boot.c revision 203871
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 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR 15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 17 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, 18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 */ 25 26 27#include <sys/cdefs.h> 28#ifndef lint 29__RCSID("$NetBSD: boot.c,v 1.9 2003/07/24 19:25:46 ws Exp $"); 30static const char rcsid[] = 31 "$FreeBSD: head/sbin/fsck_msdosfs/boot.c 203871 2010-02-14 12:28:43Z kib $"; 32#endif /* not lint */ 33 34#include <stdlib.h> 35#include <string.h> 36#include <ctype.h> 37#include <stdio.h> 38#include <unistd.h> 39 40#include "ext.h" 41#include "fsutil.h" 42 43int 44readboot(dosfs, boot) 45 int dosfs; 46 struct bootblock *boot; 47{ 48 u_char block[DOSBOOTBLOCKSIZE]; 49 u_char fsinfo[2 * DOSBOOTBLOCKSIZE]; 50 u_char backup[DOSBOOTBLOCKSIZE]; 51 int ret = FSOK; 52 53 if (read(dosfs, block, sizeof block) < sizeof block) { 54 perror("could not read boot block"); 55 return FSFATAL; 56 } 57 58 if (block[510] != 0x55 || block[511] != 0xaa) { 59 pfatal("Invalid signature in boot block: %02x%02x", block[511], block[510]); 60 return FSFATAL; 61 } 62 63 memset(boot, 0, sizeof *boot); 64 boot->ValidFat = -1; 65 66 /* decode bios parameter block */ 67 boot->BytesPerSec = block[11] + (block[12] << 8); 68 boot->SecPerClust = block[13]; 69 boot->ResSectors = block[14] + (block[15] << 8); 70 boot->FATs = block[16]; 71 boot->RootDirEnts = block[17] + (block[18] << 8); 72 boot->Sectors = block[19] + (block[20] << 8); 73 boot->Media = block[21]; 74 boot->FATsmall = block[22] + (block[23] << 8); 75 boot->SecPerTrack = block[24] + (block[25] << 8); 76 boot->Heads = block[26] + (block[27] << 8); 77 boot->HiddenSecs = block[28] + (block[29] << 8) + (block[30] << 16) + (block[31] << 24); 78 boot->HugeSectors = block[32] + (block[33] << 8) + (block[34] << 16) + (block[35] << 24); 79 80 boot->FATsecs = boot->FATsmall; 81 82 if (!boot->RootDirEnts) 83 boot->flags |= FAT32; 84 if (boot->flags & FAT32) { 85 boot->FATsecs = block[36] + (block[37] << 8) 86 + (block[38] << 16) + (block[39] << 24); 87 if (block[40] & 0x80) 88 boot->ValidFat = block[40] & 0x0f; 89 90 /* check version number: */ 91 if (block[42] || block[43]) { 92 /* Correct? XXX */ 93 pfatal("Unknown file system version: %x.%x", 94 block[43], block[42]); 95 return FSFATAL; 96 } 97 boot->RootCl = block[44] + (block[45] << 8) 98 + (block[46] << 16) + (block[47] << 24); 99 boot->FSInfo = block[48] + (block[49] << 8); 100 boot->Backup = block[50] + (block[51] << 8); 101 102 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 103 != boot->FSInfo * boot->BytesPerSec 104 || read(dosfs, fsinfo, sizeof fsinfo) 105 != sizeof fsinfo) { 106 perror("could not read fsinfo block"); 107 return FSFATAL; 108 } 109 if (memcmp(fsinfo, "RRaA", 4) 110 || memcmp(fsinfo + 0x1e4, "rrAa", 4) 111 || fsinfo[0x1fc] 112 || fsinfo[0x1fd] 113 || fsinfo[0x1fe] != 0x55 114 || fsinfo[0x1ff] != 0xaa 115 || fsinfo[0x3fc] 116 || fsinfo[0x3fd] 117 || fsinfo[0x3fe] != 0x55 118 || fsinfo[0x3ff] != 0xaa) { 119 pwarn("Invalid signature in fsinfo block\n"); 120 if (ask(0, "Fix")) { 121 memcpy(fsinfo, "RRaA", 4); 122 memcpy(fsinfo + 0x1e4, "rrAa", 4); 123 fsinfo[0x1fc] = fsinfo[0x1fd] = 0; 124 fsinfo[0x1fe] = 0x55; 125 fsinfo[0x1ff] = 0xaa; 126 fsinfo[0x3fc] = fsinfo[0x3fd] = 0; 127 fsinfo[0x3fe] = 0x55; 128 fsinfo[0x3ff] = 0xaa; 129 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 130 != boot->FSInfo * boot->BytesPerSec 131 || write(dosfs, fsinfo, sizeof fsinfo) 132 != sizeof fsinfo) { 133 perror("Unable to write FSInfo"); 134 return FSFATAL; 135 } 136 ret = FSBOOTMOD; 137 } else 138 boot->FSInfo = 0; 139 } 140 if (boot->FSInfo) { 141 boot->FSFree = fsinfo[0x1e8] + (fsinfo[0x1e9] << 8) 142 + (fsinfo[0x1ea] << 16) 143 + (fsinfo[0x1eb] << 24); 144 boot->FSNext = fsinfo[0x1ec] + (fsinfo[0x1ed] << 8) 145 + (fsinfo[0x1ee] << 16) 146 + (fsinfo[0x1ef] << 24); 147 } 148 149 if (lseek(dosfs, boot->Backup * boot->BytesPerSec, SEEK_SET) 150 != boot->Backup * boot->BytesPerSec 151 || read(dosfs, backup, sizeof backup) != sizeof backup) { 152 perror("could not read backup bootblock"); 153 return FSFATAL; 154 } 155 backup[65] = block[65]; /* XXX */ 156 if (memcmp(block + 11, backup + 11, 79)) { 157 /* Correct? XXX */ 158 pfatal("backup doesn't compare to primary bootblock"); 159 if (alwaysno) 160 pfatal("\n"); 161 else 162 return FSFATAL; 163 } 164 /* Check backup FSInfo? XXX */ 165 } 166 167 boot->ClusterOffset = (boot->RootDirEnts * 32 + boot->BytesPerSec - 1) 168 / boot->BytesPerSec 169 + boot->ResSectors 170 + boot->FATs * boot->FATsecs 171 - CLUST_FIRST * boot->SecPerClust; 172 173 if (boot->BytesPerSec % DOSBOOTBLOCKSIZE != 0) { 174 pfatal("Invalid sector size: %u", boot->BytesPerSec); 175 return FSFATAL; 176 } 177 if (boot->SecPerClust == 0) { 178 pfatal("Invalid cluster size: %u", boot->SecPerClust); 179 return FSFATAL; 180 } 181 if (boot->Sectors) { 182 boot->HugeSectors = 0; 183 boot->NumSectors = boot->Sectors; 184 } else 185 boot->NumSectors = boot->HugeSectors; 186 boot->NumClusters = (boot->NumSectors - boot->ClusterOffset) / boot->SecPerClust; 187 188 if (boot->flags&FAT32) 189 boot->ClustMask = CLUST32_MASK; 190 else if (boot->NumClusters < (CLUST_RSRVD&CLUST12_MASK)) 191 boot->ClustMask = CLUST12_MASK; 192 else if (boot->NumClusters < (CLUST_RSRVD&CLUST16_MASK)) 193 boot->ClustMask = CLUST16_MASK; 194 else { 195 pfatal("Filesystem too big (%u clusters) for non-FAT32 partition", 196 boot->NumClusters); 197 return FSFATAL; 198 } 199 200 switch (boot->ClustMask) { 201 case CLUST32_MASK: 202 boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec) / 4; 203 break; 204 case CLUST16_MASK: 205 boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec) / 2; 206 break; 207 default: 208 boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec * 2) / 3; 209 break; 210 } 211 212 if (boot->NumFatEntries < boot->NumClusters) { 213 pfatal("FAT size too small, %u entries won't fit into %u sectors\n", 214 boot->NumClusters, boot->FATsecs); 215 return FSFATAL; 216 } 217 boot->ClusterSize = boot->BytesPerSec * boot->SecPerClust; 218 219 boot->NumFiles = 1; 220 boot->NumFree = 0; 221 222 return ret; 223} 224 225int 226writefsinfo(dosfs, boot) 227 int dosfs; 228 struct bootblock *boot; 229{ 230 u_char fsinfo[2 * DOSBOOTBLOCKSIZE]; 231 232 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 233 != boot->FSInfo * boot->BytesPerSec 234 || read(dosfs, fsinfo, sizeof fsinfo) != sizeof fsinfo) { 235 perror("could not read fsinfo block"); 236 return FSFATAL; 237 } 238 fsinfo[0x1e8] = (u_char)boot->FSFree; 239 fsinfo[0x1e9] = (u_char)(boot->FSFree >> 8); 240 fsinfo[0x1ea] = (u_char)(boot->FSFree >> 16); 241 fsinfo[0x1eb] = (u_char)(boot->FSFree >> 24); 242 fsinfo[0x1ec] = (u_char)boot->FSNext; 243 fsinfo[0x1ed] = (u_char)(boot->FSNext >> 8); 244 fsinfo[0x1ee] = (u_char)(boot->FSNext >> 16); 245 fsinfo[0x1ef] = (u_char)(boot->FSNext >> 24); 246 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 247 != boot->FSInfo * boot->BytesPerSec 248 || write(dosfs, fsinfo, sizeof fsinfo) 249 != sizeof fsinfo) { 250 perror("Unable to write FSInfo"); 251 return FSFATAL; 252 } 253 /* 254 * Technically, we should return FSBOOTMOD here. 255 * 256 * However, since Win95 OSR2 (the first M$ OS that has 257 * support for FAT32) doesn't maintain the FSINFO block 258 * correctly, it has to be fixed pretty often. 259 * 260 * Therefor, we handle the FSINFO block only informally, 261 * fixing it if necessary, but otherwise ignoring the 262 * fact that it was incorrect. 263 */ 264 return 0; 265} 266