mtools/syslinux.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 1998-2008 H. Peter Anvin - All Rights Reserved
   4  *
   5  *   This program is free software; you can redistribute it and/or modify
   6  *   it under the terms of the GNU General Public License as published by
   7  *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
   8  *   Boston MA 02111-1307, USA; either version 2 of the License, or
   9  *   (at your option) any later version; incorporated herein by reference.
  10  *
  11  * ----------------------------------------------------------------------- */
  12
  13 /*
  14  * syslinux.c - Linux installer program for SYSLINUX
  15  *
  16  * This program now requires mtools.  It turned out to be a lot
  17  * easier to deal with than dealing with needing mount privileges.
  18  * We need device write permission anyway.
  19  */
  20
  21 #define _XOPEN_SOURCE 500       /* Required on glibc 2.x */
  22 #define _BSD_SOURCE
  23 #include <alloca.h>
  24 #include <errno.h>
  25 #include <fcntl.h>
  26 #include <inttypes.h>
  27 #include <mntent.h>
  28 #include <paths.h>
  29 #include <stdio.h>
  30 #include <string.h>
  31 #include <stdlib.h>
  32 #include <syslog.h>
  33 #include <unistd.h>
  34 #include <sys/types.h>
  35 #include <sys/stat.h>
  36 #include <sys/wait.h>
  37
  38 #include "syslinux.h"
  39 #include "libfat.h"
  40
  41 char *program;                  /* Name of program */
  42 char *device;                   /* Device to install to */
  43 pid_t mypid;
  44 off_t filesystem_offset = 0;    /* Offset of filesystem */
  45
  46 void __attribute__((noreturn)) usage(void)
  47 {
  48   fprintf(stderr, "Usage: %s [-sfr][-d directory][-o offset] device\n", program);
  49   exit(1);
  50 }
  51
  52 void __attribute__((noreturn)) die(const char *msg)
  53 {
  54   fprintf(stderr, "%s: %s\n", program, msg);
  55   exit(1);
  56 }
  57
  58 /*
  59  * read/write wrapper functions
  60  */
  61 ssize_t xpread(int fd, void *buf, size_t count, off_t offset)
  62 {
  63   char *bufp = (char *)buf;
  64   ssize_t rv;
  65   ssize_t done = 0;
  66
  67   while ( count ) {
  68     rv = pread(fd, bufp, count, offset);
  69     if ( rv == 0 ) {
  70       die("short read");
  71     } else if ( rv == -1 ) {
  72       if ( errno == EINTR ) {
  73         continue;
  74       } else {
  75         die(strerror(errno));
  76       }
  77     } else {
  78       bufp += rv;
  79       offset += rv;
  80       done += rv;
  81       count -= rv;
  82     }
  83   }
  84
  85   return done;
  86 }
  87
  88 ssize_t xpwrite(int fd, const void *buf, size_t count, off_t offset)
  89 {
  90   const char *bufp = (const char *)buf;
  91   ssize_t rv;
  92   ssize_t done = 0;
  93
  94   while ( count ) {
  95     rv = pwrite(fd, bufp, count, offset);
  96     if ( rv == 0 ) {
  97       die("short write");
  98     } else if ( rv == -1 ) {
  99       if ( errno == EINTR ) {
 100         continue;
 101       } else {
 102         die(strerror(errno));
 103       }
 104     } else {
 105       bufp += rv;
 106       offset += rv;
 107       done += rv;
 108       count -= rv;
 109     }
 110   }
 111
 112   return done;
 113 }
 114
 115 /*
 116  * Version of the read function suitable for libfat
 117  */
 118 int libfat_xpread(intptr_t pp, void *buf, size_t secsize, libfat_sector_t sector)
 119 {
 120   off_t offset = (off_t)sector * secsize + filesystem_offset;
 121   return xpread(pp, buf, secsize, offset);
 122 }
 123
 124
 125 int main(int argc, char *argv[])
 126 {
 127   static unsigned char sectbuf[512];
 128   int dev_fd;
 129   struct stat st;
 130   int status;
 131   char **argp, *opt;
 132   char mtools_conf[] = "/tmp/syslinux-mtools-XXXXXX";
 133   const char *subdir = NULL;
 134   int mtc_fd;
 135   FILE *mtc, *mtp;
 136   struct libfat_filesystem *fs;
 137   libfat_sector_t s, *secp, sectors[65]; /* 65 is maximum possible */
 138   int32_t ldlinux_cluster;
 139   int nsectors;
 140   const char *errmsg;
 141
 142   int force = 0;              /* -f (force) option */
 143   int stupid = 0;             /* -s (stupid) option */
 144   int raid_mode = 0;          /* -r (RAID) option */
 145
 146   (void)argc;                   /* Unused */
 147
 148   mypid = getpid();
 149   program = argv[0];
 150
 151   device = NULL;
 152
 153   for ( argp = argv+1 ; *argp ; argp++ ) {
 154     if ( **argp == '-' ) {
 155       opt = *argp + 1;
 156       if ( !*opt )
 157         usage();
 158
 159       while ( *opt ) {
 160         if ( *opt == 's' ) {
 161           stupid = 1;
 162         } else if ( *opt == 'r' ) {
 163           raid_mode = 1;
 164         } else if ( *opt == 'f' ) {
 165           force = 1;            /* Force install */
 166         } else if ( *opt == 'd' && argp[1] ) {
 167           subdir = *++argp;
 168         } else if ( *opt == 'o' && argp[1] ) {
 169           filesystem_offset = (off_t)strtoull(*++argp, NULL, 0); /* Byte offset */
 170         } else {
 171           usage();
 172         }
 173         opt++;
 174       }
 175     } else {
 176       if ( device )
 177         usage();
 178       device = *argp;
 179     }
 180   }
 181
 182   if ( !device )
 183     usage();
 184
 185   /*
 186    * First make sure we can open the device at all, and that we have
 187    * read/write permission.
 188    */
 189   dev_fd = open(device, O_RDWR);
 190   if ( dev_fd < 0 || fstat(dev_fd, &st) < 0 ) {
 191     perror(device);
 192     exit(1);
 193   }
 194
 195   if ( !force && !S_ISBLK(st.st_mode) && !S_ISREG(st.st_mode) ) {
 196     fprintf(stderr, "%s: not a block device or regular file (use -f to override)\n", device);
 197     exit(1);
 198   }
 199
 200   xpread(dev_fd, sectbuf, 512, filesystem_offset);
 201
 202   /*
 203    * Check to see that what we got was indeed an MS-DOS boot sector/superblock
 204    */
 205   if( (errmsg = syslinux_check_bootsect(sectbuf)) ) {
 206     die(errmsg);
 207   }
 208
 209   /*
 210    * Create an mtools configuration file
 211    */
 212   mtc_fd = mkstemp(mtools_conf);
 213   if ( mtc_fd < 0 || !(mtc = fdopen(mtc_fd, "w")) ) {
 214     perror(program);
 215     exit(1);
 216   }
 217   fprintf(mtc,
 218           /* "MTOOLS_NO_VFAT=1\n" */
 219           "MTOOLS_SKIP_CHECK=1\n" /* Needed for some flash memories */
 220           "drive s:\n"
 221           "  file=\"/proc/%lu/fd/%d\"\n"
 222           "  offset=%llu\n",
 223           (unsigned long)mypid,
 224           dev_fd,
 225           (unsigned long long)filesystem_offset);
 226   fclose(mtc);
 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   /* This command may fail legitimately */
 237   system("mattrib -h -r -s s:/ldlinux.sys 2>/dev/null");
 238
 239   mtp = popen("mcopy -D o -D O -o - s:/ldlinux.sys", "w");
 240   if ( !mtp ||
 241        (fwrite(syslinux_ldlinux, 1, syslinux_ldlinux_len, mtp)
 242         != syslinux_ldlinux_len) ||
 243        (status = pclose(mtp), !WIFEXITED(status) || WEXITSTATUS(status)) ) {
 244     die("failed to create ldlinux.sys");
 245   }
 246
 247   /*
 248    * Now, use libfat to create a block map
 249    */
 250   fs = libfat_open(libfat_xpread, dev_fd);
 251   ldlinux_cluster = libfat_searchdir(fs, 0, "LDLINUX SYS", NULL);
 252   secp = sectors;
 253   nsectors = 0;
 254   s = libfat_clustertosector(fs, ldlinux_cluster);
 255   while ( s && nsectors < 65 ) {
 256     *secp++ = s;
 257     nsectors++;
 258     s = libfat_nextsector(fs, s);
 259   }
 260   libfat_close(fs);
 261
 262   /* Patch ldlinux.sys and the boot sector */
 263   syslinux_patch(sectors, nsectors, stupid, raid_mode);
 264
 265   /* Write the now-patched first sector of ldlinux.sys */
 266   xpwrite(dev_fd, syslinux_ldlinux, 512,
 267           filesystem_offset + ((off_t)sectors[0] << 9));
 268
 269   /* Move ldlinux.sys to the desired location */
 270   if (subdir) {
 271     char target_file[4096], command[5120];
 272     char *cp = target_file, *ep = target_file+sizeof target_file-16;
 273     const char *sd;
 274     int slash = 1;
 275
 276     cp += sprintf(cp, "'s:/");
 277     for (sd = subdir; *sd; sd++) {
 278       if (*sd == '/' || *sd == '\\') {
 279         if (slash)
 280           continue;             /* Remove duplicated slashes */
 281         slash = 1;
 282       } else if (*sd == '\'' || *sd == '!') {
 283         slash = 0;
 284         if (cp < ep) *cp++ = '\'';
 285         if (cp < ep) *cp++ = '\\';
 286         if (cp < ep) *cp++ = *sd;
 287         if (cp < ep) *cp++ = '\'';
 288         continue;
 289       } else {
 290         slash = 0;
 291       }
 292
 293       if (cp < ep)
 294         *cp++ = *sd;
 295     }
 296     if (!slash)
 297       *cp++ = '/';
 298     strcpy(cp, "ldlinux.sys'");
 299
 300     /* This command may fail legitimately */
 301     sprintf(command, "mattrib -h -r -s %s 2>/dev/null", target_file);
 302     system(command);
 303
 304     sprintf(command, "mmove -D o -D O s:/ldlinux.sys %s", target_file);
 305     status = system(command);
 306
 307     if ( !WIFEXITED(status) || WEXITSTATUS(status) ) {
 308       fprintf(stderr,
 309               "%s: warning: unable to move ldlinux.sys\n",
 310             program);
 311
 312       status = system("mattrib +r +h +s s:/ldlinux.sys");
 313     } else {
 314       sprintf(command, "mattrib +r +h +s %s", target_file);
 315       status = system(command);
 316     }
 317   } else {
 318     status = system("mattrib +r +h +s s:/ldlinux.sys");
 319   }
 320
 321   if ( !WIFEXITED(status) || WEXITSTATUS(status) ) {
 322     fprintf(stderr,
 323             "%s: warning: failed to set system bit on ldlinux.sys\n",
 324             program);
 325   }
 326
 327
 328   /*
 329    * Cleanup
 330    */
 331   unlink(mtools_conf);
 332
 333   /*
 334    * To finish up, write the boot sector
 335    */
 336
 337   /* Read the superblock again since it might have changed while mounted */
 338   xpread(dev_fd, sectbuf, 512, filesystem_offset);
 339
 340   /* Copy the syslinux code into the boot sector */
 341   syslinux_make_bootsect(sectbuf);
 342
 343   /* Write new boot sector */
 344   xpwrite(dev_fd, sectbuf, 512, filesystem_offset);
 345
 346   close(dev_fd);
 347   sync();
 348
 349   /* Done! */
 350
 351   return 0;
 352 }