diff options
author | S-G Bergh <sgb@systemasis.org> | 2012-11-13 14:40:37 +0100 |
---|---|---|
committer | Denys Vlasenko <vda.linux@googlemail.com> | 2012-11-13 14:40:37 +0100 |
commit | e4b9451413013388757cf48fbb16d8137ddd1ccb (patch) | |
tree | d72b10d4d8f8e735ad720c411967d725056f568a /util-linux/volume_id/exfat.c | |
parent | 3f21044f20ef304309651bbdef8b275475f03a28 (diff) |
volume_id: add exFAT detection
function old new delta
volume_id_probe_exfat - 294 +294
Signed-off-by: S-G Bergh <sgb@systemasis.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to 'util-linux/volume_id/exfat.c')
-rw-r--r-- | util-linux/volume_id/exfat.c | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/util-linux/volume_id/exfat.c b/util-linux/volume_id/exfat.c new file mode 100644 index 000000000..a38a8916d --- /dev/null +++ b/util-linux/volume_id/exfat.c @@ -0,0 +1,130 @@ +/* + * volume_id - reads filesystem label and uuid + * + * Copyright (C) 2012 S-G Bergh <sgb@systemasis.org> + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#include "volume_id_internal.h" + +#define EXFAT_SB_OFFSET 0 +#define EXFAT_DIR_ENTRY_SZ 32 +#define EXFAT_MAX_DIR_ENTRIES 100 + +struct exfat_super_block { +/* 0x00 */ uint8_t boot_jump[3]; +/* 0x03 */ uint8_t fs_name[8]; +/* 0x0B */ uint8_t must_be_zero[53]; +/* 0x40 */ uint64_t partition_offset; +/* 0x48 */ uint64_t volume_length; +/* 0x50 */ uint32_t fat_offset; // Sector address of 1st FAT +/* 0x54 */ uint32_t fat_size; // In sectors +/* 0x58 */ uint32_t cluster_heap_offset; // Sector address of Data Region +/* 0x5C */ uint32_t cluster_count; +/* 0x60 */ uint32_t root_dir; // Cluster address of Root Directory +/* 0x64 */ uint8_t vol_serial_nr[4]; // Volume ID +/* 0x68 */ uint16_t fs_revision; // VV.MM +/* 0x6A */ uint16_t vol_flags; +/* 0x6C */ uint8_t bytes_per_sector; // Power of 2: 9 => 512, 12 => 4096 +/* 0x6D */ uint8_t sectors_per_cluster; // Power of 2 +/* 0x6E */ uint8_t nr_of_fats; // 2 for TexFAT +/* 0x6F */ // ... +} PACKED; + +struct exfat_dir_entry { +/* 0x00 */ uint8_t entry_type; + union { + struct volume_label { +/* 0x01 */ uint8_t char_count; // Length of label +/* 0x02 */ uint16_t vol_label[11]; // UTF16 string without null termination +/* 0x18 */ uint8_t reserved[8]; +/* 0x20 */ } PACKED label; + struct volume_guid { +/* 0x01 */ uint8_t sec_count; +/* 0x02 */ uint16_t set_checksum; +/* 0x04 */ uint16_t flags; +/* 0x06 */ uint8_t vol_guid[16]; +/* 0x16 */ uint8_t reserved[10]; +/* 0x20 */ } PACKED guid; + } PACKED type; +} PACKED; + +int FAST_FUNC volume_id_probe_exfat(struct volume_id *id /*,uint64_t off*/) +{ + struct exfat_super_block *sb; + struct exfat_dir_entry *de; + unsigned sector_sz; + unsigned cluster_sz; + uint64_t root_dir_off; + unsigned count; + unsigned need_lbl_guid; + + // Primary super block + dbg("exFAT: probing at offset 0x%x", EXFAT_SB_OFFSET); + sb = volume_id_get_buffer(id, EXFAT_SB_OFFSET, sizeof(*sb)); + + if (!sb) + return -1; + + if (memcmp(sb->fs_name, "EXFAT ", 8) != 0) + return -1; + + sector_sz = 1 << sb->bytes_per_sector; + cluster_sz = sector_sz << sb->sectors_per_cluster; + // There are no clusters 0 and 1, so the first cluster is 2. + root_dir_off = (uint64_t)EXFAT_SB_OFFSET + + // Hmm... should we cast sector_sz/cluster_sz to uint64_t? + (le32_to_cpu(sb->cluster_heap_offset)) * sector_sz + + (le32_to_cpu(sb->root_dir) - 2) * cluster_sz; + dbg("exFAT: sector size 0x%x bytes", sector_sz); + dbg("exFAT: cluster size 0x%x bytes", cluster_sz); + dbg("exFAT: root dir is at 0x%llx", (long long)root_dir_off); + + // Use DOS uuid as fallback, if no GUID set + volume_id_set_uuid(id, sb->vol_serial_nr, UUID_DOS); + + // EXFAT_MAX_DIR_ENTRIES is used as a safety belt. + // The Root Directory may hold an unlimited number of entries, + // so we do not want to check all. Usually label and GUID + // are in the beginning, but there are no guarantees. + need_lbl_guid = (1 << 0) | (1 << 1); + for (count = 0; count < EXFAT_MAX_DIR_ENTRIES; count++) { + de = volume_id_get_buffer(id, root_dir_off + (count * EXFAT_DIR_ENTRY_SZ), EXFAT_DIR_ENTRY_SZ); + if (de == NULL) + break; + if (de->entry_type == 0x00) { + // End of Directory Marker + dbg("exFAT: End of root directory reached after %u entries", count); + break; + } + if (de->entry_type == 0x83) { + // Volume Label Directory Entry + volume_id_set_label_unicode16(id, (uint8_t *)de->type.label.vol_label, + LE, 2 * de->type.label.char_count); + need_lbl_guid &= ~(1 << 0); + } + if (de->entry_type == 0xA0) { + // Volume GUID Directory Entry + volume_id_set_uuid(id, de->type.guid.vol_guid, UUID_DCE); + need_lbl_guid &= ~(1 << 1); + } + if (!need_lbl_guid) + break; + } + + IF_FEATURE_BLKID_TYPE(id->type = "exfat";) + return 0; +} |