boot.c revision 128463
1169691Skan/* 297403Sobrien * Copyright (C) 1995, 1997 Wolfgang Solfrank 397403Sobrien * Copyright (c) 1995 Martin Husemann 497403Sobrien * 597403Sobrien * Redistribution and use in source and binary forms, with or without 697403Sobrien * modification, are permitted provided that the following conditions 797403Sobrien * are met: 897403Sobrien * 1. Redistributions of source code must retain the above copyright 997403Sobrien * notice, this list of conditions and the following disclaimer. 1097403Sobrien * 2. Redistributions in binary form must reproduce the above copyright 1197403Sobrien * notice, this list of conditions and the following disclaimer in the 1297403Sobrien * documentation and/or other materials provided with the distribution. 1397403Sobrien * 3. All advertising materials mentioning features or use of this software 1497403Sobrien * must display the following acknowledgement: 1597403Sobrien * This product includes software developed by Martin Husemann 16169691Skan * and Wolfgang Solfrank. 1797403Sobrien * 4. Neither the name of the University nor the names of its contributors 1897403Sobrien * may be used to endorse or promote products derived from this software 1997403Sobrien * without specific prior written permission. 2097403Sobrien * 2197403Sobrien * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR 2297403Sobrien * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 2397403Sobrien * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 2497403Sobrien * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, 2597403Sobrien * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 2697403Sobrien * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 2797403Sobrien * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28169691Skan * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 2997403Sobrien * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 3097403Sobrien * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 3197403Sobrien */ 32169691Skan 33169691Skan 34103447Skan#include <sys/cdefs.h> 35103447Skan#ifndef lint 36103447Skan__RCSID("$NetBSD: boot.c,v 1.9 2003/07/24 19:25:46 ws Exp $"); 37132720Skanstatic const char rcsid[] = 38103447Skan "$FreeBSD: head/sbin/fsck_msdosfs/boot.c 128463 2004-04-20 11:41:57Z tjr $"; 39103447Skan#endif /* not lint */ 40103447Skan 4197403Sobrien#include <stdlib.h> 4297403Sobrien#include <string.h> 43132720Skan#include <ctype.h> 44132720Skan#include <stdio.h> 4597403Sobrien#include <unistd.h> 4697403Sobrien 4797403Sobrien#include "ext.h" 48132720Skan#include "fsutil.h" 49132720Skan 50132720Skanint 51132720Skanreadboot(dosfs, boot) 52132720Skan int dosfs; 53132720Skan struct bootblock *boot; 54103447Skan{ 55132720Skan u_char block[DOSBOOTBLOCKSIZE]; 5697403Sobrien u_char fsinfo[2 * DOSBOOTBLOCKSIZE]; 5797403Sobrien u_char backup[DOSBOOTBLOCKSIZE]; 5897403Sobrien int ret = FSOK; 5997403Sobrien 60110614Skan if (read(dosfs, block, sizeof block) < sizeof block) { 61110614Skan perror("could not read boot block"); 6297403Sobrien return FSFATAL; 6397403Sobrien } 64132720Skan 65110614Skan if (block[510] != 0x55 || block[511] != 0xaa) { 66110614Skan pfatal("Invalid signature in boot block: %02x%02x", block[511], block[510]); 6797403Sobrien return FSFATAL; 6897403Sobrien } 6997403Sobrien 7097403Sobrien memset(boot, 0, sizeof *boot); 7197403Sobrien boot->ValidFat = -1; 7297403Sobrien 7397403Sobrien /* decode bios parameter block */ 7497403Sobrien boot->BytesPerSec = block[11] + (block[12] << 8); 7597403Sobrien boot->SecPerClust = block[13]; 7697403Sobrien boot->ResSectors = block[14] + (block[15] << 8); 7797403Sobrien boot->FATs = block[16]; 7897403Sobrien boot->RootDirEnts = block[17] + (block[18] << 8); 7997403Sobrien boot->Sectors = block[19] + (block[20] << 8); 8097403Sobrien boot->Media = block[21]; 8197403Sobrien boot->FATsmall = block[22] + (block[23] << 8); 8297403Sobrien boot->SecPerTrack = block[24] + (block[25] << 8); 8397403Sobrien boot->Heads = block[26] + (block[27] << 8); 84110614Skan boot->HiddenSecs = block[28] + (block[29] << 8) + (block[30] << 16) + (block[31] << 24); 85132720Skan boot->HugeSectors = block[32] + (block[33] << 8) + (block[34] << 16) + (block[35] << 24); 86117397Skan 87132720Skan boot->FATsecs = boot->FATsmall; 88110614Skan 89110614Skan if (!boot->RootDirEnts) 9097403Sobrien boot->flags |= FAT32; 9197403Sobrien if (boot->flags & FAT32) { 9297403Sobrien boot->FATsecs = block[36] + (block[37] << 8) 9397403Sobrien + (block[38] << 16) + (block[39] << 24); 9497403Sobrien if (block[40] & 0x80) 9597403Sobrien boot->ValidFat = block[40] & 0x0f; 9697403Sobrien 9797403Sobrien /* check version number: */ 9897403Sobrien if (block[42] || block[43]) { 9997403Sobrien /* Correct? XXX */ 10097403Sobrien pfatal("Unknown file system version: %x.%x", 10197403Sobrien block[43], block[42]); 10297403Sobrien return FSFATAL; 10397403Sobrien } 10497403Sobrien boot->RootCl = block[44] + (block[45] << 8) 10597403Sobrien + (block[46] << 16) + (block[47] << 24); 10697403Sobrien boot->FSInfo = block[48] + (block[49] << 8); 107132720Skan boot->Backup = block[50] + (block[51] << 8); 10897403Sobrien 109132720Skan if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 110132720Skan != boot->FSInfo * boot->BytesPerSec 111132720Skan || read(dosfs, fsinfo, sizeof fsinfo) 112132720Skan != sizeof fsinfo) { 11397403Sobrien perror("could not read fsinfo block"); 11497403Sobrien return FSFATAL; 11597403Sobrien } 11697403Sobrien if (memcmp(fsinfo, "RRaA", 4) 11797403Sobrien || memcmp(fsinfo + 0x1e4, "rrAa", 4) 11897403Sobrien || fsinfo[0x1fc] 119132720Skan || fsinfo[0x1fd] 12097403Sobrien || fsinfo[0x1fe] != 0x55 12197403Sobrien || fsinfo[0x1ff] != 0xaa 12297403Sobrien || fsinfo[0x3fc] 123132720Skan || fsinfo[0x3fd] 124132720Skan || fsinfo[0x3fe] != 0x55 125103447Skan || fsinfo[0x3ff] != 0xaa) { 12697403Sobrien pwarn("Invalid signature in fsinfo block"); 12797403Sobrien if (ask(0, "fix")) { 128132720Skan memcpy(fsinfo, "RRaA", 4); 129132720Skan memcpy(fsinfo + 0x1e4, "rrAa", 4); 130132720Skan fsinfo[0x1fc] = fsinfo[0x1fd] = 0; 131132720Skan fsinfo[0x1fe] = 0x55; 132132720Skan fsinfo[0x1ff] = 0xaa; 133132720Skan fsinfo[0x3fc] = fsinfo[0x3fd] = 0; 134103447Skan fsinfo[0x3fe] = 0x55; 135132720Skan fsinfo[0x3ff] = 0xaa; 13697403Sobrien if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 13797403Sobrien != boot->FSInfo * boot->BytesPerSec 13897403Sobrien || write(dosfs, fsinfo, sizeof fsinfo) 13997403Sobrien != sizeof fsinfo) { 14097403Sobrien perror("Unable to write FSInfo"); 14197403Sobrien return FSFATAL; 142132720Skan } 14397403Sobrien ret = FSBOOTMOD; 14497403Sobrien } else 14597403Sobrien boot->FSInfo = 0; 14697403Sobrien } 14797403Sobrien if (boot->FSInfo) { 14897403Sobrien boot->FSFree = fsinfo[0x1e8] + (fsinfo[0x1e9] << 8) 14997403Sobrien + (fsinfo[0x1ea] << 16) 15097403Sobrien + (fsinfo[0x1eb] << 24); 151132720Skan boot->FSNext = fsinfo[0x1ec] + (fsinfo[0x1ed] << 8) 152169691Skan + (fsinfo[0x1ee] << 16) 153169691Skan + (fsinfo[0x1ef] << 24); 154 } 155 156 if (lseek(dosfs, boot->Backup * boot->BytesPerSec, SEEK_SET) 157 != boot->Backup * boot->BytesPerSec 158 || read(dosfs, backup, sizeof backup) != sizeof backup) { 159 perror("could not read backup bootblock"); 160 return FSFATAL; 161 } 162 backup[65] = block[65]; /* XXX */ 163 if (memcmp(block + 11, backup + 11, 79)) { 164 /* Correct? XXX */ 165 pfatal("backup doesn't compare to primary bootblock"); 166 if (alwaysno) 167 pfatal("\n"); 168 else 169 return FSFATAL; 170 } 171 /* Check backup FSInfo? XXX */ 172 } 173 174 boot->ClusterOffset = (boot->RootDirEnts * 32 + boot->BytesPerSec - 1) 175 / boot->BytesPerSec 176 + boot->ResSectors 177 + boot->FATs * boot->FATsecs 178 - CLUST_FIRST * boot->SecPerClust; 179 180 if (boot->BytesPerSec % DOSBOOTBLOCKSIZE != 0) { 181 pfatal("Invalid sector size: %u", boot->BytesPerSec); 182 return FSFATAL; 183 } 184 if (boot->SecPerClust == 0) { 185 pfatal("Invalid cluster size: %u", boot->SecPerClust); 186 return FSFATAL; 187 } 188 if (boot->Sectors) { 189 boot->HugeSectors = 0; 190 boot->NumSectors = boot->Sectors; 191 } else 192 boot->NumSectors = boot->HugeSectors; 193 boot->NumClusters = (boot->NumSectors - boot->ClusterOffset) / boot->SecPerClust; 194 195 if (boot->flags&FAT32) 196 boot->ClustMask = CLUST32_MASK; 197 else if (boot->NumClusters < (CLUST_RSRVD&CLUST12_MASK)) 198 boot->ClustMask = CLUST12_MASK; 199 else if (boot->NumClusters < (CLUST_RSRVD&CLUST16_MASK)) 200 boot->ClustMask = CLUST16_MASK; 201 else { 202 pfatal("Filesystem too big (%u clusters) for non-FAT32 partition", 203 boot->NumClusters); 204 return FSFATAL; 205 } 206 207 switch (boot->ClustMask) { 208 case CLUST32_MASK: 209 boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec) / 4; 210 break; 211 case CLUST16_MASK: 212 boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec) / 2; 213 break; 214 default: 215 boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec * 2) / 3; 216 break; 217 } 218 219 if (boot->NumFatEntries < boot->NumClusters) { 220 pfatal("FAT size too small, %u entries won't fit into %u sectors\n", 221 boot->NumClusters, boot->FATsecs); 222 return FSFATAL; 223 } 224 boot->ClusterSize = boot->BytesPerSec * boot->SecPerClust; 225 226 boot->NumFiles = 1; 227 boot->NumFree = 0; 228 229 return ret; 230} 231 232int 233writefsinfo(dosfs, boot) 234 int dosfs; 235 struct bootblock *boot; 236{ 237 u_char fsinfo[2 * DOSBOOTBLOCKSIZE]; 238 239 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 240 != boot->FSInfo * boot->BytesPerSec 241 || read(dosfs, fsinfo, sizeof fsinfo) != sizeof fsinfo) { 242 perror("could not read fsinfo block"); 243 return FSFATAL; 244 } 245 fsinfo[0x1e8] = (u_char)boot->FSFree; 246 fsinfo[0x1e9] = (u_char)(boot->FSFree >> 8); 247 fsinfo[0x1ea] = (u_char)(boot->FSFree >> 16); 248 fsinfo[0x1eb] = (u_char)(boot->FSFree >> 24); 249 fsinfo[0x1ec] = (u_char)boot->FSNext; 250 fsinfo[0x1ed] = (u_char)(boot->FSNext >> 8); 251 fsinfo[0x1ee] = (u_char)(boot->FSNext >> 16); 252 fsinfo[0x1ef] = (u_char)(boot->FSNext >> 24); 253 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 254 != boot->FSInfo * boot->BytesPerSec 255 || write(dosfs, fsinfo, sizeof fsinfo) 256 != sizeof fsinfo) { 257 perror("Unable to write FSInfo"); 258 return FSFATAL; 259 } 260 /* 261 * Technically, we should return FSBOOTMOD here. 262 * 263 * However, since Win95 OSR2 (the first M$ OS that has 264 * support for FAT32) doesn't maintain the FSINFO block 265 * correctly, it has to be fixed pretty often. 266 * 267 * Therefor, we handle the FSINFO block only informally, 268 * fixing it if necessary, but otherwise ignoring the 269 * fact that it was incorrect. 270 */ 271 return 0; 272} 273