LXR busybox/util-linux/mkfs

   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 source tree.
   9 */
  10//config:config MKDOSFS
  11//config:       bool "mkdosfs (7.2 kb)"
  12//config:       default y
  13//config:       help
  14//config:       Utility to create FAT32 filesystems.
  15//config:
  16//config:config MKFS_VFAT
  17//config:       bool "mkfs.vfat (7.2 kb)"
  18//config:       default y
  19//config:       help
  20//config:       Alias to "mkdosfs".
  21
  22//                    APPLET_ODDNAME:name       main       location     suid_type     help
  23//applet:IF_MKDOSFS(  APPLET_ODDNAME(mkdosfs,   mkfs_vfat, BB_DIR_SBIN, BB_SUID_DROP, mkfs_vfat))
  24//applet:IF_MKFS_VFAT(APPLET_ODDNAME(mkfs.vfat, mkfs_vfat, BB_DIR_SBIN, BB_SUID_DROP, mkfs_vfat))
  25
  26//kbuild:lib-$(CONFIG_MKDOSFS) += mkfs_vfat.o
  27//kbuild:lib-$(CONFIG_MKFS_VFAT) += mkfs_vfat.o
  28
  29//usage:#define mkfs_vfat_trivial_usage
  30//usage:       "[-v] [-n LABEL] BLOCKDEV [KBYTES]"
  31/* Accepted but ignored:
  32       "[-c] [-C] [-I] [-l bad-block-file] [-b backup-boot-sector] "
  33       "[-m boot-msg-file] [-i volume-id] "
  34       "[-s sectors-per-cluster] [-S logical-sector-size] [-f number-of-FATs] "
  35       "[-h hidden-sectors] [-F fat-size] [-r root-dir-entries] [-R reserved-sectors] "
  36*/
  37//usage:#define mkfs_vfat_full_usage "\n\n"
  38//usage:       "Make a FAT32 filesystem\n"
  39/* //usage:  "\n        -c      Check device for bad blocks" */
  40//usage:     "\n        -v      Verbose"
  41/* //usage:  "\n        -I      Allow to use entire disk device (e.g. /dev/hda)" */
  42//usage:     "\n        -n LBL  Volume label"
  43
  44#include "libbb.h"
  45
  46#include <linux/hdreg.h> /* HDIO_GETGEO */
  47#include <linux/fd.h>    /* FDGETPRM */
  48#include <sys/mount.h>   /* BLKSSZGET */
  49#if !defined(BLKSSZGET)
  50# define BLKSSZGET _IO(0x12, 104)
  51#endif
  52//#include <linux/msdos_fs.h>
  53
  54#define SECTOR_SIZE             512
  55
  56#define SECTORS_PER_BLOCK       (BLOCK_SIZE / SECTOR_SIZE)
  57
  58// M$ says the high 4 bits of a FAT32 FAT entry are reserved
  59#define EOF_FAT32       0x0FFFFFF8
  60#define BAD_FAT32       0x0FFFFFF7
  61#define MAX_CLUST_32    0x0FFFFFF0
  62
  63#define ATTR_VOLUME     8
  64
  65#define NUM_FATS        2
  66
  67/* FAT32 filesystem looks like this:
  68 * sector -nn...-1: "hidden" sectors, all sectors before this partition
  69 * (-h hidden-sectors sets it. Useful only for boot loaders,
  70 *  they need to know _disk_ offset in order to be able to correctly
  71 *  address sectors relative to start of disk)
  72 * sector 0: boot sector
  73 * sector 1: info sector
  74 * sector 2: set aside for boot code which didn't fit into sector 0
  75 * ...(zero-filled sectors)...
  76 * sector B: backup copy of sector 0 [B set by -b backup-boot-sector]
  77 * sector B+1: backup copy of sector 1
  78 * sector B+2: backup copy of sector 2
  79 * ...(zero-filled sectors)...
  80 * sector R: FAT#1 [R set by -R reserved-sectors]
  81 * ...(FAT#1)...
  82 * sector R+fat_size: FAT#2
  83 * ...(FAT#2)...
  84 * sector R+fat_size*2: cluster #2
  85 * ...(cluster #2)...
  86 * sector R+fat_size*2+clust_size: cluster #3
  87 * ...(the rest is filled by clusters till the end)...
  88 */
  89
  90enum {
  91// Perhaps this should remain constant
  92        info_sector_number = 1,
  93// TODO: make these cmdline options
  94// dont forget sanity check: backup_boot_sector + 3 <= reserved_sect
  95        backup_boot_sector = 3,
  96        reserved_sect      = 6,
  97};
  98
  99// how many blocks we try to read while testing
 100#define TEST_BUFFER_BLOCKS      16
 101
 102struct msdos_dir_entry {
 103        char     name[11];       /* 000 name and extension */
 104        uint8_t  attr;           /* 00b attribute bits */
 105        uint8_t  lcase;          /* 00c case for base and extension */
 106        uint8_t  ctime_cs;       /* 00d creation time, centiseconds (0-199) */
 107        uint16_t ctime;          /* 00e creation time */
 108        uint16_t cdate;          /* 010 creation date */
 109        uint16_t adate;          /* 012 last access date */
 110        uint16_t starthi;        /* 014 high 16 bits of cluster in FAT32 */
 111        uint16_t time;           /* 016 time */
 112        uint16_t date;           /* 018 date */
 113        uint16_t start;          /* 01a first cluster */
 114        uint32_t size;           /* 01c file size in bytes */
 115} PACKED;
 116
 117/* Example of boot sector's beginning:
 1180000  eb 58 90 4d 53 57 49 4e  34 2e 31 00 02 08 26 00  |...MSWIN4.1...&.|
 1190010  02 00 00 00 00 f8 00 00  3f 00 ff 00 3f 00 00 00  |........?...?...|
 1200020  54 9b d0 00 0d 34 00 00  00 00 00 00 02 00 00 00  |T....4..........|
 1210030  01 00 06 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
 1220040  80 00 29 71 df 51 e0 4e  4f 20 4e 41 4d 45 20 20  |..)q.Q.NO NAME  |
 1230050  20 20 46 41 54 33 32 20  20 20 33 c9 8e d1 bc f4  |  FAT32   3.....|
 124*/
 125struct msdos_volume_info { /* (offsets are relative to start of boot sector) */
 126        uint8_t  drive_number;    /* 040 BIOS drive number */
 127        uint8_t  reserved;        /* 041 unused */
 128        uint8_t  ext_boot_sign;   /* 042 0x29 if fields below exist (DOS 3.3+) */
 129        uint32_t volume_id32;     /* 043 volume ID number */
 130        char     volume_label[11];/* 047 volume label */
 131        char     fs_type[8];      /* 052 typically "FATnn" */
 132} PACKED;                         /* 05a end. Total size 26 (0x1a) bytes */
 133
 134struct msdos_boot_sector {
 135        /* We use strcpy to fill both, and gcc-4.4.x complains if they are separate */
 136        char     boot_jump_and_sys_id[3+8]; /* 000 short or near jump instruction */
 137        /*char   system_id[8];*/     /* 003 name - can be used to special case partition manager volumes */
 138        uint16_t bytes_per_sect;     /* 00b bytes per logical sector */
 139        uint8_t  sect_per_clust;     /* 00d sectors/cluster */
 140        uint16_t reserved_sect;      /* 00e reserved sectors (sector offset of 1st FAT relative to volume start) */
 141        uint8_t  fats;               /* 010 number of FATs */
 142        uint16_t dir_entries;        /* 011 root directory entries */
 143        uint16_t volume_size_sect;   /* 013 volume size in sectors */
 144        uint8_t  media_byte;         /* 015 media code */
 145        uint16_t sect_per_fat;       /* 016 sectors/FAT */
 146        uint16_t sect_per_track;     /* 018 sectors per track */
 147        uint16_t heads;              /* 01a number of heads */
 148        uint32_t hidden;             /* 01c hidden sectors (sector offset of volume within physical disk) */
 149        uint32_t fat32_volume_size_sect; /* 020 volume size in sectors (if volume_size_sect == 0) */
 150        uint32_t fat32_sect_per_fat; /* 024 sectors/FAT */
 151        uint16_t fat32_flags;        /* 028 bit 8: fat mirroring, low 4: active fat */
 152        uint8_t  fat32_version[2];   /* 02a major, minor filesystem version (I see 0,0) */
 153        uint32_t fat32_root_cluster; /* 02c first cluster in root directory */
 154        uint16_t fat32_info_sector;  /* 030 filesystem info sector (usually 1) */
 155        uint16_t fat32_backup_boot;  /* 032 backup boot sector (usually 6) */
 156        uint32_t reserved2[3];       /* 034 unused */
 157        struct msdos_volume_info vi; /* 040 */
 158        char     boot_code[0x200 - 0x5a - 2]; /* 05a */
 159#define BOOT_SIGN 0xAA55
 160        uint16_t boot_sign;          /* 1fe */
 161} PACKED;
 162
 163#define FAT_FSINFO_SIG1 0x41615252
 164#define FAT_FSINFO_SIG2 0x61417272
 165struct fat32_fsinfo {
 166        uint32_t signature1;         /* 0x52,0x52,0x41,0x61, "RRaA" */
 167        uint32_t reserved1[128 - 8];
 168        uint32_t signature2;         /* 0x72,0x72,0x61,0x41, "rrAa" */
 169        uint32_t free_clusters;      /* free cluster count.  -1 if unknown */
 170        uint32_t next_cluster;       /* most recently allocated cluster */
 171        uint32_t reserved2[3];
 172        uint16_t reserved3;          /* 1fc */
 173        uint16_t boot_sign;          /* 1fe */
 174} PACKED;
 175
 176struct bug_check {
 177        char BUG1[sizeof(struct msdos_dir_entry  ) == 0x20 ? 1 : -1];
 178        char BUG2[sizeof(struct msdos_volume_info) == 0x1a ? 1 : -1];
 179        char BUG3[sizeof(struct msdos_boot_sector) == 0x200 ? 1 : -1];
 180        char BUG4[sizeof(struct fat32_fsinfo     ) == 0x200 ? 1 : -1];
 181};
 182
 183static const char boot_code[] ALIGN1 =
 184        "\x0e"          /* 05a:         push  cs */
 185        "\x1f"          /* 05b:         pop   ds */
 186        "\xbe\x77\x7c"  /*  write_msg:  mov   si, offset message_txt */
 187        "\xac"          /* 05f:         lodsb */
 188        "\x22\xc0"      /* 060:         and   al, al */
 189        "\x74\x0b"      /* 062:         jz    key_press */
 190        "\x56"          /* 064:         push  si */
 191        "\xb4\x0e"      /* 065:         mov   ah, 0eh */
 192        "\xbb\x07\x00"  /* 067:         mov   bx, 0007h */
 193        "\xcd\x10"      /* 06a:         int   10h */
 194        "\x5e"          /* 06c:         pop   si */
 195        "\xeb\xf0"      /* 06d:         jmp   write_msg */
 196        "\x32\xe4"      /*  key_press:  xor   ah, ah */
 197        "\xcd\x16"      /* 071:         int   16h */
 198        "\xcd\x19"      /* 073:         int   19h */
 199        "\xeb\xfe"      /*  foo:        jmp   foo */
 200        /* 077: message_txt: */
 201        "This is not a bootable disk\r\n";
 202
 203
 204#define MARK_CLUSTER(cluster, value) \
 205        ((uint32_t *)fat)[cluster] = SWAP_LE32(value)
 206
 207/* compat:
 208 * mkdosfs 2.11 (12 Mar 2005)
 209 * Usage: mkdosfs [-A] [-c] [-C] [-v] [-I] [-l bad-block-file]
 210 *        [-b backup-boot-sector]
 211 *        [-m boot-msg-file] [-n volume-name] [-i volume-id]
 212 *        [-s sectors-per-cluster] [-S logical-sector-size]
 213 *        [-f number-of-FATs]
 214 *        [-h hidden-sectors] [-F fat-size] [-r root-dir-entries]
 215 *        [-R reserved-sectors]
 216 *        /dev/name [blocks]
 217 */
 218int mkfs_vfat_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 219int mkfs_vfat_main(int argc UNUSED_PARAM, char **argv)
 220{
 221        struct stat st;
 222        const char *volume_label = "";
 223        char *buf;
 224        char *device_name;
 225        uoff_t volume_size_bytes;
 226        uoff_t volume_size_sect;
 227        uint32_t total_clust;
 228        uint32_t volume_id;
 229        int dev;
 230        unsigned bytes_per_sect;
 231        unsigned sect_per_fat;
 232        unsigned opts;
 233        uint16_t sect_per_track;
 234        uint8_t media_byte;
 235        uint8_t sect_per_clust;
 236        uint8_t heads;
 237        enum {
 238                OPT_A = 1 << 0,  // [IGNORED] atari format
 239                OPT_b = 1 << 1,  // [IGNORED] location of backup boot sector
 240                OPT_c = 1 << 2,  // [IGNORED] check filesystem
 241                OPT_C = 1 << 3,  // [IGNORED] create a new file
 242                OPT_f = 1 << 4,  // [IGNORED] number of FATs
 243                OPT_F = 1 << 5,  // [IGNORED, implied 32] choose FAT size
 244                OPT_h = 1 << 6,  // [IGNORED] number of hidden sectors
 245                OPT_I = 1 << 7,  // [IGNORED] don't bark at entire disk devices
 246                OPT_i = 1 << 8,  // [IGNORED] volume ID
 247                OPT_l = 1 << 9,  // [IGNORED] bad block filename
 248                OPT_m = 1 << 10, // [IGNORED] message file
 249                OPT_n = 1 << 11, // volume label
 250                OPT_r = 1 << 12, // [IGNORED] root directory entries
 251                OPT_R = 1 << 13, // [IGNORED] number of reserved sectors
 252                OPT_s = 1 << 14, // [IGNORED] sectors per cluster
 253                OPT_S = 1 << 15, // [IGNORED] sector size
 254                OPT_v = 1 << 16, // verbose
 255        };
 256
 257        opts = getopt32(argv, "^"
 258                "Ab:cCf:F:h:Ii:l:m:n:r:R:s:S:v"
 259                "\0" "-1", //:b+:f+:F+:h+:r+:R+:s+:S+:vv:c--l:l--c
 260                NULL, NULL, NULL, NULL, NULL,
 261                NULL, NULL, &volume_label, NULL, NULL, NULL, NULL);
 262        argv += optind;
 263
 264        // cache device name
 265        device_name = argv[0];
 266        // default volume ID = creation time
 267        volume_id = time(NULL);
 268
 269        dev = xopen(device_name, O_RDWR);
 270        xfstat(dev, &st, device_name);
 271
 272        //
 273        // Get image size and sector size
 274        //
 275        bytes_per_sect = SECTOR_SIZE;
 276        if (!S_ISBLK(st.st_mode)) {
 277                if (!S_ISREG(st.st_mode)) {
 278                        if (!argv[1])
 279                                bb_simple_error_msg_and_die("image size must be specified");
 280                }
 281                // not a block device, skip bad sectors check
 282                opts &= ~OPT_c;
 283        } else {
 284                int min_bytes_per_sect;
 285#if 0
 286                unsigned device_num;
 287                // for true block devices we do check sanity
 288                device_num = st.st_rdev & 0xff3f;
 289                // do we allow to format the whole disk device?
 290                if (!(opts & OPT_I) && (
 291                        device_num == 0x0300 || // hda, hdb
 292                        (device_num & 0xff0f) == 0x0800 || // sd
 293                        device_num == 0x0d00 || // xd
 294                        device_num == 0x1600 )  // hdc, hdd
 295                )
 296                        bb_error_msg_and_die("will not try to make filesystem on full-disk device (use -I if wanted)");
 297                // can't work on mounted filesystems
 298                if (find_mount_point(device_name, 0))
 299                        bb_error_msg_and_die("can't format mounted filesystem");
 300#endif
 301                // get true sector size
 302                // (parameter must be int*, not long* or size_t*)
 303                xioctl(dev, BLKSSZGET, &min_bytes_per_sect);
 304                if (min_bytes_per_sect > SECTOR_SIZE) {
 305                        bytes_per_sect = min_bytes_per_sect;
 306                        bb_error_msg("for this device sector size is %u", min_bytes_per_sect);
 307                }
 308        }
 309        volume_size_bytes = get_volume_size_in_bytes(dev, argv[1], 1024, /*extend:*/ 1);
 310        volume_size_sect = volume_size_bytes / bytes_per_sect;
 311
 312        //
 313        // Find out or guess media parameters
 314        //
 315        media_byte = 0xf8;
 316        heads = 255;
 317        sect_per_track = 63;
 318        sect_per_clust = 1;
 319        {
 320                struct hd_geometry geometry;
 321                // size (in sectors), sect (per track), head
 322                struct floppy_struct param;
 323
 324                // N.B. whether to use HDIO_GETGEO or HDIO_REQ?
 325                if (ioctl(dev, HDIO_GETGEO, &geometry) == 0
 326                 && geometry.sectors
 327                 && geometry.heads
 328                ) {
 329                        // hard drive
 330                        sect_per_track = geometry.sectors;
 331                        heads = geometry.heads;
 332
 333 set_cluster_size:
 334                        /* For FAT32, try to do the same as M$'s format command
 335                         * (see http://www.win.tue.nl/~aeb/linux/fs/fat/fatgen103.pdf p. 20):
 336                         * fs size <= 260M: 0.5k clusters
 337                         * fs size <=   8G: 4k clusters
 338                         * fs size <=  16G: 8k clusters
 339                         * fs size >   16G: 16k clusters
 340                         */
 341                        sect_per_clust = 1;
 342                        if (volume_size_bytes >= 260*1024*1024) {
 343                                sect_per_clust = 8;
 344                                /* fight gcc: */
 345                                /* "error: integer overflow in expression" */
 346                                /* "error: right shift count >= width of type" */
 347                                if (sizeof(off_t) > 4) {
 348                                        unsigned t = (volume_size_bytes >> 31 >> 1);
 349                                        if (t >= 8/4)
 350                                                sect_per_clust = 16;
 351                                        if (t >= 16/4)
 352                                                sect_per_clust = 32;
 353                                }
 354                        }
 355                } else {
 356                        // floppy, loop, or regular file
 357                        int not_floppy = ioctl(dev, FDGETPRM, &param);
 358                        if (not_floppy == 0) {
 359                                // floppy disk
 360                                sect_per_track = param.sect;
 361                                heads = param.head;
 362                                volume_size_sect = param.size;
 363                                volume_size_bytes = param.size * SECTOR_SIZE;
 364                        }
 365                        // setup the media descriptor byte
 366                        switch (volume_size_sect) {
 367                        case 2*360:     // 5.25", 2, 9, 40 - 360K
 368                                media_byte = 0xfd;
 369                                break;
 370                        case 2*720:     // 3.5", 2, 9, 80 - 720K
 371                        case 2*1200:    // 5.25", 2, 15, 80 - 1200K
 372                                media_byte = 0xf9;
 373                                break;
 374                        default:        // anything else
 375                                if (not_floppy)
 376                                        goto set_cluster_size;
 377                        case 2*1440:    // 3.5", 2, 18, 80 - 1440K
 378                        case 2*2880:    // 3.5", 2, 36, 80 - 2880K
 379                                media_byte = 0xf0;
 380                                break;
 381                        }
 382                        // not floppy, but size matches floppy exactly.
 383                        // perhaps it is a floppy image.
 384                        // we already set media_byte as if it is a floppy,
 385                        // now set sect_per_track and heads.
 386                        heads = 2;
 387                        sect_per_track = (unsigned)volume_size_sect / 160;
 388                        if (sect_per_track < 9)
 389                                sect_per_track = 9;
 390                }
 391        }
 392
 393        //
 394        // Calculate number of clusters, sectors/cluster, sectors/FAT
 395        // (an initial guess for sect_per_clust should already be set)
 396        //
 397        // "mkdosfs -v -F 32 image5k 5" is the minimum:
 398        // 2 sectors for FATs and 2 data sectors
 399        if ((off_t)(volume_size_sect - reserved_sect) < 4)
 400                bb_simple_error_msg_and_die("the image is too small for FAT32");
 401        sect_per_fat = 1;
 402        while (1) {
 403                while (1) {
 404                        int spf_adj;
 405                        uoff_t tcl = (volume_size_sect - reserved_sect - NUM_FATS * sect_per_fat) / sect_per_clust;
 406                        // tcl may be > MAX_CLUST_32 here, but it may be
 407                        // because sect_per_fat is underestimated,
 408                        // and with increased sect_per_fat it still may become
 409                        // <= MAX_CLUST_32. Therefore, we do not check
 410                        // against MAX_CLUST_32, but against a bigger const:
 411                        if (tcl > 0x80ffffff)
 412                                goto next;
 413                        total_clust = tcl; // fits in uint32_t
 414                        // Every cluster needs 4 bytes in FAT. +2 entries since
 415                        // FAT has space for non-existent clusters 0 and 1.
 416                        // Let's see how many sectors that needs.
 417                        //May overflow at "*4":
 418                        //spf_adj = ((total_clust+2) * 4 + bytes_per_sect-1) / bytes_per_sect - sect_per_fat;
 419                        //Same in the more obscure, non-overflowing form:
 420                        spf_adj = ((total_clust+2) + (bytes_per_sect/4)-1) / (bytes_per_sect/4) - sect_per_fat;
 421#if 0
 422                        bb_error_msg("sect_per_clust:%u sect_per_fat:%u total_clust:%u",
 423                                        sect_per_clust, sect_per_fat, (int)tcl);
 424                        bb_error_msg("adjust to sect_per_fat:%d", spf_adj);
 425#endif
 426                        if (spf_adj <= 0) {
 427                                // do not need to adjust sect_per_fat.
 428                                // so, was total_clust too big after all?
 429                                if (total_clust <= MAX_CLUST_32)
 430                                        goto found_total_clust; // no
 431                                // yes, total_clust is _a bit_ too big
 432                                goto next;
 433                        }
 434                        // adjust sect_per_fat, go back and recalc total_clust
 435                        // (note: just "sect_per_fat += spf_adj" isn't ok)
 436                        sect_per_fat += ((unsigned)spf_adj / 2) | 1;
 437                }
 438 next:
 439                if (sect_per_clust == 128)
 440                        bb_simple_error_msg_and_die("can't make FAT32 with >128 sectors/cluster");
 441                sect_per_clust *= 2;
 442                sect_per_fat = (sect_per_fat / 2) | 1;
 443        }
 444 found_total_clust:
 445
 446        //
 447        // Print info
 448        //
 449        if (opts & OPT_v) {
 450                fprintf(stderr,
 451                        "Device '%s':\n"
 452                        "heads:%u, sectors/track:%u, bytes/sector:%u\n"
 453                        "media descriptor:%02x\n"
 454                        "total sectors:%"OFF_FMT"u, clusters:%u, sectors/cluster:%u\n"
 455                        "FATs:2, sectors/FAT:%u\n"
 456                        "volumeID:%08x, label:'%s'\n",
 457                        device_name,
 458                        heads, sect_per_track, bytes_per_sect,
 459                        (int)media_byte,
 460                        volume_size_sect, (int)total_clust, (int)sect_per_clust,
 461                        sect_per_fat,
 462                        (int)volume_id, volume_label
 463                );
 464        }
 465
 466        //
 467        // Write filesystem image sequentially (no seeking)
 468        //
 469        {
 470                // (a | b) is poor man's max(a, b)
 471                unsigned bufsize = reserved_sect;
 472                //bufsize |= sect_per_fat; // can be quite large
 473                bufsize |= 2; // use this instead
 474                bufsize |= sect_per_clust;
 475                buf = xzalloc(bufsize * bytes_per_sect);
 476        }
 477
 478        { // boot and fsinfo sectors, and their copies
 479                struct msdos_boot_sector *boot_blk = (void*)buf;
 480                struct fat32_fsinfo *info = (void*)(buf + bytes_per_sect);
 481
 482                strcpy(boot_blk->boot_jump_and_sys_id, "\xeb\x58\x90" "mkdosfs");
 483                STORE_LE(boot_blk->bytes_per_sect, bytes_per_sect);
 484                STORE_LE(boot_blk->sect_per_clust, sect_per_clust);
 485                // cast in needed on big endian to suppress a warning
 486                STORE_LE(boot_blk->reserved_sect, (uint16_t)reserved_sect);
 487                STORE_LE(boot_blk->fats, 2);
 488                //STORE_LE(boot_blk->dir_entries, 0); // for FAT32, stays 0
 489                if (volume_size_sect <= 0xffff)
 490                        STORE_LE(boot_blk->volume_size_sect, volume_size_sect);
 491                STORE_LE(boot_blk->media_byte, media_byte);
 492                // wrong: this would make Linux think that it's fat12/16:
 493                //if (sect_per_fat <= 0xffff)
 494                //      STORE_LE(boot_blk->sect_per_fat, sect_per_fat);
 495                // works:
 496                //STORE_LE(boot_blk->sect_per_fat, 0);
 497                STORE_LE(boot_blk->sect_per_track, sect_per_track);
 498                STORE_LE(boot_blk->heads, heads);
 499                //STORE_LE(boot_blk->hidden, 0);
 500                STORE_LE(boot_blk->fat32_volume_size_sect, volume_size_sect);
 501                STORE_LE(boot_blk->fat32_sect_per_fat, sect_per_fat);
 502                //STORE_LE(boot_blk->fat32_flags, 0);
 503                //STORE_LE(boot_blk->fat32_version[2], 0,0);
 504                STORE_LE(boot_blk->fat32_root_cluster, 2);
 505                STORE_LE(boot_blk->fat32_info_sector, info_sector_number);
 506                STORE_LE(boot_blk->fat32_backup_boot, backup_boot_sector);
 507                //STORE_LE(boot_blk->reserved2[3], 0,0,0);
 508                STORE_LE(boot_blk->vi.ext_boot_sign, 0x29);
 509                STORE_LE(boot_blk->vi.volume_id32, volume_id);
 510                memcpy(boot_blk->vi.fs_type, "FAT32   ", sizeof(boot_blk->vi.fs_type));
 511                strncpy(boot_blk->vi.volume_label, volume_label, sizeof(boot_blk->vi.volume_label));
 512                memcpy(boot_blk->boot_code, boot_code, sizeof(boot_code));
 513                STORE_LE(boot_blk->boot_sign, BOOT_SIGN);
 514
 515                STORE_LE(info->signature1, FAT_FSINFO_SIG1);
 516                STORE_LE(info->signature2, FAT_FSINFO_SIG2);
 517                // we've allocated cluster 2 for the root dir
 518                STORE_LE(info->free_clusters, (total_clust - 1));
 519                STORE_LE(info->next_cluster, 2);
 520                STORE_LE(info->boot_sign, BOOT_SIGN);
 521
 522                // 1st copy
 523                xwrite(dev, buf, bytes_per_sect * backup_boot_sector);
 524                // 2nd copy and possibly zero sectors
 525                xwrite(dev, buf, bytes_per_sect * (reserved_sect - backup_boot_sector));
 526        }
 527
 528        { // file allocation tables
 529                unsigned i,j;
 530                unsigned char *fat = (void*)buf;
 531
 532                memset(buf, 0, bytes_per_sect * 2);
 533                // initial FAT entries
 534                MARK_CLUSTER(0, 0x0fffff00 | media_byte);
 535                MARK_CLUSTER(1, 0xffffffff);
 536                // mark cluster 2 as EOF (used for root dir)
 537                MARK_CLUSTER(2, EOF_FAT32);
 538                for (i = 0; i < NUM_FATS; i++) {
 539                        xwrite(dev, buf, bytes_per_sect);
 540                        for (j = 1; j < sect_per_fat; j++)
 541                                xwrite(dev, buf + bytes_per_sect, bytes_per_sect);
 542                }
 543        }
 544
 545        // root directory
 546        // empty directory is just a set of zero bytes
 547        memset(buf, 0, sect_per_clust * bytes_per_sect);
 548        if (volume_label[0]) {
 549                // create dir entry for volume_label
 550                struct msdos_dir_entry *de;
 551#if 0
 552                struct tm tm_time;
 553                uint16_t t, d;
 554#endif
 555                de = (void*)buf;
 556                strncpy(de->name, volume_label, sizeof(de->name));
 557                STORE_LE(de->attr, ATTR_VOLUME);
 558#if 0
 559                localtime_r(&create_time, &tm_time);
 560                t = (tm_time.tm_sec >> 1) + (tm_time.tm_min << 5) + (tm_time.tm_hour << 11);
 561                d = tm_time.tm_mday + ((tm_time.tm_mon+1) << 5) + ((tm_time.tm_year-80) << 9);
 562                STORE_LE(de->time, t);
 563                STORE_LE(de->date, d);
 564                //STORE_LE(de->ctime_cs, 0);
 565                de->ctime = de->time;
 566                de->cdate = de->date;
 567                de->adate = de->date;
 568#endif
 569        }
 570        xwrite(dev, buf, sect_per_clust * bytes_per_sect);
 571
 572#if 0
 573        if (opts & OPT_c) {
 574                uoff_t volume_size_blocks;
 575                unsigned start_data_sector;
 576                unsigned start_data_block;
 577                unsigned badblocks = 0;
 578                int try, got;
 579                off_t currently_testing;
 580                char *blkbuf = xmalloc(BLOCK_SIZE * TEST_BUFFER_BLOCKS);
 581
 582                volume_size_blocks = (volume_size_bytes >> BLOCK_SIZE_BITS);
 583                // N.B. the two following vars are in hard sectors, i.e. SECTOR_SIZE byte sectors!
 584                start_data_sector = (reserved_sect + NUM_FATS * sect_per_fat) * (bytes_per_sect / SECTOR_SIZE);
 585                start_data_block = (start_data_sector + SECTORS_PER_BLOCK - 1) / SECTORS_PER_BLOCK;
 586
 587                bb_error_msg("searching for bad blocks");
 588                currently_testing = 0;
 589                try = TEST_BUFFER_BLOCKS;
 590                while (currently_testing < volume_size_blocks) {
 591                        if (currently_testing + try > volume_size_blocks)
 592                                try = volume_size_blocks - currently_testing;
 593                        // perform a test on a block. return the number of blocks
 594                        // that could be read successfully.
 595                        // seek to the correct location
 596                        xlseek(dev, currently_testing * BLOCK_SIZE, SEEK_SET);
 597                        // try reading
 598                        got = read(dev, blkbuf, try * BLOCK_SIZE);
 599                        if (got < 0)
 600                                got = 0;
 601                        if (got & (BLOCK_SIZE - 1))
 602                                bb_error_msg("unexpected values in do_check: probably bugs");
 603                        got /= BLOCK_SIZE;
 604                        currently_testing += got;
 605                        if (got == try) {
 606                                try = TEST_BUFFER_BLOCKS;
 607                                continue;
 608                        }
 609                        try = 1;
 610                        if (currently_testing < start_data_block)
 611                                bb_error_msg_and_die("bad blocks before data-area: cannot make fs");
 612
 613                        // mark all of the sectors in the block as bad
 614                        for (i = 0; i < SECTORS_PER_BLOCK; i++) {
 615                                int cluster = (currently_testing * SECTORS_PER_BLOCK + i - start_data_sector) / (int) (sect_per_clust) / (bytes_per_sect / SECTOR_SIZE);
 616                                if (cluster < 0)
 617                                        bb_error_msg_and_die("invalid cluster number in mark_sector: probably bug!");
 618                                MARK_CLUSTER(cluster, BAD_FAT32);
 619                        }
 620                        badblocks++;
 621                        currently_testing++;
 622                }
 623                free(blkbuf);
 624                if (badblocks)
 625                        bb_error_msg("%d bad block(s)", badblocks);
 626        }
 627#endif
 628
 629        // cleanup
 630        if (ENABLE_FEATURE_CLEAN_UP) {
 631                free(buf);
 632                close(dev);
 633        }
 634
 635        return 0;
 636}
 637