mtools/syslinux.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 1998-2007 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 [-sf][-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   int force = 0;                /* -f (force) option */
 133   char mtools_conf[] = "/tmp/syslinux-mtools-XXXXXX";
 134   const char *subdir = NULL;
 135   int mtc_fd;
 136   FILE *mtc, *mtp;
 137   struct libfat_filesystem *fs;
 138   libfat_sector_t s, *secp, sectors[65]; /* 65 is maximum possible */
 139   int32_t ldlinux_cluster;
 140   int nsectors;
 141   const char *errmsg;
 142
 143   (void)argc;                   /* Unused */
 144
 145   mypid = getpid();
 146   program = argv[0];
 147
 148   device = NULL;
 149
 150   for ( argp = argv+1 ; *argp ; argp++ ) {
 151     if ( **argp == '-' ) {
 152       opt = *argp + 1;
 153       if ( !*opt )
 154         usage();
 155
 156       while ( *opt ) {
 157         if ( *opt == 's' ) {
 158           syslinux_make_stupid();       /* Use "safe, slow and stupid" code */
 159         } else if ( *opt == 'f' ) {
 160           force = 1;            /* Force install */
 161         } else if ( *opt == 'd' && argp[1] ) {
 162           subdir = *++argp;
 163         } else if ( *opt == 'o' && argp[1] ) {
 164           filesystem_offset = (off_t)strtoull(*++argp, NULL, 0); /* Byte offset */
 165         } else {
 166           usage();
 167         }
 168         opt++;
 169       }
 170     } else {
 171       if ( device )
 172         usage();
 173       device = *argp;
 174     }
 175   }
 176
 177   if ( !device )
 178     usage();
 179
 180   /*
 181    * First make sure we can open the device at all, and that we have
 182    * read/write permission.
 183    */
 184   dev_fd = open(device, O_RDWR);
 185   if ( dev_fd < 0 || fstat(dev_fd, &st) < 0 ) {
 186     perror(device);
 187     exit(1);
 188   }
 189
 190   if ( !force && !S_ISBLK(st.st_mode) && !S_ISREG(st.st_mode) ) {
 191     fprintf(stderr, "%s: not a block device or regular file (use -f to override)\n", device);
 192     exit(1);
 193   }
 194
 195   xpread(dev_fd, sectbuf, 512, filesystem_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   mtc_fd = mkstemp(mtools_conf);
 208   if ( mtc_fd < 0 || !(mtc = fdopen(mtc_fd, "w")) ) {
 209     perror(program);
 210     exit(1);
 211   }
 212   fprintf(mtc,
 213           "MTOOLS_NO_VFAT=1\n"
 214           "MTOOLS_SKIP_CHECK=1\n" /* Needed for some flash memories */
 215           "drive s:\n"
 216           "  file=\"/proc/%lu/fd/%d\"\n"
 217           "  offset=%llu\n",
 218           (unsigned long)mypid,
 219           dev_fd,
 220           (unsigned long long)filesystem_offset);
 221   fclose(mtc);
 222
 223   /*
 224    * Run mtools to create the LDLINUX.SYS file
 225    */
 226   if ( setenv("MTOOLSRC", mtools_conf, 1) ) {
 227     perror(program);
 228     exit(1);
 229   }
 230
 231   /* This command may fail legitimately */
 232   system("mattrib -h -r -s s:/ldlinux.sys 2>/dev/null");
 233
 234   mtp = popen("mcopy -D o -D O -o - s:/ldlinux.sys", "w");
 235   if ( !mtp ||
 236        (fwrite(syslinux_ldlinux, 1, syslinux_ldlinux_len, mtp)
 237         != syslinux_ldlinux_len) ||
 238        (status = pclose(mtp), !WIFEXITED(status) || WEXITSTATUS(status)) ) {
 239     die("failed to create ldlinux.sys");
 240   }
 241
 242   /*
 243    * Now, use libfat to create a block map
 244    */
 245   fs = libfat_open(libfat_xpread, dev_fd);
 246   ldlinux_cluster = libfat_searchdir(fs, 0, "LDLINUX SYS", NULL);
 247   secp = sectors;
 248   nsectors = 0;
 249   s = libfat_clustertosector(fs, ldlinux_cluster);
 250   while ( s && nsectors < 65 ) {
 251     *secp++ = s;
 252     nsectors++;
 253     s = libfat_nextsector(fs, s);
 254   }
 255   libfat_close(fs);
 256
 257   /* Patch ldlinux.sys and the boot sector */
 258   syslinux_patch(sectors, nsectors);
 259
 260   /* Write the now-patched first sector of ldlinux.sys */
 261   xpwrite(dev_fd, syslinux_ldlinux, 512,
 262           filesystem_offset + ((off_t)sectors[0] << 9));
 263
 264   /* Move ldlinux.sys to the desired location */
 265   if (subdir) {
 266     char target_file[4096], command[5120];
 267     char *cp = target_file, *ep = target_file+sizeof target_file-16;
 268     const char *sd;
 269     int slash = 1;
 270
 271     cp += sprintf(cp, "'s:/");
 272     for (sd = subdir; *sd; sd++) {
 273       if (*sd == '/' || *sd == '\\') {
 274         if (slash)
 275           continue;             /* Remove duplicated slashes */
 276         slash = 1;
 277       } else if (*sd == '\'' || *sd == '!') {
 278         slash = 0;
 279         if (cp < ep) *cp++ = '\'';
 280         if (cp < ep) *cp++ = '\\';
 281         if (cp < ep) *cp++ = *sd;
 282         if (cp < ep) *cp++ = '\'';
 283         continue;
 284       } else {
 285         slash = 0;
 286       }
 287
 288       if (cp < ep)
 289         *cp++ = *sd;
 290     }
 291     if (!slash)
 292       *cp++ = '/';
 293     strcpy(cp, "ldlinux.sys'");
 294
 295     /* This command may fail legitimately */
 296     sprintf(command, "mattrib -h -r -s %s 2>/dev/null", target_file);
 297     system(command);
 298
 299     sprintf(command, "mmove -D o -D O s:/ldlinux.sys %s", target_file);
 300     status = system(command);
 301
 302     if ( !WIFEXITED(status) || WEXITSTATUS(status) ) {
 303       fprintf(stderr,
 304               "%s: warning: unable to move ldlinux.sys\n",
 305             program);
 306
 307       status = system("mattrib +r +h +s s:/ldlinux.sys");
 308     } else {
 309       sprintf(command, "mattrib +r +h +s %s", target_file);
 310       status = system(command);
 311     }
 312   } else {
 313     status = system("mattrib +r +h +s s:/ldlinux.sys");
 314   }
 315
 316   if ( !WIFEXITED(status) || WEXITSTATUS(status) ) {
 317     fprintf(stderr,
 318             "%s: warning: failed to set system bit on ldlinux.sys\n",
 319             program);
 320   }
 321
 322
 323   /*
 324    * Cleanup
 325    */
 326   unlink(mtools_conf);
 327
 328   /*
 329    * To finish up, write the boot sector
 330    */
 331
 332   /* Read the superblock again since it might have changed while mounted */
 333   xpread(dev_fd, sectbuf, 512, filesystem_offset);
 334
 335   /* Copy the syslinux code into the boot sector */
 336   syslinux_make_bootsect(sectbuf);
 337
 338   /* Write new boot sector */
 339   xpwrite(dev_fd, sectbuf, 512, filesystem_offset);
 340
 341   close(dev_fd);
 342   sync();
 343
 344   /* Done! */
 345
 346   return 0;
 347 }