9p1.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

#include	"all.h"

#include	"9p1.h"

extern Nvrsafe	nvr;

typedef struct {
	uchar	chal[CHALLEN];		/* locally generated challenge */
	uchar	rchal[CHALLEN];		/* remotely generated challenge */
	Lock	idlock;
	ulong	idoffset;		/* offset of id vector */
	ulong	idvec;			/* vector of acceptable id's */
} Authinfo;

static void
f_nop(Chan *cp, Fcall*, Fcall*)
{

	if(CHAT(cp))
		print("c_nop %d\n", cp->chan);
}

static void
f_flush(Chan *cp, Fcall*, Fcall*)
{

	if(CHAT(cp))
		print("c_flush %d\n", cp->chan);
	runlock(&cp->reflock);
	wlock(&cp->reflock);
	wunlock(&cp->reflock);
	rlock(&cp->reflock);
}

/*
 *  create a challenge for a fid space
 */
static void
mkchallenge(Authinfo *aip)
{
	int i;

	srand((ulong)aip + m->ticks);
	for(i = 0; i < CHALLEN; i++)
		aip->chal[i] = nrand(256);

	aip->idoffset = 0;
	aip->idvec = 0;
}

static void
f_session(Chan *cp, Fcall *in, Fcall *ou)
{
	Authinfo *aip;

	aip = (Authinfo*)cp->authinfo;

	if(CHAT(cp))
		print("c_session %d\n", cp->chan);
	memmove(aip->rchal, in->chal, sizeof(aip->rchal));
	mkchallenge(aip);
	memmove(ou->chal, aip->chal, sizeof(ou->chal));
	if(noauth || wstatallow)
		memset(ou->authid, 0, sizeof(ou->authid));
	else
		memmove(ou->authid, nvr.authid, sizeof(ou->authid));

	sprint(ou->authdom, "%s.%s", service, nvr.authdom);
	fileinit(cp);
}

/*
 *  match a challenge from an attach
 */
static int
authorize(Chan *cp, Fcall *in, Fcall *ou)
{
	Ticket t;
	Authenticator a;
	int x;
	ulong bit;
	Authinfo *aip;

	if(noauth || wstatallow)	/* set to allow entry during boot */
		return 1;

	if(strcmp(in->uname, "none") == 0)
		return 1;

	if(in->type == Toattach)
		return 0;

	/* decrypt and unpack ticket */
	convM2T9p1(in->ticket, &t, nvr.authkey);
	if(t.num != AuthTs){
		print("9p1: bad AuthTs num\n");
		return 0;
	}

	/* decrypt and unpack authenticator */
	convM2A9p1(in->auth, &a, t.key);
	if(a.num != AuthAc){
		print("9p1: bad AuthAc num\n");
		return 0;
	}

	/* challenges must match */
	aip = (Authinfo*)cp->authinfo;
	if(memcmp(a.chal, aip->chal, sizeof(a.chal)) != 0){
		print("9p1: bad challenge\n");
		return 0;
	}

	/*
	 *  the id must be in a valid range.  the range is specified by a
	 *  lower bound (idoffset) and a bit vector (idvec) where a
	 *  bit set to 1 means unusable
	 */
	lock(&aip->idlock);
	x = a.id - aip->idoffset;
	bit = 1<<x;
	if(x < 0 || x > 31 || (bit&aip->idvec)){
		unlock(&aip->idlock);
		print("9p1: id out of range: idoff %ld idvec %lux id %ld\n",
 		   aip->idoffset, aip->idvec, a.id);
		return 0;
	}
	aip->idvec |= bit;

	/* normalize the vector */
	while(aip->idvec&0xffff0001){
		aip->idvec >>= 1;
		aip->idoffset++;
	}
	unlock(&aip->idlock);

	/* ticket name and attach name must match */
	if(memcmp(in->uname, t.cuid, sizeof(in->uname)) != 0){
		print("9p1: names don't match\n");
		return 0;
	}

	/* copy translated name into input record */
	memmove(in->uname, t.suid, sizeof(in->uname));

	/* craft a reply */
	a.num = AuthAs;
	memmove(a.chal, aip->rchal, CHALLEN);
	convA2M9p1(&a, ou->rauth, t.key);

	return 1;
}

/*
 * buggery to give false qid for
 * the top 2 levels of the dump fs
 */
void
mkqid(Qid* qid, Dentry *d, int buggery)
{
	int c;

	if(buggery && d->qid.path == (QPDIR|QPROOT)){
		c = d->name[0];
		if(c >= '0' && c <= '9'){
			qid->path = 3;
			qid->vers = d->qid.version;
			qid->type = QTDIR;

			c = (c-'0')*10 + (d->name[1]-'0');
			if(c >= 1 && c <= 12)
				qid->path = 4;
			return;
		}
	}

	mkqid9p2(qid, &d->qid, d->mode);
}

int
mkqidcmp(Qid* qid, Dentry *d)
{
	Qid tmp;

	mkqid(&tmp, d, 1);
	if(qid->path == tmp.path && qid->type == tmp.type)
		return 0;
	return Eqid;
}

static void
f_attach(Chan *cp, Fcall *in, Fcall *ou)
{
	Iobuf *p;
	Dentry *d;
	File *f;
	int u;
	Filsys *fs;
	Off raddr;

	if(CHAT(cp)) {
		print("c_attach %d\n", cp->chan);
		print("	fid = %d\n", in->fid);
		print("	uid = %s\n", in->uname);
		print("	arg = %s\n", in->aname);
	}

	ou->qid = QID9P1(0,0);
	ou->fid = in->fid;
	if(!in->aname[0])	/* default */
		strncpy(in->aname, "main", sizeof(in->aname));
	p = 0;
	f = filep(cp, in->fid, 1);
	if(!f) {
		ou->err = Efid;
		goto out;
	}

	u = -1;
	if(cp != cons.chan) {
		if(noattach && strcmp(in->uname, "none")) {
			ou->err = Enoattach;
			goto out;
		}
		if(authorize(cp, in, ou) == 0 || strcmp(in->uname, "adm") == 0) {
			ou->err = Eauth;
			goto out;
		}
		u = strtouid(in->uname);
		if(u < 0) {
			ou->err = Ebadu;
			goto out;
		}
	}
	f->uid = u;

	fs = fsstr(in->aname);
	if(fs == 0) {
		ou->err = Ebadspc;
		goto out;
	}
	raddr = getraddr(fs->dev);
	p = getbuf(fs->dev, raddr, Bread);
	d = getdir(p, 0);
	if(!d || checktag(p, Tdir, QPROOT) || !(d->mode & DALLOC)) {
		ou->err = Ealloc;
		goto out;
	}
	if (iaccess(f, d, DEXEC) ||
	    f->uid == 0 && fs->dev->type == Devro) {
		/*
		 * 'none' not allowed on dump
		 */
		ou->err = Eaccess;
		goto out;
	}
	accessdir(p, d, FREAD, f->uid);
	mkqid(&f->qid, d, 1);
	f->fs = fs;
	f->addr = raddr;
	f->slot = 0;
	f->open = 0;
	freewp(f->wpath);
	f->wpath = 0;

	mkqid9p1(&ou->qid, &f->qid);

	strncpy(cp->whoname, in->uname, sizeof(cp->whoname));
	cp->whotime = time();
	if(cons.flags & attachflag)
		print("9p1: attach %s %T to \"%s\" C%d\n",
			cp->whoname, cp->whotime, fs->name, cp->chan);

out:
	if((cons.flags & attachflag) && ou->err)
		print("9p1: attach %s %T SUCK EGGS --- %s\n",
			in->uname, time(), errstr9p[ou->err]);
	if(p)
		putbuf(p);
	if(f) {
		qunlock(f);
		if(ou->err)
			freefp(f);
	}
}

static void
f_clone(Chan *cp, Fcall *in, Fcall *ou)
{
	File *f1, *f2;
	Wpath *p;
	int fid, fid1;

	if(CHAT(cp)) {
		print("c_clone %d\n", cp->chan);
		print("	old fid = %d\n", in->fid);
		print("	new fid = %d\n", in->newfid);
	}

	fid = in->fid;
	fid1 = in->newfid;

	f1 = 0;
	f2 = 0;
	if(fid < fid1) {
		f1 = filep(cp, fid, 0);
		f2 = filep(cp, fid1, 1);
	} else
	if(fid1 < fid) {
		f2 = filep(cp, fid1, 1);
		f1 = filep(cp, fid, 0);
	}
	if(!f1 || !f2) {
		ou->err = Efid;
		goto out;
	}


	f2->fs = f1->fs;
	f2->addr = f1->addr;
	f2->open = f1->open & ~FREMOV;
	f2->uid = f1->uid;
	f2->slot = f1->slot;
	f2->qid = f1->qid;

	freewp(f2->wpath);
	lock(&wpathlock);
	f2->wpath = f1->wpath;
	for(p = f2->wpath; p; p = p->up)
		p->refs++;
	unlock(&wpathlock);

out:
	ou->fid = fid;
	if(f1)
		qunlock(f1);
	if(f2) {
		qunlock(f2);
		if(ou->err)
			freefp(f2);
	}
}

static void
f_walk(Chan *cp, Fcall *in, Fcall *ou)
{
	Iobuf *p, *p1;
	Dentry *d, *d1;
	File *f;
	Wpath *w;
	int slot;
	Off addr, qpath;

	if(CHAT(cp)) {
		print("c_walk %d\n", cp->chan);
		print("	fid = %d\n", in->fid);
		print("	name = %s\n", in->name);
	}

	ou->fid = in->fid;
	ou->qid = QID9P1(0,0);
	p = 0;
	f = filep(cp, in->fid, 0);
	if(!f) {
		ou->err = Efid;
		goto out;
	}
	p = getbuf(f->fs->dev, f->addr, Bread);
	d = getdir(p, f->slot);
	if(!d || checktag(p, Tdir, QPNONE) || !(d->mode & DALLOC)) {
		ou->err = Ealloc;
		goto out;
	}
	if(!(d->mode & DDIR)) {
		ou->err = Edir1;
		goto out;
	}
	if(ou->err = mkqidcmp(&f->qid, d))
		goto out;
	if(cp != cons.chan && iaccess(f, d, DEXEC)) {
		ou->err = Eaccess;
		goto out;
	}
	accessdir(p, d, FREAD, f->uid);
	if(strcmp(in->name, ".") == 0)
		goto setdot;
	if(strcmp(in->name, "..") == 0) {
		if(f->wpath == 0)
			goto setdot;
		putbuf(p);
		p = 0;
		addr = f->wpath->addr;
		slot = f->wpath->slot;
		p1 = getbuf(f->fs->dev, addr, Bread);
		d1 = getdir(p1, slot);
		if(!d1 || checktag(p1, Tdir, QPNONE) || !(d1->mode & DALLOC)) {
			if(p1)
				putbuf(p1);
			ou->err = Ephase;
			goto out;
		}
		lock(&wpathlock);
		f->wpath->refs--;
		f->wpath = f->wpath->up;
		unlock(&wpathlock);
		goto found;
	}
	for(addr=0;; addr++) {
		if(p == 0) {
			p = getbuf(f->fs->dev, f->addr, Bread);
			d = getdir(p, f->slot);
			if(!d || checktag(p, Tdir, QPNONE) || !(d->mode & DALLOC)) {
				ou->err = Ealloc;
				goto out;
			}
		}
		qpath = d->qid.path;
		p1 = dnodebuf1(p, d, addr, 0, f->uid);
		p = 0;
		if(!p1 || checktag(p1, Tdir, qpath) ) {
			if(p1)
				putbuf(p1);
			ou->err = Eentry;
			goto out;
		}
		for(slot=0; slot<DIRPERBUF; slot++) {
			d1 = getdir(p1, slot);
			if(!(d1->mode & DALLOC))
				continue;
			if(strncmp(in->name, d1->name, sizeof(in->name)) != 0)
				continue;
			/*
			 * update walk path
			 */
			w = newwp();
			if(!w) {
				ou->err = Ewalk;
				putbuf(p1);
				goto out;
			}
			w->addr = f->addr;
			w->slot = f->slot;
			w->up = f->wpath;
			f->wpath = w;
			slot += DIRPERBUF*addr;
			goto found;
		}
		putbuf(p1);
	}

found:
	f->addr = p1->addr;
	mkqid(&f->qid, d1, 1);
	putbuf(p1);
	f->slot = slot;

setdot:
	mkqid9p1(&ou->qid, &f->qid);
	f->open = 0;

out:
	if(p)
		putbuf(p);
	if(f)
		qunlock(f);
}

static void
f_open(Chan *cp, Fcall *in, Fcall *ou)
{
	Iobuf *p;
	Dentry *d;
	File *f;
	Tlock *t;
	Qid qid;
	int ro, fmod, wok;

	if(CHAT(cp)) {
		print("c_open %d\n", cp->chan);
		print("	fid = %d\n", in->fid);
		print("	mode = %o\n", in->mode);
	}

	wok = 0;
	if(cp == cons.chan || writeallow)
		wok = 1;

	p = 0;
	f = filep(cp, in->fid, 0);
	if(!f) {
		ou->err = Efid;
		goto out;
	}

	/*
	 * if remove on close, check access here
	 */
	ro = f->fs->dev->type == Devro;
	if(in->mode & ORCLOSE) {
		if(ro) {
			ou->err = Eronly;
			goto out;
		}
		/*
		 * check on parent directory of file to be deleted
		 */
		if(f->wpath == 0 || f->wpath->addr == f->addr) {
			ou->err = Ephase;
			goto out;
		}
		p = getbuf(f->fs->dev, f->wpath->addr, Bread);
		d = getdir(p, f->wpath->slot);
		if(!d || checktag(p, Tdir, QPNONE) || !(d->mode & DALLOC)) {
			ou->err = Ephase;
			goto out;
		}
		if(iaccess(f, d, DWRITE)) {
			ou->err = Eaccess;
			goto out;
		}
		putbuf(p);
	}
	p = getbuf(f->fs->dev, f->addr, Bread);
	d = getdir(p, f->slot);
	if(!d || checktag(p, Tdir, QPNONE) || !(d->mode & DALLOC)) {
		ou->err = Ealloc;
		goto out;
	}
	if(ou->err = mkqidcmp(&f->qid, d))
		goto out;
	mkqid(&qid, d, 1);
	switch(in->mode & 7) {

	case OREAD:
		if(iaccess(f, d, DREAD) && !wok)
			goto badaccess;
		fmod = FREAD;
		break;

	case OWRITE:
		if((d->mode & DDIR) ||
		   (iaccess(f, d, DWRITE) && !wok))
			goto badaccess;
		if(ro) {
			ou->err = Eronly;
			goto out;
		}
		fmod = FWRITE;
		break;

	case ORDWR:
		if((d->mode & DDIR) ||
		   (iaccess(f, d, DREAD) && !wok) ||
		   (iaccess(f, d, DWRITE) && !wok))
			goto badaccess;
		if(ro) {
			ou->err = Eronly;
			goto out;
		}
		fmod = FREAD+FWRITE;
		break;

	case OEXEC:
		if((d->mode & DDIR) ||
		   (iaccess(f, d, DEXEC) && !wok))
			goto badaccess;
		fmod = FREAD;
		break;

	default:
		ou->err = Emode;
		goto out;
	}
	if(in->mode & OTRUNC) {
		if((d->mode & DDIR) ||
		   (iaccess(f, d, DWRITE) && !wok))
			goto badaccess;
		if(ro) {
			ou->err = Eronly;
			goto out;
		}
	}
	t = 0;
	if(d->mode & DLOCK) {
		t = tlocked(p, d);
		if(t == nil) {
			ou->err = Elocked;
			goto out;
		}
	}
	if(in->mode & ORCLOSE)
		fmod |= FREMOV;
	f->open = fmod;
	if(in->mode & OTRUNC)
		if(!(d->mode & DAPND)) {
			dtrunc(p, d, f->uid);
			qid.vers = d->qid.version;
		}
	f->tlock = t;
	if(t)
		t->file = f;
	f->lastra = 1;
	mkqid9p1(&ou->qid, &qid);
	goto out;

badaccess:
	ou->err = Eaccess;
	f->open = 0;

out:
	if(p)
		putbuf(p);
	if(f)
		qunlock(f);
	ou->fid = in->fid;
}

static void
f_create(Chan *cp, Fcall *in, Fcall *ou)
{
	Iobuf *p, *p1;
	Dentry *d, *d1;
	File *f;
	int slot, slot1, fmod, wok;
	Off addr, addr1, path;
	Qid qid;
	Tlock *t;
	Wpath *w;

	if(CHAT(cp)) {
		print("c_create %d\n", cp->chan);
		print("	fid = %d\n", in->fid);
		print("	name = %s\n", in->name);
		print("	perm = %lx+%lo\n", (in->perm>>28)&0xf,
				in->perm&0777);
		print("	mode = %o\n", in->mode);
	}

	wok = 0;
	if(cp == cons.chan || writeallow)
		wok = 1;

	p = 0;
	f = filep(cp, in->fid, 0);
	if(!f) {
		ou->err = Efid;
		goto out;
	}
	if(f->fs->dev->type == Devro) {
		ou->err = Eronly;
		goto out;
	}

	p = getbuf(f->fs->dev, f->addr, Bread);
	d = getdir(p, f->slot);
	if(!d || checktag(p, Tdir, QPNONE) || !(d->mode & DALLOC)) {
		ou->err = Ealloc;
		goto out;
	}
	if(ou->err = mkqidcmp(&f->qid, d))
		goto out;
	if(!(d->mode & DDIR)) {
		ou->err = Edir2;
		goto out;
	}
	if(iaccess(f, d, DWRITE) && !wok) {
		ou->err = Eaccess;
		goto out;
	}
	accessdir(p, d, FREAD, f->uid);
	if(!strncmp(in->name, ".", sizeof(in->name)) ||
	   !strncmp(in->name, "..", sizeof(in->name))) {
		ou->err = Edot;
		goto out;
	}
	if(checkname(in->name)) {
		ou->err = Ename;
		goto out;
	}
	addr1 = 0;
	slot1 = 0;	/* set */
	for(addr=0;; addr++) {
		p1 = dnodebuf(p, d, addr, 0, f->uid);
		if(!p1) {
			if(addr1)
				break;
			p1 = dnodebuf(p, d, addr, Tdir, f->uid);
		}
		if(p1 == 0) {
			ou->err = Efull;
			goto out;
		}
		if(checktag(p1, Tdir, d->qid.path)) {
			putbuf(p1);
			goto phase;
		}
		for(slot=0; slot<DIRPERBUF; slot++) {
			d1 = getdir(p1, slot);
			if(!(d1->mode & DALLOC)) {
				if(!addr1) {
					addr1 = p1->addr;
					slot1 = slot + addr*DIRPERBUF;
				}
				continue;
			}
			if(!strncmp(in->name, d1->name, sizeof(in->name))) {
				putbuf(p1);
				ou->err = Eexist;
				goto out;
			}
		}
		putbuf(p1);
	}
	switch(in->mode & 7) {
	case OEXEC:
	case OREAD:		/* seems only useful to make directories */
		fmod = FREAD;
		break;

	case OWRITE:
		fmod = FWRITE;
		break;

	case ORDWR:
		fmod = FREAD+FWRITE;
		break;

	default:
		ou->err = Emode;
		goto out;
	}
	if(in->perm & PDIR)
		if((in->mode & OTRUNC) || (in->perm & PAPND) || (fmod & FWRITE))
			goto badaccess;
	/*
	 * do it
	 */
	path = qidpathgen(f->fs->dev);
	p1 = getbuf(f->fs->dev, addr1, Bread|Bimm|Bmod);
	d1 = getdir(p1, slot1);
	if(!d1 || checktag(p1, Tdir, d->qid.path)) {
		if(p1)
			putbuf(p1);
		goto phase;
	}
	if(d1->mode & DALLOC) {
		putbuf(p1);
		goto phase;
	}

	strncpy(d1->name, in->name, sizeof(in->name));
	if(cp == cons.chan) {
		d1->uid = cons.uid;
		d1->gid = cons.gid;
	} else {
		d1->uid = f->uid;
		d1->gid = d->gid;
		in->perm &= d->mode | ~0666;
		if(in->perm & PDIR)
			in->perm &= d->mode | ~0777;
	}
	d1->qid.path = path;
	d1->qid.version = 0;
	d1->mode = DALLOC | (in->perm & 0777);
	if(in->perm & PDIR) {
		d1->mode |= DDIR;
		d1->qid.path |= QPDIR;
	}
	if(in->perm & PAPND)
		d1->mode |= DAPND;
	t = 0;
	if(in->perm & PLOCK) {
		d1->mode |= DLOCK;
		t = tlocked(p1, d1);
		/* if nil, out of tlock structures */
	}
	accessdir(p1, d1, FWRITE, f->uid);
	mkqid(&qid, d1, 0);
	putbuf(p1);
	accessdir(p, d, FWRITE, f->uid);

	/*
	 * do a walk to new directory entry
	 */
	w = newwp();
	if(!w) {
		ou->err = Ewalk;
		goto out;
	}
	w->addr = f->addr;
	w->slot = f->slot;
	w->up = f->wpath;
	f->wpath = w;
	f->qid = qid;
	f->tlock = t;
	if(t)
		t->file = f;
	f->lastra = 1;
	if(in->mode & ORCLOSE)
		fmod |= FREMOV;
	f->open = fmod;
	f->addr = addr1;
	f->slot = slot1;
	mkqid9p1(&ou->qid, &qid);
	goto out;

badaccess:
	ou->err = Eaccess;
	goto out;

phase:
	ou->err = Ephase;

out:
	if(p)
		putbuf(p);
	if(f)
		qunlock(f);
	ou->fid = in->fid;
}

static void
f_read(Chan *cp, Fcall *in, Fcall *ou)
{
	Iobuf *p, *p1;
	File *f;