xref: /system/core/toolbox/newfs_msdos.c

/*
 * Copyright (c) 1998 Robert Nordier
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
 * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
 * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef lint
static const char rcsid[] =
        "$FreeBSD: src/sbin/newfs_msdos/newfs_msdos.c,v 1.33 2009/04/11 14:56:29 ed Exp $";
#endif /* not lint */

#include <sys/param.h>

#ifndef ANDROID
#include <sys/fdcio.h>
#include <sys/disk.h>
#include <sys/disklabel.h>
#include <sys/mount.h>
#else
#include <stdarg.h>
#include <linux/fs.h>
#include <linux/hdreg.h>
#endif

#include <sys/stat.h>
#include <sys/time.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <paths.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#define MAXU16   0xffff     /* maximum unsigned 16-bit quantity */
#define BPN      4          /* bits per nibble */
#define NPB      2          /* nibbles per byte */

#define DOSMAGIC  0xaa55    /* DOS magic number */
#define MINBPS    512       /* minimum bytes per sector */
#define MAXSPC    128       /* maximum sectors per cluster */
#define MAXNFT    16        /* maximum number of FATs */
#define DEFBLK    4096      /* default block size */
#define DEFBLK16  2048      /* default block size FAT16 */
#define DEFRDE    512       /* default root directory entries */
#define RESFTE    2         /* reserved FAT entries */
#define MINCLS12  1         /* minimum FAT12 clusters */
#define MINCLS16  0x1000    /* minimum FAT16 clusters */
#define MINCLS32  2         /* minimum FAT32 clusters */
#define MAXCLS12  0xfed     /* maximum FAT12 clusters */
#define MAXCLS16  0xfff5    /* maximum FAT16 clusters */
#define MAXCLS32  0xffffff5 /* maximum FAT32 clusters */

#define mincls(fat)  ((fat) == 12 ? MINCLS12 :    \
                      (fat) == 16 ? MINCLS16 :    \
                                        MINCLS32)

#define maxcls(fat)  ((fat) == 12 ? MAXCLS12 :    \
                      (fat) == 16 ? MAXCLS16 :    \
                                        MAXCLS32)

#define mk1(p, x)                           \
    (p) = (u_int8_t)(x)

#define mk2(p, x)                           \
    (p)[0] = (u_int8_t)(x),                 \
    (p)[1] = (u_int8_t)((x) >> 010)

#define mk4(p, x)                           \
    (p)[0] = (u_int8_t)(x),                 \
    (p)[1] = (u_int8_t)((x) >> 010),        \
    (p)[2] = (u_int8_t)((x) >> 020),        \
    (p)[3] = (u_int8_t)((x) >> 030)

#define argto1(arg, lo, msg)  argtou(arg, lo, 0xff, msg)
#define argto2(arg, lo, msg)  argtou(arg, lo, 0xffff, msg)
#define argto4(arg, lo, msg)  argtou(arg, lo, 0xffffffff, msg)
#define argtox(arg, lo, msg)  argtou(arg, lo, UINT_MAX, msg)

struct bs {
    u_int8_t jmp[3];        /* bootstrap entry point */
    u_int8_t oem[8];        /* OEM name and version */
};

struct bsbpb {
    u_int8_t bps[2];    /* bytes per sector */
    u_int8_t spc;       /* sectors per cluster */
    u_int8_t res[2];    /* reserved sectors */
    u_int8_t nft;       /* number of FATs */
    u_int8_t rde[2];    /* root directory entries */
    u_int8_t sec[2];    /* total sectors */
    u_int8_t mid;       /* media descriptor */
    u_int8_t spf[2];    /* sectors per FAT */
    u_int8_t spt[2];    /* sectors per track */
    u_int8_t hds[2];    /* drive heads */
    u_int8_t hid[4];    /* hidden sectors */
    u_int8_t bsec[4];   /* big total sectors */
};

struct bsxbpb {
    u_int8_t bspf[4];       /* big sectors per FAT */
    u_int8_t xflg[2];       /* FAT control flags */
    u_int8_t vers[2];       /* file system version */
    u_int8_t rdcl[4];       /* root directory start cluster */
    u_int8_t infs[2];       /* file system info sector */
    u_int8_t bkbs[2];       /* backup boot sector */
    u_int8_t rsvd[12];      /* reserved */
};

struct bsx {
    u_int8_t drv;           /* drive number */
    u_int8_t rsvd;          /* reserved */
    u_int8_t sig;           /* extended boot signature */
    u_int8_t volid[4];      /* volume ID number */
    u_int8_t label[11];     /* volume label */
    u_int8_t type[8];       /* file system type */
};

struct de {
    u_int8_t namext[11];    /* name and extension */
    u_int8_t attr;          /* attributes */
    u_int8_t rsvd[10];      /* reserved */
    u_int8_t time[2];       /* creation time */
    u_int8_t date[2];       /* creation date */
    u_int8_t clus[2];       /* starting cluster */
    u_int8_t size[4];       /* size */
};

struct bpb {
    u_int bps;          /* bytes per sector */
    u_int spc;          /* sectors per cluster */
    u_int res;          /* reserved sectors */
    u_int nft;          /* number of FATs */
    u_int rde;          /* root directory entries */
    u_int sec;          /* total sectors */
    u_int mid;          /* media descriptor */
    u_int spf;          /* sectors per FAT */
    u_int spt;          /* sectors per track */
    u_int hds;          /* drive heads */
    u_int hid;          /* hidden sectors */
    u_int bsec;         /* big total sectors */
    u_int bspf;         /* big sectors per FAT */
    u_int rdcl;         /* root directory start cluster */
    u_int infs;         /* file system info sector */
    u_int bkbs;         /* backup boot sector */
};

#define BPBGAP 0, 0, 0, 0, 0, 0

static struct {
    const char *name;
    struct bpb bpb;
} const stdfmt[] = {
    {"160",  {512, 1, 1, 2,  64,  320, 0xfe, 1,  8, 1, BPBGAP}},
    {"180",  {512, 1, 1, 2,  64,  360, 0xfc, 2,  9, 1, BPBGAP}},
    {"320",  {512, 2, 1, 2, 112,  640, 0xff, 1,  8, 2, BPBGAP}},
    {"360",  {512, 2, 1, 2, 112,  720, 0xfd, 2,  9, 2, BPBGAP}},
    {"640",  {512, 2, 1, 2, 112, 1280, 0xfb, 2,  8, 2, BPBGAP}},
    {"720",  {512, 2, 1, 2, 112, 1440, 0xf9, 3,  9, 2, BPBGAP}},
    {"1200", {512, 1, 1, 2, 224, 2400, 0xf9, 7, 15, 2, BPBGAP}},
    {"1232", {1024,1, 1, 2, 192, 1232, 0xfe, 2,  8, 2, BPBGAP}},
    {"1440", {512, 1, 1, 2, 224, 2880, 0xf0, 9, 18, 2, BPBGAP}},
    {"2880", {512, 2, 1, 2, 240, 5760, 0xf0, 9, 36, 2, BPBGAP}}
};

static const u_int8_t bootcode[] = {
    0xfa,               /* cli             */
    0x31, 0xc0,         /* xor    ax,ax    */
    0x8e, 0xd0,         /* mov    ss,ax    */
    0xbc, 0x00, 0x7c,   /* mov    sp,7c00h */
    0xfb,               /* sti             */
    0x8e, 0xd8,         /* mov    ds,ax    */
    0xe8, 0x00, 0x00,   /* call   $ + 3    */
    0x5e,               /* pop    si       */
    0x83, 0xc6, 0x19,   /* add    si,+19h  */
    0xbb, 0x07, 0x00,   /* mov    bx,0007h */
    0xfc,               /* cld             */
    0xac,               /* lodsb           */
    0x84, 0xc0,         /* test   al,al    */
    0x74, 0x06,         /* jz     $ + 8    */
    0xb4, 0x0e,         /* mov    ah,0eh   */
    0xcd, 0x10,         /* int    10h      */
    0xeb, 0xf5,         /* jmp    $ - 9    */
    0x30, 0xe4,         /* xor    ah,ah    */
    0xcd, 0x16,         /* int    16h      */
    0xcd, 0x19,         /* int    19h      */
    0x0d, 0x0a,
    'N', 'o', 'n', '-', 's', 'y', 's', 't',
    'e', 'm', ' ', 'd', 'i', 's', 'k',
    0x0d, 0x0a,
    'P', 'r', 'e', 's', 's', ' ', 'a', 'n',
    'y', ' ', 'k', 'e', 'y', ' ', 't', 'o',
    ' ', 'r', 'e', 'b', 'o', 'o', 't',
    0x0d, 0x0a,
    0
};

static void check_mounted(const char *, mode_t);
static void getstdfmt(const char *, struct bpb *);
static void getdiskinfo(int, const char *, const char *, int, struct bpb *);
static void print_bpb(struct bpb *);
static u_int ckgeom(const char *, u_int, const char *);
static u_int argtou(const char *, u_int, u_int, const char *);
static off_t argtooff(const char *, const char *);
static int oklabel(const char *);
static void mklabel(u_int8_t *, const char *);
static void setstr(u_int8_t *, const char *, size_t);
static void usage(void);

/*
 * Construct a FAT12, FAT16, or FAT32 file system.
 */
int newfs_msdos_main(int argc, char *argv[])
{
    static const char opts[] = "@:NAB:C:F:I:L:O:S:a:b:c:e:f:h:i:k:m:n:o:r:s:u:";
    const char *opt_B = NULL, *opt_L = NULL, *opt_O = NULL, *opt_f = NULL;
    u_int opt_F = 0, opt_I = 0, opt_S = 0, opt_a = 0, opt_b = 0, opt_c = 0;
    u_int opt_e = 0, opt_h = 0, opt_i = 0, opt_k = 0, opt_m = 0, opt_n = 0;
    u_int opt_o = 0, opt_r = 0, opt_s = 0, opt_u = 0;
    u_int opt_A = 0;
    int opt_N = 0;
    int Iflag = 0, mflag = 0, oflag = 0;
    char buf[MAXPATHLEN];
    struct stat sb;
    struct timeval tv;
    struct bpb bpb;
    struct tm *tm;
    struct bs *bs;
    struct bsbpb *bsbpb;
    struct bsxbpb *bsxbpb;
    struct bsx *bsx;
    struct de *de;
    u_int8_t *img;
    const char *fname, *dtype, *bname;
    ssize_t n;
    time_t now;
    u_int fat, bss, rds, cls, dir, lsn, x, x1, x2;
    u_int extra_res, alignment=0, set_res, set_spf, set_spc, tempx, attempts=0;
    int ch, fd, fd1;
    off_t opt_create = 0, opt_ofs = 0;

    while ((ch = getopt(argc, argv, opts)) != -1)
        switch (ch) {
        case '@':
            opt_ofs = argtooff(optarg, "offset");
            break;
        case 'N':
            opt_N = 1;
            break;
        case 'A':
            opt_A = 1;
            break;
        case 'B':
            opt_B = optarg;
            break;
        case 'C':
            opt_create = argtooff(optarg, "create size");
            break;
        case 'F':
            if (strcmp(optarg, "12") &&  strcmp(optarg, "16") && strcmp(optarg, "32"))
                errx(1, "%s: bad FAT type", optarg);
            opt_F = atoi(optarg);
            break;
        case 'I':
            opt_I = argto4(optarg, 0, "volume ID");
            Iflag = 1;
            break;
        case 'L':
            if (!oklabel(optarg))
                errx(1, "%s: bad volume label", optarg);
            opt_L = optarg;
            break;
        case 'O':
            if (strlen(optarg) > 8)
                errx(1, "%s: bad OEM string", optarg);
            opt_O = optarg;
            break;
        case 'S':
            opt_S = argto2(optarg, 1, "bytes/sector");
            break;
        case 'a':
            opt_a = argto4(optarg, 1, "sectors/FAT");
            break;
        case 'b':
            opt_b = argtox(optarg, 1, "block size");
            opt_c = 0;
            break;
        case 'c':
            opt_c = argto1(optarg, 1, "sectors/cluster");
            opt_b = 0;
            break;
        case 'e':
            opt_e = argto2(optarg, 1, "directory entries");
            break;
        case 'f':
            opt_f = optarg;
            break;
        case 'h':
            opt_h = argto2(optarg, 1, "drive heads");
            break;
        case 'i':
            opt_i = argto2(optarg, 1, "info sector");
            break;
        case 'k':
            opt_k = argto2(optarg, 1, "backup sector");
            break;
        case 'm':
            opt_m = argto1(optarg, 0, "media descriptor");
            mflag = 1;
            break;
        case 'n':
            opt_n = argto1(optarg, 1, "number of FATs");
            break;
        case 'o':
            opt_o = argto4(optarg, 0, "hidden sectors");
            oflag = 1;
            break;
        case 'r':
            opt_r = argto2(optarg, 1, "reserved sectors");
            break;
        case 's':
            opt_s = argto4(optarg, 1, "file system size");
            break;
        case 'u':
            opt_u = argto2(optarg, 1, "sectors/track");
            break;
        default:
            usage();
        }
    argc -= optind;
    argv += optind;
    if (argc < 1 || argc > 2)
        usage();
    fname = *argv++;
    if (!opt_create && !strchr(fname, '/')) {
        snprintf(buf, sizeof(buf), "%s%s", _PATH_DEV, fname);
        if (!(fname = strdup(buf)))
            err(1, "%s", buf);
    }
    dtype = *argv;
    if (opt_A) {
        if (opt_r)
            errx(1, "align (-A) is incompatible with -r");
        if (opt_N)
            errx(1, "align (-A) is incompatible with -N");
    }
    if (opt_create) {
        if (opt_N)
            errx(1, "create (-C) is incompatible with -N");
        fd = open(fname, O_RDWR | O_CREAT | O_TRUNC, 0644);
        if (fd == -1)
            errx(1, "failed to create %s", fname);
        if (ftruncate(fd, opt_create))
            errx(1, "failed to initialize %jd bytes", (intmax_t)opt_create);
    } else if ((fd = open(fname, opt_N ? O_RDONLY : O_RDWR)) == -1)
        err(1, "%s", fname);
    if (fstat(fd, &sb))
        err(1, "%s", fname);
    if (opt_create) {
        if (!S_ISREG(sb.st_mode))
            warnx("warning, %s is not a regular file", fname);
    } else {
        if (!S_ISCHR(sb.st_mode))
            warnx("warning, %s is not a character device", fname);
    }
    if (!opt_N)
        check_mounted(fname, sb.st_mode);
    if (opt_ofs && opt_ofs != lseek(fd, opt_ofs, SEEK_SET))
        errx(1, "cannot seek to %jd", (intmax_t)opt_ofs);
    memset(&bpb, 0, sizeof(bpb));
    if (opt_f) {
        getstdfmt(opt_f, &bpb);
        bpb.bsec = bpb.sec;
        bpb.sec = 0;
        bpb.bspf = bpb.spf;
        bpb.spf = 0;
    }
    if (opt_h)
        bpb.hds = opt_h;
    if (opt_u)
        bpb.spt = opt_u;
    if (opt_S)
        bpb.bps = opt_S;
    if (opt_s)
        bpb.bsec = opt_s;
    if (oflag)
        bpb.hid = opt_o;
    if (!(opt_f || (opt_h && opt_u && opt_S && opt_s && oflag))) {
        off_t delta;
        getdiskinfo(fd, fname, dtype, oflag, &bpb);
        if (opt_s) {
            bpb.bsec = opt_s;
        }
        bpb.bsec -= (opt_ofs / bpb.bps);
        delta = bpb.bsec % bpb.spt;
        if (delta != 0) {
            warnx("trim %d sectors from %d to adjust to a multiple of %d",
                  (int)delta, bpb.bsec, bpb.spt);
            bpb.bsec -= delta;
        }
        if (bpb.spc == 0) {    /* set defaults */
            if (bpb.bsec <= 6000)    /* about 3MB -> 512 bytes */
                bpb.spc = 1;
            else if (bpb.bsec <= (1<<17)) /* 64M -> 4k */
                bpb.spc = 8;
            else if (bpb.bsec <= (1<<19)) /* 256M -> 8k */
                bpb.spc = 16;
            else if (bpb.bsec <= (1<<22)) /* 2G -> 16k, some versions of windows
                                         require a minimum of 65527 clusters */
                bpb.spc = 32;
            else
                bpb.spc = 64;        /* otherwise 32k */
        }
    }
    if (!powerof2(bpb.bps))
        errx(1, "bytes/sector (%u) is not a power of 2", bpb.bps);
    if (bpb.bps < MINBPS)
        errx(1, "bytes/sector (%u) is too small; minimum is %u",
             bpb.bps, MINBPS);
    if (!(fat = opt_F)) {
        if (opt_f)
            fat = 12;
        else if (!opt_e && (opt_i || opt_k))
            fat = 32;
    }
    if ((fat == 32 && opt_e) || (fat != 32 && (opt_i || opt_k)))
        errx(1, "-%c is not a legal FAT%s option",
             fat == 32 ? 'e' : opt_i ? 'i' : 'k',
                     fat == 32 ? "32" : "12/16");
    if (opt_f && fat == 32)
        bpb.rde = 0;
    if (opt_b) {
        if (!powerof2(opt_b))
            errx(1, "block size (%u) is not a power of 2", opt_b);
        if (opt_b < bpb.bps)
            errx(1, "block size (%u) is too small; minimum is %u",
                 opt_b, bpb.bps);
        if (opt_b > bpb.bps * MAXSPC)
            errx(1, "block size (%u) is too large; maximum is %u", opt_b, bpb.bps * MAXSPC);
        bpb.spc = opt_b / bpb.bps;
    }
    if (opt_c) {
        if (!powerof2(opt_c))
            errx(1, "sectors/cluster (%u) is not a power of 2", opt_c);
        bpb.spc = opt_c;
    }
    if (opt_r)
        bpb.res = opt_r;
    if (opt_n) {
        if (opt_n > MAXNFT)
            errx(1, "number of FATs (%u) is too large; maximum is %u", opt_n, MAXNFT);
        bpb.nft = opt_n;
    }
    if (opt_e)
        bpb.rde = opt_e;
    if (mflag) {
        if (opt_m < 0xf0)
            errx(1, "illegal media descriptor (%#x)", opt_m);
        bpb.mid = opt_m;
    }
    if (opt_a)
        bpb.bspf = opt_a;
    if (opt_i)
        bpb.infs = opt_i;
    if (opt_k)
        bpb.bkbs = opt_k;
    bss = 1;
    bname = NULL;
    fd1 = -1;
    if (opt_B) {
        bname = opt_B;
        if (!strchr(bname, '/')) {
            snprintf(buf, sizeof(buf), "/boot/%s", bname);
            if (!(bname = strdup(buf)))
                err(1, "%s", buf);
        }
        if ((fd1 = open(bname, O_RDONLY)) == -1 || fstat(fd1, &sb))
            err(1, "%s", bname);
        if (!S_ISREG(sb.st_mode) || sb.st_size % bpb.bps ||
                sb.st_size < bpb.bps || sb.st_size > bpb.bps * MAXU16)
            errx(1, "%s: inappropriate file type or format", bname);
        bss = sb.st_size / bpb.bps;
    }
    if (!bpb.nft)
        bpb.nft = 2;
    if (!fat) {
        if (bpb.bsec < (bpb.res ? bpb.res : bss) +
                howmany((RESFTE + (bpb.spc ? MINCLS16 : MAXCLS12 + 1)) *
                        ((bpb.spc ? 16 : 12) / BPN), bpb.bps * NPB) *
                        bpb.nft +
                        howmany(bpb.rde ? bpb.rde : DEFRDE,
                                bpb.bps / sizeof(struct de)) +
                                (bpb.spc ? MINCLS16 : MAXCLS12 + 1) *
                                (bpb.spc ? bpb.spc : howmany(DEFBLK, bpb.bps)))
            fat = 12;
        else if (bpb.rde || bpb.bsec <
                (bpb.res ? bpb.res : bss) +
                howmany((RESFTE + MAXCLS16) * 2, bpb.bps) * bpb.nft +
                howmany(DEFRDE, bpb.bps / sizeof(struct de)) +
                (MAXCLS16 + 1) *
                (bpb.spc ? bpb.spc : howmany(8192, bpb.bps)))
            fat = 16;
        else
            fat = 32;
    }
    x = bss;
    if (fat == 32) {
        if (!bpb.infs) {
            if (x == MAXU16 || x == bpb.bkbs)
                errx(1, "no room for info sector");
            bpb.infs = x;
        }
        if (bpb.infs != MAXU16 && x <= bpb.infs)
            x = bpb.infs + 1;
        if (!bpb.bkbs) {
            if (x == MAXU16)
                errx(1, "no room for backup sector");
            bpb.bkbs = x;
        } else if (bpb.bkbs != MAXU16 && bpb.bkbs == bpb.infs)
            errx(1, "backup sector would overwrite info sector");
        if (bpb.bkbs != MAXU16 && x <= bpb.bkbs)
            x = bpb.bkbs + 1;
    }

    extra_res = 0;
    set_res = !bpb.res;
    set_spf = !bpb.bspf;
    set_spc = !bpb.spc;
    tempx = x;
    /*
     * Attempt to align if opt_A is set. This is done by increasing the number
     * of reserved blocks. This can cause other factors to change, which can in
     * turn change the alignment. This should take at most 2 iterations, as
     * increasing the reserved amount may cause the FAT size to decrease by 1,
     * requiring another nft reserved blocks. If spc changes, it will
     * be half of its previous size, and thus will not throw off alignment.
     */
    do {
        x = tempx;
        if (set_res)
            bpb.res = (fat == 32 ? MAX(x, MAX(16384 / bpb.bps, 4)) : x) + extra_res;
        else if (bpb.res < x)
            errx(1, "too few reserved sectors");
        if (fat != 32 && !bpb.rde)
            bpb.rde = DEFRDE;
        rds = howmany(bpb.rde, bpb.bps / sizeof(struct de));
        if (set_spc)
            for (bpb.spc = howmany(fat == 16 ? DEFBLK16 : DEFBLK, bpb.bps);
                    bpb.spc < MAXSPC &&
                    bpb.res +
                    howmany((RESFTE + maxcls(fat)) * (fat / BPN),
                            bpb.bps * NPB) * bpb.nft +
                            rds +
                            (u_int64_t)(maxcls(fat) + 1) * bpb.spc <= bpb.bsec;
                    bpb.spc <<= 1);
        if (fat != 32 && bpb.bspf > MAXU16)
            errx(1, "too many sectors/FAT for FAT12/16");
        x1 = bpb.res + rds;
        x = bpb.bspf ? bpb.bspf : 1;
        if (x1 + (u_int64_t)x * bpb.nft > bpb.bsec)
            errx(1, "meta data exceeds file system size");
        x1 += x * bpb.nft;
        x = (u_int64_t)(bpb.bsec - x1) * bpb.bps * NPB /
                (bpb.spc * bpb.bps * NPB + fat / BPN * bpb.nft);
        x2 = howmany((RESFTE + MIN(x, maxcls(fat))) * (fat / BPN), bpb.bps * NPB);
        if (set_spf) {
            if (!bpb.bspf) {
                bpb.bspf = x2;
            }
            x1 += (bpb.bspf - 1) * bpb.nft;
        }
        if(set_res) {
            /* attempt to align root directory */
            alignment = (bpb.res + bpb.bspf * bpb.nft) % bpb.spc;
            extra_res += bpb.spc - alignment;
        }
        attempts++;
    } while(opt_A && alignment != 0 && attempts < 2);
    if (alignment != 0)
        warnx("warning: Alignment failed.");

    cls = (bpb.bsec - x1) / bpb.spc;
    x = (u_int64_t)bpb.bspf * bpb.bps * NPB / (fat / BPN) - RESFTE;
    if (cls > x)
        cls = x;
    if (bpb.bspf < x2)
        warnx("warning: sectors/FAT limits file system to %u clusters", cls);
    if (cls < mincls(fat))
        errx(1, "%u clusters too few clusters for FAT%u, need %u", cls, fat, mincls(fat));
    if (cls > maxcls(fat)) {
        cls = maxcls(fat);
        bpb.bsec = x1 + (cls + 1) * bpb.spc - 1;
        warnx("warning: FAT type limits file system to %u sectors", bpb.bsec);
    }
    printf("%s: %u sector%s in %u FAT%u cluster%s (%u bytes/cluster)\n",
           fname, cls * bpb.spc, cls * bpb.spc == 1 ? "" : "s", cls, fat,
           cls == 1 ? "" : "s", bpb.bps * bpb.spc);
    if (!bpb.mid)
        bpb.mid = !bpb.hid ? 0xf0 : 0xf8;
    if (fat == 32)
        bpb.rdcl = RESFTE;
    if (bpb.hid + bpb.bsec <= MAXU16) {
        bpb.sec = bpb.bsec;
        bpb.bsec = 0;
    }
    if (fat != 32) {
        bpb.spf = bpb.bspf;
        bpb.bspf = 0;
    }
    print_bpb(&bpb);
    if (!opt_N) {
        gettimeofday(&tv, NULL);
        now = tv.tv_sec;
        tm = localtime(&now);
        if (!(img = malloc(bpb.bps)))
            err(1, "%u", bpb.bps);
        dir = bpb.res + (bpb.spf ? bpb.spf : bpb.bspf) * bpb.nft;
        for (lsn = 0; lsn < dir + (fat == 32 ? bpb.spc : rds); lsn++) {
            x = lsn;
            if (opt_B && fat == 32 && bpb.bkbs != MAXU16 && bss <= bpb.bkbs && x >= bpb.bkbs) {
                x -= bpb.bkbs;
                if (!x && lseek(fd1, opt_ofs, SEEK_SET))
                    err(1, "%s", bname);
            }
            if (opt_B && x < bss) {
                if ((n = read(fd1, img, bpb.bps)) == -1)
                    err(1, "%s", bname);
                if ((unsigned)n != bpb.bps)
                    errx(1, "%s: can't read sector %u", bname, x);
            } else
                memset(img, 0, bpb.bps);
            if (!lsn || (fat == 32 && bpb.bkbs != MAXU16 && lsn == bpb.bkbs)) {
                x1 = sizeof(struct bs);
                bsbpb = (struct bsbpb *)(img + x1);
                mk2(bsbpb->bps, bpb.bps);
                mk1(bsbpb->spc, bpb.spc);
                mk2(bsbpb->res, bpb.res);
                mk1(bsbpb->nft, bpb.nft);
                mk2(bsbpb->rde, bpb.rde);
                mk2(bsbpb->sec, bpb.sec);
                mk1(bsbpb->mid, bpb.mid);
                mk2(bsbpb->spf, bpb.spf);
                mk2(bsbpb->spt, bpb.spt);
                mk2(bsbpb->hds, bpb.hds);
                mk4(bsbpb->hid, bpb.hid);
                mk4(bsbpb->bsec, bpb.bsec);
                x1 += sizeof(struct bsbpb);
                if (fat == 32) {
                    bsxbpb = (struct bsxbpb *)(img + x1);
                    mk4(bsxbpb->bspf, bpb.bspf);
                    mk2(bsxbpb->xflg, 0);
                    mk2(bsxbpb->vers, 0);
                    mk4(bsxbpb->rdcl, bpb.rdcl);
                    mk2(bsxbpb->infs, bpb.infs);
                    mk2(bsxbpb->bkbs, bpb.bkbs);
                    x1 += sizeof(struct bsxbpb);
                }
                bsx = (struct bsx *)(img + x1);
                mk1(bsx->sig, 0x29);
                if (Iflag)
                    x = opt_I;
                else
                    x = (((u_int)(1 + tm->tm_mon) << 8 |
                            (u_int)tm->tm_mday) +
                            ((u_int)tm->tm_sec << 8 |
                                    (u_int)(tv.tv_usec / 10))) << 16 |
                                    ((u_int)(1900 + tm->tm_year) +
                                            ((u_int)tm->tm_hour << 8 |
                                                    (u_int)tm->tm_min));
                mk4(bsx->volid, x);
                mklabel(bsx->label, opt_L ? opt_L : "NO NAME");
                sprintf(buf, "FAT%u", fat);
                setstr(bsx->type, buf, sizeof(bsx->type));
                if (!opt_B) {
                    x1 += sizeof(struct bsx);
                    bs = (struct bs *)img;
                    mk1(bs->jmp[0], 0xeb);
                    mk1(bs->jmp[1], x1 - 2);
                    mk1(bs->jmp[2], 0x90);
                    setstr(bs->oem, opt_O ? opt_O : "BSD  4.4",
                            sizeof(bs->oem));
                    memcpy(img + x1, bootcode, sizeof(bootcode));
                    mk2(img + MINBPS - 2, DOSMAGIC);
                }
            } else if (fat == 32 && bpb.infs != MAXU16 &&
                    (lsn == bpb.infs || (bpb.bkbs != MAXU16 &&
                                    lsn == bpb.bkbs + bpb.infs))) {
                mk4(img, 0x41615252);
                mk4(img + MINBPS - 28, 0x61417272);
                mk4(img + MINBPS - 24, 0xffffffff);
                mk4(img + MINBPS - 20, bpb.rdcl);
                mk2(img + MINBPS - 2, DOSMAGIC);
            } else if (lsn >= bpb.res && lsn < dir &&
                    !((lsn - bpb.res) % (bpb.spf ? bpb.spf : bpb.bspf))) {
                mk1(img[0], bpb.mid);
                for (x = 1; x < fat * (fat == 32 ? 3 : 2) / 8; x++)
                    mk1(img[x], fat == 32 && x % 4 == 3 ? 0x0f : 0xff);
            } else if (lsn == dir && opt_L) {
                de = (struct de *)img;
                mklabel(de->namext, opt_L);
                mk1(de->attr, 050);
                x = (u_int)tm->tm_hour << 11 |
                        (u_int)tm->tm_min << 5 |
                        (u_int)tm->tm_sec >> 1;
                mk2(de->time, x);
                x = (u_int)(tm->tm_year - 80) << 9 |
                        (u_int)(tm->tm_mon + 1) << 5 |
                        (u_int)tm->tm_mday;
                mk2(de->date, x);
            }
            if ((n = write(fd, img, bpb.bps)) == -1)
                err(1, "%s", fname);
            if ((unsigned)n != bpb.bps) {
                errx(1, "%s: can't write sector %u", fname, lsn);
                exit(1);
            }
        }
    }
    return 0;
}

/*
 * Exit with error if file system is mounted.
 */
static void check_mounted(const char *fname, mode_t mode)
{
#ifdef ANDROID
    warnx("Skipping mount checks");
#else
    struct statfs *mp;
    const char *s1, *s2;
    size_t len;
    int n, r;

    if (!(n = getmntinfo(&mp, MNT_NOWAIT)))
        err(1, "getmntinfo");
    len = strlen(_PATH_DEV);
    s1 = fname;
    if (!strncmp(s1, _PATH_DEV, len))
        s1 += len;
    r = S_ISCHR(mode) && s1 != fname && *s1 == 'r';
    for (; n--; mp++) {
        s2 = mp->f_mntfromname;
        if (!strncmp(s2, _PATH_DEV, len))
            s2 += len;
        if ((r && s2 != mp->f_mntfromname && !strcmp(s1 + 1, s2)) || !strcmp(s1, s2))
            errx(1, "%s is mounted on %s", fname, mp->f_mntonname);
    }
#endif
}

/*
 * Get a standard format.
 */
static void getstdfmt(const char *fmt, struct bpb *bpb)
{
    u_int x, i;

    x = sizeof(stdfmt) / sizeof(stdfmt[0]);
    for (i = 0; i < x && strcmp(fmt, stdfmt[i].name); i++);
    if (i == x)
        errx(1, "%s: unknown standard format", fmt);
    *bpb = stdfmt[i].bpb;
}

/*
 * Get disk slice, partition, and geometry information.
 */

#ifdef ANDROID
static void getdiskinfo(int fd, const char *fname, const char *dtype,
                        __unused int oflag,struct bpb *bpb)
{
    struct hd_geometry geom;
    u_long block_size;

    if (ioctl(fd, BLKSSZGET, &bpb->bps)) {
        fprintf(stderr, "Error getting bytes / sector (%s)\n", strerror(errno));
        exit(1);
    }

    ckgeom(fname, bpb->bps, "bytes/sector");

    if (ioctl(fd, BLKGETSIZE, &block_size)) {
        fprintf(stderr, "Error getting blocksize (%s)\n", strerror(errno));
        exit(1);
    }

    if (block_size > UINT32_MAX) {
        fprintf(stderr, "Error blocksize too large: %lu\n", block_size);
        exit(1);
    }

    bpb->bsec = (u_int)block_size;

    if (ioctl(fd, HDIO_GETGEO, &geom)) {
        fprintf(stderr, "Error getting gemoetry (%s) - trying sane values\n", strerror(errno));
        geom.heads = 64;
        geom.sectors = 63;
    }

    if (!geom.heads) {
        printf("Bogus heads from kernel - setting sane value\n");
        geom.heads = 64;
    }

    if (!geom.sectors) {
        printf("Bogus sectors from kernel - setting sane value\n");
        geom.sectors = 63;
    }

    bpb->spt = geom.sectors;
    ckgeom(fname, bpb->spt, "sectors/track");

    bpb->hds = geom.heads;
    ckgeom(fname, bpb->hds, "drive heads");
}

#else

static void getdiskinfo(int fd, const char *fname, const char *dtype,
                        __unused int oflag, struct bpb *bpb)
{
    struct disklabel *lp, dlp;
    struct fd_type type;
    off_t ms, hs = 0;

    lp = NULL;

    /* If the user specified a disk type, try to use that */
    if (dtype != NULL) {
        lp = getdiskbyname(dtype);
    }

    /* Maybe it's a floppy drive */
    if (lp == NULL) {
        if (ioctl(fd, DIOCGMEDIASIZE, &ms) == -1) {
            struct stat st;

            if (fstat(fd, &st))
                err(1, "Cannot get disk size");
            /* create a fake geometry for a file image */
            ms = st.st_size;
            dlp.d_secsize = 512;
            dlp.d_nsectors = 63;
            dlp.d_ntracks = 255;
            dlp.d_secperunit = ms / dlp.d_secsize;
            lp = &dlp;
        } else if (ioctl(fd, FD_GTYPE, &type) != -1) {
            dlp.d_secsize = 128 << type.secsize;
            dlp.d_nsectors = type.sectrac;
            dlp.d_ntracks = type.heads;
            dlp.d_secperunit = ms / dlp.d_secsize;
            lp = &dlp;
        }
    }

    /* Maybe it's a fixed drive */
    if (lp == NULL) {
        if (ioctl(fd, DIOCGDINFO, &dlp) == -1) {
            if (bpb->bps == 0 && ioctl(fd, DIOCGSECTORSIZE, &dlp.d_secsize) == -1)
                errx(1, "Cannot get sector size, %s", strerror(errno));

            /* XXX Should we use bpb->bps if it's set? */
            dlp.d_secperunit = ms / dlp.d_secsize;

            if (bpb->spt == 0 && ioctl(fd, DIOCGFWSECTORS, &dlp.d_nsectors) == -1) {
                warnx("Cannot get number of sectors per track, %s", strerror(errno));
                dlp.d_nsectors = 63;
            }
            if (bpb->hds == 0 && ioctl(fd, DIOCGFWHEADS, &dlp.d_ntracks) == -1) {
                warnx("Cannot get number of heads, %s", strerror(errno));
                if (dlp.d_secperunit <= 63*1*1024)
                    dlp.d_ntracks = 1;
                else if (dlp.d_secperunit <= 63*16*1024)
                    dlp.d_ntracks = 16;
                else
                    dlp.d_ntracks = 255;
            }
        }

        hs = (ms / dlp.d_secsize) - dlp.d_secperunit;
        lp = &dlp;
    }

    if (bpb->bps == 0)
        bpb->bps = ckgeom(fname, lp->d_secsize, "bytes/sector");
    if (bpb->spt == 0)
        bpb->spt = ckgeom(fname, lp->d_nsectors, "sectors/track");
    if (bpb->hds == 0)
        bpb->hds = ckgeom(fname, lp->d_ntracks, "drive heads");
    if (bpb->bsec == 0)
        bpb->bsec = lp->d_secperunit;
    if (bpb->hid == 0)
        bpb->hid = hs;
}
#endif

/*
 * Print out BPB values.
 */
static void print_bpb(struct bpb *bpb)
{
    printf("bps=%u spc=%u res=%u nft=%u", bpb->bps, bpb->spc, bpb->res,
           bpb->nft);
    if (bpb->rde)
        printf(" rde=%u", bpb->rde);
    if (bpb->sec)
        printf(" sec=%u", bpb->sec);
    printf(" mid=%#x", bpb->mid);
    if (bpb->spf)
        printf(" spf=%u", bpb->spf);
    printf(" spt=%u hds=%u hid=%u", bpb->spt, bpb->hds, bpb->hid);
    if (bpb->bsec)
        printf(" bsec=%u", bpb->bsec);
    if (!bpb->spf) {
        printf(" bspf=%u rdcl=%u", bpb->bspf, bpb->rdcl);
        printf(" infs=");
        printf(bpb->infs == MAXU16 ? "%#x" : "%u", bpb->infs);
        printf(" bkbs=");
        printf(bpb->bkbs == MAXU16 ? "%#x" : "%u", bpb->bkbs);
    }
    printf("\n");
}

/*
 * Check a disk geometry value.
 */
static u_int ckgeom(const char *fname, u_int val, const char *msg)
{
    if (!val)
        errx(1, "%s: no default %s", fname, msg);
    if (val > MAXU16)
        errx(1, "%s: illegal %s %d", fname, msg, val);
    return val;
}

/*
 * Convert and check a numeric option argument.
 */
static u_int argtou(const char *arg, u_int lo, u_int hi, const char *msg)
{
    char *s;
    u_long x;

    errno = 0;
    x = strtoul(arg, &s, 0);
    if (errno || !*arg || *s || x < lo || x > hi)
        errx(1, "%s: bad %s", arg, msg);
    return x;
}

/*
 * Same for off_t, with optional skmgpP suffix
 */
static off_t argtooff(const char *arg, const char *msg)
{
    char *s;
    off_t x;

    x = strtoll(arg, &s, 0);
    /* allow at most one extra char */
    if (errno || x < 0 || (s[0] && s[1]) )
        errx(1, "%s: bad %s", arg, msg);
    if (*s) {    /* the extra char is the multiplier */
        switch (*s) {
            default:
                errx(1, "%s: bad %s", arg, msg);
                /* notreached */

            case 's':       /* sector */
            case 'S':
                x <<= 9;    /* times 512 */
                break;

            case 'k':       /* kilobyte */
            case 'K':
                x <<= 10;   /* times 1024 */
                break;

            case 'm':       /* megabyte */
            case 'M':
                x <<= 20;   /* times 1024*1024 */
                break;

            case 'g':       /* gigabyte */
            case 'G':
                x <<= 30;   /* times 1024*1024*1024 */
                break;

            case 'p':       /* partition start */
            case 'P':       /* partition start */
            case 'l':       /* partition length */
            case 'L':       /* partition length */
                errx(1, "%s: not supported yet %s", arg, msg);
                /* notreached */
        }
    }
    return x;
}

/*
 * Check a volume label.
 */
static int oklabel(const char *src)
{
    int c, i;

    for (i = 0; i <= 11; i++) {
        c = (u_char)*src++;
        if (c < ' ' + !i || strchr("\"*+,./:;<=>?[\\]|", c))
            break;
    }
    return i && !c;
}

/*
 * Make a volume label.
 */
static void mklabel(u_int8_t *dest, const char *src)
{
    int c, i;

    for (i = 0; i < 11; i++) {
        c = *src ? toupper(*src++) : ' ';
        *dest++ = !i && c == '\xe5' ? 5 : c;
    }
}

/*
 * Copy string, padding with spaces.
 */
static void setstr(u_int8_t *dest, const char *src, size_t len)
{
    while (len--)
        *dest++ = *src ? *src++ : ' ';
}

/*
 * Print usage message.
 */
static void usage(void)
{
    fprintf(stderr,
            "usage: newfs_msdos [ -options ] special [disktype]\n"
            "where the options are:\n"
            "\t-@ create file system at specified offset\n"
            "\t-A Attempt to cluster align root directory\n"
            "\t-B get bootstrap from file\n"
            "\t-C create image file with specified size\n"
            "\t-F FAT type (12, 16, or 32)\n"
            "\t-I volume ID\n"
            "\t-L volume label\n"
            "\t-N don't create file system: just print out parameters\n"
            "\t-O OEM string\n"
            "\t-S bytes/sector\n"
            "\t-a sectors/FAT\n"
            "\t-b block size\n"
            "\t-c sectors/cluster\n"
            "\t-e root directory entries\n"
            "\t-f standard format\n"
            "\t-h drive heads\n"
            "\t-i file system info sector\n"
            "\t-k backup boot sector\n"
            "\t-m media descriptor\n"
            "\t-n number of FATs\n"
            "\t-o hidden sectors\n"
            "\t-r reserved sectors\n"
            "\t-s file system size (sectors)\n"
            "\t-u sectors/track\n");
    exit(1);
}