AES-XTS VFS (#171)

Co-authored-by: Ben Krieger <ben.krieger@intel.com>

internal/util/math.go

@@ -0,0 +1,22 @@
+package util
+
+func abs(n int) int {
+	if n < 0 {
+		return -n
+	}
+	return n
+}
+
+func GCD(m, n int) int {
+	for n != 0 {
+		m, n = n, m%n
+	}
+	return abs(m)
+}
+
+func LCM(m, n int) int {
+	if n == 0 {
+		return 0
+	}
+	return abs(n) * (abs(m) / GCD(m, n))
+}

internal/util/math_test.go

@@ -0,0 +1,82 @@
+package util
+
+import (
+	"math"
+	"testing"
+)
+
+func Test_abs(t *testing.T) {
+	tests := []struct {
+		arg  int
+		want int
+	}{
+		{0, 0},
+		{1, 1},
+		{-1, 1},
+		{math.MaxInt, math.MaxInt},
+		{math.MinInt, math.MinInt},
+	}
+	for _, tt := range tests {
+		t.Run("", func(t *testing.T) {
+			if got := abs(tt.arg); got != tt.want {
+				t.Errorf("abs(%d) = %d, want %d", tt.arg, got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_GCD(t *testing.T) {
+	tests := []struct {
+		arg1 int
+		arg2 int
+		want int
+	}{
+		{0, 0, 0},
+		{0, 1, 1},
+		{1, 0, 1},
+		{1, 1, 1},
+		{2, 3, 1},
+		{42, 56, 14},
+		{48, -18, 6},
+		{1e9, 1e9, 1e9},
+		{1e9, -1e9, 1e9},
+		{-1e9, -1e9, 1e9},
+		{math.MaxInt, math.MaxInt, math.MaxInt},
+		{math.MinInt, math.MinInt, math.MinInt},
+	}
+	for _, tt := range tests {
+		t.Run("", func(t *testing.T) {
+			if got := GCD(tt.arg1, tt.arg2); got != tt.want {
+				t.Errorf("gcd(%d, %d) = %d, want %d", tt.arg1, tt.arg2, got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_LCM(t *testing.T) {
+	tests := []struct {
+		arg1 int
+		arg2 int
+		want int
+	}{
+		{0, 0, 0},
+		{0, 1, 0},
+		{1, 0, 0},
+		{1, 1, 1},
+		{2, 3, 6},
+		{42, 56, 168},
+		{48, -18, 144},
+		{1e9, 1e9, 1e9},
+		{1e9, -1e9, 1e9},
+		{-1e9, -1e9, 1e9},
+		{math.MaxInt, math.MaxInt, math.MaxInt},
+		{math.MinInt, math.MinInt, math.MinInt},
+	}
+	for _, tt := range tests {
+		t.Run("", func(t *testing.T) {
+			if got := LCM(tt.arg1, tt.arg2); got != tt.want {
+				t.Errorf("lcm(%d, %d) = %d, want %d", tt.arg1, tt.arg2, got, tt.want)
+			}
+		})
+	}
+}