/* * volume_id - reads filesystem label and uuid * * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.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 */ //kbuild:lib-$(CONFIG_FEATURE_VOLUMEID_FAT) += fat.o //config:config FEATURE_VOLUMEID_FAT //config: bool "fat filesystem" //config: default y //config: depends on VOLUMEID #include "volume_id_internal.h" /* linux/msdos_fs.h says: */ #define FAT12_MAX 0xff4 #define FAT16_MAX 0xfff4 #define FAT32_MAX 0x0ffffff6 #define FAT_ATTR_VOLUME_ID 0x08 #define FAT_ATTR_DIR 0x10 #define FAT_ATTR_LONG_NAME 0x0f #define FAT_ATTR_MASK 0x3f #define FAT_ENTRY_FREE 0xe5 struct vfat_super_block { uint8_t boot_jump[3]; uint8_t sysid[8]; uint16_t sector_size_bytes; uint8_t sectors_per_cluster; uint16_t reserved_sct; uint8_t fats; uint16_t dir_entries; uint16_t sectors; uint8_t media; uint16_t fat_length; uint16_t secs_track; uint16_t heads; uint32_t hidden; uint32_t total_sect; union { struct fat_super_block { uint8_t unknown[3]; uint8_t serno[4]; uint8_t label[11]; uint8_t magic[8]; uint8_t dummy2[192]; uint8_t pmagic[2]; } PACKED fat; struct fat32_super_block { uint32_t fat32_length; uint16_t flags; uint8_t version[2]; uint32_t root_cluster; uint16_t insfo_sector; uint16_t backup_boot; uint16_t reserved2[6]; uint8_t unknown[3]; uint8_t serno[4]; uint8_t label[11]; uint8_t magic[8]; uint8_t dummy2[164]; uint8_t pmagic[2]; } PACKED fat32; } PACKED type; } PACKED; struct vfat_dir_entry { uint8_t name[11]; uint8_t attr; uint16_t time_creat; uint16_t date_creat; uint16_t time_acc; uint16_t date_acc; uint16_t cluster_high; uint16_t time_write; uint16_t date_write; uint16_t cluster_low; uint32_t size; } PACKED; static uint8_t *get_attr_volume_id(struct vfat_dir_entry *dir, int count) { for (;--count >= 0; dir++) { /* end marker */ if (dir->name[0] == 0x00) { dbg("end of dir"); break; } /* empty entry */ if (dir->name[0] == FAT_ENTRY_FREE) continue; /* long name */ if ((dir->attr & FAT_ATTR_MASK) == FAT_ATTR_LONG_NAME) continue; if ((dir->attr & (FAT_ATTR_VOLUME_ID | FAT_ATTR_DIR)) == FAT_ATTR_VOLUME_ID) { /* labels do not have file data */ if (dir->cluster_high != 0 || dir->cluster_low != 0) continue; dbg("found ATTR_VOLUME_ID id in root dir"); return dir->name; } dbg("skip dir entry"); } return NULL; } int FAST_FUNC volume_id_probe_vfat(struct volume_id *id /*,uint64_t fat_partition_off*/) { #define fat_partition_off ((uint64_t)0) struct vfat_super_block *vs; struct vfat_dir_entry *dir; uint16_t sector_size_bytes; uint16_t dir_entries; uint32_t sect_count; uint16_t reserved_sct; uint32_t fat_size_sct; uint32_t root_cluster; uint32_t dir_size_sct; uint32_t cluster_count; uint64_t root_start_off; uint32_t start_data_sct; uint8_t *buf; uint32_t buf_size; uint8_t *label = NULL; uint32_t next_cluster; int maxloop; dbg("probing at offset 0x%llx", (unsigned long long) fat_partition_off); vs = volume_id_get_buffer(id, fat_partition_off, 0x200); if (vs == NULL) return -1; /* believe only that's fat, don't trust the version * the cluster_count will tell us */ if (memcmp(vs->sysid, "NTFS", 4) == 0) return -1; if (memcmp(vs->type.fat32.magic, "MSWIN", 5) == 0) goto valid; if (memcmp(vs->type.fat32.magic, "FAT32 ", 8) == 0) goto valid; if (memcmp(vs->type.fat.magic, "FAT16 ", 8) == 0) goto valid; if (memcmp(vs->type.fat.magic, "MSDOS", 5) == 0) goto valid; if (memcmp(vs->type.fat.magic, "FAT12 ", 8) == 0) goto valid; /* * There are old floppies out there without a magic, so we check * for well known values and guess if it's a fat volume */ /* boot jump address check */ if ((vs->boot_jump[0] != 0xeb || vs->boot_jump[2] != 0x90) && vs->boot_jump[0] != 0xe9 ) { return -1; } /* heads check */ if (vs->heads == 0) return -1; /* cluster size check */ if (vs->sectors_per_cluster == 0 || (vs->sectors_per_cluster & (vs->sectors_per_cluster-1)) ) { return -1; } /* media check */ if (vs->media < 0xf8 && vs->media != 0xf0) return -1; /* fat count*/ if (vs->fats != 2) return -1; valid: /* sector size check */ sector_size_bytes = le16_to_cpu(vs->sector_size_bytes); if (sector_size_bytes != 0x200 && sector_size_bytes != 0x400 && sector_size_bytes != 0x800 && sector_size_bytes != 0x1000 ) { return -1; } dbg("sector_size_bytes 0x%x", sector_size_bytes); dbg("sectors_per_cluster 0x%x", vs->sectors_per_cluster); reserved_sct = le16_to_cpu(vs->reserved_sct); dbg("reserved_sct 0x%x", reserved_sct); sect_count = le16_to_cpu(vs->sectors); if (sect_count == 0) sect_count = le32_to_cpu(vs->total_sect); dbg("sect_count 0x%x", sect_count); fat_size_sct = le16_to_cpu(vs->fat_length); if (fat_size_sct == 0) fat_size_sct = le32_to_cpu(vs->type.fat32.fat32_length); fat_size_sct *= vs->fats; dbg("fat_size_sct 0x%x", fat_size_sct); dir_entries = le16_to_cpu(vs->dir_entries); dir_size_sct = ((dir_entries * sizeof(struct vfat_dir_entry)) + (sector_size_bytes-1)) / sector_size_bytes; dbg("dir_size_sct 0x%x", dir_size_sct); cluster_count = sect_count - (reserved_sct + fat_size_sct + dir_size_sct); cluster_count /= vs->sectors_per_cluster; dbg("cluster_count 0x%x", cluster_count); // if (cluster_count < FAT12_MAX) { // strcpy(id->type_version, "FAT12"); // } else if (cluster_count < FAT16_MAX) { // strcpy(id->type_version, "FAT16"); // } else { // strcpy(id->type_version, "FAT32"); // goto fat32; // } if (cluster_count >= FAT16_MAX) goto fat32; /* the label may be an attribute in the root directory */ root_start_off = (reserved_sct + fat_size_sct) * sector_size_bytes; dbg("root dir start 0x%llx", (unsigned long long) root_start_off); dbg("expected entries 0x%x", dir_entries); buf_size = dir_entries * sizeof(struct vfat_dir_entry); buf = volume_id_get_buffer(id, fat_partition_off + root_start_off, buf_size); if (buf == NULL) goto ret; label = get_attr_volume_id((struct vfat_dir_entry*) buf, dir_entries); vs = volume_id_get_buffer(id, fat_partition_off, 0x200); if (vs == NULL) return -1; if (label != NULL && memcmp(label, "NO NAME ", 11) != 0) { // volume_id_set_label_raw(id, label, 11); volume_id_set_label_string(id, label, 11); } else if (memcmp(vs->type.fat.label, "NO NAME ", 11) != 0) { // volume_id_set_label_raw(id, vs->type.fat.label, 11); volume_id_set_label_string(id, vs->type.fat.label, 11); } volume_id_set_uuid(id, vs->type.fat.serno, UUID_DOS); goto ret; fat32: /* FAT32 root dir is a cluster chain like any other directory */ buf_size = vs->sectors_per_cluster * sector_size_bytes; root_cluster = le32_to_cpu(vs->type.fat32.root_cluster); start_data_sct = reserved_sct + fat_size_sct; next_cluster = root_cluster; maxloop = 100; while (--maxloop) { uint64_t next_off_sct; uint64_t next_off; uint64_t fat_entry_off; int count; dbg("next_cluster 0x%x", (unsigned)next_cluster); next_off_sct = (uint64_t)(next_cluster - 2) * vs->sectors_per_cluster; next_off = (start_data_sct + next_off_sct) * sector_size_bytes; dbg("cluster offset 0x%llx", (unsigned long long) next_off); /* get cluster */ buf = volume_id_get_buffer(id, fat_partition_off + next_off, buf_size); if (buf == NULL) goto ret; dir = (struct vfat_dir_entry*) buf; count = buf_size / sizeof(struct vfat_dir_entry); dbg("expected entries 0x%x", count); label = get_attr_volume_id(dir, count); if (label) break; /* get FAT entry */ fat_entry_off = (reserved_sct * sector_size_bytes) + (next_cluster * sizeof(uint32_t)); dbg("fat_entry_off 0x%llx", (unsigned long long)fat_entry_off); buf = volume_id_get_buffer(id, fat_partition_off + fat_entry_off, buf_size); if (buf == NULL) goto ret; /* set next cluster */ next_cluster = le32_to_cpu(*(uint32_t*)buf) & 0x0fffffff; if (next_cluster < 2 || next_cluster > FAT32_MAX) break; } if (maxloop == 0) dbg("reached maximum follow count of root cluster chain, give up"); vs = volume_id_get_buffer(id, fat_partition_off, 0x200); if (vs == NULL) return -1; if (label != NULL && memcmp(label, "NO NAME ", 11) != 0) { // volume_id_set_label_raw(id, label, 11); volume_id_set_label_string(id, label, 11); } else if (memcmp(vs->type.fat32.label, "NO NAME ", 11) != 0) { // volume_id_set_label_raw(id, vs->type.fat32.label, 11); volume_id_set_label_string(id, vs->type.fat32.label, 11); } volume_id_set_uuid(id, vs->type.fat32.serno, UUID_DOS); ret: // volume_id_set_usage(id, VOLUME_ID_FILESYSTEM); IF_FEATURE_BLKID_TYPE(id->type = "vfat";) return 0; }