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:       select PLATFORM_LINUX
  14//config:       help
  15//config:       Utility to create FAT32 filesystems.
  16//config:
  17//config:config MKFS_VFAT
  18//config:       bool "mkfs.vfat (7.2 kb)"
  19//config:       default y
  20//config:       select PLATFORM_LINUX
  21//config:       help
  22//config:       Alias to "mkdosfs".
  23
  24//                    APPLET_ODDNAME:name       main       location     suid_type     help
  25//applet:IF_MKDOSFS(  APPLET_ODDNAME(mkdosfs,   mkfs_vfat, BB_DIR_SBIN, BB_SUID_DROP, mkfs_vfat))
  26//applet:IF_MKFS_VFAT(APPLET_ODDNAME(mkfs.vfat, mkfs_vfat, BB_DIR_SBIN, BB_SUID_DROP, mkfs_vfat))
  27
  28//kbuild:lib-$(CONFIG_MKDOSFS) += mkfs_vfat.o
  29//kbuild:lib-$(CONFIG_MKFS_VFAT) += mkfs_vfat.o
  30
  31//usage:#define mkfs_vfat_trivial_usage
  32//usage:       "[-v] [-n LABEL] BLOCKDEV [KBYTES]"
  33/* Accepted but ignored:
  34       "[-c] [-C] [-I] [-l bad-block-file] [-b backup-boot-sector] "
  35       "[-m boot-msg-file] [-i volume-id] "
  36       "[-s sectors-per-cluster] [-S logical-sector-size] [-f number-of-FATs] "
  37       "[-h hidden-sectors] [-F fat-size] [-r root-dir-entries] [-R reserved-sectors] "
  38*/
  39//usage:#define mkfs_vfat_full_usage "\n\n"
  40//usage:       "Make a FAT32 filesystem\n"
  41/* //usage:  "\n        -c      Check device for bad blocks" */
  42//usage:     "\n        -v      Verbose"
  43/* //usage:  "\n        -I      Allow to use entire disk device (e.g. /dev/hda)" */
  44//usage:     "\n        -n LBL  Volume label"
  45
  46#include "libbb.h"
  47
  48#include <linux/hdreg.h> /* HDIO_GETGEO */
  49#include <linux/fd.h>    /* FDGETPRM */
  50#include <sys/mount.h>   /* BLKSSZGET */
  51#if !defined(BLKSSZGET)
  52# define BLKSSZGET _IO(0x12, 104)
  53#endif
  54//#include <linux/msdos_fs.h>
  55
  56#define SECTOR_SIZE             512
  57
  58#define SECTORS_PER_BLOCK       (BLOCK_SIZE / SECTOR_SIZE)
  59
  60// M$ says the high 4 bits of a FAT32 FAT entry are reserved
  61#define EOF_FAT32       0x0FFFFFF8
  62#define BAD_FAT32       0x0FFFFFF7
  63#define MAX_CLUST_32    0x0FFFFFF0
  64
  65#define ATTR_VOLUME     8
  66
  67#define NUM_FATS        2
  68
  69/* FAT32 filesystem looks like this:
  70 * sector -nn...-1: "hidden" sectors, all sectors before this partition
  71 * (-h hidden-sectors sets it. Useful only for boot loaders,
  72 *  they need to know _disk_ offset in order to be able to correctly
  73 *  address sectors relative to start of disk)
  74 * sector 0: boot sector
  75 * sector 1: info sector
  76 * sector 2: set aside for boot code which didn't fit into sector 0
  77 * ...(zero-filled sectors)...
  78 * sector B: backup copy of sector 0 [B set by -b backup-boot-sector]
  79 * sector B+1: backup copy of sector 1
  80 * sector B+2: backup copy of sector 2
  81 * ...(zero-filled sectors)...
  82 * sector R: FAT#1 [R set by -R reserved-sectors]
  83 * ...(FAT#1)...
  84 * sector R+fat_size: FAT#2
  85 * ...(FAT#2)...
  86 * sector R+fat_size*2: cluster #2
  87 * ...(cluster #2)...
  88 * sector R+fat_size*2+clust_size: cluster #3
  89 * ...(the rest is filled by clusters till the end)...
  90 */
  91
  92enum {
  93// Perhaps this should remain constant
  94        info_sector_number = 1,
  95// TODO: make these cmdline options
  96// dont forget sanity check: backup_boot_sector + 3 <= reserved_sect
  97        backup_boot_sector = 3,
  98        reserved_sect      = 6,
  99};
 100
 101// how many blocks we try to read while testing
 102#define TEST_BUFFER_BLOCKS      16
 103
 104struct msdos_dir_entry {
 105        char     name[11];       /* 000 name and extension */
 106        uint8_t  attr;           /* 00b attribute bits */
 107        uint8_t  lcase;          /* 00c case for base and extension */
 108        uint8_t  ctime_cs;       /* 00d creation time, centiseconds (0-199) */
 109        uint16_t ctime;          /* 00e creation time */
 110        uint16_t cdate;          /* 010 creation date */
 111        uint16_t adate;          /* 012 last access date */
 112        uint16_t starthi;        /* 014 high 16 bits of cluster in FAT32 */
 113        uint16_t time;           /* 016 time */
 114        uint16_t date;           /* 018 date */
 115        uint16_t start;          /* 01a first cluster */
 116        uint32_t size;           /* 01c file size in bytes */
 117} PACKED;
 118
 119/* Example of boot sector's beginning:
 1200000  eb 58 90 4d 53 57 49 4e  34 2e 31 00 02 08 26 00  |...MSWIN4.1...&.|
 1210010  02 00 00 00 00 f8 00 00  3f 00 ff 00 3f 00 00 00  |........?...?...|
 1220020  54 9b d0 00 0d 34 00 00  00 00 00 00 02 00 00 00  |T....4..........|
 1230030  01 00 06 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
 1240040  80 00 29 71 df 51 e0 4e  4f 20 4e 41 4d 45 20 20  |..)q.Q.NO NAME  |
 1250050  20 20 46 41 54 33 32 20  20 20 33 c9 8e d1 bc f4  |  FAT32   3.....|
 126*/
 127struct msdos_volume_info { /* (offsets are relative to start of boot sector) */
 128        uint8_t  drive_number;    /* 040 BIOS drive number */
 129        uint8_t  reserved;        /* 041 unused */
 130        uint8_t  ext_boot_sign;   /* 042 0x29 if fields below exist (DOS 3.3+) */
 131        uint32_t volume_id32;     /* 043 volume ID number */
 132        char     volume_label[11];/* 047 volume label */
 133        char     fs_type[8];      /* 052 typically "FATnn" */
 134} PACKED;                         /* 05a end. Total size 26 (0x1a) bytes */
 135
 136struct msdos_boot_sector {
 137        /* We use strcpy to fill both, and gcc-4.4.x complains if they are separate */
 138        char     boot_jump_and_sys_id[3+8]; /* 000 short or near jump instruction */
 139        /*char   system_id[8];*/     /* 003 name - can be used to special case partition manager volumes */
 140        uint16_t bytes_per_sect;     /* 00b bytes per logical sector */
 141        uint8_t  sect_per_clust;     /* 00d sectors/cluster */
 142        uint16_t reserved_sect;      /* 00e reserved sectors (sector offset of 1st FAT relative to volume start) */
 143        uint8_t  fats;               /* 010 number of FATs */
 144        uint16_t dir_entries;        /* 011 root directory entries */
 145        uint16_t volume_size_sect;   /* 013 volume size in sectors */
 146        uint8_t  media_byte;         /* 015 media code */
 147        uint16_t sect_per_fat;       /* 016 sectors/FAT */
 148        uint16_t sect_per_track;     /* 018 sectors per track */
 149        uint16_t heads;              /* 01a number of heads */
 150        uint32_t hidden;             /* 01c hidden sectors (sector offset of volume within physical disk) */
 151        uint32_t fat32_volume_size_sect; /* 020 volume size in sectors (if volume_size_sect == 0) */
 152        uint32_t fat32_sect_per_fat; /* 024 sectors/FAT */
 153        uint16_t fat32_flags;        /* 028 bit 8: fat mirroring, low 4: active fat */
 154        uint8_t  fat32_version[2];   /* 02a major, minor filesystem version (I see 0,0) */
 155        uint32_t fat32_root_cluster; /* 02c first cluster in root directory */
 156        uint16_t fat32_info_sector;  /* 030 filesystem info sector (usually 1) */
 157        uint16_t fat32_backup_boot;  /* 032 backup boot sector (usually 6) */
 158        uint32_t reserved2[3];       /* 034 unused */
 159        struct msdos_volume_info vi; /* 040 */
 160        char     boot_code[0x200 - 0x5a - 2]; /* 05a */
 161#define BOOT_SIGN 0xAA55
 162        uint16_t boot_sign;          /* 1fe */
 163} PACKED;
 164
 165#define FAT_FSINFO_SIG1 0x41615252
 166#define FAT_FSINFO_SIG2 0x61417272
 167struct fat32_fsinfo {
 168        uint32_t signature1;         /* 0x52,0x52,0x41,0x61, "RRaA" */
 169        uint32_t reserved1[128 - 8];
 170        uint32_t signature2;         /* 0x72,0x72,0x61,0x41, "rrAa" */
 171        uint32_t free_clusters;      /* free cluster count.  -1 if unknown */
 172        uint32_t next_cluster;       /* most recently allocated cluster */
 173        uint32_t reserved2[3];
 174        uint16_t reserved3;          /* 1fc */
 175        uint16_t boot_sign;          /* 1fe */
 176} PACKED;
 177
 178struct bug_check {
 179        char BUG1[sizeof(struct msdos_dir_entry  ) == 0x20 ? 1 : -1];
 180        char BUG2[sizeof(struct msdos_volume_info) == 0x1a ? 1 : -1];
 181        char BUG3[sizeof(struct msdos_boot_sector) == 0x200 ? 1 : -1];
 182        char BUG4[sizeof(struct fat32_fsinfo     ) == 0x200 ? 1 : -1];
 183};
 184
 185static const char boot_code[] ALIGN1 =
 186        "\x0e"          /* 05a:         push  cs */
 187        "\x1f"          /* 05b:         pop   ds */
 188        "\xbe\x77\x7c"  /*  write_msg:  mov   si, offset message_txt */
 189        "\xac"          /* 05f:         lodsb */
 190        "\x22\xc0"      /* 060:         and   al, al */
 191        "\x74\x0b"      /* 062:         jz    key_press */
 192        "\x56"          /* 064:         push  si */
 193        "\xb4\x0e"      /* 065:         mov   ah, 0eh */
 194        "\xbb\x07\x00"  /* 067:         mov   bx, 0007h */
 195        "\xcd\x10"      /* 06a:         int   10h */
 196        "\x5e"          /* 06c:         pop   si */
 197        "\xeb\xf0"      /* 06d:         jmp   write_msg */
 198        "\x32\xe4"      /*  key_press:  xor   ah, ah */
 199        "\xcd\x16"      /* 071:         int   16h */
 200        "\xcd\x19"      /* 073:         int   19h */
 201        "\xeb\xfe"      /*  foo:        jmp   foo */
 202        /* 077: message_txt: */
 203        "This is not a bootable disk\r\n";
 204
 205
 206#define MARK_CLUSTER(cluster, value) \
 207        ((uint32_t *)fat)[cluster] = SWAP_LE32(value)
 208
 209/* compat:
 210 * mkdosfs 2.11 (12 Mar 2005)
 211 * Usage: mkdosfs [-A] [-c] [-C] [-v] [-I] [-l bad-block-file]
 212 *        [-b backup-boot-sector]
 213 *        [-m boot-msg-file] [-n volume-name] [-i volume-id]
 214 *        [-s sectors-per-cluster] [-S logical-sector-size]
 215 *        [-f number-of-FATs]
 216 *        [-h hidden-sectors] [-F fat-size] [-r root-dir-entries]
 217 *        [-R reserved-sectors]
 218 *        /dev/name [blocks]
 219 */
 220int mkfs_vfat_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 221int mkfs_vfat_main(int argc UNUSED_PARAM, char **argv)
 222{
 223        struct stat st;
 224        const char *volume_label = "";
 225        char *buf;
 226        char *device_name;
 227        uoff_t volume_size_bytes;
 228        uoff_t volume_size_sect;
 229        uint32_t total_clust;
 230        uint32_t volume_id;
 231        int dev;
 232        unsigned bytes_per_sect;
 233        unsigned sect_per_fat;
 234        unsigned opts;
 235        uint16_t sect_per_track;
 236        uint8_t media_byte;
 237        uint8_t sect_per_clust;
 238        uint8_t heads;
 239        enum {
 240                OPT_A = 1 << 0,  // [IGNORED] atari format
 241                OPT_b = 1 << 1,  // [IGNORED] location of backup boot sector
 242                OPT_c = 1 << 2,  // [IGNORED] check filesystem
 243                OPT_C = 1 << 3,  // [IGNORED] create a new file
 244                OPT_f = 1 << 4,  // [IGNORED] number of FATs
 245                OPT_F = 1 << 5,  // [IGNORED, implied 32] choose FAT size
 246                OPT_h = 1 << 6,  // [IGNORED] number of hidden sectors
 247                OPT_I = 1 << 7,  // [IGNORED] don't bark at entire disk devices
 248                OPT_i = 1 << 8,  // [IGNORED] volume ID
 249                OPT_l = 1 << 9,  // [IGNORED] bad block filename
 250                OPT_m = 1 << 10, // [IGNORED] message file
 251                OPT_n = 1 << 11, // volume label
 252                OPT_r = 1 << 12, // [IGNORED] root directory entries
 253                OPT_R = 1 << 13, // [IGNORED] number of reserved sectors
 254                OPT_s = 1 << 14, // [IGNORED] sectors per cluster
 255                OPT_S = 1 << 15, // [IGNORED] sector size
 256                OPT_v = 1 << 16, // verbose
 257        };
 258
 259        opts = getopt32(argv, "^"
 260                "Ab:cCf:F:h:Ii:l:m:n:r:R:s:S:v"
 261                "\0" "-1", //:b+:f+:F+:h+:r+:R+:s+:S+:vv:c--l:l--c
 262                NULL, NULL, NULL, NULL, NULL,
 263                NULL, NULL, &volume_label, NULL, NULL, NULL, NULL);
 264        argv += optind;
 265
 266        // cache device name
 267        device_name = argv[0];
 268        // default volume ID = creation time
 269        volume_id = time(NULL);
 270
 271        dev = xopen(device_name, O_RDWR);
 272        xfstat(dev, &st, device_name);
 273
 274        //
 275        // Get image size and sector size
 276        //
 277        bytes_per_sect = SECTOR_SIZE;
 278        if (!S_ISBLK(st.st_mode)) {
 279                if (!S_ISREG(st.st_mode)) {
 280                        if (!argv[1])
 281                                bb_error_msg_and_die("image size must be specified");
 282                }
 283                // not a block device, skip bad sectors check
 284                opts &= ~OPT_c;
 285        } else {
 286                int min_bytes_per_sect;
 287#if 0
 288                unsigned device_num;
 289                // for true block devices we do check sanity
 290                device_num = st.st_rdev & 0xff3f;
 291                // do we allow to format the whole disk device?
 292                if (!(opts & OPT_I) && (
 293                        device_num == 0x0300 || // hda, hdb
 294                        (device_num & 0xff0f) == 0x0800 || // sd
 295                        device_num == 0x0d00 || // xd
 296                        device_num == 0x1600 )  // hdc, hdd
 297                )
 298                        bb_error_msg_and_die("will not try to make filesystem on full-disk device (use -I if wanted)");
 299                // can't work on mounted filesystems
 300                if (find_mount_point(device_name, 0))
 301                        bb_error_msg_and_die("can't format mounted filesystem");
 302#endif
 303                // get true sector size
 304                // (parameter must be int*, not long* or size_t*)
 305                xioctl(dev, BLKSSZGET, &min_bytes_per_sect);
 306                if (min_bytes_per_sect > SECTOR_SIZE) {
 307                        bytes_per_sect = min_bytes_per_sect;
 308                        bb_error_msg("for this device sector size is %u", min_bytes_per_sect);
 309                }
 310        }
 311        volume_size_bytes = get_volume_size_in_bytes(dev, argv[1], 1024, /*extend:*/ 1);
 312        volume_size_sect = volume_size_bytes / bytes_per_sect;
 313
 314        //
 315        // Find out or guess media parameters
 316        //
 317        media_byte = 0xf8;
 318        heads = 255;
 319        sect_per_track = 63;
 320        sect_per_clust = 1;
 321        {
 322                struct hd_geometry geometry;
 323                // size (in sectors), sect (per track), head
 324                struct floppy_struct param;
 325
 326                // N.B. whether to use HDIO_GETGEO or HDIO_REQ?
 327                if (ioctl(dev, HDIO_GETGEO, &geometry) == 0
 328                 && geometry.sectors
 329                 && geometry.heads
 330                ) {
 331                        // hard drive
 332                        sect_per_track = geometry.sectors;
 333                        heads = geometry.heads;
 334
 335 set_cluster_size:
 336                        /* For FAT32, try to do the same as M$'s format command
 337                         * (see http://www.win.tue.nl/~aeb/linux/fs/fat/fatgen103.pdf p. 20):
 338                         * fs size <= 260M: 0.5k clusters
 339                         * fs size <=   8G: 4k clusters
 340                         * fs size <=  16G: 8k clusters
 341                         * fs size >   16G: 16k clusters
 342                         */
 343                        sect_per_clust = 1;
 344                        if (volume_size_bytes >= 260*1024*1024) {
 345                                sect_per_clust = 8;
 346                                /* fight gcc: */
 347                                /* "error: integer overflow in expression" */
 348                                /* "error: right shift count >= width of type" */
 349                                if (sizeof(off_t) > 4) {
 350                                        unsigned t = (volume_size_bytes >> 31 >> 1);
 351                                        if (t >= 8/4)
 352                                                sect_per_clust = 16;
 353                                        if (t >= 16/4)
 354                                                sect_per_clust = 32;
 355                                }
 356                        }
 357                } else {
 358                        // floppy, loop, or regular file
 359                        int not_floppy = ioctl(dev, FDGETPRM, &param);
 360                        if (not_floppy == 0) {
 361                                // floppy disk
 362                                sect_per_track = param.sect;
 363                                heads = param.head;
 364                                volume_size_sect = param.size;
 365                                volume_size_bytes = param.size * SECTOR_SIZE;
 366                        }
 367                        // setup the media descriptor byte
 368                        switch (volume_size_sect) {
 369                        case 2*360:     // 5.25", 2, 9, 40 - 360K
 370                                media_byte = 0xfd;
 371                                break;
 372                        case 2*720:     // 3.5", 2, 9, 80 - 720K
 373                        case 2*1200:    // 5.25", 2, 15, 80 - 1200K
 374                                media_byte = 0xf9;
 375                                break;
 376                        default:        // anything else
 377                                if (not_floppy)
 378                                        goto set_cluster_size;
 379                        case 2*1440:    // 3.5", 2, 18, 80 - 1440K
 380                        case 2*2880:    // 3.5", 2, 36, 80 - 2880K
 381                                media_byte = 0xf0;
 382                                break;
 383                        }
 384                        // not floppy, but size matches floppy exactly.
 385                        // perhaps it is a floppy image.
 386                        // we already set media_byte as if it is a floppy,
 387                        // now set sect_per_track and heads.
 388                        heads = 2;
 389                        sect_per_track = (unsigned)volume_size_sect / 160;
 390                        if (sect_per_track < 9)
 391                                sect_per_track = 9;
 392                }
 393        }
 394
 395        //
 396        // Calculate number of clusters, sectors/cluster, sectors/FAT
 397        // (an initial guess for sect_per_clust should already be set)
 398        //
 399        // "mkdosfs -v -F 32 image5k 5" is the minimum:
 400        // 2 sectors for FATs and 2 data sectors
 401        if ((off_t)(volume_size_sect - reserved_sect) < 4)
 402                bb_error_msg_and_die("the image is too small for FAT32");
 403        sect_per_fat = 1;
 404        while (1) {
 405                while (1) {
 406                        int spf_adj;
 407                        uoff_t tcl = (volume_size_sect - reserved_sect - NUM_FATS * sect_per_fat) / sect_per_clust;
 408                        // tcl may be > MAX_CLUST_32 here, but it may be
 409                        // because sect_per_fat is underestimated,
 410                        // and with increased sect_per_fat it still may become
 411                        // <= MAX_CLUST_32. Therefore, we do not check
 412                        // against MAX_CLUST_32, but against a bigger const:
 413                        if (tcl > 0x80ffffff)
 414                                goto next;
 415                        total_clust = tcl; // fits in uint32_t
 416                        // Every cluster needs 4 bytes in FAT. +2 entries since
 417                        // FAT has space for non-existent clusters 0 and 1.
 418                        // Let's see how many sectors that needs.
 419                        //May overflow at "*4":
 420                        //spf_adj = ((total_clust+2) * 4 + bytes_per_sect-1) / bytes_per_sect - sect_per_fat;
 421                        //Same in the more obscure, non-overflowing form:
 422                        spf_adj = ((total_clust+2) + (bytes_per_sect/4)-1) / (bytes_per_sect/4) - sect_per_fat;
 423#if 0
 424                        bb_error_msg("sect_per_clust:%u sect_per_fat:%u total_clust:%u",
 425                                        sect_per_clust, sect_per_fat, (int)tcl);
 426                        bb_error_msg("adjust to sect_per_fat:%d", spf_adj);
 427#endif
 428                        if (spf_adj <= 0) {
 429                                // do not need to adjust sect_per_fat.
 430                                // so, was total_clust too big after all?
 431                                if (total_clust <= MAX_CLUST_32)
 432                                        goto found_total_clust; // no
 433                                // yes, total_clust is _a bit_ too big
 434                                goto next;
 435                        }
 436                        // adjust sect_per_fat, go back and recalc total_clust
 437                        // (note: just "sect_per_fat += spf_adj" isn't ok)
 438                        sect_per_fat += ((unsigned)spf_adj / 2) | 1;
 439                }
 440 next:
 441                if (sect_per_clust == 128)
 442                        bb_error_msg_and_die("can't make FAT32 with >128 sectors/cluster");
 443                sect_per_clust *= 2;
 444                sect_per_fat = (sect_per_fat / 2) | 1;
 445        }
 446 found_total_clust:
 447
 448        //
 449        // Print info
 450        //
 451        if (opts & OPT_v) {
 452                fprintf(stderr,
 453                        "Device '%s':\n"
 454                        "heads:%u, sectors/track:%u, bytes/sector:%u\n"
 455                        "media descriptor:%02x\n"
 456                        "total sectors:%"OFF_FMT"u, clusters:%u, sectors/cluster:%u\n"
 457                        "FATs:2, sectors/FAT:%u\n"
 458                        "volumeID:%08x, label:'%s'\n",
 459                        device_name,
 460                        heads, sect_per_track, bytes_per_sect,
 461                        (int)media_byte,
 462                        volume_size_sect, (int)total_clust, (int)sect_per_clust,
 463                        sect_per_fat,
 464                        (int)volume_id, volume_label
 465                );
 466        }
 467
 468        //
 469        // Write filesystem image sequentially (no seeking)
 470        //
 471        {
 472                // (a | b) is poor man's max(a, b)
 473                unsigned bufsize = reserved_sect;
 474                //bufsize |= sect_per_fat; // can be quite large
 475                bufsize |= 2; // use this instead
 476                bufsize |= sect_per_clust;
 477                buf = xzalloc(bufsize * bytes_per_sect);
 478        }
 479
 480        { // boot and fsinfo sectors, and their copies
 481                struct msdos_boot_sector *boot_blk = (void*)buf;
 482                struct fat32_fsinfo *info = (void*)(buf + bytes_per_sect);
 483
 484                strcpy(boot_blk->boot_jump_and_sys_id, "\xeb\x58\x90" "mkdosfs");
 485                STORE_LE(boot_blk->bytes_per_sect, bytes_per_sect);
 486                STORE_LE(boot_blk->sect_per_clust, sect_per_clust);
 487                // cast in needed on big endian to suppress a warning
 488                STORE_LE(boot_blk->reserved_sect, (uint16_t)reserved_sect);
 489                STORE_LE(boot_blk->fats, 2);
 490                //STORE_LE(boot_blk->dir_entries, 0); // for FAT32, stays 0
 491                if (volume_size_sect <= 0xffff)
 492                        STORE_LE(boot_blk->volume_size_sect, volume_size_sect);
 493                STORE_LE(boot_blk->media_byte, media_byte);
 494                // wrong: this would make Linux think that it's fat12/16:
 495                //if (sect_per_fat <= 0xffff)
 496                //      STORE_LE(boot_blk->sect_per_fat, sect_per_fat);
 497                // works:
 498                //STORE_LE(boot_blk->sect_per_fat, 0);
 499                STORE_LE(boot_blk->sect_per_track, sect_per_track);
 500                STORE_LE(boot_blk->heads, heads);
 501                //STORE_LE(boot_blk->hidden, 0);
 502                STORE_LE(boot_blk->fat32_volume_size_sect, volume_size_sect);
 503                STORE_LE(boot_blk->fat32_sect_per_fat, sect_per_fat);
 504                //STORE_LE(boot_blk->fat32_flags, 0);
 505                //STORE_LE(boot_blk->fat32_version[2], 0,0);
 506                STORE_LE(boot_blk->fat32_root_cluster, 2);
 507                STORE_LE(boot_blk->fat32_info_sector, info_sector_number);
 508                STORE_LE(boot_blk->fat32_backup_boot, backup_boot_sector);
 509                //STORE_LE(boot_blk->reserved2[3], 0,0,0);
 510                STORE_LE(boot_blk->vi.ext_boot_sign, 0x29);
 511                STORE_LE(boot_blk->vi.volume_id32, volume_id);
 512                memcpy(boot_blk->vi.fs_type, "FAT32   ", sizeof(boot_blk->vi.fs_type));
 513                strncpy(boot_blk->vi.volume_label, volume_label, sizeof(boot_blk->vi.volume_label));
 514                memcpy(boot_blk->boot_code, boot_code, sizeof(boot_code));
 515                STORE_LE(boot_blk->boot_sign, BOOT_SIGN);
 516
 517                STORE_LE(info->signature1, FAT_FSINFO_SIG1);
 518                STORE_LE(info->signature2, FAT_FSINFO_SIG2);
 519                // we've allocated cluster 2 for the root dir
 520                STORE_LE(info->free_clusters, (total_clust - 1));
 521                STORE_LE(info->next_cluster, 2);
 522                STORE_LE(info->boot_sign, BOOT_SIGN);
 523
 524                // 1st copy
 525                xwrite(dev, buf, bytes_per_sect * backup_boot_sector);
 526                // 2nd copy and possibly zero sectors
 527                xwrite(dev, buf, bytes_per_sect * (reserved_sect - backup_boot_sector));
 528        }
 529
 530        { // file allocation tables
 531                unsigned i,j;
 532                unsigned char *fat = (void*)buf;
 533
 534                memset(buf, 0, bytes_per_sect * 2);
 535                // initial FAT entries
 536                MARK_CLUSTER(0, 0x0fffff00 | media_byte);
 537                MARK_CLUSTER(1, 0xffffffff);
 538                // mark cluster 2 as EOF (used for root dir)
 539                MARK_CLUSTER(2, EOF_FAT32);
 540                for (i = 0; i < NUM_FATS; i++) {
 541                        xwrite(dev, buf, bytes_per_sect);
 542                        for (j = 1; j < sect_per_fat; j++)
 543                                xwrite(dev, buf + bytes_per_sect, bytes_per_sect);
 544                }
 545        }
 546
 547        // root directory
 548        // empty directory is just a set of zero bytes
 549        memset(buf, 0, sect_per_clust * bytes_per_sect);
 550        if (volume_label[0]) {
 551                // create dir entry for volume_label
 552                struct msdos_dir_entry *de;
 553#if 0
 554                struct tm tm_time;
 555                uint16_t t, d;
 556#endif
 557                de = (void*)buf;
 558                strncpy(de->name, volume_label, sizeof(de->name));
 559                STORE_LE(de->attr, ATTR_VOLUME);
 560#if 0
 561                localtime_r(&create_time, &tm_time);
 562                t = (tm_time.tm_sec >> 1) + (tm_time.tm_min << 5) + (tm_time.tm_hour << 11);
 563                d = tm_time.tm_mday + ((tm_time.tm_mon+1) << 5) + ((tm_time.tm_year-80) << 9);
 564                STORE_LE(de->time, t);
 565                STORE_LE(de->date, d);
 566                //STORE_LE(de->ctime_cs, 0);
 567                de->ctime = de->time;
 568                de->cdate = de->date;
 569                de->adate = de->date;
 570#endif
 571        }
 572        xwrite(dev, buf, sect_per_clust * bytes_per_sect);
 573
 574#if 0
 575        if (opts & OPT_c) {
 576                uoff_t volume_size_blocks;
 577                unsigned start_data_sector;
 578                unsigned start_data_block;
 579                unsigned badblocks = 0;
 580                int try, got;
 581                off_t currently_testing;
 582                char *blkbuf = xmalloc(BLOCK_SIZE * TEST_BUFFER_BLOCKS);
 583
 584                volume_size_blocks = (volume_size_bytes >> BLOCK_SIZE_BITS);
 585                // N.B. the two following vars are in hard sectors, i.e. SECTOR_SIZE byte sectors!
 586                start_data_sector = (reserved_sect + NUM_FATS * sect_per_fat) * (bytes_per_sect / SECTOR_SIZE);
 587                start_data_block = (start_data_sector + SECTORS_PER_BLOCK - 1) / SECTORS_PER_BLOCK;
 588
 589                bb_error_msg("searching for bad blocks");
 590                currently_testing = 0;
 591                try = TEST_BUFFER_BLOCKS;
 592                while (currently_testing < volume_size_blocks) {
 593                        if (currently_testing + try > volume_size_blocks)
 594                                try = volume_size_blocks - currently_testing;
 595                        // perform a test on a block. return the number of blocks
 596                        // that could be read successfully.
 597                        // seek to the correct location
 598                        xlseek(dev, currently_testing * BLOCK_SIZE, SEEK_SET);
 599                        // try reading
 600                        got = read(dev, blkbuf, try * BLOCK_SIZE);
 601                        if (got < 0)
 602                                got = 0;
 603                        if (got & (BLOCK_SIZE - 1))
 604                                bb_error_msg("unexpected values in do_check: probably bugs");
 605                        got /= BLOCK_SIZE;
 606                        currently_testing += got;
 607                        if (got == try) {
 608                                try = TEST_BUFFER_BLOCKS;
 609                                continue;
 610                        }
 611                        try = 1;
 612                        if (currently_testing < start_data_block)
 613                                bb_error_msg_and_die("bad blocks before data-area: cannot make fs");
 614
 615                        // mark all of the sectors in the block as bad
 616                        for (i = 0; i < SECTORS_PER_BLOCK; i++) {
 617                                int cluster = (currently_testing * SECTORS_PER_BLOCK + i - start_data_sector) / (int) (sect_per_clust) / (bytes_per_sect / SECTOR_SIZE);
 618                                if (cluster < 0)
 619                                        bb_error_msg_and_die("invalid cluster number in mark_sector: probably bug!");
 620                                MARK_CLUSTER(cluster, BAD_FAT32);
 621                        }
 622                        badblocks++;
 623                        currently_testing++;
 624                }
 625                free(blkbuf);
 626                if (badblocks)
 627                        bb_error_msg("%d bad block(s)", badblocks);
 628        }
 629#endif
 630
 631        // cleanup
 632        if (ENABLE_FEATURE_CLEAN_UP) {
 633                free(buf);
 634                close(dev);
 635        }
 636
 637        return 0;
 638}
 639