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/* This is part of um-ViewOS
* The user-mode implementation of OSVIEW -- A Process with a View
*
* MBR: Library to read MBR and Extended MBR
* Copyright (C) 2006 Renzo Davoli <renzo@cs.unibo.it>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <string.h>
#include <linux/fs.h>
#include <config.h>
#include <sys/ioctl.h>
#include "mbr.h"
#define IDE_HEADER_OFFSET 446
static char mbrsignature[2]={0x55,0xAA};
struct mbr_header {
char code[IDE_HEADER_OFFSET];
struct mbrpart {
unsigned char flags;
unsigned char chs_begin[3];
unsigned char type;
unsigned char chs_end[3];
unsigned char lba_begin[4];
unsigned char lba_noblocks[4];
} mbrpart[4];
unsigned char signature[2];
};
#define LE32_INT(X) (((X)[0])+(((X)[1])<<8)+(((X)[2])<<16)+(((X)[3])<<24))
static void maxgeom(struct hd_geometry *geom, const unsigned char *chs)
{
unsigned char s,h;
unsigned short c;
h=chs[0];
s=chs[1] & 0x3f;
c=chs[2] + ((chs[1] & 0xc0) << 2);
if ((h+1) > geom->heads)
geom->heads = h+1;
if (s > geom->sectors)
geom->sectors = s;
if (c > geom->cylinders)
geom->cylinders = c;
}
static void mbr_read(struct mbr *mbr)
{
struct mbr_header mbr_header;
unsigned int ext_part_base=0;
pread64(mbr->fd, &mbr_header, sizeof(mbr_header), (off_t) 0);
if (memcmp(mbr_header.signature,mbrsignature,2) != 0) {
fprintf(stderr,"bad signature in MBR %x %x\n",
mbr_header.signature[0],mbr_header.signature[1]);
} else {
/* MBR is okay. Read MBR */
int i;
unsigned int offset=0;
memset(&(mbr->geometry),0,sizeof(struct hd_geometry));
for (i=0;i<4;i++) {
if(mbr_header.mbrpart[i].type != 0) {
struct partition *new=mbr->part[i]=malloc(sizeof(struct partition));
maxgeom(&(mbr->geometry),mbr_header.mbrpart[i].chs_end);
new->flags=mbr_header.mbrpart[i].flags;
new->type=mbr_header.mbrpart[i].type;
new->LBAbegin=LE32_INT(mbr_header.mbrpart[i].lba_begin);
new->LBAnoblocks=LE32_INT(mbr_header.mbrpart[i].lba_noblocks);
if(mbr_header.mbrpart[i].type == 5) {/* extended partition*/
if (ext_part_base==0)
ext_part_base=new->LBAbegin;
else
fprintf(stderr,"There are more than one extended partitions against the specifications\n");
}
}
}
if (mbr->geometry.heads == 0)
mbr->geometry.heads = 255;
if (mbr->geometry.sectors == 0)
mbr->geometry.sectors = 63;
mbr->geometry.cylinders = (mbr->size >> IDE_BLOCKSIZE_LOG) / (mbr->geometry.heads * mbr->geometry.sectors);
/* Read the chain of logical partitions inside the extended partition */
while (ext_part_base > 0) {
off_t base=((off_t)(ext_part_base+offset)) << IDE_BLOCKSIZE_LOG;
pread64(mbr->fd, &mbr_header, sizeof(mbr_header), base);
if (memcmp(mbr_header.signature,mbrsignature,2) != 0) {
fprintf(stderr,"bad signature in block %lld=%x %x\n", base,
mbr_header.signature[0],mbr_header.signature[1]);
ext_part_base=0;
} else {
if(mbr_header.mbrpart[0].type != 0) {
struct partition *new=mbr->part[i]=malloc(sizeof(struct partition));
new->flags=mbr_header.mbrpart[0].flags;
new->type=mbr_header.mbrpart[0].type;
new->LBAbegin=LE32_INT(mbr_header.mbrpart[0].lba_begin)+ext_part_base+offset;
new->LBAnoblocks=LE32_INT(mbr_header.mbrpart[0].lba_noblocks);
i++;
}
if(mbr_header.mbrpart[1].type == 5)
offset=LE32_INT(mbr_header.mbrpart[1].lba_begin);
else
ext_part_base=0;
}
}
}
}
void mbr_printpt(struct mbr *mbr)
{
int i;
for(i=0;i<IDE_MAXPART;i++) {
if (mbr->part[i]) {
fprintf(stderr,"PART %-2d F%02x T%02x B=%10d S=%10d\n",i,
mbr->part[i]->flags,mbr->part[i]->type,mbr->part[i]->LBAbegin,mbr->part[i]->LBAnoblocks);
}
}
}
void mbr_reread(struct mbr *mbr)
{
int i;
for(i=0;i<IDE_MAXPART;i++) {
if (mbr->part[i]) {
free(mbr->part[i]);
mbr->part[i]=0;
}
}
mbr_read(mbr);
}
struct mbr *mbr_open(int fd)
{
off_t size=lseek(fd,0,SEEK_END);
if (size < 0) {
/* maybe it is a device */
long long lsize=-1;
if (ioctl(fd,BLKGETSIZE64,&lsize) >= 0)
size=lsize;
}
if (size > 0) {
struct mbr *mbr=calloc(1,sizeof(struct mbr));
mbr->fd=fd;
mbr->size=size;
mbr_read(mbr);
return mbr;
} else {
return NULL;
}
}
void mbr_close(struct mbr *mbr)
{
close(mbr->fd);
free(mbr);
}
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