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mkfs.c
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/******************************************************************************
* @file mkfs.c
*****************************************************************************/
#include <limits.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "common.h"
#include "lib.h"
#include "mkfs.h"
#include "msdos.h"
#include "report.h"
#include "write7x.h"
#ifndef __PDOS__
# if defined (__GNUC__)
# include <sys/time.h>
# include <unistd.h>
# else
# include <io.h>
# endif
#endif
static int align_structures = 1;
static int orphaned_sectors = 0;
static FILE *ofp;
static size_t image_size = 0;
static long total_sectors = 0;
static int heads_per_cylinder = 255;
static int sectors_per_track = 63;
static unsigned int backup_boot = 0;
static unsigned int cluster_count = 0;
static unsigned int hidden_sectors = 0;
static unsigned int info_sector = 0;
static unsigned int media_descriptor = 0xf8;
static unsigned int number_of_fats = 2;
static unsigned int reserved_sectors = 0;
static unsigned int root_cluster = 2;
static unsigned int root_entries = 512;
static unsigned int sectors_per_cluster = 4;
static unsigned int sectors_per_fat = 0;
struct mkfs_state *state = 0;
const char *program_name = 0;
static unsigned char dummy_boot_code[] =
"\x31\xC0" /* xor ax, ax */
"\xFA" /* cli */
"\x8E\xD0" /* mov ss, ax */
"\xBC\x00\x7C" /* mov sp, 0x7c00 */
"\xFB" /* sti */
"\x0E\x1F" /* push cs, pop ds */
"\xEB\x19" /* jmp XSTRING */
"\x5E" /* PRN: pop si */
"\xFC" /* cld */
"\xAC" /* XLOOP: lodsb */
"\x08\xC0" /* or al, al */
"\x74\x09" /* jz EOF */
"\xB4\x0E" /* mov ah, 0x0e */
"\xBB\x07\x00" /* mov bx, 7 */
"\xCD\x10" /* int 0x10 */
"\xEB\xF2" /* jmp short XLOOP */
"\x31\xC0" /* EOF: xor ax, ax */
"\xCD\x16" /* int 0x16 */
"\xCD\x19" /* int 0x19 */
"\xF4" /* HANG: hlt */
"\xEB\xFD" /* jmp short HANG */
"\xE8\xE4\xFF" /* XSTRINGL call PRN */
"Non-System disk or disk read error\r\n"
"Replace and strike any key when ready\r\n";
static int cdiv (int a, int b) {
return (a + b - 1) / b;
}
static int seekto (long offset) {
return fseek (ofp, (state->offset * 512) + offset, SEEK_SET);
}
static int set_fat_entry (unsigned int cluster, unsigned int value) {
unsigned char *scratch;
unsigned int i, offset, sector;
if (!(scratch = (unsigned char *) malloc (512))) {
return -1;
}
if (state->size_fat == 12) {
offset = cluster + (cluster / 2);
value &= 0x0fff;
} else if (state->size_fat == 16) {
offset = cluster * 2;
value &= 0xffff;
} else if (state->size_fat == 32) {
offset = cluster * 4;
value &= 0x0fffffff;
} else {
free (scratch);
return -1;
}
/**
* At this point, offset is the BYTE offset of the desired sector from the start
* of the FAT. Calculate the physical sector containing this FAT entry.
*/
sector = (offset / 512) + reserved_sectors;
if (seekto (sector * 512)) {
free (scratch);
report_at (program_name, 0, REPORT_ERROR, "failed whilst seeking %s", state->outfile);
return -1;
}
if (fread (scratch, 512, 1, ofp) != 1) {
free (scratch);
report_at (program_name, 0, REPORT_ERROR, "failed whilst reading %s", state->outfile);
return -1;
}
/**
* At this point, we "merely" need to extract the relevant entry. This is
* easy for FAT16 and FAT32, but a royal PITA for FAT12 as a single entry
* may span a sector boundary. The normal way around this is always to
* read two FAT sectors, but luxary is (by design intent) unavailable.
*/
offset %= 512;
if (state->size_fat == 12) {
if (offset == 511) {
if (((cluster * 3) & 0x01) == 0) {
scratch[offset] = (unsigned char) (value & 0xFF);
} else {
scratch[offset] = (unsigned char) ((scratch[offset] & 0x0F) | (value & 0xF0));
}
for (i = 0; i < number_of_fats; i++) {
long temp = sector + (i * sectors_per_fat);
if (seekto (temp * 512) || fwrite (scratch, 512, 1, ofp) != 1) {
free (scratch);
return -1;
}
}
sector++;
if (seekto (sector * 512) || fread (scratch, 512, 1, ofp) != 1) {
free (scratch);
return -1;
}
if (((cluster * 3) & 0x01) == 0) {
scratch[0] = (unsigned char) ((scratch[0] & 0xF0) | (value & 0x0F));
} else {
scratch[0] = (unsigned char) (value & 0xFF00);
}
goto _write_fat;
} else {
if (((cluster * 3) & 0x01) == 0) {
scratch[offset] = (unsigned char) (value & 0x00FF);
scratch[offset + 1] = (unsigned char) ((scratch[offset + 1] & 0x00F0) | ((value & 0x0F00) >> 8));
} else {
scratch[offset] = (unsigned char) ((scratch[offset] & 0x000F) | ((value & 0x000F) << 4));
scratch[offset + 1] = (unsigned char) ((value & 0x0FF0) >> 4);
}
goto _write_fat;
}
} else if (state->size_fat == 16) {
scratch[offset] = (value & 0xFF);
scratch[offset + 1] = (value >> 8) & 0xFF;
goto _write_fat;
} else if (state->size_fat == 32) {
scratch[offset] = (value & 0xFF);
scratch[offset + 1] = (value >> 8) & 0xFF;
scratch[offset + 2] = (value >> 16) & 0xFF;
scratch[offset + 3] = (scratch[offset + 3] & 0xF0) | ((value >> 24) & 0xFF);
goto _write_fat;
}
free (scratch);
return -1;
_write_fat:
for (i = 0; i < number_of_fats; i++) {
long temp = sector + (i * sectors_per_fat);
if (seekto (temp * 512) || fwrite (scratch, 512, 1, ofp) != 1) {
free (scratch);
return -1;
}
}
free (scratch);
return 0;
}
static unsigned int align_object (unsigned int sectors, unsigned int clustsize) {
if (align_structures) {
return (sectors + clustsize - 1) & ~(clustsize - 1);
}
return sectors;
}
static unsigned int generate_volume_id (void) {
#if defined (__PDOS__)
srand (time (NULL));
/* rand() returns int from [0,RAND_MAX], therefor only 31-bits. */
return (((unsigned int) (rand () & 0xFFFF)) << 16) | ((unsigned int) (rand() & 0xFFFF));
#elif defined (__GNUC__)
struct timeval now;
if (gettimeofday (&now, 0) != 0 || now.tv_sec == (time_t) -1 || now.tv_sec < 0) {
srand (getpid ());
/*- rand() returns int from [0,RAND_MAX], therefor only 31-bits. */
return (((unsigned int) (rand () & 0xFFFF)) << 16) | ((unsigned int) (rand() & 0xFFFF));
}
/* volume id = current time, fudged for more uniqueness. */
return ((unsigned int) now.tv_sec << 20) | (unsigned int) now.tv_usec;
#elif defined (__WATCOMC__)
srand (getpid ());
/* rand() returns int from [0,RAND_MAX], therefor only 31-bits. */
return (((unsigned int) (rand () & 0xFFFF)) << 16) | ((unsigned int) (rand() & 0xFFFF));
#endif
}
static void establish_bpb (void) {
unsigned int maxclustsize, root_dir_sectors;
unsigned int clust12, clust16, clust32;
unsigned int fatdata1216, fatdata32;
unsigned int fatlength12, fatlength16, fatlength32;
unsigned int maxclust12, maxclust16, maxclust32;
int cylinder_times_heads;
total_sectors = (image_size / 512) + orphaned_sectors;
if ((unsigned long) total_sectors > UINT_MAX) {
report_at (program_name, 0, REPORT_WARNING, "target too large, space at end will be left unused.\n");
total_sectors = UINT_MAX;
}
if (total_sectors > (long) 65535 * 16 * 63) {
heads_per_cylinder = 255;
sectors_per_track = 63;
cylinder_times_heads = total_sectors / sectors_per_track;
} else {
sectors_per_track = 17;
cylinder_times_heads = total_sectors / sectors_per_track;
heads_per_cylinder = (cylinder_times_heads + 1023) >> 10;
if (heads_per_cylinder < 4) {
heads_per_cylinder = 4;
}
if (cylinder_times_heads >= heads_per_cylinder << 10 || heads_per_cylinder > 16) {
sectors_per_track = 31;
heads_per_cylinder = 16;
cylinder_times_heads = total_sectors / sectors_per_track;
}
if (cylinder_times_heads >= heads_per_cylinder << 10) {
sectors_per_track = 63;
heads_per_cylinder = 16;
cylinder_times_heads = total_sectors / sectors_per_track;
}
}
switch (total_sectors) {
case 320: /* 160KB 5.25" */
sectors_per_cluster = 2;
root_entries = 112;
media_descriptor = 0xfe;
sectors_per_track = 8;
heads_per_cylinder = 1;
break;
case 360: /* 180KB 5.25" */
sectors_per_cluster = 2;
root_entries = 112;
media_descriptor = 0xfc;
sectors_per_track = 9;
heads_per_cylinder = 1;
break;
case 640: /* 320KB 5.25" */
sectors_per_cluster = 2;
root_entries = 112;
media_descriptor = 0xff;
sectors_per_track = 8;
heads_per_cylinder = 2;
break;
case 720: /* 360KB 5.25" */
sectors_per_cluster = 2;
root_entries = 112;
media_descriptor = 0xfd;
sectors_per_track = 9;
heads_per_cylinder = 2;
break;
case 1280: /* 640KB 5.25" / 3.5" */
sectors_per_cluster = 2;
root_entries = 112;
media_descriptor = 0xfb;
sectors_per_track = 8;
heads_per_cylinder = 2;
break;
case 1440: /* 720KB 5.25" / 3.5" */
sectors_per_cluster = 2;
root_entries = 112;
media_descriptor = 0xf9;
sectors_per_track = 9;
heads_per_cylinder = 2;
break;
case 1640: /* 820KB 3.5" */
sectors_per_cluster = 2;
root_entries = 112;
media_descriptor = 0xf9;
sectors_per_track = 10;
heads_per_cylinder = 2;
break;
case 2400: /* 1.20MB 5.25" / 3.5" */
sectors_per_cluster = 1;
root_entries = 224;
media_descriptor = 0xf9;
sectors_per_track = 15;
heads_per_cylinder = 2;
break;
case 2880: /* 1.44MB 3.5" */
sectors_per_cluster = 1;
root_entries = 224;
media_descriptor = 0xf0;
sectors_per_track = 18;
heads_per_cylinder = 2;
break;
case 3360: /* 1.68MB 3.5" */
sectors_per_cluster = 1;
root_entries = 224;
media_descriptor = 0xf0;
sectors_per_track = 21;
heads_per_cylinder = 2;
break;
case 3444: /* 1.72MB 3.5" */
sectors_per_cluster = 1;
root_entries = 224;
media_descriptor = 0xf0;
sectors_per_track = 21;
heads_per_cylinder = 2;
break;
case 5760: /* 2.88MB 3.5" */
sectors_per_cluster = 2;
root_entries = 240;
media_descriptor = 0xf0;
sectors_per_track = 36;
heads_per_cylinder = 2;
break;
}
if (!state->size_fat && image_size >= (long) 512 * 1024 * 1024) {
state->size_fat = 32;
}
if (state->size_fat == 32) {
root_entries = 0;
/*
* For FAT32, try to do the same as M$'s format command
* (see http://www.win.tue.nl/~aeb/linux/fs/fat/fatgen103.pdf p. 20):
*
* fs size <= 260M: 0.5k clusters
* fs size <= 8G: 4k clusters
* fs size <= 16G: 8k clusters
* fs size <= 32G: 16k clusters
* fs size > 32G: 32k clusters
*/
sectors_per_cluster = (total_sectors > 32 * 1024 * 1024 * 2 ? 64 :
total_sectors > 16 * 1024 * 1024 * 2 ? 32 :
total_sectors > 8 * 1024 * 1024 * 2 ? 16 :
total_sectors > 260 * 1024 * 2 ? 8 : 1);
}
if (state->sectors_per_cluster) {
sectors_per_cluster = state->sectors_per_cluster;
}
hidden_sectors = state->offset;
if (!reserved_sectors) {
reserved_sectors = (state->size_fat == 32 ? 32 : 1);
}
/*if (align_structures) {*/
/** Align number of sectors to be multiple of sectors per track, needed by DOS and mtools. */
/*total_sectors = total_sectors / sectors_per_track * sectors_per_track;*/
/*}*/
if (total_sectors <= 8192) {
if (align_structures && state->verbose) {
report_at (program_name, 0, REPORT_WARNING, "Disabling alignment due to tiny filsystem\n");
}
align_structures = 0;
}
maxclustsize = 128;
root_dir_sectors = cdiv (root_entries * 32, 512);
do {
fatdata32 = total_sectors - align_object (reserved_sectors, sectors_per_cluster);
fatdata1216 = fatdata32 - align_object (root_dir_sectors, sectors_per_cluster);
if (state->verbose) {
fprintf (stderr, "Trying with %d sectors/cluster:\n", sectors_per_cluster);
}
/**
* The factor 2 below avoids cut-off errors for number_of_fats == 1.
* The "number_of_fats * 3" is for the reserved first two FAT entries.
*/
clust12 = 2 * ((long) fatdata1216 * 512 + number_of_fats * 3) / (2 * (int) sectors_per_cluster * 512 + number_of_fats * 3);
fatlength12 = cdiv (((clust12 + 2) * 3 + 1) >> 1, 512);
fatlength12 = align_object (fatlength12, sectors_per_cluster);
/**
* Need to recalculate number of clusters, since the unused parts of the
* FATs and data area together could make up space for an additional,
* not really present cluster.
*/
clust12 = (fatdata1216 - number_of_fats * fatlength12) / sectors_per_cluster;
maxclust12 = (fatlength12 * 2 * 512) / 3;
if (maxclust12 > MAX_CLUST_12) {
maxclust12 = MAX_CLUST_12;
}
if (state->verbose && (state->size_fat == 0 || state->size_fat == 12)) {
fprintf (stderr, "Trying FAT12: #clu=%u, fatlen=%u, maxclu=%u, limit=%u\n", clust12, fatlength12, maxclust12, MAX_CLUST_12);
}
if (clust12 > maxclust12) {
clust12 = 0;
if (state->verbose && (state->size_fat == 0 || state->size_fat == 12)) {
fprintf (stderr, "Trying FAT12: too many clusters\n");
}
}
clust16 = ((long) fatdata1216 * 512 + number_of_fats * 4) / ((int) sectors_per_cluster * 512 + number_of_fats * 2);
fatlength16 = cdiv ((clust16 + 2) * 2, 512);
fatlength16 = align_object (fatlength16, sectors_per_cluster);
/**
* Need to recalculate number of clusters, since the unused parts of the
* FATs and data area together could make up space for an additional,
* not really present cluster.
*/
clust16 = (fatdata1216 - number_of_fats * fatlength16) / sectors_per_cluster;
maxclust16 = (fatlength16 * 512) / 2;
if (maxclust16 > MAX_CLUST_16) {
maxclust16 = MAX_CLUST_16;
}
if (state->verbose && (state->size_fat == 0 || state->size_fat == 16)) {
fprintf (stderr, "Trying FAT16: #clu=%u, fatlen=%u, maxclu=%u, limit=%u/%u\n", clust16, fatlength16, maxclust16, MIN_CLUST_16, MAX_CLUST_16);
}
if (clust16 > maxclust16) {
clust16 = 0;
if (state->verbose && (state->size_fat == 0 || state->size_fat == 16)) {
fprintf (stderr, "Trying FAT16: too many clusters\n");
}
}
/** This avoids that the filesystem will be misdetected as having a 12-bit FAT. */
if (clust16 && clust16 < MIN_CLUST_16) {
clust16 = 0;
if (state->verbose && (state->size_fat == 0 || state->size_fat == 16)) {
fprintf (stderr, "Trying FAT16: not enough clusters, would be misdected as FAT12\n");
}
}
clust32 = ((long) fatdata32 * 512 + number_of_fats * 8) / ((int) sectors_per_cluster * 512 + number_of_fats * 4);
fatlength32 = cdiv ((clust32 + 2) * 4, 512);
fatlength32 = align_object (fatlength32, sectors_per_cluster);
/**
* Need to recalculate number of clusters, since the unused parts of the
* FATs and data area together could make up space for an additional,
* not really present cluster.
*/
clust32 = (fatdata32 - number_of_fats * fatlength32) / sectors_per_cluster;
maxclust32 = (fatlength32 * 512) / 4;
if (maxclust32 > MAX_CLUST_32) {
maxclust32 = MAX_CLUST_32;
}
if (state->verbose && (state->size_fat == 0 || state->size_fat == 32)) {
fprintf (stderr, "Trying FAT32: #clu=%u, fatlen=%u, maxclu=%u, limit=%u/%u\n", clust32, fatlength32, maxclust32, MIN_CLUST_32, MAX_CLUST_32);
}
if (clust32 > maxclust32) {
clust32 = 0;
if (state->verbose && (state->size_fat == 0 || state->size_fat == 32)) {
fprintf (stderr, "Trying FAT32: too many clusters\n");
}
}
if (clust32 && clust32 < MIN_CLUST_32 && !(state->size_fat_by_user && state->size_fat == 32)) {
clust32 = 0;
if (state->verbose && (state->size_fat == 0 || state->size_fat == 32)) {
fprintf (stderr, "Trying FAT32: not enough clusters\n");
}
}
if ((clust12 && (state->size_fat == 0 || state->size_fat == 12)) || (clust16 && (state->size_fat == 0 || state->size_fat == 16)) || (clust32 && state->size_fat == 32)) {
break;
}
sectors_per_cluster <<= 1;
} while (sectors_per_cluster && sectors_per_cluster <= maxclustsize);
/** Use the optimal FAT size if not specified. */
if (!state->size_fat) {
state->size_fat = (clust16 > clust12 ? 16 : 12);
if (state->verbose) {
report_at (program_name, 0, REPORT_WARNING, "Choosing %d-bits for FAT\n", state->size_fat);
}
}
switch (state->size_fat) {
case 12:
cluster_count = clust12;
sectors_per_fat = fatlength12;
break;
case 16:
cluster_count = clust16;
sectors_per_fat = fatlength16;
break;
case 32:
cluster_count = clust32;
sectors_per_fat = fatlength32;
break;
default:
report_at (program_name, 0, REPORT_ERROR, "FAT not 12, 16 or 32 bits");
fclose (ofp);
remove (state->outfile);
exit (EXIT_FAILURE);
}
/** Adjust the reserved number of sectors for alignment. */
reserved_sectors = align_object (reserved_sectors, sectors_per_cluster);
/** Adjust the number of root directory entries to help enforce alignment. */
if (align_structures) {
root_entries = align_object (root_dir_sectors, sectors_per_cluster) * (512 >> 5);
}
if (state->size_fat == 32) {
if (!info_sector) {
info_sector = 1;
}
if (!backup_boot) {
if (reserved_sectors >= 7 && info_sector != 6) {
backup_boot = 6;
} else if (reserved_sectors > 3 + info_sector && info_sector != reserved_sectors - 2 && info_sector != reserved_sectors - 1) {
backup_boot = reserved_sectors - 2;
} else if (reserved_sectors >= 3 && info_sector != reserved_sectors - 1) {
backup_boot = reserved_sectors - 1;
}
}
if (backup_boot) {
if (backup_boot == info_sector) {
report_at (program_name, 0, REPORT_ERROR, "Backup boot sector must not be the same as the info sector (%d)", info_sector);
fclose (ofp);
remove (state->outfile);
exit (EXIT_FAILURE);
} else if (backup_boot >= reserved_sectors) {
report_at (program_name, 0, REPORT_ERROR, "Backup boot sector must be a reserved sector");
fclose (ofp);
remove (state->outfile);
exit (EXIT_FAILURE);
}
}
if (state->verbose) {
fprintf (stderr, "Using sector %d as backup boot sector (0 = none)\n", backup_boot);
}
}
if (!cluster_count) {
report_at (program_name, 0, REPORT_ERROR, "Not enough clusters to make a viable filesystem");
fclose (ofp);
remove (state->outfile);
exit (EXIT_FAILURE);
}
}
static void add_volume_label (void) {
struct msdos_dirent *de;
unsigned short date, time;
unsigned char *scratch;
long offset = 0;
if (!(scratch = (unsigned char *) malloc (512))) {
report_at (program_name, 0, REPORT_ERROR, "Failed to allocate memory");
fclose (ofp);
remove (state->outfile);
exit (EXIT_FAILURE);
}
if (state->size_fat == 32) {
long temp = reserved_sectors + (sectors_per_fat * 2);
offset += temp + ((root_cluster - 2) * sectors_per_cluster);
} else {
offset += reserved_sectors + (sectors_per_fat * 2);
}
if (seekto (offset * 512) || fwrite (scratch, 512, 1, ofp) != 1) {
report_at (program_name, 0, REPORT_ERROR, "Failed whilst reading root directory");
free (scratch);
fclose (ofp);
remove (state->outfile);
exit (EXIT_FAILURE);
}
de = (struct msdos_dirent *) scratch;
memset (de, 0, sizeof (*de));
date = generate_datestamp ();
time = generate_timestamp ();
memcpy (de->name, state->label, 11);
de->attr = ATTR_VOLUME_ID;
write721_to_byte_array (de->ctime, time);
write721_to_byte_array (de->cdate, date);
write721_to_byte_array (de->adate, date);
write721_to_byte_array (de->time, time);
write721_to_byte_array (de->date, date);
if (seekto (offset * 512) || fwrite (scratch, 512, 1, ofp) != 1) {
report_at (program_name, 0, REPORT_ERROR, "Failed whilst writing root directory");
free (scratch);
fclose (ofp);
remove (state->outfile);
exit (EXIT_FAILURE);
}
free (scratch);
}
static void wipe_target (void) {
unsigned int i, sectors_to_wipe = 0;
void *blank;
if (!(blank = malloc (512))) {
report_at (program_name, 0, REPORT_ERROR, "Failed to allocate memory");
fclose (ofp);
remove (state->outfile);
exit (EXIT_FAILURE);
}
memset (blank, 0, 512);
sectors_to_wipe += reserved_sectors;
sectors_to_wipe += sectors_per_fat * 2;
if (root_entries) {
sectors_to_wipe += (root_entries * 32) / 512;
} else {
sectors_to_wipe += 1;
}
seekto (0);
for (i = 0; i < sectors_to_wipe; i++) {
if (fwrite (blank, 512, 1, ofp) != 1) {
report_at (program_name, 0, REPORT_ERROR, "Failed whilst writing blank sector");
free (blank);
fclose (ofp);
remove (state->outfile);
exit (EXIT_FAILURE);
}
}
free (blank);
}
static void write_reserved (void) {
struct msdos_boot_sector bs;
struct msdos_volume_info *vi = (state->size_fat == 32 ? &bs.fstype._fat32.vi : &bs.fstype._oldfat.vi);
memset (&bs, 0, sizeof (bs));
if (state->boot) {
FILE *ifp;
if ((ifp = fopen (state->boot, "rb")) == NULL) {
report_at (program_name, 0, REPORT_ERROR, "unable to open %s", state->boot);
fclose (ofp);
remove (state->outfile);
exit (EXIT_FAILURE);
}
fseek (ifp, 0, SEEK_END);
if (ftell (ifp) != sizeof (bs)) {
report_at (program_name, 0, REPORT_ERROR, "boot sector must be %lu bytes in size", (unsigned long) sizeof (bs));
fclose (ifp);
fclose (ofp);
remove (state->outfile);
exit (EXIT_FAILURE);
}
fseek (ifp, 0, SEEK_SET);
if (fread (&bs, sizeof (bs), 1, ifp) != 1) {
report_at (program_name, 0, REPORT_ERROR, "failed to read %s", state->boot);
fclose (ifp);
fclose (ofp);
remove (state->outfile);
exit (EXIT_FAILURE);
}
fclose (ifp);
} else {
bs.boot_jump[0] = 0xEB;
bs.boot_jump[1] = ((state->size_fat == 32 ? (char *) &bs.fstype._fat32.boot_code : (char *) &bs.fstype._oldfat.boot_code) - (char *) &bs) - 2;
bs.boot_jump[2] = 0x90;
if (state->size_fat == 32) {
memcpy (bs.fstype._fat32.boot_code, dummy_boot_code, sizeof (dummy_boot_code));
} else {
memcpy (bs.fstype._oldfat.boot_code, dummy_boot_code, sizeof (dummy_boot_code));
}
bs.boot_sign[0] = 0x55;
bs.boot_sign[1] = 0xAA;
}
if (bs.boot_jump[0] != 0xEB || bs.boot_jump[1] < 0x16 || bs.boot_jump[2] != 0x90) {
goto _write_reserved;
}
memcpy (bs.system_id, "MSWIN4.1", 8);
bs.sectors_per_cluster = sectors_per_cluster;
bs.no_fats = number_of_fats;
bs.media_descriptor = media_descriptor;
write721_to_byte_array (bs.bytes_per_sector, 512);
write721_to_byte_array (bs.reserved_sectors, reserved_sectors);
write721_to_byte_array (bs.root_entries, root_entries);
write721_to_byte_array (bs.total_sectors16, total_sectors);
write721_to_byte_array (bs.sectors_per_fat16, sectors_per_fat);
if (bs.boot_jump[1] < 0x22) {
goto _write_reserved;
}
write721_to_byte_array (bs.sectors_per_track, sectors_per_track);
write721_to_byte_array (bs.heads_per_cylinder, heads_per_cylinder);
write741_to_byte_array (bs.hidden_sectors, hidden_sectors);
if (total_sectors > USHRT_MAX) {
write721_to_byte_array (bs.total_sectors16, 0);
write741_to_byte_array (bs.total_sectors32, total_sectors);
}
if (state->size_fat == 32) {
if (bs.boot_jump[1] < 0x58) {
goto _write_reserved;
}
write721_to_byte_array (bs.sectors_per_fat16, 0);
write741_to_byte_array (bs.fstype._fat32.sectors_per_fat32, sectors_per_fat);
write741_to_byte_array (bs.fstype._fat32.root_cluster, root_cluster);
write721_to_byte_array (bs.fstype._fat32.info_sector, info_sector);
write721_to_byte_array (bs.fstype._fat32.backup_boot, backup_boot);
vi->drive_no = (media_descriptor == 0xF8 ? 0x80 : 0x00);
vi->ext_boot_sign = 0x29;