1 /* 2 * Copyright (C) 1995, 1997 Wolfgang Solfrank 3 * Copyright (c) 1995 Martin Husemann 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by Martin Husemann 16 * and Wolfgang Solfrank. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR 22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 34 #include <sys/cdefs.h> 35 #ifndef lint 36 __RCSID("$NetBSD: boot.c,v 1.9 2003/07/24 19:25:46 ws Exp $"); 37 static const char rcsid[] = 38 "$FreeBSD: src/sbin/fsck_msdosfs/boot.c,v 1.4.28.1 2009/04/15 03:14:26 kensmith Exp $"; 39 #endif /* not lint */ 40 41 #include <stdlib.h> 42 #include <string.h> 43 #include <ctype.h> 44 #include <stdio.h> 45 #include <unistd.h> 46 47 #include "ext.h" 48 #include "fsutil.h" 49 50 int 51 readboot(dosfs, boot) 52 int dosfs; 53 struct bootblock *boot; 54 { 55 u_char block[DOSBOOTBLOCKSIZE]; 56 u_char fsinfo[2 * DOSBOOTBLOCKSIZE]; 57 u_char backup[DOSBOOTBLOCKSIZE]; 58 int ret = FSOK; 59 60 if (read(dosfs, block, sizeof block) < sizeof block) { 61 perror("could not read boot block"); 62 exit(2); 63 } 64 65 if (block[510] != 0x55 || block[511] != 0xaa) { 66 pfatal("Invalid signature in boot block: %02x%02x", block[511], block[510]); 67 exit(2); 68 } 69 70 memset(boot, 0, sizeof *boot); 71 boot->ValidFat = -1; 72 73 /* decode bios parameter block */ 74 boot->BytesPerSec = block[11] + (block[12] << 8); 75 boot->SecPerClust = block[13]; 76 boot->ResSectors = block[14] + (block[15] << 8); 77 boot->FATs = block[16]; 78 boot->RootDirEnts = block[17] + (block[18] << 8); 79 boot->Sectors = block[19] + (block[20] << 8); 80 boot->Media = block[21]; 81 boot->FATsmall = block[22] + (block[23] << 8); 82 boot->SecPerTrack = block[24] + (block[25] << 8); 83 boot->Heads = block[26] + (block[27] << 8); 84 boot->HiddenSecs = block[28] + (block[29] << 8) + (block[30] << 16) + (block[31] << 24); 85 boot->HugeSectors = block[32] + (block[33] << 8) + (block[34] << 16) + (block[35] << 24); 86 87 boot->FATsecs = boot->FATsmall; 88 89 if (!boot->RootDirEnts) 90 boot->flags |= FAT32; 91 if (boot->flags & FAT32) { 92 boot->FATsecs = block[36] + (block[37] << 8) 93 + (block[38] << 16) + (block[39] << 24); 94 if (block[40] & 0x80) 95 boot->ValidFat = block[40] & 0x0f; 96 97 /* check version number: */ 98 if (block[42] || block[43]) { 99 /* Correct? XXX */ 100 pfatal("Unknown file system version: %x.%x", 101 block[43], block[42]); 102 exit(2); 103 } 104 boot->RootCl = block[44] + (block[45] << 8) 105 + (block[46] << 16) + (block[47] << 24); 106 boot->FSInfo = block[48] + (block[49] << 8); 107 boot->Backup = block[50] + (block[51] << 8); 108 109 /* If the OEM Name field is EXFAT, it's not FAT32, so bail */ 110 if (!memcmp(&block[3], "EXFAT ", 8)) { 111 pfatal("exFAT filesystem is not supported."); 112 return FSFATAL; 113 } 114 115 /* check basic parameters */ 116 if ((boot->FSInfo == 0) || 117 (boot->BytesPerSec % DOSBOOTBLOCKSIZE != 0) || 118 (boot->BytesPerSec / DOSBOOTBLOCKSIZE == 0) || 119 (boot->SecPerClust == 0)) { 120 /* 121 * Either the BIOS Parameter Block has been corrupted, 122 * or this is not a FAT32 filesystem, most likely an 123 * exFAT filesystem. 124 */ 125 pfatal("Invalid FAT32 Extended BIOS Parameter Block"); 126 return FSFATAL; 127 } 128 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 129 != boot->FSInfo * boot->BytesPerSec 130 || read(dosfs, fsinfo, sizeof fsinfo) 131 != sizeof fsinfo) { 132 perror("could not read fsinfo block"); 133 return FSFATAL; 134 } 135 if (memcmp(fsinfo, "RRaA", 4) 136 || memcmp(fsinfo + 0x1e4, "rrAa", 4) 137 || fsinfo[0x1fc] 138 || fsinfo[0x1fd] 139 || fsinfo[0x1fe] != 0x55 140 || fsinfo[0x1ff] != 0xaa 141 || fsinfo[0x3fc] 142 || fsinfo[0x3fd] 143 || fsinfo[0x3fe] != 0x55 144 || fsinfo[0x3ff] != 0xaa) { 145 pwarn("Invalid signature in fsinfo block\n"); 146 if (ask(1, "fix")) { 147 memcpy(fsinfo, "RRaA", 4); 148 memcpy(fsinfo + 0x1e4, "rrAa", 4); 149 fsinfo[0x1fc] = fsinfo[0x1fd] = 0; 150 fsinfo[0x1fe] = 0x55; 151 fsinfo[0x1ff] = 0xaa; 152 fsinfo[0x3fc] = fsinfo[0x3fd] = 0; 153 fsinfo[0x3fe] = 0x55; 154 fsinfo[0x3ff] = 0xaa; 155 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 156 != boot->FSInfo * boot->BytesPerSec 157 || write(dosfs, fsinfo, sizeof fsinfo) 158 != sizeof fsinfo) { 159 perror("Unable to write FSInfo"); 160 return FSFATAL; 161 } 162 ret = FSBOOTMOD; 163 } else 164 boot->FSInfo = 0; 165 } 166 if (boot->FSInfo) { 167 boot->FSFree = fsinfo[0x1e8] + (fsinfo[0x1e9] << 8) 168 + (fsinfo[0x1ea] << 16) 169 + (fsinfo[0x1eb] << 24); 170 boot->FSNext = fsinfo[0x1ec] + (fsinfo[0x1ed] << 8) 171 + (fsinfo[0x1ee] << 16) 172 + (fsinfo[0x1ef] << 24); 173 } 174 175 if (lseek(dosfs, boot->Backup * boot->BytesPerSec, SEEK_SET) 176 != boot->Backup * boot->BytesPerSec 177 || read(dosfs, backup, sizeof backup) != sizeof backup) { 178 perror("could not read backup bootblock"); 179 return FSFATAL; 180 } 181 backup[65] = block[65]; /* XXX */ 182 if (memcmp(block + 11, backup + 11, 79)) { 183 char tmp[255]; 184 int i; 185 186 /* 187 * For now, lets not bail out if they don't match 188 * It seems a lot of sdcards are formatted with 189 * the backup either empty or containing garbage. 190 */ 191 192 pwarn("Primary/Backup bootblock miscompare\n"); 193 194 strcpy(tmp, ""); 195 pwarn("Primary:\n"); 196 for (i = 0; i < 79; i++) { 197 char tmp2[16]; 198 snprintf(tmp2, sizeof(tmp2), "%.2x ", block[11 + i]); 199 strcat(tmp, tmp2); 200 } 201 pwarn("%s\n", tmp); 202 203 strcpy(tmp, ""); 204 pwarn("Backup:\n"); 205 for (i = 0; i < 79; i++) { 206 char tmp2[16]; 207 snprintf(tmp2, sizeof(tmp2), "%.2x ", backup[11 + i]); 208 strcat(tmp, tmp2); 209 } 210 pwarn("%s\n", tmp); 211 } 212 /* Check backup FSInfo? XXX */ 213 } 214 215 if (boot->BytesPerSec % DOSBOOTBLOCKSIZE != 0) { 216 pfatal("Invalid sector size: %u", boot->BytesPerSec); 217 return FSFATAL; 218 } 219 if (boot->SecPerClust == 0) { 220 pfatal("Invalid cluster size: %u", boot->SecPerClust); 221 return FSFATAL; 222 } 223 if (boot->BytesPerSec == 0) { 224 pfatal("Invalid sector size: %u", boot->BytesPerSec); 225 return FSFATAL; 226 } 227 if (boot->FATs == 0) { 228 pfatal("Invalid number of FATs: %u", boot->FATs); 229 return FSFATAL; 230 } 231 if (boot->Sectors) { 232 boot->HugeSectors = 0; 233 boot->NumSectors = boot->Sectors; 234 } else 235 boot->NumSectors = boot->HugeSectors; 236 237 boot->ClusterOffset = (boot->RootDirEnts * 32 + boot->BytesPerSec - 1) 238 / boot->BytesPerSec 239 + boot->ResSectors 240 + boot->FATs * boot->FATsecs 241 - CLUST_FIRST * boot->SecPerClust; 242 243 boot->NumClusters = (boot->NumSectors - boot->ClusterOffset) / boot->SecPerClust; 244 245 if (boot->flags&FAT32) 246 boot->ClustMask = CLUST32_MASK; 247 else if (boot->NumClusters < (CLUST_RSRVD&CLUST12_MASK)) 248 boot->ClustMask = CLUST12_MASK; 249 else if (boot->NumClusters < (CLUST_RSRVD&CLUST16_MASK)) 250 boot->ClustMask = CLUST16_MASK; 251 else { 252 pfatal("Filesystem too big (%u clusters) for non-FAT32 partition", 253 boot->NumClusters); 254 return FSFATAL; 255 } 256 257 switch (boot->ClustMask) { 258 case CLUST32_MASK: 259 boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec) / 4; 260 break; 261 case CLUST16_MASK: 262 boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec) / 2; 263 break; 264 default: 265 boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec * 2) / 3; 266 break; 267 } 268 269 if (boot->NumFatEntries < boot->NumClusters) { 270 pfatal("FAT size too small, %u entries won't fit into %u sectors\n", 271 boot->NumClusters, boot->FATsecs); 272 return FSFATAL; 273 } 274 boot->ClusterSize = boot->BytesPerSec * boot->SecPerClust; 275 276 boot->NumFiles = 1; 277 boot->NumFree = 0; 278 279 return ret; 280 } 281 282 int 283 writefsinfo(dosfs, boot) 284 int dosfs; 285 struct bootblock *boot; 286 { 287 u_char fsinfo[2 * DOSBOOTBLOCKSIZE]; 288 289 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 290 != boot->FSInfo * boot->BytesPerSec 291 || read(dosfs, fsinfo, sizeof fsinfo) != sizeof fsinfo) { 292 perror("could not read fsinfo block"); 293 return FSFATAL; 294 } 295 fsinfo[0x1e8] = (u_char)boot->FSFree; 296 fsinfo[0x1e9] = (u_char)(boot->FSFree >> 8); 297 fsinfo[0x1ea] = (u_char)(boot->FSFree >> 16); 298 fsinfo[0x1eb] = (u_char)(boot->FSFree >> 24); 299 fsinfo[0x1ec] = (u_char)boot->FSNext; 300 fsinfo[0x1ed] = (u_char)(boot->FSNext >> 8); 301 fsinfo[0x1ee] = (u_char)(boot->FSNext >> 16); 302 fsinfo[0x1ef] = (u_char)(boot->FSNext >> 24); 303 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 304 != boot->FSInfo * boot->BytesPerSec 305 || write(dosfs, fsinfo, sizeof fsinfo) 306 != sizeof fsinfo) { 307 perror("Unable to write FSInfo"); 308 return FSFATAL; 309 } 310 /* 311 * Technically, we should return FSBOOTMOD here. 312 * 313 * However, since Win95 OSR2 (the first M$ OS that has 314 * support for FAT32) doesn't maintain the FSINFO block 315 * correctly, it has to be fixed pretty often. 316 * 317 * Therefor, we handle the FSINFO block only informally, 318 * fixing it if necessary, but otherwise ignoring the 319 * fact that it was incorrect. 320 */ 321 return 0; 322 } 323
