devcons.c

在x86平台上运行不可信任代码的sandbox。

	randominit();
#if 0 // Plan 9 VX
	/*
	 * at 115200 baud, the 1024 char buffer takes 56 ms to process,
	 * processing it every 22 ms should be fine
	 */
	addclock0link(kbdputcclock, 22);
#endif
}

static Chan*
consattach(char *spec)
{
	return devattach('c', spec);
}

static Walkqid*
conswalk(Chan *c, Chan *nc, char **name, int nname)
{
	return devwalk(c, nc, name,nname, consdir, nelem(consdir), devgen);
}

static int
consstat(Chan *c, uchar *dp, int n)
{
	return devstat(c, dp, n, consdir, nelem(consdir), devgen);
}

static Chan*
consopen(Chan *c, int omode)
{
	c->aux = nil;
	c = devopen(c, omode, consdir, nelem(consdir), devgen);
	switch((ulong)c->qid.path){
	case Qconsctl:
		incref(&kbd.ctl);
		break;

	case Qkprint:
		if(tas(&kprintinuse) != 0){
			c->flag &= ~COPEN;
			error(Einuse);
		}
		if(kprintoq == nil){
			kprintoq = qopen(8*1024, Qcoalesce, 0, 0);
			if(kprintoq == nil){
				c->flag &= ~COPEN;
				error(Enomem);
			}
			qnoblock(kprintoq, 1);
		}else
			qreopen(kprintoq);
		c->iounit = qiomaxatomic;
		break;
	}
	return c;
}

static void
consclose(Chan *c)
{
	switch((ulong)c->qid.path){
	/* last close of control file turns off raw */
	case Qconsctl:
		if(c->flag&COPEN){
			if(decref(&kbd.ctl) == 0)
				kbd.raw = 0;
		}
		break;

	/* close of kprint allows other opens */
	case Qkprint:
		if(c->flag & COPEN){
			kprintinuse = 0;
			qhangup(kprintoq, nil);
		}
		break;
	}
}

static long
consread(Chan *c, void *buf, long n, vlong off)
{
	ulong l;
	Mach *mp;
	char *b, *bp, ch;
	char tmp[256];		/* must be >= 18*NUMSIZE (Qswap) */
	int i, k, id, send;
	vlong offset = off;

	if(n <= 0)
		return n;

	switch((ulong)c->qid.path){
	case Qdir:
		return devdirread(c, buf, n, consdir, nelem(consdir), devgen);

	case Qcons:
		qlock(&kbd.lk);
		if(waserror()) {
			qunlock(&kbd.lk);
			nexterror();
		}
		while(!qcanread(lineq)){
			if(qread(kbdq, &ch, 1) == 0)
				continue;
			send = 0;
			if(ch == 0){
				/* flush output on rawoff -> rawon */
				if(kbd.x > 0)
					send = !qcanread(kbdq);
			}else if(kbd.raw){
				kbd.line[kbd.x++] = ch;
				send = !qcanread(kbdq);
			}else{
				switch(ch){
				case '\b':
					if(kbd.x > 0)
						kbd.x--;
					break;
				case 0x15:	/* ^U */
					kbd.x = 0;
					break;
				case '\n':
				case 0x04:	/* ^D */
					send = 1;
				default:
					if(ch != 0x04)
						kbd.line[kbd.x++] = ch;
					break;
				}
			}
			if(send || kbd.x == sizeof kbd.line){
				qwrite(lineq, kbd.line, kbd.x);
				kbd.x = 0;
			}
		}
		n = qread(lineq, buf, n);
		qunlock(&kbd.lk);
		poperror();
		return n;

	case Qcputime:
		k = offset;
		if(k >= 6*NUMSIZE)
			return 0;
		if(k+n > 6*NUMSIZE)
			n = 6*NUMSIZE - k;
		/* easiest to format in a separate buffer and copy out */
		for(i=0; i<6 && NUMSIZE*i<k+n; i++){
			l = up->time[i];
			if(i == TReal)
				l = msec() - l;
			l = TK2MS(l);
			readnum(0, tmp+NUMSIZE*i, NUMSIZE, l, NUMSIZE);
		}
		memmove(buf, tmp+k, n);
		return n;

	case Qkmesg:
		/*
		 * This is unlocked to avoid tying up a process
		 * that's writing to the buffer.  kmesg.n never 
		 * gets smaller, so worst case the reader will
		 * see a slurred buffer.
		 */
		if(off >= kmesg.n)
			n = 0;
		else{
			if(off+n > kmesg.n)
				n = kmesg.n - off;
			memmove(buf, kmesg.buf+off, n);
		}
		return n;
		
	case Qkprint:
		return qread(kprintoq, buf, n);

	case Qpgrpid:
		return readnum((ulong)offset, buf, n, up->pgrp->pgrpid, NUMSIZE);

	case Qpid:
		return readnum((ulong)offset, buf, n, up->pid, NUMSIZE);

	case Qppid:
		return readnum((ulong)offset, buf, n, up->parentpid, NUMSIZE);

	case Qtime:
		return readtime((ulong)offset, buf, n);

	case Qbintime:
		return readbintime(buf, n);

	case Qhostowner:
		return readstr((ulong)offset, buf, n, eve);

	case Qhostdomain:
		return readstr((ulong)offset, buf, n, hostdomain);

	case Quser:
		return readstr((ulong)offset, buf, n, up->user);

	case Qnull:
		return 0;

	case Qsysstat:
		b = smalloc(conf.nmach*(NUMSIZE*11+1) + 1);	/* +1 for NUL */
		bp = b;
		for(id = 0; id < 32; id++) {
			if(active.machs & (1<<id)) {
				mp = MACHP(id);
				readnum(0, bp, NUMSIZE, id, NUMSIZE);
				bp += NUMSIZE;
				readnum(0, bp, NUMSIZE, mp->cs, NUMSIZE);
				bp += NUMSIZE;
				readnum(0, bp, NUMSIZE, mp->intr, NUMSIZE);
				bp += NUMSIZE;
				readnum(0, bp, NUMSIZE, mp->syscall, NUMSIZE);
				bp += NUMSIZE;
				readnum(0, bp, NUMSIZE, mp->pfault, NUMSIZE);
				bp += NUMSIZE;
				readnum(0, bp, NUMSIZE, mp->tlbfault, NUMSIZE);
				bp += NUMSIZE;
				readnum(0, bp, NUMSIZE, mp->tlbpurge, NUMSIZE);
				bp += NUMSIZE;
				readnum(0, bp, NUMSIZE, mp->load, NUMSIZE);
				bp += NUMSIZE;
				readnum(0, bp, NUMSIZE,
					(mp->perf.avg_inidle*100)/mp->perf.period,
					NUMSIZE);
				bp += NUMSIZE;
				readnum(0, bp, NUMSIZE,
					(mp->perf.avg_inintr*100)/mp->perf.period,
					NUMSIZE);
				bp += NUMSIZE;
				*bp++ = '\n';
			}
		}
		if(waserror()){
			free(b);
			nexterror();
		}
		n = readstr((ulong)offset, buf, n, b);
		free(b);
		poperror();
		return n;

	case Qswap:
		tmp[0] = 0;

		return readstr((ulong)offset, buf, n, tmp);

	case Qsysname:
		if(sysname == nil)
			return 0;
		return readstr((ulong)offset, buf, n, sysname);

	case Qrandom:
		return randomread(buf, n);

	case Qdrivers:
		b = malloc(READSTR);
		if(b == nil)
			error(Enomem);
		n = 0;
		for(i = 0; devtab[i] != nil; i++)
			n += snprint(b+n, READSTR-n, "#%C %s\n", devtab[i]->dc,  devtab[i]->name);
		if(waserror()){
			free(b);
			nexterror();
		}
		n = readstr((ulong)offset, buf, n, b);
		free(b);
		poperror();
		return n;

	case Qzero:
		memset(buf, 0, n);
		return n;

	case Qosversion:
		snprint(tmp, sizeof tmp, "2000");
		n = readstr((ulong)offset, buf, n, tmp);
		return n;

	default:
		print("consread 0x%llux\n", c->qid.path);
		error(Egreg);
	}
	return -1;		/* never reached */
}

static long
conswrite(Chan *c, void *va, long n, vlong off)
{
	char buf[256], ch;
	long l, bp;
	char *a;
	Mach *mp;
	int id, fd;
	Chan *swc;
	ulong offset;
	Cmdbuf *cb;
	Cmdtab *ct;

	a = va;
	offset = off;

	switch((ulong)c->qid.path){
	case Qcons:
		/*
		 * Can't page fault in putstrn, so copy the data locally.
		 */
		l = n;
		while(l > 0){
			bp = l;
			if(bp > sizeof buf)
				bp = sizeof buf;
			memmove(buf, a, bp);
			putstrn0(buf, bp, 1);
			a += bp;
			l -= bp;
		}
		break;

	case Qconsctl:
		if(n >= sizeof(buf))
			n = sizeof(buf)-1;
		strncpy(buf, a, n);
		buf[n] = 0;
		for(a = buf; a;){
			if(strncmp(a, "rawon", 5) == 0){
				kbd.raw = 1;
				/* clumsy hack - wake up reader */
				ch = 0;
				qwrite(kbdq, &ch, 1);			
			} else if(strncmp(a, "rawoff", 6) == 0){
				kbd.raw = 0;
			} else if(strncmp(a, "ctlpon", 6) == 0){
				kbd.ctlpoff = 0;
			} else if(strncmp(a, "ctlpoff", 7) == 0){
				kbd.ctlpoff = 1;
			}
			if((a = strchr(a, ' ')))
				a++;
		}
		break;

	case Qtime:
		if(!iseve())
			error(Eperm);
		return writetime(a, n);

	case Qbintime:
		if(!iseve())
			error(Eperm);
		return writebintime(a, n);

	case Qhostowner:
		return hostownerwrite(a, n);

	case Qhostdomain:
		return hostdomainwrite(a, n);

	case Quser:
		return userwrite(a, n);

	case Qnull:
		break;

	case Qreboot:
		if(!iseve())
			error(Eperm);
		cb = parsecmd(a, n);

		if(waserror()) {
			free(cb);
			nexterror();
		}
		ct = lookupcmd(cb, rebootmsg, nelem(rebootmsg));
		switch(ct->index) {
		case CMhalt:
			reboot(nil, 0, 0);
			break;
		case CMreboot:
			rebootcmd(cb->nf-1, cb->f+1);
			break;
		case CMpanic:
			*(ulong*)0=0;
			panic("/dev/reboot");
		}
		poperror();
		free(cb);
		break;

	case Qsysstat:
		for(id = 0; id < 32; id++) {
			if(active.machs & (1<<id)) {
				mp = MACHP(id);
				mp->cs = 0;
				mp->intr = 0;
				mp->syscall = 0;
				mp->pfault = 0;
				mp->tlbfault = 0;
				mp->tlbpurge = 0;
			}
		}
		break;

	case Qswap:
		if(n >= sizeof buf)
			error(Egreg);
		memmove(buf, va, n);	/* so we can NUL-terminate */
		buf[n] = 0;
		/* start a pager if not already started */
		if(strncmp(buf, "start", 5) == 0){
			kickpager();
			break;
		}
		if(!iseve())
			error(Eperm);
		if(buf[0]<'0' || '9'<buf[0])
			error(Ebadarg);
		fd = strtoul(buf, 0, 0);
		swc = fdtochan(fd, -1, 1, 1);
		setswapchan(swc);
		break;

	case Qsysname:
		if(offset != 0)
			error(Ebadarg);
		if(n <= 0 || n >= sizeof buf)
			error(Ebadarg);
		strncpy(buf, a, n);
		buf[n] = 0;
		if(buf[n-1] == '\n')
			buf[n-1] = 0;
		kstrdup(&sysname, buf);
		break;

	default:
		print("conswrite: 0x%llux\n", c->qid.path);
		error(Egreg);
	}
	return n;
}

Dev consdevtab = {
	'c',
	"cons",

	devreset,
	consinit,
	devshutdown,
	consattach,
	conswalk,
	consstat,
	consopen,
	devcreate,
	consclose,
	consread,
	devbread,
	conswrite,
	devbwrite,
	devremove,
	devwstat,
};

static	ulong	randn;

static void
seedrand(void)
{
	if(!waserror()){
		randomread((void*)&randn, sizeof(randn));
		poperror();
	}
}

int
nrand(int n)
{
	if(randn == 0)
		seedrand();
	randn = randn*1103515245 + 12345 + msec();
	return (randn>>16) % n;
}

int
rand(void)
{
	nrand(1);
	return randn;
}

static uvlong uvorder = 0x0001020304050607ULL;

static uchar*
le2vlong(vlong *to, uchar *f)
{
	uchar *t, *o;
	int i;

	t = (uchar*)to;
	o = (uchar*)&uvorder;
	for(i = 0; i < sizeof(vlong); i++)
		t[o[i]] = f[i];
	return f+sizeof(vlong);
}

static uchar*
vlong2le(uchar *t, vlong from)
{
	uchar *f, *o;
	int i;

	f = (uchar*)&from;
	o = (uchar*)&uvorder;
	for(i = 0; i < sizeof(vlong); i++)
		t[i] = f[o[i]];
	return t+sizeof(vlong);
}

static long order = 0x00010203;

static uchar*
le2long(long *to, uchar *f)
{
	uchar *t, *o;
	int i;

	t = (uchar*)to;
	o = (uchar*)&order;
	for(i = 0; i < sizeof(long); i++)
		t[o[i]] = f[i];
	return f+sizeof(long);
}

/*static*/ uchar*
long2le(uchar *t, long from)
{
	uchar *f, *o;
	int i;

	f = (uchar*)&from;
	o = (uchar*)&order;
	for(i = 0; i < sizeof(long); i++)
		t[i] = f[o[i]];
	return t+sizeof(long);
}

char *Ebadtimectl = "bad time control";

/*
 *  like the old #c/time but with added info.  Return
 *
 *	secs	nanosecs	fastticks	fasthz
 */
static int
readtime(ulong off, char *buf, int n)
{
	vlong	nsec, ticks;
	long sec;
	char str[7*NUMSIZE];

	nsec = todget(&ticks);
	if(fasthz == 0LL)
		fastticks((uvlong*)&fasthz);
	sec = nsec/1000000000ULL;
	snprint(str, sizeof(str), "%*lud %*llud %*llud %*llud ",
		NUMSIZE-1, sec,
		VLNUMSIZE-1, nsec,
		VLNUMSIZE-1, ticks,
		VLNUMSIZE-1, fasthz);
	return readstr(off, buf, n, str);
}

/*
 *  set the time in seconds
 */
static int
writetime(char *buf, int n)
{
	char b[13];
	long i;
	vlong now;

	if(n >= sizeof(b))
		error(Ebadtimectl);
	strncpy(b, buf, n);
	b[n] = 0;
	i = strtol(b, 0, 0);
	if(i <= 0)
		error(Ebadtimectl);
	now = i*1000000000LL;
	todset(now, 0, 0);
	return n;
}

/*
 *  read binary time info.  all numbers are little endian.
 *  ticks and nsec are syncronized.
 */
static int
readbintime(char *buf, int n)
{
	int i;
	vlong nsec, ticks;
	uchar *b = (uchar*)buf;

	i = 0;
	if(fasthz == 0LL)
		fastticks((uvlong*)&fasthz);
	nsec = todget(&ticks);
	if(n >= 3*sizeof(uvlong)){
		vlong2le(b+2*sizeof(uvlong), fasthz);
		i += sizeof(uvlong);
	}
	if(n >= 2*sizeof(uvlong)){
		vlong2le(b+sizeof(uvlong), ticks);
		i += sizeof(uvlong);
	}
	if(n >= 8){
		vlong2le(b, nsec);
		i += sizeof(vlong);
	}
	return i;
}

/*
 *  set any of the following
 *	- time in nsec
 *	- nsec trim applied over some seconds
 *	- clock frequency
 */
static int
writebintime(char *buf, int n)
{
	uchar *p;
	vlong delta;
	long period;

	n--;
	p = (uchar*)buf + 1;
	switch(*buf){
	case 'n':
		if(n < sizeof(vlong))
			error(Ebadtimectl);
		le2vlong(&delta, p);
		todset(delta, 0, 0);
		break;
	case 'd':
		if(n < sizeof(vlong)+sizeof(long))
			error(Ebadtimectl);
		p = le2vlong(&delta, p);
		le2long(&period, p);
		todset(-1, delta, period);
		break;
	case 'f':
		if(n < sizeof(uvlong))
			error(Ebadtimectl);
		le2vlong(&fasthz, p);
		todsetfreq(fasthz);
		break;
	}
	return n;
}

// Plan 9 VX
int
tailkmesg(char *a, int n)
{
	ilock(&kmesg.lk);
	if(n > kmesg.n)
		n = kmesg.n;
	memmove(a, kmesg.buf+kmesg.n-n, n);
	iunlock(&kmesg.lk);
	return n;
}