util-linux/mkfs_vfat.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * mkfs_vfat: utility to create FAT32 filesystem
   4  * inspired by dosfstools
   5  *
   6  * Busybox'ed (2009) by Vladimir Dronnikov <dronnikov@gmail.com>
   7  *
   8  * Licensed under GPLv2, see file LICENSE in this tarball for details.
   9  */
  10 #include "libbb.h"
  11
  12 #include <linux/hdreg.h> /* HDIO_GETGEO */
  13 #include <linux/fd.h>    /* FDGETPRM */
  14 #include <sys/mount.h>   /* BLKSSZGET */
  15 #if !defined(BLKSSZGET)
  16 # define BLKSSZGET _IO(0x12, 104)
  17 #endif
  18 //#include <linux/msdos_fs.h>
  19 #include "volume_id/volume_id_internal.h"
  20
  21 #define SECTOR_SIZE             512
  22
  23 #define SECTORS_PER_BLOCK       (BLOCK_SIZE / SECTOR_SIZE)
  24
  25 // M$ says the high 4 bits of a FAT32 FAT entry are reserved
  26 #define EOF_FAT32       0x0FFFFFF8
  27 #define BAD_FAT32       0x0FFFFFF7
  28 #define MAX_CLUST_32    0x0FFFFFF0
  29
  30 #define ATTR_VOLUME     8
  31
  32 #define NUM_FATS        2
  33
  34 /* FAT32 filesystem looks like this:
  35  * sector -nn...-1: "hidden" sectors, all sectors before this partition
  36  * (-h hidden-sectors sets it. Useful only for boot loaders,
  37  *  they need to know _disk_ offset in order to be able to correctly
  38  *  address sectors relative to start of disk)
  39  * sector 0: boot sector
  40  * sector 1: info sector
  41  * sector 2: set aside for boot code which didn't fit into sector 0
  42  * ...(zero-filled sectors)...
  43  * sector B: backup copy of sector 0 [B set by -b backup-boot-sector]
  44  * sector B+1: backup copy of sector 1
  45  * sector B+2: backup copy of sector 2
  46  * ...(zero-filled sectors)...
  47  * sector R: FAT#1 [R set by -R reserved-sectors]
  48  * ...(FAT#1)...
  49  * sector R+fat_size: FAT#2
  50  * ...(FAT#2)...
  51  * sector R+fat_size*2: cluster #2
  52  * ...(cluster #2)...
  53  * sector R+fat_size*2+clust_size: cluster #3
  54  * ...(the rest is filled by clusters till the end)...
  55  */
  56
  57 enum {
  58 // Perhaps this should remain constant
  59         info_sector_number = 1,
  60 // TODO: make these cmdline options
  61 // dont forget sanity check: backup_boot_sector + 3 <= reserved_sect
  62         backup_boot_sector = 3,
  63         reserved_sect      = 6,
  64 };
  65
  66 // how many blocks we try to read while testing
  67 #define TEST_BUFFER_BLOCKS      16
  68
  69 struct msdos_dir_entry {
  70         char     name[11];       /* 000 name and extension */
  71         uint8_t  attr;           /* 00b attribute bits */
  72         uint8_t  lcase;          /* 00c case for base and extension */
  73         uint8_t  ctime_cs;       /* 00d creation time, centiseconds (0-199) */
  74         uint16_t ctime;          /* 00e creation time */
  75         uint16_t cdate;          /* 010 creation date */
  76         uint16_t adate;          /* 012 last access date */
  77         uint16_t starthi;        /* 014 high 16 bits of cluster in FAT32 */
  78         uint16_t time;           /* 016 time */
  79         uint16_t date;           /* 018 date */
  80         uint16_t start;          /* 01a first cluster */
  81         uint32_t size;           /* 01c file size in bytes */
  82 } PACKED;
  83
  84 /* Example of boot sector's beginning:
  85 0000  eb 58 90 4d 53 57 49 4e  34 2e 31 00 02 08 26 00  |...MSWIN4.1...&.|
  86 0010  02 00 00 00 00 f8 00 00  3f 00 ff 00 3f 00 00 00  |........?...?...|
  87 0020  54 9b d0 00 0d 34 00 00  00 00 00 00 02 00 00 00  |T....4..........|
  88 0030  01 00 06 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
  89 0040  80 00 29 71 df 51 e0 4e  4f 20 4e 41 4d 45 20 20  |..)q.Q.NO NAME  |
  90 0050  20 20 46 41 54 33 32 20  20 20 33 c9 8e d1 bc f4  |  FAT32   3.....|
  91 */
  92 struct msdos_volume_info { /* (offsets are relative to start of boot sector) */
  93         uint8_t  drive_number;    /* 040 BIOS drive number */
  94         uint8_t  reserved;        /* 041 unused */
  95         uint8_t  ext_boot_sign;   /* 042 0x29 if fields below exist (DOS 3.3+) */
  96         uint32_t volume_id32;     /* 043 volume ID number */
  97         char     volume_label[11];/* 047 volume label */
  98         char     fs_type[8];      /* 052 typically "FATnn" */
  99 } PACKED;                         /* 05a end. Total size 26 (0x1a) bytes */
 100
 101 struct msdos_boot_sector {
 102         char     boot_jump[3];       /* 000 short or near jump instruction */
 103         char     system_id[8];       /* 003 name - can be used to special case partition manager volumes */
 104         uint16_t bytes_per_sect;     /* 00b bytes per logical sector */
 105         uint8_t  sect_per_clust;     /* 00d sectors/cluster */
 106         uint16_t reserved_sect;      /* 00e reserved sectors (sector offset of 1st FAT relative to volume start) */
 107         uint8_t  fats;               /* 010 number of FATs */
 108         uint16_t dir_entries;        /* 011 root directory entries */
 109         uint16_t volume_size_sect;   /* 013 volume size in sectors */
 110         uint8_t  media_byte;         /* 015 media code */
 111         uint16_t sect_per_fat;       /* 016 sectors/FAT */
 112         uint16_t sect_per_track;     /* 018 sectors per track */
 113         uint16_t heads;              /* 01a number of heads */
 114         uint32_t hidden;             /* 01c hidden sectors (sector offset of volume within physical disk) */
 115         uint32_t fat32_volume_size_sect; /* 020 volume size in sectors (if volume_size_sect == 0) */
 116         uint32_t fat32_sect_per_fat; /* 024 sectors/FAT */
 117         uint16_t fat32_flags;        /* 028 bit 8: fat mirroring, low 4: active fat */
 118         uint8_t  fat32_version[2];   /* 02a major, minor filesystem version (I see 0,0) */
 119         uint32_t fat32_root_cluster; /* 02c first cluster in root directory */
 120         uint16_t fat32_info_sector;  /* 030 filesystem info sector (usually 1) */
 121         uint16_t fat32_backup_boot;  /* 032 backup boot sector (usually 6) */
 122         uint32_t reserved2[3];       /* 034 unused */
 123         struct msdos_volume_info vi; /* 040 */
 124         char     boot_code[0x200 - 0x5a - 2]; /* 05a */
 125 #define BOOT_SIGN 0xAA55
 126         uint16_t boot_sign;          /* 1fe */
 127 } PACKED;
 128
 129 #define FAT_FSINFO_SIG1 0x41615252
 130 #define FAT_FSINFO_SIG2 0x61417272
 131 struct fat32_fsinfo {
 132         uint32_t signature1;         /* 0x52,0x52,0x41,0x61, "RRaA" */
 133         uint32_t reserved1[128 - 8];
 134         uint32_t signature2;         /* 0x72,0x72,0x61,0x41, "rrAa" */
 135         uint32_t free_clusters;      /* free cluster count.  -1 if unknown */
 136         uint32_t next_cluster;       /* most recently allocated cluster */
 137         uint32_t reserved2[3];
 138         uint16_t reserved3;          /* 1fc */
 139         uint16_t boot_sign;          /* 1fe */
 140 } PACKED;
 141
 142 struct bug_check {
 143         char BUG1[sizeof(struct msdos_dir_entry  ) == 0x20 ? 1 : -1];
 144         char BUG2[sizeof(struct msdos_volume_info) == 0x1a ? 1 : -1];
 145         char BUG3[sizeof(struct msdos_boot_sector) == 0x200 ? 1 : -1];
 146         char BUG4[sizeof(struct fat32_fsinfo     ) == 0x200 ? 1 : -1];
 147 };
 148
 149 static const char boot_code[] ALIGN1 =
 150         "\x0e"          /* 05a:         push  cs */
 151         "\x1f"          /* 05b:         pop   ds */
 152         "\xbe\x77\x7c"  /*  write_msg:  mov   si, offset message_txt */
 153         "\xac"          /* 05f:         lodsb */
 154         "\x22\xc0"      /* 060:         and   al, al */
 155         "\x74\x0b"      /* 062:         jz    key_press */
 156         "\x56"          /* 064:         push  si */
 157         "\xb4\x0e"      /* 065:         mov   ah, 0eh */
 158         "\xbb\x07\x00"  /* 067:         mov   bx, 0007h */
 159         "\xcd\x10"      /* 06a:         int   10h */
 160         "\x5e"          /* 06c:         pop   si */
 161         "\xeb\xf0"      /* 06d:         jmp   write_msg */
 162         "\x32\xe4"      /*  key_press:  xor   ah, ah */
 163         "\xcd\x16"      /* 071:         int   16h */
 164         "\xcd\x19"      /* 073:         int   19h */
 165         "\xeb\xfe"      /*  foo:        jmp   foo */
 166         /* 077: message_txt: */
 167         "This is not a bootable disk\r\n";
 168
 169
 170 #define MARK_CLUSTER(cluster, value) \
 171         ((uint32_t *)fat)[cluster] = cpu_to_le32(value)
 172
 173 void BUG_unsupported_field_size(void);
 174 #define STORE_LE(field, value) \
 175 do { \
 176         if (sizeof(field) == 4) \
 177                 field = cpu_to_le32(value); \
 178         else if (sizeof(field) == 2) \
 179                 field = cpu_to_le16(value); \
 180         else if (sizeof(field) == 1) \
 181                 field = (value); \
 182         else \
 183                 BUG_unsupported_field_size(); \
 184 } while (0)
 185
 186 /* compat:
 187  * mkdosfs 2.11 (12 Mar 2005)
 188  * Usage: mkdosfs [-A] [-c] [-C] [-v] [-I] [-l bad-block-file]
 189  *        [-b backup-boot-sector]
 190  *        [-m boot-msg-file] [-n volume-name] [-i volume-id]
 191  *        [-s sectors-per-cluster] [-S logical-sector-size]
 192  *        [-f number-of-FATs]
 193  *        [-h hidden-sectors] [-F fat-size] [-r root-dir-entries]
 194  *        [-R reserved-sectors]
 195  *        /dev/name [blocks]
 196  */
 197 int mkfs_vfat_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 198 int mkfs_vfat_main(int argc UNUSED_PARAM, char **argv)
 199 {
 200         struct stat st;
 201         const char *volume_label = "";
 202         char *buf;
 203         char *device_name;
 204         uoff_t volume_size_bytes;
 205         uoff_t volume_size_sect;
 206         uint32_t total_clust;
 207         uint32_t volume_id;
 208         int dev;
 209         unsigned bytes_per_sect;
 210         unsigned sect_per_fat;
 211         unsigned opts;
 212         uint16_t sect_per_track;
 213         uint8_t media_byte;
 214         uint8_t sect_per_clust;
 215         uint8_t heads;
 216         enum {
 217                 OPT_A = 1 << 0,  // [IGNORED] atari format
 218                 OPT_b = 1 << 1,  // [IGNORED] location of backup boot sector
 219                 OPT_c = 1 << 2,  // [IGNORED] check filesystem
 220                 OPT_C = 1 << 3,  // [IGNORED] create a new file
 221                 OPT_f = 1 << 4,  // [IGNORED] number of FATs
 222                 OPT_F = 1 << 5,  // [IGNORED, implied 32] choose FAT size
 223                 OPT_h = 1 << 6,  // [IGNORED] number of hidden sectors
 224                 OPT_I = 1 << 7,  // [IGNORED] don't bark at entire disk devices
 225                 OPT_i = 1 << 8,  // [IGNORED] volume ID
 226                 OPT_l = 1 << 9,  // [IGNORED] bad block filename
 227                 OPT_m = 1 << 10, // [IGNORED] message file
 228                 OPT_n = 1 << 11, // volume label
 229                 OPT_r = 1 << 12, // [IGNORED] root directory entries
 230                 OPT_R = 1 << 13, // [IGNORED] number of reserved sectors
 231                 OPT_s = 1 << 14, // [IGNORED] sectors per cluster
 232                 OPT_S = 1 << 15, // [IGNORED] sector size
 233                 OPT_v = 1 << 16, // verbose
 234         };
 235
 236         opt_complementary = "-1";//:b+:f+:F+:h+:r+:R+:s+:S+:vv:c--l:l--c";
 237         opts = getopt32(argv, "Ab:cCf:F:h:Ii:l:m:n:r:R:s:S:v",
 238                 NULL, NULL, NULL, NULL, NULL,
 239                 NULL, NULL, &volume_label, NULL, NULL, NULL, NULL);
 240         argv += optind;
 241
 242         // cache device name
 243         device_name = argv[0];
 244         // default volume ID = creation time
 245         volume_id = time(NULL);
 246
 247         dev = xopen(device_name, O_EXCL | O_RDWR);
 248         if (fstat(dev, &st) < 0)
 249                 bb_simple_perror_msg_and_die(device_name);
 250
 251         //
 252         // Get image size and sector size
 253         //
 254         bytes_per_sect = SECTOR_SIZE;
 255         volume_size_bytes = st.st_size;
 256         if (!S_ISBLK(st.st_mode)) {
 257                 if (!S_ISREG(st.st_mode)) {
 258                         if (!argv[1])
 259                                 bb_error_msg_and_die("image size must be specified");
 260                 }
 261                 // not a block device, skip bad sectors check
 262                 opts &= ~OPT_c;
 263         } else {
 264                 int min_bytes_per_sect;
 265
 266                 // more portable than BLKGETSIZE[64]
 267                 volume_size_bytes = xlseek(dev, 0, SEEK_END);
 268                 xlseek(dev, 0, SEEK_SET);
 269 #if 0
 270                 unsigned device_num;
 271                 // for true block devices we do check sanity
 272                 device_num = st.st_rdev & 0xff3f;
 273                 // do we allow to format the whole disk device?
 274                 if (!(opts & OPT_I) && (
 275                         device_num == 0x0300 || // hda, hdb
 276                         (device_num & 0xff0f) == 0x0800 || // sd
 277                         device_num == 0x0d00 || // xd
 278                         device_num == 0x1600 )  // hdc, hdd
 279                 )
 280                         bb_error_msg_and_die("will not try to make filesystem on full-disk device (use -I if wanted)");
 281                 // can't work on mounted filesystems
 282                 if (find_mount_point(device_name, 0))
 283                         bb_error_msg_and_die("can't format mounted filesystem");
 284 #endif
 285                 // get true sector size
 286                 // (parameter must be int*, not long* or size_t*)
 287                 xioctl(dev, BLKSSZGET, &min_bytes_per_sect);
 288                 if (min_bytes_per_sect > SECTOR_SIZE) {
 289                         bytes_per_sect = min_bytes_per_sect;
 290                         bb_error_msg("for this device sector size is %u", min_bytes_per_sect);
 291                 }
 292         }
 293         if (argv[1]) {
 294                 volume_size_bytes = XATOOFF(argv[1]);
 295                 if (volume_size_bytes >= MAXINT(off_t) / 1024)
 296                         bb_error_msg_and_die("image size is too big");
 297                 volume_size_bytes *= 1024;
 298         }
 299         volume_size_sect = volume_size_bytes / bytes_per_sect;
 300
 301         //
 302         // Find out or guess media parameters
 303         //
 304         media_byte = 0xf8;
 305         heads = 255;
 306         sect_per_track = 63;
 307         sect_per_clust = 1;
 308         {
 309                 struct hd_geometry geometry;
 310                 // size (in sectors), sect (per track), head
 311                 struct floppy_struct param;
 312
 313                 // N.B. whether to use HDIO_GETGEO or HDIO_REQ?
 314                 if (ioctl(dev, HDIO_GETGEO, &geometry) == 0
 315                  && geometry.sectors
 316                  && geometry.heads
 317                 ) {
 318                         // hard drive
 319                         sect_per_track = geometry.sectors;
 320                         heads = geometry.heads;
 321
 322  set_cluster_size:
 323                         /* For FAT32, try to do the same as M$'s format command
 324                          * (see http://www.win.tue.nl/~aeb/linux/fs/fat/fatgen103.pdf p. 20):
 325                          * fs size <= 260M: 0.5k clusters
 326                          * fs size <=   8G: 4k clusters
 327                          * fs size <=  16G: 8k clusters
 328                          * fs size >   16G: 16k clusters
 329                          */
 330                         sect_per_clust = 1;
 331                         if (volume_size_bytes >= 260*1024*1024) {
 332                                 sect_per_clust = 8;
 333                                 /* fight gcc: */
 334                                 /* "error: integer overflow in expression" */
 335                                 /* "error: right shift count >= width of type" */
 336                                 if (sizeof(off_t) > 4) {
 337                                         unsigned t = (volume_size_bytes >> 31 >> 1);
 338                                         if (t >= 8/4)
 339                                                 sect_per_clust = 16;
 340                                         if (t >= 16/4)
 341                                                 sect_per_clust = 32;
 342                                 }
 343                         }
 344                 } else {
 345                         // floppy, loop, or regular file
 346                         int not_floppy = ioctl(dev, FDGETPRM, &param);
 347                         if (not_floppy == 0) {
 348                                 // floppy disk
 349                                 sect_per_track = param.sect;
 350                                 heads = param.head;
 351                                 volume_size_sect = param.size;
 352                                 volume_size_bytes = param.size * SECTOR_SIZE;
 353                         }
 354                         // setup the media descriptor byte
 355                         switch (volume_size_sect) {
 356                         case 2*360:     // 5.25", 2, 9, 40 - 360K
 357                                 media_byte = 0xfd;
 358                                 break;
 359                         case 2*720:     // 3.5", 2, 9, 80 - 720K
 360                         case 2*1200:    // 5.25", 2, 15, 80 - 1200K
 361                                 media_byte = 0xf9;
 362                                 break;
 363                         default:        // anything else
 364                                 if (not_floppy)
 365                                         goto set_cluster_size;
 366                         case 2*1440:    // 3.5", 2, 18, 80 - 1440K
 367                         case 2*2880:    // 3.5", 2, 36, 80 - 2880K
 368                                 media_byte = 0xf0;
 369                                 break;
 370                         }
 371                         // not floppy, but size matches floppy exactly.
 372                         // perhaps it is a floppy image.
 373                         // we already set media_byte as if it is a floppy,
 374                         // now set sect_per_track and heads.
 375                         heads = 2;
 376                         sect_per_track = (unsigned)volume_size_sect / 160;
 377                         if (sect_per_track < 9)
 378                                 sect_per_track = 9;
 379                 }
 380         }
 381
 382         //
 383         // Calculate number of clusters, sectors/cluster, sectors/FAT
 384         // (an initial guess for sect_per_clust should already be set)
 385         //
 386         // "mkdosfs -v -F 32 image5k 5" is the minimum:
 387         // 2 sectors for FATs and 2 data sectors
 388         if ((off_t)(volume_size_sect - reserved_sect) < 4)
 389                 bb_error_msg_and_die("the image is too small for FAT32");
 390         sect_per_fat = 1;
 391         while (1) {
 392                 while (1) {
 393                         int spf_adj;
 394                         uoff_t tcl = (volume_size_sect - reserved_sect - NUM_FATS * sect_per_fat) / sect_per_clust;
 395                         // tcl may be > MAX_CLUST_32 here, but it may be
 396                         // because sect_per_fat is underestimated,
 397                         // and with increased sect_per_fat it still may become
 398                         // <= MAX_CLUST_32. Therefore, we do not check
 399                         // against MAX_CLUST_32, but against a bigger const:
 400                         if (tcl > 0x80ffffff)
 401                                 goto next;
 402                         total_clust = tcl; // fits in uint32_t
 403                         // Every cluster needs 4 bytes in FAT. +2 entries since
 404                         // FAT has space for non-existent clusters 0 and 1.
 405                         // Let's see how many sectors that needs.
 406                         //May overflow at "*4":
 407                         //spf_adj = ((total_clust+2) * 4 + bytes_per_sect-1) / bytes_per_sect - sect_per_fat;
 408                         //Same in the more obscure, non-overflowing form:
 409                         spf_adj = ((total_clust+2) + (bytes_per_sect/4)-1) / (bytes_per_sect/4) - sect_per_fat;
 410 #if 0
 411                         bb_error_msg("sect_per_clust:%u sect_per_fat:%u total_clust:%u",
 412                                         sect_per_clust, sect_per_fat, (int)tcl);
 413                         bb_error_msg("adjust to sect_per_fat:%d", spf_adj);
 414 #endif
 415                         if (spf_adj <= 0) {
 416                                 // do not need to adjust sect_per_fat.
 417                                 // so, was total_clust too big after all?
 418                                 if (total_clust <= MAX_CLUST_32)
 419                                         goto found_total_clust; // no
 420                                 // yes, total_clust is _a bit_ too big
 421                                 goto next;
 422                         }
 423                         // adjust sect_per_fat, go back and recalc total_clust
 424                         // (note: just "sect_per_fat += spf_adj" isn't ok)
 425                         sect_per_fat += ((unsigned)spf_adj / 2) | 1;
 426                 }
 427  next:
 428                 if (sect_per_clust == 128)
 429                         bb_error_msg_and_die("can't make FAT32 with >128 sectors/cluster");
 430                 sect_per_clust *= 2;
 431                 sect_per_fat = (sect_per_fat / 2) | 1;
 432         }
 433  found_total_clust:
 434
 435         //
 436         // Print info
 437         //
 438         if (opts & OPT_v) {
 439                 fprintf(stderr,
 440                         "Device '%s':\n"
 441                         "heads:%u, sectors/track:%u, bytes/sector:%u\n"
 442                         "media descriptor:%02x\n"
 443                         "total sectors:%"OFF_FMT"u, clusters:%u, sectors/cluster:%u\n"
 444                         "FATs:2, sectors/FAT:%u\n"
 445                         "volumeID:%08x, label:'%s'\n",
 446                         device_name,
 447                         heads, sect_per_track, bytes_per_sect,
 448                         (int)media_byte,
 449                         volume_size_sect, (int)total_clust, (int)sect_per_clust,
 450                         sect_per_fat,
 451                         (int)volume_id, volume_label
 452                 );
 453         }
 454
 455         //
 456         // Write filesystem image sequentially (no seeking)
 457         //
 458         {
 459                 // (a | b) is poor man's max(a, b)
 460                 unsigned bufsize = reserved_sect;
 461                 //bufsize |= sect_per_fat; // can be quite large
 462                 bufsize |= 2; // use this instead
 463                 bufsize |= sect_per_clust;
 464                 buf = xzalloc(bufsize * bytes_per_sect);
 465         }
 466
 467         { // boot and fsinfo sectors, and their copies
 468                 struct msdos_boot_sector *boot_blk = (void*)buf;
 469                 struct fat32_fsinfo *info = (void*)(buf + bytes_per_sect);
 470
 471                 strcpy(boot_blk->boot_jump, "\xeb\x58\x90" "mkdosfs"); // system_id[8] included :)
 472                 STORE_LE(boot_blk->bytes_per_sect, bytes_per_sect);
 473                 STORE_LE(boot_blk->sect_per_clust, sect_per_clust);
 474                 STORE_LE(boot_blk->reserved_sect, reserved_sect);
 475                 STORE_LE(boot_blk->fats, 2);
 476                 //STORE_LE(boot_blk->dir_entries, 0); // for FAT32, stays 0
 477                 if (volume_size_sect <= 0xffff)
 478                         STORE_LE(boot_blk->volume_size_sect, volume_size_sect);
 479                 STORE_LE(boot_blk->media_byte, media_byte);
 480                 // wrong: this would make Linux think that it's fat12/16:
 481                 //if (sect_per_fat <= 0xffff)
 482                 //      STORE_LE(boot_blk->sect_per_fat, sect_per_fat);
 483                 // works:
 484                 //STORE_LE(boot_blk->sect_per_fat, 0);
 485                 STORE_LE(boot_blk->sect_per_track, sect_per_track);
 486                 STORE_LE(boot_blk->heads, heads);
 487                 //STORE_LE(boot_blk->hidden, 0);
 488                 STORE_LE(boot_blk->fat32_volume_size_sect, volume_size_sect);
 489                 STORE_LE(boot_blk->fat32_sect_per_fat, sect_per_fat);
 490                 //STORE_LE(boot_blk->fat32_flags, 0);
 491                 //STORE_LE(boot_blk->fat32_version[2], 0,0);
 492                 STORE_LE(boot_blk->fat32_root_cluster, 2);
 493                 STORE_LE(boot_blk->fat32_info_sector, info_sector_number);
 494                 STORE_LE(boot_blk->fat32_backup_boot, backup_boot_sector);
 495                 //STORE_LE(boot_blk->reserved2[3], 0,0,0);
 496                 STORE_LE(boot_blk->vi.ext_boot_sign, 0x29);
 497                 STORE_LE(boot_blk->vi.volume_id32, volume_id);
 498                 strncpy(boot_blk->vi.fs_type, "FAT32   ", sizeof(boot_blk->vi.fs_type));
 499                 strncpy(boot_blk->vi.volume_label, volume_label, sizeof(boot_blk->vi.volume_label));
 500                 memcpy(boot_blk->boot_code, boot_code, sizeof(boot_code));
 501                 STORE_LE(boot_blk->boot_sign, BOOT_SIGN);
 502
 503                 STORE_LE(info->signature1, FAT_FSINFO_SIG1);
 504                 STORE_LE(info->signature2, FAT_FSINFO_SIG2);
 505                 // we've allocated cluster 2 for the root dir
 506                 STORE_LE(info->free_clusters, (total_clust - 1));
 507                 STORE_LE(info->next_cluster, 2);
 508                 STORE_LE(info->boot_sign, BOOT_SIGN);
 509
 510                 // 1st copy
 511                 xwrite(dev, buf, bytes_per_sect * backup_boot_sector);
 512                 // 2nd copy and possibly zero sectors
 513                 xwrite(dev, buf, bytes_per_sect * (reserved_sect - backup_boot_sector));
 514         }
 515
 516         { // file allocation tables
 517                 unsigned i,j;
 518                 unsigned char *fat = (void*)buf;
 519
 520                 memset(buf, 0, bytes_per_sect * 2);
 521                 // initial FAT entries
 522                 MARK_CLUSTER(0, 0x0fffff00 | media_byte);
 523                 MARK_CLUSTER(1, 0xffffffff);
 524                 // mark cluster 2 as EOF (used for root dir)
 525                 MARK_CLUSTER(2, EOF_FAT32);
 526                 for (i = 0; i < NUM_FATS; i++) {
 527                         xwrite(dev, buf, bytes_per_sect);
 528                         for (j = 1; j < sect_per_fat; j++)
 529                                 xwrite(dev, buf + bytes_per_sect, bytes_per_sect);
 530                 }
 531         }
 532
 533         // root directory
 534         // empty directory is just a set of zero bytes
 535         memset(buf, 0, sect_per_clust * bytes_per_sect);
 536         if (volume_label[0]) {
 537                 // create dir entry for volume_label
 538                 struct msdos_dir_entry *de;
 539 #if 0
 540                 struct tm tm;
 541                 uint16_t t, d;
 542 #endif
 543                 de = (void*)buf;
 544                 strncpy(de->name, volume_label, sizeof(de->name));
 545                 STORE_LE(de->attr, ATTR_VOLUME);
 546 #if 0
 547                 localtime_r(&create_time, &tm);
 548                 t = (tm.tm_sec >> 1) + (tm.tm_min << 5) + (tm.tm_hour << 11);
 549                 d = tm.tm_mday + ((tm.tm_mon+1) << 5) + ((tm.tm_year-80) << 9);
 550                 STORE_LE(de->time, t);
 551                 STORE_LE(de->date, d);
 552                 //STORE_LE(de->ctime_cs, 0);
 553                 de->ctime = de->time;
 554                 de->cdate = de->date;
 555                 de->adate = de->date;
 556 #endif
 557         }
 558         xwrite(dev, buf, sect_per_clust * bytes_per_sect);
 559
 560 #if 0
 561         if (opts & OPT_c) {
 562                 uoff_t volume_size_blocks;
 563                 unsigned start_data_sector;
 564                 unsigned start_data_block;
 565                 unsigned badblocks = 0;
 566                 int try, got;
 567                 off_t currently_testing;
 568                 char *blkbuf = xmalloc(BLOCK_SIZE * TEST_BUFFER_BLOCKS);
 569
 570                 volume_size_blocks = (volume_size_bytes >> BLOCK_SIZE_BITS);
 571                 // N.B. the two following vars are in hard sectors, i.e. SECTOR_SIZE byte sectors!
 572                 start_data_sector = (reserved_sect + NUM_FATS * sect_per_fat) * (bytes_per_sect / SECTOR_SIZE);
 573                 start_data_block = (start_data_sector + SECTORS_PER_BLOCK - 1) / SECTORS_PER_BLOCK;
 574
 575                 bb_info_msg("searching for bad blocks ");
 576                 currently_testing = 0;
 577                 try = TEST_BUFFER_BLOCKS;
 578                 while (currently_testing < volume_size_blocks) {
 579                         if (currently_testing + try > volume_size_blocks)
 580                                 try = volume_size_blocks - currently_testing;
 581                         // perform a test on a block. return the number of blocks
 582                         // that could be read successfully.
 583                         // seek to the correct location
 584                         xlseek(dev, currently_testing * BLOCK_SIZE, SEEK_SET);
 585                         // try reading
 586                         got = read(dev, blkbuf, try * BLOCK_SIZE);
 587                         if (got < 0)
 588                                 got = 0;
 589                         if (got & (BLOCK_SIZE - 1))
 590                                 bb_error_msg("unexpected values in do_check: probably bugs");
 591                         got /= BLOCK_SIZE;
 592                         currently_testing += got;
 593                         if (got == try) {
 594                                 try = TEST_BUFFER_BLOCKS;
 595                                 continue;
 596                         }
 597                         try = 1;
 598                         if (currently_testing < start_data_block)
 599                                 bb_error_msg_and_die("bad blocks before data-area: cannot make fs");
 600
 601                         // mark all of the sectors in the block as bad
 602                         for (i = 0; i < SECTORS_PER_BLOCK; i++) {
 603                                 int cluster = (currently_testing * SECTORS_PER_BLOCK + i - start_data_sector) / (int) (sect_per_clust) / (bytes_per_sect / SECTOR_SIZE);
 604                                 if (cluster < 0)
 605                                         bb_error_msg_and_die("invalid cluster number in mark_sector: probably bug!");
 606                                 MARK_CLUSTER(cluster, BAD_FAT32);
 607                         }
 608                         badblocks++;
 609                         currently_testing++;
 610                 }
 611                 free(blkbuf);
 612                 if (badblocks)
 613                         bb_info_msg("%d bad block(s)", badblocks);
 614         }
 615 #endif
 616
 617         // cleanup
 618         if (ENABLE_FEATURE_CLEAN_UP) {
 619                 free(buf);
 620                 close(dev);
 621         }
 622
 623         return 0;
 624 }