, EXFAT_SB_OFFSET, sizeof(*sb)); |
| 88 | |
| 89 | if (!sb) |
| 90 | return -1; |
| 91 | |
| 92 | if (memcmp(sb->fs_name, "EXFAT ", 8) != 0) |
| 93 | return -1; |
| 94 | |
| 95 | sector_sz = 1 << sb->bytes_per_sector; |
| 96 | cluster_sz = sector_sz << sb->sectors_per_cluster; |
| 97 | // There are no clusters 0 and 1, so the first cluster is 2. |
| 98 | root_dir_off = (uint64_t)EXFAT_SB_OFFSET + |
| 99 | // Hmm... should we cast sector_sz/cluster_sz to uint64_t? |
| 100 | (le32_to_cpu(sb->cluster_heap_offset)) * sector_sz + |
| 101 | (le32_to_cpu(sb->root_dir) - 2) * cluster_sz; |
| 102 | dbg("exFAT: sector size 0x%x bytes", sector_sz); |
| 103 | dbg("exFAT: cluster size 0x%x bytes", cluster_sz); |
| 104 | dbg("exFAT: root dir is at 0x%llx", (long long)root_dir_off); |
| 105 | |
| 106 | // Use DOS uuid as fallback, if no GUID set |
| 107 | volume_id_set_uuid(id, sb->vol_serial_nr, UUID_DOS); |
| 108 | |
| 109 | // EXFAT_MAX_DIR_ENTRIES is used as a safety belt. |
| 110 | // The Root Directory may hold an unlimited number of entries, |
| 111 | // so we do not want to check all. Usually label and GUID |
| 112 | // are in the beginning, but there are no guarantees. |
| 113 | need_lbl_guid = (1 << 0) | (1 << 1); |
| 114 | for (count = 0; count < EXFAT_MAX_DIR_ENTRIES; count++) { |
| 115 | de = volume_id_get_buffer(id, root_dir_off + (count * EXFAT_DIR_ENTRY_SZ), EXFAT_DIR_ENTRY_SZ); |
| 116 | if (de == NULL) |
| 117 | break; |
| 118 | if (de->entry_type == 0x00) { |
| 119 | // End of Directory Marker |
| 120 | dbg("exFAT: End of root directory reached after %u entries", count); |
| 121 | break; |
| 122 | } |
| 123 | if (de->entry_type == 0x83) { |
| 124 | // Volume Label Directory Entry |
| 125 | volume_id_set_label_unicode16(id, (uint8_t *)de->type.label.vol_label, |
| 126 | LE, 2 * de->type.label.char_count); |
| 127 | need_lbl_guid &= ~(1 << 0); |
| 128 | } |
| 129 | if (de->entry_type == 0xA0) { |
| 130 | // Volume GUID Directory Entry |
| 131 | volume_id_set_uuid(id, de->type.guid.vol_guid, UUID_DCE); |
| 132 | need_lbl_guid &= ~(1 << 1); |
| 133 | } |
| 134 | if (!need_lbl_guid) |
| 135 | break; |
| 136 | } |
| 137 | |
| 138 | IF_FEATURE_BLKID_TYPE(id->type = "exfat";) |
| 139 | return 0; |
| 140 | } |