dos/syslinux.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 1998-2008 H. Peter Anvin - All Rights Reserved
   4  *   Copyright 2009-2010 Intel Corporation; author: H. Peter Anvin
   5  *
   6  *   This program is free software; you can redistribute it and/or modify
   7  *   it under the terms of the GNU General Public License as published by
   8  *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
   9  *   Boston MA 02111-1307, USA; either version 2 of the License, or
  10  *   (at your option) any later version; incorporated herein by reference.
  11  *
  12  * ----------------------------------------------------------------------- */
  13
  14 /*
  15  * syslinux.c - Linux installer program for SYSLINUX
  16  *
  17  * Hacked up for DOS.
  18  */
  19
  20 #include <errno.h>
  21 #include <getopt.h>
  22 #include <stdio.h>
  23 #include <string.h>
  24 #include <stdlib.h>
  25 #include <stdarg.h>
  26 #include "mystuff.h"
  27
  28 #include "syslinux.h"
  29 #include "libfat.h"
  30 #include "setadv.h"
  31 #include "sysexits.h"
  32 #include "syslxopt.h"
  33 #include "syslxint.h"
  34 #include "syslxfs.h"
  35
  36 char *program = "syslinux.com";         /* Name of program */
  37 uint16_t dos_version;
  38
  39 #ifdef DEBUG
  40 # define dprintf printf
  41 void pause(void)
  42 {
  43     uint16_t ax;
  44
  45     asm volatile("int $0x16" : "=a" (ax) : "a" (0));
  46 }
  47 #else
  48 # define dprintf(...) ((void)0)
  49 # define pause() ((void)0)
  50 #endif
  51
  52 void unlock_device(int);
  53
  54 void __attribute__ ((noreturn)) die(const char *msg)
  55 {
  56     unlock_device(0);
  57     puts("syslinux: ");
  58     puts(msg);
  59     putchar('\n');
  60     exit(1);
  61 }
  62
  63 void warning(const char *msg)
  64 {
  65     puts("syslinux: warning: ");
  66     puts(msg);
  67     putchar('\n');
  68 }
  69
  70 /*
  71  * read/write wrapper functions
  72  */
  73 int creat(const char *filename, int mode)
  74 {
  75     uint16_t rv;
  76     uint8_t err;
  77
  78     dprintf("creat(\"%s\", 0x%x)\n", filename, mode);
  79
  80     rv = 0x3C00;
  81     asm volatile ("int $0x21 ; setc %0"
  82                   : "=bcdm" (err), "+a" (rv)
  83                   : "c" (mode), "d" (filename));
  84     if (err) {
  85         dprintf("rv = %d\n", rv);
  86         die("cannot open ldlinux.sys");
  87     }
  88
  89     return rv;
  90 }
  91
  92 void close(int fd)
  93 {
  94     uint16_t rv = 0x3E00;
  95
  96     dprintf("close(%d)\n", fd);
  97
  98     asm volatile ("int $0x21":"+a" (rv)
  99                   :"b"(fd));
 100
 101     /* The only error MS-DOS returns for close is EBADF,
 102        and we really don't care... */
 103 }
 104
 105 int rename(const char *oldname, const char *newname)
 106 {
 107     uint16_t rv = 0x5600;       /* Also support 43FFh? */
 108     uint8_t err;
 109
 110     dprintf("rename(\"%s\", \"%s\")\n", oldname, newname);
 111
 112     asm volatile ("int $0x21 ; setc %0":"=bcdm" (err), "+a"(rv)
 113                   :"d"(oldname), "D"(newname));
 114
 115     if (err) {
 116         dprintf("rv = %d\n", rv);
 117         warning("cannot move ldlinux.sys");
 118         return rv;
 119     }
 120
 121     return 0;
 122 }
 123
 124 ssize_t write_ldlinux(int fd)
 125 {
 126     uint16_t ldlinux_seg = ((size_t)syslinux_ldlinux >> 4) + ds();
 127     uint32_t offset = 0;
 128     uint16_t rv;
 129     uint8_t err;
 130
 131     while (offset < syslinux_ldlinux_len) {
 132         uint32_t chunk = syslinux_ldlinux_len - offset;
 133         if (chunk > 32768)
 134             chunk = 32768;
 135         asm volatile ("pushw %%ds ; "
 136                       "movw %6,%%ds ; "
 137                       "int $0x21 ; "
 138                       "popw %%ds ; " "setc %0":"=bcdm" (err), "=a"(rv)
 139                       :"a"(0x4000), "b"(fd), "c"(chunk), "d" (offset & 15),
 140                       "SD" ((uint16_t)(ldlinux_seg + (offset >> 4))));
 141         if (err || rv == 0)
 142             die("file write error");
 143         offset += rv;
 144     }
 145
 146     return offset;
 147 }
 148
 149 ssize_t write_file(int fd, const void *buf, size_t count)
 150 {
 151     uint16_t rv;
 152     ssize_t done = 0;
 153     uint8_t err;
 154
 155     dprintf("write_file(%d,%p,%u)\n", fd, buf, count);
 156
 157     while (count) {
 158         asm volatile ("int $0x21 ; setc %0":"=bcdm" (err), "=a"(rv)
 159                       :"a"(0x4000), "b"(fd), "c"(count), "d"(buf));
 160         if (err || rv == 0)
 161             die("file write error");
 162
 163         done += rv;
 164         count -= rv;
 165     }
 166
 167     return done;
 168 }
 169
 170 static inline __attribute__ ((const))
 171 uint16_t data_segment(void)
 172 {
 173     uint16_t ds;
 174
 175     asm("movw %%ds,%0" : "=rm"(ds));
 176     return ds;
 177 }
 178
 179 void write_device(int drive, const void *buf, size_t nsecs, unsigned int sector)
 180 {
 181     uint16_t errnum = 0x0001;
 182     struct diskio dio;
 183
 184     dprintf("write_device(%d,%p,%u,%u)\n", drive, buf, nsecs, sector);
 185
 186     dio.startsector = sector;
 187     dio.sectors = nsecs;
 188     dio.bufoffs = (uintptr_t) buf;
 189     dio.bufseg = data_segment();
 190
 191     if (dos_version >= 0x070a) {
 192         /* Try FAT32-aware system call first */
 193         asm volatile("int $0x21 ; jc 1f ; xorw %0,%0\n"
 194                      "1:"
 195                      : "=a" (errnum)
 196                      : "a" (0x7305), "b" (&dio), "c" (-1), "d" (drive),
 197                        "S" (1), "m" (dio)
 198                      : "memory");
 199         dprintf(" rv(7305) = %04x", errnum);
 200     }
 201
 202     /* If not supported, try the legacy system call (int2526.S) */
 203     if (errnum == 0x0001)
 204         errnum = int26_write_sector(drive, &dio);
 205
 206     if (errnum) {
 207         dprintf("rv = %04x\n", errnum);
 208         die("sector write error");
 209     }
 210 }
 211
 212 void read_device(int drive, void *buf, size_t nsecs, unsigned int sector)
 213 {
 214     uint16_t errnum = 0x0001;
 215     struct diskio dio;
 216
 217     dprintf("read_device(%d,%p,%u,%u)\n", drive, buf, nsecs, sector);
 218
 219     dio.startsector = sector;
 220     dio.sectors = nsecs;
 221     dio.bufoffs = (uintptr_t) buf;
 222     dio.bufseg = data_segment();
 223
 224     if (dos_version >= 0x070a) {
 225         /* Try FAT32-aware system call first */
 226         asm volatile("int $0x21 ; jc 1f ; xorw %0,%0\n"
 227                      "1:"
 228                      : "=a" (errnum)
 229                      : "a" (0x7305), "b" (&dio), "c" (-1), "d" (drive),
 230                        "S" (0), "m" (dio));
 231         dprintf(" rv(7305) = %04x", errnum);
 232     }
 233
 234     /* If not supported, try the legacy system call (int2526.S) */
 235     if (errnum == 0x0001)
 236         errnum = int25_read_sector(drive, &dio);
 237
 238     if (errnum) {
 239         dprintf("rv = %04x\n", errnum);
 240         die("sector read error");
 241     }
 242 }
 243
 244 /* Both traditional DOS and FAT32 DOS return this structure, but
 245    FAT32 return a lot more data, so make sure we have plenty of space */
 246 struct deviceparams {
 247     uint8_t specfunc;
 248     uint8_t devtype;
 249     uint16_t devattr;
 250     uint16_t cylinders;
 251     uint8_t mediatype;
 252     uint16_t bytespersec;
 253     uint8_t secperclust;
 254     uint16_t ressectors;
 255     uint8_t fats;
 256     uint16_t rootdirents;
 257     uint16_t sectors;
 258     uint8_t media;
 259     uint16_t fatsecs;
 260     uint16_t secpertrack;
 261     uint16_t heads;
 262     uint32_t hiddensecs;
 263     uint32_t hugesectors;
 264     uint8_t lotsofpadding[224];
 265 } __attribute__ ((packed));
 266
 267 uint32_t get_partition_offset(int drive)
 268 {
 269     uint8_t err;
 270     uint16_t rv;
 271     struct deviceparams dp;
 272
 273     dp.specfunc = 1;            /* Get current information */
 274
 275     rv = 0x440d;
 276     asm volatile ("int $0x21 ; setc %0"
 277                   :"=abcdm" (err), "+a"(rv), "=m"(dp)
 278                   :"b" (drive), "c" (0x0860), "d" (&dp));
 279
 280     if (!err)
 281         return dp.hiddensecs;
 282
 283     rv = 0x440d;
 284     asm volatile ("int $0x21 ; setc %0"
 285                   : "=abcdm" (err), "+a" (rv), "=m" (dp)
 286                   : "b" (drive), "c" (0x4860), "d" (&dp));
 287
 288     if (!err)
 289         return dp.hiddensecs;
 290
 291     die("could not find partition start offset");
 292 }
 293
 294 struct rwblock {
 295     uint8_t special;
 296     uint16_t head;
 297     uint16_t cylinder;
 298     uint16_t firstsector;
 299     uint16_t sectors;
 300     uint16_t bufferoffset;
 301     uint16_t bufferseg;
 302 } __attribute__ ((packed));
 303
 304 static struct rwblock mbr = {
 305     .special = 0,
 306     .head = 0,
 307     .cylinder = 0,
 308     .firstsector = 0,           /* MS-DOS, unlike the BIOS, zero-base sectors */
 309     .sectors = 1,
 310     .bufferoffset = 0,
 311     .bufferseg = 0
 312 };
 313
 314 void write_mbr(int drive, const void *buf)
 315 {
 316     uint16_t rv;
 317     uint8_t err;
 318
 319     dprintf("write_mbr(%d,%p)", drive, buf);
 320
 321     mbr.bufferoffset = (uintptr_t) buf;
 322     mbr.bufferseg = data_segment();
 323
 324     rv = 0x440d;
 325     asm volatile ("int $0x21 ; setc %0" : "=bcdm" (err), "+a"(rv)
 326                   :"c"(0x0841), "d"(&mbr), "b"(drive), "m"(mbr));
 327
 328     dprintf(" rv(0841) = %04x", rv);
 329     if (!err) {
 330         dprintf("\n");
 331         return;
 332     }
 333
 334     rv = 0x440d;
 335     asm volatile ("int $0x21 ; setc %0" : "=bcdm" (err), "+a"(rv)
 336                   :"c"(0x4841), "d"(&mbr), "b"(drive), "m"(mbr));
 337
 338     dprintf(" rv(4841) = %04x\n", rv);
 339     if (err)
 340         die("mbr write error");
 341 }
 342
 343 void read_mbr(int drive, const void *buf)
 344 {
 345     uint16_t rv;
 346     uint8_t err;
 347
 348     dprintf("read_mbr(%d,%p)", drive, buf);
 349
 350     mbr.bufferoffset = (uintptr_t) buf;
 351     mbr.bufferseg = data_segment();
 352
 353     rv = 0x440d;
 354     asm volatile ("int $0x21 ; setc %0":"=abcdm" (err), "+a"(rv)
 355                   :"c"(0x0861), "d"(&mbr), "b"(drive), "m"(mbr));
 356
 357     dprintf(" rv(0861) = %04x", rv);
 358     if (!err) {
 359         dprintf("\n");
 360         return;
 361     }
 362
 363     rv = 0x440d;
 364     asm volatile ("int $0x21 ; setc %0":"=abcdm" (err), "+a"(rv)
 365                   :"c"(0x4861), "d"(&mbr), "b"(drive), "m"(mbr));
 366
 367     dprintf(" rv(4841) = %04x\n", rv);
 368     if (err)
 369         die("mbr read error");
 370
 371     dprintf("Bytes: %02x %02x %02x %02x %02x %02x %02x %02x\n",
 372             ((const uint8_t *)buf)[0],
 373             ((const uint8_t *)buf)[1],
 374             ((const uint8_t *)buf)[2],
 375             ((const uint8_t *)buf)[3],
 376             ((const uint8_t *)buf)[4],
 377             ((const uint8_t *)buf)[5],
 378             ((const uint8_t *)buf)[6],
 379             ((const uint8_t *)buf)[7]);
 380 }
 381
 382 /* This call can legitimately fail, and we don't care, so ignore error return */
 383 void set_attributes(const char *file, int attributes)
 384 {
 385     uint16_t rv = 0x4301;
 386
 387     dprintf("set_attributes(\"%s\", 0x%02x)\n", file, attributes);
 388
 389     asm volatile ("int $0x21":"+a" (rv)
 390                   :"c"(attributes), "d"(file));
 391 }
 392
 393 /*
 394  * Version of the read_device function suitable for libfat
 395  */
 396 int libfat_xpread(intptr_t pp, void *buf, size_t secsize,
 397                   libfat_sector_t sector)
 398 {
 399     read_device(pp, buf, 1, sector);
 400     return secsize;
 401 }
 402
 403 static inline void get_dos_version(void)
 404 {
 405     uint16_t ver;
 406
 407     asm("int $0x21 ; xchgb %%ah,%%al"
 408         : "=a" (ver)
 409         : "a" (0x3001)
 410         : "ebx", "ecx");
 411     dos_version = ver;
 412
 413     dprintf("DOS version %d.%d\n", (dos_version >> 8), dos_version & 0xff);
 414 }
 415
 416 /* The locking interface relies on static variables.  A massive hack :( */
 417 static uint8_t lock_level, lock_drive;
 418
 419 static inline void set_lock_device(uint8_t device)
 420 {
 421     lock_level  = 0;
 422     lock_drive = device;
 423 }
 424
 425 static int do_lock(uint8_t level)
 426 {
 427     uint16_t level_arg = lock_drive + (level << 8);
 428     uint16_t rv;
 429     uint8_t err;
 430 #if 0
 431     /* DOS 7.10 = Win95 OSR2 = first version with FAT32 */
 432     uint16_t lock_call = (dos_version >= 0x070a) ? 0x484A : 0x084A;
 433 #else
 434     uint16_t lock_call = 0x084A; /* MSDN says this is OK for all filesystems */
 435 #endif
 436
 437     dprintf("Trying lock %04x... ", level_arg);
 438     asm volatile ("int $0x21 ; setc %0"
 439                   : "=bcdm" (err), "=a" (rv)
 440                   : "a" (0x440d), "b" (level_arg),
 441                     "c" (lock_call), "d" (0x0001));
 442     dprintf("%s %04x\n", err ? "err" : "ok", rv);
 443
 444     return err ? rv : 0;
 445 }
 446
 447 void lock_device(int level)
 448 {
 449     static int hard_lock = 0;
 450     int err;
 451
 452     if (dos_version < 0x0700)
 453         return;                 /* Win9x/NT only */
 454
 455     if (!hard_lock) {
 456         /* Assume hierarchial "soft" locking supported */
 457
 458         while (lock_level < level) {
 459             int new_level = lock_level + 1;
 460             err = do_lock(new_level);
 461             if (err) {
 462                 if (err == 0x0001) {
 463                     /* Try hard locking next */
 464                     hard_lock = 1;
 465                 }
 466                 goto soft_fail;
 467             }
 468
 469             lock_level = new_level;
 470         }
 471         return;
 472     }
 473
 474 soft_fail:
 475     if (hard_lock) {
 476         /* Hard locking, only level 4 supported */
 477         /* This is needed for Win9x in DOS mode */
 478
 479         err = do_lock(4);
 480         if (err) {
 481             if (err == 0x0001) {
 482                 /* Assume locking is not needed */
 483                 return;
 484             }
 485             goto hard_fail;
 486         }
 487
 488         lock_level = 4;
 489         return;
 490     }
 491
 492 hard_fail:
 493     die("could not lock device");
 494 }
 495
 496 void unlock_device(int level)
 497 {
 498     uint16_t rv;
 499     uint8_t err;
 500     uint16_t unlock_call;
 501
 502     if (dos_version < 0x0700)
 503         return;                 /* Win9x/NT only */
 504
 505 #if 0
 506     /* DOS 7.10 = Win95 OSR2 = first version with FAT32 */
 507     unlock_call = (dos_version >= 0x070a) ? 0x486A : 0x086A;
 508 #else
 509     unlock_call = 0x086A;       /* MSDN says this is OK for all filesystems */
 510 #endif
 511
 512     if (lock_level == 4 && level > 0)
 513         return;                 /* Only drop the hard lock at the end */
 514
 515     while (lock_level > level) {
 516         uint8_t new_level = (lock_level == 4) ? 0 : lock_level - 1;
 517         uint16_t level_arg = (new_level << 8) + lock_drive;
 518         rv = 0x440d;
 519         dprintf("Trying unlock %04x... ", new_level);
 520         asm volatile ("int $0x21 ; setc %0"
 521                       : "=bcdm" (err), "+a" (rv)
 522                       : "b" (level_arg), "c" (unlock_call));
 523         dprintf("%s %04x\n", err ? "err" : "ok", rv);
 524         lock_level = new_level;
 525     }
 526 }
 527
 528 /*
 529  * This function does any desired MBR manipulation; called with the device lock held.
 530  */
 531 struct mbr_entry {
 532     uint8_t active;             /* Active flag */
 533     uint8_t bhead;              /* Begin head */
 534     uint8_t bsector;            /* Begin sector */
 535     uint8_t bcylinder;          /* Begin cylinder */
 536     uint8_t filesystem;         /* Filesystem value */
 537     uint8_t ehead;              /* End head */
 538     uint8_t esector;            /* End sector */
 539     uint8_t ecylinder;          /* End cylinder */
 540     uint32_t startlba;          /* Start sector LBA */
 541     uint32_t sectors;           /* Length in sectors */
 542 } __attribute__ ((packed));
 543
 544 static void adjust_mbr(int device, int writembr, int set_active)
 545 {
 546     static unsigned char sectbuf[SECTOR_SIZE];
 547     int i;
 548
 549     if (!writembr && !set_active)
 550         return;                 /* Nothing to do */
 551
 552     read_mbr(device, sectbuf);
 553
 554     if (writembr) {
 555         memcpy(sectbuf, syslinux_mbr, syslinux_mbr_len);
 556         *(uint16_t *) (sectbuf + 510) = 0xaa55;
 557     }
 558
 559     if (set_active) {
 560         uint32_t offset = get_partition_offset(device);
 561         struct mbr_entry *me = (struct mbr_entry *)(sectbuf + 446);
 562         int found = 0;
 563
 564         dprintf("Searching for partition offset: %08x\n", offset);
 565
 566         for (i = 0; i < 4; i++) {
 567             if (me->startlba == offset) {
 568                 me->active = 0x80;
 569                 found++;
 570             } else {
 571                 me->active = 0;
 572             }
 573             me++;
 574         }
 575
 576         if (found < 1) {
 577             die("partition not found (-a is not implemented for logical partitions)");
 578         } else if (found > 1) {
 579             die("multiple aliased partitions found");
 580         }
 581     }
 582
 583     write_mbr(device, sectbuf);
 584 }
 585
 586 int main(int argc, char *argv[])
 587 {
 588     static unsigned char sectbuf[SECTOR_SIZE];
 589     int dev_fd, fd;
 590     static char ldlinux_name[] = "@:\\ldlinux.sys";
 591     struct libfat_filesystem *fs;
 592     libfat_sector_t s, *secp;
 593     libfat_sector_t *sectors;
 594     int ldlinux_sectors;
 595     int32_t ldlinux_cluster;
 596     int nsectors;
 597     const char *errmsg;
 598     int i;
 599     int patch_sectors;
 600     unsigned char *dp;
 601
 602     dprintf("argv = %p\n", argv);
 603     for (i = 0; i <= argc; i++)
 604         dprintf("argv[%d] = %p = \"%s\"\n", i, argv[i], argv[i]);
 605
 606     get_dos_version();
 607
 608     argv[0] = program;
 609     parse_options(argc, argv, MODE_SYSLINUX_DOSWIN);
 610
 611     if (!opt.device)
 612         usage(EX_USAGE, MODE_SYSLINUX_DOSWIN);
 613     if (opt.sectors || opt.heads || opt.reset_adv || opt.set_once
 614         || (opt.update_only > 0) || opt.menu_save || opt.offset) {
 615         fprintf(stderr,
 616                 "At least one specified option not yet implemented"
 617                 " for this installer.\n");
 618         exit(1);
 619     }
 620
 621     /*
 622      * Create an ADV in memory... this should be smarter.
 623      */
 624     syslinux_reset_adv(syslinux_adv);
 625
 626     /*
 627      * Figure out which drive we're talking to
 628      */
 629     dev_fd = (opt.device[0] & ~0x20) - 0x40;
 630     if (dev_fd < 1 || dev_fd > 26 || opt.device[1] != ':' || opt.device[2])
 631         usage(EX_USAGE, MODE_SYSLINUX_DOSWIN);
 632
 633     set_lock_device(dev_fd);
 634
 635     lock_device(2);             /* Make sure we can lock the device */
 636     read_device(dev_fd, sectbuf, 1, 0);
 637     unlock_device(1);
 638
 639     /*
 640      * Check to see that what we got was indeed an MS-DOS boot sector/superblock
 641      */
 642     if ((errmsg = syslinux_check_bootsect(sectbuf, NULL))) {
 643         unlock_device(0);
 644         puts(errmsg);
 645         putchar('\n');
 646         exit(1);
 647     }
 648
 649     ldlinux_name[0] = dev_fd | 0x40;
 650
 651     set_attributes(ldlinux_name, 0);
 652     fd = creat(ldlinux_name, 0);        /* SYSTEM HIDDEN READONLY */
 653     write_ldlinux(fd);
 654     write_file(fd, syslinux_adv, 2 * ADV_SIZE);
 655     close(fd);
 656     set_attributes(ldlinux_name, 0x07); /* SYSTEM HIDDEN READONLY */
 657
 658     /*
 659      * Now, use libfat to create a block map.  This probably
 660      * should be changed to use ioctl(...,FIBMAP,...) since
 661      * this is supposed to be a simple, privileged version
 662      * of the installer.
 663      */
 664     ldlinux_sectors = (syslinux_ldlinux_len + 2 * ADV_SIZE
 665                        + SECTOR_SIZE - 1) >> SECTOR_SHIFT;
 666     sectors = calloc(ldlinux_sectors, sizeof *sectors);
 667     lock_device(2);
 668     fs = libfat_open(libfat_xpread, dev_fd);
 669     ldlinux_cluster = libfat_searchdir(fs, 0, "LDLINUX SYS", NULL);
 670     secp = sectors;
 671     nsectors = 0;
 672     s = libfat_clustertosector(fs, ldlinux_cluster);
 673     while (s && nsectors < ldlinux_sectors) {
 674         *secp++ = s;
 675         nsectors++;
 676         s = libfat_nextsector(fs, s);
 677     }
 678     libfat_close(fs);
 679
 680     /*
 681      * If requested, move ldlinux.sys
 682      */
 683     if (opt.directory) {
 684         char new_ldlinux_name[160];
 685         char *cp = new_ldlinux_name + 3;
 686         const char *sd;
 687         int slash = 1;
 688
 689         new_ldlinux_name[0] = dev_fd | 0x40;
 690         new_ldlinux_name[1] = ':';
 691         new_ldlinux_name[2] = '\\';
 692
 693         for (sd = opt.directory; *sd; sd++) {
 694             char c = *sd;
 695
 696             if (c == '/' || c == '\\') {
 697                 if (slash)
 698                     continue;
 699                 c = '\\';
 700                 slash = 1;
 701             } else {
 702                 slash = 0;
 703             }
 704
 705             *cp++ = c;
 706         }
 707
 708         /* Skip if subdirectory == root */
 709         if (cp > new_ldlinux_name + 3) {
 710             if (!slash)
 711                 *cp++ = '\\';
 712
 713             memcpy(cp, "ldlinux.sys", 12);
 714
 715             set_attributes(ldlinux_name, 0);
 716             if (rename(ldlinux_name, new_ldlinux_name))
 717                 set_attributes(ldlinux_name, 0x07);
 718             else
 719                 set_attributes(new_ldlinux_name, 0x07);
 720         }
 721     }
 722
 723     /*
 724      * Patch ldlinux.sys and the boot sector
 725      */
 726     i = syslinux_patch(sectors, nsectors, opt.stupid_mode, opt.raid_mode, opt.directory, NULL);
 727     patch_sectors = (i + SECTOR_SIZE - 1) >> SECTOR_SHIFT;
 728
 729     /*
 730      * Overwrite the now-patched ldlinux.sys
 731      */
 732     /* lock_device(3); -- doesn't seem to be needed */
 733     dp = syslinux_ldlinux;
 734     for (i = 0; i < patch_sectors; i++) {
 735         memcpy_from_sl(sectbuf, dp, SECTOR_SIZE);
 736         dp += SECTOR_SIZE;
 737         write_device(dev_fd, sectbuf, 1, sectors[i]);
 738     }
 739
 740     /*
 741      * Muck with the MBR, if desired, while we hold the lock
 742      */
 743     adjust_mbr(dev_fd, opt.install_mbr, opt.activate_partition);
 744
 745     /*
 746      * To finish up, write the boot sector
 747      */
 748
 749     /* Read the superblock again since it might have changed while mounted */
 750     read_device(dev_fd, sectbuf, 1, 0);
 751
 752     /* Copy the syslinux code into the boot sector */
 753     syslinux_make_bootsect(sectbuf, VFAT);
 754
 755     /* Write new boot sector */
 756     if (opt.bootsecfile) {
 757         unlock_device(0);
 758         fd = creat(opt.bootsecfile, 0x20);      /* ARCHIVE */
 759         write_file(fd, sectbuf, SECTOR_SIZE);
 760         close(fd);
 761     } else {
 762         write_device(dev_fd, sectbuf, 1, 0);
 763         unlock_device(0);
 764     }
 765
 766     /* Done! */
 767
 768     return 0;
 769 }