CR fixes

Signed-off-by: Alun Evans <[email protected]>

map.go

@@ -697,6 +697,13 @@ func ensurePerCPUSlice(sliceOrPtr any, elemLength int) (any, error) {
 			return nil, fmt.Errorf("per-cpu slice is incorrect length, expected %d, got %d",
 				possibleCPUs, sliceValue.Len())
 		}
+		if sliceOrPtrType.Elem().Kind() == reflect.Pointer {
+			for i := 0; i < sliceValue.Len(); i++ {
+				if !sliceValue.Index(i).Elem().CanAddr() {
+					return nil, fmt.Errorf("per-cpu slice elements cannot be nil")
+				}
+			}
+		}
 		return sliceValue.Interface(), nil
 	}
 
@@ -717,10 +724,8 @@ func ensurePerCPUSlice(sliceOrPtr any, elemLength int) (any, error) {
 	sliceElemType = sliceElemType.Elem()
 
 	for i := 0; i < possibleCPUs; i++ {
-		if sliceElemIsPointer {
-			newElem := reflect.New(sliceElemType)
-			slice.Index(i).Set(newElem)
-		}
+		newElem := reflect.New(sliceElemType)
+		slice.Index(i).Set(newElem)
 	}
 
 	return slice.Interface(), nil

map_test.go

@@ -1350,6 +1350,9 @@ func TestPerCPUMarshaling(t *testing.T) {
 
 			// Make sure unmarshaling works on slices containing pointers
 			retrievedVal := make([]*customEncoding, numCPU)
+			if err := arr.Lookup(uint32(0), retrievedVal); err == nil {
+				t.Fatal("Slices with nil values should generate error")
+			}
 			for i := range retrievedVal {
 				retrievedVal[i] = &customEncoding{}
 			}

marshalers.go

@@ -84,7 +84,7 @@ func marshalPerCPUValue(slice any, elemLength int) (sys.Pointer, error) {
 // unmarshalPerCPUValue decodes a buffer into a slice containing one value per
 // possible CPU.
 //
-// slicePtr must be a pointer to a slice.
+// slice must be a literal slice and not a pointer.
 func unmarshalPerCPUValue(slice any, elemLength int, buf []byte) error {
 	sliceType := reflect.TypeOf(slice)
 	if sliceType.Kind() != reflect.Slice {
@@ -97,7 +97,12 @@ func unmarshalPerCPUValue(slice any, elemLength int, buf []byte) error {
 	}
 
 	sliceValue := reflect.ValueOf(slice)
-
+	if sliceValue.Len() < possibleCPUs {
+		// Should be impossible here from ensurePerCPUSlice(),
+		// but avoid a panic in the loop.
+		return fmt.Errorf("per-cpu value slice len %q is less than possibleCPU %q",
+			sliceValue.Len(), possibleCPUs)
+	}
 	sliceElemType := sliceType.Elem()
 	sliceElemIsPointer := sliceElemType.Kind() == reflect.Ptr
 	stride := internal.Align(elemLength, 8)