1 /* $OpenBSD: boot.c,v 1.6 2001/07/03 13:03:44 ian Exp $ */ 2 /* $NetBSD: boot.c,v 1.5 1997/10/17 11:19:23 ws Exp $ */ 3 4 /* 5 * Copyright (C) 1995, 1997 Wolfgang Solfrank 6 * Copyright (c) 1995 Martin Husemann 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by Martin Husemann 19 * and Wolfgang Solfrank. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR 25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 27 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, 28 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 29 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 30 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 33 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34 */ 35 36 37 #ifndef lint 38 static char rcsid[] = "$OpenBSD: boot.c,v 1.6 2001/07/03 13:03:44 ian 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 49 int 50 readboot(dosfs, boot) 51 int dosfs; 52 struct bootblock *boot; 53 { 54 u_char block[DOSBOOTBLOCKSIZE]; 55 u_char fsinfo[2 * DOSBOOTBLOCKSIZE]; 56 u_char backup[DOSBOOTBLOCKSIZE]; 57 int ret = FSOK; 58 59 if (read(dosfs, block, sizeof block) < sizeof block) { 60 perror("could not read boot block"); 61 return (FSFATAL); 62 } 63 64 if (block[510] != 0x55 || block[511] != 0xaa) { 65 pfatal("Invalid signature in boot block: %02x%02x\n", block[511], block[510]); 66 return FSFATAL; 67 } 68 69 memset(boot, 0, sizeof *boot); 70 boot->ValidFat = -1; 71 72 /* decode bios parameter block */ 73 boot->BytesPerSec = block[11] + (block[12] << 8); 74 boot->SecPerClust = block[13]; 75 boot->ResSectors = block[14] + (block[15] << 8); 76 boot->FATs = block[16]; 77 boot->RootDirEnts = block[17] + (block[18] << 8); 78 boot->Sectors = block[19] + (block[20] << 8); 79 boot->Media = block[21]; 80 boot->FATsmall = block[22] + (block[23] << 8); 81 boot->SecPerTrack = block[24] + (block[25] << 8); 82 boot->Heads = block[26] + (block[27] << 8); 83 boot->HiddenSecs = block[28] + (block[29] << 8) + (block[30] << 16) + (block[31] << 24); 84 boot->HugeSectors = block[32] + (block[33] << 8) + (block[34] << 16) + (block[35] << 24); 85 86 boot->FATsecs = boot->FATsmall; 87 88 if (!boot->RootDirEnts) 89 boot->flags |= FAT32; 90 if (boot->flags & FAT32) { 91 boot->FATsecs = block[36] + (block[37] << 8) 92 + (block[38] << 16) + (block[39] << 24); 93 if (block[40] & 0x80) 94 boot->ValidFat = block[40] & 0x0f; 95 96 /* check version number: */ 97 if (block[42] || block[43]) { 98 /* Correct? XXX */ 99 pfatal("Unknown filesystem version: %x.%x\n", 100 block[43], block[42]); 101 return FSFATAL; 102 } 103 boot->RootCl = block[44] + (block[45] << 8) 104 + (block[46] << 16) + (block[47] << 24); 105 boot->FSInfo = block[48] + (block[49] << 8); 106 boot->Backup = block[50] + (block[51] << 8); 107 108 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 109 != boot->FSInfo * boot->BytesPerSec 110 || read(dosfs, fsinfo, sizeof fsinfo) 111 != sizeof fsinfo) { 112 perror("could not read fsinfo block"); 113 return FSFATAL; 114 } 115 if (memcmp(fsinfo, "RRaA", 4) 116 || memcmp(fsinfo + 0x1e4, "rrAa", 4) 117 || fsinfo[0x1fc] 118 || fsinfo[0x1fd] 119 || fsinfo[0x1fe] != 0x55 120 || fsinfo[0x1ff] != 0xaa 121 || fsinfo[0x3fc] 122 || fsinfo[0x3fd] 123 || fsinfo[0x3fe] != 0x55 124 || fsinfo[0x3ff] != 0xaa) { 125 pwarn("Invalid signature in fsinfo block"); 126 if (ask(0, "fix")) { 127 memcpy(fsinfo, "RRaA", 4); 128 memcpy(fsinfo + 0x1e4, "rrAa", 4); 129 fsinfo[0x1fc] = fsinfo[0x1fd] = 0; 130 fsinfo[0x1fe] = 0x55; 131 fsinfo[0x1ff] = 0xaa; 132 fsinfo[0x3fc] = fsinfo[0x3fd] = 0; 133 fsinfo[0x3fe] = 0x55; 134 fsinfo[0x3ff] = 0xaa; 135 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 136 != boot->FSInfo * boot->BytesPerSec 137 || write(dosfs, fsinfo, sizeof fsinfo) 138 != sizeof fsinfo) { 139 perror("Unable to write FSInfo"); 140 return FSFATAL; 141 } 142 ret = FSBOOTMOD; 143 } else 144 boot->FSInfo = 0; 145 } 146 if (boot->FSInfo) { 147 boot->FSFree = fsinfo[0x1e8] + (fsinfo[0x1e9] << 8) 148 + (fsinfo[0x1ea] << 16) 149 + (fsinfo[0x1eb] << 24); 150 boot->FSNext = fsinfo[0x1ec] + (fsinfo[0x1ed] << 8) 151 + (fsinfo[0x1ee] << 16) 152 + (fsinfo[0x1ef] << 24); 153 } 154 155 if (lseek(dosfs, boot->Backup * boot->BytesPerSec, SEEK_SET) 156 != boot->Backup * boot->BytesPerSec 157 || read(dosfs, backup, sizeof backup) != sizeof backup) { 158 perror("could not read backup bootblock"); 159 return FSFATAL; 160 } 161 if (memcmp(block, backup, DOSBOOTBLOCKSIZE)) { 162 /* Correct? XXX */ 163 pfatal("backup doesn't compare to primary bootblock\n"); 164 return FSFATAL; 165 } 166 /* Check backup FSInfo? XXX */ 167 } 168 169 boot->ClusterOffset = (boot->RootDirEnts * 32 + boot->BytesPerSec - 1) 170 / boot->BytesPerSec 171 + boot->ResSectors 172 + boot->FATs * boot->FATsecs 173 - CLUST_FIRST * boot->SecPerClust; 174 175 if (boot->BytesPerSec % DOSBOOTBLOCKSIZE != 0) { 176 pfatal("Invalid sector size: %u\n", boot->BytesPerSec); 177 return (FSFATAL); 178 } 179 if (boot->SecPerClust == 0) { 180 pfatal("Invalid cluster size: %u\n", boot->SecPerClust); 181 return (FSFATAL); 182 } 183 if (boot->Sectors) { 184 boot->HugeSectors = 0; 185 boot->NumSectors = boot->Sectors; 186 } else 187 boot->NumSectors = boot->HugeSectors; 188 boot->NumClusters = (boot->NumSectors - boot->ClusterOffset) / boot->SecPerClust; 189 190 if (boot->flags&FAT32) 191 boot->ClustMask = CLUST32_MASK; 192 else if (boot->NumClusters < (CLUST_RSRVD&CLUST12_MASK)) 193 boot->ClustMask = CLUST12_MASK; 194 else if (boot->NumClusters < (CLUST_RSRVD&CLUST16_MASK)) 195 boot->ClustMask = CLUST16_MASK; 196 else { 197 pfatal("Filesystem too big (%u clusters) for non-FAT32 partition\n", 198 boot->NumClusters); 199 return FSFATAL; 200 } 201 202 switch (boot->ClustMask) { 203 case CLUST32_MASK: 204 boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec) / 4; 205 break; 206 case CLUST16_MASK: 207 boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec) / 2; 208 break; 209 default: 210 boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec * 2) / 3; 211 break; 212 } 213 214 if (boot->NumFatEntries < boot->NumClusters) { 215 pfatal("FAT size too small, %u entries won't fit into %u sectors\n", 216 boot->NumClusters, boot->FATsecs); 217 return (FSFATAL); 218 } 219 boot->ClusterSize = boot->BytesPerSec * boot->SecPerClust; 220 221 boot->NumFiles = 1; 222 boot->NumFree = 0; 223 224 return ret; 225 } 226 227 int 228 writefsinfo(dosfs, boot) 229 int dosfs; 230 struct bootblock *boot; 231 { 232 u_char fsinfo[2 * DOSBOOTBLOCKSIZE]; 233 234 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 235 != boot->FSInfo * boot->BytesPerSec 236 || read(dosfs, fsinfo, sizeof fsinfo) != sizeof fsinfo) { 237 perror("could not read fsinfo block"); 238 return FSFATAL; 239 } 240 fsinfo[0x1e8] = (u_char)boot->FSFree; 241 fsinfo[0x1e9] = (u_char)(boot->FSFree >> 8); 242 fsinfo[0x1ea] = (u_char)(boot->FSFree >> 16); 243 fsinfo[0x1eb] = (u_char)(boot->FSFree >> 24); 244 fsinfo[0x1ec] = (u_char)boot->FSNext; 245 fsinfo[0x1ed] = (u_char)(boot->FSNext >> 8); 246 fsinfo[0x1ee] = (u_char)(boot->FSNext >> 16); 247 fsinfo[0x1ef] = (u_char)(boot->FSNext >> 24); 248 if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) 249 != boot->FSInfo * boot->BytesPerSec 250 || write(dosfs, fsinfo, sizeof fsinfo) 251 != sizeof fsinfo) { 252 perror("Unable to write FSInfo"); 253 return FSFATAL; 254 } 255 /* 256 * Technically, we should return FSBOOTMOD here. 257 * 258 * However, since Win95 OSR2 (the first M$ OS that has 259 * support for FAT32) doesn't maintain the FSINFO block 260 * correctly, it has to be fixed pretty often. 261 * 262 * Therefor, we handle the FSINFO block only informally, 263 * fixing it if neccessary, but otherwise ignoring the 264 * fact that it was incorrect. 265 */ 266 return 0; 267 } 268