Add utility function to convert uint64 to uint32 securely

Author: epapbak

types/conversion.go

@@ -0,0 +1,29 @@
+// Copyright 2024 Red Hat, Inc
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package types
+
+import (
+	"errors"
+)
+
+// Uint64ToUint32 safely converts a uint64 into a uint32 without overflow
+func Uint64ToUint32(v uint64) (uint32, error) {
+	// Check for overflow without casting
+	if v > uint64(^uint32(0)) { // ^uint32(0) is the maximum uint32 value (4,294,967,295)
+		return 0, errors.New("value exceeds uint32 range")
+	}
+
+	return uint32(v), nil // #nosec G103: safe after bounds check
+}

types/conversion_test.go

@@ -0,0 +1,33 @@
+package types
+
+import (
+	"testing"
+)
+
+func TestUint64ToUint32(t *testing.T) {
+	tests := []struct {
+		name    string
+		input   uint64
+		want    uint32
+		wantErr bool
+	}{
+		{"Zero", 0, 0, false},
+		{"Max uint32", 4294967295, 4294967295, false},
+		{"Overflow", 4294967296, 0, true},
+		{"Large overflow", 18446744073709551615, 0, true},
+		{"Mid-range value", 2147483648, 2147483648, false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := Uint64ToUint32(tt.input)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("Uint64ToUint32() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if got != tt.want {
+				t.Errorf("Uint64ToUint32() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}