--- /dev/null
+/*
+ * Copyright (C) 1999 by Andries Brouwer
+ * Copyright (C) 1999, 2000, 2003 by Theodore Ts'o
+ * Copyright (C) 2001 by Andreas Dilger
+ * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
+ * Copyright (C) 2008 Karel Zak <kzak@redhat.com>
+ *
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This file 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 General Public License for more details.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <ctype.h>
+#include <stdint.h>
+
+#include "blkidP.h"
+
+/* Yucky misaligned values */
+struct vfat_super_block {
+/* 00*/ unsigned char vs_ignored[3];
+/* 03*/ unsigned char vs_sysid[8];
+/* 0b*/ unsigned char vs_sector_size[2];
+/* 0d*/ uint8_t vs_cluster_size;
+/* 0e*/ uint16_t vs_reserved;
+/* 10*/ uint8_t vs_fats;
+/* 11*/ unsigned char vs_dir_entries[2];
+/* 13*/ unsigned char vs_sectors[2];
+/* 15*/ unsigned char vs_media;
+/* 16*/ uint16_t vs_fat_length;
+/* 18*/ uint16_t vs_secs_track;
+/* 1a*/ uint16_t vs_heads;
+/* 1c*/ uint32_t vs_hidden;
+/* 20*/ uint32_t vs_total_sect;
+/* 24*/ uint32_t vs_fat32_length;
+/* 28*/ uint16_t vs_flags;
+/* 2a*/ uint8_t vs_version[2];
+/* 2c*/ uint32_t vs_root_cluster;
+/* 30*/ uint16_t vs_insfo_sector;
+/* 32*/ uint16_t vs_backup_boot;
+/* 34*/ uint16_t vs_reserved2[6];
+/* 40*/ unsigned char vs_unknown[3];
+/* 43*/ unsigned char vs_serno[4];
+/* 47*/ unsigned char vs_label[11];
+/* 52*/ unsigned char vs_magic[8];
+/* 5a*/ unsigned char vs_dummy2[164];
+/*1fe*/ unsigned char vs_pmagic[2];
+};
+
+/* Yucky misaligned values */
+struct msdos_super_block {
+/* 00*/ unsigned char ms_ignored[3];
+/* 03*/ unsigned char ms_sysid[8];
+/* 0b*/ unsigned char ms_sector_size[2];
+/* 0d*/ uint8_t ms_cluster_size;
+/* 0e*/ uint16_t ms_reserved;
+/* 10*/ uint8_t ms_fats;
+/* 11*/ unsigned char ms_dir_entries[2];
+/* 13*/ unsigned char ms_sectors[2];
+/* 15*/ unsigned char ms_media;
+/* 16*/ uint16_t ms_fat_length;
+/* 18*/ uint16_t ms_secs_track;
+/* 1a*/ uint16_t ms_heads;
+/* 1c*/ uint32_t ms_hidden;
+/* 20*/ uint32_t ms_total_sect;
+/* 24*/ unsigned char ms_unknown[3];
+/* 27*/ unsigned char ms_serno[4];
+/* 2b*/ unsigned char ms_label[11];
+/* 36*/ unsigned char ms_magic[8];
+/* 3d*/ unsigned char ms_dummy2[192];
+/*1fe*/ unsigned char ms_pmagic[2];
+};
+
+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;
+};
+
+/* maximum number of clusters */
+#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
+
+static const char *no_name = "NO NAME ";
+
+static unsigned char *search_fat_label(struct vfat_dir_entry *dir, int count)
+{
+ int i;
+
+ for (i = 0; i < count; i++) {
+ if (dir[i].name[0] == 0x00)
+ break;
+
+ if ((dir[i].name[0] == FAT_ENTRY_FREE) ||
+ (dir[i].cluster_high != 0 || dir[i].cluster_low != 0) ||
+ ((dir[i].attr & FAT_ATTR_MASK) == FAT_ATTR_LONG_NAME))
+ continue;
+
+ if ((dir[i].attr & (FAT_ATTR_VOLUME_ID | FAT_ATTR_DIR)) ==
+ FAT_ATTR_VOLUME_ID) {
+ return dir[i].name;
+ }
+ }
+ return 0;
+}
+
+/*
+ * The FAT filesystem could be without a magic string in superblock
+ * (e.g. old floppies). This heuristic for FAT detection is inspired
+ * by http://vrfy.org/projects/volume_id/ and Linux kernel.
+ * [7-Jul-2005, Karel Zak <kzak@redhat.com>]
+ */
+static int probe_fat_nomagic(blkid_probe pr, const struct blkid_idmag *mag)
+{
+ struct msdos_super_block *ms;
+
+ ms = blkid_probe_get_sb(pr, mag, struct msdos_super_block);
+ if (!ms)
+ return -1;
+
+ /* heads check */
+ if (ms->ms_heads == 0)
+ return 1;
+
+ /* cluster size check*/
+ if (ms->ms_cluster_size == 0 ||
+ (ms->ms_cluster_size & (ms->ms_cluster_size-1)))
+ return 1;
+
+ /* media check */
+ if (ms->ms_media < 0xf8 && ms->ms_media != 0xf0)
+ return 1;
+
+ /* fat counts(Linux kernel expects at least 1 FAT table) */
+ if (!ms->ms_fats)
+ return 1;
+
+ /*
+ * OS/2 and apparently DFSee will place a FAT12/16-like
+ * pseudo-superblock in the first 512 bytes of non-FAT
+ * filesystems --- at least JFS and HPFS, and possibly others.
+ * So we explicitly check for those filesystems at the
+ * FAT12/16 filesystem magic field identifier, and if they are
+ * present, we rule this out as a FAT filesystem, despite the
+ * FAT-like pseudo-header.
+ */
+ if ((memcmp(ms->ms_magic, "JFS ", 8) == 0) ||
+ (memcmp(ms->ms_magic, "HPFS ", 8) == 0))
+ return 1;
+
+ return 0;
+}
+
+/* FAT label extraction from the root directory taken from Kay
+ * Sievers's volume_id library */
+static int probe_vfat(blkid_probe pr, const struct blkid_idmag *mag)
+{
+ struct vfat_super_block *vs;
+ struct msdos_super_block *ms;
+ struct vfat_dir_entry *dir;
+ const unsigned char *vol_label = 0, *tmp;
+ unsigned char *vol_serno;
+ int maxloop = 100;
+ uint16_t sector_size, dir_entries, reserved;
+ uint32_t sect_count, fat_size, dir_size, cluster_count, fat_length;
+ uint32_t buf_size, start_data_sect, next, root_start, root_dir_entries;
+
+
+ /* non-standard magic strings */
+ if (mag->len <= 2 && probe_fat_nomagic(pr, mag) != 0)
+ return 1;
+
+ vs = blkid_probe_get_sb(pr, mag, struct vfat_super_block);
+ if (!vs)
+ return -1;
+
+ ms = blkid_probe_get_sb(pr, mag, struct msdos_super_block);
+ if (!ms)
+ return -1;
+
+ /* sector size check */
+ tmp = (unsigned char *) &ms->ms_sector_size;
+ sector_size = tmp[0] + (tmp[1] << 8);
+ if (sector_size != 0x200 && sector_size != 0x400 &&
+ sector_size != 0x800 && sector_size != 0x1000)
+ return 1;
+
+ tmp = (unsigned char *) &ms->ms_dir_entries;
+ dir_entries = tmp[0] + (tmp[1] << 8);
+ reserved = le16_to_cpu(ms->ms_reserved);
+ tmp = (unsigned char *) &ms->ms_sectors;
+ sect_count = tmp[0] + (tmp[1] << 8);
+ if (sect_count == 0)
+ sect_count = le32_to_cpu(ms->ms_total_sect);
+
+ fat_length = le16_to_cpu(ms->ms_fat_length);
+ if (fat_length == 0)
+ fat_length = le32_to_cpu(vs->vs_fat32_length);
+
+ fat_size = fat_length * ms->ms_fats;
+ dir_size = ((dir_entries * sizeof(struct vfat_dir_entry)) +
+ (sector_size-1)) / sector_size;
+
+ cluster_count = sect_count - (reserved + fat_size + dir_size);
+ if (ms->ms_cluster_size == 0)
+ return 1;
+ cluster_count /= ms->ms_cluster_size;
+
+ if (cluster_count > FAT32_MAX)
+ return 1;
+
+ if (ms->ms_fat_length) {
+ /* the label may be an attribute in the root directory */
+ root_start = (reserved + fat_size) * sector_size;
+ root_dir_entries = vs->vs_dir_entries[0] +
+ (vs->vs_dir_entries[1] << 8);
+
+ buf_size = root_dir_entries * sizeof(struct vfat_dir_entry);
+ dir = (struct vfat_dir_entry *)
+ blkid_probe_get_buffer(pr, root_start, buf_size);
+ if (dir)
+ vol_label = search_fat_label(dir, root_dir_entries);
+
+ if (!vol_label || !memcmp(vol_label, no_name, 11))
+ vol_label = ms->ms_label;
+ vol_serno = ms->ms_serno;
+
+ blkid_probe_set_value(pr, "SEC_TYPE", (unsigned char *) "msdos",
+ sizeof("msdos"));
+ } else {
+ unsigned char *buf;
+ /* Search the FAT32 root dir for the label attribute */
+ buf_size = vs->vs_cluster_size * sector_size;
+ start_data_sect = reserved + fat_size;
+
+ next = le32_to_cpu(vs->vs_root_cluster);
+ while (next && --maxloop) {
+ uint32_t next_sect_off;
+ __u64 next_off, fat_entry_off;
+ int count;
+
+ next_sect_off = (next - 2) * vs->vs_cluster_size;
+ next_off = (start_data_sect + next_sect_off) *
+ sector_size;
+
+ dir = (struct vfat_dir_entry *)
+ blkid_probe_get_buffer(pr, next_off, buf_size);
+ if (dir == NULL)
+ break;
+
+ count = buf_size / sizeof(struct vfat_dir_entry);
+
+ vol_label = search_fat_label(dir, count);
+ if (vol_label)
+ break;
+
+ /* get FAT entry */
+ fat_entry_off = (reserved * sector_size) +
+ (next * sizeof(uint32_t));
+ buf = blkid_probe_get_buffer(pr, fat_entry_off, buf_size);
+ if (buf == NULL)
+ break;
+
+ /* set next cluster */
+ next = le32_to_cpu(*((uint32_t *) buf) & 0x0fffffff);
+ }
+
+ if (!vol_label || !memcmp(vol_label, no_name, 11))
+ vol_label = vs->vs_label;
+ vol_serno = vs->vs_serno;
+ }
+
+ if (vol_label && memcmp(vol_label, no_name, 11))
+ blkid_probe_set_label(pr, (unsigned char *) vol_label, 11);
+
+ /* We can't just print them as %04X, because they are unaligned */
+ blkid_probe_sprintf_uuid(pr, vol_serno, 4, "%02X%02X-%02X%02X",
+ vol_serno[3], vol_serno[2], vol_serno[1], vol_serno[0]);
+
+ return 0;
+}
+
+
+const struct blkid_idinfo _idinfo =
+{
+ .name = "vfat",
+ .usage = BLKID_USAGE_FILESYSTEM,
+ .probefunc = probe_vfat,
+ .magics =
+ {
+ { .magic = "MSWIN", .len = 5, .sboff = 0x52 },
+ { .magic = "FAT32 ", .len = 8, .sboff = 0x52 },
+ { .magic = "MSDOS", .len = 5, .sboff = 0x36 },
+ { .magic = "FAT16 ", .len = 8, .sboff = 0x36 },
+ { .magic = "FAT12 ", .len = 8, .sboff = 0x36 },
+ { .magic = "\353", .len = 1, },
+ { .magic = "\351", .len = 1, },
+ { .magic = "\125\252", .len = 2, .sboff = 0x1fe },
+ { NULL }
+ }
+};
+
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