devcons.c

著名操作系统Plan 9的第三版的部分核心源代码。现在很难找到了。Plan 9是bell实验室开发的Unix后继者。

		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 Qkey:
		return keyread(buf, n, offset);

	case Qauth:
		return authread(c, cbuf, n);

	case Qauthcheck:
		return authcheckread(c, cbuf, n);

	case Qauthent:
		return authentread(c, cbuf, 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*8+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;
				*bp++ = '\n';
			}
		}
		n = readstr((ulong)offset, buf, n, b);
		free(b);
		return n;

	case Qswap:
		sprint(tmp, "%lud/%lud memory %lud/%lud swap\n",
			palloc.user-palloc.freecount,
			palloc.user, conf.nswap-swapalloc.free, conf.nswap);

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

	case Qsysname:
		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);
		n = readstr((ulong)offset, buf, n, b);
		free(b);
		return n;

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

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

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

	switch(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(a, 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){
				qlock(&kbd);
				if(kbd.x){
					qwrite(kbdq, kbd.line, kbd.x);
					kbd.x = 0;
				}
				kbd.raw = 1;
				qunlock(&kbd);
			} else if(strncmp(a, "rawoff", 6) == 0){
				kbd.raw = 0;
				kbd.x = 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 Qkey:
		return keywrite(a, n);

	case Qhostowner:
		return hostownerwrite(a, n);

	case Qhostdomain:
		return hostdomainwrite(a, n);

	case Quser:
		return userwrite(a, n);

	case Qauth:
		return authwrite(c, a, n);

	case Qauthcheck:
		return authcheck(c, a, n);

	case Qauthent:
		return authentwrite(c, a, n);

	case Qnull:
		break;

	case Qreboot:
		if(!iseve())
			error(Eperm);
		if(strncmp(a, "reboot", 6) == 0){
			print("conswrite: reboot\n");
			exit(0);
		}
		if(strncmp(a, "malloc", 6) == 0){	/* rsc bug */
			a = malloc(2);
			strcpy(a, "hi");
			free(a);
			a = malloc(2);
			strcpy(a, "helo");
			free(a);
			panic("not reached conswrite");
		}
		if(strncmp(a, "panic", 5) == 0)
			panic("/dev/reboot");
		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(cpuserver && !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 >= NAMELEN)
			error(Ebadarg);
		strncpy(sysname, a, n);
		sysname[n] = 0;
		if(sysname[n-1] == '\n')
			sysname[n-1] = 0;
		break;

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

void
setterm(char *f)
{
	char buf[2*NAMELEN];

	sprint(buf, f, conffile);
	ksetenv("terminal", buf);
}

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

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

struct Rb
{
	QLock;
	Rendez	producer;
	Rendez	consumer;
	ulong	randomcount;
	uchar	buf[1024];
	uchar	*ep;
	uchar	*rp;
	uchar	*wp;
	uchar	next;
	uchar	wakeme;
	ushort	bits;
	ulong	randn;
} rb;

static void
seedrand(void)
{
	randomread((void*)&rb.randn, sizeof(rb.randn));
}

int
nrand(int n)
{
	if(rb.randn == 0)
		seedrand();
	rb.randn = rb.randn*1103515245 + 12345 + MACHP(0)->ticks;
	return (rb.randn>>16) % n;
}

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


static int
rbnotfull(void*)
{
	int i;

	i = rb.rp - rb.wp;
	return i != 1 && i != (1 - sizeof(rb.buf));
}

static int
rbnotempty(void*)
{
	return rb.wp != rb.rp;
}

void
genrandom(void*)
{
	up->basepri = PriNormal;
	up->priority = up->basepri;

	for(;;){
		for(;;)
			if(++rb.randomcount > 100000)
				break;
		if(anyhigher())
			sched();
		if(!rbnotfull(0))
			sleep(&rb.producer, rbnotfull, 0);
	}
}

/*
 *  produce random bits in a circular buffer
 */
static void
randomclock(void)
{
	if(rb.randomcount == 0 || !rbnotfull(0))
		return;

	rb.bits = (rb.bits<<2) ^ rb.randomcount;
	rb.randomcount = 0;

	rb.next++;
	if(rb.next != 8/2)
		return;
	rb.next = 0;

	*rb.wp ^= rb.bits;
	if(rb.wp+1 == rb.ep)
		rb.wp = rb.buf;
	else
		rb.wp = rb.wp+1;

	if(rb.wakeme)
		wakeup(&rb.consumer);
}

static void
randominit(void)
{
	addclock0link(randomclock);
	rb.ep = rb.buf + sizeof(rb.buf);
	rb.rp = rb.wp = rb.buf;
	kproc("genrandom", genrandom, 0);
}

/*
 *  consume random bytes from a circular buffer
 */
static ulong
randomread(void *xp, ulong n)
{
	uchar *e, *p;
	ulong x;

	p = xp;

	if(waserror()){
		qunlock(&rb);
		nexterror();
	}

	qlock(&rb);
	for(e = p + n; p < e; ){
		if(rb.wp == rb.rp){
			rb.wakeme = 1;
			wakeup(&rb.producer);
			sleep(&rb.consumer, rbnotempty, 0);
			rb.wakeme = 0;
			continue;
		}

		/*
		 *  beating clocks will be precictable if
		 *  they are synchronized.  Use a cheap pseudo
		 *  random number generator to obscure any cycles.
		 */
		x = rb.randn*1103515245 ^ *rb.rp;
		*p++ = rb.randn = x;

		if(rb.rp+1 == rb.ep)
			rb.rp = rb.buf;
		else
			rb.rp = rb.rp+1;
	}
	qunlock(&rb);
	poperror();

	wakeup(&rb.producer);

	return n;
}

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+4];	// extra 4 bytes are null plus doprint
				// reserving space for a frigging UTF
				// char

	nsec = todget(&ticks);
	if(fasthz == 0LL)
		fastticks((uvlong*)&fasthz);
	sec = nsec/1000000000ULL;
	snprint(str, sizeof(str), "%*.0lud %*.0llud %*.0llud %*.0llud ",
		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;
}