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 * $NetBSD: boot.c,v 1.5 1997/10/17 11:19:23 ws Exp $ 33 * $FreeBSD: src/sbin/fsck_msdosfs/boot.c,v 1.1.2.1 2001/08/01 05:47:55 obrien Exp $ 34 * $DragonFly: src/sbin/fsck_msdosfs/boot.c,v 1.3 2003/09/28 14:39:17 hmp Exp $ 35 */ 36 37 38 #include <sys/cdefs.h> 39 40 #include <stdlib.h> 41 #include <string.h> 42 #include <ctype.h> 43 #include <stdio.h> 44 #include <unistd.h> 45 46 #include "ext.h" 47 #include "fsutil.h" 48 49 int 50 readboot(int dosfs, struct bootblock *boot) 51 { 52 u_char block[DOSBOOTBLOCKSIZE]; 53 u_char fsinfo[2 * DOSBOOTBLOCKSIZE]; 54 u_char backup[DOSBOOTBLOCKSIZE]; 55 int ret = FSOK; 56 57 if (read(dosfs, block, sizeof block) < sizeof block) { 58 perror("could not read boot block"); 59 return FSFATAL; 60 } 61 62 if (block[510] != 0x55 || block[511] != 0xaa) { 63 pfatal("Invalid signature in boot block: %02x%02x", block[511], block[510]); 64 return FSFATAL; 65 } 66 67 memset(boot, 0, sizeof *boot); 68 boot->ValidFat = -1; 69 70 /* decode bios parameter block */ 71 boot->BytesPerSec = block[11] + (block[12] << 8); 72 boot->SecPerClust = block[13]; 73 boot->ResSectors = block[14] + (block[15] << 8); 74 boot->FATs = block[16]; 75 boot->RootDirEnts = block[17] + (block[18] << 8); 76 boot->Sectors = block[19] + (block[20] << 8); 77 boot->Media = block[21]; 78 boot->FATsmall = block[22] + (block[23] << 8); 79 boot->SecPerTrack = block[24] + (block[25] << 8); 80 boot->Heads = block[26] + (block[27] << 8); 81 boot->HiddenSecs = block[28] + (block[29] << 8) + (block[30] << 16) + (block[31] << 24); 82 boot->HugeSectors = block[32] + (block[33] << 8) + (block[34] << 16) + (block[35] << 24); 83 84 boot->FATsecs = boot->FATsmall; 85 86 if (!boot->RootDirEnts) 87 boot->flags |= FAT32; 88 if (boot->flags & FAT32) { 89 boot->FATsecs = block[36] + (block[37] << 8) 90 + (block[38] << 16) + (block[39] << 24); 91 if (block[40] & 0x80) 92 boot->ValidFat = block[40] & 0x0f; 93 94 /* check version number: */ 95 if (block[42] || block[43]) { 96 /* Correct? XXX */ 97 pfatal("Unknown filesystem version: %x.%x", 98 block[43], block[42]); 99 return FSFATAL; 100 } 101 boot->RootCl = block[44] + (block[45] << 8) 102 + (block[46] << 16) + (block[47] << 24); 103 boot->FSInfo = block[48] + (block[49] << 8); 104 boot->Backup = block[50] + (block[51] << 8); 105 106 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 107 != boot->FSInfo * boot->BytesPerSec 108 || read(dosfs, fsinfo, sizeof fsinfo) 109 != sizeof fsinfo) { 110 perror("could not read fsinfo block"); 111 return FSFATAL; 112 } 113 if (memcmp(fsinfo, "RRaA", 4) 114 || memcmp(fsinfo + 0x1e4, "rrAa", 4) 115 || fsinfo[0x1fc] 116 || fsinfo[0x1fd] 117 || fsinfo[0x1fe] != 0x55 118 || fsinfo[0x1ff] != 0xaa 119 || fsinfo[0x3fc] 120 || fsinfo[0x3fd] 121 || fsinfo[0x3fe] != 0x55 122 || fsinfo[0x3ff] != 0xaa) { 123 pwarn("Invalid signature in fsinfo block"); 124 if (ask(0, "fix")) { 125 memcpy(fsinfo, "RRaA", 4); 126 memcpy(fsinfo + 0x1e4, "rrAa", 4); 127 fsinfo[0x1fc] = fsinfo[0x1fd] = 0; 128 fsinfo[0x1fe] = 0x55; 129 fsinfo[0x1ff] = 0xaa; 130 fsinfo[0x3fc] = fsinfo[0x3fd] = 0; 131 fsinfo[0x3fe] = 0x55; 132 fsinfo[0x3ff] = 0xaa; 133 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 134 != boot->FSInfo * boot->BytesPerSec 135 || write(dosfs, fsinfo, sizeof fsinfo) 136 != sizeof fsinfo) { 137 perror("Unable to write FSInfo"); 138 return FSFATAL; 139 } 140 ret = FSBOOTMOD; 141 } else 142 boot->FSInfo = 0; 143 } 144 if (boot->FSInfo) { 145 boot->FSFree = fsinfo[0x1e8] + (fsinfo[0x1e9] << 8) 146 + (fsinfo[0x1ea] << 16) 147 + (fsinfo[0x1eb] << 24); 148 boot->FSNext = fsinfo[0x1ec] + (fsinfo[0x1ed] << 8) 149 + (fsinfo[0x1ee] << 16) 150 + (fsinfo[0x1ef] << 24); 151 } 152 153 if (lseek(dosfs, boot->Backup * boot->BytesPerSec, SEEK_SET) 154 != boot->Backup * boot->BytesPerSec 155 || read(dosfs, backup, sizeof backup) != sizeof backup) { 156 perror("could not read backup bootblock"); 157 return FSFATAL; 158 } 159 if (memcmp(block, backup, DOSBOOTBLOCKSIZE)) { 160 /* Correct? XXX */ 161 pfatal("backup doesn't compare to primary bootblock"); 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 } 224 225 int 226 writefsinfo(int dosfs, struct bootblock *boot) 227 { 228 u_char fsinfo[2 * DOSBOOTBLOCKSIZE]; 229 230 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 231 != boot->FSInfo * boot->BytesPerSec 232 || read(dosfs, fsinfo, sizeof fsinfo) != sizeof fsinfo) { 233 perror("could not read fsinfo block"); 234 return FSFATAL; 235 } 236 fsinfo[0x1e8] = (u_char)boot->FSFree; 237 fsinfo[0x1e9] = (u_char)(boot->FSFree >> 8); 238 fsinfo[0x1ea] = (u_char)(boot->FSFree >> 16); 239 fsinfo[0x1eb] = (u_char)(boot->FSFree >> 24); 240 fsinfo[0x1ec] = (u_char)boot->FSNext; 241 fsinfo[0x1ed] = (u_char)(boot->FSNext >> 8); 242 fsinfo[0x1ee] = (u_char)(boot->FSNext >> 16); 243 fsinfo[0x1ef] = (u_char)(boot->FSNext >> 24); 244 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 245 != boot->FSInfo * boot->BytesPerSec 246 || write(dosfs, fsinfo, sizeof fsinfo) 247 != sizeof fsinfo) { 248 perror("Unable to write FSInfo"); 249 return FSFATAL; 250 } 251 /* 252 * Technically, we should return FSBOOTMOD here. 253 * 254 * However, since Win95 OSR2 (the first M$ OS that has 255 * support for FAT32) doesn't maintain the FSINFO block 256 * correctly, it has to be fixed pretty often. 257 * 258 * Therefor, we handle the FSINFO block only informally, 259 * fixing it if neccessary, but otherwise ignoring the 260 * fact that it was incorrect. 261 */ 262 return 0; 263 } 264