ref: f5cc6fbe3a7bcf8bdb002c646ddd519014afafd2
dir: /os/boot/pc/part.c/
#include "u.h"
#include "lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "sd.h"
#include "fs.h"
enum {
Npart = 32
};
uchar *mbrbuf, *partbuf;
int nbuf;
#define trace 0
int
tsdbio(SDunit *unit, SDpart *part, void *a, vlong off, int mbr)
{
uchar *b;
if(sdbio(unit, part, a, unit->secsize, off) != unit->secsize){
if(trace)
print("%s: read %lud at %lld failed\n", unit->name,
unit->secsize, (vlong)part->start*unit->secsize+off);
return -1;
}
b = a;
if(mbr && (b[0x1FE] != 0x55 || b[0x1FF] != 0xAA)){
if(trace)
print("%s: bad magic %.2ux %.2ux at %lld\n",
unit->name, b[0x1FE], b[0x1FF],
(vlong)part->start*unit->secsize+off);
return -1;
}
return 0;
}
/*
* read partition table. The partition table is just ascii strings.
*/
#define MAGIC "plan9 partitions"
static void
oldp9part(SDunit *unit)
{
SDpart *pp;
char *field[3], *line[Npart+1];
ulong n, start, end;
int i;
/*
* We have some partitions already.
*/
pp = &unit->part[unit->npart];
/*
* We prefer partition tables on the second to last sector,
* but some old disks use the last sector instead.
*/
strcpy(pp->name, "partition");
pp->start = unit->sectors - 2;
pp->end = unit->sectors - 1;
if(tsdbio(unit, pp, partbuf, 0, 0) < 0)
return;
if(strncmp((char*)partbuf, MAGIC, sizeof(MAGIC)-1) != 0) {
/* not found on 2nd last sector; look on last sector */
pp->start++;
pp->end++;
if(tsdbio(unit, pp, partbuf, 0, 0) < 0)
return;
if(strncmp((char*)partbuf, MAGIC, sizeof(MAGIC)-1) != 0)
return;
print("%s: using old plan9 partition table on last sector\n", unit->name);
}else
print("%s: using old plan9 partition table on 2nd-to-last sector\n", unit->name);
/* we found a partition table, so add a partition partition */
unit->npart++;
partbuf[unit->secsize-1] = '\0';
/*
* parse partition table
*/
n = getfields((char*)partbuf, line, Npart+1, '\n');
if(n && strncmp(line[0], MAGIC, sizeof(MAGIC)-1) == 0){
for(i = 1; i < n && unit->npart < SDnpart; i++){
if(getfields(line[i], field, 3, ' ') != 3)
break;
start = strtoull(field[1], 0, 0);
end = strtoull(field[2], 0, 0);
if(start >= end || end > unit->sectors)
break;
sdaddpart(unit, field[0], start, end);
}
}
}
static void
p9part(SDunit *unit, char *name)
{
SDpart *p;
char *field[4], *line[Npart+1];
uvlong start, end;
int i, n;
p = sdfindpart(unit, name);
if(p == nil)
return;
if(tsdbio(unit, p, partbuf, unit->secsize, 0) < 0)
return;
partbuf[unit->secsize-1] = '\0';
if(strncmp((char*)partbuf, "part ", 5) != 0)
return;
n = getfields((char*)partbuf, line, Npart+1, '\n');
if(n == 0)
return;
for(i = 0; i < n && unit->npart < SDnpart; i++){
if(strncmp(line[i], "part ", 5) != 0)
break;
if(getfields(line[i], field, 4, ' ') != 4)
break;
start = strtoull(field[2], 0, 0);
end = strtoull(field[3], 0, 0);
if(start >= end || end > unit->sectors)
break;
sdaddpart(unit, field[1], p->start+start, p->start+end);
}
}
int
isdos(int t)
{
return t==FAT12 || t==FAT16 || t==FATHUGE || t==FAT32 || t==FAT32X;
}
int
isextend(int t)
{
return t==EXTEND || t==EXTHUGE || t==LEXTEND;
}
/*
* Fetch the first dos and all plan9 partitions out of the MBR partition table.
* We return -1 if we did not find a plan9 partition.
*/
static int
mbrpart(SDunit *unit)
{
Dospart *dp;
ulong taboffset, start, end;
ulong firstxpart, nxtxpart;
int havedos, i, nplan9;
char name[10];
taboffset = 0;
dp = (Dospart*)&mbrbuf[0x1BE];
if(1) {
/* get the MBR (allowing for DMDDO) */
if(tsdbio(unit, &unit->part[0], mbrbuf, (vlong)taboffset*unit->secsize, 1) < 0)
return -1;
for(i=0; i<4; i++)
if(dp[i].type == DMDDO) {
if(trace)
print("DMDDO partition found\n");
taboffset = 63;
if(tsdbio(unit, &unit->part[0], mbrbuf, (vlong)taboffset*unit->secsize, 1) < 0)
return -1;
i = -1; /* start over */
}
}
/*
* Read the partitions, first from the MBR and then
* from successive extended partition tables.
*/
nplan9 = 0;
havedos = 0;
firstxpart = 0;
for(;;) {
if(tsdbio(unit, &unit->part[0], mbrbuf, (vlong)taboffset*unit->secsize, 1) < 0)
return -1;
if(trace) {
if(firstxpart)
print("%s ext %lud ", unit->name, taboffset);
else
print("%s mbr ", unit->name);
}
nxtxpart = 0;
for(i=0; i<4; i++) {
if(trace)
print("dp %d...", dp[i].type);
start = taboffset+GLONG(dp[i].start);
end = start+GLONG(dp[i].len);
if(dp[i].type == PLAN9) {
if(nplan9 == 0)
strcpy(name, "plan9");
else
sprint(name, "plan9.%d", nplan9);
sdaddpart(unit, name, start, end);
p9part(unit, name);
nplan9++;
}
/*
* We used to take the active partition (and then the first
* when none are active). We have to take the first here,
* so that the partition we call ``dos'' agrees with the
* partition disk/fdisk calls ``dos''.
*/
if(havedos==0 && isdos(dp[i].type)){
havedos = 1;
sdaddpart(unit, "dos", start, end);
}
/* nxtxpart is relative to firstxpart (or 0), not taboffset */
if(isextend(dp[i].type)){
nxtxpart = start-taboffset+firstxpart;
if(trace)
print("link %lud...", nxtxpart);
}
}
if(trace)
print("\n");
if(!nxtxpart)
break;
if(!firstxpart)
firstxpart = nxtxpart;
taboffset = nxtxpart;
}
return nplan9 ? 0 : -1;
}
/*
* To facilitate booting from CDs, we create a partition for
* the boot floppy image embedded in a bootable CD.
*/
static int
part9660(SDunit *unit)
{
uchar buf[2048];
ulong a, n;
uchar *p;
if(unit->secsize != 2048)
return -1;
if(sdbio(unit, &unit->part[0], buf, 2048, 17*2048) < 0)
return -1;
if(buf[0] || strcmp((char*)buf+1, "CD001\x01EL TORITO SPECIFICATION") != 0)
return -1;
p = buf+0x47;
a = p[0] | (p[1]<<8) | (p[2]<<16) | (p[3]<<24);
if(sdbio(unit, &unit->part[0], buf, 2048, a*2048) < 0)
return -1;
if(memcmp(buf, "\x01\x00\x00\x00", 4) != 0
|| memcmp(buf+30, "\x55\xAA", 2) != 0
|| buf[0x20] != 0x88)
return -1;
p = buf+0x28;
a = p[0] | (p[1]<<8) | (p[2]<<16) | (p[3]<<24);
switch(buf[0x21]){
case 0x01:
n = 1200*1024;
break;
case 0x02:
n = 1440*1024;
break;
case 0x03:
n = 2880*1024;
break;
default:
return -1;
}
n /= 2048;
print("found partition %s!cdboot; %lud+%lud\n", unit->name, a, n);
sdaddpart(unit, "cdboot", a, a+n);
return 0;
}
enum {
NEW = 1<<0,
OLD = 1<<1
};
void
partition(SDunit *unit)
{
int type;
char *p;
if(unit->part == 0)
return;
if(part9660(unit) == 0)
return;
p = getconf("partition");
if(p == nil)
p = defaultpartition;
if(p != nil && strncmp(p, "new", 3) == 0)
type = NEW;
else if(p != nil && strncmp(p, "old", 3) == 0)
type = OLD;
else
type = NEW|OLD;
if(nbuf < unit->secsize) {
free(mbrbuf);
free(partbuf);
mbrbuf = malloc(unit->secsize);
partbuf = malloc(unit->secsize);
if(mbrbuf==nil || partbuf==nil) {
free(mbrbuf);
free(partbuf);
partbuf = mbrbuf = nil;
nbuf = 0;
return;
}
nbuf = unit->secsize;
}
if((type & NEW) && mbrpart(unit) >= 0){
/* nothing to do */;
}
else if(type & OLD)
oldp9part(unit);
}