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Diffstat (limited to 'dosfstools/src/boot.c')
-rw-r--r--dosfstools/src/boot.c577
1 files changed, 577 insertions, 0 deletions
diff --git a/dosfstools/src/boot.c b/dosfstools/src/boot.c
new file mode 100644
index 0000000..b7c4e4d
--- /dev/null
+++ b/dosfstools/src/boot.c
@@ -0,0 +1,577 @@
+/* boot.c - Read and analyze ia PC/MS-DOS boot sector
+
+ Copyright (C) 1993 Werner Almesberger <werner.almesberger@lrc.di.epfl.ch>
+ Copyright (C) 1998 Roman Hodek <Roman.Hodek@informatik.uni-erlangen.de>
+ Copyright (C) 2008-2013 Daniel Baumann <mail@daniel-baumann.ch>
+
+ This program 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 3 of the License, or
+ (at your option) any later version.
+
+ This program 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.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+ On Debian systems, the complete text of the GNU General Public License
+ can be found in /usr/share/common-licenses/GPL-3 file.
+*/
+
+/* FAT32, VFAT, Atari format support, and various fixes additions May 1998
+ * by Roman Hodek <Roman.Hodek@informatik.uni-erlangen.de> */
+
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+#include <stdlib.h>
+#include <time.h>
+
+#include "common.h"
+#include "dosfsck.h"
+#include "fat.h"
+#include "io.h"
+#include "boot.h"
+#include "check.h"
+
+#define ROUND_TO_MULTIPLE(n,m) ((n) && (m) ? (n)+(m)-1-((n)-1)%(m) : 0)
+ /* don't divide by zero */
+
+/* cut-over cluster counts for FAT12 and FAT16 */
+#define FAT12_THRESHOLD 4085
+#define FAT16_THRESHOLD 65525
+
+static struct {
+ __u8 media;
+ char *descr;
+} mediabytes[] = {
+ {
+ 0xf0, "5.25\" or 3.5\" HD floppy"}, {
+ 0xf8, "hard disk"}, {
+ 0xf9, "3,5\" 720k floppy 2s/80tr/9sec or "
+ "5.25\" 1.2M floppy 2s/80tr/15sec"}, {
+ 0xfa, "5.25\" 320k floppy 1s/80tr/8sec"}, {
+ 0xfb, "3.5\" 640k floppy 2s/80tr/8sec"}, {
+ 0xfc, "5.25\" 180k floppy 1s/40tr/9sec"}, {
+ 0xfd, "5.25\" 360k floppy 2s/40tr/9sec"}, {
+ 0xfe, "5.25\" 160k floppy 1s/40tr/8sec"}, {
+0xff, "5.25\" 320k floppy 2s/40tr/8sec"},};
+
+#if defined __alpha || defined __arm || defined __arm__ || defined __ia64__ || defined __x86_64__ \
+ || defined __ppc64__ || defined __bfin__ || defined __MICROBLAZE__
+/* Unaligned fields must first be copied byte-wise */
+#define GET_UNALIGNED_W(f) \
+ ({ \
+ unsigned short __v; \
+ memcpy( &__v, &f, sizeof(__v) ); \
+ le16toh( *(unsigned short *)&__v ); \
+ })
+#else
+#define GET_UNALIGNED_W(f) le16toh( *(unsigned short *)&f )
+#endif
+
+static char *get_media_descr(unsigned char media)
+{
+ int i;
+
+ for (i = 0; i < sizeof(mediabytes) / sizeof(*mediabytes); ++i) {
+ if (mediabytes[i].media == media)
+ return (mediabytes[i].descr);
+ }
+ return ("undefined");
+}
+
+static void dump_boot(DOS_FS * fs, struct boot_sector *b, unsigned lss)
+{
+ unsigned short sectors;
+
+ printf("Boot sector contents:\n");
+ if (!atari_format) {
+ char id[9];
+ strncpy(id, (const char *)b->system_id, 8);
+ id[8] = 0;
+ printf("System ID \"%s\"\n", id);
+ } else {
+ /* On Atari, a 24 bit serial number is stored at offset 8 of the boot
+ * sector */
+ printf("Serial number 0x%x\n",
+ b->system_id[5] | (b->
+ system_id[6] << 8) | (b->system_id[7] << 16));
+ }
+ printf("Media byte 0x%02x (%s)\n", b->media, get_media_descr(b->media));
+ printf("%10d bytes per logical sector\n", GET_UNALIGNED_W(b->sector_size));
+ printf("%10d bytes per cluster\n", fs->cluster_size);
+ printf("%10d reserved sector%s\n", le16toh(b->reserved),
+ le16toh(b->reserved) == 1 ? "" : "s");
+ printf("First FAT starts at byte %llu (sector %llu)\n",
+ (unsigned long long)fs->fat_start,
+ (unsigned long long)fs->fat_start / lss);
+ printf("%10d FATs, %d bit entries\n", b->fats, fs->fat_bits);
+ printf("%10d bytes per FAT (= %u sectors)\n", fs->fat_size,
+ fs->fat_size / lss);
+ if (!fs->root_cluster) {
+ printf("Root directory starts at byte %llu (sector %llu)\n",
+ (unsigned long long)fs->root_start,
+ (unsigned long long)fs->root_start / lss);
+ printf("%10d root directory entries\n", fs->root_entries);
+ } else {
+ printf("Root directory start at cluster %lu (arbitrary size)\n",
+ fs->root_cluster);
+ }
+ printf("Data area starts at byte %llu (sector %llu)\n",
+ (unsigned long long)fs->data_start,
+ (unsigned long long)fs->data_start / lss);
+ printf("%10lu data clusters (%llu bytes)\n", fs->clusters,
+ (unsigned long long)fs->clusters * fs->cluster_size);
+ printf("%u sectors/track, %u heads\n", le16toh(b->secs_track),
+ le16toh(b->heads));
+ printf("%10u hidden sectors\n", atari_format ?
+ /* On Atari, the hidden field is only 16 bit wide and unused */
+ (((unsigned char *)&b->hidden)[0] |
+ ((unsigned char *)&b->hidden)[1] << 8) : le32toh(b->hidden));
+ sectors = GET_UNALIGNED_W(b->sectors);
+ printf("%10u sectors total\n", sectors ? sectors : le32toh(b->total_sect));
+}
+
+static void check_backup_boot(DOS_FS * fs, struct boot_sector *b, int lss)
+{
+ struct boot_sector b2;
+
+ if (!fs->backupboot_start) {
+ printf("There is no backup boot sector.\n");
+ if (le16toh(b->reserved) < 3) {
+ printf("And there is no space for creating one!\n");
+ return;
+ }
+ if (interactive)
+ printf("1) Create one\n2) Do without a backup\n");
+ else
+ printf(" Auto-creating backup boot block.\n");
+ if (!interactive || get_key("12", "?") == '1') {
+ int bbs;
+ /* The usual place for the backup boot sector is sector 6. Choose
+ * that or the last reserved sector. */
+ if (le16toh(b->reserved) >= 7 && le16toh(b->info_sector) != 6)
+ bbs = 6;
+ else {
+ bbs = le16toh(b->reserved) - 1;
+ if (bbs == le16toh(b->info_sector))
+ --bbs; /* this is never 0, as we checked reserved >= 3! */
+ }
+ fs->backupboot_start = bbs * lss;
+ b->backup_boot = htole16(bbs);
+ fs_write(fs->backupboot_start, sizeof(*b), b);
+ fs_write((loff_t) offsetof(struct boot_sector, backup_boot),
+ sizeof(b->backup_boot), &b->backup_boot);
+ printf("Created backup of boot sector in sector %d\n", bbs);
+ return;
+ } else
+ return;
+ }
+
+ fs_read(fs->backupboot_start, sizeof(b2), &b2);
+ if (memcmp(b, &b2, sizeof(b2)) != 0) {
+ /* there are any differences */
+ __u8 *p, *q;
+ int i, pos, first = 1;
+ char buf[20];
+
+ printf("There are differences between boot sector and its backup.\n");
+ printf("Differences: (offset:original/backup)\n ");
+ pos = 2;
+ for (p = (__u8 *) b, q = (__u8 *) & b2, i = 0; i < sizeof(b2);
+ ++p, ++q, ++i) {
+ if (*p != *q) {
+ sprintf(buf, "%s%u:%02x/%02x", first ? "" : ", ",
+ (unsigned)(p - (__u8 *) b), *p, *q);
+ if (pos + strlen(buf) > 78)
+ printf("\n "), pos = 2;
+ printf("%s", buf);
+ pos += strlen(buf);
+ first = 0;
+ }
+ }
+ printf("\n");
+
+ if (interactive)
+ printf("1) Copy original to backup\n"
+ "2) Copy backup to original\n" "3) No action\n");
+ else
+ printf(" Not automatically fixing this.\n");
+ switch (interactive ? get_key("123", "?") : '3') {
+ case '1':
+ fs_write(fs->backupboot_start, sizeof(*b), b);
+ break;
+ case '2':
+ fs_write(0, sizeof(b2), &b2);
+ break;
+ default:
+ break;
+ }
+ }
+}
+
+static void init_fsinfo(struct info_sector *i)
+{
+ i->magic = htole32(0x41615252);
+ i->signature = htole32(0x61417272);
+ i->free_clusters = htole32(-1);
+ i->next_cluster = htole32(2);
+ i->boot_sign = htole16(0xaa55);
+}
+
+static void read_fsinfo(DOS_FS * fs, struct boot_sector *b, int lss)
+{
+ struct info_sector i;
+
+ if (!b->info_sector) {
+ printf("No FSINFO sector\n");
+ if (interactive)
+ printf("1) Create one\n2) Do without FSINFO\n");
+ else
+ printf(" Not automatically creating it.\n");
+ if (interactive && get_key("12", "?") == '1') {
+ /* search for a free reserved sector (not boot sector and not
+ * backup boot sector) */
+ __u32 s;
+ for (s = 1; s < le16toh(b->reserved); ++s)
+ if (s != le16toh(b->backup_boot))
+ break;
+ if (s > 0 && s < le16toh(b->reserved)) {
+ init_fsinfo(&i);
+ fs_write((loff_t) s * lss, sizeof(i), &i);
+ b->info_sector = htole16(s);
+ fs_write((loff_t) offsetof(struct boot_sector, info_sector),
+ sizeof(b->info_sector), &b->info_sector);
+ if (fs->backupboot_start)
+ fs_write(fs->backupboot_start +
+ offsetof(struct boot_sector, info_sector),
+ sizeof(b->info_sector), &b->info_sector);
+ } else {
+ printf("No free reserved sector found -- "
+ "no space for FSINFO sector!\n");
+ return;
+ }
+ } else
+ return;
+ }
+
+ fs->fsinfo_start = le16toh(b->info_sector) * lss;
+ fs_read(fs->fsinfo_start, sizeof(i), &i);
+
+ if (i.magic != htole32(0x41615252) ||
+ i.signature != htole32(0x61417272) || i.boot_sign != htole16(0xaa55)) {
+ printf("FSINFO sector has bad magic number(s):\n");
+ if (i.magic != htole32(0x41615252))
+ printf(" Offset %llu: 0x%08x != expected 0x%08x\n",
+ (unsigned long long)offsetof(struct info_sector, magic),
+ le32toh(i.magic), 0x41615252);
+ if (i.signature != htole32(0x61417272))
+ printf(" Offset %llu: 0x%08x != expected 0x%08x\n",
+ (unsigned long long)offsetof(struct info_sector, signature),
+ le32toh(i.signature), 0x61417272);
+ if (i.boot_sign != htole16(0xaa55))
+ printf(" Offset %llu: 0x%04x != expected 0x%04x\n",
+ (unsigned long long)offsetof(struct info_sector, boot_sign),
+ le16toh(i.boot_sign), 0xaa55);
+ if (interactive)
+ printf("1) Correct\n2) Don't correct (FSINFO invalid then)\n");
+ else
+ printf(" Auto-correcting it.\n");
+ if (!interactive || get_key("12", "?") == '1') {
+ init_fsinfo(&i);
+ fs_write(fs->fsinfo_start, sizeof(i), &i);
+ } else
+ fs->fsinfo_start = 0;
+ }
+
+ if (fs->fsinfo_start)
+ fs->free_clusters = le32toh(i.free_clusters);
+}
+
+static char print_fat_dirty_state(void)
+{
+ printf("Dirty bit is set. Fs was not properly unmounted and"
+ " some data may be corrupt.\n");
+
+ if (interactive) {
+ printf("1) Remove dirty bit\n"
+ "2) No action\n");
+ return get_key("12", "?");
+ } else
+ printf(" Automaticaly removing dirty bit.\n");
+ return '1';
+}
+
+static void check_fat_state_bit(DOS_FS *fs, void *b)
+{
+ if (fs->fat_bits == 32) {
+ struct boot_sector *b32 = b;
+
+ if (b32->reserved3 & FAT_STATE_DIRTY) {
+ printf("0x41: ");
+ if (print_fat_dirty_state() == '1') {
+ b32->reserved3 &= ~FAT_STATE_DIRTY;
+ fs_write(0, sizeof(*b32), b32);
+ }
+ }
+ } else {
+ struct boot_sector_16 *b16 = b;
+
+ if (b16->reserved2 & FAT_STATE_DIRTY) {
+ printf("0x25: ");
+ if (print_fat_dirty_state() == '1') {
+ b16->reserved2 &= ~FAT_STATE_DIRTY;
+ fs_write(0, sizeof(*b16), b16);
+ }
+ }
+ }
+}
+
+void read_boot(DOS_FS * fs)
+{
+ struct boot_sector b;
+ unsigned total_sectors;
+ unsigned short logical_sector_size, sectors;
+ unsigned fat_length;
+ loff_t data_size;
+
+ fs_read(0, sizeof(b), &b);
+ logical_sector_size = GET_UNALIGNED_W(b.sector_size);
+ if (!logical_sector_size)
+ die("Logical sector size is zero.");
+
+ /* This was moved up because it's the first thing that will fail */
+ /* if the platform needs special handling of unaligned multibyte accesses */
+ /* but such handling isn't being provided. See GET_UNALIGNED_W() above. */
+ if (logical_sector_size & (SECTOR_SIZE - 1))
+ die("Logical sector size (%d bytes) is not a multiple of the physical "
+ "sector size.", logical_sector_size);
+
+ fs->cluster_size = b.cluster_size * logical_sector_size;
+ if (!fs->cluster_size)
+ die("Cluster size is zero.");
+ if (b.fats != 2 && b.fats != 1)
+ die("Currently, only 1 or 2 FATs are supported, not %d.\n", b.fats);
+ fs->nfats = b.fats;
+ sectors = GET_UNALIGNED_W(b.sectors);
+ total_sectors = sectors ? sectors : le32toh(b.total_sect);
+ if (verbose)
+ printf("Checking we can access the last sector of the filesystem\n");
+ /* Can't access last odd sector anyway, so round down */
+ fs_test((loff_t) ((total_sectors & ~1) - 1) * (loff_t) logical_sector_size,
+ logical_sector_size);
+ fat_length = le16toh(b.fat_length) ?
+ le16toh(b.fat_length) : le32toh(b.fat32_length);
+ fs->fat_start = (loff_t) le16toh(b.reserved) * logical_sector_size;
+ fs->root_start = ((loff_t) le16toh(b.reserved) + b.fats * fat_length) *
+ logical_sector_size;
+ fs->root_entries = GET_UNALIGNED_W(b.dir_entries);
+ fs->data_start = fs->root_start + ROUND_TO_MULTIPLE(fs->root_entries <<
+ MSDOS_DIR_BITS,
+ logical_sector_size);
+ data_size = (loff_t) total_sectors *logical_sector_size - fs->data_start;
+ fs->clusters = data_size / fs->cluster_size;
+ fs->root_cluster = 0; /* indicates standard, pre-FAT32 root dir */
+ fs->fsinfo_start = 0; /* no FSINFO structure */
+ fs->free_clusters = -1; /* unknown */
+ if (!b.fat_length && b.fat32_length) {
+ fs->fat_bits = 32;
+ fs->root_cluster = le32toh(b.root_cluster);
+ if (!fs->root_cluster && fs->root_entries)
+ /* M$ hasn't specified this, but it looks reasonable: If
+ * root_cluster is 0 but there is a separate root dir
+ * (root_entries != 0), we handle the root dir the old way. Give a
+ * warning, but convertig to a root dir in a cluster chain seems
+ * to complex for now... */
+ printf("Warning: FAT32 root dir not in cluster chain! "
+ "Compatibility mode...\n");
+ else if (!fs->root_cluster && !fs->root_entries)
+ die("No root directory!");
+ else if (fs->root_cluster && fs->root_entries)
+ printf("Warning: FAT32 root dir is in a cluster chain, but "
+ "a separate root dir\n"
+ " area is defined. Cannot fix this easily.\n");
+ if (fs->clusters < FAT16_THRESHOLD)
+ printf("Warning: Filesystem is FAT32 according to fat_length "
+ "and fat32_length fields,\n"
+ " but has only %lu clusters, less than the required "
+ "minimum of %d.\n"
+ " This may lead to problems on some systems.\n",
+ fs->clusters, FAT16_THRESHOLD);
+
+ check_fat_state_bit(fs, &b);
+ fs->backupboot_start = le16toh(b.backup_boot) * logical_sector_size;
+ check_backup_boot(fs, &b, logical_sector_size);
+
+ read_fsinfo(fs, &b, logical_sector_size);
+ } else if (!atari_format) {
+ /* On real MS-DOS, a 16 bit FAT is used whenever there would be too
+ * much clusers otherwise. */
+ fs->fat_bits = (fs->clusters >= FAT12_THRESHOLD) ? 16 : 12;
+ if (fs->clusters >= FAT16_THRESHOLD)
+ die("Too many clusters (%lu) for FAT16 filesystem.", fs->clusters);
+ check_fat_state_bit(fs, &b);
+ } else {
+ /* On Atari, things are more difficult: GEMDOS always uses 12bit FATs
+ * on floppies, and always 16 bit on harddisks. */
+ fs->fat_bits = 16; /* assume 16 bit FAT for now */
+ /* If more clusters than fat entries in 16-bit fat, we assume
+ * it's a real MSDOS FS with 12-bit fat. */
+ if (fs->clusters + 2 > fat_length * logical_sector_size * 8 / 16 ||
+ /* if it's a floppy disk --> 12bit fat */
+ device_no == 2 ||
+ /* if it's a ramdisk or loopback device and has one of the usual
+ * floppy sizes -> 12bit FAT */
+ ((device_no == 1 || device_no == 7) &&
+ (total_sectors == 720 || total_sectors == 1440 ||
+ total_sectors == 2880)))
+ fs->fat_bits = 12;
+ }
+ /* On FAT32, the high 4 bits of a FAT entry are reserved */
+ fs->eff_fat_bits = (fs->fat_bits == 32) ? 28 : fs->fat_bits;
+ fs->fat_size = fat_length * logical_sector_size;
+
+ fs->label = calloc(12, sizeof(__u8));
+ if (fs->fat_bits == 12 || fs->fat_bits == 16) {
+ struct boot_sector_16 *b16 = (struct boot_sector_16 *)&b;
+ if (b16->extended_sig == 0x29)
+ memmove(fs->label, b16->label, 11);
+ else
+ fs->label = NULL;
+ } else if (fs->fat_bits == 32) {
+ if (b.extended_sig == 0x29)
+ memmove(fs->label, &b.label, 11);
+ else
+ fs->label = NULL;
+ }
+
+ if (fs->clusters >
+ ((unsigned long long)fs->fat_size * 8 / fs->fat_bits) - 2)
+ die("File system has %d clusters but only space for %d FAT entries.",
+ fs->clusters,
+ ((unsigned long long)fs->fat_size * 8 / fs->fat_bits) - 2);
+ if (!fs->root_entries && !fs->root_cluster)
+ die("Root directory has zero size.");
+ if (fs->root_entries & (MSDOS_DPS - 1))
+ die("Root directory (%d entries) doesn't span an integral number of "
+ "sectors.", fs->root_entries);
+ if (logical_sector_size & (SECTOR_SIZE - 1))
+ die("Logical sector size (%d bytes) is not a multiple of the physical "
+ "sector size.", logical_sector_size);
+#if 0 /* linux kernel doesn't check that either */
+ /* ++roman: On Atari, these two fields are often left uninitialized */
+ if (!atari_format && (!b.secs_track || !b.heads))
+ die("Invalid disk format in boot sector.");
+#endif
+ if (verbose)
+ dump_boot(fs, &b, logical_sector_size);
+}
+
+static void write_boot_label(DOS_FS * fs, char *label)
+{
+ struct boot_sector b;
+ struct boot_sector_16 *b16 = (struct boot_sector_16 *)&b;
+
+ fs_read(0, sizeof(b), &b);
+ if (fs->fat_bits == 12 || fs->fat_bits == 16) {
+ if (b16->extended_sig != 0x29) {
+ b16->extended_sig = 0x29;
+ b16->serial = 0;
+ memmove(b16->fs_type, fs->fat_bits == 12 ? "FAT12 " : "FAT16 ",
+ 8);
+ }
+ memmove(b16->label, label, 11);
+ } else if (fs->fat_bits == 32) {
+ if (b.extended_sig != 0x29) {
+ b.extended_sig = 0x29;
+ b.serial = 0;
+ memmove(b.fs_type, "FAT32 ", 8);
+ }
+ memmove(b.label, label, 11);
+ }
+ fs_write(0, sizeof(b), &b);
+ if (fs->fat_bits == 32 && fs->backupboot_start)
+ fs_write(fs->backupboot_start, sizeof(b), &b);
+}
+
+loff_t find_volume_de(DOS_FS * fs, DIR_ENT * de)
+{
+ unsigned long cluster;
+ loff_t offset;
+ int i;
+
+ if (fs->root_cluster) {
+ for (cluster = fs->root_cluster;
+ cluster != 0 && cluster != -1;
+ cluster = next_cluster(fs, cluster)) {
+ offset = cluster_start(fs, cluster);
+ for (i = 0; i * sizeof(DIR_ENT) < fs->cluster_size; i++) {
+ fs_read(offset, sizeof(DIR_ENT), de);
+ if (de->attr & ATTR_VOLUME)
+ return offset;
+ offset += sizeof(DIR_ENT);
+ }
+ }
+ } else {
+ for (i = 0; i < fs->root_entries; i++) {
+ offset = fs->root_start + i * sizeof(DIR_ENT);
+ fs_read(offset, sizeof(DIR_ENT), de);
+ if (de->attr & ATTR_VOLUME)
+ return offset;
+ }
+ }
+
+ return 0;
+}
+
+static void write_volume_label(DOS_FS * fs, char *label)
+{
+ time_t now = time(NULL);
+ struct tm *mtime = localtime(&now);
+ loff_t offset;
+ int created;
+ DIR_ENT de;
+
+ created = 0;
+ offset = find_volume_de(fs, &de);
+ if (offset == 0)
+ {
+ created = 1;
+ offset = alloc_rootdir_entry(fs, &de, label);
+ }
+ memcpy(de.name, label, 11);
+ de.time = htole16((unsigned short)((mtime->tm_sec >> 1) +
+ (mtime->tm_min << 5) +
+ (mtime->tm_hour << 11)));
+ de.date = htole16((unsigned short)(mtime->tm_mday +
+ ((mtime->tm_mon + 1) << 5) +
+ ((mtime->tm_year - 80) << 9)));
+ if (created)
+ {
+ de.attr = ATTR_VOLUME;
+ de.ctime_ms = 0;
+ de.ctime = de.time;
+ de.cdate = de.date;
+ de.adate = de.date;
+ de.starthi = CT_LE_W(0);
+ de.start = CT_LE_W(0);
+ de.size = CT_LE_L(0);
+ }
+
+ fs_write(offset, sizeof(DIR_ENT), &de);
+}
+
+void write_label(DOS_FS * fs, char *label)
+{
+ int l = strlen(label);
+
+ while (l < 11)
+ label[l++] = ' ';
+
+ write_boot_label(fs, label);
+ write_volume_label(fs, label);
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-28 11:28:20 +0000