/*      $OpenBSD: newfs_msdos.c,v 1.30 2025/09/17 16:07:57 deraadt Exp $        */

/*
 * 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.
 */

#include <sys/param.h>  /* powerof2 */
#include <sys/stat.h>
#include <sys/disklabel.h>
#include <sys/ioctl.h>
#include <sys/dkio.h>
#include <sys/mount.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <paths.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>
#include <util.h>

#define MINIMUM(a, b)   (((a) < (b)) ? (a) : (b))
#define MAXIMUM(a, b)   (((a) > (b)) ? (a) : (b))

#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  0xff5         /* minimum FAT16 clusters */
#define MINCLS32  0xfff5        /* minimum FAT32 clusters */
#define MAXCLS12  0xff4         /* maximum FAT12 clusters */
#define MAXCLS16  0xfff4        /* maximum FAT16 clusters */
#define MAXCLS32  0xffffff4     /* 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 */
};

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

static 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 int oklabel(const char *);
static void mklabel(u_int8_t *, const char *);
static void setstr(u_int8_t *, const char *, size_t);
static __dead void usage(void);

/*
 * Construct a FAT12, FAT16, or FAT32 file system.
 */
int
main(int argc, char *argv[])
{
    static char opts[] = "NB:F:I:L:O:S:a:b:c:e:f:h:i:k:m:n:o:qr:s:t:u:";
    static const char *opt_B, *opt_L, *opt_O, *opt_f;
    static u_int opt_F, opt_I, opt_S, opt_a, opt_b, opt_c, opt_e;
    static u_int opt_h, opt_i, opt_k, opt_m, opt_n, opt_o, opt_r;
    static u_int opt_s, opt_u;
    static int opt_N;
    static int Iflag, mflag, oflag;
    char buf[PATH_MAX];
    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 *dtype, *bname;
    char *sname, *fname;
    ssize_t n;
    time_t now;
    u_int fat, bss, rds, cls, dir, lsn, x, x1, x2;
    int ch, fd, fd1;

    if (pledge("stdio rpath wpath disklabel", NULL) == -1)
        err(1, "pledge");

    while ((ch = getopt(argc, argv, opts)) != -1)
        switch (ch) {
        case 'N':
            opt_N = 1;
            break;
        case 'B':
            opt_B = optarg;
            break;
        case 'F':
            opt_F = strtonum(optarg, 1, INT_MAX, NULL);
            if (!(opt_F == 12 || opt_F == 16 || opt_F == 32))
                errx(1, "%s: bad FAT type", 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 'q':                       /* Compat with newfs -q */
            break;
        case 'r':
            opt_r = argto2(optarg, 1, "reserved sectors");
            break;
        case 's':
            opt_s = argto4(optarg, 1, "file system size");
            break;
        case 't':                       /* Compat with newfs -t */
            break;
        case 'u':
            opt_u = argto2(optarg, 1, "sectors/track");
            break;
        default:
            usage();
        }
    argc -= optind;
    argv += optind;
    if (argc < 1 || argc > 2)
        usage();
    sname = *argv++;
    dtype = *argv;
    if ((fd = opendev(sname, opt_N ? O_RDONLY : O_RDWR, 0, &fname)) == -1 ||
        fstat(fd, &sb))
        err(1, "%s", fname);
    if (!opt_N)
        check_mounted(fname, sb.st_mode);
    if (S_ISBLK(sb.st_mode))
        errx(1, "%s: block device", fname);
    if (!S_ISCHR(sb.st_mode))
        warnx("warning: %s is not a character device", fname);
    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)))
        getdiskinfo(fd, fname, dtype, oflag, &bpb);
    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, NULL);
        }
        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;
    }
    if (!bpb.res)
        bpb.res = fat == 32 ? MAXIMUM(x, MAXIMUM(16384 / bpb.bps, 4)) : x;
    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 (!bpb.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 + MINIMUM(x, maxcls(fat))) * (fat / BPN),
                 bpb.bps * NPB);
    if (!bpb.bspf) {
        bpb.bspf = x2;
        x1 += (bpb.bspf - 1) * bpb.nft;
    }
    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;
        if ((tm = localtime(&now)) == NULL)
                errx(1, "Invalid time");

        if (!(img = malloc(bpb.bps)))
            err(1, NULL);
        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, 0, SEEK_SET))
                    err(1, "%s", bname);
            }
            if (opt_B && x < bss) {
                if ((n = read(fd1, img, bpb.bps)) == -1)
                    err(1, "%s", bname);
                if (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");
                snprintf(buf, sizeof 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, 0xffffffff);
                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 (n != bpb.bps)
                errx(1, "%s: can't write sector %u", fname, lsn);
        }
    }
    return 0;
}

/*
 * Exit with error if file system is mounted.
 */
static void
check_mounted(const char *fname, mode_t mode)
{
    struct statfs *mp;
    const char *s1, *s2;
    size_t len;
    int n, r;

    if (!(n = getmntinfo(&mp, MNT_NOWAIT)))
        err(1, "getmntinfo");
    len = sizeof(_PATH_DEV) - 1;
    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);
    }
}

/*
 * 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.
 */
static void
getdiskinfo(int fd, const char *fname, const char *dtype, int oflag,
            struct bpb *bpb)
{
    struct disklabel dl, *lp;
    const char *s1, *s2;
    int part, i;

    part = -1;
    s1 = fname;
    if ((s2 = strrchr(s1, '/')))
        s1 = s2 + 1;
    for (s2 = s1; *s2 && !isdigit((unsigned char)*s2); s2++);
    if (!*s2 || s2 == s1)
        s2 = NULL;
    else
        while (isdigit((unsigned char)*++s2));
    s1 = s2;
    if (s2)
        part = DL_PARTNAME2NUM(*s2++);
    if (!s2 || (*s2 && *s2 != '.'))
        errx(1, "%s: can't figure out partition info", fname);
    if ((((!oflag && part != -1) || !bpb->bsec)) ||
        !bpb->bps || !bpb->spt || !bpb->hds) {
        lp = &dl;
        i = ioctl(fd, DIOCGDINFO, lp);
        if (i == -1) {
            if (!dtype) {
                warn("ioctl (GDINFO)");
                errx(1, "%s: can't read disk label; "
                     "disk type must be specified", fname);
            } else if (!(lp = getdiskbyname(dtype)))
                errx(1, "%s: unknown disk type", dtype);
        }
        if (part == -1)
            part = RAW_PART;
        if (part >= lp->d_npartitions ||
            !DL_GETPSIZE(&lp->d_partitions[part]))
            errx(1, "%s: partition is unavailable", fname);
        if (!oflag && part != -1)
            bpb->hid += DL_GETPOFFSET(&lp->d_partitions[part]);
        if (!bpb->bsec)
            bpb->bsec = DL_GETPSIZE(&lp->d_partitions[part]);
        if (!bpb->bps)
            bpb->bps = ckgeom(fname, lp->d_secsize, "bytes/sector");
        if (!bpb->spt)
            bpb->spt = ckgeom(fname, lp->d_nsectors, "sectors/track");
        if (!bpb->hds)
            bpb->hds = ckgeom(fname, lp->d_ntracks, "drive heads");
        if (bpb->spt > 63) {
            bpb->hds = bpb->hds * bpb->spt / 63;
            bpb->spt = 63;
        }
    }
}

/*
 * 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", fname, msg);
    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;
}

/*
 * Check a volume label.
 */
static int
oklabel(const char *src)
{
    int c = 0, 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((unsigned char)*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 __dead void
usage(void)
{
        extern const char       *__progname;

        fprintf(stderr, "usage: %s "
            "[-N] [-a FAT-size] [-B boot] [-b block-size]\n"
            "\t[-c cluster-size] [-e dirents] [-F FAT-type] [-f format]\n"
            "\t[-h heads] [-I volid] [-i info] [-k backup] [-L label]\n"
            "\t[-m media] [-n FATs] [-O OEM] [-o hidden] [-r reserved]\n"
            "\t[-S sector-size] [-s total] [-u track-size] special\n"
            "\t[disktype]\n",
            __progname);
        exit(1);
}