mtools/syslinux.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 1998-2008 H. Peter Anvin - All Rights Reserved
   4  *   Copyright 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  * This program now requires mtools.  It turned out to be a lot
  18  * easier to deal with than dealing with needing mount privileges.
  19  * We need device write permission anyway.
  20  */
  21
  22 #define _GNU_SOURCE
  23 #include <alloca.h>
  24 #include <errno.h>
  25 #include <fcntl.h>
  26 #include <getopt.h>
  27 #include <inttypes.h>
  28 #include <mntent.h>
  29 #include <paths.h>
  30 #include <stdio.h>
  31 #include <string.h>
  32 #include <stdlib.h>
  33 #include <sysexits.h>
  34 #include <syslog.h>
  35 #include <unistd.h>
  36 #include <sys/types.h>
  37 #include <sys/stat.h>
  38 #include <sys/wait.h>
  39
  40 #include "syslinux.h"
  41 #include "libfat.h"
  42 #include "setadv.h"
  43 #include "syslxopt.h"
  44 #include "syslxfs.h"
  45
  46 char *program;                  /* Name of program */
  47 pid_t mypid;
  48
  49 void __attribute__ ((noreturn)) die(const char *msg)
  50 {
  51     fprintf(stderr, "%s: %s\n", program, msg);
  52     exit(1);
  53 }
  54
  55 void __attribute__ ((noreturn)) die_err(const char *msg)
  56 {
  57     fprintf(stderr, "%s: %s: %s\n", program, msg, strerror(errno));
  58     exit(1);
  59 }
  60
  61 /*
  62  * read/write wrapper functions
  63  */
  64 ssize_t xpread(int fd, void *buf, size_t count, off_t offset)
  65 {
  66     char *bufp = (char *)buf;
  67     ssize_t rv;
  68     ssize_t done = 0;
  69
  70     while (count) {
  71         rv = pread(fd, bufp, count, offset);
  72         if (rv == 0) {
  73             die("short read");
  74         } else if (rv == -1) {
  75             if (errno == EINTR) {
  76                 continue;
  77             } else {
  78                 die(strerror(errno));
  79             }
  80         } else {
  81             bufp += rv;
  82             offset += rv;
  83             done += rv;
  84             count -= rv;
  85         }
  86     }
  87
  88     return done;
  89 }
  90
  91 ssize_t xpwrite(int fd, const void *buf, size_t count, off_t offset)
  92 {
  93     const char *bufp = (const char *)buf;
  94     ssize_t rv;
  95     ssize_t done = 0;
  96
  97     while (count) {
  98         rv = pwrite(fd, bufp, count, offset);
  99         if (rv == 0) {
 100             die("short write");
 101         } else if (rv == -1) {
 102             if (errno == EINTR) {
 103                 continue;
 104             } else {
 105                 die(strerror(errno));
 106             }
 107         } else {
 108             bufp += rv;
 109             offset += rv;
 110             done += rv;
 111             count -= rv;
 112         }
 113     }
 114
 115     return done;
 116 }
 117
 118 /*
 119  * Version of the read function suitable for libfat
 120  */
 121 int libfat_xpread(intptr_t pp, void *buf, size_t secsize,
 122                   libfat_sector_t sector)
 123 {
 124     off_t offset = (off_t) sector * secsize + opt.offset;
 125     return xpread(pp, buf, secsize, offset);
 126 }
 127
 128 int main(int argc, char *argv[])
 129 {
 130     static unsigned char sectbuf[SECTOR_SIZE];
 131     int dev_fd;
 132     struct stat st;
 133     int status;
 134     const char *tmpdir;
 135     char *mtools_conf;
 136     int mtc_fd;
 137     FILE *mtc, *mtp;
 138     struct libfat_filesystem *fs;
 139     libfat_sector_t s, *secp;
 140     libfat_sector_t *sectors;
 141     int32_t ldlinux_cluster;
 142     int nsectors;
 143     const char *errmsg;
 144     int ldlinux_sectors, patch_sectors;
 145     int i;
 146
 147     (void)argc;                 /* Unused */
 148
 149     mypid = getpid();
 150     program = argv[0];
 151
 152     parse_options(argc, argv, MODE_SYSLINUX);
 153
 154     if (!opt.device)
 155         usage(EX_USAGE, MODE_SYSLINUX);
 156
 157     if (opt.sectors || opt.heads || opt.reset_adv || opt.set_once
 158         || (opt.update_only > 0) || opt.menu_save) {
 159         fprintf(stderr,
 160                 "At least one specified option not yet implemented"
 161                 " for this installer.\n");
 162         exit(1);
 163     }
 164
 165     /*
 166      * Temp directory of choice...
 167      */
 168     tmpdir = getenv("TMPDIR");
 169     if (!tmpdir) {
 170 #ifdef P_tmpdir
 171         tmpdir = P_tmpdir;
 172 #elif defined(_PATH_TMP)
 173         tmpdir = _PATH_TMP;
 174 #else
 175         tmpdir = "/tmp";
 176 #endif
 177     }
 178
 179     /*
 180      * First make sure we can open the device at all, and that we have
 181      * read/write permission.
 182      */
 183     dev_fd = open(opt.device, O_RDWR);
 184     if (dev_fd < 0 || fstat(dev_fd, &st) < 0) {
 185         die_err(opt.device);
 186         exit(1);
 187     }
 188
 189     if (!opt.force && !S_ISBLK(st.st_mode) && !S_ISREG(st.st_mode)) {
 190         fprintf(stderr,
 191                 "%s: not a block device or regular file (use -f to override)\n",
 192                 opt.device);
 193         exit(1);
 194     }
 195
 196     xpread(dev_fd, sectbuf, SECTOR_SIZE, opt.offset);
 197
 198     /*
 199      * Check to see that what we got was indeed an MS-DOS boot sector/superblock
 200      */
 201     if ((errmsg = syslinux_check_bootsect(sectbuf, NULL))) {
 202         die(errmsg);
 203     }
 204
 205     /*
 206      * Create an mtools configuration file
 207      */
 208     if (asprintf(&mtools_conf, "%s//syslinux-mtools-XXXXXX", tmpdir) < 0 ||
 209         !mtools_conf)
 210         die_err(tmpdir);
 211
 212     mtc_fd = mkstemp(mtools_conf);
 213     if (mtc_fd < 0 || !(mtc = fdopen(mtc_fd, "w")))
 214         die_err(mtools_conf);
 215
 216     fprintf(mtc,
 217             /* These are needed for some flash memories */
 218             "MTOOLS_SKIP_CHECK=1\n"
 219             "MTOOLS_FAT_COMPATIBILITY=1\n"
 220             "drive s:\n"
 221             "  file=\"/proc/%lu/fd/%d\"\n"
 222             "  offset=%llu\n",
 223             (unsigned long)mypid,
 224             dev_fd, (unsigned long long)opt.offset);
 225
 226     if (ferror(mtc) || fclose(mtc))
 227         die_err(mtools_conf);
 228
 229     /*
 230      * Run mtools to create the LDLINUX.SYS file
 231      */
 232     if (setenv("MTOOLSRC", mtools_conf, 1)) {
 233         perror(program);
 234         exit(1);
 235     }
 236
 237     /*
 238      * Create a vacuous ADV in memory.  This should be smarter.
 239      */
 240     syslinux_reset_adv(syslinux_adv);
 241
 242     /* This command may fail legitimately */
 243     status = system("mattrib -h -r -s s:/ldlinux.sys 2>/dev/null");
 244     (void)status;               /* Keep _FORTIFY_SOURCE happy */
 245
 246     mtp = popen("mcopy -D o -D O -o - s:/ldlinux.sys", "w");
 247     if (!mtp ||
 248         fwrite(syslinux_ldlinux, 1, syslinux_ldlinux_len, mtp)
 249                 != syslinux_ldlinux_len ||
 250         fwrite(syslinux_adv, 1, 2 * ADV_SIZE, mtp)
 251                 != 2 * ADV_SIZE ||
 252         (status = pclose(mtp), !WIFEXITED(status) || WEXITSTATUS(status))) {
 253         die("failed to create ldlinux.sys");
 254     }
 255
 256     /*
 257      * Now, use libfat to create a block map
 258      */
 259     ldlinux_sectors = (syslinux_ldlinux_len + 2 * ADV_SIZE
 260                        + SECTOR_SIZE - 1) >> SECTOR_SHIFT;
 261     sectors = calloc(ldlinux_sectors, sizeof *sectors);
 262     fs = libfat_open(libfat_xpread, dev_fd);
 263     ldlinux_cluster = libfat_searchdir(fs, 0, "LDLINUX SYS", NULL);
 264     secp = sectors;
 265     nsectors = 0;
 266     s = libfat_clustertosector(fs, ldlinux_cluster);
 267     while (s && nsectors < ldlinux_sectors) {
 268         *secp++ = s;
 269         nsectors++;
 270         s = libfat_nextsector(fs, s);
 271     }
 272     libfat_close(fs);
 273
 274     /* Patch ldlinux.sys and the boot sector */
 275     i = syslinux_patch(sectors, nsectors, opt.stupid_mode, opt.raid_mode,
 276                        opt.directory, NULL);
 277     patch_sectors = (i + SECTOR_SIZE - 1) >> SECTOR_SHIFT;
 278
 279     /* Write the now-patched first sectors of ldlinux.sys */
 280     for (i = 0; i < patch_sectors; i++) {
 281         xpwrite(dev_fd, syslinux_ldlinux + i * SECTOR_SIZE, SECTOR_SIZE,
 282                 opt.offset + ((off_t) sectors[i] << SECTOR_SHIFT));
 283     }
 284
 285     /* Move ldlinux.sys to the desired location */
 286     if (opt.directory) {
 287         char target_file[4096], command[5120];
 288         char *cp = target_file, *ep = target_file + sizeof target_file - 16;
 289         const char *sd;
 290         int slash = 1;
 291
 292         cp += sprintf(cp, "'s:/");
 293         for (sd = opt.directory; *sd; sd++) {
 294             if (*sd == '/' || *sd == '\\') {
 295                 if (slash)
 296                     continue;   /* Remove duplicated slashes */
 297                 slash = 1;
 298             } else if (*sd == '\'' || *sd == '!') {
 299                 slash = 0;
 300                 if (cp < ep)
 301                     *cp++ = '\'';
 302                 if (cp < ep)
 303                     *cp++ = '\\';
 304                 if (cp < ep)
 305                     *cp++ = *sd;
 306                 if (cp < ep)
 307                     *cp++ = '\'';
 308                 continue;
 309             } else {
 310                 slash = 0;
 311             }
 312
 313             if (cp < ep)
 314                 *cp++ = *sd;
 315         }
 316         if (!slash)
 317             *cp++ = '/';
 318         strcpy(cp, "ldlinux.sys'");
 319
 320         /* This command may fail legitimately */
 321         sprintf(command, "mattrib -h -r -s %s 2>/dev/null", target_file);
 322         status = system(command);
 323         (void)status;           /* Keep _FORTIFY_SOURCE happy */
 324
 325         sprintf(command, "mmove -D o -D O s:/ldlinux.sys %s", target_file);
 326         status = system(command);
 327
 328         if (!WIFEXITED(status) || WEXITSTATUS(status)) {
 329             fprintf(stderr,
 330                     "%s: warning: unable to move ldlinux.sys\n", program);
 331
 332             status = system("mattrib +r +h +s s:/ldlinux.sys");
 333         } else {
 334             sprintf(command, "mattrib +r +h +s %s", target_file);
 335             status = system(command);
 336         }
 337     } else {
 338         status = system("mattrib +r +h +s s:/ldlinux.sys");
 339     }
 340
 341     if (!WIFEXITED(status) || WEXITSTATUS(status)) {
 342         fprintf(stderr,
 343                 "%s: warning: failed to set system bit on ldlinux.sys\n",
 344                 program);
 345     }
 346
 347     /*
 348      * Cleanup
 349      */
 350     unlink(mtools_conf);
 351
 352     /*
 353      * To finish up, write the boot sector
 354      */
 355
 356     /* Read the superblock again since it might have changed while mounted */
 357     xpread(dev_fd, sectbuf, SECTOR_SIZE, opt.offset);
 358
 359     /* Copy the syslinux code into the boot sector */
 360     syslinux_make_bootsect(sectbuf, VFAT);
 361
 362     /* Write new boot sector */
 363     xpwrite(dev_fd, sectbuf, SECTOR_SIZE, opt.offset);
 364
 365     close(dev_fd);
 366     sync();
 367
 368     /* Done! */
 369
 370     return 0;
 371 }