+++ /dev/null
-/* 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) 2008-2014 Daniel Baumann <mail@daniel-baumann.ch>
- Copyright (C) 2015 Andreas Bombe <aeb@debian.org>
-
- 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/>.
-
- 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 "vfatlib.h"
-
-#define NDEBUG
-#include <debug.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 {
- uint8_t media;
- const 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 __ia64__ || defined __x86_64__ || defined __ppc64__
-/* Unaligned fields must first be copied byte-wise (little endian) */
-#define GET_UNALIGNED_W(u) \
- (((unsigned char*)(&u))[0] | (((unsigned char*)&(u))[1] << 8))
-#elif defined __s390x__
-/* Unaligned fields must first be copied byte-wise (big endian) */
-#define GET_UNALIGNED_W(pu) \
- (((unsigned char*)&(u))[1] | (((unsigned char*)&(u))[0] << 8))
-#else
-#define GET_UNALIGNED_W(f) le16toh( *(unsigned short *)&f )
-#endif
-
-static const 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",
- (unsigned long)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",
- (unsigned long)fs->data_clusters,
- (unsigned long long)fs->data_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(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 */
- uint8_t *p, *q;
- int i, pos, first = 1;
- char buf[20];
-
- printf("There are differences between boot sector and its backup.\n");
- printf("This is mostly harmless. Differences: (offset:original/backup)\n ");
- pos = 2;
- for (p = (uint8_t *) b, q = (uint8_t *) & b2, i = 0; i < sizeof(b2);
- ++p, ++q, ++i) {
- if (*p != *q) {
- sprintf(buf, "%s%u:%02x/%02x", first ? "" : ", ",
- (unsigned)(p - (uint8_t *) 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) */
- uint32_t 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((off_t)s * lss, sizeof(i), &i);
- b->info_sector = htole16(s);
- fs_write(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(" Automatically 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;
- off_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((off_t)((total_sectors & ~1) - 1) * logical_sector_size,
- logical_sector_size);
- fat_length = le16toh(b.fat_length) ?
- le16toh(b.fat_length) : le32toh(b.fat32_length);
- fs->fat_start = (off_t)le16toh(b.reserved) * logical_sector_size;
- fs->root_start = ((off_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 = (off_t)total_sectors * logical_sector_size - fs->data_start;
- fs->data_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->data_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",
- (unsigned long)fs->data_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->data_clusters >= FAT12_THRESHOLD) ? 16 : 12;
- if (fs->data_clusters >= FAT16_THRESHOLD)
- die("Too many clusters (%lu) for FAT16 filesystem.", fs->data_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->data_clusters + 2 > fat_length * logical_sector_size * 8 / 16 ||
- /* if it has one of the usual floppy sizes -> 12bit FAT */
- (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(uint8_t));
- 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->data_clusters >
- ((uint64_t)fs->fat_size * 8 / fs->fat_bits) - 2)
- die("Filesystem has %d clusters but only space for %d FAT entries.",
- fs->data_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);
-}
projects / reactos.git / blobdiff