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