devcons.c

在x86平台上运行不可信任代码的sandbox。

#include	"u.h"
#include	"lib.h"
#include	"mem.h"
#include	"dat.h"
#include	"fns.h"
#include	"error.h"

#include "authsrv.h"

void	(*consdebug)(void) = nil;
void	(*screenputs)(char*, int) = nil;

Queue*	kbdq;			/* unprocessed console input */
Queue*	lineq;			/* processed console input */
Queue*	kprintoq;		/* console output, for /dev/kprint */
ulong	kprintinuse;		/* test and set whether /dev/kprint is open */
int	iprintscreenputs = 1;

int	panicking;

static struct
{
	QLock lk;

	int	raw;		/* true if we shouldn't process input */
	Ref	ctl;		/* number of opens to the control file */
	int	x;		/* index into line */
	char	line[1024];	/* current input line */

	int	count;
	int	ctlpoff;

	/* a place to save up characters at interrupt time before dumping them in the queue */
	Lock	lockputc;
	char	istage[1024];
	char	*iw;
	char	*ir;
	char	*ie;
} kbd = {
	.iw	= kbd.istage,
	.ir	= kbd.istage,
	.ie	= kbd.istage + sizeof(kbd.istage),
};

char	*sysname;
vlong	fasthz = 1000000000ULL;  // Plan 9 VX = nsecs

static void	seedrand(void);
static int	readtime(ulong, char*, int);
static int	readbintime(char*, int);
static int	writetime(char*, int);
static int	writebintime(char*, int);

enum
{
	CMhalt,
	CMreboot,
	CMpanic,
};

Cmdtab rebootmsg[] =
{
	CMhalt,		"halt",		1,
	CMreboot,	"reboot",	0,
	CMpanic,	"panic",	0,
};

void
printinit(void)
{
	lineq = qopen(2*1024, 0, nil, nil);
	if(lineq == nil)
		panic("printinit");
	qnoblock(lineq, 1);
}

#if 0 // Plan 9 VX
int
consactive(void)
{
	if(serialoq)
		return qlen(serialoq) > 0;
	return 0;
}
#endif

#if 0 // Plan 9 VX
void
prflush(void)
{
	ulong now;

	now = m->ticks;
	while(consactive())
		if(m->ticks - now >= HZ)
			break;
}
#endif

/*
 * Log console output so it can be retrieved via /dev/kmesg.
 * This is good for catching boot-time messages after the fact.
 */
struct {
	Lock lk;
	char buf[16384];
	uint n;
} kmesg;

static void
kmesgputs(char *str, int n)
{
	uint nn, d;

	ilock(&kmesg.lk);
	/* take the tail of huge writes */
	if(n > sizeof kmesg.buf){
		d = n - sizeof kmesg.buf;
		str += d;
		n -= d;
	}

	/* slide the buffer down to make room */
	nn = kmesg.n;
	if(nn + n >= sizeof kmesg.buf){
		d = nn + n - sizeof kmesg.buf;
		if(d)
			memmove(kmesg.buf, kmesg.buf+d, sizeof kmesg.buf-d);
		nn -= d;
	}

	/* copy the data in */
	memmove(kmesg.buf+nn, str, n);
	nn += n;
	kmesg.n = nn;
	iunlock(&kmesg.lk);
}

/*
 *   Print a string on the console.  Convert \n to \r\n for serial
 *   line consoles.  Locking of the queues is left up to the screen
 *   or uart code.  Multi-line messages to serial consoles may get
 *   interspersed with other messages.
 */
static void
putstrn0(char *str, int n, int usewrite)
{

	if(!islo())
		usewrite = 0;

	/*
	 *  how many different output devices do we need?
	 */
	kmesgputs(str, n);

	/*
	 *  if someone is reading /dev/kprint,
	 *  put the message there.
	 *  if not and there's an attached bit mapped display,
	 *  put the message there.
	 *
	 *  if there's a serial line being used as a console,
	 *  put the message there.
	 */
	if(kprintoq != nil && !qisclosed(kprintoq)){
		if(usewrite)
			qwrite(kprintoq, str, n);
		else
			qiwrite(kprintoq, str, n);
	}else if(screenputs != nil)
		screenputs(str, n);

	uartputs(str, n);
#if 0 // Plan 9 VX
	if(serialoq == nil){
		uartputs(str, n);
		return;
	}

	while(n > 0) {
		t = memchr(str, '\n', n);
		if(t && !kbd.raw) {
			m = t-str;
			if(usewrite){
				qwrite(serialoq, str, m);
				qwrite(serialoq, "\r\n", 2);
			} else {
				qiwrite(serialoq, str, m);
				qiwrite(serialoq, "\r\n", 2);
			}
			n -= m+1;
			str = t+1;
		} else {
			if(usewrite)
				qwrite(serialoq, str, n);
			else
				qiwrite(serialoq, str, n);
			break;
		}
	}
#endif
}

void
putstrn(char *str, int n)
{
	putstrn0(str, n, 0);
}

int noprint;

int
print(char *fmt, ...)
{
	int n;
	va_list arg;
	char buf[PRINTSIZE];

	if(noprint)
		return -1;

	va_start(arg, fmt);
	n = vseprint(buf, buf+sizeof(buf), fmt, arg) - buf;
	va_end(arg);
	putstrn(buf, n);

	return n;
}

/*
 * Want to interlock iprints to avoid interlaced output on 
 * multiprocessor, but don't want to deadlock if one processor
 * dies during print and another has something important to say.
 * Make a good faith effort.
 */
#if 0 // Plan 9 VX
static Lock iprintlock;
static int
iprintcanlock(Lock *l)
{
	int i;
	
	for(i=0; i<1000; i++){
		if(canlock(l))
			return 1;
		if(l->m == MACHP(m->machno))
			return 0;
		microdelay(100);
	}
	return 0;
}

int
iprint(char *fmt, ...)
{
	int n, s, locked;
	va_list arg;
	char buf[PRINTSIZE];

	s = splhi();
	va_start(arg, fmt);
	n = vseprint(buf, buf+sizeof(buf), fmt, arg) - buf;
	va_end(arg);
	locked = iprintcanlock(&iprintlock);
	if(screenputs != nil && iprintscreenputs)
		screenputs(buf, n);
	uartputs(buf, n);
	if(locked)
		unlock(&iprintlock);
	splx(s);

	return n;
}

void
panic(char *fmt, ...)
{
	int n, s;
	va_list arg;
	char buf[PRINTSIZE];

	kprintoq = nil;	/* don't try to write to /dev/kprint */

	if(panicking)
		for(;;);
	panicking = 1;

	s = splhi();
	strcpy(buf, "panic: ");
	va_start(arg, fmt);
	n = vseprint(buf+strlen(buf), buf+sizeof(buf), fmt, arg) - buf;
	va_end(arg);
	iprint("%s\n", buf);
	if(consdebug)
		(*consdebug)();
	splx(s);
	prflush();
	buf[n] = '\n';
	putstrn(buf, n+1);
	dumpstack();

	exit(1);
}

/* libmp at least contains a few calls to sysfatal; simulate with panic */
void
sysfatal(char *fmt, ...)
{
	char err[256];
	va_list arg;

	va_start(arg, fmt);
	vseprint(err, err + sizeof err, fmt, arg);
	va_end(arg);
	panic("sysfatal: %s", err);
}

void
_assert(char *fmt)
{
	panic("assert failed at 0x%lux: %s", getcallerpc(&fmt), fmt);
}
#endif

int
pprint(char *fmt, ...)
{
	int n;
	Chan *c;
	va_list arg;
	char buf[2*PRINTSIZE];

	if(up == nil || up->fgrp == nil)
		return 0;

	c = up->fgrp->fd[2];
	if(c==0 || (c->mode!=OWRITE && c->mode!=ORDWR))
		return 0;
	n = snprint(buf, sizeof buf, "%s %lud: ", up->text, up->pid);
	va_start(arg, fmt);
	n = vseprint(buf+n, buf+sizeof(buf), fmt, arg) - buf;
	va_end(arg);

	if(waserror())
		return 0;
	devtab[c->type]->write(c, buf, n, c->offset);
	poperror();

	lock(&c->ref.lk);
	c->offset += n;
	unlock(&c->ref.lk);

	return n;
}

static void
echoscreen(char *buf, int n)
{
	char *e, *p;
	char ebuf[128];
	int x;

	p = ebuf;
	e = ebuf + sizeof(ebuf) - 4;
	while(n-- > 0){
		if(p >= e){
			screenputs(ebuf, p - ebuf);
			p = ebuf;
		}
		x = *buf++;
		if(x == 0x15){
			*p++ = '^';
			*p++ = 'U';
			*p++ = '\n';
		} else
			*p++ = x;
	}
	if(p != ebuf)
		screenputs(ebuf, p - ebuf);
}

#if 0 // Plan 9 VX
static void
echoserialoq(char *buf, int n)
{
	char *e, *p;
	char ebuf[128];
	int x;

	p = ebuf;
	e = ebuf + sizeof(ebuf) - 4;
	while(n-- > 0){
		if(p >= e){
			qiwrite(serialoq, ebuf, p - ebuf);
			p = ebuf;
		}
		x = *buf++;
		if(x == '\n'){
			*p++ = '\r';
			*p++ = '\n';
		} else if(x == 0x15){
			*p++ = '^';
			*p++ = 'U';
			*p++ = '\n';
		} else
			*p++ = x;
	}
	if(p != ebuf)
		qiwrite(serialoq, ebuf, p - ebuf);
}
#endif

void
echo(char *buf, int n)
{
	static int ctrlt;
	int x;
	char *e, *p;

	if(n == 0)
		return;

	e = buf+n;
	for(p = buf; p < e; p++){
		switch(*p){
		case 0x10:	/* ^P */
			if(cpuserver && !kbd.ctlpoff){
				active.exiting = 1;
				return;
			}
			break;
		case 0x14:	/* ^T */
			ctrlt++;
			if(ctrlt > 2)
				ctrlt = 2;
			continue;
		}

		if(ctrlt != 2)
			continue;

		/* ^T escapes */
		ctrlt = 0;
		switch(*p){
		case 'S':
			x = splhi();
			dumpstack();
			procdump();
			splx(x);
			return;
		case 's':
			dumpstack();
			return;
		case 'x':
			xsummary();
			ixsummary();
			mallocsummary();
		//	memorysummary();
			pagersummary();
			return;
		case 'd':
			if(consdebug == nil)
				consdebug = rdb;
			else
				consdebug = nil;
			print("consdebug now 0x%p\n", consdebug);
			return;
		case 'D':
			if(consdebug == nil)
				consdebug = rdb;
			consdebug();
			return;
		case 'p':
			x = spllo();
			procdump();
			splx(x);
			return;
		case 'q':
			scheddump();
			return;
		case 'k':
			killbig("^t ^t k");
			return;
		case 'r':
			exit(0);
			return;
		}
	}

	qproduce(kbdq, buf, n);
	if(kbd.raw)
		return;
	kmesgputs(buf, n);
	if(screenputs != nil)
		echoscreen(buf, n);
	uartecho(buf, n);	// Plan 9 VX
}

/*
 *  Called by a uart interrupt for console input.
 *
 *  turn '\r' into '\n' before putting it into the queue.
 */
int
kbdcr2nl(Queue *q, int ch)
{
	char *next;

	ilock(&kbd.lockputc);		/* just a mutex */
	if(ch == '\r' && !kbd.raw)
		ch = '\n';
	next = kbd.iw+1;
	if(next >= kbd.ie)
		next = kbd.istage;
	if(next != kbd.ir){
		*kbd.iw = ch;
		kbd.iw = next;
	}
	iunlock(&kbd.lockputc);
	return 0;
}

/*
 *  Put character, possibly a rune, into read queue at interrupt time.
 *  Called at interrupt time to process a character.
 */
int
kbdputc(Queue *q, int ch)
{
	int n;
	Rune r;
	char buf[UTFmax];
	
	r = ch;
	n = runetochar(buf, &r);
	echo(buf, n);
	return 0;

#if 0 // Plan 9 VX
	int i, n;
	char buf[3];
	Rune r;
	char *next;

	if(kbd.ir == nil)
		return 0;		/* in case we're not inited yet */
	
	ilock(&kbd.lockputc);		/* just a mutex */
	r = ch;
	n = runetochar(buf, &r);
	for(i = 0; i < n; i++){
		next = kbd.iw+1;
		if(next >= kbd.ie)
			next = kbd.istage;
		if(next == kbd.ir)
			break;
		*kbd.iw = buf[i];
		kbd.iw = next;
	}
	iunlock(&kbd.lockputc);
	return 0;
#endif
}

/*
 *  we save up input characters till clock time to reduce
 *  per character interrupt overhead.
 */
#if 0 // Plan 9 VX
static void
kbdputcclock(void)
{
	char *iw;

	/* this amortizes cost of qproduce */
	if(kbd.iw != kbd.ir){
		iw = kbd.iw;
		if(iw < kbd.ir){
			echo(kbd.ir, kbd.ie-kbd.ir);
			kbd.ir = kbd.istage;
		}
		if(kbd.ir != iw){
			echo(kbd.ir, iw-kbd.ir);
			kbd.ir = iw;
		}
	}
}
#endif

enum{
	Qdir,
	Qbintime,
	Qcons,
	Qconsctl,
	Qcputime,
	Qdrivers,
	Qkmesg,
	Qkprint,
	Qhostdomain,
	Qhostowner,
	Qnull,
	Qosversion,
	Qpgrpid,
	Qpid,
	Qppid,
	Qrandom,
	Qreboot,
	Qswap,
	Qsysname,
	Qsysstat,
	Qtime,
	Quser,
	Qzero,
};

enum
{
	VLNUMSIZE=	22,
};

static Dirtab consdir[]={
	".",	{Qdir, 0, QTDIR},	0,		DMDIR|0555,
	"bintime",	{Qbintime},	24,		0664,
	"cons",		{Qcons},	0,		0660,
	"consctl",	{Qconsctl},	0,		0220,
	"cputime",	{Qcputime},	6*NUMSIZE,	0444,
	"drivers",	{Qdrivers},	0,		0444,
	"hostdomain",	{Qhostdomain},	DOMLEN,		0664,
	"hostowner",	{Qhostowner},	0,		0664,
	"kmesg",	{Qkmesg},	0,		0440,
	"kprint",	{Qkprint, 0, QTEXCL},	0,	DMEXCL|0440,
	"null",		{Qnull},	0,		0666,
	"osversion",	{Qosversion},	0,		0444,
	"pgrpid",	{Qpgrpid},	NUMSIZE,	0444,
	"pid",		{Qpid},		NUMSIZE,	0444,
	"ppid",		{Qppid},	NUMSIZE,	0444,
	"random",	{Qrandom},	0,		0444,
	"reboot",	{Qreboot},	0,		0664,
	"swap",		{Qswap},	0,		0664,
	"sysname",	{Qsysname},	0,		0664,
	"sysstat",	{Qsysstat},	0,		0666,
	"time",		{Qtime},	NUMSIZE+3*VLNUMSIZE,	0664,
	"user",		{Quser},	0,		0666,
	"zero",		{Qzero},	0,		0444,
};

int
readnum(ulong off, char *buf, ulong n, ulong val, int size)
{
	char tmp[64];

	snprint(tmp, sizeof(tmp), "%*lud", size-1, val);
	tmp[size-1] = ' ';
	if(off >= size)
		return 0;
	if(off+n > size)
		n = size-off;
	memmove(buf, tmp+off, n);
	return n;
}

int
readstr(ulong off, char *buf, ulong n, char *str)
{
	int size;

	size = strlen(str);
	if(off >= size)
		return 0;
	if(off+n > size)
		n = size-off;
	memmove(buf, str+off, n);
	return n;
}

static void
consinit(void)
{
	todinit();