1 files changed, 518 insertions, 0 deletions

diff --git a/dosfstools/src/boot.c b/dosfstools/src/boot.c
new file mode 100644
index 000000000..bbaee0471
--- /dev/null
+++ b/dosfstools/src/boot.c
@@ -0,0 +1,518 @@
+/* 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>
+
+   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);
+}
+
+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);
+
+	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);
+    } 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);
+}