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util/deephash: fix map hashing when key & element have the same type
Regression from09afb8e35b
, in which the same reflect.Value scratch value was being used as the map iterator copy destination. Also: make nil and empty maps hash differently, add test. Fixes #4871 Co-authored-by: Josh Bleecher Snyder <josharian@gmail.com> Change-Id: I67f42524bc81f694c1b7259d6682200125ea4a66 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com> (cherry picked from commit757ecf7e80
)
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@ -98,10 +98,14 @@ func (s Sum) String() string {
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}
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}
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var (
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var (
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once sync.Once
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seedOnce sync.Once
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seed uint64
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seed uint64
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)
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)
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func initSeed() {
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seed = uint64(time.Now().UnixNano())
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}
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func (h *hasher) sum() (s Sum) {
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func (h *hasher) sum() (s Sum) {
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h.bw.Flush()
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h.bw.Flush()
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// Sum into scratch & copy out, as hash.Hash is an interface
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// Sum into scratch & copy out, as hash.Hash is an interface
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@ -121,9 +125,7 @@ func Hash(v any) (s Sum) {
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h := hasherPool.Get().(*hasher)
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h := hasherPool.Get().(*hasher)
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defer hasherPool.Put(h)
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defer hasherPool.Put(h)
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h.reset()
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h.reset()
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once.Do(func() {
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seedOnce.Do(initSeed)
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seed = uint64(time.Now().UnixNano())
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})
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h.hashUint64(seed)
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h.hashUint64(seed)
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h.hashValue(reflect.ValueOf(v))
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h.hashValue(reflect.ValueOf(v))
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return h.sum()
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return h.sum()
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@ -298,9 +300,9 @@ func (h *hasher) hashValue(v reflect.Value) {
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}
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}
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type mapHasher struct {
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type mapHasher struct {
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h hasher
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h hasher
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val valueCache // re-usable values for map iteration
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valKey, valElem valueCache // re-usable values for map iteration
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iter reflect.MapIter // re-usable map iterator
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iter reflect.MapIter // re-usable map iterator
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}
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}
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var mapHasherPool = &sync.Pool{
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var mapHasherPool = &sync.Pool{
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@ -334,8 +336,12 @@ func (h *hasher) hashMap(v reflect.Value) {
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defer iter.Reset(reflect.Value{}) // avoid pinning v from mh.iter when we return
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defer iter.Reset(reflect.Value{}) // avoid pinning v from mh.iter when we return
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var sum Sum
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var sum Sum
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k := mh.val.get(v.Type().Key())
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if v.IsNil() {
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e := mh.val.get(v.Type().Elem())
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sum.sum[0] = 1 // something non-zero
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}
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k := mh.valKey.get(v.Type().Key())
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e := mh.valElem.get(v.Type().Elem())
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mh.h.visitStack = h.visitStack // always use the parent's visit stack to avoid cycles
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mh.h.visitStack = h.visitStack // always use the parent's visit stack to avoid cycles
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for iter.Next() {
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for iter.Next() {
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k.SetIterKey(iter)
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k.SetIterKey(iter)
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@ -11,9 +11,11 @@
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"crypto/sha256"
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"crypto/sha256"
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"fmt"
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"fmt"
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"math"
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"math"
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"math/rand"
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"reflect"
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"reflect"
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"runtime"
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"runtime"
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"testing"
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"testing"
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"testing/quick"
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"go4.org/mem"
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"go4.org/mem"
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"inet.af/netaddr"
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"inet.af/netaddr"
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@ -141,6 +143,40 @@ func TestIssue4868(t *testing.T) {
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}
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}
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}
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}
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func TestIssue4871(t *testing.T) {
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m1 := map[string]string{"": "", "x": "foo"}
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m2 := map[string]string{}
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if h1, h2 := Hash(m1), Hash(m2); h1 == h2 {
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t.Errorf("bogus: h1=%x, h2=%x", h1, h2)
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}
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}
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func TestNilVsEmptymap(t *testing.T) {
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m1 := map[string]string(nil)
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m2 := map[string]string{}
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if h1, h2 := Hash(m1), Hash(m2); h1 == h2 {
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t.Errorf("bogus: h1=%x, h2=%x", h1, h2)
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}
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}
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func TestMapFraming(t *testing.T) {
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m1 := map[string]string{"foo": "", "fo": "o"}
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m2 := map[string]string{}
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if h1, h2 := Hash(m1), Hash(m2); h1 == h2 {
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t.Errorf("bogus: h1=%x, h2=%x", h1, h2)
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}
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}
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func TestQuick(t *testing.T) {
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initSeed()
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err := quick.Check(func(v, w map[string]string) bool {
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return (Hash(v) == Hash(w)) == reflect.DeepEqual(v, w)
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}, &quick.Config{MaxCount: 1000, Rand: rand.New(rand.NewSource(int64(seed)))})
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if err != nil {
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t.Fatalf("seed=%v, err=%v", seed, err)
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}
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}
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func getVal() []any {
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func getVal() []any {
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return []any{
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return []any{
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&wgcfg.Config{
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&wgcfg.Config{
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