| File: | src/sbin/fsck_msdos/boot.c |
| Warning: | line 65, column 7 Although the value stored to 'o' is used in the enclosing expression, the value is never actually read from 'o' |
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| 1 | /* $OpenBSD: boot.c,v 1.24 2016/10/10 00:34:50 bluhm 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 | * |
| 17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR |
| 18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| 20 | * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| 26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 27 | */ |
| 28 | |
| 29 | #include <sys/param.h> /* DEV_BSIZE powerof2 */ |
| 30 | #include <sys/disklabel.h> |
| 31 | |
| 32 | #include <stdlib.h> |
| 33 | #include <string.h> |
| 34 | #include <ctype.h> |
| 35 | #include <stdio.h> |
| 36 | #include <unistd.h> |
| 37 | |
| 38 | #include "ext.h" |
| 39 | |
| 40 | int |
| 41 | readboot(int dosfs, struct bootblock *boot) |
| 42 | { |
| 43 | u_char *block = NULL((void *)0); |
| 44 | u_char *fsinfo = NULL((void *)0); |
| 45 | u_char *backup = NULL((void *)0); |
| 46 | int ret = FSOK0, secsize = lab.d_secsize, fsinfosz; |
| 47 | off_t o; |
| 48 | ssize_t n; |
| 49 | |
| 50 | if (secsize < DOSBOOTBLOCKSIZE512) { |
| 51 | xperror("sector size < DOSBOOTBLOCKSIZE"); |
| 52 | goto fail; |
| 53 | } |
| 54 | if (DOSBOOTBLOCKSIZE512 != DEV_BSIZE(1 << 9)) { |
| 55 | xperror("DOSBOOTBLOCKSIZE != DEV_BSIZE"); |
| 56 | goto fail; |
| 57 | } |
| 58 | |
| 59 | block = malloc(secsize); |
| 60 | if (block == NULL((void *)0)) { |
| 61 | xperror("could not malloc boot block"); |
| 62 | goto fail; |
| 63 | } |
| 64 | |
| 65 | if ((o = lseek(dosfs, 0, SEEK_SET0)) == -1) { |
Although the value stored to 'o' is used in the enclosing expression, the value is never actually read from 'o' | |
| 66 | xperror("could not seek boot block"); |
| 67 | goto fail; |
| 68 | } |
| 69 | |
| 70 | n = read(dosfs, block, secsize); |
| 71 | if (n == -1 || n != secsize) { |
| 72 | xperror("could not read boot block"); |
| 73 | goto fail; |
| 74 | } |
| 75 | |
| 76 | if (block[510] != 0x55 || block[511] != 0xaa) { |
| 77 | pfatal("Invalid signature in boot block: %02x%02x\n", |
| 78 | block[511], block[510]); |
| 79 | } |
| 80 | |
| 81 | memset(boot, 0, sizeof *boot); |
| 82 | boot->ValidFat = -1; |
| 83 | |
| 84 | /* decode bios parameter block */ |
| 85 | boot->BytesPerSec = block[11] + (block[12] << 8); |
| 86 | if (boot->BytesPerSec == 0 || boot->BytesPerSec != secsize) { |
| 87 | pfatal("Invalid sector size: %u\n", boot->BytesPerSec); |
| 88 | goto fail; |
| 89 | } |
| 90 | boot->SecPerClust = block[13]; |
| 91 | if (boot->SecPerClust == 0 || !powerof2(boot->SecPerClust)((((boot->SecPerClust)-1)&(boot->SecPerClust))==0)) { |
| 92 | pfatal("Invalid cluster size: %u\n", boot->SecPerClust); |
| 93 | goto fail; |
| 94 | } |
| 95 | boot->ResSectors = block[14] + (block[15] << 8); |
| 96 | boot->FATs = block[16]; |
| 97 | if (boot->FATs == 0) { |
| 98 | pfatal("Invalid number of FATs: %u\n", boot->FATs); |
| 99 | goto fail; |
| 100 | } |
| 101 | boot->RootDirEnts = block[17] + (block[18] << 8); |
| 102 | boot->Sectors = block[19] + (block[20] << 8); |
| 103 | boot->Media = block[21]; |
| 104 | boot->FATsmall = block[22] + (block[23] << 8); |
| 105 | boot->SecPerTrack = block[24] + (block[25] << 8); |
| 106 | boot->Heads = block[26] + (block[27] << 8); |
| 107 | boot->HiddenSecs = block[28] + (block[29] << 8) + (block[30] << 16) + (block[31] << 24); |
| 108 | boot->HugeSectors = block[32] + (block[33] << 8) + (block[34] << 16) + (block[35] << 24); |
| 109 | |
| 110 | boot->FATsecs = boot->FATsmall; |
| 111 | |
| 112 | if (!boot->RootDirEnts) { |
| 113 | boot->flags |= FAT321; |
| 114 | boot->FATsecs = block[36] + (block[37] << 8) |
| 115 | + (block[38] << 16) + (block[39] << 24); |
| 116 | if (block[40] & 0x80) |
| 117 | boot->ValidFat = block[40] & 0x0f; |
| 118 | |
| 119 | /* check version number: */ |
| 120 | if (block[42] || block[43]) { |
| 121 | /* Correct? XXX */ |
| 122 | pfatal("Unknown filesystem version: %x.%x\n", |
| 123 | block[43], block[42]); |
| 124 | goto fail; |
| 125 | } |
| 126 | boot->RootCl = block[44] + (block[45] << 8) |
| 127 | + (block[46] << 16) + (block[47] << 24); |
| 128 | boot->FSInfo = block[48] + (block[49] << 8); |
| 129 | boot->Backup = block[50] + (block[51] << 8); |
| 130 | |
| 131 | o = lseek(dosfs, boot->FSInfo * secsize, SEEK_SET0); |
| 132 | if (o == -1 || o != boot->FSInfo * secsize) { |
| 133 | xperror("could not seek fsinfo block"); |
| 134 | goto fail; |
| 135 | } |
| 136 | |
| 137 | if ((2 * DOSBOOTBLOCKSIZE512) < secsize) |
| 138 | fsinfosz = secsize; |
| 139 | else |
| 140 | fsinfosz = 2 * secsize; |
| 141 | fsinfo = malloc(fsinfosz); |
| 142 | if (fsinfo == NULL((void *)0)) { |
| 143 | xperror("could not malloc fsinfo"); |
| 144 | goto fail; |
| 145 | } |
| 146 | n = read(dosfs, fsinfo, fsinfosz); |
| 147 | if (n == -1 || n != fsinfosz) { |
| 148 | xperror("could not read fsinfo block"); |
| 149 | goto fail; |
| 150 | } |
| 151 | |
| 152 | if (memcmp(fsinfo, "RRaA", 4) |
| 153 | || memcmp(fsinfo + 0x1e4, "rrAa", 4) |
| 154 | || fsinfo[0x1fc] |
| 155 | || fsinfo[0x1fd] |
| 156 | || fsinfo[0x1fe] != 0x55 |
| 157 | || fsinfo[0x1ff] != 0xaa |
| 158 | || fsinfo[0x3fc] |
| 159 | || fsinfo[0x3fd] |
| 160 | || fsinfo[0x3fe] != 0x55 |
| 161 | || fsinfo[0x3ff] != 0xaa) { |
| 162 | pwarn("Invalid signature in fsinfo block\n"); |
| 163 | if (ask(0, "fix")) { |
| 164 | memcpy(fsinfo, "RRaA", 4); |
| 165 | memcpy(fsinfo + 0x1e4, "rrAa", 4); |
| 166 | fsinfo[0x1fc] = fsinfo[0x1fd] = 0; |
| 167 | fsinfo[0x1fe] = 0x55; |
| 168 | fsinfo[0x1ff] = 0xaa; |
| 169 | fsinfo[0x3fc] = fsinfo[0x3fd] = 0; |
| 170 | fsinfo[0x3fe] = 0x55; |
| 171 | fsinfo[0x3ff] = 0xaa; |
| 172 | |
| 173 | o = lseek(dosfs, boot->FSInfo * secsize, |
| 174 | SEEK_SET0); |
| 175 | if (o == -1 || o != boot->FSInfo * secsize) { |
| 176 | xperror("Unable to seek FSInfo"); |
| 177 | goto fail; |
| 178 | } |
| 179 | n = write(dosfs, fsinfo, fsinfosz); |
| 180 | if (n == -1 || n != fsinfosz) { |
| 181 | xperror("Unable to write FSInfo"); |
| 182 | goto fail; |
| 183 | } |
| 184 | ret = FSBOOTMOD1; |
| 185 | } else |
| 186 | boot->FSInfo = 0; |
| 187 | } |
| 188 | if (boot->FSInfo) { |
| 189 | boot->FSFree = fsinfo[0x1e8] + (fsinfo[0x1e9] << 8) |
| 190 | + (fsinfo[0x1ea] << 16) |
| 191 | + (fsinfo[0x1eb] << 24); |
| 192 | boot->FSNext = fsinfo[0x1ec] + (fsinfo[0x1ed] << 8) |
| 193 | + (fsinfo[0x1ee] << 16) |
| 194 | + (fsinfo[0x1ef] << 24); |
| 195 | } |
| 196 | |
| 197 | o = lseek(dosfs, boot->Backup * secsize, SEEK_SET0); |
| 198 | if (o == -1 || o != boot->Backup * secsize) { |
| 199 | xperror("could not seek backup bootblock"); |
| 200 | goto fail; |
| 201 | } |
| 202 | backup = malloc(2 * secsize); /* In case we check fsinfo. */ |
| 203 | if (backup == NULL((void *)0)) { |
| 204 | xperror("could not malloc backup boot block"); |
| 205 | goto fail; |
| 206 | } |
| 207 | n = read(dosfs, backup, secsize); |
| 208 | if (n == -1 || n != secsize) { |
| 209 | xperror("could not read backup bootblock"); |
| 210 | goto fail; |
| 211 | } |
| 212 | |
| 213 | /* |
| 214 | * Check that the backup boot block matches the primary one. |
| 215 | * We don't check every byte, since some vendor utilities |
| 216 | * seem to overwrite the boot code when they feel like it, |
| 217 | * without changing the backup block. Specifically, we check |
| 218 | * the two-byte signature at the end, the BIOS parameter |
| 219 | * block (which starts after the 3-byte JMP and the 8-byte |
| 220 | * OEM name/version) and the filesystem information that |
| 221 | * follows the BPB (bsBPB[53] and bsExt[26] for FAT32, so we |
| 222 | * check 79 bytes). |
| 223 | */ |
| 224 | if (backup[510] != 0x55 || backup[511] != 0xaa) { |
| 225 | pfatal("Invalid signature in backup boot block: %02x%02x\n", backup[511], backup[510]); |
| 226 | } |
| 227 | if (memcmp(block + 11, backup + 11, 79)) { |
| 228 | pfatal("backup doesn't compare to primary bootblock\n"); |
| 229 | goto fail; |
| 230 | } |
| 231 | /* Check backup FSInfo? XXX */ |
| 232 | } |
| 233 | |
| 234 | if (boot->FATsecs == 0) { |
| 235 | pfatal("Invalid number of FAT sectors: %u\n", boot->FATsecs); |
| 236 | goto fail; |
| 237 | } |
| 238 | |
| 239 | boot->ClusterOffset = (boot->RootDirEnts * 32 + secsize - 1) |
| 240 | / secsize |
| 241 | + boot->ResSectors |
| 242 | + boot->FATs * boot->FATsecs |
| 243 | - CLUST_FIRST2 * boot->SecPerClust; |
| 244 | |
| 245 | if (boot->Sectors) { |
| 246 | boot->HugeSectors = 0; |
| 247 | boot->NumSectors = boot->Sectors; |
| 248 | } else |
| 249 | boot->NumSectors = boot->HugeSectors; |
| 250 | |
| 251 | if (boot->ClusterOffset > boot->NumSectors) { |
| 252 | pfatal("Cluster offset too large (%u clusters)\n", |
| 253 | boot->ClusterOffset); |
| 254 | goto fail; |
| 255 | } |
| 256 | boot->NumClusters = (boot->NumSectors - boot->ClusterOffset) / boot->SecPerClust; |
| 257 | |
| 258 | if (boot->flags&FAT321) |
| 259 | boot->ClustMask = CLUST32_MASK0xfffffff; |
| 260 | else if (boot->NumClusters < (CLUST_RSRVD0xfffffff6&CLUST12_MASK0xfff)) |
| 261 | boot->ClustMask = CLUST12_MASK0xfff; |
| 262 | else if (boot->NumClusters < (CLUST_RSRVD0xfffffff6&CLUST16_MASK0xffff)) |
| 263 | boot->ClustMask = CLUST16_MASK0xffff; |
| 264 | else { |
| 265 | pfatal("Filesystem too big (%u clusters) for non-FAT32 partition\n", |
| 266 | boot->NumClusters); |
| 267 | goto fail; |
| 268 | } |
| 269 | |
| 270 | switch (boot->ClustMask) { |
| 271 | case CLUST32_MASK0xfffffff: |
| 272 | boot->NumFatEntries = (boot->FATsecs * secsize) / 4; |
| 273 | break; |
| 274 | case CLUST16_MASK0xffff: |
| 275 | boot->NumFatEntries = (boot->FATsecs * secsize) / 2; |
| 276 | break; |
| 277 | default: |
| 278 | boot->NumFatEntries = (boot->FATsecs * secsize * 2) / 3; |
| 279 | break; |
| 280 | } |
| 281 | |
| 282 | if (boot->NumFatEntries < boot->NumClusters) { |
| 283 | pfatal("FAT size too small, %u entries won't fit into %u sectors\n", |
| 284 | boot->NumClusters, boot->FATsecs); |
| 285 | goto fail; |
| 286 | } |
| 287 | boot->ClusterSize = boot->SecPerClust * secsize; |
| 288 | |
| 289 | boot->NumFiles = 1; |
| 290 | boot->NumFree = 0; |
| 291 | |
| 292 | free(backup); |
| 293 | free(block); |
| 294 | free(fsinfo); |
| 295 | return ret; |
| 296 | fail: |
| 297 | free(backup); |
| 298 | free(block); |
| 299 | free(fsinfo); |
| 300 | return FSFATAL16; |
| 301 | } |
| 302 | |
| 303 | int |
| 304 | writefsinfo(int dosfs, struct bootblock *boot) |
| 305 | { |
| 306 | u_char *fsinfo = NULL((void *)0); |
| 307 | int secsize = lab.d_secsize, fsinfosz; |
| 308 | off_t o; |
| 309 | ssize_t n; |
| 310 | |
| 311 | if ((2 * DOSBOOTBLOCKSIZE512) < secsize) |
| 312 | fsinfosz = secsize; |
| 313 | else |
| 314 | fsinfosz = 2 * secsize; |
| 315 | |
| 316 | fsinfo = malloc(fsinfosz); |
| 317 | if (fsinfo == NULL((void *)0)) { |
| 318 | xperror("could not malloc fsinfo block"); |
| 319 | goto fail; |
| 320 | } |
| 321 | |
| 322 | o = lseek(dosfs, boot->FSInfo * secsize, SEEK_SET0); |
| 323 | if (o == -1 || o != boot->FSInfo * secsize) { |
| 324 | xperror("could not seek fsinfo block"); |
| 325 | goto fail; |
| 326 | } |
| 327 | |
| 328 | n = read(dosfs, fsinfo, fsinfosz); |
| 329 | if (n == -1 || n != fsinfosz) { |
| 330 | xperror("could not read fsinfo block"); |
| 331 | goto fail; |
| 332 | } |
| 333 | |
| 334 | fsinfo[0x1e8] = (u_char)boot->FSFree; |
| 335 | fsinfo[0x1e9] = (u_char)(boot->FSFree >> 8); |
| 336 | fsinfo[0x1ea] = (u_char)(boot->FSFree >> 16); |
| 337 | fsinfo[0x1eb] = (u_char)(boot->FSFree >> 24); |
| 338 | fsinfo[0x1ec] = (u_char)boot->FSNext; |
| 339 | fsinfo[0x1ed] = (u_char)(boot->FSNext >> 8); |
| 340 | fsinfo[0x1ee] = (u_char)(boot->FSNext >> 16); |
| 341 | fsinfo[0x1ef] = (u_char)(boot->FSNext >> 24); |
| 342 | |
| 343 | o = lseek(dosfs, o, SEEK_SET0); |
| 344 | if (o == -1 || o != boot->FSInfo * boot->BytesPerSec) { |
| 345 | xperror("Unable to seek FSInfo"); |
| 346 | goto fail; |
| 347 | } |
| 348 | n = write(dosfs, fsinfo, fsinfosz); |
| 349 | if (n == -1 || n != fsinfosz) { |
| 350 | xperror("Unable to write FSInfo"); |
| 351 | goto fail; |
| 352 | } |
| 353 | |
| 354 | free(fsinfo); |
| 355 | |
| 356 | /* |
| 357 | * Technically, we should return FSBOOTMOD here. |
| 358 | * |
| 359 | * However, since Win95 OSR2 (the first M$ OS that has |
| 360 | * support for FAT32) doesn't maintain the FSINFO block |
| 361 | * correctly, it has to be fixed pretty often. |
| 362 | * |
| 363 | * Therefore, we handle the FSINFO block only informally, |
| 364 | * fixing it if necessary, but otherwise ignoring the |
| 365 | * fact that it was incorrect. |
| 366 | */ |
| 367 | return 0; |
| 368 | fail: |
| 369 | free(fsinfo); |
| 370 | return FSFATAL16; |
| 371 | } |