OpenBSD源代碼閱讀/sbin/part.c

半斤紅薯

               
               
                /*    $OpenBSD: part.c,v 1.42 2006/06/09 17:01:47 deraadt Exp $    */
/*
* Copyright (c) 1997 Tobias Weingartner
* All rights reserved.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*/
#include err.h>
#include util.h>
#include stdio.h>
#include string.h>
#include unistd.h>
#include sys/fcntl.h>
#include sys/types.h>
#include sys/stat.h>
#include sys/disklabel.h>
#include machine/param.h>
#include "disk.h"
#include "misc.h"
#include "mbr.h"
磁盤的分區(qū)表結(jié)構(gòu)說明如下：
字節(jié)
說明
0
是否是活動(dòng)分區(qū)：0x80表示活動(dòng)分區(qū)，0x00表示普通分區(qū)
1
分區(qū)起始磁頭號(hào)
2,3
2字節(jié)低6位表示起始扇區(qū)號(hào)，2字節(jié)高兩位+3字節(jié)表示柱面號(hào)
4
分區(qū)文件系統(tǒng)標(biāo)志
5，6，7
分區(qū)結(jié)束柱面號(hào)，磁頭號(hào)，扇區(qū)號(hào)，意義同1，2，3相同
8,9,10,11
邏輯起始扇區(qū)號(hào)，表示在這個(gè)分區(qū)之前的扇區(qū)數(shù)
12,13,14,15
表示這個(gè)分區(qū)占用的扇區(qū)個(gè)數(shù)
void
PRT_parse(disk_t *disk, void *prt, off_t offset, off_t reloff,
    prt_t *partn)
{
    unsigned char *p = prt;
    off_t off;
    partn->flag = *p++;
    partn->shead = *p++;
    partn->ssect = (*p) & 0x3F;
    partn->scyl = ((*p  2) & 0xFF00) | (*(p+1));
    p += 2;
    partn->id = *p++;
    partn->ehead = *p++;
    partn->esect = (*p) & 0x3F;
    partn->ecyl = ((*p  2) & 0xFF00) | (*(p+1));
    p += 2;
    if ((partn->id == DOSPTYP_EXTEND) || (partn->id == DOSPTYP_EXTENDL))
        off = reloff;
    else
        off = offset;
    partn->bs = getlong(p) + off;
    partn->ns = getlong(p+4);
    PRT_fix_CHS(disk, partn);
}


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