/* $OpenBSD: boot.c,v 1.9 2003/07/29 18:38:35 deraadt Exp $ */ /* $NetBSD: boot.c,v 1.5 1997/10/17 11:19:23 ws Exp $ */ /* * Copyright (C) 1995, 1997 Wolfgang Solfrank * Copyright (c) 1995 Martin Husemann * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by Martin Husemann * and Wolfgang Solfrank. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #ifndef lint static char rcsid[] = "$OpenBSD: boot.c,v 1.9 2003/07/29 18:38:35 deraadt Exp $"; #endif /* not lint */ #include <stdlib.h> #include <string.h> #include <ctype.h> #include <stdio.h> #include <unistd.h> #include "ext.h" int readboot(dosfs, boot) int dosfs; struct bootblock *boot; { u_char block[DOSBOOTBLOCKSIZE]; u_char fsinfo[2 * DOSBOOTBLOCKSIZE]; u_char backup[DOSBOOTBLOCKSIZE]; int ret = FSOK; if (read(dosfs, block, sizeof block) < sizeof block) { perror("could not read boot block"); return (FSFATAL); } if (block[510] != 0x55 || block[511] != 0xaa) { pfatal("Invalid signature in boot block: %02x%02x\n", block[511], block[510]); return FSFATAL; } memset(boot, 0, sizeof *boot); boot->ValidFat = -1; /* decode bios parameter block */ boot->BytesPerSec = block[11] + (block[12] << 8); boot->SecPerClust = block[13]; boot->ResSectors = block[14] + (block[15] << 8); boot->FATs = block[16]; boot->RootDirEnts = block[17] + (block[18] << 8); boot->Sectors = block[19] + (block[20] << 8); boot->Media = block[21]; boot->FATsmall = block[22] + (block[23] << 8); boot->SecPerTrack = block[24] + (block[25] << 8); boot->Heads = block[26] + (block[27] << 8); boot->HiddenSecs = block[28] + (block[29] << 8) + (block[30] << 16) + (block[31] << 24); boot->HugeSectors = block[32] + (block[33] << 8) + (block[34] << 16) + (block[35] << 24); boot->FATsecs = boot->FATsmall; if (!boot->RootDirEnts) boot->flags |= FAT32; if (boot->flags & FAT32) { boot->FATsecs = block[36] + (block[37] << 8) + (block[38] << 16) + (block[39] << 24); if (block[40] & 0x80) boot->ValidFat = block[40] & 0x0f; /* check version number: */ if (block[42] || block[43]) { /* Correct? XXX */ pfatal("Unknown filesystem version: %x.%x\n", block[43], block[42]); return FSFATAL; } boot->RootCl = block[44] + (block[45] << 8) + (block[46] << 16) + (block[47] << 24); boot->FSInfo = block[48] + (block[49] << 8); boot->Backup = block[50] + (block[51] << 8); if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) != boot->FSInfo * boot->BytesPerSec || read(dosfs, fsinfo, sizeof fsinfo) != sizeof fsinfo) { perror("could not read fsinfo block"); return FSFATAL; } if (memcmp(fsinfo, "RRaA", 4) || memcmp(fsinfo + 0x1e4, "rrAa", 4) || fsinfo[0x1fc] || fsinfo[0x1fd] || fsinfo[0x1fe] != 0x55 || fsinfo[0x1ff] != 0xaa || fsinfo[0x3fc] || fsinfo[0x3fd] || fsinfo[0x3fe] != 0x55 || fsinfo[0x3ff] != 0xaa) { pwarn("Invalid signature in fsinfo block"); if (ask(0, "fix")) { memcpy(fsinfo, "RRaA", 4); memcpy(fsinfo + 0x1e4, "rrAa", 4); fsinfo[0x1fc] = fsinfo[0x1fd] = 0; fsinfo[0x1fe] = 0x55; fsinfo[0x1ff] = 0xaa; fsinfo[0x3fc] = fsinfo[0x3fd] = 0; fsinfo[0x3fe] = 0x55; fsinfo[0x3ff] = 0xaa; if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) != boot->FSInfo * boot->BytesPerSec || write(dosfs, fsinfo, sizeof fsinfo) != sizeof fsinfo) { perror("Unable to write FSInfo"); return FSFATAL; } ret = FSBOOTMOD; } else boot->FSInfo = 0; } if (boot->FSInfo) { boot->FSFree = fsinfo[0x1e8] + (fsinfo[0x1e9] << 8) + (fsinfo[0x1ea] << 16) + (fsinfo[0x1eb] << 24); boot->FSNext = fsinfo[0x1ec] + (fsinfo[0x1ed] << 8) + (fsinfo[0x1ee] << 16) + (fsinfo[0x1ef] << 24); } if (lseek(dosfs, boot->Backup * boot->BytesPerSec, SEEK_SET) != boot->Backup * boot->BytesPerSec || read(dosfs, backup, sizeof backup) != sizeof backup) { perror("could not read backup bootblock"); return FSFATAL; } if (memcmp(block, backup, DOSBOOTBLOCKSIZE)) { /* Correct? XXX */ pfatal("backup doesn't compare to primary bootblock\n"); return FSFATAL; } /* Check backup FSInfo? XXX */ } if (boot->BytesPerSec == 0 || boot->BytesPerSec % DOSBOOTBLOCKSIZE != 0) { pfatal("Invalid sector size: %u\n", boot->BytesPerSec); return (FSFATAL); } if (boot->SecPerClust == 0) { pfatal("Invalid cluster size: %u\n", boot->SecPerClust); return (FSFATAL); } boot->ClusterOffset = (boot->RootDirEnts * 32 + boot->BytesPerSec - 1) / boot->BytesPerSec + boot->ResSectors + boot->FATs * boot->FATsecs - CLUST_FIRST * boot->SecPerClust; if (boot->Sectors) { boot->HugeSectors = 0; boot->NumSectors = boot->Sectors; } else boot->NumSectors = boot->HugeSectors; boot->NumClusters = (boot->NumSectors - boot->ClusterOffset) / boot->SecPerClust; if (boot->flags&FAT32) boot->ClustMask = CLUST32_MASK; else if (boot->NumClusters < (CLUST_RSRVD&CLUST12_MASK)) boot->ClustMask = CLUST12_MASK; else if (boot->NumClusters < (CLUST_RSRVD&CLUST16_MASK)) boot->ClustMask = CLUST16_MASK; else { pfatal("Filesystem too big (%u clusters) for non-FAT32 partition\n", boot->NumClusters); return FSFATAL; } switch (boot->ClustMask) { case CLUST32_MASK: boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec) / 4; break; case CLUST16_MASK: boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec) / 2; break; default: boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec * 2) / 3; break; } if (boot->NumFatEntries < boot->NumClusters) { pfatal("FAT size too small, %u entries won't fit into %u sectors\n", boot->NumClusters, boot->FATsecs); return (FSFATAL); } boot->ClusterSize = boot->BytesPerSec * boot->SecPerClust; boot->NumFiles = 1; boot->NumFree = 0; return ret; } int writefsinfo(dosfs, boot) int dosfs; struct bootblock *boot; { u_char fsinfo[2 * DOSBOOTBLOCKSIZE]; if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) != boot->FSInfo * boot->BytesPerSec || read(dosfs, fsinfo, sizeof fsinfo) != sizeof fsinfo) { perror("could not read fsinfo block"); return FSFATAL; } fsinfo[0x1e8] = (u_char)boot->FSFree; fsinfo[0x1e9] = (u_char)(boot->FSFree >> 8); fsinfo[0x1ea] = (u_char)(boot->FSFree >> 16); fsinfo[0x1eb] = (u_char)(boot->FSFree >> 24); fsinfo[0x1ec] = (u_char)boot->FSNext; fsinfo[0x1ed] = (u_char)(boot->FSNext >> 8); fsinfo[0x1ee] = (u_char)(boot->FSNext >> 16); fsinfo[0x1ef] = (u_char)(boot->FSNext >> 24); if (lseek(dosfs, boot->FSInfo * boot->BytesPerSec, SEEK_SET) != boot->FSInfo * boot->BytesPerSec || write(dosfs, fsinfo, sizeof fsinfo) != sizeof fsinfo) { perror("Unable to write FSInfo"); return FSFATAL; } /* * Technically, we should return FSBOOTMOD here. * * However, since Win95 OSR2 (the first M$ OS that has * support for FAT32) doesn't maintain the FSINFO block * correctly, it has to be fixed pretty often. * * Therefor, we handle the FSINFO block only informally, * fixing it if necessary, but otherwise ignoring the * fact that it was incorrect. */ return 0; }