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 $"); 30 static const char rcsid[] = 31 "$FreeBSD$"; 32 #endif /* not lint */ 33 34 #include <stdlib.h> 35 #include <string.h> 36 #include <stdio.h> 37 #include <unistd.h> 38 39 #include "ext.h" 40 #include "fsutil.h" 41 42 int 43 readboot(int dosfs, struct bootblock *boot) 44 { 45 u_char block[DOSBOOTBLOCKSIZE]; 46 u_char fsinfo[2 * DOSBOOTBLOCKSIZE]; 47 u_char backup[DOSBOOTBLOCKSIZE]; 48 int ret = FSOK; 49 int i; 50 51 if ((size_t)read(dosfs, block, sizeof block) != sizeof block) { 52 perror("could not read boot block"); 53 return FSFATAL; 54 } 55 56 if (block[510] != 0x55 || block[511] != 0xaa) { 57 pfatal("Invalid signature in boot block: %02x%02x", block[511], block[510]); 58 return FSFATAL; 59 } 60 61 memset(boot, 0, sizeof *boot); 62 boot->ValidFat = -1; 63 64 /* decode bios parameter block */ 65 boot->bpbBytesPerSec = block[11] + (block[12] << 8); 66 boot->bpbSecPerClust = block[13]; 67 boot->bpbResSectors = block[14] + (block[15] << 8); 68 boot->bpbFATs = block[16]; 69 boot->bpbRootDirEnts = block[17] + (block[18] << 8); 70 boot->bpbSectors = block[19] + (block[20] << 8); 71 boot->bpbMedia = block[21]; 72 boot->bpbFATsmall = block[22] + (block[23] << 8); 73 boot->SecPerTrack = block[24] + (block[25] << 8); 74 boot->bpbHeads = block[26] + (block[27] << 8); 75 boot->bpbHiddenSecs = block[28] + (block[29] << 8) + (block[30] << 16) + (block[31] << 24); 76 boot->bpbHugeSectors = block[32] + (block[33] << 8) + (block[34] << 16) + (block[35] << 24); 77 78 boot->FATsecs = boot->bpbFATsmall; 79 80 if (!boot->bpbRootDirEnts) 81 boot->flags |= FAT32; 82 if (boot->flags & FAT32) { 83 boot->FATsecs = block[36] + (block[37] << 8) 84 + (block[38] << 16) + (block[39] << 24); 85 if (block[40] & 0x80) 86 boot->ValidFat = block[40] & 0x0f; 87 88 /* check version number: */ 89 if (block[42] || block[43]) { 90 /* Correct? XXX */ 91 pfatal("Unknown file system version: %x.%x", 92 block[43], block[42]); 93 return FSFATAL; 94 } 95 boot->bpbRootClust = block[44] + (block[45] << 8) 96 + (block[46] << 16) + (block[47] << 24); 97 boot->bpbFSInfo = block[48] + (block[49] << 8); 98 boot->bpbBackup = block[50] + (block[51] << 8); 99 100 if (lseek(dosfs, boot->bpbFSInfo * boot->bpbBytesPerSec, SEEK_SET) 101 != boot->bpbFSInfo * boot->bpbBytesPerSec 102 || read(dosfs, fsinfo, sizeof fsinfo) 103 != sizeof fsinfo) { 104 perror("could not read fsinfo block"); 105 return FSFATAL; 106 } 107 if (memcmp(fsinfo, "RRaA", 4) 108 || memcmp(fsinfo + 0x1e4, "rrAa", 4) 109 || fsinfo[0x1fc] 110 || fsinfo[0x1fd] 111 || fsinfo[0x1fe] != 0x55 112 || fsinfo[0x1ff] != 0xaa 113 || fsinfo[0x3fc] 114 || fsinfo[0x3fd] 115 || fsinfo[0x3fe] != 0x55 116 || fsinfo[0x3ff] != 0xaa) { 117 pwarn("Invalid signature in fsinfo block\n"); 118 if (ask(0, "Fix")) { 119 memcpy(fsinfo, "RRaA", 4); 120 memcpy(fsinfo + 0x1e4, "rrAa", 4); 121 fsinfo[0x1fc] = fsinfo[0x1fd] = 0; 122 fsinfo[0x1fe] = 0x55; 123 fsinfo[0x1ff] = 0xaa; 124 fsinfo[0x3fc] = fsinfo[0x3fd] = 0; 125 fsinfo[0x3fe] = 0x55; 126 fsinfo[0x3ff] = 0xaa; 127 if (lseek(dosfs, boot->bpbFSInfo * boot->bpbBytesPerSec, SEEK_SET) 128 != boot->bpbFSInfo * boot->bpbBytesPerSec 129 || write(dosfs, fsinfo, sizeof fsinfo) 130 != sizeof fsinfo) { 131 perror("Unable to write bpbFSInfo"); 132 return FSFATAL; 133 } 134 ret = FSBOOTMOD; 135 } else 136 boot->bpbFSInfo = 0; 137 } 138 if (boot->bpbFSInfo) { 139 boot->FSFree = fsinfo[0x1e8] + (fsinfo[0x1e9] << 8) 140 + (fsinfo[0x1ea] << 16) 141 + (fsinfo[0x1eb] << 24); 142 boot->FSNext = fsinfo[0x1ec] + (fsinfo[0x1ed] << 8) 143 + (fsinfo[0x1ee] << 16) 144 + (fsinfo[0x1ef] << 24); 145 } 146 147 if (lseek(dosfs, boot->bpbBackup * boot->bpbBytesPerSec, SEEK_SET) 148 != boot->bpbBackup * boot->bpbBytesPerSec 149 || read(dosfs, backup, sizeof backup) != sizeof backup) { 150 perror("could not read backup bootblock"); 151 return FSFATAL; 152 } 153 backup[65] = block[65]; /* XXX */ 154 if (memcmp(block + 11, backup + 11, 79)) { 155 /* 156 * XXX We require a reference that explains 157 * that these bytes need to match, or should 158 * drop the check. gdt@NetBSD has observed 159 * filesystems that work fine under Windows XP 160 * and NetBSD that do not match, so the 161 * requirement is suspect. For now, just 162 * print out useful information and continue. 163 */ 164 pfatal("backup (block %d) mismatch with primary bootblock:\n", 165 boot->bpbBackup); 166 for (i = 11; i < 11 + 90; i++) { 167 if (block[i] != backup[i]) 168 pfatal("\ti=%d\tprimary 0x%02x\tbackup 0x%02x\n", 169 i, block[i], backup[i]); 170 } 171 } 172 /* Check backup bpbFSInfo? XXX */ 173 } 174 175 boot->ClusterOffset = (boot->bpbRootDirEnts * 32 + boot->bpbBytesPerSec - 1) 176 / boot->bpbBytesPerSec 177 + boot->bpbResSectors 178 + boot->bpbFATs * boot->FATsecs 179 - CLUST_FIRST * boot->bpbSecPerClust; 180 181 if (boot->bpbBytesPerSec % DOSBOOTBLOCKSIZE != 0) { 182 pfatal("Invalid sector size: %u", boot->bpbBytesPerSec); 183 return FSFATAL; 184 } 185 if (boot->bpbSecPerClust == 0) { 186 pfatal("Invalid cluster size: %u", boot->bpbSecPerClust); 187 return FSFATAL; 188 } 189 if (boot->bpbSectors) { 190 boot->bpbHugeSectors = 0; 191 boot->NumSectors = boot->bpbSectors; 192 } else 193 boot->NumSectors = boot->bpbHugeSectors; 194 boot->NumClusters = (boot->NumSectors - boot->ClusterOffset) / boot->bpbSecPerClust; 195 196 if (boot->flags&FAT32) 197 boot->ClustMask = CLUST32_MASK; 198 else if (boot->NumClusters < (CLUST_RSRVD&CLUST12_MASK)) 199 boot->ClustMask = CLUST12_MASK; 200 else if (boot->NumClusters < (CLUST_RSRVD&CLUST16_MASK)) 201 boot->ClustMask = CLUST16_MASK; 202 else { 203 pfatal("Filesystem too big (%u clusters) for non-FAT32 partition", 204 boot->NumClusters); 205 return FSFATAL; 206 } 207 208 switch (boot->ClustMask) { 209 case CLUST32_MASK: 210 boot->NumFatEntries = (boot->FATsecs * boot->bpbBytesPerSec) / 4; 211 break; 212 case CLUST16_MASK: 213 boot->NumFatEntries = (boot->FATsecs * boot->bpbBytesPerSec) / 2; 214 break; 215 default: 216 boot->NumFatEntries = (boot->FATsecs * boot->bpbBytesPerSec * 2) / 3; 217 break; 218 } 219 220 if (boot->NumFatEntries < boot->NumClusters) { 221 pfatal("FAT size too small, %u entries won't fit into %u sectors\n", 222 boot->NumClusters, boot->FATsecs); 223 return FSFATAL; 224 } 225 boot->ClusterSize = boot->bpbBytesPerSec * boot->bpbSecPerClust; 226 227 boot->NumFiles = 1; 228 boot->NumFree = 0; 229 230 return ret; 231 } 232 233 int 234 writefsinfo(int dosfs, struct bootblock *boot) 235 { 236 u_char fsinfo[2 * DOSBOOTBLOCKSIZE]; 237 238 if (lseek(dosfs, boot->bpbFSInfo * boot->bpbBytesPerSec, SEEK_SET) 239 != boot->bpbFSInfo * boot->bpbBytesPerSec 240 || read(dosfs, fsinfo, sizeof fsinfo) != sizeof fsinfo) { 241 perror("could not read fsinfo block"); 242 return FSFATAL; 243 } 244 fsinfo[0x1e8] = (u_char)boot->FSFree; 245 fsinfo[0x1e9] = (u_char)(boot->FSFree >> 8); 246 fsinfo[0x1ea] = (u_char)(boot->FSFree >> 16); 247 fsinfo[0x1eb] = (u_char)(boot->FSFree >> 24); 248 fsinfo[0x1ec] = (u_char)boot->FSNext; 249 fsinfo[0x1ed] = (u_char)(boot->FSNext >> 8); 250 fsinfo[0x1ee] = (u_char)(boot->FSNext >> 16); 251 fsinfo[0x1ef] = (u_char)(boot->FSNext >> 24); 252 if (lseek(dosfs, boot->bpbFSInfo * boot->bpbBytesPerSec, SEEK_SET) 253 != boot->bpbFSInfo * boot->bpbBytesPerSec 254 || write(dosfs, fsinfo, sizeof fsinfo) 255 != sizeof fsinfo) { 256 perror("Unable to write bpbFSInfo"); 257 return FSFATAL; 258 } 259 /* 260 * Technically, we should return FSBOOTMOD here. 261 * 262 * However, since Win95 OSR2 (the first M$ OS that has 263 * support for FAT32) doesn't maintain the FSINFO block 264 * correctly, it has to be fixed pretty often. 265 * 266 * Therefor, we handle the FSINFO block only informally, 267 * fixing it if necessary, but otherwise ignoring the 268 * fact that it was incorrect. 269 */ 270 return 0; 271 } 272