C++ qlock函数代码示例

/*
 *  find the local address 'closest' to the remote system, copy it to
 *  local and return the ifc for that address
 */
void
findlocalip(Fs *f, uint8_t *local, uint8_t *remote)
{
	int version, atype = unspecifiedv6, atypel = unknownv6;
	int atyper, deprecated;
	uint8_t gate[IPaddrlen], gnet[IPaddrlen];
	Ipifc *ifc;
	Iplifc *lifc;
	Route *r;

	USED(atype);
	USED(atypel);
	qlock(f->ipifc);
	r = v6lookup(f, remote, nil);
 	version = (memcmp(remote, v4prefix, IPv4off) == 0)? V4: V6;

	if(r != nil){
		ifc = r->ifc;
		if(r->type & Rv4)
			v4tov6(gate, r->v4.gate);
		else {
			ipmove(gate, r->v6.gate);
			ipmove(local, v6Unspecified);
		}

		switch(version) {
		case V4:
			/* find ifc address closest to the gateway to use */
			for(lifc = ifc->lifc; lifc; lifc = lifc->next){
				maskip(gate, lifc->mask, gnet);
				if(ipcmp(gnet, lifc->net) == 0){
					ipmove(local, lifc->local);
					goto out;
				}
			}
			break;
		case V6:
			/* find ifc address with scope matching the destination */
			atyper = v6addrtype(remote);
			deprecated = 0;
			for(lifc = ifc->lifc; lifc; lifc = lifc->next){
				atypel = v6addrtype(lifc->local);
				/* prefer appropriate scope */
				if(atypel > atype && atype < atyper ||
				   atypel < atype && atype > atyper){
					ipmove(local, lifc->local);
					deprecated = !v6addrcurr(lifc);
					atype = atypel;
				} else if(atypel == atype){
					/* avoid deprecated addresses */
					if(deprecated && v6addrcurr(lifc)){
						ipmove(local, lifc->local);
						atype = atypel;
						deprecated = 0;
					}
				}
				if(atype == atyper && !deprecated)
					goto out;
			}
			if(atype >= atyper)
				goto out;
			break;
		default:
			panic("findlocalip: version %d", version);
		}
	}

	switch(version){
	case V4:
		findprimaryipv4(f, local);
		break;
	case V6:
		findprimaryipv6(f, local);
		break;
	default:
		panic("findlocalip2: version %d", version);
	}

out:
	qunlock(f->ipifc);
}

long
sysrfork(ulong *arg)
{
	Proc *p;
	int n, i;
	Fgrp *ofg;
	Pgrp *opg;
	Rgrp *org;
	Egrp *oeg;
	ulong pid, flag;
	Mach *wm;

	flag = arg[0];
	/* Check flags before we commit */
	if((flag & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG))
		error(Ebadarg);
	if((flag & (RFNAMEG|RFCNAMEG)) == (RFNAMEG|RFCNAMEG))
		error(Ebadarg);
	if((flag & (RFENVG|RFCENVG)) == (RFENVG|RFCENVG))
		error(Ebadarg);

	if((flag&RFPROC) == 0) {
		if(flag & (RFMEM|RFNOWAIT))
			error(Ebadarg);
		if(flag & (RFFDG|RFCFDG)) {
			ofg = up->fgrp;
			if(flag & RFFDG)
				up->fgrp = dupfgrp(ofg);
			else
				up->fgrp = dupfgrp(nil);
			closefgrp(ofg);
		}
		if(flag & (RFNAMEG|RFCNAMEG)) {
			opg = up->pgrp;
			up->pgrp = newpgrp();
			if(flag & RFNAMEG)
				pgrpcpy(up->pgrp, opg);
			/* inherit noattach */
			up->pgrp->noattach = opg->noattach;
			closepgrp(opg);
		}
		if(flag & RFNOMNT)
			up->pgrp->noattach = 1;
		if(flag & RFREND) {
			org = up->rgrp;
			up->rgrp = newrgrp();
			closergrp(org);
		}
		if(flag & (RFENVG|RFCENVG)) {
			oeg = up->egrp;
			up->egrp = smalloc(sizeof(Egrp));
			up->egrp->ref = 1;
			if(flag & RFENVG)
				envcpy(up->egrp, oeg);
			closeegrp(oeg);
		}
		if(flag & RFNOTEG)
			up->noteid = incref(&noteidalloc);
		return 0;
	}

	p = newproc();

	p->fpsave = up->fpsave;
	p->scallnr = up->scallnr;
	p->s = up->s;
	p->nerrlab = 0;
	p->slash = up->slash;
	p->dot = up->dot;
	incref(p->dot);

	memmove(p->note, up->note, sizeof(p->note));
	p->privatemem = up->privatemem;
	p->noswap = up->noswap;
	p->nnote = up->nnote;
	p->notified = 0;
	p->lastnote = up->lastnote;
	p->notify = up->notify;
	p->ureg = up->ureg;
	p->dbgreg = 0;

	/* Make a new set of memory segments */
	n = flag & RFMEM;
	qlock(&p->seglock);
	if(waserror()){
		qunlock(&p->seglock);
		nexterror();
	}
	for(i = 0; i < NSEG; i++)
		if(up->seg[i])
			p->seg[i] = dupseg(up->seg, i, n);
	qunlock(&p->seglock);
	poperror();

	/* File descriptors */
	if(flag & (RFFDG|RFCFDG)) {
		if(flag & RFFDG)
			p->fgrp = dupfgrp(up->fgrp);
		else
			p->fgrp = dupfgrp(nil);
//.........这里部分代码省略.........

Packet*
_vtrpc(VtConn *z, Packet *p, VtFcall *tx)
{
	int i;
	uchar tag, buf[2], *top;
	Rwait *r, *rr;

	if(z == nil){
		werrstr("not connected");
		packetfree(p);
		return nil;
	}

	/* must malloc because stack could be private */
	r = vtmallocz(sizeof(Rwait));

	qlock(&z->lk);
	r->r.l = &z->lk;
	tag = gettag(z, r);
	if(tx){
		/* vtfcallrpc can't print packet because it doesn't have tag */
		tx->tag = tag;
		if(chattyventi)
			fprint(2, "%s -> %F\n", argv0, tx);
	}

	/* slam tag into packet */
	top = packetpeek(p, buf, 0, 2);
	if(top == nil){
		packetfree(p);
		return nil;
	}
	if(top == buf){
		werrstr("first two bytes must be in same packet fragment");
		packetfree(p);
		vtfree(r);
		return nil;
	}
	top[1] = tag;
	qunlock(&z->lk);
	if(vtsend(z, p) < 0){
		vtfree(r);
		return nil;
	}

	qlock(&z->lk);
	/* wait for the muxer to give us our packet */
	r->sleeping = 1;
	z->nsleep++;
	while(z->muxer && !r->done)
		rsleep(&r->r);
	z->nsleep--;
	r->sleeping = 0;

	/* if not done, there's no muxer: start muxing */
	if(!r->done){
		if(z->muxer)
			abort();
		z->muxer = 1;
		while(!r->done){
			qunlock(&z->lk);
			if((p = vtrecv(z)) == nil){
				werrstr("unexpected eof on venti connection");
				z->muxer = 0;
				vtfree(r);
				return nil;
			}
			qlock(&z->lk);
			muxrpc(z, p);
		}
		z->muxer = 0;
		/* if there is anyone else sleeping, wake first unfinished to mux */
		if(z->nsleep)
		for(i=0; i<256; i++){
			rr = z->wait[i];
			if(rr && rr->sleeping && !rr->done){
				rwakeup(&rr->r);
				break;
			}
		}
	}

	p = r->p;
	puttag(z, r, tag);
	vtfree(r);
	qunlock(&z->lk);
	return p;
}

static
Xfid*
fsysread(Xfid *x, Fid *f)
{
	Fcall t;
	uchar *b;
	int i, id, n, o, e, j, k, *ids, nids;
	Dirtab *d, dt;
	Column *c;
	uint clock, len;
	char buf[16];

	if(f->qid.type & QTDIR){
		if(FILE(f->qid) == Qacme){	/* empty dir */
			t.data = nil;
			t.count = 0;
			respond(x, &t, nil);
			return x;
		}
		o = x->offset;
		e = x->offset+x->count;
		clock = getclock();
		b = emalloc(messagesize);
		id = WIN(f->qid);
		n = 0;
		if(id > 0)
			d = dirtabw;
		else
			d = dirtab;
		d++;	/* first entry is '.' */
		for(i=0; d->name!=nil && i<e; i+=len){
			len = dostat(WIN(x->f->qid), d, b+n, x->count-n, clock);
			if(len <= BIT16SZ)
				break;
			if(i >= o)
				n += len;
			d++;
		}
		if(id == 0){
			qlock(&row);
			nids = 0;
			ids = nil;
			for(j=0; j<row.ncol; j++){
				c = row.col[j];
				for(k=0; k<c->nw; k++){
					ids = erealloc(ids, (nids+1)*sizeof(int));
					ids[nids++] = c->w[k]->id;
				}
			}
			qunlock(&row);
			qsort(ids, nids, sizeof ids[0], idcmp);
			j = 0;
			dt.name = buf;
			for(; j<nids && i<e; i+=len){
				k = ids[j];
				sprint(dt.name, "%d", k);
				dt.qid = QID(k, Qdir);
				dt.type = QTDIR;
				dt.perm = DMDIR|0700;
				len = dostat(k, &dt, b+n, x->count-n, clock);
				if(len == 0)
					break;
				if(i >= o)
					n += len;
				j++;
			}
			free(ids);
		}
		t.data = (char*)b;
		t.count = n;
		respond(x, &t, nil);
		free(b);
		return x;
	}
	sendp(x->c, xfidread);
	return nil;
}

long
consread(Chan *c, void *va, long count, vlong offset)
{
	int i, n, ch, eol;
	Pointer m;
	char *p, buf[64];

	if(c->qid.type & QTDIR)
		return devdirread(c, va, count, contab, nelem(contab), devgen);

	switch((ulong)c->qid.path) {
	default:
		error(Egreg);
	case Qsysctl:
		return readstr(offset, va, count, VERSION);
	case Qsysname:
		if(ossysname == nil)
			return 0;
		return readstr(offset, va, count, ossysname);
	case Qrandom:
		return randomread(va, count);
	case Qnotquiterandom:
		pseudoRandomBytes(va, count);
		return count;
	case Qpin:
		p = "pin set";
		if(up->env->pgrp->pin == Nopin)
			p = "no pin";
		return readstr(offset, va, count, p);
	case Qhostowner:
		return readstr(offset, va, count, eve);
	case Qhoststdin:
		return read(0, va, count);	/* should be pread */
	case Quser:
		return readstr(offset, va, count, up->env->user);
	case Qjit:
		snprint(buf, sizeof(buf), "%d", cflag);
		return readstr(offset, va, count, buf);
	case Qtime:
		snprint(buf, sizeof(buf), "%.lld", timeoffset + osusectime());
		return readstr(offset, va, count, buf);
	case Qdrivers:
		p = malloc(READSTR);
		if(p == nil)
			error(Enomem);
		n = 0;
		for(i = 0; devtab[i] != nil; i++)
			n += snprint(p+n, READSTR-n, "#%C %s\n", devtab[i]->dc,  devtab[i]->name);
		n = readstr(offset, va, count, p);
		free(p);
		return n;
	case Qmemory:
		return poolread(va, count, offset);

	case Qnull:
		return 0;
	case Qmsec:
		return readnum(offset, va, count, osmillisec(), NUMSIZE);
	case Qcons:
		qlock(&kbd.q);
		if(waserror()){
			qunlock(&kbd.q);
			nexterror();
		}

		if(dflag)
			error(Enonexist);

		while(!qcanread(lineq)) {
			qread(kbdq, &kbd.line[kbd.x], 1);
			ch = kbd.line[kbd.x];
			if(kbd.raw){
				qiwrite(lineq, &kbd.line[kbd.x], 1);
				continue;
			}
			eol = 0;
			switch(ch) {
			case '\b':
				if(kbd.x)
					kbd.x--;
				break;
			case 0x15:
				kbd.x = 0;
				break;
			case '\n':
			case 0x04:
				eol = 1;
			default:
				kbd.line[kbd.x++] = ch;
				break;
			}
			if(kbd.x == sizeof(kbd.line) || eol){
				if(ch == 0x04)
					kbd.x--;
				qwrite(lineq, kbd.line, kbd.x);
				kbd.x = 0;
			}
		}
		n = qread(lineq, va, count);
		qunlock(&kbd.q);
//.........这里部分代码省略.........

static void
tcpreader(void *a)
{
	Session *s = a;
	uchar *buf;
	int buflen = 0x1ffff + 4;
	buf = nbemalloc(buflen);
	for (;;) {
		int n;
		uchar flags;
		ushort length;

		n = readn(s->fd, buf, 4);
		if (n != 4) {
		die:
			free(buf);
			if (s->state == Connected)
				(*s->write)(s, nil, -1);
			deletesession(s);
			return;
		}
		flags = buf[1];
		length = nhgets(buf + 2) | ((flags & 1) << 16);
		n = readn(s->fd, buf + 4, length);
		if (n != length)
			goto die;
		if (flags & 0xfe) {
			print("nbss: invalid flags field 0x%.2ux\n", flags);
			goto die;
		}
		switch (buf[0]) {
		case 0: /* session message */
			if (s->state != Connected && s->state != Dead) {
				print("nbss: unexpected session message\n");
				goto die;
			}
			if (s->state == Connected) {
				if ((*s->write)(s, buf + 4, length) != 0) {
					s->state = Dead;
					goto die;
				}
			}
			break;
		case 0x81: /* session request */ {
			uchar *p, *ep;
			Listen *l;
			int k;
			int called_found;
			uchar error_code;

			if (s->state == Connected) {
				print("nbss: unexpected session request\n");
				goto die;
			}
			p = buf + 4;
			ep = p + length;
			k = nbnamedecode(p, p, ep, s->to);
			if (k == 0) {
				print("nbss: malformed called name in session request\n");
				goto die;
			}
			p += k;
			k = nbnamedecode(p, p, ep, s->from);
			if (k == 0) {
				print("nbss: malformed calling name in session request\n");
				goto die;
			}
/*
			p += k;
			if (p != ep) {
				print("nbss: extra data at end of session request\n");
				goto die;
			}
*/
			called_found = 0;
//print("nbss: called %B calling %B\n", s->to, s->from);
			qlock(&listens);
			for (l = listens.head; l; l = l->next)
				if (nbnameequal(l->to, s->to)) {
					called_found = 1;
					if (nbnameequal(l->from, s->from))
						break;
				}
			if (l == nil) {
				qunlock(&listens);
				error_code  = called_found ? 0x81 : 0x80;
			replydie:
				buf[0] = 0x83;
				buf[1] = 0;
				hnputs(buf + 2, 1);
				buf[4] = error_code;
				write(s->fd, buf, 5);
				goto die;
			}
			if (!(*l->accept)(l->magic, s, &s->write)) {
				qunlock(&listens);
				error_code = 0x83;
				goto replydie;
			}
			buf[0] = 0x82;
//.........这里部分代码省略.........

void
waitthread(void *v)
{
    Waitmsg *w;
    Command *c, *lc;
    uint pid;
    int found, ncmd;
    Rune *cmd;
    char *err;
    Text *t;
    Pid *pids, *p, *lastp;
    enum { WErr, WKill, WWait, WCmd, NWALT };
    Alt alts[NWALT+1];

    USED(v);
    threadsetname("waitthread");
    pids = nil;
    alts[WErr].c = cerr;
    alts[WErr].v = &err;
    alts[WErr].op = CHANRCV;
    alts[WKill].c = ckill;
    alts[WKill].v = &cmd;
    alts[WKill].op = CHANRCV;
    alts[WWait].c = cwait;
    alts[WWait].v = &w;
    alts[WWait].op = CHANRCV;
    alts[WCmd].c = ccommand;
    alts[WCmd].v = &c;
    alts[WCmd].op = CHANRCV;
    alts[NWALT].op = CHANEND;

    command = nil;
    for(;;) {
        switch(alt(alts)) {
        case WErr:
            qlock(&row.lk);
            warning(nil, "%s", err);
            free(err);
            flushimage(display, 1);
            qunlock(&row.lk);
            break;
        case WKill:
            found = FALSE;
            ncmd = runestrlen(cmd);
            for(c=command; c; c=c->next) {
                /* -1 for blank */
                if(runeeq(c->name, c->nname-1, cmd, ncmd) == TRUE) {
                    if(postnote(PNGROUP, c->pid, "kill") < 0)
                        warning(nil, "kill %S: %r\n", cmd);
                    found = TRUE;
                }
            }
            if(!found)
                warning(nil, "Kill: no process %S\n", cmd);
            free(cmd);
            break;
        case WWait:
            pid = w->pid;
            lc = nil;
            for(c=command; c; c=c->next) {
                if(c->pid == pid) {
                    if(lc)
                        lc->next = c->next;
                    else
                        command = c->next;
                    break;
                }
                lc = c;
            }
            qlock(&row.lk);
            t = &row.tag;
            textcommit(t, TRUE);
            if(c == nil) {
                /* helper processes use this exit status */
                if(strncmp(w->msg, "libthread", 9) != 0) {
                    p = emalloc(sizeof(Pid));
                    p->pid = pid;
                    strncpy(p->msg, w->msg, sizeof(p->msg));
                    p->next = pids;
                    pids = p;
                }
            } else {
                if(search(t, c->name, c->nname)) {
                    textdelete(t, t->q0, t->q1, TRUE);
                    textsetselect(t, 0, 0);
                }
                if(w->msg[0])
                    warning(c->md, "%.*S: exit %s\n", c->nname-1, c->name, w->msg);
                flushimage(display, 1);
            }
            qunlock(&row.lk);
            free(w);
Freecmd:
            if(c) {
                if(c->iseditcmd)
                    sendul(cedit, 0);
                free(c->text);
                free(c->name);
                fsysdelid(c->md);
                free(c);
//.........这里部分代码省略.........

static int
xgraph(HConnect *c)
{
	char *name;
	Hio *hout;
	Memimage *m;
	int dotext;
	Graph g;
	Arg arg;
	char *graph, *a;

	name = hargstr(c, "arg", "");
	if((arg.index = findname(name)) == -1 && strcmp(name, "*") != 0){
		werrstr("unknown name %s", name);
		goto error;
	}
	a = hargstr(c, "arg2", "");
	if(a[0] && (arg.index2 = findname(a)) == -1){
		werrstr("unknown name %s", a);
		goto error;
	}

	g.arg = &arg;
	g.t0 = hargint(c, "t0", -120);
	g.t1 = hargint(c, "t1", 0);
	g.min = hargint(c, "min", -1);
	g.max = hargint(c, "max", -1);
	g.wid = hargint(c, "wid", -1);
	g.ht = hargint(c, "ht", -1);
	dotext = hargstr(c, "text", "")[0] != 0;
	g.fill = hargint(c, "fill", -1);
	
	graph = hargstr(c, "graph", "raw");
	if(strcmp(graph, "raw") == 0)
		g.fn = rawgraph;
	else if(strcmp(graph, "diskbw") == 0)
		g.fn = diskgraph;
	else if(strcmp(graph, "iobw") == 0)
		g.fn = iograph;
	else if(strcmp(graph, "netbw") == 0)
		g.fn = netgraph;
	else if(strcmp(graph, "diff") == 0)
		g.fn = diffgraph;
	else if(strcmp(graph, "pct") == 0)
		g.fn = pctgraph;
	else if(strcmp(graph, "pctdiff") == 0)
		g.fn = pctdiffgraph;
	else if(strcmp(graph, "divdiff") == 0)
		g.fn = divdiffgraph;
	else{
		werrstr("unknown graph %s", graph);
		goto error;
	}

	if(dotext){
		hsettype(c, "text/plain");
		dotextbin(&c->hout, &g);
		hflush(&c->hout);
		return 0;
	}

	m = statgraph(&g);
	if(m == nil)
		goto error;

	if(hsettype(c, "image/png") < 0)
		return -1;
	hout = &c->hout;
	writepng(hout, m);
	qlock(&memdrawlock);
	freememimage(m);
	qunlock(&memdrawlock);
	hflush(hout);
	return 0;

error:
	return herror(c);
}

static int
chanio(Ep *ep, Hostchan *hc, int dir, int pid, void *a, int len)
{
	Ctlr *ctlr;
	int nleft, n, nt, i, maxpkt, npkt;
	uint hcdma, hctsiz;

	ctlr = ep->hp->aux;
	maxpkt = ep->maxpkt;
	npkt = HOWMANY(len, ep->maxpkt);
	if(npkt == 0)
		npkt = 1;

	hc->hcchar = (hc->hcchar & ~Epdir) | dir;
	if(dir == Epin)
		n = ROUND(len, ep->maxpkt);
	else
		n = len;
	hc->hctsiz = n | npkt<<OPktcnt | pid;
	hc->hcdma  = dmaaddr(a);

	nleft = len;
	logstart(ep);
	for(;;){
		hcdma = hc->hcdma;
		hctsiz = hc->hctsiz;
		hc->hctsiz = hctsiz & ~Dopng;
		if(hc->hcchar&Chen){
			dprint("ep%d.%d before chanio hcchar=%8.8ux\n",
				ep->dev->nb, ep->nb, hc->hcchar);
			hc->hcchar |= Chen | Chdis;
			while(hc->hcchar&Chen)
				;
			hc->hcint = Chhltd;
		}
		if((i = hc->hcint) != 0){
			dprint("ep%d.%d before chanio hcint=%8.8ux\n",
				ep->dev->nb, ep->nb, i);
			hc->hcint = i;
		}
		if(hc->hcsplt & Spltena){
			qlock(&ctlr->split);
			sofwait(ctlr, hc - ctlr->regs->hchan);
			if((dwc.regs->hfnum & 1) == 0)
				hc->hcchar &= ~Oddfrm;
			else
				hc->hcchar |= Oddfrm;
		}
		hc->hcchar = (hc->hcchar &~ Chdis) | Chen;
		clog(ep, hc);
		if(ep->ttype == Tbulk && dir == Epin)
			i = chanwait(ep, ctlr, hc, /* Ack| */ Chhltd);
		else if(ep->ttype == Tintr && (hc->hcsplt & Spltena))
			i = chanwait(ep, ctlr, hc, Chhltd);
		else
			i = chanwait(ep, ctlr, hc, Chhltd|Nak);
		clog(ep, hc);
		hc->hcint = i;

		if(hc->hcsplt & Spltena){
			hc->hcsplt &= ~Compsplt;
			qunlock(&ctlr->split);
		}

		if((i & Xfercomp) == 0 && i != (Chhltd|Ack) && i != Chhltd){
			if(i & Stall)
				error(Estalled);
			if(i & (Nyet|Frmovrun))
				continue;
			if(i & Nak){
				if(ep->ttype == Tintr)
					tsleep(&up->sleep, return0, 0, ep->pollival);
				else
					tsleep(&up->sleep, return0, 0, 1);
				continue;
			}
			logdump(ep);
			print("usbotg: ep%d.%d error intr %8.8ux\n",
				ep->dev->nb, ep->nb, i);
			if(i & ~(Chhltd|Ack))
				error(Eio);
			if(hc->hcdma != hcdma)
				print("usbotg: weird hcdma %x->%x intr %x->%x\n",
					hcdma, hc->hcdma, i, hc->hcint);
		}
		n = hc->hcdma - hcdma;
		if(n == 0){
			if((hc->hctsiz & Pktcnt) != (hctsiz & Pktcnt))
				break;
			else
				continue;
		}
		if(dir == Epin && ep->ttype == Tbulk && n == nleft){
			nt = (hctsiz & Xfersize) - (hc->hctsiz & Xfersize);
			if(nt != n){
				if(n == ROUND(nt, 4))
					n = nt;
				else
					print("usbotg: intr %8.8ux "
						"dma %8.8ux-%8.8ux "
//.........这里部分代码省略.........

static int
sdgen(Chan* c, char*, Dirtab*, int, int s, Dir* dp)
{
	Qid q;
	uvlong l;
	int i, r;
	SDpart *pp;
	SDunit *unit;
	SDev *sdev;

	switch(TYPE(c->qid)){
	case Qtopdir:
		if(s == DEVDOTDOT){
			mkqid(&q, QID(0, 0, 0, Qtopdir), 0, QTDIR);
			snprint(up->genbuf, sizeof up->genbuf, "#%C",
				sddevtab.dc);
			devdir(c, q, up->genbuf, 0, eve, 0555, dp);
			return 1;
		}

		if(s+Qtopbase < Qunitdir)
			return sd1gen(c, s+Qtopbase, dp);
		s -= (Qunitdir-Qtopbase);

		qlock(&devslock);
		for(i=0; i<nelem(devs); i++){
			if(devs[i]){
				if(s < devs[i]->nunit)
					break;
				s -= devs[i]->nunit;
			}
		}

		if(i == nelem(devs)){
			/* Run off the end of the list */
			qunlock(&devslock);
			return -1;
		}

		if((sdev = devs[i]) == nil){
			qunlock(&devslock);
			return 0;
		}

		incref(&sdev->r);
		qunlock(&devslock);

		if((unit = sdev->unit[s]) == nil)
			if((unit = sdgetunit(sdev, s)) == nil){
				decref(&sdev->r);
				return 0;
			}

		mkqid(&q, QID(sdev->idno, s, 0, Qunitdir), 0, QTDIR);
		if(emptystr(unit->user))
			kstrdup(&unit->user, eve);
		devdir(c, q, unit->name, 0, unit->user, unit->perm, dp);
		decref(&sdev->r);
		return 1;

	case Qunitdir:
		if(s == DEVDOTDOT){
			mkqid(&q, QID(0, 0, 0, Qtopdir), 0, QTDIR);
			snprint(up->genbuf, sizeof up->genbuf, "#%C",
				sddevtab.dc);
			devdir(c, q, up->genbuf, 0, eve, 0555, dp);
			return 1;
		}

		if((sdev = sdgetdev(DEV(c->qid))) == nil){
			devdir(c, c->qid, "unavailable", 0, eve, 0, dp);
			return 1;
		}

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

		/*
		 * Check for media change.
		 * If one has already been detected, sectors will be zero.
		 * If there is one waiting to be detected, online
		 * will return > 1.
		 * Online is a bit of a large hammer but does the job.
		 */
		if(unit->sectors == 0
		|| (unit->dev->ifc->online && unit->dev->ifc->online(unit) > 1))
			sdinitpart(unit);

		i = s+Qunitbase;
		if(i < Qpart){
			r = sd2gen(c, i, dp);
			qunlock(&unit->ctl);
			decref(&sdev->r);
			return r;
		}
		i -= Qpart;
		if(unit->part == nil || i >= unit->npart){
			qunlock(&unit->ctl);
			decref(&sdev->r);
			break;
//.........这里部分代码省略.........

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->env->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] & SDinq1removable)){
		qunlock(&unit->ctl);
		poperror();
	}

	b = sdmalloc(nb*unit->secsize);
	if(b == nil)
		error(Enomem);
	if(waserror()){
		sdfree(b);
		if(!(unit->inquiry[1] & SDinq1removable))
			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)
//.........这里部分代码省略.........

static long
sdwrite(Chan* c, void* a, long n, vlong off)
{
	char *f0;
	int i;
	uvlong end, start;
	Cmdbuf *cb;
	SDifc *ifc;
	SDreq *req;
	SDunit *unit;
	SDev *sdev;

	switch(TYPE(c->qid)){
	default:
		error(Eperm);
	case Qtopctl:
		cb = parsecmd(a, n);
		if(waserror()){
			free(cb);
			nexterror();
		}
		if(cb->nf == 0)
			error("empty control message");
		f0 = cb->f[0];
		cb->f++;
		cb->nf--;
		if(strcmp(f0, "config") == 0){
			/* wormhole into ugly legacy interface */
			legacytopctl(cb);
			poperror();
			free(cb);
			break;
		}
		/*
		 * "ata arg..." invokes sdifc[i]->wtopctl(nil, cb),
		 * where sdifc[i]->name=="ata" and cb contains the args.
		 */
		ifc = nil;
		sdev = nil;
		for(i=0; sdifc[i]; i++){
			if(strcmp(sdifc[i]->name, f0) == 0){
				ifc = sdifc[i];
				sdev = nil;
				goto subtopctl;
			}
		}
		/*
		 * "sd1 arg..." invokes sdifc[i]->wtopctl(sdev, cb),
		 * where sdifc[i] and sdev match controller letter "1",
		 * and cb contains the args.
		 */
		if(f0[0]=='s' && f0[1]=='d' && f0[2] && f0[3] == 0){
			if((sdev = sdgetdev(f0[2])) != nil){
				ifc = sdev->ifc;
				goto subtopctl;
			}
		}
		error("unknown interface");

	subtopctl:
		if(waserror()){
			if(sdev)
				decref(&sdev->r);
			nexterror();
		}
		if(ifc->wtopctl)
			ifc->wtopctl(sdev, cb);
		else
			error(Ebadctl);
		poperror();
		poperror();
		if (sdev)
			decref(&sdev->r);
		free(cb);
		break;

	case Qctl:
		cb = parsecmd(a, n);
		sdev = sdgetdev(DEV(c->qid));
		if(sdev == nil)
			error(Enonexist);
		unit = sdev->unit[UNIT(c->qid)];

		qlock(&unit->ctl);
		if(waserror()){
			qunlock(&unit->ctl);
			decref(&sdev->r);
			free(cb);
			nexterror();
		}
		if(unit->vers != c->qid.vers)
			error(Echange);

		if(cb->nf < 1)
			error(Ebadctl);
		if(strcmp(cb->f[0], "part") == 0){
			if(cb->nf != 4)
				error(Ebadctl);
			if(unit->sectors == 0 && !sdinitpart(unit))
				error(Eio);
//.........这里部分代码省略.........

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);
		if(p == nil)
			error(Enomem);
		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);
		return n;

	case Qtopdir:
	case Qunitdir:
		return devdirread(c, a, n, 0, 0, sdgen);

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

		unit = sdev->unit[UNIT(c->qid)];
		m = 16*1024;	/* room for register dumps */
		p = malloc(m);
		if(p == nil)
			error(Enomem);
		l = snprint(p, m, "inquiry %.48s\n",
			(char*)unit->inquiry+8);
		qlock(&unit->ctl);
		/*
		 * If there's a device specific routine it must
		 * provide all information pertaining to night geometry
		 * and the garscadden trains.
		 */
		if(unit->dev->ifc->rctl)
			l += unit->dev->ifc->rctl(unit, p+l, m-l);
		if(unit->sectors == 0)
			sdinitpart(unit);
		if(unit->sectors){
			if(unit->dev->ifc->rctl == nil)
				l += snprint(p+l, m-l,
					"geometry %llud %lud\n",
					unit->sectors, unit->secsize);
			pp = unit->part;
			for(i = 0; i < unit->npart; i++){
				if(pp->valid)
					l += snprint(p+l, m-l,
						"part %s %llud %llud\n",
						pp->name, pp->start, pp->end);
				pp++;
			}
		}
		qunlock(&unit->ctl);
		decref(&sdev->r);
		l = readstr(offset, a, n, p);
		free(p);
		return l;

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

		unit = sdev->unit[UNIT(c->qid)];
		qlock(&unit->raw);
		if(waserror()){
			qunlock(&unit->raw);
			decref(&sdev->r);
			nexterror();
		}
		if(unit->state == Rawdata){
			unit->state = Rawstatus;
			i = sdrio(unit->req, a, n);
		}
		else if(unit->state == Rawstatus){
			status = unit->req->status;
			unit->state = Rawcmd;
			free(unit->req);
			unit->req = nil;
			i = readnum(0, a, n, status, NUMSIZE);
		} else
//.........这里部分代码省略.........

/*
 *  Decrement reference for this address on this link.
 *  Unlink from selftab if this is the last ref.
 *	called with c->car locked
 */
static void
remselfcache(Fs *f, Ipifc *ifc, Iplifc *lifc, uint8_t *a)
{
	Ipself *p, **l;
	Iplink *link, **l_self, **l_lifc;

	qlock(f->self);

	/* find the unique selftab entry */
	l = &f->self->hash[hashipa(a)];
	for(p = *l; p; p = *l){
		if(ipcmp(p->a, a) == 0)
			break;
		l = &p->next;
	}

	if(p == nil)
		goto out;

	/*
	 *  walk down links from an ifc looking for one
	 *  that matches the selftab entry
	 */
	l_lifc = &lifc->link;
	for(link = *l_lifc; link; link = *l_lifc){
		if(link->self == p)
			break;
		l_lifc = &link->lifclink;
	}

	if(link == nil)
		goto out;

	/*
	 *  walk down the links from the selftab looking for
	 *  the one we just found
	 */
	l_self = &p->link;
	for(link = *l_self; link; link = *l_self){
		if(link == *l_lifc)
			break;
		l_self = &link->selflink;
	}

	if(link == nil)
		panic("remselfcache");

	if(--(link->ref) != 0)
		goto out;

	if((p->type & Rmulti) && ifc->medium->remmulti != nil)
		(*ifc->medium->remmulti)(ifc, a, lifc->local);

	/* ref == 0, remove from both chains and free the link */
	*l_lifc = link->lifclink;
	*l_self = link->selflink;
	iplinkfree(link);

	if(p->link != nil)
		goto out;

	/* remove from routing table */
	if(isv4(a))
		v4delroute(f, a+IPv4off, IPallbits+IPv4off, 1);
	else
		v6delroute(f, a, IPallbits, 1);

	/* no more links, remove from hash and free */
	*l = p->next;
	ipselffree(p);

	/* if IPnoaddr, forget */
	if(ipcmp(a, v4prefix) == 0 || ipcmp(a, IPnoaddr) == 0)
		f->self->acceptall = 0;

out:
	qunlock(f->self);
}

void
cwrite(Chan* c, uchar *buf, int len, vlong off)
{
	int o, eo;
	Mntcache *m;
	ulong eblock, ee;
	Extent *p, *f, *e, *tail;
	ulong offset;

	if(off > maxcache || len == 0)
		return;

	m = c->mcp;
	if(m == 0)
		return;

	qlock(m);
	if(cdev(m, c) == 0) {
		qunlock(m);
		c->mcp = 0;
		return;
	}

	offset = off;
	m->qid.vers++;
	c->qid.vers++;

	p = 0;
	for(f = m->list; f; f = f->next) {
		if(f->start >= offset)
			break;
		p = f;
	}

	if(p != 0) {
		ee = p->start+p->len;
		eo = offset - p->start;
		/* pack in predecessor if there is space */
		if(offset <= ee && eo < BY2PG) {
			o = len;
			if(o > BY2PG - eo)
				o = BY2PG - eo;
			if(cpgmove(p, buf, eo, o)) {
				if(eo+o > p->len)
					p->len = eo+o;
				buf += o;
				len -= o;
				offset += o;
			}
		}
	}

	/* free the overlap -- it's a rare case */
	eblock = offset+len;
	while(f && f->start < eblock) {
		e = f->next;
		extentfree(f);
		f = e;
	}

	/* link the block (if any) into the middle */
	e = cchain(buf, offset, len, &tail);
	if(e != 0) {
		tail->next = f;
		f = e;
	}

	if(p == 0)
		m->list = f;
	else
		p->next = f;
	qunlock(m);
}