devsd.c

在x86平台上运行不可信任代码的sandbox。

			return r;
		}
		i -= Qpart;
		if(unit->part == nil || i >= unit->npart){
			qunlock(&unit->ctl);
			decref(&sdev->r);
			break;
		}
		pp = &unit->part[i];
		if(!pp->valid){
			qunlock(&unit->ctl);
			decref(&sdev->r);
			return 0;
		}
		l = (pp->end - pp->start) * unit->secsize;
		mkqid(&q, QID(DEV(c->qid), UNIT(c->qid), i, Qpart),
			unit->vers+pp->vers, QTFILE);
		if(emptystr(pp->perm.user))
			kstrdup(&pp->perm.user, eve);
		devdir(c, q, pp->perm.name, l, pp->perm.user, pp->perm.perm, dp);
		qunlock(&unit->ctl);
		decref(&sdev->r);
		return 1;
	case Qraw:
	case Qctl:
	case Qpart:
		if((sdev = sdgetdev(DEV(c->qid))) == nil){
			devdir(c, q, "unavailable", 0, eve, 0, dp);
			return 1;
		}
		unit = sdev->unit[UNIT(c->qid)];
		qlock(&unit->ctl);
		r = sd2gen(c, TYPE(c->qid), dp);
		qunlock(&unit->ctl);
		decref(&sdev->r);
		return r;
	case Qtopctl:
		return sd1gen(c, TYPE(c->qid), dp);
	default:
		break;
	}

	return -1;
}

static Chan*
sdattach(char* spec)
{
	Chan *c;
	char *p;
	SDev *sdev;
	int idno, subno;

	if(*spec == '\0'){
		c = devattach(sddevtab.dc, spec);
		mkqid(&c->qid, QID(0, 0, 0, Qtopdir), 0, QTDIR);
		return c;
	}

	if(spec[0] != 's' || spec[1] != 'd')
		error(Ebadspec);
	idno = spec[2];
	subno = strtol(&spec[3], &p, 0);
	if(p == &spec[3])
		error(Ebadspec);

	if((sdev=sdgetdev(idno)) == nil)
		error(Enonexist);
	if(sdgetunit(sdev, subno) == nil){
		decref(&sdev->r);
		error(Enonexist);
	}

	c = devattach(sddevtab.dc, spec);
	mkqid(&c->qid, QID(sdev->idno, subno, 0, Qunitdir), 0, QTDIR);
	c->dev = (sdev->idno << UnitLOG) + subno;
	decref(&sdev->r);
	return c;
}

static Walkqid*
sdwalk(Chan* c, Chan* nc, char** name, int nname)
{
	return devwalk(c, nc, name, nname, nil, 0, sdgen);
}

static int
sdstat(Chan* c, uchar* db, int n)
{
	return devstat(c, db, n, nil, 0, sdgen);
}

static Chan*
sdopen(Chan* c, int omode)
{
	SDpart *pp;
	SDunit *unit;
	SDev *sdev;
	uchar tp;

	c = devopen(c, omode, 0, 0, sdgen);
	if((tp = TYPE(c->qid)) != Qctl && tp != Qraw && tp != Qpart)
		return c;

	sdev = sdgetdev(DEV(c->qid));
	if(sdev == nil)
		error(Enonexist);

	unit = sdev->unit[UNIT(c->qid)];

	switch(TYPE(c->qid)){
	case Qctl:
		c->qid.vers = unit->vers;
		break;
	case Qraw:
		c->qid.vers = unit->vers;
		if(tas(&unit->rawinuse) != 0){
			c->flag &= ~COPEN;
			decref(&sdev->r);
			error(Einuse);
		}
		unit->state = Rawcmd;
		break;
	case Qpart:
		qlock(&unit->ctl);
		if(waserror()){
			qunlock(&unit->ctl);
			c->flag &= ~COPEN;
			decref(&sdev->r);
			nexterror();
		}
		pp = &unit->part[PART(c->qid)];
		c->qid.vers = unit->vers+pp->vers;
		qunlock(&unit->ctl);
		poperror();
		break;
	}
	decref(&sdev->r);
	return c;
}

static void
sdclose(Chan* c)
{
	SDunit *unit;
	SDev *sdev;

	if(c->qid.type & QTDIR)
		return;
	if(!(c->flag & COPEN))
		return;

	switch(TYPE(c->qid)){
	default:
		break;
	case Qraw:
		sdev = sdgetdev(DEV(c->qid));
		if(sdev){
			unit = sdev->unit[UNIT(c->qid)];
			unit->rawinuse = 0;
			decref(&sdev->r);
		}
		break;
	}
}

static long
sdbio(Chan* c, int write, char* a, long len, uvlong off)
{
	int nchange;
	long l;
	uchar *b;
	SDpart *pp;
	SDunit *unit;
	SDev *sdev;
	ulong max, nb, offset;
	uvlong bno;

	sdev = sdgetdev(DEV(c->qid));
	if(sdev == nil){
		decref(&sdev->r);
		error(Enonexist);
	}
	unit = sdev->unit[UNIT(c->qid)];
	if(unit == nil)
		error(Enonexist);

	nchange = 0;
	qlock(&unit->ctl);
	while(waserror()){
		/* notification of media change; go around again */
		if(strcmp(up->errstr, Eio) == 0 && unit->sectors == 0 && nchange++ == 0){
			sdinitpart(unit);
			continue;
		}

		/* other errors; give up */
		qunlock(&unit->ctl);
		decref(&sdev->r);
		nexterror();
	}
	pp = &unit->part[PART(c->qid)];
	if(unit->vers+pp->vers != c->qid.vers)
		error(Echange);

	/*
	 * Check the request is within bounds.
	 * Removeable drives are locked throughout the I/O
	 * in case the media changes unexpectedly.
	 * Non-removeable drives are not locked during the I/O
	 * to allow the hardware to optimise if it can; this is
	 * a little fast and loose.
	 * It's assumed that non-removeable media parameters
	 * (sectors, secsize) can't change once the drive has
	 * been brought online.
	 */
	bno = (off/unit->secsize) + pp->start;
	nb = ((off+len+unit->secsize-1)/unit->secsize) + pp->start - bno;
	max = SDmaxio/unit->secsize;
	if(nb > max)
		nb = max;
	if(bno+nb > pp->end)
		nb = pp->end - bno;
	if(bno >= pp->end || nb == 0){
		if(write)
			error(Eio);
		qunlock(&unit->ctl);
		decref(&sdev->r);
		poperror();
		return 0;
	}
	if(!(unit->inquiry[1] & 0x80)){
		qunlock(&unit->ctl);
		poperror();
	}

	b = sdmalloc(nb*unit->secsize);
	if(b == nil)
		error(Enomem);
	if(waserror()){
		sdfree(b);
		if(!(unit->inquiry[1] & 0x80))
			decref(&sdev->r);		/* gadverdamme! */
		nexterror();
	}

	offset = off%unit->secsize;
	if(offset+len > nb*unit->secsize)
		len = nb*unit->secsize - offset;
	if(write){
		if(offset || (len%unit->secsize)){
			l = unit->dev->ifc->bio(unit, 0, 0, b, nb, bno);
			if(l < 0)
				error(Eio);
			if(l < (nb*unit->secsize)){
				nb = l/unit->secsize;
				l = nb*unit->secsize - offset;
				if(len > l)
					len = l;
			}
		}
		memmove(b+offset, a, len);
		l = unit->dev->ifc->bio(unit, 0, 1, b, nb, bno);
		if(l < 0)
			error(Eio);
		if(l < offset)
			len = 0;
		else if(len > l - offset)
			len = l - offset;
	}
	else{
		l = unit->dev->ifc->bio(unit, 0, 0, b, nb, bno);
		if(l < 0)
			error(Eio);
		if(l < offset)
			len = 0;
		else if(len > l - offset)
			len = l - offset;
		memmove(a, b+offset, len);
	}
	sdfree(b);
	poperror();

	if(unit->inquiry[1] & 0x80){
		qunlock(&unit->ctl);
		poperror();
	}

	decref(&sdev->r);
	return len;
}

static long
sdrio(SDreq* r, void* a, long n)
{
	void *data;

	if(n >= SDmaxio || n < 0)
		error(Etoobig);

	data = nil;
	if(n){
		if((data = sdmalloc(n)) == nil)
			error(Enomem);
		if(r->write)
			memmove(data, a, n);
	}
	r->data = data;
	r->dlen = n;

	if(waserror()){
		sdfree(data);
		r->data = nil;
		nexterror();
	}

	if(r->unit->dev->ifc->rio(r) != SDok)
		error(Eio);

	if(!r->write && r->rlen > 0)
		memmove(a, data, r->rlen);
	sdfree(data);
	r->data = nil;
	poperror();

	return r->rlen;
}

/*
 * SCSI simulation for non-SCSI devices
 */
int
sdsetsense(SDreq *r, int status, int key, int asc, int ascq)
{
	int len;
	SDunit *unit;

	unit = r->unit;
	unit->sense[2] = key;
	unit->sense[12] = asc;
	unit->sense[13] = ascq;

	r->status = status;
	if(status == SDcheck && !(r->flags & SDnosense)){
		/* request sense case from sdfakescsi */
		len = sizeof unit->sense;
		if(len > sizeof r->sense-1)
			len = sizeof r->sense-1;
		memmove(r->sense, unit->sense, len);
		unit->sense[2] = 0;
		unit->sense[12] = 0;
		unit->sense[13] = 0;
		r->flags |= SDvalidsense;
		return SDok;
	}
	return status;
}

int
sdmodesense(SDreq *r, uchar *cmd, void *info, int ilen)
{
	int len;
	uchar *data;

	/*
	 * Fake a vendor-specific request with page code 0,
	 * return the drive info.
	 */
	if((cmd[2] & 0x3F) != 0 && (cmd[2] & 0x3F) != 0x3F)
		return sdsetsense(r, SDcheck, 0x05, 0x24, 0);
	len = (cmd[7]<<8)|cmd[8];
	if(len == 0)
		return SDok;
	if(len < 8+ilen)
		return sdsetsense(r, SDcheck, 0x05, 0x1A, 0);
	if(r->data == nil || r->dlen < len)
		return sdsetsense(r, SDcheck, 0x05, 0x20, 1);
	data = r->data;
	memset(data, 0, 8);
	data[0] = ilen>>8;
	data[1] = ilen;
	if(ilen)
		memmove(data+8, info, ilen);
	r->rlen = 8+ilen;
	return sdsetsense(r, SDok, 0, 0, 0);
}

int
sdfakescsi(SDreq *r, void *info, int ilen)
{
	uchar *cmd, *p;
	uvlong len;
	SDunit *unit;

	cmd = r->cmd;
	r->rlen = 0;
	unit = r->unit;

	/*
	 * Rewrite read(6)/write(6) into read(10)/write(10).
	 */
	switch(cmd[0]){
	case 0x08:	/* read */
	case 0x0A:	/* write */
		cmd[9] = 0;
		cmd[8] = cmd[4];
		cmd[7] = 0;
		cmd[6] = 0;
		cmd[5] = cmd[3];
		cmd[4] = cmd[2];
		cmd[3] = cmd[1] & 0x0F;
		cmd[2] = 0;
		cmd[1] &= 0xE0;
		cmd[0] |= 0x20;
		break;
	}

	/*
	 * Map SCSI commands into ATA commands for discs.
	 * Fail any command with a LUN except INQUIRY which
	 * will return 'logical unit not supported'.
	 */
	if((cmd[1]>>5) && cmd[0] != 0x12)
		return sdsetsense(r, SDcheck, 0x05, 0x25, 0);

	switch(cmd[0]){
	default:
		return sdsetsense(r, SDcheck, 0x05, 0x20, 0);

	case 0x00:	/* test unit ready */
		return sdsetsense(r, SDok, 0, 0, 0);

	case 0x03:	/* request sense */
		if(cmd[4] < sizeof unit->sense)
			len = cmd[4];
		else
			len = sizeof unit->sense;
		if(r->data && r->dlen >= len){
			memmove(r->data, unit->sense, len);
			r->rlen = len;
		}
		return sdsetsense(r, SDok, 0, 0, 0);

	case 0x12:	/* inquiry */
		if(cmd[4] < sizeof unit->inquiry)
			len = cmd[4];
		else
			len = sizeof unit->inquiry;
		if(r->data && r->dlen >= len){
			memmove(r->data, unit->inquiry, len);
			r->rlen = len;
		}
		return sdsetsense(r, SDok, 0, 0, 0);

	case 0x1B:	/* start/stop unit */
		/*
		 * nop for now, can use power management later.
		 */
		return sdsetsense(r, SDok, 0, 0, 0);

	case 0x25:	/* read capacity */
		if((cmd[1] & 0x01) || cmd[2] || cmd[3])
			return sdsetsense(r, SDcheck, 0x05, 0x24, 0);
		if(r->data == nil || r->dlen < 8)
			return sdsetsense(r, SDcheck, 0x05, 0x20, 1);

		/*
		 * Read capacity returns the LBA of the last sector.
		 */
		len = unit->sectors - 1;
		p = r->data;
		*p++ = len>>24;
		*p++ = len>>16;
		*p++ = len>>8;
		*p++ = len;
		len = 512;
		*p++ = len>>24;
		*p++ = len>>16;
		*p++ = len>>8;
		*p++ = len;
		r->rlen = p - (uchar*)r->data;
		return sdsetsense(r, SDok, 0, 0, 0);

	case 0x9E:	/* long read capacity */
		if((cmd[1] & 0x01) || cmd[2] || cmd[3])
			return sdsetsense(r, SDcheck, 0x05, 0x24, 0);
		if(r->data == nil || r->dlen < 8)
			return sdsetsense(r, SDcheck, 0x05, 0x20, 1);
		/*
		 * Read capcity returns the LBA of the last sector.
		 */
		len = unit->sectors - 1;
		p = r->data;
		*p++ = len>>56;
		*p++ = len>>48;
		*p++ = len>>40;
		*p++ = len>>32;
		*p++ = len>>24;
		*p++ = len>>16;
		*p++ = len>>8;
		*p++ = len;
		len = 512;
		*p++ = len>>24;
		*p++ = len>>16;
		*p++ = len>>8;
		*p++ = len;
		r->rlen = p - (uchar*)r->data;
		return sdsetsense(r, SDok, 0, 0, 0);

	case 0x5A:	/* mode sense */
		return sdmodesense(r, cmd, info, ilen);

	case 0x28:	/* read */
	case 0x2A:	/* write */
	case 0x88:	/* read16 */
	case 0x8a:	/* write16 */
		return SDnostatus;
	}
}

static long
sdread(Chan *c, void *a, long n, vlong off)
{
	char *p, *e, *buf;
	SDpart *pp;
	SDunit *unit;
	SDev *sdev;
	ulong offset;
	int i, l, m, status;

	offset = off;
	switch(TYPE(c->qid)){
	default:
		error(Eperm);
	case Qtopctl:
		m = 64*1024;	/* room for register dumps */
		p = buf = malloc(m);
		assert(p);
		e = p + m;
		qlock(&devslock);
		for(i = 0; i < nelem(devs); i++){
			sdev = devs[i];
			if(sdev && sdev->ifc->rtopctl)
				p = sdev->ifc->rtopctl(sdev, p, e);
		}
		qunlock(&devslock);
		n = readstr(off, a, n, buf);
		free(buf);