xref: /freebsd/usr.sbin/boot0cfg/boot0cfg.c (revision c5dc421f98a544921dca4fdbaeae20d0a0f50093)

/*
 * Copyright (c) 1999 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 AND CONTRIBUTORS``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 OR CONTRIBUTORS
 * 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[] =
  "$FreeBSD$";
#endif /* not lint */

#include <sys/param.h>
#include <sys/disklabel.h>
#include <sys/stat.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>

#define MBRSIZE         512     /* master boot record size */

#define OFF_VERSION	0x1b0	/* offset: version number */
#define OFF_DRIVE	0x1ba	/* offset: setdrv drive */
#define OFF_FLAGS       0x1bb   /* offset: option flags */
#define OFF_TICKS       0x1bc   /* offset: clock ticks */
#define OFF_PTBL        0x1be   /* offset: partition table */
#define OFF_MAGIC       0x1fe   /* offset: magic number */

#define cv2(p)  ((p)[0] | (p)[1] << 010)

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

static const struct {
    const char *tok;
    int def;
} opttbl[] = {
    {"packet", 0},
    {"update", 1},
    {"setdrv", 0}
};
static const int nopt = sizeof(opttbl) / sizeof(opttbl[0]);

static const char fmt0[] = "#   flag     start chs   type"
    "       end chs       offset         size\n";

static const char fmt1[] = "%d   0x%02x   %4u:%3u:%2u   0x%02x"
    "   %4u:%3u:%2u   %10u   %10u\n";

static int read_mbr(const char *, u_int8_t **, int);
static void write_mbr(const char *, int, u_int8_t *, int);
static void display_mbr(u_int8_t *);
static int boot0version(const u_int8_t *);
static int boot0bs(const u_int8_t *);
static void stropt(const char *, int *, int *);
static char *mkrdev(const char *);
static int argtoi(const char *, int, int, int);
static void usage(void);

/*
 * Boot manager installation/configuration utility.
 */
int
main(int argc, char *argv[])
{
    u_int8_t *mbr, *boot0;
    int boot0_size, mbr_size;
    const char *bpath, *fpath, *disk;
    int B_flag, v_flag, o_flag;
    int d_arg, m_arg, t_arg;
    int o_and, o_or;
    int up, c;

    bpath = "/boot/boot0";
    fpath = NULL;
    B_flag = v_flag = o_flag = 0;
    d_arg = m_arg = t_arg = -1;
    o_and = 0xff;
    o_or = 0;
    while ((c = getopt(argc, argv, "Bvb:d:f:m:o:t:")) != -1)
        switch (c) {
        case 'B':
            B_flag = 1;
            break;
        case 'v':
            v_flag = 1;
            break;
        case 'b':
            bpath = optarg;
            break;
        case 'd':
            d_arg = argtoi(optarg, 0, 0xff, 'd');
            break;
        case 'f':
            fpath = optarg;
            break;
        case 'm':
            m_arg = argtoi(optarg, 0, 0xf, 'm');
            break;
        case 'o':
            stropt(optarg, &o_and, &o_or);
            o_flag = 1;
            break;
        case 't':
            t_arg = argtoi(optarg, 1, 0xffff, 't');
            break;
        default:
            usage();
        }
    argc -= optind;
    argv += optind;
    if (argc != 1)
        usage();
    disk = mkrdev(*argv);
    up = B_flag || d_arg != -1 || m_arg != -1 || o_flag || t_arg != -1;

    /* open the disk and read in the existing mbr */
    mbr_size = read_mbr(disk, &mbr, !B_flag);

    /* save the existing MBR if we are asked to do so */
    if (fpath)
	write_mbr(fpath, O_CREAT | O_TRUNC, mbr, mbr_size);

    /*
     * If we are installing the boot loader, read it from disk and copy the
     * slice table over from the existing MBR.  If not, then point boot0
     * back at the MBR we just read in.  After this, boot0 is the data to
     * write back to disk if we are going to do a write.
     */
    if (B_flag) {
	boot0_size = read_mbr(bpath, &boot0, 1);
        memcpy(boot0 + OFF_PTBL, mbr + OFF_PTBL,
	    sizeof(struct dos_partition) * NDOSPART);
    } else {
	boot0 = mbr;
	boot0_size = mbr_size;
    }

    /* set the drive */
    if (d_arg != -1)
	boot0[OFF_DRIVE] = d_arg;

    /* set various flags */
    if (m_arg != -1) {
	boot0[OFF_FLAGS] &= 0xf0;
	boot0[OFF_FLAGS] |= m_arg;
    }
    if (o_flag) {
        boot0[OFF_FLAGS] &= o_and;
        boot0[OFF_FLAGS] |= o_or;
    }

    /* set the timeout */
    if (t_arg != -1)
        mk2(boot0 + OFF_TICKS, t_arg);

    /* write the MBR back to disk */
    if (up)
	write_mbr(disk, 0, boot0, boot0_size);

    /* display the MBR */
    if (v_flag)
	display_mbr(boot0);

    /* clean up */
    if (mbr != boot0)
	free(boot0);
    free(mbr);

    return 0;
}

/*
 * Read in the MBR of the disk.  If it is boot0, then use the version to
 * read in all of it if necessary.  Use pointers to return a malloc'd
 * buffer containing the MBR and then return its size.
 */
static int
read_mbr(const char *disk, u_int8_t **mbr, int check_version)
{
    u_int8_t buf[MBRSIZE];
    int mbr_size, fd;
    ssize_t n;

    if ((fd = open(disk, O_RDONLY)) == -1)
        err(1, "%s", disk);
    if ((n = read(fd, buf, MBRSIZE)) == -1)
        err(1, "%s", disk);
    if (n != MBRSIZE)
        errx(1, "%s: short read", disk);
    if (cv2(buf + OFF_MAGIC) != 0xaa55)
        errx(1, "%s: bad magic", disk);

    if (!boot0bs(buf)) {
	if (check_version)
	    errx(1, "%s: unknown or incompatible boot code", disk);
    } else if (boot0version(buf) == 0x101) {
	mbr_size = 1024;
	if ((*mbr = malloc(mbr_size)) == NULL)
	    errx(1, "%s: unable to allocate read buffer", disk);
	if (lseek(fd, 0, SEEK_SET) == -1 ||
	    (n = read(fd, *mbr, mbr_size)) == -1)
	    err(1, "%s", disk);
	if (n != mbr_size)
	    errx(1, "%s: short read", disk);
	return (mbr_size);
    }
    *mbr = malloc(sizeof(buf));
    memcpy(*mbr, buf, sizeof(buf));

    return sizeof(buf);
}

/*
 * Write out the mbr to the specified file.
 */
static void
write_mbr(const char *fname, int flags, u_int8_t *mbr, int mbr_size)
{
    int fd;
    ssize_t n;

    if ((fd = open(fname, O_WRONLY | flags, 0666)) == -1 ||
	(n = write(fd, mbr, mbr_size)) == -1 || close(fd))
	err(1, "%s", fname);
    if (n != mbr_size)
	errx(1, "%s: short write", fname);
}

/*
 * Outputs an informative dump of the data in the MBR to stdout.
 */
static void
display_mbr(u_int8_t *mbr)
{
    struct dos_partition *part;
    int i, version;

    part = (struct dos_partition *)(mbr + DOSPARTOFF);
    printf(fmt0);
    for (i = 0; i < NDOSPART; i++)
	if (part[i].dp_typ)
	    printf(fmt1, 1 + i, part[i].dp_flag,
		part[i].dp_scyl + ((part[i].dp_ssect & 0xc0) << 2),
		part[i].dp_shd, part[i].dp_ssect & 0x3f, part[i].dp_typ,
                part[i].dp_ecyl + ((part[i].dp_esect & 0xc0) << 2),
                part[i].dp_ehd, part[i].dp_esect & 0x3f, part[i].dp_start,
                part[i].dp_size);
    printf("\n");
    version = boot0version(mbr);
    printf("version=%d.%d  drive=0x%x  mask=0x%x  ticks=%u\noptions=",
	version >> 8, version & 0xff, mbr[OFF_DRIVE],
	mbr[OFF_FLAGS] & 0xf, cv2(mbr + OFF_TICKS));
    for (i = 0; i < nopt; i++) {
	if (i)
	    printf(",");
	if (!(mbr[OFF_FLAGS] & 1 << (7 - i)) ^ opttbl[i].def)
	    printf("no");
	printf("%s", opttbl[i].tok);
    }
    printf("\n");
}

/*
 * Return the boot0 version with the minor revision in the low byte, and
 * the major revision in the next higher byte.
 */
static int
boot0version(const u_int8_t *bs)
{
    static u_int8_t idold[] = {0xfe, 0x45, 0xf2, 0xe9, 0x00, 0x8a};

    /* Check for old version, and return 0x100 if found. */
    if (memcmp(bs + 0x1c, idold, sizeof(idold)) == 0)
        return 0x100;

    /* We have a newer boot0, so extract the version number and return it. */
    return *(int *)(bs + OFF_VERSION) & 0xffff;
}

/*
 * Decide if we have valid boot0 boot code by looking for
 * characteristic byte sequences at fixed offsets.
 */
static int
boot0bs(const u_int8_t *bs)
{
    static u_int8_t id0[] = {0xfc, 0x31, 0xc0, 0x8e, 0xc0, 0x8e, 0xd8,
			     0x8e, 0xd0, 0xbc, 0x00, 0x7c };
    static u_int8_t id1[] = {'D', 'r', 'i', 'v', 'e', ' '};
    static struct {
	unsigned off;
	unsigned len;
	u_int8_t *key;
    } ident[2] = {
        {0x0,   sizeof(id0), id0},
        {0x1b2, sizeof(id1), id1}
    };
    int i;

    for (i = 0; i < sizeof(ident) / sizeof(ident[0]); i++)
        if (memcmp(bs + ident[i].off, ident[i].key, ident[i].len))
	    return 0;
    return 1;
};

/*
 * Adjust "and" and "or" masks for a -o option argument.
 */
static void
stropt(const char *arg, int *xa, int *xo)
{
    const char *q;
    char *s, *s1;
    int inv, i, x;

    if (!(s = strdup(arg)))
        err(1, NULL);
    for (s1 = s; (q = strtok(s1, ",")); s1 = NULL) {
        if ((inv = !strncmp(q, "no", 2)))
            q += 2;
        for (i = 0; i < nopt; i++)
            if (!strcmp(q, opttbl[i].tok))
                break;
        if (i == nopt)
            errx(1, "%s: Unknown -o option", q);
        if (opttbl[i].def)
            inv ^= 1;
        x = 1 << (7 - i);
        if (inv)
            *xa &= ~x;
        else
            *xo |= x;
    }
    free(s);
}

/*
 * Produce a device path for a "canonical" name, where appropriate.
 */
static char *
mkrdev(const char *fname)
{
    char buf[MAXPATHLEN];
    char *s;

    s = (char *)fname;
    if (!strchr(fname, '/')) {
	snprintf(buf, sizeof(buf), "%s%s", _PATH_DEV, fname);
        if (!(s = strdup(buf)))
            err(1, NULL);
    }
    return s;
}

/*
 * Convert and check an option argument.
 */
static int
argtoi(const char *arg, int lo, int hi, int opt)
{
    char *s;
    long x;

    errno = 0;
    x = strtol(arg, &s, 0);
    if (errno || !*arg || *s || x < lo || x > hi)
        errx(1, "%s: Bad argument to -%c option", arg, opt);
    return x;
}

/*
 * Display usage information.
 */
static void
usage(void)
{
    fprintf(stderr, "%s\n%s\n",
    "usage: boot0cfg [-Bv] [-b boot0] [-d drive] [-f file] [-m mask]",
    "                [-o options] [-t ticks] disk");
    exit(1);
}