120 lines
4.1 KiB
C
120 lines
4.1 KiB
C
/* $NetBSD: boot.c,v 1.4 1997/09/14 14:40:10 lukem Exp $ */
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/*
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* Copyright (C) 1995 Wolfgang Solfrank
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* Copyright (c) 1995 Martin Husemann
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Martin Husemann
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* and Wolfgang Solfrank.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#ifndef lint
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__RCSID("$NetBSD: boot.c,v 1.4 1997/09/14 14:40:10 lukem Exp $");
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#endif /* not lint */
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#include <stdlib.h>
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#include <string.h>
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#include <ctype.h>
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#include <stdio.h>
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#include <unistd.h>
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#include "ext.h"
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#include "fsutil.h"
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int
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readboot(dosfs, boot)
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int dosfs;
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struct bootblock *boot;
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{
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u_char block[DOSBOOTBLOCKSIZE];
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int n;
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if ((n = read(dosfs, block, sizeof block)) < (int)sizeof block) {
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if (n < 0)
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perror("could not read boot block");
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else
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pfatal("Short bootblock?");
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return FSFATAL;
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}
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/* decode bios parameter block */
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boot->BytesPerSec = block[11] + (block[12] << 8);
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boot->SecPerClust = block[13];
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boot->ResSectors = block[14] + (block[15] << 8);
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boot->FATs = block[16];
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boot->RootDirEnts = block[17] + (block[18] << 8);
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boot->Sectors = block[19] + (block[20] << 8);
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boot->Media = block[21];
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boot->FATsecs = block[22] + (block[23] << 8);
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boot->SecPerTrack = block[24] + (block[25] << 8);
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boot->Heads = block[26] + (block[27] << 8);
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boot->HiddenSecs = block[28] + (block[29] << 8) + (block[30] << 16) + (block[31] << 24);
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boot->HugeSectors = block[32] + (block[33] << 8) + (block[34] << 16) + (block[35] << 24);
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boot->ClusterOffset = (boot->RootDirEnts * 32 + boot->BytesPerSec - 1)
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/ boot->BytesPerSec
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+ boot->ResSectors
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+ boot->FATs * boot->FATsecs
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- CLUST_FIRST * boot->SecPerClust;
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if (boot->BytesPerSec % DOSBOOTBLOCKSIZE != 0) {
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pfatal("Invalid sector size: %u\n", boot->BytesPerSec);
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return FSFATAL;
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}
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if (boot->SecPerClust == 0) {
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pfatal("Invalid cluster size: %u\n", boot->SecPerClust);
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return FSFATAL;
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}
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if (boot->Sectors) {
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boot->HugeSectors = 0;
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boot->NumSectors = boot->Sectors;
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} else
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boot->NumSectors = boot->HugeSectors;
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boot->NumClusters = (boot->NumSectors - boot->ClusterOffset) / boot->SecPerClust;
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if (boot->NumClusters >= MAX12BITCLUSTERS)
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boot->Is16BitFat = 1;
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else
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boot->Is16BitFat = 0;
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if (boot->Is16BitFat)
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boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec) / 2;
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else
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boot->NumFatEntries = (boot->FATsecs * boot->BytesPerSec * 2) / 3;
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if (boot->NumFatEntries < boot->NumClusters) {
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pfatal("FAT size too small, %d entries won't fit into %u sectors\n",
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boot->NumClusters, boot->FATsecs);
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return FSFATAL;
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}
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boot->ClusterSize = boot->BytesPerSec * boot->SecPerClust;
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boot->NumFiles = 1;
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boot->NumFree = 0;
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return FSOK;
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}
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