/*
* 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(PSDunit *unit)
{
Dospart *dp;
uvlong taboffset, start, end;
uvlong firstxpart, nxtxpart;
int havedos, i, nplan9;
char name[10];
taboffset = 0;
dp = (Dospart*)&mbrbuf[0x1BE];
{
/* get the MBR (allowing for DMDDO) */
if(sdreadblk(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(sdreadblk(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(sdreadblk(unit, &unit->part[0], mbrbuf,
(vlong)taboffset * unit->secsize, 1) < 0)
return -1;
if(Trace) {
if(firstxpart)
print("%s ext %llud ", 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)
strncpy(name, "plan9", sizeof name);
else
snprint(name, sizeof name, "plan9.%d",
nplan9);
psdaddpart(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;
psdaddpart(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 %llud...", nxtxpart);
}
}
if(Trace)
print("\n");
if(!nxtxpart)
break;
if(!firstxpart)
firstxpart = nxtxpart;
taboffset = nxtxpart;
}
return nplan9 ? 0 : -1;
}
int
mbrpart(Disk *d)
{
uchar mbrbuf[512];
char name[10];
Dospart *dp;
ulong taboffset, start, end;
ulong firstxpart, nxtxpart;
int i, nplan9, havedos;
#define readmbr() \
if(readdisk(d, mbrbuf, (uvlong)taboffset*512, sizeof mbrbuf) == -1 \
|| mbrbuf[0x1FE] != 0x55 || mbrbuf[0x1FF] != 0xAA) \
return 0
if(d->secsize > 512)
return 0;
dp = (Dospart*)&mbrbuf[0x1BE];
taboffset = 0;
if(1) {
/* get the MBR (allowing for DMDDO) */
readmbr();
for(i = 0; i < 4; i++) {
if(dp[i].type == DMDDO) {
taboffset = 63;
readmbr();
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(;;) {
readmbr();
nxtxpart = 0;
for(i = 0; i < 4; i++) {
/* partition offsets are relative to taboffset */
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);
addpart(d, name, start, end);
p9part(d, name, start);
nplan9++;
}
if(!havedos && isdos(dp[i].type)) {
havedos = 1;
addpart(d, "dos", start, end);
}
/* nxtxpart is relative to firstxpart (or 0), not taboffset */
if(isextend(dp[i].type))
nxtxpart = start-taboffset+firstxpart;
}
if(!nxtxpart)
break;
if(!firstxpart)
firstxpart = nxtxpart;
taboffset = nxtxpart;
}
return nplan9 + havedos;
}
