821d28352b
This should solve the problem of modifying the MBR while running.
471 lines
12 KiB
C
471 lines
12 KiB
C
/*
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* Copyright (c) 1999 Robert Nordier
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
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* OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
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* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/disklabel.h>
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#include <sys/diskmbr.h>
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#include <sys/stat.h>
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#include <err.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <libgeom.h>
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#include <paths.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#define MBRSIZE 512 /* master boot record size */
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#define OFF_VERSION 0x1b0 /* offset: version number */
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#define OFF_OPT 0x1b9 /* offset: default boot option */
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#define OFF_DRIVE 0x1ba /* offset: setdrv drive */
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#define OFF_FLAGS 0x1bb /* offset: option flags */
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#define OFF_TICKS 0x1bc /* offset: clock ticks */
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#define OFF_PTBL 0x1be /* offset: partition table */
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#define OFF_MAGIC 0x1fe /* offset: magic number */
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#define cv2(p) ((p)[0] | (p)[1] << 010)
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#define mk2(p, x) \
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(p)[0] = (u_int8_t)(x), \
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(p)[1] = (u_int8_t)((x) >> 010)
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static const struct {
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const char *tok;
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int def;
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} opttbl[] = {
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{"packet", 0},
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{"update", 1},
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{"setdrv", 0}
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};
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static const int nopt = sizeof(opttbl) / sizeof(opttbl[0]);
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static const char fmt0[] = "# flag start chs type"
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" end chs offset size\n";
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static const char fmt1[] = "%d 0x%02x %4u:%3u:%2u 0x%02x"
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" %4u:%3u:%2u %10u %10u\n";
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static int read_mbr(const char *, u_int8_t **, int);
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static void write_mbr(const char *, int, u_int8_t *, int);
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static void display_mbr(u_int8_t *);
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static int boot0version(const u_int8_t *);
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static int boot0bs(const u_int8_t *);
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static void stropt(const char *, int *, int *);
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static char *mkrdev(const char *);
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static int argtoi(const char *, int, int, int);
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static void usage(void);
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/*
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* Boot manager installation/configuration utility.
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*/
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int
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main(int argc, char *argv[])
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{
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u_int8_t *mbr, *boot0;
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int boot0_size, mbr_size;
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const char *bpath, *fpath;
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char *disk;
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int B_flag, v_flag, o_flag;
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int d_arg, m_arg, s_arg, t_arg;
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int o_and, o_or;
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int up, c;
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bpath = "/boot/boot0";
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fpath = NULL;
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B_flag = v_flag = o_flag = 0;
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d_arg = m_arg = s_arg = t_arg = -1;
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o_and = 0xff;
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o_or = 0;
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while ((c = getopt(argc, argv, "Bvb:d:f:m:o:s:t:")) != -1)
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switch (c) {
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case 'B':
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B_flag = 1;
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break;
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case 'v':
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v_flag = 1;
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break;
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case 'b':
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bpath = optarg;
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break;
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case 'd':
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d_arg = argtoi(optarg, 0, 0xff, 'd');
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break;
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case 'f':
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fpath = optarg;
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break;
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case 'm':
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m_arg = argtoi(optarg, 0, 0xf, 'm');
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break;
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case 'o':
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stropt(optarg, &o_and, &o_or);
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o_flag = 1;
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break;
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case 's':
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s_arg = argtoi(optarg, 1, 5, 's');
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break;
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case 't':
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t_arg = argtoi(optarg, 1, 0xffff, 't');
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break;
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default:
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usage();
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}
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argc -= optind;
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argv += optind;
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if (argc != 1)
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usage();
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disk = mkrdev(*argv);
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up = B_flag || d_arg != -1 || m_arg != -1 || o_flag || s_arg != -1
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|| t_arg != -1;
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/* open the disk and read in the existing mbr */
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mbr_size = read_mbr(disk, &mbr, !B_flag);
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/* save the existing MBR if we are asked to do so */
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if (fpath)
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write_mbr(fpath, O_CREAT | O_TRUNC, mbr, mbr_size);
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/*
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* If we are installing the boot loader, read it from disk and copy the
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* slice table over from the existing MBR. If not, then point boot0
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* back at the MBR we just read in. After this, boot0 is the data to
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* write back to disk if we are going to do a write.
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*/
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if (B_flag) {
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boot0_size = read_mbr(bpath, &boot0, 1);
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memcpy(boot0 + OFF_PTBL, mbr + OFF_PTBL,
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sizeof(struct dos_partition) * NDOSPART);
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} else {
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boot0 = mbr;
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boot0_size = mbr_size;
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}
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/* set the drive */
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if (d_arg != -1)
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boot0[OFF_DRIVE] = d_arg;
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/* set various flags */
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if (m_arg != -1) {
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boot0[OFF_FLAGS] &= 0xf0;
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boot0[OFF_FLAGS] |= m_arg;
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}
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if (o_flag) {
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boot0[OFF_FLAGS] &= o_and;
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boot0[OFF_FLAGS] |= o_or;
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}
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/* set the default boot selection */
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if (s_arg != -1)
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boot0[OFF_OPT] = s_arg - 1;
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/* set the timeout */
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if (t_arg != -1)
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mk2(boot0 + OFF_TICKS, t_arg);
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/* write the MBR back to disk */
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if (up)
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write_mbr(disk, 0, boot0, boot0_size);
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/* display the MBR */
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if (v_flag)
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display_mbr(boot0);
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/* clean up */
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if (mbr != boot0)
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free(boot0);
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free(mbr);
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free(disk);
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return 0;
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}
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/*
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* Read in the MBR of the disk. If it is boot0, then use the version to
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* read in all of it if necessary. Use pointers to return a malloc'd
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* buffer containing the MBR and then return its size.
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*/
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static int
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read_mbr(const char *disk, u_int8_t **mbr, int check_version)
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{
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u_int8_t buf[MBRSIZE];
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int mbr_size, fd;
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ssize_t n;
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if ((fd = open(disk, O_RDONLY)) == -1)
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err(1, "open %s", disk);
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if ((n = read(fd, buf, MBRSIZE)) == -1)
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err(1, "read %s", disk);
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if (n != MBRSIZE)
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errx(1, "%s: short read", disk);
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if (cv2(buf + OFF_MAGIC) != 0xaa55)
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errx(1, "%s: bad magic", disk);
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if (!boot0bs(buf)) {
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if (check_version)
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errx(1, "%s: unknown or incompatible boot code", disk);
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} else if (boot0version(buf) == 0x101) {
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mbr_size = 1024;
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if ((*mbr = malloc(mbr_size)) == NULL)
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errx(1, "%s: unable to allocate read buffer", disk);
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if (lseek(fd, 0, SEEK_SET) == -1 ||
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(n = read(fd, *mbr, mbr_size)) == -1)
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err(1, "%s", disk);
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if (n != mbr_size)
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errx(1, "%s: short read", disk);
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return (mbr_size);
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}
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*mbr = malloc(sizeof(buf));
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memcpy(*mbr, buf, sizeof(buf));
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return sizeof(buf);
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}
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/*
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* Write out the mbr to the specified file.
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*/
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static void
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write_mbr(const char *fname, int flags, u_int8_t *mbr, int mbr_size)
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{
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int fd, p;
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ssize_t n;
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char *s;
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const char *q;
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struct gctl_req *grq;
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fd = open(fname, O_WRONLY | flags, 0666);
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if (fd != -1) {
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n = write(fd, mbr, mbr_size);
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close(fd);
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if (n != mbr_size)
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errx(1, "%s: short write", fname);
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return;
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}
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if (flags != 0)
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err(1, "%s", fname);
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grq = gctl_get_handle();
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gctl_ro_param(grq, "verb", -1, "write MBR");
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gctl_ro_param(grq, "class", -1, "MBR");
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q = strrchr(fname, '/');
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if (q == NULL)
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q = fname;
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else
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q++;
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gctl_ro_param(grq, "geom", -1, q);
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gctl_ro_param(grq, "data", mbr_size, mbr);
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q = gctl_issue(grq);
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if (q == NULL)
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return;
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warnx("%s: %s", fname, q);
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gctl_free(grq);
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#ifdef DIOCSMBR
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for (p = 1; p < 5; p++) {
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asprintf(&s, "%ss%d", fname, p);
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fd = open(s, O_RDONLY);
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if (fd < 0) {
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free(s);
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continue;
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}
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n = ioctl(fd, DIOCSMBR, (mbr));
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if (n != 0)
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err(1, "%s: ioctl DIOCSMBR", fname);
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close(fd);
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free(s);
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return;
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}
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#endif
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err(1, "write_mbr: %s", fname);
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}
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/*
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* Outputs an informative dump of the data in the MBR to stdout.
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*/
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static void
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display_mbr(u_int8_t *mbr)
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{
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struct dos_partition *part;
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int i, version;
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part = (struct dos_partition *)(mbr + DOSPARTOFF);
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printf(fmt0);
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for (i = 0; i < NDOSPART; i++)
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if (part[i].dp_typ)
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printf(fmt1, 1 + i, part[i].dp_flag,
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part[i].dp_scyl + ((part[i].dp_ssect & 0xc0) << 2),
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part[i].dp_shd, part[i].dp_ssect & 0x3f, part[i].dp_typ,
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part[i].dp_ecyl + ((part[i].dp_esect & 0xc0) << 2),
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part[i].dp_ehd, part[i].dp_esect & 0x3f, part[i].dp_start,
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part[i].dp_size);
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printf("\n");
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version = boot0version(mbr);
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printf("version=%d.%d drive=0x%x mask=0x%x ticks=%u\noptions=",
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version >> 8, version & 0xff, mbr[OFF_DRIVE],
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mbr[OFF_FLAGS] & 0xf, cv2(mbr + OFF_TICKS));
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for (i = 0; i < nopt; i++) {
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if (i)
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printf(",");
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if (!(mbr[OFF_FLAGS] & 1 << (7 - i)) ^ opttbl[i].def)
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printf("no");
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printf("%s", opttbl[i].tok);
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}
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printf("\n");
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printf("default_selection=F%d (", mbr[OFF_OPT] + 1);
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if (mbr[OFF_OPT] < 4)
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printf("Slice %d", mbr[OFF_OPT] + 1);
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else
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printf("Drive 1");
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printf(")\n");
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}
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/*
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* Return the boot0 version with the minor revision in the low byte, and
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* the major revision in the next higher byte.
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*/
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static int
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boot0version(const u_int8_t *bs)
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{
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static u_int8_t idold[] = {0xfe, 0x45, 0xf2, 0xe9, 0x00, 0x8a};
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/* Check for old version, and return 0x100 if found. */
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if (memcmp(bs + 0x1c, idold, sizeof(idold)) == 0)
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return 0x100;
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/* We have a newer boot0, so extract the version number and return it. */
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return *(const int *)(bs + OFF_VERSION) & 0xffff;
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}
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/*
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* Decide if we have valid boot0 boot code by looking for
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* characteristic byte sequences at fixed offsets.
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*/
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static int
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boot0bs(const u_int8_t *bs)
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{
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static u_int8_t id0[] = {0xfc, 0x31, 0xc0, 0x8e, 0xc0, 0x8e, 0xd8,
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0x8e, 0xd0, 0xbc, 0x00, 0x7c };
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static u_int8_t id1[] = {'D', 'r', 'i', 'v', 'e', ' '};
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static struct {
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unsigned off;
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unsigned len;
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u_int8_t *key;
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} ident[2] = {
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{0x0, sizeof(id0), id0},
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{0x1b2, sizeof(id1), id1}
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};
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unsigned int i;
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for (i = 0; i < sizeof(ident) / sizeof(ident[0]); i++)
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if (memcmp(bs + ident[i].off, ident[i].key, ident[i].len))
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return 0;
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return 1;
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}
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/*
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* Adjust "and" and "or" masks for a -o option argument.
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*/
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static void
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stropt(const char *arg, int *xa, int *xo)
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{
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const char *q;
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char *s, *s1;
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int inv, i, x;
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if (!(s = strdup(arg)))
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err(1, NULL);
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for (s1 = s; (q = strtok(s1, ",")); s1 = NULL) {
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if ((inv = !strncmp(q, "no", 2)))
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q += 2;
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for (i = 0; i < nopt; i++)
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if (!strcmp(q, opttbl[i].tok))
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break;
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if (i == nopt)
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errx(1, "%s: Unknown -o option", q);
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if (opttbl[i].def)
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inv ^= 1;
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x = 1 << (7 - i);
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if (inv)
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*xa &= ~x;
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else
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*xo |= x;
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}
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free(s);
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}
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/*
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* Produce a device path for a "canonical" name, where appropriate.
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*/
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static char *
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mkrdev(const char *fname)
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{
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char buf[MAXPATHLEN];
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char *s;
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if (!strchr(fname, '/')) {
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snprintf(buf, sizeof(buf), "%s%s", _PATH_DEV, fname);
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s = strdup(buf);
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} else
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s = strdup(fname);
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if (s == NULL)
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errx(1, "No more memory");
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return s;
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}
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/*
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* Convert and check an option argument.
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*/
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static int
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argtoi(const char *arg, int lo, int hi, int opt)
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{
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char *s;
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long x;
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errno = 0;
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x = strtol(arg, &s, 0);
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if (errno || !*arg || *s || x < lo || x > hi)
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errx(1, "%s: Bad argument to -%c option", arg, opt);
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return x;
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}
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/*
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* Display usage information.
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*/
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static void
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usage(void)
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{
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fprintf(stderr, "%s\n%s\n",
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"usage: boot0cfg [-Bv] [-b boot0] [-d drive] [-f file] [-m mask]",
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" [-o options] [-s slice] [-t ticks] disk");
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exit(1);
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}
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