fix hamt delete issue

License: MIT
Signed-off-by: Jeromy <jeromyj@gmail.com>

unixfs/hamt/hamt.go

@@ -492,16 +492,21 @@ func (ds *HamtShard) modifyValue(ctx context.Context, hv *hashBits, key string,
 
 		return nil
 	case *shardValue:
-		switch {
-		case val == nil: // passing a nil value signifies a 'delete'
+		if child.key == key {
+			// value modification
+			if val == nil {
 				ds.bitfield.SetBit(ds.bitfield, idx, 0)
 				return ds.rmChild(cindex)
+			}
 
-		case child.key == key: // value modification
 			child.val = val
 			return nil
+		} else {
+			if val == nil {
+				return os.ErrNotExist
+			}
 
-		default: // replace value with another shard, one level deeper
+			// replace value with another shard, one level deeper
 			ns, err := NewHamtShard(ds.dserv, ds.tableSize)
 			if err != nil {
 				return err

unixfs/hamt/hamt_test.go

@@ -222,6 +222,20 @@ func TestRemoveElems(t *testing.T) {
 	}
 	ctx := context.Background()
 
+	for i := 0; i < 100; i++ {
+		err := s.Remove(ctx, fmt.Sprintf("NOTEXIST%d", rand.Int()))
+		if err != os.ErrNotExist {
+			t.Fatal("shouldnt be able to remove things that don't exist")
+		}
+	}
+
+	for _, d := range dirs {
+		_, err := s.Find(ctx, d)
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+
 	shuffle(time.Now().UnixNano(), dirs)
 
 	for _, d := range dirs {

unixfs/hamt/util.go

@@ -2,6 +2,7 @@ package hamt
 
 import (
 	"math/big"
+	"math/bits"
 )
 
 // hashBits is a helper that allows the reading of the 'next n bits' as an integer.
@@ -39,25 +40,10 @@ func (hb *hashBits) Next(i int) int {
 	}
 }
 
-const (
-	m1  = 0x5555555555555555 //binary: 0101...
-	m2  = 0x3333333333333333 //binary: 00110011..
-	m4  = 0x0f0f0f0f0f0f0f0f //binary:  4 zeros,  4 ones ...
-	h01 = 0x0101010101010101 //the sum of 256 to the power of 0,1,2,3...
-)
-
-// from https://en.wikipedia.org/wiki/Hamming_weight
-func popCountUint64(x uint64) int {
-	x -= (x >> 1) & m1             //put count of each 2 bits into those 2 bits
-	x = (x & m2) + ((x >> 2) & m2) //put count of each 4 bits into those 4 bits
-	x = (x + (x >> 4)) & m4        //put count of each 8 bits into those 8 bits
-	return int((x * h01) >> 56)
-}
-
 func popCount(i *big.Int) int {
 	var n int
 	for _, v := range i.Bits() {
-		n += popCountUint64(uint64(v))
+		n += bits.OnesCount64(uint64(v))
 	}
 	return n
 }