diff --git a/src/cmd/vac/cache.c b/src/cmd/vac/cache.c
new file mode 100644
index 0000000..fc34d68
--- /dev/null
+++ b/src/cmd/vac/cache.c
@@ -0,0 +1,876 @@
+#include "stdinc.h"
+#include "vac.h"
+#include "dat.h"
+#include "fns.h"
+
+typedef struct Label Label;
+
+enum {
+	BadHeap = ~0,
+};
+
+/*
+ * the plan is to store data to the cache in c->size blocks
+ * with the block zero extended to fill it out.  When writing to
+ * venti, the block will be zero truncated.  The walker will also check
+ * that the block fits within psize or dsize as the case may be.
+ */
+
+struct Cache
+{
+	VtLock	*lk;
+	VtSession *z;
+	u32int	now;			/* ticks for usage timestamps */
+	int	size;			/* max. size of any block; allocated to each block */
+	Lump	**heads;		/* hash table for finding address */
+	int	nheap;			/* number of available victims */
+	Lump	**heap;			/* heap for locating victims */
+	long	nblocks;		/* number of blocks allocated */
+	Lump	*blocks;		/* array of block descriptors */
+	u8int	*mem;			/* memory for all block descriptors */
+	Lump	*free;			/* free list of lumps */
+
+	long hashSize;
+};
+
+/*
+ * the tag for a block is hash(index, parent tag)
+ */
+
+struct Label {
+	uchar gen[4];
+	uchar state;
+	uchar type;		/* top bit indicates it is part of a directory */
+	uchar tag[4];		/* tag of file it is in */
+};
+
+
+static char ENoDir[] = "directory entry is not allocated";
+
+static void fixHeap(int si, Lump *b);
+static int upHeap(int i, Lump *b);
+static int downHeap(int i, Lump *b);
+static char	*lumpState(int);
+static void	lumpSetState(Lump *u, int state);
+
+Cache *
+cacheAlloc(VtSession *z, int blockSize, long nblocks)
+{
+	int i;
+	Cache *c;
+	Lump *b;
+
+	c = vtMemAllocZ(sizeof(Cache));
+	
+	c->lk = vtLockAlloc();
+	c->z = z;
+	c->size = blockSize;
+	c->nblocks = nblocks;
+	c->hashSize = nblocks;
+	c->heads = vtMemAllocZ(c->hashSize*sizeof(Lump*));
+	c->heap = vtMemAllocZ(nblocks*sizeof(Lump*));
+	c->blocks = vtMemAllocZ(nblocks*sizeof(Lump));
+	c->mem = vtMemAllocZ(nblocks * blockSize);
+	for(i = 0; i < nblocks; i++){
+		b = &c->blocks[i];
+		b->lk = vtLockAlloc();
+		b->c = c;
+		b->data = &c->mem[i * blockSize];
+		b->addr = i+1;
+		b->state = LumpFree;
+		b->heap = BadHeap;
+		b->next = c->free;
+		c->free = b;
+	}
+	c->nheap = 0;
+
+	return c;
+}
+
+long
+cacheGetSize(Cache *c)
+{
+	return c->nblocks;
+}
+
+int
+cacheGetBlockSize(Cache *c)
+{
+	return c->size;
+}
+
+int
+cacheSetSize(Cache *c, long nblocks)
+{
+	USED(c);
+	USED(nblocks);
+	return 0;
+}
+
+void
+cacheFree(Cache *c)
+{
+	int i;
+
+	for(i = 0; i < c->nblocks; i++){
+		assert(c->blocks[i].ref == 0);
+		vtLockFree(c->blocks[i].lk);
+	}
+	vtMemFree(c->heads);
+	vtMemFree(c->blocks);
+	vtMemFree(c->mem);
+	vtMemFree(c);
+}
+
+static u32int
+hash(Cache *c, uchar score[VtScoreSize], int type)
+{
+	u32int h;
+	uchar *p = score + VtScoreSize-4;
+
+	h = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
+	h += type;
+	return h % c->hashSize;
+}
+
+static void
+findLump(Cache *c, Lump *bb)
+{
+	Lump *b, *last;
+	int h;
+
+	last = nil;
+	h = hash(c, bb->score, bb->type);
+	for(b = c->heads[h]; b != nil; b = b->next){
+		if(last != b->prev)
+			vtFatal("bad prev link");
+		if(b == bb)
+			return;
+		last = b;
+	}
+	vtFatal("block missing from hash table");
+}
+
+void
+cacheCheck(Cache *c)
+{
+	u32int size, now;
+	int i, k, refed, free;
+	static uchar zero[VtScoreSize];
+	Lump *p;
+
+	size = c->size;
+	now = c->now;
+
+	free = 0;
+	for(p=c->free; p; p=p->next)
+		free++;
+	for(i = 0; i < c->nheap; i++){
+		if(c->heap[i]->heap != i)
+			vtFatal("mis-heaped at %d: %d", i, c->heap[i]->heap);
+		if(i > 0 && c->heap[(i - 1) >> 1]->used2 - now > c->heap[i]->used2 - now)
+			vtFatal("bad heap ordering");
+		k = (i << 1) + 1;
+		if(k < c->nheap && c->heap[i]->used2 - now > c->heap[k]->used2 - now)
+			vtFatal("bad heap ordering");
+		k++;
+		if(k < c->nheap && c->heap[i]->used2 - now > c->heap[k]->used2 - now)
+			vtFatal("bad heap ordering");
+	}
+
+	refed = 0;
+	for(i = 0; i < c->nblocks; i++){
+		if(c->blocks[i].data != &c->mem[i * size])
+			vtFatal("mis-blocked at %d", i);
+		if(c->blocks[i].ref && c->blocks[i].heap == BadHeap){
+			refed++;
+		}
+		if(memcmp(zero, c->blocks[i].score, VtScoreSize))
+			findLump(c, &c->blocks[i]);
+	}
+if(refed > 0)fprint(2, "cacheCheck: nheap %d refed %d free %d\n", c->nheap, refed, free);
+	assert(c->nheap + refed + free == c->nblocks);
+	refed = 0;
+	for(i = 0; i < c->nblocks; i++){
+		if(c->blocks[i].ref) {
+if(1)fprint(2, "%d %V %d %s\n", c->blocks[i].type, c->blocks[i].score, c->blocks[i].ref, lumpState(c->blocks[i].state));
+			refed++;
+		}
+	}
+if(refed > 0)fprint(2, "cacheCheck: in used %d\n", refed);
+}
+
+/*
+ * delete an arbitrary block from the heap
+ */
+static void
+delHeap(Lump *db)
+{
+	fixHeap(db->heap, db->c->heap[--db->c->nheap]);
+	db->heap = BadHeap;
+}
+
+static void
+fixHeap(int si, Lump *b)
+{
+	int i;
+
+	i = upHeap(si, b);
+	if(i == si)
+		downHeap(i, b);
+}
+
+static int
+upHeap(int i, Lump *b)
+{
+	Lump *bb;
+	u32int now;
+	int p;
+	Cache *c;
+	
+	c = b->c;
+	now = c->now;
+	for(; i != 0; i = p){
+		p = (i - 1) >> 1;
+		bb = c->heap[p];
+		if(b->used2 - now >= bb->used2 - now)
+			break;
+		c->heap[i] = bb;
+		bb->heap = i;
+	}
+	c->heap[i] = b;
+	b->heap = i;
+
+	return i;
+}
+
+static int
+downHeap(int i, Lump *b)
+{
+	Lump *bb;
+	u32int now;
+	int k;
+	Cache *c;
+	
+	c = b->c;
+	now = c->now;
+	for(; ; i = k){
+		k = (i << 1) + 1;
+		if(k >= c->nheap)
+			break;
+		if(k + 1 < c->nheap && c->heap[k]->used2 - now > c->heap[k + 1]->used2 - now)
+			k++;
+		bb = c->heap[k];
+		if(b->used2 - now <= bb->used2 - now)
+			break;
+		c->heap[i] = bb;
+		bb->heap = i;
+	}
+	c->heap[i] = b;
+	b->heap = i;
+	return i;
+}
+
+
+/* called with c->lk held */
+Lump *
+cacheBumpLump(Cache *c)
+{
+	Lump *b;
+
+	/*
+	 * missed: locate the block with the oldest second to last use.
+	 * remove it from the heap, and fix up the heap.
+	 */
+	if(c->free) {
+		b = c->free;
+		c->free = b->next;
+	} else {
+		for(;;){
+			if(c->nheap == 0) {
+				cacheCheck(c);
+				assert(0);
+				return nil;
+			}
+			b = c->heap[0];
+			delHeap(b);
+			if(b->ref == 0)
+				break;
+		}
+
+		/*
+		 * unchain the block from hash chain
+		 */
+		if(b->prev == nil)
+			c->heads[hash(c, b->score, b->type)] = b->next;
+		else
+			b->prev->next = b->next;
+		if(b->next != nil)
+			b->next->prev = b->prev;
+
+	}
+
+	/*
+	 * the new block has no last use, so assume it happens sometime in the middle
+	 */
+	b->used = (b->used2 + c->now) / 2;
+	b->asize = 0;
+
+	return b;
+}
+
+Lump *
+cacheAllocLump(Cache *c, int type, int size, int dir)
+{
+	Lump *b;
+	ulong h;
+
+	assert(size <= c->size);
+
+again:
+	vtLock(c->lk);
+	b = cacheBumpLump(c);
+	if(b == nil) {
+		vtUnlock(c->lk);
+fprint(2, "cache is full\n");
+		/* XXX should be better */
+		sleep(100);
+		goto again;
+	}
+
+	vtLock(b->lk);
+
+	assert(b->ref == 0);
+	b->ref++;
+	b->used2 = b->used;
+	b->used = c->now++;
+
+	/* convert addr into score */
+	memset(b->score, 0, VtScoreSize-4);
+	b->score[VtScoreSize-4] = b->addr>>24;
+	b->score[VtScoreSize-3] = b->addr>>16;
+	b->score[VtScoreSize-2] = b->addr>>8;
+	b->score[VtScoreSize-1] = b->addr;
+	
+	b->dir = dir;
+	b->type = type;
+	b->gen = 0;
+	b->asize = size;
+	b->state = LumpFree;
+
+	h = hash(c, b->score, b->type);
+
+	/* chain onto correct hash */
+	b->next = c->heads[h];
+	c->heads[h] = b;
+	if(b->next != nil)
+		b->next->prev = b;
+	b->prev = nil;
+
+	vtUnlock(c->lk);
+
+	vtZeroExtend(type, b->data, 0, size);
+	lumpSetState(b, LumpActive);
+
+	return b;
+}
+
+int
+scoreIsLocal(uchar score[VtScoreSize])
+{
+	static uchar zero[VtScoreSize];
+	
+	return memcmp(score, zero, VtScoreSize-4) == 0;
+}
+
+Lump *
+cacheGetLump(Cache *c, uchar score[VtScoreSize], int type, int size)
+{
+	Lump *b;
+	ulong h;
+	int n;
+	static uchar zero[VtScoreSize];
+
+	assert(size <= c->size);
+
+	h = hash(c, score, type);
+
+again:
+	/*
+	 * look for the block in the cache
+	 */
+	vtLock(c->lk);
+	for(b = c->heads[h]; b != nil; b = b->next){
+		if(memcmp(b->score, score, VtScoreSize) == 0 && b->type == type)
+			goto found;
+	}
+
+	/* should not be looking for a temp block */
+	if(scoreIsLocal(score)) {
+		if(memcmp(score, zero, VtScoreSize) == 0)
+			vtSetError("looking for zero score");
+		else
+			vtSetError("missing local block");
+		vtUnlock(c->lk);
+		return nil;
+	}
+
+	b = cacheBumpLump(c);
+	if(b == nil) {
+		vtUnlock(c->lk);
+		sleep(100);
+		goto again;
+	}
+
+	/* chain onto correct hash */
+	b->next = c->heads[h];
+	c->heads[h] = b;
+	if(b->next != nil)
+		b->next->prev = b;
+	b->prev = nil;
+
+	memmove(b->score, score, VtScoreSize);	
+	b->type = type;
+	b->state = LumpFree;
+
+found:
+	b->ref++;
+	b->used2 = b->used;
+	b->used = c->now++;
+	if(b->heap != BadHeap)
+		fixHeap(b->heap, b);
+
+	vtUnlock(c->lk);
+
+	vtLock(b->lk);
+	if(b->state != LumpFree)
+		return b;
+	
+	n = vtRead(c->z, score, type, b->data, size);
+	if(n < 0) {
+		lumpDecRef(b, 1);
+		return nil;
+	}
+	if(!vtSha1Check(score, b->data, n)) {
+		vtSetError("vtSha1Check failed");
+		lumpDecRef(b, 1);
+		return nil;
+	}
+	vtZeroExtend(type, b->data, n, size);
+	b->asize = size;
+	lumpSetState(b, LumpVenti);
+
+	return b;
+}
+
+static char *
+lumpState(int state)
+{
+	switch(state) {
+	default:
+		return "Unknown!!";
+	case LumpFree:
+		return "Free";
+	case LumpActive:
+		return "Active";
+	case LumpSnap:
+		return "Snap";
+	case LumpZombie:
+		return "Zombie";
+	case LumpVenti:
+		return "Venti";
+	}
+}
+
+static void
+lumpSetState(Lump *u, int state)
+{
+//	if(u->state != LumpFree)
+//		fprint(2, "%V: %s -> %s\n", u->score, lumpState(u->state), lumpState(state));
+	u->state = state;
+}
+	
+int
+lumpGetScore(Lump *u, int offset, uchar score[VtScoreSize])
+{
+	uchar *sp;
+	VtRoot root;
+	VtEntry dir;
+
+	vtLock(u->lk);
+
+	switch(u->type) {
+	default:
+		vtSetError("bad type");
+		goto Err;
+	case VtPointerType0:
+	case VtPointerType1:
+	case VtPointerType2:
+	case VtPointerType3:
+	case VtPointerType4:
+	case VtPointerType5:
+	case VtPointerType6:
+		if((offset+1)*VtScoreSize > u->asize)
+			sp = nil;
+		else
+			sp = u->data + offset*VtScoreSize;
+		break;
+	case VtRootType:
+		if(u->asize < VtRootSize) {
+			vtSetError("runt root block");
+			goto Err;
+		}
+		if(!vtRootUnpack(&root, u->data))
+			goto Err;
+		sp = root.score;
+		break;
+	case VtDirType:
+		if((offset+1)*VtEntrySize > u->asize) {
+			vtSetError(ENoDir);
+			goto Err;
+		}
+		if(!vtEntryUnpack(&dir, u->data, offset))
+			goto Err;
+		if(!dir.flags & VtEntryActive) {
+			vtSetError(ENoDir);
+			goto Err;
+		}
+		sp = dir.score;
+		break;
+	}
+
+	if(sp == nil)
+		memmove(score, vtZeroScore, VtScoreSize);
+	else
+		memmove(score, sp, VtScoreSize);
+
+	vtUnlock(u->lk);
+	return !scoreIsLocal(score);
+Err:
+	vtUnlock(u->lk);
+	return 0;
+}
+
+Lump *
+lumpWalk(Lump *u, int offset, int type, int size, int readOnly, int lock)
+{
+	Lump *v, *vv;
+	Cache *c;
+	uchar score[VtScoreSize], *sp;
+	VtRoot root;
+	VtEntry dir;
+	int split, isdir;
+
+	c = u->c;
+	vtLock(u->lk);
+
+Again:
+	v = nil;
+	vv = nil;
+
+	isdir = u->dir;
+	switch(u->type) {
+	default:
+		vtSetError("bad type");
+		goto Err;
+	case VtPointerType0:
+	case VtPointerType1:
+	case VtPointerType2:
+	case VtPointerType3:
+	case VtPointerType4:
+	case VtPointerType5:
+	case VtPointerType6:
+		if((offset+1)*VtScoreSize > u->asize)
+			sp = nil;
+		else
+			sp = u->data + offset*VtScoreSize;
+		break;
+	case VtRootType:
+		if(u->asize < VtRootSize) {
+			vtSetError("runt root block");
+			goto Err;
+		}
+		if(!vtRootUnpack(&root, u->data))
+			goto Err;
+		sp = root.score;
+		break;
+	case VtDirType:
+		if((offset+1)*VtEntrySize > u->asize) {
+			vtSetError(ENoDir);
+			goto Err;
+		}
+		if(!vtEntryUnpack(&dir, u->data, offset))
+			goto Err;
+		if(!(dir.flags & VtEntryActive)) {
+			vtSetError(ENoDir);
+			goto Err;
+		}
+		isdir = (dir.flags & VtEntryDir) != 0;
+//		sp = dir.score;
+		sp = u->data + offset*VtEntrySize + 20;
+		break;
+	}
+
+	if(sp == nil)
+		memmove(score, vtZeroScore, VtScoreSize);
+	else
+		memmove(score, sp, VtScoreSize);
+	
+	vtUnlock(u->lk);
+
+
+if(0)fprint(2, "lumpWalk: %V:%s %d:%d-> %V:%d\n", u->score, lumpState(u->state), u->type, offset, score, type);
+	v = cacheGetLump(c, score, type, size);
+	if(v == nil)
+		return nil;
+
+	split = 1;
+	if(readOnly)
+		split = 0;
+
+	switch(v->state) {
+	default:
+		assert(0);
+	case LumpFree:
+fprint(2, "block is free %V!\n", v->score);
+		vtSetError("phase error");
+		goto Err2;
+	case LumpActive:	
+		if(v->gen < u->gen) {
+print("LumpActive gen\n");
+			lumpSetState(v, LumpSnap);
+			v->gen = u->gen;
+		} else
+			split = 0;
+		break;
+	case LumpSnap:
+	case LumpVenti:
+		break;
+	}
+	
+	/* easy case */
+	if(!split) {
+		if(!lock)
+			vtUnlock(v->lk);
+		return v;
+	}
+
+	if(sp == nil) {
+		vtSetError("bad offset");
+		goto Err2;
+	}
+
+	vv = cacheAllocLump(c, v->type, size, isdir);
+	/* vv is locked */
+	vv->gen = u->gen;
+	memmove(vv->data, v->data, v->asize);
+if(0)fprint(2, "split %V into %V\n", v->score, vv->score);
+
+	lumpDecRef(v, 1);
+	v = nil;
+
+	vtLock(u->lk);
+	if(u->state != LumpActive) {
+		vtSetError("bad parent state: can not happen");
+		goto Err;
+	}
+
+	/* check that nothing changed underfoot */
+	if(memcmp(sp, score, VtScoreSize) != 0) {
+		lumpDecRef(vv, 1);
+fprint(2, "lumpWalk: parent changed under foot\n");
+		goto Again;
+	}
+
+	/* XXX - hold Active blocks up - will go eventually */
+	lumpIncRef(vv);
+
+	/* change the parent */
+	memmove(sp, vv->score, VtScoreSize);
+	
+	vtUnlock(u->lk);
+	
+	if(!lock)
+		vtUnlock(vv->lk);
+	return vv;
+Err:
+	vtUnlock(u->lk);
+	lumpDecRef(v, 0);
+	lumpDecRef(vv, 1);
+	return nil;
+Err2:
+	lumpDecRef(v, 1);
+	return nil;
+	
+}
+
+void
+lumpFreeEntry(Lump *u, int entry)
+{
+	uchar score[VtScoreSize];
+	int type;
+	ulong gen;
+	VtEntry dir;
+	Cache *c;
+
+	c = u->c;
+	vtLock(u->lk);
+	if(u->state == LumpVenti)
+		goto Exit;
+
+	switch(u->type) {
+	default:
+		fprint(2, "freeing bad lump type: %d\n", u->type);
+		return;
+	case VtPointerType0:
+		if((entry+1)*VtScoreSize > u->asize)
+			goto Exit;
+		memmove(score, u->data + entry*VtScoreSize, VtScoreSize);
+		memmove(u->data + entry*VtScoreSize, vtZeroScore, VtScoreSize);
+		type = u->dir?VtDirType:VtDataType;
+		break;
+	case VtPointerType1:
+	case VtPointerType2:
+	case VtPointerType3:
+	case VtPointerType4:
+	case VtPointerType5:
+	case VtPointerType6:
+		if((entry+1)*VtScoreSize > u->asize)
+			goto Exit;
+		memmove(score, u->data + entry*VtScoreSize, VtScoreSize);
+		memmove(u->data + entry*VtScoreSize, vtZeroScore, VtScoreSize);
+		type = u->type-1;
+		break;
+	case VtDirType:
+		if((entry+1)*VtEntrySize > u->asize)
+			goto Exit;
+		if(!vtEntryUnpack(&dir, u->data, entry))
+			goto Exit;
+		if(!dir.flags & VtEntryActive)
+			goto Exit;
+		gen = dir.gen;
+		if(gen != ~0)
+			gen++;
+		if(dir.depth == 0)
+			type = (dir.flags&VtEntryDir)?VtDirType:VtDataType;
+		else
+			type = VtPointerType0 + dir.depth - 1;
+		memmove(score, dir.score, VtScoreSize);
+		memset(&dir, 0, sizeof(dir));
+		dir.gen = gen;
+		vtEntryPack(&dir, u->data, entry);
+		break;
+	case VtDataType:
+		type = VtErrType;
+		break;
+	}
+	vtUnlock(u->lk);
+	if(type == VtErrType || !scoreIsLocal(score))
+		return;
+
+	u = cacheGetLump(c, score, type, c->size);
+	if(u == nil)
+		return;
+	lumpDecRef(u, 1);
+	/* XXX remove extra reference */
+	lumpDecRef(u, 0);
+	return;
+Exit:
+	vtUnlock(u->lk);
+	return;
+
+}
+
+void
+lumpCleanup(Lump *u)
+{
+	int i, n;
+
+	switch(u->type) {
+	default:
+		return;
+	case VtPointerType0:
+	case VtPointerType1:
+	case VtPointerType2:
+	case VtPointerType3:
+	case VtPointerType4:
+	case VtPointerType5:
+	case VtPointerType6:
+		n = u->asize/VtScoreSize;
+		break;	
+	case VtDirType:
+		n = u->asize/VtEntrySize;
+		break;
+	}
+
+	for(i=0; i<n; i++)
+		lumpFreeEntry(u, i);
+}
+
+
+void
+lumpDecRef(Lump *b, int unlock)
+{
+	int i;
+	Cache *c;
+
+	if(b == nil)
+		return;
+
+	if(unlock)
+		vtUnlock(b->lk);
+
+	c = b->c;
+	vtLock(c->lk);
+	if(--b->ref > 0) {
+		vtUnlock(c->lk);
+		return;
+	}
+	assert(b->ref == 0);
+
+	switch(b->state) {
+	default:
+		fprint(2, "bad state: %s\n", lumpState(b->state));
+		assert(0);
+	case LumpActive:
+		/* hack - but will do for now */
+		b->ref++;
+		vtUnlock(c->lk);
+		lumpCleanup(b);
+		vtLock(c->lk);
+		b->ref--;
+		lumpSetState(b, LumpFree);
+		break;
+	case LumpZombie:
+		lumpSetState(b, LumpFree);
+		break;
+	case LumpFree:
+	case LumpVenti:
+		break;
+	}
+
+	/*
+	 * reinsert in the free heap
+	 */
+	if(b->heap == BadHeap) {
+		i = upHeap(c->nheap++, b);
+		c->heap[i] = b;
+		b->heap = i;
+	}
+
+	vtUnlock(c->lk);
+}
+
+Lump *
+lumpIncRef(Lump *b)
+{
+	Cache *c;
+
+	c = b->c;
+
+	vtLock(c->lk);
+	assert(b->ref > 0);
+	b->ref++;
+	vtUnlock(c->lk);
+	return b;
+}
diff --git a/src/cmd/vac/dat.h b/src/cmd/vac/dat.h
new file mode 100644
index 0000000..a468668
--- /dev/null
+++ b/src/cmd/vac/dat.h
@@ -0,0 +1,156 @@
+typedef struct Source Source;
+typedef struct VacFile VacFile;
+typedef struct MetaBlock MetaBlock;
+typedef struct MetaEntry MetaEntry;
+typedef struct Lump Lump;
+typedef struct Cache Cache;
+typedef struct Super Super;
+
+enum {
+	NilBlock	= (~0UL),
+	MaxBlock	= (1UL<<31),
+};
+
+
+struct VacFS {
+	int ref;
+	
+	/* need a read write lock? */
+
+	uchar score[VtScoreSize];
+	VacFile *root;
+	
+	VtSession *z;
+	int readOnly;
+	int bsize;		/* maximum block size */
+	uvlong qid;		/* next qid */
+	Cache *cache;
+};
+
+
+struct Source {
+	VtLock *lk;
+
+	Cache *cache;	/* immutable */
+	int readOnly;	/* immutable */
+
+	Lump *lump;	/* lump containing venti dir entry */
+	ulong block;	/* block number within parent: immutable */
+	int entry;	/* which entry in the block: immutable */
+
+	/* most of a VtEntry, except the score */
+	ulong gen;	/* generation: immutable */
+	int dir;	/* dir flags: immutable */
+	int depth;	/* number of levels of pointer blocks */
+	int psize;	/* pointer block size: immutable */
+	int dsize;	/* data block size: immutable */
+	uvlong size;	/* size in bytes of file */
+
+	int epb;	/* dir entries per block = dize/VtEntrySize: immutable */
+};
+
+struct MetaEntry {
+	uchar *p;
+	ushort size;
+};
+
+struct MetaBlock {
+	int maxsize;		/* size of block */
+	int size;		/* size used */
+	int free;		/* free space within used size */
+	int maxindex;		/* entries allocated for table */
+	int nindex;		/* amount of table used */
+	int unbotch;
+	uchar *buf;
+};
+
+/*
+ * contains a one block buffer
+ * to avoid problems of the block changing underfoot
+ * and to enable an interface that supports unget.
+ */
+struct VacDirEnum {
+	VacFile *file;
+	
+	ulong block;	/* current block */
+	MetaBlock mb;	/* parsed version of block */
+	int index;	/* index in block */
+};
+
+/* Lump states */
+enum {
+	LumpFree,
+	LumpVenti,	/* on venti server: score > 2^32: just a cached copy */
+	LumpActive,	/* active */
+	LumpActiveRO,	/* active: read only block */
+	LumpActiveA,	/* active: achrived */
+	LumpSnap,	/* snapshot: */
+	LumpSnapRO,	/* snapshot: read only */
+	LumpSnapA,	/* snapshot: achived */
+	LumpZombie,	/* block with no pointer to it: waiting to be freed */
+	
+	LumpMax
+};
+
+/*
+ * Each lump has a state and generation
+ * The following invariants are maintained
+ * 	Each lump has no more than than one parent per generation
+ * 	For Active*, no child has a parent of a greater generation
+ *	For Snap*, there is a snap parent of given generation and there are
+ *		no parents of greater gen - implies no children of a greater gen
+ *	For *RO, the lump is fixed - no change ca be made - all pointers
+ *		are valid venti addresses
+ *	For *A, the lump is on the venti server
+ *	There are no pointers to Zombie lumps
+ *
+ * Transitions
+ *	Archiver at generation g
+ *	Mutator at generation h
+ *	
+ *	Want to modify a lump
+ *		Venti: create new Active(h)
+ *		Active(x): x == h: do nothing
+ *		Acitve(x): x < h: change to Snap(h-1) + add Active(h)
+ *		ActiveRO(x): change to SnapRO(h-1) + add Active(h)
+ *		ActiveA(x): add Active(h)
+ *		Snap*(x): should not occur
+ *		Zombie(x): should not occur
+ *	Want to archive
+ *		Active(x): x != g: should never happen
+ *		Active(x): x == g fix children and free them: move to ActoveRO(g);
+ *		ActiveRO(x): x != g: should never happen
+ *		ActiveRO(x): x == g: wait until it hits ActiveA or SnapA
+ *		ActiveA(x): done
+ *		Active(x): x < g: should never happen
+ *		Snap(x): x >= g: fix children, freeing all SnapA(y) x == y;
+ *		SnapRO(x): wait until it hits SnapA
+ *
+ */
+
+
+struct Lump {
+	int ref;
+
+	Cache *c;
+
+	VtLock *lk;
+	
+	int state;
+	ulong gen;
+
+	uchar 	*data;
+	uchar	score[VtScoreSize];	/* score of packet */
+	uchar	vscore[VtScoreSize];	/* venti score - when archived */
+	u8int	type;			/* type of packet */
+	int	dir;			/* part of a directory - extension of type */
+	u16int	asize;			/* allocated size of block */
+	Lump	*next;			/* doubly linked hash chains */
+	Lump	*prev;
+	u32int	heap;			/* index in heap table */
+	u32int	used;			/* last reference times */
+	u32int	used2;
+
+	u32int	addr;			/* mutable block address */
+};
+
diff --git a/src/cmd/vac/error.c b/src/cmd/vac/error.c
new file mode 100644
index 0000000..5c8ff29
--- /dev/null
+++ b/src/cmd/vac/error.c
@@ -0,0 +1,20 @@
+#include "stdinc.h"
+#include "vac.h"
+#include "dat.h"
+#include "fns.h"
+#include "error.h"
+
+char ENoDir[] = "directory entry is not allocated";
+char EBadDir[] = "corrupted directory entry";
+char EBadMeta[] = "corrupted meta data";
+char ENotDir[] = "not a directory";
+char ENotFile[] = "not a file";
+char EIO[] = "i/o error";
+char EBadOffset[] = "illegal offset";
+char ETooBig[] = "file too big";
+char EReadOnly[] = "read only";
+char ERemoved[] = "file has been removed";
+char ENilBlock[] = "illegal block address";
+char ENotEmpty[] = "directory not empty";
+char EExists[] = "file already exists";
+char ERoot[] = "cannot remove root";
diff --git a/src/cmd/vac/error.h b/src/cmd/vac/error.h
new file mode 100644
index 0000000..742228c
--- /dev/null
+++ b/src/cmd/vac/error.h
@@ -0,0 +1,14 @@
+extern char ENoDir[];
+extern char EBadDir[];
+extern char EBadMeta[];
+extern char ENilBlock[];
+extern char ENotDir[];
+extern char ENotFile[];
+extern char EIO[];
+extern char EBadOffset[];
+extern char ETooBig[];
+extern char EReadOnly[];
+extern char ERemoved[];
+extern char ENotEmpty[];
+extern char EExists[];
+extern char ERoot[];
diff --git a/src/cmd/vac/file.c b/src/cmd/vac/file.c
new file mode 100644
index 0000000..900422d
--- /dev/null
+++ b/src/cmd/vac/file.c
@@ -0,0 +1,1214 @@
+#include "stdinc.h"
+#include "vac.h"
+#include "dat.h"
+#include "fns.h"
+#include "error.h"
+
+/*
+ * locking order is upwards.  A thread can hold the lock for a VacFile
+ * and then acquire the lock of its parent
+ */
+
+struct VacFile {
+	/* meta data for file: protected by the lk in the parent */
+	int ref;		/* holds this data structure up */
+	VacFS *fs;		/* immutable */
+
+	int	removed;	/* file has been removed */
+	int	dirty;		/* dir is dirty with respect to meta data in block */
+	ulong	block;		/* block offset withing msource for this file's meta data */
+
+	VacDir dir;		/* meta data for this file */
+
+	VacFile *up;	/* parent file */
+	VacFile *next;	/* sibling */
+
+	/* data for file */
+	VtLock *lk;		/* lock for source and msource */
+	Source *source;
+	Source *msource;	/* for directories: meta data for children */
+	VacFile *down;		/* children */
+};
+
+static int vfMetaFlush(VacFile*);
+static ulong msAlloc(Source *ms, ulong, int n);
+
+static void
+vfRUnlock(VacFile *vf)
+{
+	vtRUnlock(vf->lk);
+}
+	
+
+static int
+vfRLock(VacFile *vf)
+{
+	vtRLock(vf->lk);
+	if(vf->source == nil) {
+		vfRUnlock(vf);
+		vtSetError(ERemoved);
+		return 0;
+	}
+	return 1;
+}
+
+static void
+vfUnlock(VacFile *vf)
+{
+	vtUnlock(vf->lk);
+}
+
+static int
+vfLock(VacFile *vf)
+{
+	vtLock(vf->lk);
+	if(vf->source == nil) {
+		vfUnlock(vf);
+		vtSetError(ERemoved);
+		return 0;
+	}
+	return 1;
+}
+
+static void
+vfMetaLock(VacFile *vf)
+{
+	assert(vf->up->msource != nil);
+	vtLock(vf->up->lk);
+}
+
+static void
+vfMetaUnlock(VacFile *vf)
+{
+	vtUnlock(vf->up->lk);
+}
+
+
+static void
+vfRAccess(VacFile* vf)
+{
+	vfMetaLock(vf);
+	vf->dir.atime = time(0L);
+	vf->dirty = 1;
+	vfMetaUnlock(vf);
+	vfMetaFlush(vf);
+}
+
+static void
+vfWAccess(VacFile* vf, char *mid)
+{
+	vfMetaLock(vf);
+	vf->dir.atime = vf->dir.mtime = time(0L);
+	if(strcmp(vf->dir.mid, mid) != 0) {
+		vtMemFree(vf->dir.mid);
+		vf->dir.mid = vtStrDup(mid);
+	}
+	vf->dir.mcount++;
+	vf->dirty = 1;
+	vfMetaUnlock(vf);
+	vfMetaFlush(vf);
+}
+
+void
+vdCleanup(VacDir *dir)
+{
+	vtMemFree(dir->elem);
+	dir->elem = nil;
+	vtMemFree(dir->uid);
+	dir->uid = nil;
+	vtMemFree(dir->gid);
+	dir->gid = nil;
+	vtMemFree(dir->mid);
+	dir->mid = nil;
+}
+
+void
+vdCopy(VacDir *dst, VacDir *src)
+{
+	*dst = *src;
+	dst->elem = vtStrDup(src->elem);
+	dst->uid = vtStrDup(src->uid);
+	dst->gid = vtStrDup(src->gid);
+	dst->mid = vtStrDup(src->mid);
+}
+
+static int
+mbSearch(MetaBlock *mb, char *elem, int *ri, MetaEntry *me)
+{
+	int i;
+	int b, t, x;
+
+	/* binary search within block */
+	b = 0;
+	t = mb->nindex;
+	while(b < t) {
+		i = (b+t)>>1;
+		if(!meUnpack(me, mb, i))
+			return 0;
+		if(mb->unbotch)
+			x = meCmpNew(me, elem);
+		else
+			x = meCmp(me, elem);
+
+		if(x == 0) {
+			*ri = i;
+			return 1;
+		}
+	
+		if(x < 0)
+			b = i+1;
+		else /* x > 0 */
+			t = i;
+	}
+
+	assert(b == t);
+	
+	*ri = b;	/* b is the index to insert this entry */
+	memset(me, 0, sizeof(*me));
+
+	return 1;
+}
+
+static void
+mbInit(MetaBlock *mb, uchar *p, int n)
+{
+	memset(mb, 0, sizeof(MetaBlock));
+	mb->maxsize = n;
+	mb->buf = p;
+	mb->maxindex = n/100;
+	mb->size = MetaHeaderSize + mb->maxindex*MetaIndexSize;
+}
+
+static int
+vfMetaFlush(VacFile *vf)
+{
+	VacFile *vfp;
+	Lump *u;
+	MetaBlock mb;
+	MetaEntry me, nme;
+	uchar *p;
+	int i, n, moved;
+
+//print("vfMetaFlush %s\n", vf->dir.elem);
+
+	/* assume name has not changed for the moment */
+
+	vfMetaLock(vf);
+
+	vfp = vf->up;
+	moved = 0;
+
+	u = sourceGetLump(vfp->msource, vf->block, 0, 1);
+	if(u == nil)
+		goto Err;
+
+	if(!mbUnpack(&mb, u->data, u->asize))
+		goto Err;
+	if(!mbSearch(&mb, vf->dir.elem, &i, &me) || me.p == nil)
+		goto Err;
+
+	nme = me;
+	n = vdSize(&vf->dir);
+//print("old size %d new size %d\n", me.size, n);
+	if(n <= nme.size) {
+		nme.size = n;
+	} else {
+		/* try expand entry? */
+		p = mbAlloc(&mb, n);
+//print("alloced %ld\n", p - mb.buf);
+		if(p == nil) {
+assert(0);
+			/* much more work */
+		}
+		nme.p = p;
+		nme.size = n;
+	}
+
+	mbDelete(&mb, i, &me);
+	memset(me.p, 0, me.size);
+	if(!moved) {
+		vdPack(&vf->dir, &nme);
+		mbInsert(&mb, i, &nme);
+	}
+
+	mbPack(&mb);
+	lumpDecRef(u, 1);
+
+	vf->dirty = 0;
+
+	vfMetaUnlock(vf);
+	return 1;
+
+Err:
+	lumpDecRef(u, 1);
+	vfMetaUnlock(vf);
+	return 0;
+}
+
+static VacFile *
+vfAlloc(VacFS *fs)
+{
+	VacFile *vf;
+
+	vf = vtMemAllocZ(sizeof(VacFile));
+	vf->lk = vtLockAlloc();
+	vf->ref = 1;
+	vf->fs = fs;
+	return vf;
+}
+
+static void
+vfFree(VacFile *vf)
+{
+	sourceFree(vf->source);
+	vtLockFree(vf->lk);	
+	sourceFree(vf->msource);
+	vdCleanup(&vf->dir);
+	
+	vtMemFree(vf);
+}
+
+/* the file is locked already */
+static VacFile *
+dirLookup(VacFile *vf, char *elem)
+{
+	int i, j, nb;
+	MetaBlock mb;
+	MetaEntry me;
+	Lump *u;
+	Source *meta;
+	VacFile *nvf;
+
+	meta = vf->msource;
+	u = nil;
+	nb = sourceGetNumBlocks(meta);
+	for(i=0; i<nb; i++) {
+		u = sourceGetLump(meta, i, 1, 1);
+		if(u == nil)
+			goto Err;
+		if(!mbUnpack(&mb, u->data, u->asize))
+			goto Err;
+		if(!mbSearch(&mb, elem, &j, &me))
+			goto Err;
+		if(me.p != nil) {
+			nvf = vfAlloc(vf->fs);
+			if(!vdUnpack(&nvf->dir, &me)) {
+				vfFree(nvf);
+				goto Err;
+			}
+			lumpDecRef(u, 1);
+			nvf->block = i;
+			return nvf;
+		}
+		
+		lumpDecRef(u, 1);
+		u = nil;
+	}
+	vtSetError("file does not exist");
+	/* fall through */
+Err:
+	lumpDecRef(u, 1);
+	return nil;
+}
+
+VacFile *
+vfRoot(VacFS *fs, uchar *score)
+{
+	VtEntry e;
+	Lump *u, *v;
+	Source *r, *r0, *r1, *r2;
+	MetaBlock mb;
+	MetaEntry me;
+	VacFile *root, *mr;
+
+	root = nil;
+	mr = nil;
+	r0 = nil;
+	r1 = nil;
+	r2 = nil;
+	v = nil;
+	r = nil;
+
+	u = cacheGetLump(fs->cache, score, VtDirType, fs->bsize);
+	if(u == nil)
+		goto Err;
+	if(!fs->readOnly) {
+		v = cacheAllocLump(fs->cache, VtDirType, fs->bsize, 1);
+		if(v == nil) {
+			vtUnlock(u->lk);
+			goto Err;
+		}
+		v->gen = u->gen;
+		v->asize = u->asize;
+		v->state = LumpActive;
+		memmove(v->data, u->data, v->asize);
+		lumpDecRef(u, 1);
+		u = v;
+		v = nil;
+	}
+	vtUnlock(u->lk);
+	vtEntryUnpack(&e, u->data, 2);
+	if(e.flags == 0){		/* just one entry */
+		r = sourceAlloc(fs->cache, u, 0, 0, fs->readOnly);
+		if(r == nil)
+			goto Err;
+		r0 = sourceOpen(r, 0, fs->readOnly);
+		if(r0 == nil)
+			goto Err;
+		r1 = sourceOpen(r, 1, fs->readOnly);
+		if(r1 == nil)
+			goto Err;
+		r2 = sourceOpen(r, 2, fs->readOnly);
+		if(r2 == nil)
+			goto Err;
+		sourceFree(r);
+		r = nil;
+	}else{
+		r0 = sourceAlloc(fs->cache, u, 0, 0, fs->readOnly);
+		if(r0 == nil)
+			goto Err;
+		r1 = sourceAlloc(fs->cache, u, 0, 1, fs->readOnly);
+		if(r1 == nil)
+			goto Err;
+		r2 = sourceAlloc(fs->cache, u, 0, 2, fs->readOnly);
+		if(r2 == nil)
+			goto Err;
+	}
+	lumpDecRef(u, 0);
+	u = sourceGetLump(r2, 0, 1, 0);
+	if(u == nil)
+		goto Err;
+
+	mr = vfAlloc(fs);
+	mr->msource = r2;
+	r2 = nil;
+
+	root = vfAlloc(fs);
+	root->up = mr;
+	root->source = r0;
+	r0 = nil;
+	root->msource = r1;
+	r1 = nil;
+
+	mr->down = root;
+
+	if(!mbUnpack(&mb, u->data, u->asize))
+		goto Err;
+
+	if(!meUnpack(&me, &mb, 0))
+		goto Err;
+	if(!vdUnpack(&root->dir, &me))
+		goto Err;
+
+	vfRAccess(root);
+	lumpDecRef(u, 0);
+	sourceFree(r2);
+
+	return root;
+Err:
+	lumpDecRef(u, 0);
+	lumpDecRef(v, 0);
+	if(r0)
+		sourceFree(r0);
+	if(r1)
+		sourceFree(r1);
+	if(r2)
+		sourceFree(r2);
+	if(r)
+		sourceFree(r);
+	if(mr)
+		vfFree(mr);
+	if(root)
+		vfFree(root);
+
+	return nil;
+}
+
+VacFile *
+vfWalk(VacFile *vf, char *elem)
+{
+	VacFile *nvf;
+
+	vfRAccess(vf);
+
+	if(elem[0] == 0) {
+		vtSetError("illegal path element");
+		return nil;
+	}
+	if(!vfIsDir(vf)) {
+		vtSetError("not a directory");
+		return nil;
+	}
+
+	if(strcmp(elem, ".") == 0) {
+		return vfIncRef(vf);
+	}
+
+	if(strcmp(elem, "..") == 0) {
+		if(vfIsRoot(vf))
+			return vfIncRef(vf);
+		return vfIncRef(vf->up);
+	}
+
+	if(!vfLock(vf))
+		return nil;
+
+	for(nvf = vf->down; nvf; nvf=nvf->next) {
+		if(strcmp(elem, nvf->dir.elem) == 0 && !nvf->removed) {
+			nvf->ref++;
+			goto Exit;
+		}
+	}
+
+	nvf = dirLookup(vf, elem);
+	if(nvf == nil)
+		goto Err;
+	nvf->source = sourceOpen(vf->source, nvf->dir.entry, vf->fs->readOnly);
+	if(nvf->source == nil)
+		goto Err;
+	if(nvf->dir.mode & ModeDir) {
+		nvf->msource = sourceOpen(vf->source, nvf->dir.mentry, vf->fs->readOnly);
+		if(nvf->msource == nil)
+			goto Err;
+	}
+
+	/* link in and up parent ref count */
+	nvf->next = vf->down;
+	vf->down = nvf;
+	nvf->up = vf;
+	vfIncRef(vf);
+Exit:
+	vfUnlock(vf);
+	return nvf;
+Err:
+	vfUnlock(vf);
+	if(nvf != nil)
+		vfFree(nvf);
+	return nil;
+}
+
+VacFile *
+vfOpen(VacFS *fs, char *path)
+{
+	VacFile *vf, *nvf;
+	char *p, elem[VtMaxStringSize];
+	int n;
+
+	vf = fs->root;
+	vfIncRef(vf);
+	while(*path != 0) {
+		for(p = path; *p && *p != '/'; p++)
+			;
+		n = p - path;
+		if(n > 0) {
+			if(n > VtMaxStringSize) {
+				vtSetError("path element too long");
+				goto Err;
+			}
+			memmove(elem, path, n);
+			elem[n] = 0;
+			nvf = vfWalk(vf, elem);
+			if(nvf == nil)
+				goto Err;
+			vfDecRef(vf);
+			vf = nvf;
+		}
+		if(*p == '/')
+			p++;
+		path = p;
+	}
+	return vf;
+Err:
+	vfDecRef(vf);
+	return nil;
+}
+
+VacFile *
+vfCreate(VacFile *vf, char *elem, ulong mode, char *user)
+{
+	VacFile *nvf;
+	VacDir *dir;
+	int n, i;
+	uchar *p;
+	Source *pr, *r, *mr;
+	int isdir;
+	MetaBlock mb;
+	MetaEntry me;
+	Lump *u;
+
+	if(!vfLock(vf))
+		return nil;
+
+	r = nil;
+	mr = nil;
+	u = nil;
+
+	for(nvf = vf->down; nvf; nvf=nvf->next) {
+		if(strcmp(elem, nvf->dir.elem) == 0 && !nvf->removed) {
+			nvf = nil;
+			vtSetError(EExists);
+			goto Err;
+		}
+	}
+
+	nvf = dirLookup(vf, elem);
+	if(nvf != nil) {
+		vtSetError(EExists);
+		goto Err;
+	}
+
+	nvf = vfAlloc(vf->fs);
+	isdir = mode & ModeDir;
+
+	pr = vf->source;
+	r = sourceCreate(pr, pr->psize, pr->dsize, isdir, 0);
+	if(r == nil)
+		goto Err;
+	if(isdir) {
+		mr = sourceCreate(pr, pr->psize, pr->dsize, 0, r->block*pr->epb + r->entry);
+		if(mr == nil)
+			goto Err;
+	}
+	
+	dir = &nvf->dir;
+	dir->elem = vtStrDup(elem);
+	dir->entry = r->block*pr->epb + r->entry;
+	dir->gen = r->gen;
+	if(isdir) {
+		dir->mentry = mr->block*pr->epb + mr->entry;
+		dir->mgen = mr->gen;
+	}
+	dir->size = 0;
+	dir->qid = vf->fs->qid++;
+	dir->uid = vtStrDup(user);
+	dir->gid = vtStrDup(vf->dir.gid);
+	dir->mid = vtStrDup(user);
+	dir->mtime = time(0L);
+	dir->mcount = 0;
+	dir->ctime = dir->mtime;
+	dir->atime = dir->mtime;
+	dir->mode = mode;
+
+	n = vdSize(dir);
+	nvf->block = msAlloc(vf->msource, 0, n);
+	if(nvf->block == NilBlock)
+		goto Err;
+	u = sourceGetLump(vf->msource, nvf->block, 0, 1);
+	if(u == nil)
+		goto Err;
+	if(!mbUnpack(&mb, u->data, u->asize))
+		goto Err;
+	p = mbAlloc(&mb, n);
+	if(p == nil)
+		goto Err;
+		
+	if(!mbSearch(&mb, elem, &i, &me))
+		goto Err;
+	assert(me.p == nil);
+	me.p = p;
+	me.size = n;
+
+	vdPack(dir, &me);
+	mbInsert(&mb, i, &me);
+	mbPack(&mb);
+	lumpDecRef(u, 1);
+
+	nvf->source = r;
+	nvf->msource = mr;
+
+	/* link in and up parent ref count */
+	nvf->next = vf->down;
+	vf->down = nvf;
+	nvf->up = vf;
+	vfIncRef(vf);
+
+	vfWAccess(vf, user);
+
+	vfUnlock(vf);
+	return nvf;
+
+Err:
+	lumpDecRef(u, 1);
+	if(r)
+		sourceRemove(r);
+	if(mr)
+		sourceRemove(mr);
+	if(nvf)
+		vfFree(nvf);
+	vfUnlock(vf);
+	return 0;
+}
+
+
+int
+vfRead(VacFile *vf, void *buf, int cnt, vlong offset)
+{
+	Source *s;
+	uvlong size;
+	ulong bn;
+	int off, dsize, n, nn;
+	Lump *u;
+	uchar *b;
+
+if(0)fprint(2, "vfRead: %s %d, %lld\n", vf->dir.elem, cnt, offset);
+
+	if(!vfRLock(vf))
+		return -1;
+
+	s = vf->source;
+
+	dsize = s->dsize;
+	size = sourceGetSize(s);
+
+	if(offset < 0) {
+		vtSetError(EBadOffset);
+		goto Err;
+	}
+
+	vfRAccess(vf);
+
+	if(offset >= size)
+		offset = size;
+
+	if(cnt > size-offset)
+		cnt = size-offset;
+	bn = offset/dsize;
+	off = offset%dsize;
+	b = buf;
+	while(cnt > 0) {
+		u = sourceGetLump(s, bn, 1, 0);
+		if(u == nil)
+			goto Err;
+		if(u->asize <= off) {
+			lumpDecRef(u, 0);
+			goto Err;
+		}
+		n = cnt;
+		if(n > dsize-off)
+			n = dsize-off;
+		nn = u->asize-off;
+		if(nn > n)
+			nn = n;
+		memmove(b, u->data+off, nn);
+		memset(b+nn, 0, n-nn);
+		off = 0;
+		bn++;
+		cnt -= n;
+		b += n;
+		lumpDecRef(u, 0);
+	}
+	vfRUnlock(vf);
+	return b-(uchar*)buf;
+Err:
+	vfRUnlock(vf);
+	return -1;
+}
+
+int
+vfWrite(VacFile *vf, void *buf, int cnt, vlong offset, char *user)
+{
+	Source *s;
+	ulong bn;
+	int off, dsize, n;
+	Lump *u;
+	uchar *b;
+
+	USED(user);
+
+	if(!vfLock(vf))
+		return -1;
+
+	if(vf->fs->readOnly) {
+		vtSetError(EReadOnly);
+		goto Err;
+	}
+
+	if(vf->dir.mode & ModeDir) {
+		vtSetError(ENotFile);
+		goto Err;
+	}
+if(0)fprint(2, "vfWrite: %s %d, %lld\n", vf->dir.elem, cnt, offset);
+
+	s = vf->source;
+	dsize = s->dsize;
+
+	if(offset < 0) {
+		vtSetError(EBadOffset);
+		goto Err;
+	}
+
+	vfWAccess(vf, user);
+
+	bn = offset/dsize;
+	off = offset%dsize;
+	b = buf;
+	while(cnt > 0) {
+		n = cnt;
+		if(n > dsize-off)
+			n = dsize-off;
+		if(!sourceSetDepth(s, offset+n))
+			goto Err;
+		u = sourceGetLump(s, bn, 0, 0);
+		if(u == nil)
+			goto Err;
+		if(u->asize < dsize) {
+			vtSetError("runt block");
+			lumpDecRef(u, 0);
+			goto Err;
+		}
+		memmove(u->data+off, b, n);
+		off = 0;
+		cnt -= n;
+		b += n;
+		offset += n;
+		bn++;
+		lumpDecRef(u, 0);
+		if(!sourceSetSize(s, offset))
+			goto Err;
+	}
+	vfLock(vf);
+	return b-(uchar*)buf;
+Err:
+	vfLock(vf);
+	return -1;
+}
+
+int
+vfGetDir(VacFile *vf, VacDir *dir)
+{
+	if(!vfRLock(vf))
+		return 0;
+
+	vfMetaLock(vf);
+	vdCopy(dir, &vf->dir);
+	vfMetaUnlock(vf);
+
+	if(!vfIsDir(vf))
+		dir->size = sourceGetSize(vf->source);
+	vfRUnlock(vf);
+
+	return 1;
+}
+
+uvlong
+vfGetId(VacFile *vf)
+{
+	/* immutable */
+	return vf->dir.qid;
+}
+
+ulong
+vfGetMcount(VacFile *vf)
+{
+	ulong mcount;
+	
+	vfMetaLock(vf);
+	mcount = vf->dir.mcount;
+	vfMetaUnlock(vf);
+	return mcount;
+}
+
+
+int
+vfIsDir(VacFile *vf)
+{
+	/* immutable */
+	return (vf->dir.mode & ModeDir) != 0;
+}
+
+int
+vfIsRoot(VacFile *vf)
+{
+	return vf == vf->fs->root;
+}
+
+int
+vfGetSize(VacFile *vf, uvlong *size)
+{
+	if(!vfRLock(vf))
+		return 0;
+	*size = sourceGetSize(vf->source);
+	vfRUnlock(vf);
+
+	return 1;
+}
+
+static int
+vfMetaRemove(VacFile *vf, char *user)
+{
+	Lump *u;
+	MetaBlock mb;
+	MetaEntry me;
+	int i;
+	VacFile *vfp;
+
+	vfp = vf->up;
+
+	vfWAccess(vfp, user);
+
+	vfMetaLock(vf);
+
+	u = sourceGetLump(vfp->msource, vf->block, 0, 1);
+	if(u == nil)
+		goto Err;
+
+	if(!mbUnpack(&mb, u->data, u->asize))
+		goto Err;
+	if(!mbSearch(&mb, vf->dir.elem, &i, &me) || me.p == nil)
+		goto Err;
+print("deleting %d entry\n", i);
+	mbDelete(&mb, i, &me);
+	memset(me.p, 0, me.size);
+	mbPack(&mb);
+	
+	lumpDecRef(u, 1);
+	
+	vf->removed = 1;
+	vf->block = NilBlock;
+
+	vfMetaUnlock(vf);
+	return 1;
+
+Err:
+	lumpDecRef(u, 1);
+	vfMetaUnlock(vf);
+	return 0;
+}
+
+
+static int
+vfCheckEmpty(VacFile *vf)
+{
+	int i, n;
+	Lump *u;
+	MetaBlock mb;
+	Source *r;
+
+	r = vf->msource;
+	n = sourceGetNumBlocks(r);
+	for(i=0; i<n; i++) {
+		u = sourceGetLump(r, i, 1, 1);
+		if(u == nil)
+			goto Err;
+		if(!mbUnpack(&mb, u->data, u->asize))
+			goto Err;
+		if(mb.nindex > 0) {
+			vtSetError(ENotEmpty);
+			goto Err;
+		}
+		lumpDecRef(u, 1);
+	}
+	return 1;
+Err:
+	lumpDecRef(u, 1);
+	return 0;
+}
+
+int
+vfRemove(VacFile *vf, char *user)
+{	
+	/* can not remove the root */
+	if(vfIsRoot(vf)) {
+		vtSetError(ERoot);
+		return 0;
+	}
+
+	if(!vfLock(vf))
+		return 0;
+
+	if(vfIsDir(vf) && !vfCheckEmpty(vf))
+		goto Err;
+			
+	assert(vf->down == nil);
+
+	sourceRemove(vf->source);
+	vf->source = nil;
+	if(vf->msource) {
+		sourceRemove(vf->msource);
+		vf->msource = nil;
+	}
+	
+	vfUnlock(vf);
+	
+	if(!vfMetaRemove(vf, user))
+		return 0;
+	
+	return 1;
+		
+Err:
+	vfUnlock(vf);
+	return 0;
+}
+
+VacFile *
+vfIncRef(VacFile *vf)
+{
+	vfMetaLock(vf);
+	assert(vf->ref > 0);
+	vf->ref++;
+	vfMetaUnlock(vf);
+	return vf;
+}
+
+void
+vfDecRef(VacFile *vf)
+{
+	VacFile *p, *q, **qq;
+
+	if(vf->up == nil) {
+		vfFree(vf);
+		return;
+	}
+
+	vfMetaLock(vf);
+	vf->ref--;
+	if(vf->ref > 0) {
+		vfMetaUnlock(vf);
+		return;
+	}
+	assert(vf->ref == 0);
+	assert(vf->down == nil);
+
+	p = vf->up;
+	qq = &p->down;
+	for(q = *qq; q; qq=&q->next,q=*qq)
+		if(q == vf)
+			break;
+	assert(q != nil);
+	*qq = vf->next;
+
+	vfMetaUnlock(vf);
+	vfFree(vf);
+
+	vfDecRef(p);
+}
+
+int
+vfGetVtEntry(VacFile *vf, VtEntry *e)
+{
+	int res;
+
+	if(!vfRLock(vf))
+		return 0;
+	res = sourceGetVtEntry(vf->source, e);
+	vfRUnlock(vf);
+	return res;
+}
+
+int
+vfGetBlockScore(VacFile *vf, ulong bn, uchar score[VtScoreSize])
+{
+	Lump *u;
+	int ret, off;
+	Source *r;
+
+	if(!vfRLock(vf))
+		return 0;
+
+	r = vf->source;
+
+	u = sourceWalk(r, bn, 1, &off);
+	if(u == nil){
+		vfRUnlock(vf);
+		return 0;
+	}
+
+	ret = lumpGetScore(u, off, score);
+	lumpDecRef(u, 0);
+	vfRUnlock(vf);
+
+	return ret;
+}
+
+VacFile *
+vfGetParent(VacFile *vf)
+{
+	if(vfIsRoot(vf))
+		return vfIncRef(vf);
+	return vfIncRef(vf->up);
+}
+
+static VacDirEnum *
+vdeAlloc(VacFile *vf)
+{
+	VacDirEnum *ds;
+
+	if(!(vf->dir.mode & ModeDir)) {
+		vtSetError(ENotDir);
+		vfDecRef(vf);
+		return nil;
+	}
+
+	ds = vtMemAllocZ(sizeof(VacDirEnum));
+	ds->file = vf;
+	
+	return ds;
+}
+
+VacDirEnum *
+vdeOpen(VacFS *fs, char *path)
+{
+	VacFile *vf;
+
+	vf = vfOpen(fs, path);
+	if(vf == nil)
+		return nil;
+
+	return vdeAlloc(vf);
+}
+
+VacDirEnum *
+vfDirEnum(VacFile *vf)
+{
+	return vdeAlloc(vfIncRef(vf));
+}
+
+static int
+dirEntrySize(Source *s, ulong elem, ulong gen, uvlong *size)
+{
+	Lump *u;
+	ulong bn;
+	VtEntry e;
+
+	bn = elem/s->epb;
+	elem -= bn*s->epb;
+
+	u = sourceGetLump(s, bn, 1, 1);
+	if(u == nil)
+		goto Err;
+	if(u->asize < (elem+1)*VtEntrySize) {
+		vtSetError(ENoDir);
+		goto Err;
+	}
+	vtEntryUnpack(&e, u->data, elem);
+	if(!(e.flags & VtEntryActive) || e.gen != gen) {
+fprint(2, "gen mismatch\n");
+		vtSetError(ENoDir);
+		goto Err;
+	}
+
+	*size = e.size;
+	lumpDecRef(u, 1);
+	return 1;	
+
+Err:
+	lumpDecRef(u, 1);
+	return 0;
+}
+
+int
+vdeRead(VacDirEnum *ds, VacDir *dir, int n)
+{
+	ulong nb;
+	int i;
+	Source *meta, *source;
+	MetaBlock mb;
+	MetaEntry me;
+	Lump *u;
+
+	vfRAccess(ds->file);
+
+	if(!vfRLock(ds->file))
+		return -1;
+
+	i = 0;
+	u = nil;
+	source = ds->file->source;
+	meta = ds->file->msource;
+	nb = (sourceGetSize(meta) + meta->dsize - 1)/meta->dsize;
+
+	if(ds->block >= nb)
+		goto Exit;
+	u = sourceGetLump(meta, ds->block, 1, 1);
+	if(u == nil)
+		goto Err;
+	if(!mbUnpack(&mb, u->data, u->asize))
+		goto Err;
+
+	for(i=0; i<n; i++) {
+		while(ds->index >= mb.nindex) {
+			lumpDecRef(u, 1);
+			u = nil;
+			ds->index = 0;
+			ds->block++;
+			if(ds->block >= nb)
+				goto Exit;
+			u = sourceGetLump(meta, ds->block, 1, 1);
+			if(u == nil)
+				goto Err;
+			if(!mbUnpack(&mb, u->data, u->asize))
+				goto Err;
+		}
+		if(!meUnpack(&me, &mb, ds->index))
+			goto Err;
+		if(dir != nil) {
+			if(!vdUnpack(&dir[i], &me))
+				goto Err;
+			if(!(dir[i].mode & ModeDir))
+			if(!dirEntrySize(source, dir[i].entry, dir[i].gen, &dir[i].size))
+				goto Err;
+		}
+		ds->index++;
+	}
+Exit:
+	lumpDecRef(u, 1);
+	vfRUnlock(ds->file);
+	return i;
+Err:
+	lumpDecRef(u, 1);
+	vfRUnlock(ds->file);
+	n = i;
+	for(i=0; i<n ; i++)
+		vdCleanup(&dir[i]);
+	return -1;
+}
+
+void
+vdeFree(VacDirEnum *ds)
+{
+	if(ds == nil)
+		return;
+	vfDecRef(ds->file);
+	vtMemFree(ds);
+}
+
+static ulong
+msAlloc(Source *ms, ulong start, int n)
+{
+	ulong nb, i;
+	Lump *u;
+	MetaBlock mb;
+
+	nb = sourceGetNumBlocks(ms);
+	u = nil;
+	if(start > nb)
+		start = nb;
+	for(i=start; i<nb; i++) {
+		u = sourceGetLump(ms, i, 1, 1);
+		if(u == nil)
+			goto Err;
+		if(!mbUnpack(&mb, u->data, ms->dsize))
+			goto Err;
+		if(mb.maxsize - mb.size + mb.free >= n && mb.nindex < mb.maxindex)
+			break;
+		lumpDecRef(u, 1);
+		u = nil;
+	}
+	/* add block to meta file */
+	if(i == nb) {
+		if(!sourceSetDepth(ms, (i+1)*ms->dsize))
+			goto Err;
+		u = sourceGetLump(ms, i, 0, 1);
+		if(u == nil)
+			goto Err;
+		sourceSetSize(ms, (nb+1)*ms->dsize);
+		mbInit(&mb, u->data, u->asize);
+		mbPack(&mb);
+	}
+	lumpDecRef(u, 1);
+	return i;
+Err:
+	lumpDecRef(u, 1);
+	return NilBlock;
+}
+
diff --git a/src/cmd/vac/fns.h b/src/cmd/vac/fns.h
new file mode 100644
index 0000000..f013f12
--- /dev/null
+++ b/src/cmd/vac/fns.h
@@ -0,0 +1,46 @@
+Source	*sourceAlloc(Cache*, Lump *u, ulong block, int elem, int readonly);
+Source 	*sourceOpen(Source*, ulong entry, int readOnly);
+Source 	*sourceCreate(Source*, int psize, int dsize, int isdir, ulong entry);
+Lump	*sourceGetLump(Source*, ulong block, int readOnly, int lock);
+Lump	*sourceWalk(Source *r, ulong block, int readOnly, int *);
+int	sourceSetDepth(Source *r, uvlong size);
+int	sourceSetSize(Source *r, uvlong size);
+uvlong	sourceGetSize(Source *r);
+int	sourceSetDirSize(Source *r, ulong size);
+ulong	sourceGetDirSize(Source *r);
+void	sourceRemove(Source*);
+void	sourceFree(Source*);
+int	sourceGetVtEntry(Source *r, VtEntry *dir);
+ulong	sourceGetNumBlocks(Source *r);
+
+Lump	*lumpWalk(Lump *u, int offset, int type, int size, int readOnly, int lock);
+int	lumpGetScore(Lump *u, int offset, uchar score[VtScoreSize]);
+void	lumpDecRef(Lump*, int unlock);
+Lump	*lumpIncRef(Lump*);
+void	lumpFreeEntry(Lump *u, int entry);
+
+Cache 	*cacheAlloc(VtSession *z, int blockSize, long nblocks);
+Lump 	*cacheAllocLump(Cache *c, int type, int size, int dir);
+void	cacheFree(Cache *c);
+long	cacheGetSize(Cache*);
+int	cacheSetSize(Cache*, long);
+int	cacheGetBlockSize(Cache *c);
+Lump 	*cacheGetLump(Cache *c, uchar score[VtScoreSize], int type, int size);
+void	cacheCheck(Cache*);
+
+int	mbUnpack(MetaBlock *mb, uchar *p, int n);
+void	mbInsert(MetaBlock *mb, int i, MetaEntry*);
+void	mbDelete(MetaBlock *mb, int i, MetaEntry*);
+void	mbPack(MetaBlock *mb);
+uchar	*mbAlloc(MetaBlock *mb, int n);
+
+int	meUnpack(MetaEntry*, MetaBlock *mb, int i);
+int	meCmp(MetaEntry*, char *s);
+int	meCmpNew(MetaEntry*, char *s);
+
+int	vdSize(VacDir *dir);
+int	vdUnpack(VacDir *dir, MetaEntry*);
+void	vdPack(VacDir *dir, MetaEntry*);
+
+VacFile *vfRoot(VacFS *fs, uchar *score);
+
diff --git a/src/cmd/vac/fs.c b/src/cmd/vac/fs.c
new file mode 100644
index 0000000..568e2ec
--- /dev/null
+++ b/src/cmd/vac/fs.c
@@ -0,0 +1,188 @@
+#include "stdinc.h"
+#include "vac.h"
+#include "dat.h"
+#include "fns.h"
+
+static char EBadVacFormat[] = "bad format for vac file";
+
+static VacFS *
+vfsAlloc(VtSession *z, int bsize, long ncache)
+{
+	VacFS *fs;
+
+	fs = vtMemAllocZ(sizeof(VacFS));
+	fs->ref = 1;
+	fs->z = z;
+	fs->bsize = bsize;
+	fs->cache = cacheAlloc(z, bsize, ncache);
+	return fs;
+}
+
+static int
+readScore(int fd, uchar score[VtScoreSize])
+{
+	char buf[44];
+	int i, n, c;
+
+	n = readn(fd, buf, sizeof(buf));
+	if(n < sizeof(buf)) {
+		vtSetError("short read");
+		return 0;
+	}
+	if(strncmp(buf, "vac:", 4) != 0) {
+		vtSetError("not a vac file");
+		return 0;
+	}
+	memset(score, 0, VtScoreSize);
+	for(i=4; i<sizeof(buf); i++) {
+		if(buf[i] >= '0' && buf[i] <= '9')
+			c = buf[i] - '0';
+		else if(buf[i] >= 'a' && buf[i] <= 'f')
+			c = buf[i] - 'a' + 10;
+		else if(buf[i] >= 'A' && buf[i] <= 'F')
+			c = buf[i] - 'A' + 10;
+		else {
+			vtSetError("bad format for venti score");
+			return 0;
+		}
+		if((i & 1) == 0)
+			c <<= 4;
+	
+		score[(i>>1)-2] |= c;
+	}
+	return 1;
+}
+
+VacFS *
+vfsOpen(VtSession *z, char *file, int readOnly, long ncache)
+{
+	VacFS *fs;
+	int n, fd;
+	VtRoot rt;
+	uchar score[VtScoreSize], buf[VtRootSize];
+	VacFile *root;
+
+	fd = open(file, OREAD);
+	if(fd < 0) {
+		vtOSError();
+		return nil;
+	}
+
+	if(!readScore(fd, score)) {
+		close(fd);
+		return nil;
+	}
+	close(fd);
+
+	n = vtRead(z, score, VtRootType, buf, VtRootSize);
+	if(n < 0)
+		return nil;
+	if(n != VtRootSize) {
+		vtSetError("vtRead on root too short");
+		return nil;
+	}
+
+	if(!vtSha1Check(score, buf, VtRootSize)) {
+		vtSetError("vtSha1Check failed on root block");	
+		return nil;
+	}
+
+	if(!vtRootUnpack(&rt, buf))
+		return nil;
+
+	if(strcmp(rt.type, "vac") != 0) {
+		vtSetError("not a vac root");
+		return nil;
+	}
+
+	fs = vfsAlloc(z, rt.blockSize, ncache);
+	memmove(fs->score, score, VtScoreSize);
+	fs->readOnly = readOnly;
+	root = vfRoot(fs, rt.score);
+	if(root == nil)
+		goto Err;
+	fs->root = root;
+
+	return fs;
+Err:
+	if(root)
+		vfDecRef(root);
+	vfsClose(fs);
+	return nil;
+}
+
+VacFS *
+vacFsCreate(VtSession *z, int bsize, long ncache)
+{
+	VacFS *fs;
+
+	fs = vfsAlloc(z, bsize, ncache);
+	return fs;
+}
+
+int
+vfsIsReadOnly(VacFS *fs)
+{
+	return fs->readOnly != 0;
+}
+
+VacFile *
+vfsGetRoot(VacFS *fs)
+{
+	return vfIncRef(fs->root);
+}
+
+int
+vfsGetBlockSize(VacFS *fs)
+{
+	return fs->bsize;
+}
+
+int
+vfsGetScore(VacFS *fs, uchar score[VtScoreSize])
+{
+	memmove(fs, score, VtScoreSize);
+	return 1;
+}
+
+long
+vfsGetCacheSize(VacFS *fs)
+{
+	return cacheGetSize(fs->cache);
+}
+
+int
+vfsSetCacheSize(VacFS *fs, long size)
+{
+	return cacheSetSize(fs->cache, size);
+}
+
+int
+vfsSnapshot(VacFS *fs, char *src, char *dst)
+{
+	USED(fs);
+	USED(src);
+	USED(dst);
+	return 1;
+}
+
+int
+vfsSync(VacFS*)
+{
+	return 1;
+}
+
+int
+vfsClose(VacFS *fs)
+{
+	if(fs->root)
+		vfDecRef(fs->root);
+	fs->root = nil;
+	cacheCheck(fs->cache);
+	cacheFree(fs->cache);
+	memset(fs, 0, sizeof(VacFS));
+	vtMemFree(fs);
+	return 1;
+}
+
+
diff --git a/src/cmd/vac/mkfile b/src/cmd/vac/mkfile
new file mode 100644
index 0000000..ac33ab3
--- /dev/null
+++ b/src/cmd/vac/mkfile
@@ -0,0 +1,36 @@
+PLAN9=../../..
+<$PLAN9/src/mkhdr
+
+LIBFILES=\
+	cache\
+	error\
+	file\
+	fs\
+	source\
+	pack\
+
+LIB=${LIBFILES:%=%.$O}
+
+HFILES=\
+	$PLAN9/include/venti.h\
+	stdinc.h\
+	error.h\
+	vac.h\
+	dat.h\
+	fns.h\
+
+TARG=vac vtdump
+
+CFILES=${TARG:%=%.c} ${LIBFILES:%=%.c} srcload.c vactest.c
+
+UPDATE=\
+	mkfile\
+	$CFILES\
+	$HFILES\
+	${TARG:%=/386/bin/%}
+
+default:V: all
+
+test:V: $O.srcload $O.wtest $O.rtest $O.vtdump $O.vtread
+
+<$PLAN9/src/mkmany
diff --git a/src/cmd/vac/pack.c b/src/cmd/vac/pack.c
new file mode 100644
index 0000000..b16834d
--- /dev/null
+++ b/src/cmd/vac/pack.c
@@ -0,0 +1,609 @@
+#include "stdinc.h"
+#include "vac.h"
+#include "dat.h"
+#include "fns.h"
+#include "error.h"
+
+typedef struct MetaChunk MetaChunk;
+
+struct MetaChunk {
+	ushort offset;
+	ushort size;
+	ushort index;
+};
+
+static int	stringUnpack(char **s, uchar **p, int *n);
+
+/*
+ * integer conversion routines
+ */
+#define	U8GET(p)	((p)[0])
+#define	U16GET(p)	(((p)[0]<<8)|(p)[1])
+#define	U32GET(p)	(((p)[0]<<24)|((p)[1]<<16)|((p)[2]<<8)|(p)[3])
+#define	U48GET(p)	(((uvlong)U16GET(p)<<32)|(uvlong)U32GET((p)+2))
+#define	U64GET(p)	(((uvlong)U32GET(p)<<32)|(uvlong)U32GET((p)+4))
+
+#define	U8PUT(p,v)	(p)[0]=(v)
+#define	U16PUT(p,v)	(p)[0]=(v)>>8;(p)[1]=(v)
+#define	U32PUT(p,v)	(p)[0]=(v)>>24;(p)[1]=(v)>>16;(p)[2]=(v)>>8;(p)[3]=(v)
+#define	U48PUT(p,v,t32)	t32=(v)>>32;U16PUT(p,t32);t32=(v);U32PUT((p)+2,t32)
+#define	U64PUT(p,v,t32)	t32=(v)>>32;U32PUT(p,t32);t32=(v);U32PUT((p)+4,t32)
+
+static int
+stringUnpack(char **s, uchar **p, int *n)
+{
+	int nn;
+
+	if(*n < 2)
+		return 0;
+	
+	nn = U16GET(*p);
+	*p += 2;
+	*n -= 2;
+	if(nn > *n)
+		return 0;
+	*s = vtMemAlloc(nn+1);
+	memmove(*s, *p, nn);
+	(*s)[nn] = 0;
+	*p += nn;
+	*n -= nn;
+	return 1;
+}
+
+static int
+stringPack(char *s, uchar *p)
+{
+	int n;
+
+	n = strlen(s);
+	U16PUT(p, n);
+	memmove(p+2, s, n);
+	return n+2;
+}
+
+
+int
+mbUnpack(MetaBlock *mb, uchar *p, int n)
+{
+	u32int magic;
+
+	mb->maxsize = n;
+	mb->buf = p;
+
+	if(n == 0) {
+		memset(mb, 0, sizeof(MetaBlock));
+		return 1;
+	}
+
+	magic = U32GET(p);
+	if(magic != MetaMagic && magic != MetaMagic+1) {
+		vtSetError("bad meta block magic");
+		return 0;
+	}
+	mb->size = U16GET(p+4);
+	mb->free = U16GET(p+6);
+	mb->maxindex = U16GET(p+8);
+	mb->nindex = U16GET(p+10);
+	mb->unbotch = (magic == MetaMagic+1);
+
+	if(mb->size > n) {
+		vtSetError("bad meta block size");
+		return 0;
+	}
+	p += MetaHeaderSize;
+	n -= MetaHeaderSize;
+
+	USED(p);
+	if(n < mb->maxindex*MetaIndexSize) {
+ 		vtSetError("truncated meta block 2");
+		return 0;
+	}
+	return 1;
+}
+
+void
+mbPack(MetaBlock *mb)
+{
+	uchar *p;
+
+	p = mb->buf;
+
+	U32PUT(p, MetaMagic);
+	U16PUT(p+4, mb->size);
+	U16PUT(p+6, mb->free);
+	U16PUT(p+8, mb->maxindex);
+	U16PUT(p+10, mb->nindex);
+}
+
+
+void
+mbDelete(MetaBlock *mb, int i, MetaEntry *me)
+{
+	uchar *p;
+	int n;
+
+	assert(i < mb->nindex);
+
+	if(me->p - mb->buf + me->size == mb->size)
+		mb->size -= me->size;
+	else
+		mb->free += me->size;
+
+	p = mb->buf + MetaHeaderSize + i*MetaIndexSize;
+	n = (mb->nindex-i-1)*MetaIndexSize;
+	memmove(p, p+MetaIndexSize, n);
+	memset(p+n, 0, MetaIndexSize);
+	mb->nindex--;
+}
+
+void
+mbInsert(MetaBlock *mb, int i, MetaEntry *me)
+{
+	uchar *p;
+	int o, n;
+
+	assert(mb->nindex < mb->maxindex);
+
+	o = me->p - mb->buf;
+	n = me->size;
+	if(o+n > mb->size) {
+		mb->free -= mb->size - o;
+		mb->size = o + n;
+	} else
+		mb->free -= n;
+
+	p = mb->buf + MetaHeaderSize + i*MetaIndexSize;
+	n = (mb->nindex-i)*MetaIndexSize;
+	memmove(p+MetaIndexSize, p, n);
+	U16PUT(p, me->p - mb->buf);
+	U16PUT(p+2, me->size);
+	mb->nindex++;
+}
+
+int
+meUnpack(MetaEntry *me, MetaBlock *mb, int i)
+{
+	uchar *p;
+	int eo, en;
+
+	if(i < 0 || i >= mb->nindex) {
+		vtSetError("bad meta entry index");
+		return 0;
+	}
+
+	p = mb->buf + MetaHeaderSize + i*MetaIndexSize;
+	eo = U16GET(p);
+	en = U16GET(p+2);
+
+if(0)print("eo = %d en = %d\n", eo, en);
+	if(eo < MetaHeaderSize + mb->maxindex*MetaIndexSize) {
+		vtSetError("corrupted entry in meta block");
+		return 0;
+	}
+
+	if(eo+en > mb->size) {
+ 		vtSetError("truncated meta block");
+		return 0;
+	}
+
+	p = mb->buf + eo;
+	
+	/* make sure entry looks ok and includes an elem name */
+	if(en < 8 || U32GET(p) != DirMagic || en < 8 + U16GET(p+6)) {
+		vtSetError("corrupted meta block entry");
+		return 0;
+	}
+
+	me->p = p;
+	me->size = en;
+
+	return 1;
+}
+
+/* assumes a small amount of checking has been done in mbEntry */
+int
+meCmp(MetaEntry *me, char *s)
+{
+	int n;
+	uchar *p;
+
+	p = me->p;
+
+	p += 6;
+	n = U16GET(p);
+	p += 2;
+
+	assert(n + 8 < me->size);
+
+	while(n > 0) {
+		if(*s == 0)
+			return -1;
+		if(*p < (uchar)*s)
+			return -1;
+		if(*p > (uchar)*s)
+			return 1;
+		p++;
+		s++;
+		n--;
+	}
+	return *s != 0;
+}
+
+int
+meCmpNew(MetaEntry *me, char *s)
+{
+	int n;
+	uchar *p;
+
+	p = me->p;
+
+	p += 6;
+	n = U16GET(p);
+	p += 2;
+
+	assert(n + 8 < me->size);
+
+	while(n > 0) {
+		if(*s == 0)
+			return 1;
+		if(*p < (uchar)*s)
+			return -1;
+		if(*p > (uchar)*s)
+			return 1;
+		p++;
+		s++;
+		n--;
+	}
+	return -(*s != 0);
+}
+
+static int
+offsetCmp(void *s0, void *s1)
+{
+	MetaChunk *mc0, *mc1;
+
+	mc0 = s0;
+	mc1 = s1;
+	if(mc0->offset < mc1->offset)
+		return -1;
+	if(mc0->offset > mc1->offset)
+		return 1;
+	return 0;
+}
+
+static MetaChunk *
+metaChunks(MetaBlock *mb)
+{
+	MetaChunk *mc;
+	int oo, o, n, i;
+	uchar *p;
+
+	mc = vtMemAlloc(mb->nindex*sizeof(MetaChunk));
+	p = mb->buf + MetaHeaderSize;
+	for(i = 0; i<mb->nindex; i++) {
+		mc[i].offset = U16GET(p);
+		mc[i].size = U16GET(p+2);
+		mc[i].index = i;
+		p += MetaIndexSize;
+	}
+
+	qsort(mc, mb->nindex, sizeof(MetaChunk), offsetCmp);
+
+	/* check block looks ok */
+	oo = MetaHeaderSize + mb->maxindex*MetaIndexSize;
+	o = oo;
+	n = 0;
+	for(i=0; i<mb->nindex; i++) {
+		o = mc[i].offset;
+		n = mc[i].size;
+		if(o < oo)
+			goto Err;
+		oo += n;
+	}
+	if(o+n <= mb->size)
+		goto Err;
+	if(mb->size - oo != mb->free)
+		goto Err;
+
+	return mc;
+Err:
+	vtMemFree(mc);
+	return nil;
+}
+
+static void
+mbCompact(MetaBlock *mb, MetaChunk *mc)
+{
+	int oo, o, n, i;
+
+	oo = MetaHeaderSize + mb->maxindex*MetaIndexSize;
+	
+	for(i=0; i<mb->nindex; i++) {
+		o = mc[i].offset;
+		n = mc[i].size;
+		if(o != oo) {
+			memmove(mb->buf + oo, mb->buf + o, n);
+			U16PUT(mb->buf + MetaHeaderSize + mc[i].index*MetaIndexSize, oo);
+		}
+		oo += n;
+	}
+
+	mb->size = oo;
+	mb->free = 0;
+}
+
+uchar *
+mbAlloc(MetaBlock *mb, int n)
+{
+	int i, o;
+	MetaChunk *mc;
+
+	/* off the end */
+	if(mb->maxsize - mb->size >= n)
+		return mb->buf + mb->size;
+
+	/* check if possible */
+	if(mb->maxsize - mb->size + mb->free < n)
+		return nil;
+
+	mc = metaChunks(mb);
+
+	/* look for hole */
+	o = MetaHeaderSize + mb->maxindex*MetaIndexSize;
+	for(i=0; i<mb->nindex; i++) {
+		if(mc[i].offset - o >= n) {
+			vtMemFree(mc);
+			return mb->buf + o;
+		}
+		o = mc[i].offset + mc[i].size;
+	}
+
+	if(mb->maxsize - o >= n) {
+		vtMemFree(mc);
+		return mb->buf + o;
+	}
+
+	/* compact and return off the end */
+	mbCompact(mb, mc);
+	vtMemFree(mc);
+
+	assert(mb->maxsize - mb->size >= n);
+	return mb->buf + mb->size;
+}
+
+int
+vdSize(VacDir *dir)
+{
+	int n;
+	
+	/* constant part */
+
+	n = 	4 +	/* magic */
+		2 + 	/* version */
+		4 +	/* entry */
+		4 + 	/* guid */
+		4 + 	/* mentry */
+		4 + 	/* mgen */
+		8 +	/* qid */
+		4 + 	/* mtime */
+		4 + 	/* mcount */
+		4 + 	/* ctime */
+		4 + 	/* atime */
+		4 +	/* mode */
+		0;
+
+	/* strings */
+	n += 2 + strlen(dir->elem);
+	n += 2 + strlen(dir->uid);
+	n += 2 + strlen(dir->gid);
+	n += 2 + strlen(dir->mid);
+
+	/* optional sections */
+	if(dir->qidSpace) {
+		n += 	3 + 	/* option header */
+			8 + 	/* qidOffset */
+			8;	/* qid Max */
+	}
+
+	return n;
+}
+
+void
+vdPack(VacDir *dir, MetaEntry *me)
+{
+	uchar *p;
+	ulong t32;
+
+	p = me->p;
+	
+	U32PUT(p, DirMagic);
+	U16PUT(p+4, 9);		/* version */
+	p += 6;
+
+	p += stringPack(dir->elem, p);
+
+	U32PUT(p, dir->entry);
+	U32PUT(p+4, dir->gen);
+	U32PUT(p+8, dir->mentry);
+	U32PUT(p+12, dir->mgen);
+	U64PUT(p+16, dir->qid, t32);
+	p += 24;
+
+	p += stringPack(dir->uid, p);
+	p += stringPack(dir->gid, p);
+	p += stringPack(dir->mid, p);
+	
+	U32PUT(p, dir->mtime);
+	U32PUT(p+4, dir->mcount);
+	U32PUT(p+8, dir->ctime);
+	U32PUT(p+12, dir->atime);
+	U32PUT(p+16, dir->mode);
+	p += 5*4;
+
+	if(dir->qidSpace) {
+		U8PUT(p, DirQidSpaceEntry);
+		U16PUT(p+1, 2*8);
+		p += 3;
+		U64PUT(p, dir->qidOffset, t32);
+		U64PUT(p+8, dir->qidMax, t32);
+	}
+
+	assert(p == me->p + me->size);
+}
+
+
+int
+vdUnpack(VacDir *dir, MetaEntry *me)
+{
+	int t, nn, n, version;
+	uchar *p;
+	
+	p = me->p;
+	n = me->size;
+
+	memset(dir, 0, sizeof(VacDir));
+
+if(0)print("vdUnpack\n");
+	/* magic */
+	if(n < 4 || U32GET(p) != DirMagic)
+		goto Err;
+	p += 4;
+	n -= 4;
+
+if(0)print("vdUnpack: got magic\n");
+	/* version */
+	if(n < 2)
+		goto Err;
+	version = U16GET(p);
+	if(version < 7 || version > 9)
+		goto Err;
+	p += 2;
+	n -= 2;	
+
+if(0)print("vdUnpack: got version\n");
+
+	/* elem */
+	if(!stringUnpack(&dir->elem, &p, &n))
+		goto Err;
+
+if(0)print("vdUnpack: got elem\n");
+
+	/* entry  */
+	if(n < 4)
+		goto Err;
+	dir->entry = U32GET(p);
+	p += 4;
+	n -= 4;
+
+if(0)print("vdUnpack: got entry\n");
+
+	if(version < 9) {
+		dir->gen = 0;
+		dir->mentry = dir->entry+1;
+		dir->mgen = 0;
+	} else {
+		if(n < 3*4)
+			goto Err;
+		dir->gen = U32GET(p);
+		dir->mentry = U32GET(p+4);
+		dir->mgen = U32GET(p+8);
+		p += 3*4;
+		n -= 3*4;
+	}
+
+if(0)print("vdUnpack: got gen etc\n");
+
+	/* size is gotten from DirEntry */
+
+	/* qid */
+	if(n < 8)
+		goto Err;
+	dir->qid = U64GET(p);
+	p += 8;
+	n -= 8;
+
+if(0)print("vdUnpack: got qid\n");
+	/* skip replacement */
+	if(version == 7) {
+		if(n < VtScoreSize)
+			goto Err;
+		p += VtScoreSize;
+		n -= VtScoreSize;
+	}
+	
+	/* uid */
+	if(!stringUnpack(&dir->uid, &p, &n))
+		goto Err;
+
+	/* gid */
+	if(!stringUnpack(&dir->gid, &p, &n))
+		goto Err;
+
+	/* mid */
+	if(!stringUnpack(&dir->mid, &p, &n))
+		goto Err;
+
+if(0)print("vdUnpack: got ids\n");
+	if(n < 5*4)
+		goto Err;
+	dir->mtime = U32GET(p);
+	dir->mcount = U32GET(p+4);
+	dir->ctime = U32GET(p+8);
+	dir->atime = U32GET(p+12);
+	dir->mode = U32GET(p+16);
+	p += 5*4;
+	n -= 5*4;
+
+if(0)print("vdUnpack: got times\n");
+	/* optional meta data */
+	while(n > 0) {
+		if(n < 3)
+			goto Err;
+		t = p[0];
+		nn = U16GET(p+1);
+		p += 3;
+		n -= 3;
+		if(n < nn)
+			goto Err;
+		switch(t) {
+		case DirPlan9Entry:
+			/* not valid in version >= 9 */
+			if(version >= 9)
+				break;
+			if(dir->plan9 || nn != 12)
+				goto Err;
+			dir->plan9 = 1;
+			dir->p9path = U64GET(p);
+			dir->p9version = U32GET(p+8);
+			if(dir->mcount == 0)
+				dir->mcount = dir->p9version;
+			break;
+		case DirGenEntry:
+			/* not valid in version >= 9 */
+			if(version >= 9)
+				break;
+			break;
+		case DirQidSpaceEntry:
+			if(dir->qidSpace || nn != 16)
+				goto Err;
+			dir->qidSpace = 1;
+			dir->qidOffset = U64GET(p);
+			dir->qidMax = U64GET(p+8);
+			break;
+		}
+		p += nn;
+		n -= nn;
+	}
+if(0)print("vdUnpack: got options\n");
+
+	if(p != me->p + me->size)
+		goto Err;
+
+if(0)print("vdUnpack: correct size\n");
+	return 1;
+Err:
+if(0)print("vdUnpack: XXXXXXXXXXXX EbadMeta\n");
+	vtSetError(EBadMeta);
+	vdCleanup(dir);
+	return 0;
+}
diff --git a/src/cmd/vac/rtest.c b/src/cmd/vac/rtest.c
new file mode 100644
index 0000000..d45cd0f
--- /dev/null
+++ b/src/cmd/vac/rtest.c
@@ -0,0 +1,71 @@
+#include "stdinc.h"
+
+enum {
+	Nblock = 300000,
+	BlockSize = 8*1024,
+};
+
+uchar data[Nblock*VtScoreSize];
+int rflag;
+int nblock = 10000;
+int perm[Nblock];
+
+void
+main(int argc, char *argv[])
+{
+	VtSession *z;
+	int i, j, t;
+	int start;
+	uchar buf[BlockSize];
+
+	srand(time(0));
+
+	ARGBEGIN{
+	case 'r':
+		rflag++;
+		break;
+	case 'n':
+		nblock = atoi(ARGF());
+		break;
+	}ARGEND
+
+	for(i=0; i<nblock; i++)
+		perm[i] = i;
+
+	if(rflag) {
+		for(i=0; i<nblock; i++) {
+			j = nrand(nblock);
+			t = perm[j];
+			perm[j] = perm[i];
+			perm[i] = t;
+		}
+	}
+
+	if(readn(0, data, VtScoreSize*nblock) < VtScoreSize*nblock)
+		sysfatal("read failed: %r");
+
+	vtAttach();
+
+	z = vtDial("iolaire2");
+	if(z == nil)
+		sysfatal("cound not connect to venti");
+	if(!vtConnect(z, 0))
+		vtFatal("vtConnect: %s", vtGetError());
+
+	print("starting\n");
+
+	start = times(0);
+
+	if(rflag && nblock > 10000)
+		nblock = 10000;
+
+	for(i=0; i<nblock; i++) {
+		if(vtRead(z, data+perm[i]*VtScoreSize, VtDataType, buf, BlockSize) < 0)
+			vtFatal("vtRead failed: %d: %s", i, vtGetError());
+	}
+
+	print("time = %f\n", (times(0) - start)*0.001);
+
+	vtClose(z);
+	vtDetach();
+}
diff --git a/src/cmd/vac/source.c b/src/cmd/vac/source.c
new file mode 100644
index 0000000..e7245a2
--- /dev/null
+++ b/src/cmd/vac/source.c
@@ -0,0 +1,390 @@
+#include "stdinc.h"
+#include "vac.h"
+#include "dat.h"
+#include "fns.h"
+#include "error.h"
+
+static int	sizeToDepth(uvlong s, int psize, int dsize);
+
+static int
+sizeToDepth(uvlong s, int psize, int dsize)
+{
+	int np;
+	int d;
+	
+	/* determine pointer depth */
+	np = psize/VtScoreSize;
+	s = (s + dsize - 1)/dsize;
+	for(d = 0; s > 1; d++)
+		s = (s + np - 1)/np;
+	return d;
+}
+
+/* assumes u is lock? */
+Source *
+sourceAlloc(Cache *c, Lump *u, ulong block, int entry, int readOnly)
+{
+	Source *r;
+	VtEntry d;
+
+	if(u->asize < (entry+1)*VtEntrySize) {
+		vtSetError(ENoDir);
+		return nil;
+	}
+
+	if(!vtEntryUnpack(&d, u->data, entry))
+		return nil;
+	
+	if(!(d.flags & VtEntryActive)) {
+fprint(2, "bad flags %#ux %V\n", d.flags, d.score);
+		vtSetError(ENoDir);
+		return nil;
+	}
+	
+	/* HACK for backwards compatiblity - should go away at some point */
+	if(d.depth == 0) {
+if(d.size > d.dsize) fprint(2, "depth == 0! size = %ulld\n", d.size);
+		d.depth = sizeToDepth(d.size, d.psize, d.dsize);
+	}
+
+	if(d.depth < sizeToDepth(d.size, d.psize, d.dsize)) {
+		vtSetError(EBadDir);
+		return nil;
+	}
+
+	r = vtMemAllocZ(sizeof(Source));
+	r->lk = vtLockAlloc();
+	r->cache = c;
+	r->readOnly = readOnly;
+	r->lump = lumpIncRef(u);
+	r->block = block;
+	r->entry = entry;
+	r->gen = d.gen;
+	r->dir = (d.flags & VtEntryDir) != 0;
+	r->depth = d.depth;
+	r->psize = d.psize;
+	r->dsize = d.dsize;
+	r->size = d.size;
+
+	r->epb = r->dsize/VtEntrySize;
+
+	return r;
+}
+
+Source *
+sourceOpen(Source *r, ulong entry, int readOnly)
+{
+	ulong bn;
+	Lump *u;
+
+if(0)fprint(2, "sourceOpen: %V:%d: %lud\n", r->lump->score, r->entry, entry);
+	if(r->readOnly && !readOnly) {
+		vtSetError(EReadOnly);
+		return nil;
+	}
+
+	bn = entry/r->epb;
+
+	u = sourceGetLump(r, bn, readOnly, 1);
+	if(u == nil)
+		return nil;
+
+	r = sourceAlloc(r->cache, u, bn, entry%r->epb, readOnly);
+	lumpDecRef(u, 1);
+	return r;
+}
+
+Source *
+sourceCreate(Source *r, int psize, int dsize, int isdir, ulong entry)
+{
+	Source *rr;
+	int i;
+	Lump *u;
+	ulong bn;
+	VtEntry dir;
+
+	if(r->readOnly) {
+		vtSetError(EReadOnly);
+		return nil;
+	}
+
+	if(entry == 0) {
+		/*
+		 * look at a random block to see if we can find an empty entry
+		 */
+		entry = sourceGetDirSize(r);
+		entry = r->epb*lnrand(entry/r->epb+1);
+	}
+
+	/*
+	 * need to loop since multiple threads could be trying to allocate
+	 */
+	for(;;) {
+		bn = entry/r->epb;
+		sourceSetDepth(r, (uvlong)(bn+1)*r->dsize);
+		u = sourceGetLump(r, bn, 0, 1);
+		if(u == nil)
+			return nil;
+		for(i=entry%r->epb; i<r->epb; i++) {
+			vtEntryUnpack(&dir, u->data, i);
+			if((dir.flags&VtEntryActive) == 0 && dir.gen != ~0)
+				goto Found;
+		}
+		lumpDecRef(u, 1);
+		entry = sourceGetDirSize(r);
+	}
+Found:
+	/* found an entry */
+	dir.psize = psize;
+	dir.dsize = dsize;
+	dir.flags = VtEntryActive;
+	if(isdir)
+		dir.flags |= VtEntryDir;
+	dir.depth = 0;
+	dir.size = 0;
+	memmove(dir.score, vtZeroScore, VtScoreSize);
+	vtEntryPack(&dir, u->data, i);
+
+	sourceSetDirSize(r, bn*r->epb + i + 1);
+	rr = sourceAlloc(r->cache, u, bn, i, 0);
+	
+	lumpDecRef(u, 1);
+	return rr;
+}
+
+void
+sourceRemove(Source *r)
+{
+	lumpFreeEntry(r->lump, r->entry);
+	sourceFree(r);
+}
+
+int
+sourceSetDepth(Source *r, uvlong size)
+{
+	Lump *u, *v;
+	VtEntry dir;
+	int depth;
+
+	if(r->readOnly){
+		vtSetError(EReadOnly);
+		return 0;
+	}
+
+	depth = sizeToDepth(size, r->psize, r->dsize);
+
+	assert(depth >= 0);
+
+	if(depth > VtPointerDepth) {
+		vtSetError(ETooBig);
+		return 0;
+	}
+
+	vtLock(r->lk);
+
+	if(r->depth >= depth) {
+		vtUnlock(r->lk);
+		return 1;
+	}
+	
+	u = r->lump;
+	vtLock(u->lk);
+	if(!vtEntryUnpack(&dir, u->data, r->entry)) {
+		vtUnlock(u->lk);
+		vtUnlock(r->lk);
+		return 0;
+	}
+	while(dir.depth < depth) {
+		v = cacheAllocLump(r->cache, VtPointerType0+r->depth, r->psize, r->dir);
+		if(v == nil)
+			break;
+		memmove(v->data, dir.score, VtScoreSize);
+		memmove(dir.score, v->score, VtScoreSize);
+		dir.depth++;
+		vtUnlock(v->lk);
+	}
+	vtEntryPack(&dir, u->data, r->entry);
+	vtUnlock(u->lk);
+
+	r->depth = dir.depth;
+	vtUnlock(r->lk);
+
+	return dir.depth == depth;
+}
+
+int
+sourceGetVtEntry(Source *r, VtEntry *dir)
+{
+	Lump *u;
+
+	u = r->lump;
+	vtLock(u->lk);
+	if(!vtEntryUnpack(dir, u->data, r->entry)) {
+		vtUnlock(u->lk);
+		return 0;
+	}
+	vtUnlock(u->lk);
+	return 1;
+}
+
+uvlong
+sourceGetSize(Source *r)
+{
+	uvlong size;
+
+	vtLock(r->lk);
+	size = r->size;
+	vtUnlock(r->lk);
+
+	return size;
+}
+
+
+int
+sourceSetSize(Source *r, uvlong size)
+{
+	Lump *u;
+	VtEntry dir;
+	int depth;
+
+	if(r->readOnly) {
+		vtSetError(EReadOnly);
+		return 0;
+	}
+
+	if(size > VtMaxFileSize || size > ((uvlong)MaxBlock)*r->dsize) {
+		vtSetError(ETooBig);
+		return 0;
+	}
+
+	vtLock(r->lk);
+	depth = sizeToDepth(size, r->psize, r->dsize);
+	if(size < r->size) {
+		vtUnlock(r->lk);
+		return 1;
+	}
+	if(depth > r->depth) {
+		vtSetError(EBadDir);
+		vtUnlock(r->lk);
+		return 0;
+	}
+	
+	u = r->lump;
+	vtLock(u->lk);
+	vtEntryUnpack(&dir, u->data, r->entry);
+	dir.size = size;
+	vtEntryPack(&dir, u->data, r->entry);
+	vtUnlock(u->lk);
+	r->size = size;
+	vtUnlock(r->lk);
+	return 1;
+}
+
+int
+sourceSetDirSize(Source *r, ulong ds)
+{
+	uvlong size;
+
+	size = (uvlong)r->dsize*(ds/r->epb);
+	size += VtEntrySize*(ds%r->epb);
+	return sourceSetSize(r, size);
+}
+
+ulong
+sourceGetDirSize(Source *r)
+{
+	ulong ds;
+	uvlong size;
+
+	size = sourceGetSize(r);
+	ds = r->epb*(size/r->dsize);
+	ds += (size%r->dsize)/VtEntrySize;
+	return ds;
+}
+
+ulong
+sourceGetNumBlocks(Source *r)
+{
+	return (sourceGetSize(r)+r->dsize-1)/r->dsize;
+}
+
+Lump *
+sourceWalk(Source *r, ulong block, int readOnly, int *off)
+{
+	int depth;
+	int i, np;
+	Lump *u, *v;
+	int elem[VtPointerDepth+1];
+	ulong b;
+
+	if(r->readOnly && !readOnly) {
+		vtSetError(EReadOnly);
+		return nil;
+	}
+
+	vtLock(r->lk);
+	np = r->psize/VtScoreSize;
+	b = block;
+	for(i=0; i<r->depth; i++) {
+		elem[i] = b % np;
+		b /= np;
+	}
+	if(b != 0) {
+		vtUnlock(r->lk);
+		vtSetError(EBadOffset);
+		return nil;
+	}
+	elem[i] = r->entry;
+	u = lumpIncRef(r->lump);
+	depth = r->depth;
+	*off = elem[0];
+	vtUnlock(r->lk);
+
+	for(i=depth; i>0; i--) {
+		v = lumpWalk(u, elem[i], VtPointerType0+i-1, r->psize, readOnly, 0);
+		lumpDecRef(u, 0);
+		if(v == nil)
+			return nil;
+		u = v;
+	}
+
+	return u;
+}
+
+Lump *
+sourceGetLump(Source *r, ulong block, int readOnly, int lock)
+{
+	int type, off;
+	Lump *u, *v;
+
+	if(r->readOnly && !readOnly) {
+		vtSetError(EReadOnly);
+		return nil;
+	}
+	if(block == NilBlock) {
+		vtSetError(ENilBlock);
+		return nil;
+	}
+if(0)fprint(2, "sourceGetLump: %V:%d %lud\n", r->lump->score, r->entry, block);
+	u = sourceWalk(r, block, readOnly, &off);
+	if(u == nil)
+		return nil;
+	if(r->dir)
+		type = VtDirType;
+	else
+		type = VtDataType;
+	v = lumpWalk(u, off, type, r->dsize, readOnly, lock);
+	lumpDecRef(u, 0);
+	return v;
+}
+
+void
+sourceFree(Source *k)
+{
+	if(k == nil)
+		return;
+	lumpDecRef(k->lump, 0);
+	vtLockFree(k->lk);
+	memset(k, ~0, sizeof(*k));
+	vtMemFree(k);
+}
diff --git a/src/cmd/vac/srcload.c b/src/cmd/vac/srcload.c
new file mode 100644
index 0000000..4f48efc
--- /dev/null
+++ b/src/cmd/vac/srcload.c
@@ -0,0 +1,302 @@
+#include "stdinc.h"
+#include <bio.h>
+#include "vac.h"
+#include "dat.h"
+#include "fns.h"
+#include "error.h"
+
+int num = 1000;
+int length = 20*1024;
+int block= 1024;
+int bush = 4;
+int iter = 10000;
+Biobuf *bout;
+int maxdepth;
+
+Source *mkroot(Cache*);
+void new(Source*, int trace, int);
+int delete(Source*);
+void dump(Source*, int indent, ulong nentry);
+void dumpone(Source *s);
+int count(Source *s, int);
+void stats(Source *s);
+
+void
+main(int argc, char *argv[])
+{
+	int i;
+	Cache *c;
+	char *host = nil;
+	VtSession *z;
+	int csize = 10000;
+	Source *r;
+	ulong t;
+
+	t = time(0);
+	fprint(1, "time = %lud\n", t);
+
+	srand(t);
+
+	ARGBEGIN{
+	case 'i':
+		iter = atoi(ARGF());
+		break;
+	case 'n':
+		num = atoi(ARGF());
+		break;
+	case 'l':
+		length = atoi(ARGF());
+		break;
+	case 'b':	
+		block = atoi(ARGF());
+		break;
+	case 'h':
+		host = ARGF();
+		break;
+	case 'u':
+		bush = atoi(ARGF());
+		break;
+	case 'c':
+		csize = atoi(ARGF());
+		break;
+	}ARGEND;
+
+	vtAttach();
+
+	bout = vtMemAllocZ(sizeof(Biobuf));
+	Binit(bout, 1, OWRITE);
+
+	fmtinstall('V', vtScoreFmt);
+	fmtinstall('R', vtErrFmt);
+
+	z = vtDial(host);
+	if(z == nil)
+		vtFatal("could not connect to server: %s", vtGetError());
+
+	if(!vtConnect(z, 0))
+		sysfatal("vtConnect: %r");
+
+	c = cacheAlloc(z, block, csize);
+	r = mkroot(c);
+	for(i=0; i<num; i++)
+		new(r, 0, 0);
+
+	for(i=0; i<iter; i++) {
+if(i % 10000 == 0)
+stats(r);
+		new(r, 0, 0);
+		delete(r);
+	}
+
+	fprint(2, "count = %d top = %lud\n", count(r, 0), sourceGetDirSize(r));
+//	cacheCheck(c);
+fprint(2, "deleting\n");
+	for(i=0; i<num; i++)
+		delete(r);
+
+//	dump(r, 0, 0);
+	
+	lumpDecRef(r->lump, 0);
+	sourceRemove(r);
+	cacheCheck(c);
+
+	vtClose(z);
+	vtDetach();
+
+	exits(0);
+}
+
+
+Source *
+mkroot(Cache *c)
+{
+	Lump *u;
+	VtEntry *dir;
+	Source *r;
+
+	u = cacheAllocLump(c, VtDirType, cacheGetBlockSize(c), 1);
+	dir = (VtEntry*)u->data;
+	vtPutUint16(dir->psize, cacheGetBlockSize(c));
+	vtPutUint16(dir->dsize, cacheGetBlockSize(c));
+	dir->flag = VtEntryActive|VtEntryDir;
+	memmove(dir->score, vtZeroScore, VtScoreSize);
+	
+	r = sourceAlloc(c, u, 0, 0);
+	vtUnlock(u->lk);
+	if(r == nil)
+		sysfatal("could not create root source: %R");
+	return r;
+}
+
+void
+new(Source *s, int trace, int depth)
+{
+	int i, n;
+	Source *ss;
+	
+	if(depth > maxdepth)
+		maxdepth = depth;
+
+	n = sourceGetDirSize(s);
+	for(i=0; i<n; i++) {
+		ss = sourceOpen(s, nrand(n), 0);
+		if(ss == nil)
+			continue;
+		if(ss->dir && frand() < 1./bush) {
+			if(trace) {
+				int j;
+				for(j=0; j<trace; j++)
+					Bprint(bout, " ");
+				Bprint(bout, "decend %d\n", i);
+			}
+			new(ss, trace?trace+1:0, depth+1);
+			sourceFree(ss);
+			return;
+		}
+		sourceFree(ss);
+	}
+	ss = sourceCreate(s, s->psize, s->dsize, 1+frand()>.5, 0);
+	if(ss == nil)
+		fprint(2, "could not create directory: %R\n");
+	if(trace) {
+		int j;
+		for(j=1; j<trace; j++)
+			Bprint(bout, " ");
+		Bprint(bout, "create %d %V\n", ss->entry, ss->lump->score);
+	}
+	sourceFree(ss);
+}
+
+int
+delete(Source *s)
+{
+	int i, n;
+	Source *ss;
+	
+	assert(s->dir);
+
+	n = sourceGetDirSize(s);
+	/* check if empty */
+	for(i=0; i<n; i++) {
+		ss = sourceOpen(s, i, 1);
+		if(ss != nil) {
+			sourceFree(ss);
+			break;
+		}
+	}
+	if(i == n)
+		return 0;
+		
+	for(;;) {
+		ss = sourceOpen(s, nrand(n), 0);
+		if(ss == nil)
+			continue;
+		if(ss->dir && delete(ss)) {
+			sourceFree(ss);
+			return 1;
+		}
+		if(1)
+			break;
+		sourceFree(ss);
+	}
+
+
+	sourceRemove(ss);
+	return 1;
+}
+
+void
+dumpone(Source *s)
+{
+	ulong i, n;
+	Source *ss;
+
+	Bprint(bout, "gen %4lud depth %d %V", s->gen, s->depth, s->lump->score);
+	if(!s->dir) {
+		Bprint(bout, " data size: %llud\n", s->size);
+		return;
+	}
+	n = sourceGetDirSize(s);
+	Bprint(bout, " dir size: %lud\n", n);
+	for(i=0; i<n; i++) {
+		ss = sourceOpen(s, i, 1);
+		if(ss == nil) {
+fprint(2, "%lud: %R\n", i);
+			continue;
+		}
+		Bprint(bout, "\t%lud %d %llud %V\n", i, ss->dir, ss->size, ss->lump->score);
+		sourceFree(ss);
+	}
+	return;
+}
+
+
+void
+dump(Source *s, int ident, ulong entry)
+{
+	ulong i, n;
+	Source *ss;
+
+	for(i=0; i<ident; i++)
+		Bprint(bout, " ");
+	Bprint(bout, "%4lud: gen %4lud depth %d", entry, s->gen, s->depth);
+	if(!s->dir) {
+		Bprint(bout, " data size: %llud\n", s->size);
+		return;
+	}
+	n = sourceGetDirSize(s);
+	Bprint(bout, " dir size: %lud\n", n);
+	for(i=0; i<n; i++) {
+		ss = sourceOpen(s, i, 1);
+		if(ss == nil)
+			continue;
+		dump(ss, ident+1, i);
+		sourceFree(ss);
+	}
+	return;
+}
+
+int
+count(Source *s, int rec)
+{
+	ulong i, n;
+	int c;
+	Source *ss;
+
+	if(!s->dir)
+		return 0;
+	n = sourceGetDirSize(s);
+	c = 0;
+	for(i=0; i<n; i++) {
+		ss = sourceOpen(s, i, 1);
+		if(ss == nil)
+			continue;
+		if(rec)
+			c += count(ss, rec);
+		c++;
+		sourceFree(ss);
+	}
+	return c;
+}
+
+void
+stats(Source *s)
+{
+	int n, i, c, cc, max;
+	Source *ss;
+
+	cc = 0;
+	max = 0;
+	n = sourceGetDirSize(s);
+	for(i=0; i<n; i++) {
+		ss = sourceOpen(s, i, 1);
+		if(ss == nil)
+			continue;
+		cc++;
+		c = count(ss, 1);
+		if(c > max)
+			max = c;
+		sourceFree(ss);
+	}
+fprint(2, "count = %d top = %d depth=%d maxcount %d\n", cc, n, maxdepth, max);
+}
diff --git a/src/cmd/vac/stdinc.h b/src/cmd/vac/stdinc.h
new file mode 100644
index 0000000..aca405f
--- /dev/null
+++ b/src/cmd/vac/stdinc.h
@@ -0,0 +1,8 @@
+#include <u.h>
+#include <libc.h>
+
+#include "venti.h"
+
+typedef uvlong	u64int;
+typedef	uchar	u8int;
+typedef ushort	u16int;
diff --git a/src/cmd/vac/util.c b/src/cmd/vac/util.c
new file mode 100644
index 0000000..f52acf6
--- /dev/null
+++ b/src/cmd/vac/util.c
@@ -0,0 +1,71 @@
+#include "stdinc.h"
+#include "vac.h"
+#include "dat.h"
+#include "fns.h"
+
+int
+vtGetUint16(uchar *p)
+{
+	return (p[0]<<8)|p[1];
+}
+
+ulong
+vtGetUint32(uchar *p)
+{
+	return (p[0]<<24)|(p[1]<<16)|(p[2]<<8)|p[3];
+}
+
+uvlong
+vtGetUint48(uchar *p)
+{
+	return ((uvlong)p[0]<<40)|((uvlong)p[1]<<32)|
+		(p[2]<<24)|(p[3]<<16)|(p[4]<<8)|p[5];
+}
+
+uvlong
+vtGetUint64(uchar *p)
+{
+	return ((uvlong)p[0]<<56)|((uvlong)p[1]<<48)|((uvlong)p[2]<<40)|
+		((uvlong)p[3]<<32)|(p[4]<<24)|(p[5]<<16)|(p[6]<<8)|p[7];
+}
+
+
+void
+vtPutUint16(uchar *p, int x)
+{
+	p[0] = x>>8;
+	p[1] = x;
+}
+
+void
+vtPutUint32(uchar *p, ulong x)
+{
+	p[0] = x>>24;
+	p[1] = x>>16;
+	p[2] = x>>8;
+	p[3] = x;
+}
+
+void
+vtPutUint48(uchar *p, uvlong x)
+{
+	p[0] = x>>40;
+	p[1] = x>>32;
+	p[2] = x>>24;
+	p[3] = x>>16;
+	p[4] = x>>8;
+	p[5] = x;
+}
+
+void
+vtPutUint64(uchar *p, uvlong x)
+{
+	p[0] = x>>56;
+	p[1] = x>>48;
+	p[2] = x>>40;
+	p[3] = x>>32;
+	p[4] = x>>24;
+	p[5] = x>>16;
+	p[6] = x>>8;
+	p[7] = x;
+}
diff --git a/src/cmd/vac/vac-orig.c b/src/cmd/vac/vac-orig.c
new file mode 100644
index 0000000..c38365b
--- /dev/null
+++ b/src/cmd/vac/vac-orig.c
@@ -0,0 +1,1213 @@
+#include "stdinc.h"
+#include "vac.h"
+#include "dat.h"
+#include "fns.h"
+
+typedef struct Sink Sink;
+typedef struct MetaSink MetaSink;
+typedef struct DirSink DirSink;
+
+struct Sink {
+	VtSession *z;
+	VtEntry dir;
+	uchar *buf;
+	uchar *pbuf[VtPointerDepth+1];
+};
+
+struct DirSink {
+	Sink *sink;
+	MetaSink *msink;
+	ulong nentry;
+	uchar *buf;
+	uchar *p;	/* current pointer */
+	uchar *ep;	/* end pointer */
+};
+
+struct MetaSink {
+	Sink *sink;
+	uchar *buf;
+	int maxindex;
+	int nindex;
+	uchar *rp;	/* start of current record */
+	uchar *p;	/* current pointer */
+	uchar *ep;	/* end pointer */
+};
+
+static void usage(void);
+static int strpCmp(void*, void*);
+static void warn(char *fmt, ...);
+static void cleanup(void);
+static u64int unittoull(char *s);
+static int vac(VtSession *z, char *argv[]);
+static void vacFile(DirSink *dsink, char *lname, char *sname, VacFile*);
+static void vacStdin(DirSink *dsink, char *name, VacFile *vf);
+static void vacData(DirSink *dsink, int fd, char *lname, VacFile*, Dir*);
+static void vacDir(DirSink *dsink, int fd, char *lname, char *sname, VacFile*);
+static int vacMerge(DirSink *dsink, char *lname, char *sname);
+
+Sink *sinkAlloc(VtSession *z, int psize, int dsize);
+void sinkWrite(Sink *k, uchar *data, int n);
+void sinkWriteScore(Sink *k, uchar *score, int n);
+void sinkClose(Sink *k);
+void sinkFree(Sink *k);
+
+DirSink *dirSinkAlloc(VtSession *z, int psize, int dsize);
+void dirSinkWrite(DirSink *k, VtEntry*);
+void dirSinkWriteSink(DirSink *k, Sink*);
+int dirSinkWriteFile(DirSink *k, VacFile *vf);
+void dirSinkClose(DirSink *k);
+void dirSinkFree(DirSink *k);
+
+MetaSink *metaSinkAlloc(VtSession *z, int psize, int dsize);
+void metaSinkPutc(MetaSink *k, int c);
+void metaSinkPutString(MetaSink *k, char *s);
+void metaSinkPutUint32(MetaSink *k, ulong x);
+void metaSinkPutUint64(MetaSink *k, uvlong x);
+void metaSinkWrite(MetaSink *k, uchar *data, int n);
+void metaSinkWriteDir(MetaSink *ms, VacDir *vd);
+void metaSinkEOR(MetaSink *k);
+void metaSinkClose(MetaSink *k);
+void metaSinkFree(MetaSink *k);
+void plan9ToVacDir(VacDir*, Dir*, ulong entry, uvlong qid);
+
+enum {
+	Version = 8,
+	BlockSize = 8*1024,
+	MaxExclude = 1000,
+};
+
+struct {
+	ulong	file;
+	ulong	sfile;
+	ulong	data;
+	ulong	sdata;
+	ulong	skip;
+	ulong	meta;
+} stats;
+
+int bsize = BlockSize;
+int maxbsize;
+char *oname, *dfile;
+int verbose;
+uvlong fileid = 1;
+int qdiff;
+char *exclude[MaxExclude];
+int nexclude;
+int nowrite;
+int merge;
+char *isi;
+
+void
+main(int argc, char *argv[])
+{
+	VtSession *z;
+	char *p;
+	char *host = nil;
+	int statsFlag = 0;
+
+	atexit(cleanup);
+
+	ARGBEGIN{
+	default:
+		usage();
+	case 'b':
+		p = ARGF();
+		if(p == 0)
+			usage();
+		bsize = unittoull(p);
+		if(bsize == ~0)
+			usage();
+		break;
+	case 'd':
+		dfile = ARGF();
+		if(dfile == nil)
+			usage();
+		break;
+	case 'e':
+		if(nexclude >= MaxExclude)
+			sysfatal("too many exclusions\n");
+		exclude[nexclude] = ARGF();
+		if(exclude[nexclude] == nil)
+			usage();
+		nexclude++;
+		break;
+	case 'f':
+		oname = ARGF();
+		if(oname == 0)
+			usage();
+		break;
+	case 'h':
+		host = ARGF();
+		if(host == nil)
+			usage();
+		break;
+	case 'i':
+		isi = ARGF();
+		if(isi == nil)
+			usage();
+		break;
+	case 'n':
+		nowrite++;
+		break;
+	case 'm':
+		merge++;
+		break;
+	case 'q':
+		qdiff++;
+		break;
+	case 's':
+		statsFlag++;
+		break;
+	case 'v':
+		verbose++;
+		break;
+	}ARGEND;
+
+	if(bsize < 512)
+		bsize = 512;
+	if(bsize > VtMaxLumpSize)
+		bsize = VtMaxLumpSize;
+	maxbsize = bsize;
+
+	vtAttach();
+
+	fmtinstall('V', vtScoreFmt);
+	fmtinstall('R', vtErrFmt);
+
+	z = vtDial(host, 0);
+	if(z == nil)
+		vtFatal("could not connect to server: %R");
+
+	if(!vtConnect(z, 0))
+		vtFatal("vtConnect: %R");
+
+	qsort(exclude, nexclude, sizeof(char*), strpCmp);
+
+	vac(z, argv);
+	if(!vtSync(z))
+		fprint(2, "warning: could not ask server to flush pending writes: %R\n");
+
+	if(statsFlag)
+		fprint(2, "files %ld:%ld data %ld:%ld:%ld meta %ld\n", stats.file, stats.sfile,
+			stats.data, stats.skip, stats.sdata, stats.meta);
+//packetStats();
+	vtClose(z);
+	vtDetach();
+
+	exits(0);
+}
+
+void
+static usage(void)
+{
+	fprint(2, "usage: %s [-amqsv] [-h host] [-d vacfile] [-b blocksize] [-i name] [-e exclude] [-f vacfile] file ... \n", argv0);
+	exits("usage");
+}
+
+static
+int strpCmp(void *p0, void *p1)
+{
+	return strcmp(*(char**)p0, *(char**)p1);
+}
+
+
+int
+readBlock(int fd, uchar *buf, int n)
+{
+	int m, t = 0;
+
+	while(t < n){
+		m = read(fd, buf+t, n-t);
+		if(m < 0)
+			return -1;
+		if(m == 0)
+			break;
+		t += m;
+	}
+	return t;
+}
+
+int
+vacWrite(VtSession *z, uchar score[VtScoreSize], int type, uchar *buf, int n)
+{
+assert(n > 0);
+	if(nowrite) {
+		vtSha1(score, buf, n);
+		return 1;
+	}
+	if(!vtWrite(z, score, type, buf, n))
+		return 0;
+	if(!vtSha1Check(score, buf, n)) {
+		uchar score2[VtScoreSize];
+		
+		vtSha1(score2, buf, n);
+fprint(2, "vtSha1Check: n = %d %V %V\n", n, score, score2);
+		vtSetError("vtSha1Check failed");
+		return 0;
+	}
+	return 1;
+}
+
+
+static int
+vac(VtSession *z, char *argv[])
+{
+	DirSink *dsink, *ds;
+	MetaSink *ms;
+	VtRoot root;
+	uchar score[VtScoreSize], buf[VtRootSize];
+	char cwd[2048];
+	int cd, i;
+	char *cp2, *cp;
+	VacFS *fs;
+	VacFile *vff;
+	int fd;
+	Dir *dir;
+	VacDir vd;
+
+	if(getwd(cwd, sizeof(cwd)) == 0)
+		sysfatal("can't find current directory: %r\n");
+
+	dsink = dirSinkAlloc(z, bsize, bsize);
+
+	fs = nil;
+	if(dfile != nil) {
+		fs = vfsOpen(z, dfile, 1, 10000);
+		if(fs == nil)
+			fprint(2, "could not open diff: %s: %s\n", dfile, vtGetError());
+	}
+		
+
+	if(oname != nil) {
+		fd = create(oname, OWRITE, 0666);
+		if(fd < 0)
+			sysfatal("could not create file: %s: %r", oname);
+	} else 
+		fd = 1;
+
+	dir = dirfstat(fd);
+	if(dir == nil)
+		sysfatal("dirfstat failed: %r");
+
+	for(; *argv; argv++) {
+		cp2 = *argv;
+		cd = 0;
+		for (cp = *argv; *cp; cp++)
+			if (*cp == '/')
+				cp2 = cp;
+		if (cp2 != *argv) {
+			*cp2 = '\0';
+			chdir(*argv);
+			*cp2 = '/';
+			cp2++;
+			cd = 1;
+		}
+		vff = nil;
+		if(fs)
+			vff = vfOpen(fs, cp2);
+		vacFile(dsink, argv[0], cp2, vff);
+		if(vff)
+			vfDecRef(vff);
+		if(cd && chdir(cwd) < 0)
+			sysfatal("can't cd back to %s: %r\n", cwd);
+	}
+	
+	if(isi) {
+		vff = nil;
+		if(fs)
+			vff = vfOpen(fs, isi);
+		vacStdin(dsink, isi, vff);
+		if(vff)
+			vfDecRef(vff);
+	}
+
+	dirSinkClose(dsink);
+
+	/* build meta information for the root */
+	ms = metaSinkAlloc(z, bsize, bsize);
+	/* fake into a directory */
+	dir->mode |= (dir->mode&0444)>>2;
+	dir->qid.type |= QTDIR;
+	dir->mode |= DMDIR;
+	plan9ToVacDir(&vd, dir, 0, fileid++);
+	if(strcmp(vd.elem, "/") == 0){
+		vtMemFree(vd.elem);
+		vd.elem = vtStrDup("root");
+	}
+	metaSinkWriteDir(ms, &vd);
+	vdCleanup(&vd);
+	metaSinkClose(ms);
+	
+	ds = dirSinkAlloc(z, bsize, bsize);
+	dirSinkWriteSink(ds, dsink->sink);
+	dirSinkWriteSink(ds, dsink->msink->sink);
+	dirSinkWriteSink(ds, ms->sink);
+	dirSinkClose(ds);
+
+	memset(&root, 0, sizeof(root));		
+	root.version = VtRootVersion;
+	strncpy(root.name, dir->name, sizeof(root.name));
+	root.name[sizeof(root.name)-1] = 0;
+	free(dir);
+	sprint(root.type, "vac");
+	memmove(root.score, ds->sink->dir.score, VtScoreSize);
+	root.blockSize = maxbsize;
+	if(fs != nil)
+		vfsGetScore(fs, root.prev);
+
+	metaSinkFree(ms);
+	dirSinkFree(ds);
+	dirSinkFree(dsink);
+	if(fs != nil)
+		vfsClose(fs);
+	
+	vtRootPack(&root, buf);
+	if(!vacWrite(z, score, VtRootType, buf, VtRootSize))
+		vtFatal("vacWrite failed: %s", vtGetError());
+
+	fprint(fd, "vac:");
+	for(i=0; i<VtScoreSize; i++)
+		fprint(fd, "%.2x", score[i]);
+	fprint(fd, "\n");
+	
+	/* avoid remove at cleanup */
+	oname = nil;
+	return 1;
+}
+
+static int
+isExcluded(char *name)
+{
+	int bot, top, i, x;
+
+	bot = 0;	
+	top = nexclude;
+	while(bot < top) {
+		i = (bot+top)>>1;
+		x = strcmp(exclude[i], name);
+		if(x == 0)
+			return 1;
+		if(x < 0)
+			bot = i + 1;
+		else /* x > 0 */
+			top = i;
+	}
+	return 0;
+}
+
+static void
+vacFile(DirSink *dsink, char *lname, char *sname, VacFile *vf)
+{
+	int fd;
+	Dir *dir;
+	VacDir vd;
+	ulong entry;
+
+	if(isExcluded(lname)) {
+		warn("excluding: %s", lname);
+		return;
+	}
+
+	if(merge && vacMerge(dsink, lname, sname))
+		return;
+
+	fd = open(sname, OREAD);
+	if(fd < 0) {
+		warn("could not open file: %s: %s", lname, vtOSError());
+		return;
+	}
+
+	if(verbose)
+		fprint(2, "%s\n", lname);
+
+	dir = dirfstat(fd);
+	if(dir == nil) {
+		warn("can't stat %s: %r", lname);
+		close(fd);
+		return;
+	}
+
+	entry = dsink->nentry;
+
+	if(dir->mode & DMDIR) 
+		vacDir(dsink, fd, lname, sname, vf);
+	else
+		vacData(dsink, fd, lname, vf, dir);
+
+	plan9ToVacDir(&vd, dir, entry, fileid++);
+	metaSinkWriteDir(dsink->msink, &vd);
+	vdCleanup(&vd);
+
+	free(dir);
+	close(fd);
+}
+
+static void
+vacStdin(DirSink *dsink, char *name, VacFile *vf)
+{
+	Dir *dir;
+	VacDir vd;
+	ulong entry;
+
+	if(verbose)
+		fprint(2, "%s\n", "<stdio>");
+
+	dir = dirfstat(0);
+	if(dir == nil) {
+		warn("can't stat <stdio>: %r");
+		return;
+	}
+
+	entry = dsink->nentry;
+
+	vacData(dsink, 0, "<stdin>", vf, dir);
+
+	plan9ToVacDir(&vd, dir, entry, fileid++);
+	vd.elem = vtStrDup(name);
+	metaSinkWriteDir(dsink->msink, &vd);
+	vdCleanup(&vd);
+
+	free(dir);
+}
+
+static ulong
+vacDataSkip(Sink *sink, VacFile *vf, int fd, ulong blocks, uchar *buf, char *lname)
+{
+	int n;
+	ulong i;
+	uchar score[VtScoreSize];
+
+	/* skip blocks for append only files */
+	if(seek(fd, (blocks-1)*bsize, 0) != (blocks-1)*bsize) {
+		warn("error seeking: %s", lname);
+		goto Err;
+	}
+	n = readBlock(fd, buf, bsize);
+	if(n < bsize) {
+		warn("error checking append only file: %s", lname);
+		goto Err;
+	}
+	if(!vfGetBlockScore(vf, blocks-1, score) || !vtSha1Check(score, buf, n)) {
+		warn("last block of append file did not match: %s", lname);
+		goto Err;
+	}
+
+	for(i=0; i<blocks; i++) {
+		if(!vfGetBlockScore(vf, i, score)) {
+			warn("could not get score: %s: %lud", lname, i);
+			seek(fd, i*bsize, 0);
+			return i;
+		}
+		stats.skip++;
+		sinkWriteScore(sink, score, bsize);
+	}
+
+	return i;
+Err:
+	seek(fd, 0, 0);
+	return 0;
+}
+
+static void
+vacData(DirSink *dsink, int fd, char *lname, VacFile *vf, Dir *dir)
+{
+	uchar *buf;
+	Sink *sink;
+	int n;
+	uchar score[VtScoreSize];
+	ulong block, same;
+	VacDir vd;
+	ulong vfblocks;
+
+	vfblocks = 0;
+	if(vf != nil && qdiff) {
+		vfGetDir(vf, &vd);
+		if(vd.mtime == dir->mtime)
+		if(vd.size == dir->length)
+		if(!vd.plan9 || /* vd.p9path == dir->qid.path && */ vd.p9version == dir->qid.vers)
+		if(dirSinkWriteFile(dsink, vf)) {
+			stats.sfile++;
+			vdCleanup(&vd);
+			return;
+		}
+
+		/* look for an append only file */
+		if((dir->mode&DMAPPEND) != 0)
+		if(vd.size < dir->length)
+		if(vd.plan9)
+		if(vd.p9path == dir->qid.path)
+			vfblocks = vd.size/bsize;
+
+		vdCleanup(&vd);
+	}
+	stats.file++;
+
+	buf = vtMemAlloc(bsize);
+	sink = sinkAlloc(dsink->sink->z, bsize, bsize);
+	block = 0;
+	same = stats.sdata+stats.skip;
+
+	if(vfblocks > 1)
+		block += vacDataSkip(sink, vf, fd, vfblocks, buf, lname);
+
+if(0) fprint(2, "vacData: %s: %ld\n", lname, block);
+	for(;;) {
+		n = readBlock(fd, buf, bsize);
+		if(0 && n < 0)
+			warn("file truncated due to read error: %s: %s", lname, vtOSError());
+		if(n <= 0)
+			break;
+		if(vf != nil && vfGetBlockScore(vf, block, score) && vtSha1Check(score, buf, n)) {
+			stats.sdata++;
+			sinkWriteScore(sink, score, n);
+		} else
+			sinkWrite(sink, buf, n);
+		block++;
+	}
+	same = stats.sdata+stats.skip - same;
+
+	if(same && (dir->mode&DMAPPEND) != 0)
+		if(0)fprint(2, "%s: total %lud same %lud:%lud diff %lud\n",
+			lname, block, same, vfblocks, block-same);
+
+	sinkClose(sink);
+	dirSinkWriteSink(dsink, sink);
+	sinkFree(sink);
+	free(buf);
+}
+
+
+static void
+vacDir(DirSink *dsink, int fd, char *lname, char *sname, VacFile *vf)
+{
+	Dir *dirs;
+	char *ln, *sn;
+	int i, nd;
+	DirSink *ds;
+	VacFile *vvf;
+	char *name;
+
+	ds = dirSinkAlloc(dsink->sink->z, bsize, bsize);
+	while((nd = dirread(fd, &dirs)) > 0){
+		for(i = 0; i < nd; i++){
+			name = dirs[i].name;
+			/* check for bad file names */
+			if(name[0] == 0 || strcmp(name, ".") == 0 || strcmp(name, "..") == 0)
+				continue;
+			ln = vtMemAlloc(strlen(lname) + strlen(name) + 2);
+			sn = vtMemAlloc(strlen(sname) + strlen(name) + 2);
+			sprint(ln, "%s/%s", lname, name);
+			sprint(sn, "%s/%s", sname, name);
+			if(vf != nil)
+				vvf = vfWalk(vf, name);
+			else
+				vvf = nil;
+			vacFile(ds, ln, sn, vvf);
+			if(vvf != nil)
+				vfDecRef(vvf);
+			vtMemFree(ln);
+			vtMemFree(sn);
+		}
+		free(dirs);
+	}
+	dirSinkClose(ds);
+	dirSinkWriteSink(dsink, ds->sink);
+	dirSinkWriteSink(dsink, ds->msink->sink);
+	dirSinkFree(ds);
+}
+
+static int
+vacMergeFile(DirSink *dsink, VacFile *vf, VacDir *dir, uvlong offset, uvlong *max)
+{
+	uchar buf[VtEntrySize];
+	VtEntry dd, md;
+	int e;
+
+	if(vfRead(vf, buf, VtEntrySize, (uvlong)dir->entry*VtEntrySize) != VtEntrySize) {
+		warn("could not read venti dir entry: %s\n", dir->elem);
+		return 0;
+	}
+	vtEntryUnpack(&dd, buf, 0);
+
+	if(dir->mode & ModeDir)	{
+		e = dir->mentry;
+		if(e == 0)
+			e = dir->entry + 1;
+		
+		if(vfRead(vf, buf, VtEntrySize, e*VtEntrySize) != VtEntrySize) {
+			warn("could not read venti dir entry: %s\n", dir->elem);
+			return 0;
+		}
+		vtEntryUnpack(&md, buf, 0);
+	}
+
+	/* max might incorrect in some old dumps */
+	if(dir->qid >= *max) {
+		warn("qid out of range: %s", dir->elem);
+		*max = dir->qid;
+	}
+
+	dir->qid += offset;
+	dir->entry = dsink->nentry;
+
+	if(dir->qidSpace) {
+		dir->qidOffset += offset;
+	} else {
+		dir->qidSpace = 1;
+		dir->qidOffset = offset;
+		dir->qidMax = *max;
+	}
+
+	dirSinkWrite(dsink, &dd);
+	if(dir->mode & ModeDir)	
+		dirSinkWrite(dsink, &md);
+	metaSinkWriteDir(dsink->msink, dir);
+	
+	return 1;
+}
+
+static int
+vacMerge(DirSink *dsink, char *lname, char *sname)
+{
+	char *p;
+	VacFS *fs;
+	VacFile *vf;
+	VacDirEnum *d;
+	VacDir dir;
+	uvlong max;
+
+	p = strrchr(sname, '.');
+	if(p == 0 || strcmp(p, ".vac"))
+		return 0;
+
+	d = nil;
+	fs = vfsOpen(dsink->sink->z, sname, 1, 100);
+	if(fs == nil)
+		return 0;
+
+	vf = vfOpen(fs, "/");
+	if(vf == nil)
+		goto Done;
+	max = vfGetId(vf);
+	d = vdeOpen(fs, "/");
+	if(d == nil)
+		goto Done;
+
+	if(verbose)
+		fprint(2, "merging: %s\n", lname);
+
+	if(maxbsize < vfsGetBlockSize(fs))
+		maxbsize = vfsGetBlockSize(fs);
+
+	for(;;) {
+		if(vdeRead(d, &dir, 1) < 1)
+			break;
+		vacMergeFile(dsink, vf, &dir, fileid, &max);
+		vdCleanup(&dir);	
+	}
+	fileid += max;
+
+Done:
+	if(d != nil)
+		vdeFree(d);
+	if(vf != nil)
+		vfDecRef(vf);
+	vfsClose(fs);
+	return 1;
+}
+
+Sink *
+sinkAlloc(VtSession *z, int psize, int dsize)
+{
+	Sink *k;
+	int i;
+
+	if(psize < 512 || psize > VtMaxLumpSize)
+		vtFatal("sinkAlloc: bad psize");
+	if(dsize < 512 || dsize > VtMaxLumpSize)
+		vtFatal("sinkAlloc: bad psize");
+
+	psize = VtScoreSize*(psize/VtScoreSize);
+
+	k = vtMemAllocZ(sizeof(Sink));
+	k->z = z;
+	k->dir.flags = VtEntryActive;
+	k->dir.psize = psize;
+	k->dir.dsize = dsize;
+	k->buf = vtMemAllocZ(VtPointerDepth*k->dir.psize + VtScoreSize);
+	for(i=0; i<=VtPointerDepth; i++)
+		k->pbuf[i] = k->buf + i*k->dir.psize;
+	return k;
+}
+
+void
+sinkWriteScore(Sink *k, uchar score[VtScoreSize], int n)
+{
+	int i;
+	uchar *p;
+	VtEntry *d;
+
+	memmove(k->pbuf[0], score, VtScoreSize);
+
+	d = &k->dir;
+
+	for(i=0; i<VtPointerDepth; i++) {
+		k->pbuf[i] += VtScoreSize;
+		if(k->pbuf[i] < k->buf + d->psize*(i+1))
+			break;
+		if(i == VtPointerDepth-1)
+			vtFatal("file too big");
+		p = k->buf+i*d->psize;
+		stats.meta++;
+		if(!vacWrite(k->z, k->pbuf[i+1], VtPointerType0+i, p, d->psize))
+			vtFatal("vacWrite failed: %s", vtGetError());
+		k->pbuf[i] = p;
+	}
+
+	/* round size up to multiple of dsize */
+	d->size = d->dsize * ((d->size + d->dsize-1)/d->dsize);
+	
+	d->size += n;
+}
+
+void
+sinkWrite(Sink *k, uchar *p, int n)
+{
+	int type;
+	uchar score[VtScoreSize];
+
+	if(n > k->dir.dsize)
+		vtFatal("sinkWrite: size too big");
+
+	if(k->dir.flags & VtEntryDir) {
+		type = VtDirType;
+		stats.meta++;
+	} else {
+		type = VtDataType;
+		stats.data++;
+	}
+	if(!vacWrite(k->z, score, type, p, n))
+		vtFatal("vacWrite failed: %s", vtGetError());
+
+	sinkWriteScore(k, score, n);
+}
+
+static int
+sizeToDepth(uvlong s, int psize, int dsize)
+{
+	int np;
+	int d;
+	
+	/* determine pointer depth */
+	np = psize/VtScoreSize;
+	s = (s + dsize - 1)/dsize;
+	for(d = 0; s > 1; d++)
+		s = (s + np - 1)/np;
+	return d;
+}
+
+void
+sinkClose(Sink *k)
+{
+	int i, n;
+	uchar *p;
+	VtEntry *kd;
+
+	kd = &k->dir;
+
+	/* empty */
+	if(kd->size == 0) {
+		memmove(kd->score, vtZeroScore, VtScoreSize);
+		return;
+	}
+
+	for(n=VtPointerDepth-1; n>0; n--)
+		if(k->pbuf[n] > k->buf + kd->psize*n)
+			break;
+
+	kd->depth = sizeToDepth(kd->size, kd->psize, kd->dsize);
+
+	/* skip full part of tree */
+	for(i=0; i<n && k->pbuf[i] == k->buf + kd->psize*i; i++)
+		;
+
+	/* is the tree completely full */
+	if(i == n && k->pbuf[n] == k->buf + kd->psize*n + VtScoreSize) {
+		memmove(kd->score, k->pbuf[n] - VtScoreSize, VtScoreSize);
+		return;
+	}
+	n++;
+
+	/* clean up the edge */
+	for(; i<n; i++) {
+		p = k->buf+i*kd->psize;
+		stats.meta++;
+		if(!vacWrite(k->z, k->pbuf[i+1], VtPointerType0+i, p, k->pbuf[i]-p))
+			vtFatal("vacWrite failed: %s", vtGetError());
+		k->pbuf[i+1] += VtScoreSize;
+	}
+	memmove(kd->score, k->pbuf[i] - VtScoreSize, VtScoreSize);
+}
+
+void
+sinkFree(Sink *k)
+{
+	vtMemFree(k->buf);
+	vtMemFree(k);
+}
+
+DirSink *
+dirSinkAlloc(VtSession *z, int psize, int dsize)
+{
+	DirSink *k;
+	int ds;
+
+	ds = VtEntrySize*(dsize/VtEntrySize);
+
+	k = vtMemAllocZ(sizeof(DirSink));
+	k->sink = sinkAlloc(z, psize, ds);
+	k->sink->dir.flags |= VtEntryDir;
+	k->msink = metaSinkAlloc(z, psize, dsize);
+	k->buf = vtMemAlloc(ds);
+	k->p = k->buf;
+	k->ep = k->buf + ds;
+	return k;
+}
+
+void
+dirSinkWrite(DirSink *k, VtEntry *dir)
+{
+	if(k->p + VtEntrySize > k->ep) {
+		sinkWrite(k->sink, k->buf, k->p - k->buf);
+		k->p = k->buf;
+	}
+	vtEntryPack(dir, k->p, 0);
+	k->nentry++;
+	k->p += VtEntrySize;
+}
+
+void
+dirSinkWriteSink(DirSink *k, Sink *sink)
+{
+	dirSinkWrite(k, &sink->dir);
+}
+
+int
+dirSinkWriteFile(DirSink *k, VacFile *vf)
+{
+	VtEntry dir;
+
+	if(!vfGetVtEntry(vf, &dir))
+		return 0;
+	dirSinkWrite(k, &dir);
+	return 1;
+}
+
+void
+dirSinkClose(DirSink *k)
+{
+	metaSinkClose(k->msink);
+	if(k->p != k->buf)
+		sinkWrite(k->sink, k->buf, k->p - k->buf);
+	sinkClose(k->sink);
+}
+
+void
+dirSinkFree(DirSink *k)
+{
+	sinkFree(k->sink);
+	metaSinkFree(k->msink);
+	vtMemFree(k->buf);
+	vtMemFree(k);
+}
+
+MetaSink *
+metaSinkAlloc(VtSession *z, int psize, int dsize)
+{
+	MetaSink *k;
+
+	k = vtMemAllocZ(sizeof(MetaSink));
+	k->sink = sinkAlloc(z, psize, dsize);
+	k->buf = vtMemAlloc(dsize);
+	k->maxindex = dsize/100;	/* 100 byte entries seems reasonable */
+	if(k->maxindex < 1)
+		k->maxindex = 1;
+	k->rp = k->p = k->buf + MetaHeaderSize + k->maxindex*MetaIndexSize;
+	k->ep = k->buf + dsize;
+	return k;
+}
+
+/* hack to get base to compare routine - not reentrant */
+uchar *blockBase;
+
+int
+dirCmp(void *p0, void *p1)
+{
+	uchar *q0, *q1;
+	int n0, n1, r;
+
+	/* name is first element of entry */
+	q0 = p0;
+	q0 = blockBase + (q0[0]<<8) + q0[1];
+	n0 = (q0[6]<<8) + q0[7];
+	q0 += 8;
+
+	q1 = p1;
+	q1 = blockBase + (q1[0]<<8) + q1[1];
+	n1 = (q1[6]<<8) + q1[7];
+	q1 += 8;
+
+	if(n0 == n1)
+		return memcmp(q0, q1, n0);
+	else if (n0 < n1) {
+		r = memcmp(q0, q1, n0);
+		return (r==0)?1:r;
+	} else  {
+		r = memcmp(q0, q1, n1);
+		return (r==0)?-1:r;
+	}
+}
+
+void
+metaSinkFlush(MetaSink *k)
+{
+	uchar *p;
+	int n;
+	MetaBlock mb;
+
+	if(k->nindex == 0)
+		return;
+	assert(k->nindex <= k->maxindex);
+
+	p = k->buf;
+	n = k->rp - p;
+
+	mb.size = n;
+	mb.free = 0;
+	mb.nindex = k->nindex;
+	mb.maxindex = k->maxindex;
+	mb.buf = p;
+	mbPack(&mb);
+	
+	p += MetaHeaderSize;
+
+	/* XXX this is not reentrant! */
+	blockBase = k->buf;
+	qsort(p, k->nindex, MetaIndexSize, dirCmp);
+	p += k->nindex*MetaIndexSize;
+	
+	memset(p, 0, (k->maxindex-k->nindex)*MetaIndexSize);
+	p += (k->maxindex-k->nindex)*MetaIndexSize;
+
+	sinkWrite(k->sink, k->buf, n);
+
+	/* move down partial entry */
+	n = k->p - k->rp;
+	memmove(p, k->rp, n);
+	k->rp = p;
+	k->p = p + n;
+	k->nindex = 0;
+}
+
+void
+metaSinkPutc(MetaSink *k, int c)
+{
+	if(k->p+1 > k->ep)
+		metaSinkFlush(k);
+	if(k->p+1 > k->ep)
+		vtFatal("directory entry too large");
+	k->p[0] = c;
+	k->p++;
+}
+
+void
+metaSinkPutString(MetaSink *k, char *s)
+{
+	int n = strlen(s);
+	metaSinkPutc(k, n>>8);
+	metaSinkPutc(k, n);
+	metaSinkWrite(k, (uchar*)s, n);
+}
+
+void
+metaSinkPutUint32(MetaSink *k, ulong x)
+{
+	metaSinkPutc(k, x>>24);
+	metaSinkPutc(k, x>>16);
+	metaSinkPutc(k, x>>8);
+	metaSinkPutc(k, x);
+}
+
+void
+metaSinkPutUint64(MetaSink *k, uvlong x)
+{
+	metaSinkPutUint32(k, x>>32);
+	metaSinkPutUint32(k, x);
+}
+
+void
+metaSinkWrite(MetaSink *k, uchar *data, int n)
+{
+	if(k->p + n > k->ep)
+		metaSinkFlush(k);
+	if(k->p + n > k->ep)
+		vtFatal("directory entry too large");
+	
+	memmove(k->p, data, n);
+	k->p += n;
+}
+
+void
+metaSinkWriteDir(MetaSink *ms, VacDir *dir)
+{
+	metaSinkPutUint32(ms, DirMagic);
+	metaSinkPutc(ms, Version>>8);
+	metaSinkPutc(ms, Version);		
+	metaSinkPutString(ms, dir->elem);
+	metaSinkPutUint32(ms, dir->entry);
+	metaSinkPutUint64(ms, dir->qid);
+	metaSinkPutString(ms, dir->uid);
+	metaSinkPutString(ms, dir->gid);
+	metaSinkPutString(ms, dir->mid);
+	metaSinkPutUint32(ms, dir->mtime);
+	metaSinkPutUint32(ms, dir->mcount);
+	metaSinkPutUint32(ms, dir->ctime);
+	metaSinkPutUint32(ms, dir->atime);
+	metaSinkPutUint32(ms, dir->mode);
+
+	if(dir->plan9) {
+		metaSinkPutc(ms, DirPlan9Entry);	/* plan9 extra info */
+		metaSinkPutc(ms, 0);			/* plan9 extra size */
+		metaSinkPutc(ms, 12);			/* plan9 extra size */
+		metaSinkPutUint64(ms, dir->p9path);
+		metaSinkPutUint32(ms, dir->p9version);
+	}
+
+	if(dir->qidSpace != 0) {
+		metaSinkPutc(ms, DirQidSpaceEntry);
+		metaSinkPutc(ms, 0);
+		metaSinkPutc(ms, 16);
+		metaSinkPutUint64(ms, dir->qidOffset);
+		metaSinkPutUint64(ms, dir->qidMax);
+	}
+
+	if(dir->gen != 0) {
+		metaSinkPutc(ms, DirGenEntry);
+		metaSinkPutc(ms, 0);
+		metaSinkPutc(ms, 4);
+		metaSinkPutUint32(ms, dir->gen);
+	}
+
+	metaSinkEOR(ms);
+}
+
+
+void
+plan9ToVacDir(VacDir *vd, Dir *dir, ulong entry, uvlong qid)
+{
+	memset(vd, 0, sizeof(VacDir));
+
+	vd->elem = vtStrDup(dir->name);
+	vd->entry = entry;
+	vd->qid = qid;
+	vd->uid = vtStrDup(dir->uid);
+	vd->gid = vtStrDup(dir->gid);
+	vd->mid = vtStrDup(dir->muid);
+	vd->mtime = dir->mtime;
+	vd->mcount = 0;
+	vd->ctime = dir->mtime;		/* ctime: not available on plan 9 */
+	vd->atime = dir->atime;
+
+	vd->mode = dir->mode & 0777;
+	if(dir->mode & DMDIR)
+		vd->mode |= ModeDir;
+	if(dir->mode & DMAPPEND)
+		vd->mode |= ModeAppend;
+	if(dir->mode & DMEXCL)
+		vd->mode |= ModeExclusive;
+
+	vd->plan9 = 1;
+	vd->p9path = dir->qid.path;
+	vd->p9version = dir->qid.vers;
+}
+
+
+void
+metaSinkEOR(MetaSink *k)
+{
+	uchar *p;
+	int o, n;
+
+	p = k->buf + MetaHeaderSize;
+	p += k->nindex * MetaIndexSize;
+	o = k->rp-k->buf; 	/* offset from start of block */
+	n = k->p-k->rp;		/* size of entry */
+	p[0] = o >> 8;
+	p[1] = o;
+	p[2] = n >> 8;
+	p[3] = n;
+	k->rp = k->p;
+	k->nindex++;
+	if(k->nindex == k->maxindex)
+		metaSinkFlush(k);
+}
+
+void
+metaSinkClose(MetaSink *k)
+{
+	metaSinkFlush(k);
+	sinkClose(k->sink);
+}
+
+void
+metaSinkFree(MetaSink *k)
+{
+	sinkFree(k->sink);
+	vtMemFree(k->buf);
+	vtMemFree(k);
+}
+
+static void
+warn(char *fmt, ...)
+{
+	va_list arg;
+
+	va_start(arg, fmt);
+	fprint(2, "%s: ", argv0);
+	vfprint(2, fmt, arg);
+	fprint(2, "\n");
+	va_end(arg);
+}
+
+static void
+cleanup(void)
+{
+	if(oname != nil)
+		remove(oname);
+}
+
+#define TWID64	((u64int)~(u64int)0)
+
+static u64int
+unittoull(char *s)
+{
+	char *es;
+	u64int n;
+
+	if(s == nil)
+		return TWID64;
+	n = strtoul(s, &es, 0);
+	if(*es == 'k' || *es == 'K'){
+		n *= 1024;
+		es++;
+	}else if(*es == 'm' || *es == 'M'){
+		n *= 1024*1024;
+		es++;
+	}else if(*es == 'g' || *es == 'G'){
+		n *= 1024*1024*1024;
+		es++;
+	}
+	if(*es != '\0')
+		return TWID64;
+	return n;
+}
diff --git a/src/cmd/vac/vac.c b/src/cmd/vac/vac.c
new file mode 100644
index 0000000..8153c37
--- /dev/null
+++ b/src/cmd/vac/vac.c
@@ -0,0 +1,1024 @@
+#include <u.h>
+#include <libc.h>
+#include <venti.h>
+
+int bsize;
+char *host;
+VtConn *z;
+
+void
+usage(void)
+{
+	fprint(2, "usage: vac [-b blocksize] [-h host] file\n");
+}
+
+void
+main(int argc, char *argv[])
+{
+	ARGBEGIN{
+	default:
+		usage();
+	case 'b':
+		bsize = unittoull(EARGF(usage()));
+		break;
+	case 'h':
+		host = EARGF(usage());
+		break;
+	}ARGEND
+
+	if(bsize < 512)
+		bsize = 512;
+	if(bsize > VtMaxLumpSize)
+		bsize = VtMaxLumpSize;
+	maxbsize = bsize;
+
+	vtAttach();
+
+	fmtinstall('V', vtScoreFmt);
+	fmtinstall('R', vtErrFmt);
+
+	z = vtDial(host, 0);
+	if(z == nil)
+		vtFatal("could not connect to server: %R");
+
+	if(!vtConnect(z, 0))
+		vtFatal("vtConnect: %R");
+
+	qsort(exclude, nexclude, sizeof(char*), strpCmp);
+
+	vac(z, argv);
+	if(!vtSync(z))
+		fprint(2, "warning: could not ask server to flush pending writes: %R\n");
+
+	if(statsFlag)
+		fprint(2, "files %ld:%ld data %ld:%ld:%ld meta %ld\n", stats.file, stats.sfile,
+			stats.data, stats.skip, stats.sdata, stats.meta);
+//packetStats();
+	vtClose(z);
+	vtDetach();
+
+	exits(0);
+}
+
+static int
+vac(VtSession *z, char *argv[])
+{
+	DirSink *dsink, *ds;
+	MetaSink *ms;
+	VtRoot root;
+	uchar score[VtScoreSize], buf[VtRootSize];
+	char cwd[2048];
+	int cd, i;
+	char *cp2, *cp;
+	VacFS *fs;
+	VacFile *vff;
+	int fd;
+	Dir *dir;
+	VacDir vd;
+
+	if(getwd(cwd, sizeof(cwd)) == 0)
+		sysfatal("can't find current directory: %r\n");
+
+	dsink = dirSinkAlloc(z, bsize, bsize);
+
+	fs = nil;
+	if(dfile != nil) {
+		fs = vfsOpen(z, dfile, 1, 10000);
+		if(fs == nil)
+			fprint(2, "could not open diff: %s: %s\n", dfile, vtGetError());
+	}
+		
+
+	if(oname != nil) {
+		fd = create(oname, OWRITE, 0666);
+		if(fd < 0)
+			sysfatal("could not create file: %s: %r", oname);
+	} else 
+		fd = 1;
+
+	dir = dirfstat(fd);
+	if(dir == nil)
+		sysfatal("dirfstat failed: %r");
+
+	for(; *argv; argv++) {
+		cp2 = *argv;
+		cd = 0;
+		for (cp = *argv; *cp; cp++)
+			if (*cp == '/')
+				cp2 = cp;
+		if (cp2 != *argv) {
+			*cp2 = '\0';
+			chdir(*argv);
+			*cp2 = '/';
+			cp2++;
+			cd = 1;
+		}
+		vff = nil;
+		if(fs)
+			vff = vfOpen(fs, cp2);
+		vacFile(dsink, argv[0], cp2, vff);
+		if(vff)
+			vfDecRef(vff);
+		if(cd && chdir(cwd) < 0)
+			sysfatal("can't cd back to %s: %r\n", cwd);
+	}
+	
+	if(isi) {
+		vff = nil;
+		if(fs)
+			vff = vfOpen(fs, isi);
+		vacStdin(dsink, isi, vff);
+		if(vff)
+			vfDecRef(vff);
+	}
+
+	dirSinkClose(dsink);
+
+	/* build meta information for the root */
+	ms = metaSinkAlloc(z, bsize, bsize);
+	/* fake into a directory */
+	dir->mode |= (dir->mode&0444)>>2;
+	dir->qid.type |= QTDIR;
+	dir->mode |= DMDIR;
+	plan9ToVacDir(&vd, dir, 0, fileid++);
+	if(strcmp(vd.elem, "/") == 0){
+		vtMemFree(vd.elem);
+		vd.elem = vtStrDup("root");
+	}
+	metaSinkWriteDir(ms, &vd);
+	vdCleanup(&vd);
+	metaSinkClose(ms);
+	
+	ds = dirSinkAlloc(z, bsize, bsize);
+	dirSinkWriteSink(ds, dsink->sink);
+	dirSinkWriteSink(ds, dsink->msink->sink);
+	dirSinkWriteSink(ds, ms->sink);
+	dirSinkClose(ds);
+
+	memset(&root, 0, sizeof(root));		
+	root.version = VtRootVersion;
+	strncpy(root.name, dir->name, sizeof(root.name));
+	root.name[sizeof(root.name)-1] = 0;
+	free(dir);
+	sprint(root.type, "vac");
+	memmove(root.score, ds->sink->dir.score, VtScoreSize);
+	root.blockSize = maxbsize;
+	if(fs != nil)
+		vfsGetScore(fs, root.prev);
+
+	metaSinkFree(ms);
+	dirSinkFree(ds);
+	dirSinkFree(dsink);
+	if(fs != nil)
+		vfsClose(fs);
+	
+	vtRootPack(&root, buf);
+	if(!vacWrite(z, score, VtRootType, buf, VtRootSize))
+		vtFatal("vacWrite failed: %s", vtGetError());
+
+	fprint(fd, "vac:");
+	for(i=0; i<VtScoreSize; i++)
+		fprint(fd, "%.2x", score[i]);
+	fprint(fd, "\n");
+	
+	/* avoid remove at cleanup */
+	oname = nil;
+	return 1;
+}
+
+static int
+isExcluded(char *name)
+{
+	int bot, top, i, x;
+
+	bot = 0;	
+	top = nexclude;
+	while(bot < top) {
+		i = (bot+top)>>1;
+		x = strcmp(exclude[i], name);
+		if(x == 0)
+			return 1;
+		if(x < 0)
+			bot = i + 1;
+		else /* x > 0 */
+			top = i;
+	}
+	return 0;
+}
+
+static void
+vacFile(DirSink *dsink, char *lname, char *sname, VacFile *vf)
+{
+	int fd;
+	Dir *dir;
+	VacDir vd;
+	ulong entry;
+
+	if(isExcluded(lname)) {
+		warn("excluding: %s", lname);
+		return;
+	}
+
+	if(merge && vacMerge(dsink, lname, sname))
+		return;
+
+	fd = open(sname, OREAD);
+	if(fd < 0) {
+		warn("could not open file: %s: %s", lname, vtOSError());
+		return;
+	}
+
+	if(verbose)
+		fprint(2, "%s\n", lname);
+
+	dir = dirfstat(fd);
+	if(dir == nil) {
+		warn("can't stat %s: %r", lname);
+		close(fd);
+		return;
+	}
+
+	entry = dsink->nentry;
+
+	if(dir->mode & DMDIR) 
+		vacDir(dsink, fd, lname, sname, vf);
+	else
+		vacData(dsink, fd, lname, vf, dir);
+
+	plan9ToVacDir(&vd, dir, entry, fileid++);
+	metaSinkWriteDir(dsink->msink, &vd);
+	vdCleanup(&vd);
+
+	free(dir);
+	close(fd);
+}
+
+static void
+vacStdin(DirSink *dsink, char *name, VacFile *vf)
+{
+	Dir *dir;
+	VacDir vd;
+	ulong entry;
+
+	if(verbose)
+		fprint(2, "%s\n", "<stdio>");
+
+	dir = dirfstat(0);
+	if(dir == nil) {
+		warn("can't stat <stdio>: %r");
+		return;
+	}
+
+	entry = dsink->nentry;
+
+	vacData(dsink, 0, "<stdin>", vf, dir);
+
+	plan9ToVacDir(&vd, dir, entry, fileid++);
+	vd.elem = vtStrDup(name);
+	metaSinkWriteDir(dsink->msink, &vd);
+	vdCleanup(&vd);
+
+	free(dir);
+}
+
+static ulong
+vacDataSkip(Sink *sink, VacFile *vf, int fd, ulong blocks, uchar *buf, char *lname)
+{
+	int n;
+	ulong i;
+	uchar score[VtScoreSize];
+
+	/* skip blocks for append only files */
+	if(seek(fd, (blocks-1)*bsize, 0) != (blocks-1)*bsize) {
+		warn("error seeking: %s", lname);
+		goto Err;
+	}
+	n = readBlock(fd, buf, bsize);
+	if(n < bsize) {
+		warn("error checking append only file: %s", lname);
+		goto Err;
+	}
+	if(!vfGetBlockScore(vf, blocks-1, score) || !vtSha1Check(score, buf, n)) {
+		warn("last block of append file did not match: %s", lname);
+		goto Err;
+	}
+
+	for(i=0; i<blocks; i++) {
+		if(!vfGetBlockScore(vf, i, score)) {
+			warn("could not get score: %s: %lud", lname, i);
+			seek(fd, i*bsize, 0);
+			return i;
+		}
+		stats.skip++;
+		sinkWriteScore(sink, score, bsize);
+	}
+
+	return i;
+Err:
+	seek(fd, 0, 0);
+	return 0;
+}
+
+static void
+vacData(DirSink *dsink, int fd, char *lname, VacFile *vf, Dir *dir)
+{
+	uchar *buf;
+	Sink *sink;
+	int n;
+	uchar score[VtScoreSize];
+	ulong block, same;
+	VacDir vd;
+	ulong vfblocks;
+
+	vfblocks = 0;
+	if(vf != nil && qdiff) {
+		vfGetDir(vf, &vd);
+		if(vd.mtime == dir->mtime)
+		if(vd.size == dir->length)
+		if(!vd.plan9 || /* vd.p9path == dir->qid.path && */ vd.p9version == dir->qid.vers)
+		if(dirSinkWriteFile(dsink, vf)) {
+			stats.sfile++;
+			vdCleanup(&vd);
+			return;
+		}
+
+		/* look for an append only file */
+		if((dir->mode&DMAPPEND) != 0)
+		if(vd.size < dir->length)
+		if(vd.plan9)
+		if(vd.p9path == dir->qid.path)
+			vfblocks = vd.size/bsize;
+
+		vdCleanup(&vd);
+	}
+	stats.file++;
+
+	buf = vtMemAlloc(bsize);
+	sink = sinkAlloc(dsink->sink->z, bsize, bsize);
+	block = 0;
+	same = stats.sdata+stats.skip;
+
+	if(vfblocks > 1)
+		block += vacDataSkip(sink, vf, fd, vfblocks, buf, lname);
+
+if(0) fprint(2, "vacData: %s: %ld\n", lname, block);
+	for(;;) {
+		n = readBlock(fd, buf, bsize);
+		if(0 && n < 0)
+			warn("file truncated due to read error: %s: %s", lname, vtOSError());
+		if(n <= 0)
+			break;
+		if(vf != nil && vfGetBlockScore(vf, block, score) && vtSha1Check(score, buf, n)) {
+			stats.sdata++;
+			sinkWriteScore(sink, score, n);
+		} else
+			sinkWrite(sink, buf, n);
+		block++;
+	}
+	same = stats.sdata+stats.skip - same;
+
+	if(same && (dir->mode&DMAPPEND) != 0)
+		if(0)fprint(2, "%s: total %lud same %lud:%lud diff %lud\n",
+			lname, block, same, vfblocks, block-same);
+
+	sinkClose(sink);
+	dirSinkWriteSink(dsink, sink);
+	sinkFree(sink);
+	free(buf);
+}
+
+
+static void
+vacDir(DirSink *dsink, int fd, char *lname, char *sname, VacFile *vf)
+{
+	Dir *dirs;
+	char *ln, *sn;
+	int i, nd;
+	DirSink *ds;
+	VacFile *vvf;
+	char *name;
+
+	ds = dirSinkAlloc(dsink->sink->z, bsize, bsize);
+	while((nd = dirread(fd, &dirs)) > 0){
+		for(i = 0; i < nd; i++){
+			name = dirs[i].name;
+			/* check for bad file names */
+			if(name[0] == 0 || strcmp(name, ".") == 0 || strcmp(name, "..") == 0)
+				continue;
+			ln = vtMemAlloc(strlen(lname) + strlen(name) + 2);
+			sn = vtMemAlloc(strlen(sname) + strlen(name) + 2);
+			sprint(ln, "%s/%s", lname, name);
+			sprint(sn, "%s/%s", sname, name);
+			if(vf != nil)
+				vvf = vfWalk(vf, name);
+			else
+				vvf = nil;
+			vacFile(ds, ln, sn, vvf);
+			if(vvf != nil)
+				vfDecRef(vvf);
+			vtMemFree(ln);
+			vtMemFree(sn);
+		}
+		free(dirs);
+	}
+	dirSinkClose(ds);
+	dirSinkWriteSink(dsink, ds->sink);
+	dirSinkWriteSink(dsink, ds->msink->sink);
+	dirSinkFree(ds);
+}
+
+static int
+vacMergeFile(DirSink *dsink, VacFile *vf, VacDir *dir, uvlong offset, uvlong *max)
+{
+	uchar buf[VtEntrySize];
+	VtEntry dd, md;
+	int e;
+
+	if(vfRead(vf, buf, VtEntrySize, (uvlong)dir->entry*VtEntrySize) != VtEntrySize) {
+		warn("could not read venti dir entry: %s\n", dir->elem);
+		return 0;
+	}
+	vtEntryUnpack(&dd, buf, 0);
+
+	if(dir->mode & ModeDir)	{
+		e = dir->mentry;
+		if(e == 0)
+			e = dir->entry + 1;
+		
+		if(vfRead(vf, buf, VtEntrySize, e*VtEntrySize) != VtEntrySize) {
+			warn("could not read venti dir entry: %s\n", dir->elem);
+			return 0;
+		}
+		vtEntryUnpack(&md, buf, 0);
+	}
+
+	/* max might incorrect in some old dumps */
+	if(dir->qid >= *max) {
+		warn("qid out of range: %s", dir->elem);
+		*max = dir->qid;
+	}
+
+	dir->qid += offset;
+	dir->entry = dsink->nentry;
+
+	if(dir->qidSpace) {
+		dir->qidOffset += offset;
+	} else {
+		dir->qidSpace = 1;
+		dir->qidOffset = offset;
+		dir->qidMax = *max;
+	}
+
+	dirSinkWrite(dsink, &dd);
+	if(dir->mode & ModeDir)	
+		dirSinkWrite(dsink, &md);
+	metaSinkWriteDir(dsink->msink, dir);
+	
+	return 1;
+}
+
+static int
+vacMerge(DirSink *dsink, char *lname, char *sname)
+{
+	char *p;
+	VacFS *fs;
+	VacFile *vf;
+	VacDirEnum *d;
+	VacDir dir;
+	uvlong max;
+
+	p = strrchr(sname, '.');
+	if(p == 0 || strcmp(p, ".vac"))
+		return 0;
+
+	d = nil;
+	fs = vfsOpen(dsink->sink->z, sname, 1, 100);
+	if(fs == nil)
+		return 0;
+
+	vf = vfOpen(fs, "/");
+	if(vf == nil)
+		goto Done;
+	max = vfGetId(vf);
+	d = vdeOpen(fs, "/");
+	if(d == nil)
+		goto Done;
+
+	if(verbose)
+		fprint(2, "merging: %s\n", lname);
+
+	if(maxbsize < vfsGetBlockSize(fs))
+		maxbsize = vfsGetBlockSize(fs);
+
+	for(;;) {
+		if(vdeRead(d, &dir, 1) < 1)
+			break;
+		vacMergeFile(dsink, vf, &dir, fileid, &max);
+		vdCleanup(&dir);	
+	}
+	fileid += max;
+
+Done:
+	if(d != nil)
+		vdeFree(d);
+	if(vf != nil)
+		vfDecRef(vf);
+	vfsClose(fs);
+	return 1;
+}
+
+Sink *
+sinkAlloc(VtSession *z, int psize, int dsize)
+{
+	Sink *k;
+	int i;
+
+	if(psize < 512 || psize > VtMaxLumpSize)
+		vtFatal("sinkAlloc: bad psize");
+	if(dsize < 512 || dsize > VtMaxLumpSize)
+		vtFatal("sinkAlloc: bad psize");
+
+	psize = VtScoreSize*(psize/VtScoreSize);
+
+	k = vtMemAllocZ(sizeof(Sink));
+	k->z = z;
+	k->dir.flags = VtEntryActive;
+	k->dir.psize = psize;
+	k->dir.dsize = dsize;
+	k->buf = vtMemAllocZ(VtPointerDepth*k->dir.psize + VtScoreSize);
+	for(i=0; i<=VtPointerDepth; i++)
+		k->pbuf[i] = k->buf + i*k->dir.psize;
+	return k;
+}
+
+void
+sinkWriteScore(Sink *k, uchar score[VtScoreSize], int n)
+{
+	int i;
+	uchar *p;
+	VtEntry *d;
+
+	memmove(k->pbuf[0], score, VtScoreSize);
+
+	d = &k->dir;
+
+	for(i=0; i<VtPointerDepth; i++) {
+		k->pbuf[i] += VtScoreSize;
+		if(k->pbuf[i] < k->buf + d->psize*(i+1))
+			break;
+		if(i == VtPointerDepth-1)
+			vtFatal("file too big");
+		p = k->buf+i*d->psize;
+		stats.meta++;
+		if(!vacWrite(k->z, k->pbuf[i+1], VtPointerType0+i, p, d->psize))
+			vtFatal("vacWrite failed: %s", vtGetError());
+		k->pbuf[i] = p;
+	}
+
+	/* round size up to multiple of dsize */
+	d->size = d->dsize * ((d->size + d->dsize-1)/d->dsize);
+	
+	d->size += n;
+}
+
+void
+sinkWrite(Sink *k, uchar *p, int n)
+{
+	int type;
+	uchar score[VtScoreSize];
+
+	if(n > k->dir.dsize)
+		vtFatal("sinkWrite: size too big");
+
+	if(k->dir.flags & VtEntryDir) {
+		type = VtDirType;
+		stats.meta++;
+	} else {
+		type = VtDataType;
+		stats.data++;
+	}
+	if(!vacWrite(k->z, score, type, p, n))
+		vtFatal("vacWrite failed: %s", vtGetError());
+
+	sinkWriteScore(k, score, n);
+}
+
+static int
+sizeToDepth(uvlong s, int psize, int dsize)
+{
+	int np;
+	int d;
+	
+	/* determine pointer depth */
+	np = psize/VtScoreSize;
+	s = (s + dsize - 1)/dsize;
+	for(d = 0; s > 1; d++)
+		s = (s + np - 1)/np;
+	return d;
+}
+
+void
+sinkClose(Sink *k)
+{
+	int i, n;
+	uchar *p;
+	VtEntry *kd;
+
+	kd = &k->dir;
+
+	/* empty */
+	if(kd->size == 0) {
+		memmove(kd->score, vtZeroScore, VtScoreSize);
+		return;
+	}
+
+	for(n=VtPointerDepth-1; n>0; n--)
+		if(k->pbuf[n] > k->buf + kd->psize*n)
+			break;
+
+	kd->depth = sizeToDepth(kd->size, kd->psize, kd->dsize);
+
+	/* skip full part of tree */
+	for(i=0; i<n && k->pbuf[i] == k->buf + kd->psize*i; i++)
+		;
+
+	/* is the tree completely full */
+	if(i == n && k->pbuf[n] == k->buf + kd->psize*n + VtScoreSize) {
+		memmove(kd->score, k->pbuf[n] - VtScoreSize, VtScoreSize);
+		return;
+	}
+	n++;
+
+	/* clean up the edge */
+	for(; i<n; i++) {
+		p = k->buf+i*kd->psize;
+		stats.meta++;
+		if(!vacWrite(k->z, k->pbuf[i+1], VtPointerType0+i, p, k->pbuf[i]-p))
+			vtFatal("vacWrite failed: %s", vtGetError());
+		k->pbuf[i+1] += VtScoreSize;
+	}
+	memmove(kd->score, k->pbuf[i] - VtScoreSize, VtScoreSize);
+}
+
+void
+sinkFree(Sink *k)
+{
+	vtMemFree(k->buf);
+	vtMemFree(k);
+}
+
+DirSink *
+dirSinkAlloc(VtSession *z, int psize, int dsize)
+{
+	DirSink *k;
+	int ds;
+
+	ds = VtEntrySize*(dsize/VtEntrySize);
+
+	k = vtMemAllocZ(sizeof(DirSink));
+	k->sink = sinkAlloc(z, psize, ds);
+	k->sink->dir.flags |= VtEntryDir;
+	k->msink = metaSinkAlloc(z, psize, dsize);
+	k->buf = vtMemAlloc(ds);
+	k->p = k->buf;
+	k->ep = k->buf + ds;
+	return k;
+}
+
+void
+dirSinkWrite(DirSink *k, VtEntry *dir)
+{
+	if(k->p + VtEntrySize > k->ep) {
+		sinkWrite(k->sink, k->buf, k->p - k->buf);
+		k->p = k->buf;
+	}
+	vtEntryPack(dir, k->p, 0);
+	k->nentry++;
+	k->p += VtEntrySize;
+}
+
+void
+dirSinkWriteSink(DirSink *k, Sink *sink)
+{
+	dirSinkWrite(k, &sink->dir);
+}
+
+int
+dirSinkWriteFile(DirSink *k, VacFile *vf)
+{
+	VtEntry dir;
+
+	if(!vfGetVtEntry(vf, &dir))
+		return 0;
+	dirSinkWrite(k, &dir);
+	return 1;
+}
+
+void
+dirSinkClose(DirSink *k)
+{
+	metaSinkClose(k->msink);
+	if(k->p != k->buf)
+		sinkWrite(k->sink, k->buf, k->p - k->buf);
+	sinkClose(k->sink);
+}
+
+void
+dirSinkFree(DirSink *k)
+{
+	sinkFree(k->sink);
+	metaSinkFree(k->msink);
+	vtMemFree(k->buf);
+	vtMemFree(k);
+}
+
+MetaSink *
+metaSinkAlloc(VtSession *z, int psize, int dsize)
+{
+	MetaSink *k;
+
+	k = vtMemAllocZ(sizeof(MetaSink));
+	k->sink = sinkAlloc(z, psize, dsize);
+	k->buf = vtMemAlloc(dsize);
+	k->maxindex = dsize/100;	/* 100 byte entries seems reasonable */
+	if(k->maxindex < 1)
+		k->maxindex = 1;
+	k->rp = k->p = k->buf + MetaHeaderSize + k->maxindex*MetaIndexSize;
+	k->ep = k->buf + dsize;
+	return k;
+}
+
+/* hack to get base to compare routine - not reentrant */
+uchar *blockBase;
+
+int
+dirCmp(void *p0, void *p1)
+{
+	uchar *q0, *q1;
+	int n0, n1, r;
+
+	/* name is first element of entry */
+	q0 = p0;
+	q0 = blockBase + (q0[0]<<8) + q0[1];
+	n0 = (q0[6]<<8) + q0[7];
+	q0 += 8;
+
+	q1 = p1;
+	q1 = blockBase + (q1[0]<<8) + q1[1];
+	n1 = (q1[6]<<8) + q1[7];
+	q1 += 8;
+
+	if(n0 == n1)
+		return memcmp(q0, q1, n0);
+	else if (n0 < n1) {
+		r = memcmp(q0, q1, n0);
+		return (r==0)?1:r;
+	} else  {
+		r = memcmp(q0, q1, n1);
+		return (r==0)?-1:r;
+	}
+}
+
+void
+metaSinkFlush(MetaSink *k)
+{
+	uchar *p;
+	int n;
+	MetaBlock mb;
+
+	if(k->nindex == 0)
+		return;
+	assert(k->nindex <= k->maxindex);
+
+	p = k->buf;
+	n = k->rp - p;
+
+	mb.size = n;
+	mb.free = 0;
+	mb.nindex = k->nindex;
+	mb.maxindex = k->maxindex;
+	mb.buf = p;
+	mbPack(&mb);
+	
+	p += MetaHeaderSize;
+
+	/* XXX this is not reentrant! */
+	blockBase = k->buf;
+	qsort(p, k->nindex, MetaIndexSize, dirCmp);
+	p += k->nindex*MetaIndexSize;
+	
+	memset(p, 0, (k->maxindex-k->nindex)*MetaIndexSize);
+	p += (k->maxindex-k->nindex)*MetaIndexSize;
+
+	sinkWrite(k->sink, k->buf, n);
+
+	/* move down partial entry */
+	n = k->p - k->rp;
+	memmove(p, k->rp, n);
+	k->rp = p;
+	k->p = p + n;
+	k->nindex = 0;
+}
+
+void
+metaSinkPutc(MetaSink *k, int c)
+{
+	if(k->p+1 > k->ep)
+		metaSinkFlush(k);
+	if(k->p+1 > k->ep)
+		vtFatal("directory entry too large");
+	k->p[0] = c;
+	k->p++;
+}
+
+void
+metaSinkPutString(MetaSink *k, char *s)
+{
+	int n = strlen(s);
+	metaSinkPutc(k, n>>8);
+	metaSinkPutc(k, n);
+	metaSinkWrite(k, (uchar*)s, n);
+}
+
+void
+metaSinkPutUint32(MetaSink *k, ulong x)
+{
+	metaSinkPutc(k, x>>24);
+	metaSinkPutc(k, x>>16);
+	metaSinkPutc(k, x>>8);
+	metaSinkPutc(k, x);
+}
+
+void
+metaSinkPutUint64(MetaSink *k, uvlong x)
+{
+	metaSinkPutUint32(k, x>>32);
+	metaSinkPutUint32(k, x);
+}
+
+void
+metaSinkWrite(MetaSink *k, uchar *data, int n)
+{
+	if(k->p + n > k->ep)
+		metaSinkFlush(k);
+	if(k->p + n > k->ep)
+		vtFatal("directory entry too large");
+	
+	memmove(k->p, data, n);
+	k->p += n;
+}
+
+void
+metaSinkWriteDir(MetaSink *ms, VacDir *dir)
+{
+	metaSinkPutUint32(ms, DirMagic);
+	metaSinkPutc(ms, Version>>8);
+	metaSinkPutc(ms, Version);		
+	metaSinkPutString(ms, dir->elem);
+	metaSinkPutUint32(ms, dir->entry);
+	metaSinkPutUint64(ms, dir->qid);
+	metaSinkPutString(ms, dir->uid);
+	metaSinkPutString(ms, dir->gid);
+	metaSinkPutString(ms, dir->mid);
+	metaSinkPutUint32(ms, dir->mtime);
+	metaSinkPutUint32(ms, dir->mcount);
+	metaSinkPutUint32(ms, dir->ctime);
+	metaSinkPutUint32(ms, dir->atime);
+	metaSinkPutUint32(ms, dir->mode);
+
+	if(dir->plan9) {
+		metaSinkPutc(ms, DirPlan9Entry);	/* plan9 extra info */
+		metaSinkPutc(ms, 0);			/* plan9 extra size */
+		metaSinkPutc(ms, 12);			/* plan9 extra size */
+		metaSinkPutUint64(ms, dir->p9path);
+		metaSinkPutUint32(ms, dir->p9version);
+	}
+
+	if(dir->qidSpace != 0) {
+		metaSinkPutc(ms, DirQidSpaceEntry);
+		metaSinkPutc(ms, 0);
+		metaSinkPutc(ms, 16);
+		metaSinkPutUint64(ms, dir->qidOffset);
+		metaSinkPutUint64(ms, dir->qidMax);
+	}
+
+	if(dir->gen != 0) {
+		metaSinkPutc(ms, DirGenEntry);
+		metaSinkPutc(ms, 0);
+		metaSinkPutc(ms, 4);
+		metaSinkPutUint32(ms, dir->gen);
+	}
+
+	metaSinkEOR(ms);
+}
+
+
+void
+plan9ToVacDir(VacDir *vd, Dir *dir, ulong entry, uvlong qid)
+{
+	memset(vd, 0, sizeof(VacDir));
+
+	vd->elem = vtStrDup(dir->name);
+	vd->entry = entry;
+	vd->qid = qid;
+	vd->uid = vtStrDup(dir->uid);
+	vd->gid = vtStrDup(dir->gid);
+	vd->mid = vtStrDup(dir->muid);
+	vd->mtime = dir->mtime;
+	vd->mcount = 0;
+	vd->ctime = dir->mtime;		/* ctime: not available on plan 9 */
+	vd->atime = dir->atime;
+
+	vd->mode = dir->mode & 0777;
+	if(dir->mode & DMDIR)
+		vd->mode |= ModeDir;
+	if(dir->mode & DMAPPEND)
+		vd->mode |= ModeAppend;
+	if(dir->mode & DMEXCL)
+		vd->mode |= ModeExclusive;
+
+	vd->plan9 = 1;
+	vd->p9path = dir->qid.path;
+	vd->p9version = dir->qid.vers;
+}
+
+
+void
+metaSinkEOR(MetaSink *k)
+{
+	uchar *p;
+	int o, n;
+
+	p = k->buf + MetaHeaderSize;
+	p += k->nindex * MetaIndexSize;
+	o = k->rp-k->buf; 	/* offset from start of block */
+	n = k->p-k->rp;		/* size of entry */
+	p[0] = o >> 8;
+	p[1] = o;
+	p[2] = n >> 8;
+	p[3] = n;
+	k->rp = k->p;
+	k->nindex++;
+	if(k->nindex == k->maxindex)
+		metaSinkFlush(k);
+}
+
+void
+metaSinkClose(MetaSink *k)
+{
+	metaSinkFlush(k);
+	sinkClose(k->sink);
+}
+
+void
+metaSinkFree(MetaSink *k)
+{
+	sinkFree(k->sink);
+	vtMemFree(k->buf);
+	vtMemFree(k);
+}
+
+static void
+warn(char *fmt, ...)
+{
+	va_list arg;
+
+	va_start(arg, fmt);
+	fprint(2, "%s: ", argv0);
+	vfprint(2, fmt, arg);
+	fprint(2, "\n");
+	va_end(arg);
+}
+
+static void
+cleanup(void)
+{
+	if(oname != nil)
+		remove(oname);
+}
+
+#define TWID64	((u64int)~(u64int)0)
+
+static u64int
+unittoull(char *s)
+{
+	char *es;
+	u64int n;
+
+	if(s == nil)
+		return TWID64;
+	n = strtoul(s, &es, 0);
+	if(*es == 'k' || *es == 'K'){
+		n *= 1024;
+		es++;
+	}else if(*es == 'm' || *es == 'M'){
+		n *= 1024*1024;
+		es++;
+	}else if(*es == 'g' || *es == 'G'){
+		n *= 1024*1024*1024;
+		es++;
+	}
+	if(*es != '\0')
+		return TWID64;
+	return n;
+}
diff --git a/src/cmd/vac/vac.h b/src/cmd/vac/vac.h
new file mode 100644
index 0000000..549c441
--- /dev/null
+++ b/src/cmd/vac/vac.h
@@ -0,0 +1,126 @@
+typedef struct VacFS VacFS;
+typedef struct VacDir VacDir;
+typedef struct VacFile VacFile;
+typedef struct VacDirEnum VacDirEnum;
+
+/*
+ * Mode bits
+ */
+enum {
+	ModeOtherExec = (1<<0),		
+	ModeOtherWrite = (1<<1),
+	ModeOtherRead = (1<<2),
+	ModeGroupExec = (1<<3),
+	ModeGroupWrite = (1<<4),
+	ModeGroupRead = (1<<5),
+	ModeOwnerExec = (1<<6),
+	ModeOwnerWrite = (1<<7),
+	ModeOwnerRead = (1<<8),
+	ModeSticky = (1<<9),
+	ModeSetUid = (1<<10),
+	ModeSetGid = (1<<11),
+	ModeAppend = (1<<12),		/* append only file */
+	ModeExclusive = (1<<13),	/* lock file - plan 9 */
+	ModeLink = (1<<14),		/* sym link */
+	ModeDir	= (1<<15),		/* duplicate of DirEntry */
+	ModeHidden = (1<<16),		/* MS-DOS */
+	ModeSystem = (1<<17),		/* MS-DOS */
+	ModeArchive = (1<<18),		/* MS-DOS */
+	ModeTemporary = (1<<19),	/* MS-DOS */
+	ModeSnapshot = (1<<20),		/* read only snapshot */
+};
+
+enum {
+	MetaMagic = 0x5656fc79,
+	MetaHeaderSize = 12,
+	MetaIndexSize = 4,
+	IndexEntrySize = 8,
+	DirMagic = 0x1c4d9072,
+};
+
+enum {
+	DirPlan9Entry = 1,	/* not valid in version >= 9 */
+	DirNTEntry,		/* not valid in version >= 9 */
+	DirQidSpaceEntry,
+	DirGenEntry,		/* not valid in version >= 9 */
+};
+
+struct VacDir {
+	char *elem;		/* path element */
+	ulong entry;		/* entry in directory for data */
+	ulong gen;		/* generation of data entry */
+	ulong mentry;		/* entry in directory for meta */
+	ulong mgen;		/* generation of meta entry */
+	uvlong size;		/* size of file */
+	uvlong qid;		/* unique file id */
+	
+	char *uid;		/* owner id */
+	char *gid;		/* group id */
+	char *mid;		/* last modified by */
+	ulong mtime;		/* last modified time */
+	ulong mcount;		/* number of modifications: can wrap! */
+	ulong ctime;		/* directory entry last changed */
+	ulong atime;		/* last time accessed */
+	ulong mode;		/* various mode bits */
+
+	/* plan 9 */
+	int plan9;
+	uvlong p9path;
+	ulong p9version;
+
+	/* sub space of qid */
+	int qidSpace;
+	uvlong qidOffset;	/* qid offset */
+	uvlong qidMax;		/* qid maximum */
+};
+
+VacFS *vfsOpen(VtSession *z, char *file, int readOnly, long ncache);
+VacFS *vfsCreate(VtSession *z, int bsize, long ncache);
+int vfsGetBlockSize(VacFS*);
+int vfsIsReadOnly(VacFS*);
+VacFile *vfsGetRoot(VacFS*);
+
+long vfsGetCacheSize(VacFS*);
+int vfsSetCacheSize(VacFS*, long);
+int vfsSnapshot(VacFS*, char *src, char *dst);
+int vfsSync(VacFS*);
+int vfsClose(VacFS*);
+int vfsGetScore(VacFS*, uchar score[VtScoreSize]);
+
+/* 
+ * other ideas
+ *
+ * VacFS *vfsSnapshot(VacFS*, char *src);
+ * int vfsGraft(VacFS*, char *name, VacFS*);
+ */
+
+VacFile *vfOpen(VacFS*, char *path);
+VacFile *vfCreate(VacFile*, char *elem, ulong perm, char *user);
+VacFile *vfWalk(VacFile*, char *elem);
+int vfRemove(VacFile*, char*);
+int vfRead(VacFile*, void *, int n, vlong offset);
+int vfWrite(VacFile*, void *, int n, vlong offset, char *user);
+int vfReadPacket(VacFile*, Packet**, vlong offset);
+int vfWritePacket(VacFile*, Packet*, vlong offset, char *user);
+uvlong vfGetId(VacFile*);
+ulong vfGetMcount(VacFile*);
+int vfIsDir(VacFile*);
+int vfGetBlockScore(VacFile*, ulong bn, uchar score[VtScoreSize]);
+int vfGetSize(VacFile*, uvlong *size);
+int vfGetDir(VacFile*, VacDir*);
+int vfSetDir(VacFile*, VacDir*);
+int vfGetVtEntry(VacFile*, VtEntry*);
+VacFile *vfGetParent(VacFile*);
+int vfSync(VacFile*);
+VacFile *vfIncRef(VacFile*);
+void vfDecRef(VacFile*);
+VacDirEnum *vfDirEnum(VacFile*);
+int vfIsRoot(VacFile *vf);
+
+void	vdCleanup(VacDir *dir);
+void	vdCopy(VacDir *dst, VacDir *src);
+
+VacDirEnum *vdeOpen(VacFS*, char *path);
+int vdeRead(VacDirEnum*, VacDir *, int n);
+void vdeFree(VacDirEnum*);
+
diff --git a/src/cmd/vac/vacfs.c b/src/cmd/vac/vacfs.c
new file mode 100644
index 0000000..7702b0d
--- /dev/null
+++ b/src/cmd/vac/vacfs.c
@@ -0,0 +1,849 @@
+#include "stdinc.h"
+#include <auth.h>
+#include <fcall.h>
+#include "vac.h"
+
+typedef struct Fid Fid;
+typedef struct DirBuf DirBuf;
+
+enum
+{
+	OPERM	= 0x3,		/* mask of all permission types in open mode */
+};
+
+enum
+{
+	DirBufSize = 20,
+};
+
+struct Fid
+{
+	short busy;
+	short open;
+	int fid;
+	char *user;
+	Qid qid;
+	VacFile *file;
+
+	DirBuf *db;
+
+	Fid	*next;
+};
+
+struct DirBuf
+{
+	VacDirEnum *vde;
+	VacDir buf[DirBufSize];
+	int i, n;
+	int eof;
+};
+
+enum
+{
+	Pexec =		1,
+	Pwrite = 	2,
+	Pread = 	4,
+	Pother = 	1,
+	Pgroup = 	8,
+	Powner =	64,
+};
+
+Fid	*fids;
+uchar	*data;
+int	mfd[2];
+char	*user;
+uchar	mdata[8192+IOHDRSZ];
+int messagesize = sizeof mdata;
+Fcall	rhdr;
+Fcall	thdr;
+VacFS	*fs;
+VtSession *session;
+int	noperm;
+
+Fid *	newfid(int);
+void	error(char*);
+void	io(void);
+void	shutdown(void);
+void	usage(void);
+int	perm(Fid*, int);
+int	permf(VacFile*, char*, int);
+ulong	getl(void *p);
+void	init(char*, char*, long, int);
+DirBuf	*dirBufAlloc(VacFile*);
+VacDir	*dirBufGet(DirBuf*);
+int	dirBufUnget(DirBuf*);
+void	dirBufFree(DirBuf*);
+int	vacdirread(Fid *f, char *p, long off, long cnt);
+int	vdStat(VacDir *vd, uchar *p, int np);
+
+char	*rflush(Fid*), *rversion(Fid*),
+	*rauth(Fid*), *rattach(Fid*), *rwalk(Fid*),
+	*ropen(Fid*), *rcreate(Fid*),
+	*rread(Fid*), *rwrite(Fid*), *rclunk(Fid*),
+	*rremove(Fid*), *rstat(Fid*), *rwstat(Fid*);
+
+char 	*(*fcalls[])(Fid*) = {
+	[Tflush]	rflush,
+	[Tversion]	rversion,
+	[Tattach]	rattach,
+	[Tauth]		rauth,
+	[Twalk]		rwalk,
+	[Topen]		ropen,
+	[Tcreate]	rcreate,
+	[Tread]		rread,
+	[Twrite]	rwrite,
+	[Tclunk]	rclunk,
+	[Tremove]	rremove,
+	[Tstat]		rstat,
+	[Twstat]	rwstat,
+};
+
+char	Eperm[] =	"permission denied";
+char	Enotdir[] =	"not a directory";
+char	Enotexist[] =	"file does not exist";
+char	Einuse[] =	"file in use";
+char	Eexist[] =	"file exists";
+char	Enotowner[] =	"not owner";
+char	Eisopen[] = 	"file already open for I/O";
+char	Excl[] = 	"exclusive use file already open";
+char	Ename[] = 	"illegal name";
+char	Erdonly[] = 	"read only file system";
+char	Eio[] = 	"i/o error";
+char	Eempty[] = 	"directory is not empty";
+char	Emode[] =	"illegal mode";
+
+int dflag;
+
+void
+notifyf(void *a, char *s)
+{
+	USED(a);
+	if(strncmp(s, "interrupt", 9) == 0)
+		noted(NCONT);
+	noted(NDFLT);
+}
+
+void
+main(int argc, char *argv[])
+{
+	char *defmnt;
+	int p[2];
+	char buf[12];
+	int fd;
+	int stdio = 0;
+	char *host = nil;
+	long ncache = 1000;
+	int readOnly = 1;
+
+	defmnt = "/n/vac";
+	ARGBEGIN{
+	case 'd':
+		fmtinstall('F', fcallfmt);
+		dflag = 1;
+		break;
+	case 'c':
+		ncache = atoi(ARGF());
+		break;
+	case 'i':
+		defmnt = 0;
+		stdio = 1;
+		mfd[0] = 0;
+		mfd[1] = 1;
+		break;
+	case 'h':
+		host = ARGF();
+		break;
+	case 's':
+		defmnt = 0;
+		break;
+	case 'p':
+		noperm = 1;
+		break;
+	case 'm':
+		defmnt = ARGF();
+		break;
+	default:
+		usage();
+	}ARGEND
+
+	if(argc != 1)
+		usage();
+
+	vtAttach();
+
+	init(argv[0], host, ncache, readOnly);
+
+	if(pipe(p) < 0)
+		sysfatal("pipe failed: %r");
+	if(!stdio){
+		mfd[0] = p[0];
+		mfd[1] = p[0];
+		if(defmnt == 0){
+			fd = create("#s/vacfs", OWRITE, 0666);
+			if(fd < 0)
+				sysfatal("create of /srv/vacfs failed: %r");
+			sprint(buf, "%d", p[1]);
+			if(write(fd, buf, strlen(buf)) < 0)
+				sysfatal("writing /srv/vacfs: %r");
+		}
+	}
+
+	switch(rfork(RFFDG|RFPROC|RFNAMEG|RFNOTEG)){
+	case -1:
+		sysfatal("fork: %r");
+	case 0:
+		vtAttach();
+		close(p[1]);
+		io();
+		shutdown();
+		break;
+	default:
+		close(p[0]);	/* don't deadlock if child fails */
+		if(defmnt && mount(p[1], -1, defmnt, MREPL|MCREATE, "") < 0)
+			sysfatal("mount failed: %r");
+	}
+	vtDetach();
+	exits(0);
+}
+
+void
+usage(void)
+{
+	fprint(2, "usage: %s [-sd] [-h host] [-c ncache] [-m mountpoint] vacfile\n", argv0);
+	exits("usage");
+}
+
+char*
+rversion(Fid *unused)
+{
+	Fid *f;
+
+	USED(unused);
+
+	for(f = fids; f; f = f->next)
+		if(f->busy)
+			rclunk(f);
+
+	if(rhdr.msize < 256)
+		return "version: message size too small";
+	messagesize = rhdr.msize;
+	if(messagesize > sizeof mdata)
+		messagesize = sizeof mdata;
+	thdr.msize = messagesize;
+	if(strncmp(rhdr.version, "9P2000", 6) != 0)
+		return "unrecognized 9P version";
+	thdr.version = "9P2000";
+	return nil;
+}
+
+char*
+rflush(Fid *f)
+{
+	USED(f);
+	return 0;
+}
+
+char*
+rauth(Fid *f)
+{
+	USED(f);
+	return "vacfs: authentication not required";
+}
+
+char*
+rattach(Fid *f)
+{
+	/* no authentication for the momment */
+	VacFile *file;
+
+	file = vfsGetRoot(fs);
+	if(file == nil)
+		return vtGetError();
+	f->busy = 1;
+	f->file = file;
+	f->qid = (Qid){vfGetId(f->file), 0, QTDIR};
+	thdr.qid = f->qid;
+	if(rhdr.uname[0])
+		f->user = vtStrDup(rhdr.uname);
+	else
+		f->user = "none";
+	return 0;
+}
+
+VacFile*
+_vfWalk(VacFile *file, char *name)
+{
+	VacFile *n;
+
+	n = vfWalk(file, name);
+	if(n)
+		return n;
+	if(strcmp(name, "SLASH") == 0)
+		return vfWalk(file, "/");
+	return nil;
+}
+
+char*
+rwalk(Fid *f)
+{
+	VacFile *file, *nfile;
+	Fid *nf;
+	int nqid, nwname;
+	Qid qid;
+
+	if(f->busy == 0)
+		return Enotexist;
+	nf = nil;
+	if(rhdr.fid != rhdr.newfid){
+		if(f->open)
+			return Eisopen;
+		if(f->busy == 0)
+			return Enotexist;
+		nf = newfid(rhdr.newfid);
+		if(nf->busy)
+			return Eisopen;
+		nf->busy = 1;
+		nf->open = 0;
+		nf->qid = f->qid;
+		nf->file = vfIncRef(f->file);
+		nf->user = vtStrDup(f->user);
+		f = nf;
+	}
+
+	nwname = rhdr.nwname;
+
+	/* easy case */
+	if(nwname == 0) {
+		thdr.nwqid = 0;
+		return 0;
+	}
+
+	file = f->file;
+	vfIncRef(file);
+	qid = f->qid;
+
+	for(nqid = 0; nqid < nwname; nqid++){
+		if((qid.type & QTDIR) == 0){
+			vtSetError(Enotdir);
+			break;
+		}
+		if(!permf(file, f->user, Pexec)) {
+			vtSetError(Eperm);
+			break;
+		}
+		nfile = _vfWalk(file, rhdr.wname[nqid]);
+		if(nfile == nil)
+			break;
+		vfDecRef(file);
+		file = nfile;
+		qid.type = QTFILE;
+		if(vfIsDir(file))
+			qid.type = QTDIR;
+		qid.vers = vfGetMcount(file);
+		qid.path = vfGetId(file);
+		thdr.wqid[nqid] = qid;
+	}
+
+	thdr.nwqid = nqid;
+
+	if(nqid == nwname){
+		/* success */
+		f->qid = thdr.wqid[nqid-1];
+		vfDecRef(f->file);
+		f->file = file;
+		return 0;
+	}
+
+	vfDecRef(file);
+	if(nf != nil)
+		rclunk(nf);
+
+	/* only error on the first element */
+	if(nqid == 0)
+		return vtGetError();
+
+	return 0;
+}
+
+char *
+ropen(Fid *f)
+{
+	int mode, trunc;
+
+	if(f->open)
+		return Eisopen;
+	if(!f->busy)
+		return Enotexist;
+	mode = rhdr.mode;
+	thdr.iounit = messagesize - IOHDRSZ;
+	if(f->qid.type & QTDIR){
+		if(mode != OREAD)
+			return Eperm;
+		if(!perm(f, Pread))
+			return Eperm;
+		thdr.qid = f->qid;
+		f->db = nil;
+		f->open = 1;
+		return 0;
+	}
+	if(mode & ORCLOSE)
+		return Erdonly;
+	trunc = mode & OTRUNC;
+	mode &= OPERM;
+	if(mode==OWRITE || mode==ORDWR || trunc)
+		if(!perm(f, Pwrite))
+			return Eperm;
+	if(mode==OREAD || mode==ORDWR)
+		if(!perm(f, Pread))
+			return Eperm;
+	if(mode==OEXEC)
+		if(!perm(f, Pexec))
+			return Eperm;
+	thdr.qid = f->qid;
+	thdr.iounit = messagesize - IOHDRSZ;
+	f->open = 1;
+	return 0;
+}
+
+char*
+rcreate(Fid* fid)
+{
+	VacFile *vf;
+	ulong mode;
+
+	if(fid->open)
+		return Eisopen;
+	if(!fid->busy)
+		return Enotexist;
+	if(vfsIsReadOnly(fs))
+		return Erdonly;
+	vf = fid->file;
+	if(!vfIsDir(vf))
+		return Enotdir;
+	if(!permf(vf, fid->user, Pwrite))
+		return Eperm;
+
+	mode = rhdr.perm & 0777;
+
+	if(rhdr.perm & DMDIR){
+		if((rhdr.mode & OTRUNC) || (rhdr.perm & DMAPPEND))
+			return Emode;
+		switch(rhdr.mode & OPERM){
+		default:
+			return Emode;
+		case OEXEC:
+		case OREAD:
+			break;
+		case OWRITE:
+		case ORDWR:
+			return Eperm;
+		}
+		mode |= ModeDir;
+	}
+	vf = vfCreate(vf, rhdr.name, mode, "none");
+	if(vf == nil)
+		return vtGetError();
+	vfDecRef(fid->file);
+
+	fid->file = vf;
+	fid->qid.type = QTFILE;
+	if(vfIsDir(vf))
+		fid->qid.type = QTDIR;
+	fid->qid.vers = vfGetMcount(vf);
+	fid->qid.path = vfGetId(vf);
+
+	thdr.qid = fid->qid;
+	thdr.iounit = messagesize - IOHDRSZ;
+
+	return 0;
+}
+
+char*
+rread(Fid *f)
+{
+	char *buf;
+	vlong off;
+	int cnt;
+	VacFile *vf;
+	char *err;
+	int n;
+
+	if(!f->busy)
+		return Enotexist;
+	vf = f->file;
+	thdr.count = 0;
+	off = rhdr.offset;
+	buf = thdr.data;
+	cnt = rhdr.count;
+	if(f->qid.type & QTDIR)
+		n = vacdirread(f, buf, off, cnt);
+	else
+		n = vfRead(vf, buf, cnt, off);
+	if(n < 0) {
+		err = vtGetError();
+		if(err == nil)
+			err = "unknown error!";
+		return err;
+	}
+	thdr.count = n;
+	return 0;
+}
+
+char*
+rwrite(Fid *f)
+{
+	char *buf;
+	vlong off;
+	int cnt;
+	VacFile *vf;
+
+	if(!f->busy)
+		return Enotexist;
+	vf = f->file;
+	thdr.count = 0;
+	off = rhdr.offset;
+	buf = rhdr.data;
+	cnt = rhdr.count;
+	if(f->qid.type & QTDIR)
+		return "file is a directory";
+	thdr.count = vfWrite(vf, buf, cnt, off, "none");
+	if(thdr.count < 0) {
+fprint(2, "write failed: %s\n", vtGetError());
+		return vtGetError();
+	}
+	return 0;
+}
+
+char *
+rclunk(Fid *f)
+{
+	f->busy = 0;
+	f->open = 0;
+	vtMemFree(f->user);
+	f->user = nil;
+	vfDecRef(f->file);
+	f->file = nil;
+	dirBufFree(f->db);
+	f->db = nil;
+	return 0;
+}
+
+char *
+rremove(Fid *f)
+{
+	VacFile *vf, *vfp;
+	char *err = nil;
+
+	if(!f->busy)
+		return Enotexist;
+	vf = f->file;
+	vfp = vfGetParent(vf);
+
+	if(!permf(vfp, f->user, Pwrite)) {
+		err = Eperm;
+		goto Exit;
+	}
+
+	if(!vfRemove(vf, "none")) {
+print("vfRemove failed\n");
+		err = vtGetError();
+	}
+
+Exit:
+	vfDecRef(vfp);
+	rclunk(f);
+	return err;
+}
+
+char *
+rstat(Fid *f)
+{
+	VacDir dir;
+	static uchar statbuf[1024];
+
+	if(!f->busy)
+		return Enotexist;
+	vfGetDir(f->file, &dir);
+	thdr.stat = statbuf;
+	thdr.nstat = vdStat(&dir, thdr.stat, sizeof statbuf);
+	vdCleanup(&dir);
+	return 0;
+}
+
+char *
+rwstat(Fid *f)
+{
+	if(!f->busy)
+		return Enotexist;
+	return Erdonly;
+}
+
+int
+vdStat(VacDir *vd, uchar *p, int np)
+{
+	Dir dir;
+
+	memset(&dir, 0, sizeof(dir));
+
+	/*
+	 * Where do path and version come from
+	 */
+	dir.qid.path = vd->qid;
+	dir.qid.vers = vd->mcount;
+	dir.mode = vd->mode & 0777;
+	if(vd->mode & ModeAppend){
+		dir.qid.type |= QTAPPEND;
+		dir.mode |= DMAPPEND;
+	}
+	if(vd->mode & ModeExclusive){
+		dir.qid.type |= QTEXCL;
+		dir.mode |= DMEXCL;
+	}
+	if(vd->mode & ModeDir){
+		dir.qid.type |= QTDIR;
+		dir.mode |= DMDIR;
+	}
+
+	dir.atime = vd->atime;
+	dir.mtime = vd->mtime;
+	dir.length = vd->size;
+
+	dir.name = vd->elem;
+	dir.uid = vd->uid;
+	dir.gid = vd->gid;
+	dir.muid = vd->mid;
+
+	return convD2M(&dir, p, np);
+}
+
+DirBuf*
+dirBufAlloc(VacFile *vf)
+{
+	DirBuf *db;
+
+	db = vtMemAllocZ(sizeof(DirBuf));
+	db->vde = vfDirEnum(vf);
+	return db;
+}
+
+VacDir *
+dirBufGet(DirBuf *db)
+{
+	VacDir *vd;
+	int n;
+
+	if(db->eof)
+		return nil;
+
+	if(db->i >= db->n) {
+		n = vdeRead(db->vde, db->buf, DirBufSize);
+		if(n < 0)
+			return nil;
+		db->i = 0;
+		db->n = n;
+		if(n == 0) {
+			db->eof = 1;
+			return nil;
+		}
+	}
+
+	vd = db->buf + db->i;
+	db->i++;
+
+	return vd;
+}
+
+int
+dirBufUnget(DirBuf *db)
+{
+	assert(db->i > 0);
+	db->i--;
+	return 1;
+}
+
+void
+dirBufFree(DirBuf *db)
+{
+	int i;
+
+	if(db == nil)
+		return;
+
+	for(i=db->i; i<db->n; i++)
+		vdCleanup(db->buf + i);
+	vdeFree(db->vde);
+	vtMemFree(db);
+}
+
+int
+vacdirread(Fid *f, char *p, long off, long cnt)
+{
+	int n, nb;
+	VacDir *vd;
+
+	/*
+	 * special case of rewinding a directory
+	 * otherwise ignore the offset
+	 */
+	if(off == 0 && f->db) {
+		dirBufFree(f->db);
+		f->db = nil;
+	}
+
+	if(f->db == nil)
+		f->db = dirBufAlloc(f->file);
+
+	for(nb = 0; nb < cnt; nb += n) {
+		vd = dirBufGet(f->db);
+		if(vd == nil) {
+			if(!f->db->eof)
+				return -1;
+			break;
+		}
+		n = vdStat(vd, (uchar*)p, cnt-nb);
+		if(n <= BIT16SZ) {
+			dirBufUnget(f->db);
+			break;
+		}
+		vdCleanup(vd);
+		p += n;
+	}
+	return nb;
+}
+
+Fid *
+newfid(int fid)
+{
+	Fid *f, *ff;
+
+	ff = 0;
+	for(f = fids; f; f = f->next)
+		if(f->fid == fid)
+			return f;
+		else if(!ff && !f->busy)
+			ff = f;
+	if(ff){
+		ff->fid = fid;
+		return ff;
+	}
+	f = vtMemAllocZ(sizeof *f);
+	f->fid = fid;
+	f->next = fids;
+	fids = f;
+	return f;
+}
+
+void
+io(void)
+{
+	char *err;
+	int n;
+
+	for(;;){
+		/*
+		 * reading from a pipe or a network device
+		 * will give an error after a few eof reads
+		 * however, we cannot tell the difference
+		 * between a zero-length read and an interrupt
+		 * on the processes writing to us,
+		 * so we wait for the error
+		 */
+		n = read9pmsg(mfd[0], mdata, sizeof mdata);
+		if(n == 0)
+			continue;
+		if(n < 0)
+			break;
+		if(convM2S(mdata, n, &rhdr) != n)
+			sysfatal("convM2S conversion error");
+
+		if(dflag)
+			fprint(2, "vacfs:<-%F\n", &rhdr);
+
+		thdr.data = (char*)mdata + IOHDRSZ;
+		if(!fcalls[rhdr.type])
+			err = "bad fcall type";
+		else
+			err = (*fcalls[rhdr.type])(newfid(rhdr.fid));
+		if(err){
+			thdr.type = Rerror;
+			thdr.ename = err;
+		}else{
+			thdr.type = rhdr.type + 1;
+			thdr.fid = rhdr.fid;
+		}
+		thdr.tag = rhdr.tag;
+		if(dflag)
+			fprint(2, "vacfs:->%F\n", &thdr);
+		n = convS2M(&thdr, mdata, messagesize);
+		if(write(mfd[1], mdata, n) != n)
+			sysfatal("mount write: %r");
+	}
+}
+
+int
+permf(VacFile *vf, char *user, int p)
+{
+	VacDir dir;
+	ulong perm;
+
+	if(!vfGetDir(vf, &dir))
+		return 0;
+	perm = dir.mode & 0777;
+	if(noperm)
+		goto Good;
+	if((p*Pother) & perm)
+		goto Good;
+	if(strcmp(user, dir.gid)==0 && ((p*Pgroup) & perm))
+		goto Good;
+	if(strcmp(user, dir.uid)==0 && ((p*Powner) & perm))
+		goto Good;
+	vdCleanup(&dir);
+	return 0;
+Good:
+	vdCleanup(&dir);
+	return 1;
+}
+
+int
+perm(Fid *f, int p)
+{
+	return permf(f->file, f->user, p);
+}
+
+void
+init(char *file, char *host, long ncache, int readOnly)
+{
+	notify(notifyf);
+	user = getuser();
+
+	fmtinstall('V', vtScoreFmt);
+	fmtinstall('R', vtErrFmt);
+
+	session = vtDial(host, 0);
+	if(session == nil)
+		vtFatal("could not connect to server: %s", vtGetError());
+
+	if(!vtConnect(session, 0))
+		vtFatal("vtConnect: %s", vtGetError());
+
+	fs = vfsOpen(session, file, readOnly, ncache);
+	if(fs == nil)
+		vtFatal("vfsOpen: %s", vtGetError());
+}
+
+void
+shutdown(void)
+{
+	Fid *f;
+
+	for(f = fids; f; f = f->next) {
+		if(!f->busy)
+			continue;
+fprint(2, "open fid: %d\n", f->fid);
+		rclunk(f);
+	}
+
+	vfsClose(fs);
+	vtClose(session);
+}
+
diff --git a/src/cmd/vac/vactest.c b/src/cmd/vac/vactest.c
new file mode 100644
index 0000000..c456604
--- /dev/null
+++ b/src/cmd/vac/vactest.c
@@ -0,0 +1,182 @@
+#include "stdinc.h"
+#include "vac.h"
+#include "dat.h"
+#include "fns.h"
+
+void usage(void);
+int unvac(VacFS *fs);
+int readScore(int fd, uchar score[VtScoreSize]);
+static void warn(char *fmt, ...);
+void dirlist(VacFS *fs, char *path);
+
+static	int	nwant;
+static	char	**want;
+static	int	dflag = 1;
+static	int	cflag;
+static	int	lower;
+static	int	verbose;
+static	int	settimes;
+
+void
+main(int argc, char *argv[])
+{
+	char *zfile;
+	int ok, table;
+	VtSession *z;
+	char *vsrv = nil;
+	char *host = nil;
+	char *p;
+	int ncache = 1000;
+	VacFS *fs;
+
+	table = 0;
+	zfile = nil;
+	ARGBEGIN{
+	case 'D':
+		dflag++;
+		break;
+	case 'c':
+		cflag++;
+		break;
+	case 'C':
+		p = ARGF();
+		if(p == nil)
+			usage();
+		ncache = atoi(p);
+		if(ncache < 10)
+			ncache = 10;
+		if(ncache > 1000000)
+			ncache = 1000000;
+		break;
+	case 'i':
+		lower++;
+		break;
+	case 'f':
+		zfile = ARGF();
+		if(zfile == nil)
+			usage();
+		break;
+	case 'h':
+		host = ARGF();
+		break;
+	case 't':
+		table++;
+		break;
+	case 'T':
+		settimes++;
+		break;
+	case 's':
+		vsrv = ARGF();
+		break;
+	case 'v':
+		verbose++;
+		break;
+	default:
+		usage();
+		break;
+	}ARGEND
+
+	nwant = argc;
+	want = argv;
+
+	vtAttach();
+
+	if(zfile == nil)
+		usage();
+
+	if(vsrv != nil)
+		z = vtStdioServer(vsrv);
+	else
+		z = vtDial(host);
+	if(z == nil)
+		vtFatal("could not connect to server: %s", vtGetError());
+	vtSetDebug(z, 0);
+	if(!vtConnect(z, 0))
+		vtFatal("vtConnect: %s", vtGetError());
+	fs = vfsOpen(z, zfile, 1, ncache);
+	if(fs == nil)
+		vtFatal("vfsOpen: %s", vtGetError());
+	ok = unvac(fs);
+	vtClose(z);
+	vtDetach();
+	
+	exits(ok? 0 : "error");
+}
+
+void
+usage(void)
+{
+	fprint(2, "usage: %s [-tTcDv] -f zipfile [-s ventid] [-h host] [file ...]\n", argv0);
+	exits("usage");
+}
+
+void
+suck(VacFile *f)
+{
+	USED(f);
+}
+
+
+void
+vacfile(VacFS *fs, char *path, VacDir *vd)
+{
+	char *path2;
+
+	path2 = vtMemAlloc(strlen(path) + 1 + strlen(vd->elem) + 1);
+	if(path[1] == 0)
+		sprintf(path2, "/%s", vd->elem);
+	else
+		sprintf(path2, "%s/%s", path, vd->elem);
+fprint(2, "vac file: %s\n", path2);
+	if(vd->mode & ModeDir)
+		dirlist(fs, path2);
+	vtMemFree(path2);
+}
+
+void
+dirlist(VacFS *fs, char *path)
+{
+	VacDir vd[50];
+	VacDirEnum *ds;
+	int i, n;
+
+	ds = vdeOpen(fs, path);
+	if(ds == nil) {
+		fprint(2, "could not open: %s: %s\n", path, vtGetError());
+		return;
+	}
+	for(;;) {
+		n = vdeRead(ds, vd, sizeof(vd)/sizeof(VacDir));
+		if(n < 0) {
+			warn("vdRead failed: %s: %s", path, vtGetError());
+			return;
+		}
+		if(n == 0)
+			break;
+		for(i=0; i<n; i++) {
+			vacfile(fs, path, &vd[i]);
+			vdCleanup(&vd[i]);
+		}
+	}
+	vdeFree(ds);
+}
+
+int
+unvac(VacFS *fs)
+{
+	dirlist(fs, "/");
+
+	return 1;
+}
+
+static void
+warn(char *fmt, ...)
+{
+	va_list arg;
+
+	va_start(arg, fmt);
+	fprint(2, "%s: ", argv0);
+	vfprint(2, fmt, arg);
+	fprint(2, "\n");
+	va_end(arg);
+}
diff --git a/src/cmd/vac/vtdump.c b/src/cmd/vac/vtdump.c
new file mode 100644
index 0000000..963e468
--- /dev/null
+++ b/src/cmd/vac/vtdump.c
@@ -0,0 +1,391 @@
+#include "stdinc.h"
+#include <bio.h>
+
+typedef struct Source Source;
+
+struct Source
+{
+	ulong gen;
+	int psize;
+	int dsize;
+	int dir;
+	int active;
+	int depth;
+	uvlong size;
+	uchar score[VtScoreSize];
+	int reserved;
+};
+
+int bsize;
+Biobuf *bout;
+VtRoot root;
+int ver;
+int cmp;
+int all;
+int find;
+uchar fscore[VtScoreSize];
+VtSession *z;
+
+int vtGetUint16(uchar *p);
+ulong vtGetUint32(uchar *p);
+uvlong vtGetUint48(uchar *p);
+void usage(void);
+int parseScore(uchar *score, char *buf, int n);
+void readRoot(VtRoot*, uchar *score, char *file);
+int dumpDir(Source*, int indent);
+
+void
+main(int argc, char *argv[])
+{
+	char *host = nil;
+	uchar score[VtScoreSize];
+	Source source;
+	uchar buf[VtMaxLumpSize];
+	char *p;
+	int n;
+
+	ARGBEGIN{
+	case 'h':
+		host = ARGF();
+		break;
+	case 'c':
+		cmp++;
+		break;
+	case 'f':
+		find++;
+		p = ARGF();
+		if(p == nil || !parseScore(fscore, p, strlen(p)))
+			usage();
+		break;
+	case 'a':
+		all = 1;
+		break;
+	}ARGEND
+
+	vtAttach();
+
+	bout = vtMemAllocZ(sizeof(Biobuf));
+	Binit(bout, 1, OWRITE);
+
+	if(argc > 1)
+		usage();
+
+	vtAttach();
+
+	fmtinstall('V', vtScoreFmt);
+	fmtinstall('R', vtErrFmt);
+
+	z = vtDial(host, 0);
+	if(z == nil)
+		vtFatal("could not connect to server: %s", vtGetError());
+
+	if(!vtConnect(z, 0))
+		sysfatal("vtConnect: %r");
+
+	readRoot(&root, score, argv[0]);
+	ver = root.version;
+	bsize = root.blockSize;
+	if(!find) {
+		Bprint(bout, "score: %V\n", score);
+		Bprint(bout, "version: %d\n", ver);
+		Bprint(bout, "name: %s\n", root.name);
+		Bprint(bout, "type: %s\n", root.type);
+		Bprint(bout, "bsize: %d\n", bsize);
+		Bprint(bout, "prev: %V\n", root.prev);
+	}
+
+	switch(ver) {
+	default:
+		sysfatal("unknown version");
+	case VtRootVersion:
+		break;
+	}
+
+	n = vtRead(z, root.score, VtDirType, buf, bsize);
+	if(n < 0)
+		sysfatal("could not read root dir");
+
+	/* fake up top level source */
+	memset(&source, 0, sizeof(source));
+	memmove(source.score, root.score, VtScoreSize);
+	source.psize = bsize;
+	source.dsize = bsize;
+	source.dir = 1;
+	source.active = 1;
+	source.depth = 0;
+	source.size = n;
+
+	dumpDir(&source, 0);
+
+	Bterm(bout);
+
+	vtClose(z);
+	vtDetach();
+	exits(0);
+}
+
+void
+sourcePrint(Source *s, int indent, int entry)
+{
+	int i;
+	uvlong size;
+	int ne;
+
+	for(i=0; i<indent; i++)
+		Bprint(bout, " ");
+	Bprint(bout, "%4d", entry);
+	if(s->active) {
+		/* dir size in directory entries */
+		if(s->dir) {
+			ne = s->dsize/VtEntrySize;
+			size = ne*(s->size/s->dsize) + (s->size%s->dsize)/VtEntrySize;
+		} else 
+			size = s->size;
+		if(cmp) {
+			Bprint(bout, ": gen: %lud size: %llud",
+				s->gen, size);
+			if(!s->dir)
+				Bprint(bout, ": %V", s->score);
+		} else {
+			Bprint(bout, ": gen: %lud psize: %d dsize: %d",
+				s->gen, s->psize, s->dsize);
+			Bprint(bout, " depth: %d size: %llud: %V",
+				s->depth, size, s->score);
+		}
+		
+		if(s->reserved)
+			Bprint(bout, ": reserved not emtpy");
+	}
+	Bprint(bout, "\n");
+}
+
+int
+parse(Source *s, uchar *p)
+{
+	VtEntry dir;
+
+	memset(s, 0, sizeof(*s));
+	if(!vtEntryUnpack(&dir, p, 0))
+		return 0;
+
+	if(!(dir.flags & VtEntryActive))
+		return 1;
+
+	s->active = 1;
+	s->gen = dir.gen;
+	s->psize = dir.psize;
+	s->dsize = dir.size;
+	s->size = dir.size;
+	memmove(s->score, dir.score, VtScoreSize);
+	if(dir.flags & VtEntryDir)
+		s->dir = 1;
+	s->depth = dir.depth;
+	return 1;
+
+}
+
+int
+sourceRead(Source *s, ulong block, uchar *p, int n)
+{
+	uchar buf[VtMaxLumpSize];
+	uchar score[VtScoreSize];
+	int i, nn, np, type;
+	int elem[VtPointerDepth];
+
+	memmove(score, s->score, VtScoreSize);
+
+	np = s->psize/VtScoreSize;
+	for(i=0; i<s->depth; i++) {
+		elem[i] = block % np;
+		block /= np;
+	}
+	assert(block == 0);
+
+	for(i=s->depth-1; i>=0; i--) {
+		nn = vtRead(z, score, VtPointerType0+i, buf, s->psize);
+		if(nn < 0)
+			return -1;
+
+		if(!vtSha1Check(score, buf, nn)) {
+			vtSetError("vtSha1Check failed on root block");
+			return -1;
+		}
+
+		if((elem[i]+1)*VtScoreSize > nn)
+			return 0;
+		memmove(score, buf + elem[i]*VtScoreSize, VtScoreSize);
+	}
+
+	if(s->dir)
+		type = VtDirType;
+	else
+		type = VtDataType;
+
+	nn = vtRead(z, score, type, p, n);
+	if(nn < 0)
+		return -1;
+
+	if(!vtSha1Check(score, p, nn)) {
+		vtSetError("vtSha1Check failed on root block");
+		return -1;
+	}
+	
+	return nn;
+}
+
+void
+dumpFileContents(Source *s)
+{
+	int nb, lb, i, n;
+	uchar buf[VtMaxLumpSize];
+
+	nb = (s->size + s->dsize - 1)/s->dsize;
+	lb = s->size%s->dsize;
+	for(i=0; i<nb; i++) {
+		memset(buf, 0, s->dsize);
+		n = sourceRead(s, i, buf, s->dsize);
+		if(n < 0) {	
+			fprint(2, "could not read block: %d: %s\n", i, vtGetError());
+			continue;
+		}
+		if(i < nb-1)
+			Bwrite(bout, buf, s->dsize);
+		else
+			Bwrite(bout, buf, lb);
+	}
+}
+
+void
+dumpFile(Source *s, int indent)
+{
+	int nb, i, j, n;
+	uchar buf[VtMaxLumpSize];
+	uchar score[VtScoreSize];
+
+	nb = (s->size + s->dsize - 1)/s->dsize;
+	for(i=0; i<nb; i++) {
+		memset(buf, 0, s->dsize);
+		n = sourceRead(s, i, buf, s->dsize);
+		if(n < 0) {	
+			fprint(2, "could not read block: %d: %s\n", i, vtGetError());
+			continue;
+		}
+		for(j=0; j<indent; j++)
+			Bprint(bout, " ");
+		vtSha1(score, buf, n);		
+		Bprint(bout, "%4d: size: %ud: %V\n", i, n, score);
+	}
+}
+
+int
+dumpDir(Source *s, int indent)
+{
+	int pb, ne, nb, i, j, n, entry;
+	uchar buf[VtMaxLumpSize];
+	Source ss;
+
+	pb = s->dsize/VtEntrySize;
+	ne = pb*(s->size/s->dsize) + (s->size%s->dsize)/VtEntrySize;
+	nb = (s->size + s->dsize - 1)/s->dsize;
+	for(i=0; i<nb; i++) {
+		memset(buf, 0, s->dsize);
+		n = sourceRead(s, i, buf, s->dsize);
+		if(n < 0) {	
+			fprint(2, "could not read block: %d: %s\n", i, vtGetError());
+			continue;
+		}
+		for(j=0; j<pb; j++) {
+			entry = i*pb + j;
+			if(entry >= ne)
+				break;
+			parse(&ss, buf + j * VtEntrySize);
+
+			if(!find)
+				sourcePrint(&ss, indent, entry);
+			else if(memcmp(ss.score, fscore, VtScoreSize) == 0) {
+				dumpFileContents(&ss);
+				return 0;
+			}
+
+			if(ss.dir) {
+				if(!dumpDir(&ss, indent+1))
+					return 0;
+			} else if(all)
+				dumpFile(&ss, indent+1);
+		}
+	}
+	return 1;
+}
+
+void
+usage(void)
+{
+	fprint(2, "%s: [file]\n", argv0);
+	exits("usage");
+}
+
+int
+parseScore(uchar *score, char *buf, int n)
+{
+	int i, c;
+
+	memset(score, 0, VtScoreSize);
+
+	if(n < VtScoreSize*2)
+		return 0;
+	for(i=0; i<VtScoreSize*2; i++) {
+		if(buf[i] >= '0' && buf[i] <= '9')
+			c = buf[i] - '0';
+		else if(buf[i] >= 'a' && buf[i] <= 'f')
+			c = buf[i] - 'a' + 10;
+		else if(buf[i] >= 'A' && buf[i] <= 'F')
+			c = buf[i] - 'A' + 10;
+		else {
+			return 0;
+		}
+
+		if((i & 1) == 0)
+			c <<= 4;
+	
+		score[i>>1] |= c;
+	}
+	return 1;
+}
+
+void
+readRoot(VtRoot *root, uchar *score, char *file)
+{
+	int fd;
+	uchar buf[VtRootSize];
+	int i, n, nn;
+
+	if(file == 0)
+		fd = 0;
+	else {
+		fd = open(file, OREAD);
+		if(fd < 0)
+			sysfatal("could not open file: %s: %r\n", file);
+	}
+	n = readn(fd, buf, sizeof(buf)-1);
+	if(n < 0)
+		sysfatal("read failed: %r\n");
+	buf[n] = 0;
+	close(fd);
+
+	for(i=0; i<n; i++) {
+		if(!parseScore(score, (char*)(buf+i), n-i))
+			continue;
+		nn = vtRead(z, score, VtRootType, buf, VtRootSize);
+		if(nn >= 0) {
+			if(nn != VtRootSize)
+				sysfatal("vtRead on root too short");
+			if(!vtSha1Check(score, buf, VtRootSize))
+				sysfatal("vtSha1Check failed on root block");
+			if(!vtRootUnpack(root, buf))
+				sysfatal("could not parse root: %r");
+			return;
+		}
+	}
+
+	sysfatal("could not find root");
+}
diff --git a/src/cmd/vac/vtread.c b/src/cmd/vac/vtread.c
new file mode 100644
index 0000000..8550279
--- /dev/null
+++ b/src/cmd/vac/vtread.c
@@ -0,0 +1,126 @@
+#include "stdinc.h"
+#include <bio.h>
+
+typedef struct Source Source;
+
+struct Source
+{
+	ulong gen;
+	int psize;
+	int dsize;
+	int dir;
+	int active;
+	int depth;
+	uvlong size;
+	uchar score[VtScoreSize];
+	int reserved;
+};
+
+int bsize;
+Biobuf *bout;
+VtRootLump root;
+int ver;
+int cmp;
+int all;
+int find;
+uchar fscore[VtScoreSize];
+int dirSize;
+void (*parse)(Source*, uchar*);
+VtSession *z;
+
+int vtGetUint16(uchar *p);
+ulong vtGetUint32(uchar *p);
+uvlong vtGetUint48(uchar *p);
+void usage(void);
+int parseScore(uchar *score, char *buf, int n);
+void readRoot(VtRootLump*, uchar *score, char *file);
+void parse1(Source*, uchar*);
+void parse2(Source*, uchar*);
+int dumpDir(Source*, int indent);
+
+void
+main(int argc, char *argv[])
+{
+	char *host = nil;
+	uchar score[VtScoreSize];
+	uchar buf[VtMaxLumpSize];
+	int type;
+	int n;
+	
+	type = VtDataType;
+
+	ARGBEGIN{
+	case 't':
+		type = atoi(ARGF());
+		break;
+	}ARGEND
+
+	vtAttach();
+
+	bout = vtMemAllocZ(sizeof(Biobuf));
+	Binit(bout, 1, OWRITE);
+
+	if(argc != 1)
+		usage();
+
+	vtAttach();
+
+	fmtinstall('V', vtScoreFmt);
+	fmtinstall('R', vtErrFmt);
+
+	z = vtDial(host);
+	if(z == nil)
+		vtFatal("could not connect to server: %s", vtGetError());
+
+	if(!vtConnect(z, 0))
+		sysfatal("vtConnect: %r");
+
+	if(!parseScore(score, argv[0], strlen(argv[0])))
+		vtFatal("could not parse score: %s", vtGetError());
+
+	n = vtRead(z, score, type, buf, VtMaxLumpSize);
+	if(n < 0)
+		vtFatal("could not read block: %s", vtGetError());
+	Bwrite(bout, buf, n);
+
+	Bterm(bout);
+
+	vtClose(z);
+	vtDetach();
+	exits(0);
+}
+
+void
+usage(void)
+{
+	fprint(2, "%s: -t type score\n", argv0);
+	exits("usage");
+}
+
+int
+parseScore(uchar *score, char *buf, int n)
+{
+	int i, c;
+
+	memset(score, 0, VtScoreSize);
+
+	if(n < VtScoreSize*2)
+		return 0;
+	for(i=0; i<VtScoreSize*2; i++) {
+		if(buf[i] >= '0' && buf[i] <= '9')
+			c = buf[i] - '0';
+		else if(buf[i] >= 'a' && buf[i] <= 'f')
+			c = buf[i] - 'a' + 10;
+		else if(buf[i] >= 'A' && buf[i] <= 'F')
+			c = buf[i] - 'A' + 10;
+		else {
+			return 0;
+		}
+
+		if((i & 1) == 0)
+			c <<= 4;
+	
+		score[i>>1] |= c;
+	}
+	return 1;
+}
diff --git a/src/cmd/vac/wtest.c b/src/cmd/vac/wtest.c
new file mode 100644
index 0000000..3cc15e9
--- /dev/null
+++ b/src/cmd/vac/wtest.c
@@ -0,0 +1,47 @@
+#include "stdinc.h"
+
+enum {
+	Nblock = 10000,
+	BlockSize = 8*1024,
+};
+
+uchar data[Nblock*BlockSize];
+
+void
+main(int argc, char *argv[])
+{
+	VtSession *z;
+	int i;
+	uchar score[VtScoreSize];
+	int start;
+
+	ARGBEGIN{
+	}ARGEND
+
+	for(i=0; i<Nblock; i++) {
+		if(readn(0, data+i*BlockSize, BlockSize) < BlockSize)
+			sysfatal("read failed: %r");
+	}
+
+	vtAttach();
+
+	z = vtDial("iolaire2");
+	if(z == nil)
+		sysfatal("cound not connect to venti");
+	if(!vtConnect(z, 0))
+		vtFatal("vtConnect: %s", vtGetError());
+
+	print("starting\n");
+
+	start = times(0);
+
+	for(i=0; i<Nblock; i++) {
+		if(!vtWrite(z, score, VtDataType, data+i*BlockSize, BlockSize))
+			vtFatal("vtWrite failed: %s", vtGetError());
+	}
+
+	print("time = %f\n", (times(0) - start)*0.001);
+
+	vtClose(z);
+	vtDetach();
+}