123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560 |
- /* 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"
- #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) ); \
- CF_LE_W( *(unsigned short *)&__v ); \
- })
- #else
- #define GET_UNALIGNED_W(f) CF_LE_W( *(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", CF_LE_W(b->reserved),
- CF_LE_W(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", CF_LE_W(b->secs_track),
- CF_LE_W(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) : CF_LE_L(b->hidden));
- sectors = GET_UNALIGNED_W(b->sectors);
- printf("%10u sectors total\n", sectors ? sectors : CF_LE_L(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 (CF_LE_W(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 (CF_LE_W(b->reserved) >= 7 && CF_LE_W(b->info_sector) != 6)
- bbs = 6;
- else {
- bbs = CF_LE_W(b->reserved) - 1;
- if (bbs == CF_LE_W(b->info_sector))
- --bbs; /* this is never 0, as we checked reserved >= 3! */
- }
- fs->backupboot_start = bbs * lss;
- b->backup_boot = CT_LE_W(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 = CT_LE_L(0x41615252);
- i->signature = CT_LE_L(0x61417272);
- i->free_clusters = CT_LE_L(-1);
- i->next_cluster = CT_LE_L(2);
- i->boot_sign = CT_LE_W(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 < CF_LE_W(b->reserved); ++s)
- if (s != CF_LE_W(b->backup_boot))
- break;
- if (s > 0 && s < CF_LE_W(b->reserved)) {
- init_fsinfo(&i);
- fs_write((loff_t) s * lss, sizeof(i), &i);
- b->info_sector = CT_LE_W(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 = CF_LE_W(b->info_sector) * lss;
- fs_read(fs->fsinfo_start, sizeof(i), &i);
- if (i.magic != CT_LE_L(0x41615252) ||
- i.signature != CT_LE_L(0x61417272) || i.boot_sign != CT_LE_W(0xaa55)) {
- printf("FSINFO sector has bad magic number(s):\n");
- if (i.magic != CT_LE_L(0x41615252))
- printf(" Offset %llu: 0x%08x != expected 0x%08x\n",
- (unsigned long long)offsetof(struct info_sector, magic),
- CF_LE_L(i.magic), 0x41615252);
- if (i.signature != CT_LE_L(0x61417272))
- printf(" Offset %llu: 0x%08x != expected 0x%08x\n",
- (unsigned long long)offsetof(struct info_sector, signature),
- CF_LE_L(i.signature), 0x61417272);
- if (i.boot_sign != CT_LE_W(0xaa55))
- printf(" Offset %llu: 0x%04x != expected 0x%04x\n",
- (unsigned long long)offsetof(struct info_sector, boot_sign),
- CF_LE_W(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 = CF_LE_L(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 : CF_LE_L(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 = CF_LE_W(b.fat_length) ?
- CF_LE_W(b.fat_length) : CF_LE_L(b.fat32_length);
- fs->fat_start = (loff_t) CF_LE_W(b.reserved) * logical_sector_size;
- fs->root_start = ((loff_t) CF_LE_W(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 = CF_LE_L(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 = CF_LE_W(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);
- }
- static 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;
- DIR_ENT de;
- offset = find_volume_de(fs, &de);
- if (offset == 0)
- return;
- memcpy(de.name, label, 11);
- de.time = CT_LE_W((unsigned short)((mtime->tm_sec >> 1) +
- (mtime->tm_min << 5) +
- (mtime->tm_hour << 11)));
- de.date = CT_LE_W((unsigned short)(mtime->tm_mday +
- ((mtime->tm_mon + 1) << 5) +
- ((mtime->tm_year - 80) << 9)));
- 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);
- }
|