1 2 /* 3 * Copyright (C) 1995, 1997 Wolfgang Solfrank 4 * Copyright (c) 1995 Martin Husemann 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 28 #include <sys/cdefs.h> 29 #ifndef lint 30 __RCSID("$NetBSD: boot.c,v 1.27 2022/08/28 11:32:19 mlelstv Exp $"); 31 #endif /* not lint */ 32 33 #include <stdlib.h> 34 #include <string.h> 35 #include <strings.h> 36 #include <inttypes.h> 37 #include <stdio.h> 38 #include <unistd.h> 39 #include <sys/ioctl.h> 40 #include <sys/dkio.h> 41 42 #include "ext.h" 43 #include "fsutil.h" 44 45 int 46 readboot(int dosfs, struct bootblock *boot) 47 { 48 u_char *block; 49 u_char *fsinfo; 50 u_char *backup; 51 int ret = FSOK; 52 int i, err; 53 u_int secsize; 54 55 secsize = 0; 56 err = ioctl(dosfs, DIOCGSECTORSIZE, &secsize); 57 if (err != 0 || secsize == 0) 58 secsize = DOSBOOTBLOCKSIZE; 59 60 if (secsize < DOSBOOTBLOCKSIZE) 61 pfatal("Invalid sector size %u\n", secsize); 62 63 block = calloc(1, secsize); 64 if (block == NULL) 65 pfatal("Out of memory"); 66 67 if ((size_t)read(dosfs, block, secsize) != secsize) { 68 perr("could not read boot block"); 69 free(block); 70 return FSFATAL; 71 } 72 73 if (block[510] != 0x55 || block[511] != 0xaa) { 74 pfatal("Invalid signature in boot block: %02x%02x", block[511], block[510]); 75 free(block); 76 return FSFATAL; 77 } 78 79 memset(boot, 0, sizeof *boot); 80 boot->ValidFat = -1; 81 82 /* decode bios parameter block */ 83 boot->BytesPerSec = block[11] + (block[12] << 8); 84 boot->SecPerClust = block[13]; 85 if (boot->SecPerClust == 0 || popcount(boot->SecPerClust) != 1) { 86 pfatal("Invalid cluster size: %u\n", boot->SecPerClust); 87 return FSFATAL; 88 } 89 boot->ResSectors = block[14] + (block[15] << 8); 90 boot->FATs = block[16]; 91 if (boot->FATs == 0) { 92 pfatal("Invalid number of FATs: %u\n", boot->FATs); 93 return FSFATAL; 94 } 95 boot->RootDirEnts = block[17] + (block[18] << 8); 96 boot->Sectors = block[19] + (block[20] << 8); 97 boot->Media = block[21]; 98 boot->FATsmall = block[22] + (block[23] << 8); 99 boot->SecPerTrack = block[24] + (block[25] << 8); 100 boot->Heads = block[26] + (block[27] << 8); 101 boot->HiddenSecs = block[28] + (block[29] << 8) + (block[30] << 16) + ((uint32_t)block[31] << 24); 102 boot->HugeSectors = block[32] + (block[33] << 8) + (block[34] << 16) + ((uint32_t)block[35] << 24); 103 104 boot->FATsecs = boot->FATsmall; 105 106 fsinfo = calloc(2, secsize); 107 if (fsinfo == NULL) 108 pfatal("Out of memory"); 109 backup = calloc(1, secsize); 110 if (backup == NULL) 111 pfatal("Out of memory"); 112 113 if (!boot->RootDirEnts) 114 boot->flags |= FAT32; 115 if (boot->flags & FAT32) { 116 boot->FATsecs = block[36] + (block[37] << 8) 117 + (block[38] << 16) + ((uint32_t)block[39] << 24); 118 if (block[40] & 0x80) 119 boot->ValidFat = block[40] & 0x0f; 120 121 /* check version number: */ 122 if (block[42] || block[43]) { 123 /* Correct? XXX */ 124 pfatal("Unknown filesystem version: %x.%x", 125 block[43], block[42]); 126 return FSFATAL; 127 } 128 boot->RootCl = block[44] + (block[45] << 8) 129 + (block[46] << 16) + ((uint32_t)block[47] << 24); 130 boot->FSInfo = block[48] + (block[49] << 8); 131 boot->Backup = block[50] + (block[51] << 8); 132 133 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 134 != boot->FSInfo * boot->BytesPerSec 135 || (size_t)read(dosfs, fsinfo, 2 * secsize) 136 != 2 * secsize) { 137 perr("could not read fsinfo block"); 138 return FSFATAL; 139 } 140 if (memcmp(fsinfo, "RRaA", 4) 141 || memcmp(fsinfo + 0x1e4, "rrAa", 4) 142 || fsinfo[0x1fc] 143 || fsinfo[0x1fd] 144 || fsinfo[0x1fe] != 0x55 145 || fsinfo[0x1ff] != 0xaa 146 || fsinfo[0x3fc] 147 || fsinfo[0x3fd] 148 || fsinfo[0x3fe] != 0x55 149 || fsinfo[0x3ff] != 0xaa) { 150 pwarn("Invalid signature in fsinfo block\n"); 151 if (ask(0, "fix")) { 152 memcpy(fsinfo, "RRaA", 4); 153 memcpy(fsinfo + 0x1e4, "rrAa", 4); 154 fsinfo[0x1fc] = fsinfo[0x1fd] = 0; 155 fsinfo[0x1fe] = 0x55; 156 fsinfo[0x1ff] = 0xaa; 157 fsinfo[0x3fc] = fsinfo[0x3fd] = 0; 158 fsinfo[0x3fe] = 0x55; 159 fsinfo[0x3ff] = 0xaa; 160 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 161 != boot->FSInfo * boot->BytesPerSec 162 || (size_t)write(dosfs, fsinfo, 2 * secsize) 163 != 2 * secsize) { 164 perr("Unable to write FSInfo"); 165 free(fsinfo); 166 free(backup); 167 free(block); 168 return FSFATAL; 169 } 170 ret = FSBOOTMOD; 171 } else 172 boot->FSInfo = 0; 173 } 174 if (boot->FSInfo) { 175 boot->FSFree = fsinfo[0x1e8] + (fsinfo[0x1e9] << 8) 176 + (fsinfo[0x1ea] << 16) 177 + ((uint32_t)fsinfo[0x1eb] << 24); 178 boot->FSNext = fsinfo[0x1ec] + (fsinfo[0x1ed] << 8) 179 + (fsinfo[0x1ee] << 16) 180 + ((uint32_t)fsinfo[0x1ef] << 24); 181 } 182 183 if (lseek(dosfs, boot->Backup * boot->BytesPerSec, SEEK_SET) 184 != boot->Backup * boot->BytesPerSec 185 || (size_t)read(dosfs, backup, secsize) != secsize) { 186 perr("could not read backup bootblock"); 187 free(fsinfo); 188 free(backup); 189 free(block); 190 return FSFATAL; 191 } 192 backup[65] = block[65]; /* XXX */ 193 if (memcmp(block + 11, backup + 11, 79)) { 194 /* 195 * XXX We require a reference that explains 196 * that these bytes need to match, or should 197 * drop the check. gdt@ has observed 198 * filesystems that work fine under Windows XP 199 * and NetBSD that do not match, so the 200 * requirement is suspect. For now, just 201 * print out useful information and continue. 202 */ 203 pfatal("backup (block %d) mismatch with primary bootblock:\n", 204 boot->Backup); 205 for (i = 11; i < 11 + 90; i++) { 206 if (block[i] != backup[i]) 207 pfatal("\ti=%d\tprimary 0x%02x\tbackup 0x%02x\n", 208 i, block[i], backup[i]); 209 } 210 } 211 /* Check backup FSInfo? XXX */ 212 } 213 214 free(fsinfo); 215 free(backup); 216 free(block); 217 218 if (boot->FATsecs == 0) { 219 pfatal("Invalid number of FAT sectors: %u\n", boot->FATsecs); 220 return FSFATAL; 221 } 222 223 boot->FirstCluster = (boot->RootDirEnts * 32 + boot->BytesPerSec - 1) 224 / boot->BytesPerSec 225 + boot->ResSectors 226 + boot->FATs * boot->FATsecs; 227 228 if (boot->BytesPerSec % DOSBOOTBLOCKSIZE != 0) { 229 pfatal("Invalid sector size: %u", boot->BytesPerSec); 230 return FSFATAL; 231 } 232 if (boot->SecPerClust == 0) { 233 pfatal("Invalid cluster size: %u", boot->SecPerClust); 234 return FSFATAL; 235 } 236 if (boot->Sectors) { 237 boot->HugeSectors = 0; 238 boot->NumSectors = boot->Sectors; 239 } else 240 boot->NumSectors = boot->HugeSectors; 241 242 if (boot->FirstCluster + boot->SecPerClust > boot->NumSectors) { 243 pfatal("Cluster offset too large (%u clusters)\n", 244 boot->FirstCluster); 245 return FSFATAL; 246 } 247 248 /* 249 * The number of clusters is derived from available data sectors, 250 * divided by sectors per cluster. 251 */ 252 boot->NumClusters = 253 (boot->NumSectors - boot->FirstCluster) / boot->SecPerClust; 254 255 if (boot->flags&FAT32) 256 boot->ClustMask = CLUST32_MASK; 257 else if (boot->NumClusters < (CLUST_RSRVD&CLUST12_MASK)) 258 boot->ClustMask = CLUST12_MASK; 259 else if (boot->NumClusters < (CLUST_RSRVD&CLUST16_MASK)) 260 boot->ClustMask = CLUST16_MASK; 261 else { 262 pfatal("Filesystem too big (%u clusters) for non-FAT32 partition", 263 boot->NumClusters); 264 return FSFATAL; 265 } 266 267 switch (boot->ClustMask) { 268 case CLUST32_MASK: 269 boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec) / 4; 270 break; 271 case CLUST16_MASK: 272 boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec) / 2; 273 break; 274 default: 275 boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec * 2) / 3; 276 break; 277 } 278 279 if (boot->NumFatEntries < boot->NumClusters) { 280 pfatal("FAT size too small, %u entries won't fit into %u sectors\n", 281 boot->NumClusters, boot->FATsecs); 282 return FSFATAL; 283 } 284 285 /* 286 * There are two reserved clusters. To avoid adding CLUST_FIRST every 287 * time we perform boundary checks, we increment the NumClusters by 2, 288 * which is CLUST_FIRST to denote the first out-of-range cluster number. 289 */ 290 boot->NumClusters += CLUST_FIRST; 291 292 boot->ClusterSize = boot->BytesPerSec * boot->SecPerClust; 293 294 boot->NumFiles = 1; 295 boot->NumFree = 0; 296 297 return ret; 298 } 299 300 int 301 writefsinfo(int dosfs, struct bootblock *boot) 302 { 303 u_char *fsinfo; 304 305 fsinfo = calloc(2, boot->BytesPerSec); 306 if (fsinfo == NULL) 307 pfatal("Out of memory"); 308 309 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 310 != boot->FSInfo * boot->BytesPerSec 311 || (size_t)read(dosfs, fsinfo, 2 * boot->BytesPerSec) 312 != 2 * boot->BytesPerSec) { 313 perr("could not read fsinfo block"); 314 free(fsinfo); 315 return FSFATAL; 316 } 317 fsinfo[0x1e8] = (u_char)boot->FSFree; 318 fsinfo[0x1e9] = (u_char)(boot->FSFree >> 8); 319 fsinfo[0x1ea] = (u_char)(boot->FSFree >> 16); 320 fsinfo[0x1eb] = (u_char)(boot->FSFree >> 24); 321 fsinfo[0x1ec] = (u_char)boot->FSNext; 322 fsinfo[0x1ed] = (u_char)(boot->FSNext >> 8); 323 fsinfo[0x1ee] = (u_char)(boot->FSNext >> 16); 324 fsinfo[0x1ef] = (u_char)(boot->FSNext >> 24); 325 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 326 != boot->FSInfo * boot->BytesPerSec 327 || (size_t)write(dosfs, fsinfo, 2 * boot->BytesPerSec) 328 != 2 * boot->BytesPerSec) { 329 perr("Unable to write FSInfo"); 330 free(fsinfo); 331 return FSFATAL; 332 } 333 334 free(fsinfo); 335 336 /* 337 * Technically, we should return FSBOOTMOD here. 338 * 339 * However, since Win95 OSR2 (the first M$ OS that has 340 * support for FAT32) doesn't maintain the FSINFO block 341 * correctly, it has to be fixed pretty often. 342 * 343 * Therefore, we handle the FSINFO block only informally, 344 * fixing it if necessary, but otherwise ignoring the 345 * fact that it was incorrect. 346 */ 347 return 0; 348 } 349
Indexes created Sun Sep 21 18:09:52 GMT 2025