/*      $OpenBSD: bootstrap.c,v 1.15 2025/11/19 15:05:04 deraadt Exp $  */

/*
 * Copyright (c) 2013 Joel Sing <jsing@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

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

#include <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "installboot.h"

void
bootstrap(int devfd, char *dev, char *bootfile)
{
        struct disklabel dl;
        struct disklabel *lp;
        struct partition *pp;
        char *boot, *p, part;
        size_t bootsize;
        size_t bootsec;
        struct stat sb;
        int fd, i;

        /*
         * Install bootstrap code onto the given disk, preserving the
         * existing disklabel.
         */

        /* Read disklabel from disk. */
        if (ioctl(devfd, DIOCGDINFO, &dl) == -1)
                err(1, "disklabel");
        if (dl.d_secsize == 0) {
                warnx("disklabel has sector size of 0, assuming %d", DEV_BSIZE);
                dl.d_secsize = DEV_BSIZE;
        }

        /* Read bootstrap file. */
        if (verbose)
                fprintf(stderr, "reading bootstrap from %s\n", bootfile);
        fd = open(bootfile, O_RDONLY);
        if (fd == -1)
                err(1, "open %s", bootfile);
        if (fstat(fd, &sb) == -1)
                err(1, "fstat %s", bootfile);
        bootsec = howmany((ssize_t)sb.st_size, dl.d_secsize);
        bootsize = bootsec * dl.d_secsize;
        if (verbose)
                fprintf(stderr, "bootstrap is %zu bytes "
                    "(%zu sectors @ %u bytes = %zu bytes)\n",
                    (ssize_t)sb.st_size, bootsec, dl.d_secsize, bootsize);
        boot = calloc(1, bootsize);
        if (boot == NULL)
                err(1, "calloc");
        if (read(fd, boot, bootsize) != (ssize_t)sb.st_size)
                err(1, "read");
        close(fd);

        /*
         * Check that the bootstrap will fit - partitions must not overlap,
         * or if they do, the partition type must be either FS_BOOT or
         * FS_UNUSED. The 'c' partition will always overlap and is ignored.
         */
        if (verbose)
                fprintf(stderr, "ensuring used partitions do not overlap "
                    "with bootstrap sectors 0-%zu\n", bootsec);
        for (i = 0; i < dl.d_npartitions; i++) {
                part = DL_PARTNUM2NAME(i);
                pp = &dl.d_partitions[i];
                if (i == RAW_PART)
                        continue;
                if (DL_GETPSIZE(pp) == 0)
                        continue;
                if ((u_int64_t)bootsec <= DL_GETPOFFSET(pp))
                        continue;
                switch (pp->p_fstype) {
                case FS_BOOT:
                        break;
                case FS_UNUSED:
                        warnx("bootstrap overlaps with unused partition %c",
                            part);
                        break;
                default:
                        errx(1, "bootstrap overlaps with partition %c", part);
                }
        }

        /*
         * Make sure the bootstrap has left space for the disklabel.
         * N.B.: LABELSECTOR *is* a DEV_BSIZE quantity!
         */
        lp = (struct disklabel *)(boot + (LABELSECTOR * DEV_BSIZE) +
            LABELOFFSET);
        for (i = 0, p = (char *)lp; i < dl16sz; i++)
                if (p[i] != 0)
                        errx(1, "bootstrap has data in disklabel area");

        /* Patch the disklabel into the bootstrap code. */
        memcpy(lp, &dl, dl16sz);

        /* Write the bootstrap out to the disk. */
        if (verbose)
                fprintf(stderr, "%s bootstrap to disk\n",
                    (nowrite ? "would write" : "writing"));
        if (nowrite)
                return;
        if (pwrite(devfd, boot, bootsize, 0) != (ssize_t)bootsize)
                err(1, "pwrite");
}