Add cgroup v2 support while maintaining v1 compatibility

cmd/gcs/cgroup_manager_test.go

@@ -0,0 +1,122 @@
+//go:build linux
+// +build linux
+
+package main
+
+import (
+	"testing"
+
+	cgroups2stats "github.com/containerd/cgroups/v3/cgroup2/stats"
+	oci "github.com/opencontainers/runtime-spec/specs-go"
+)
+
+func TestCgroupManagerInterface_Compatibility(t *testing.T) {
+	// Test that both managers implement the CgroupManager interface.
+	// Compile-time check: these assignments will fail to compile if the types
+	// do not satisfy CgroupManager.
+	var _ CgroupManager = &V1Manager{}
+	var _ CgroupManager = &V2Manager{}
+}
+
+func TestConvertToV2Resources_Basic(t *testing.T) {
+	limit := int64(1024 * 1024 * 1024) // 1GB
+
+	ociResources := &oci.LinuxResources{
+		Memory: &oci.LinuxMemory{
+			Limit: &limit,
+		},
+	}
+
+	v2Resources := convertToV2Resources(ociResources)
+
+	if v2Resources == nil {
+		t.Fatal("v2Resources should not be nil")
+	}
+	if v2Resources.Memory == nil {
+		t.Fatal("v2Resources.Memory should not be nil")
+	}
+	if v2Resources.Memory.Max == nil || *v2Resources.Memory.Max != limit {
+		t.Errorf("Expected memory max %d, got %v", limit, v2Resources.Memory.Max)
+	}
+}
+
+func TestIsCgroupV2_Detection(t *testing.T) {
+	// Test the cgroup version detection
+	result1 := isCgroupV2()
+	result2 := isCgroupV2()
+
+	// Should be consistent
+	if result1 != result2 {
+		t.Error("isCgroupV2() should return consistent results")
+	}
+
+	t.Logf("Detected cgroup version: v%d", map[bool]int{false: 1, true: 2}[result1])
+}
+
+// Additional Error Handling and Edge Cases
+func TestCgroupManager_InvalidPath(t *testing.T) {
+	// Use a path that cannot be created due to read-only filesystem constraints
+	v2mgr := &V2Manager{path: "/proc/nonexistent/path"}
+	err := v2mgr.Create(1234)
+	if err == nil {
+		t.Error("Expected error for invalid cgroup path, got nil")
+	} else {
+		t.Logf("Expected error for invalid path: %v", err)
+	}
+}
+
+func TestCgroupManager_PermissionDenied(t *testing.T) {
+	// Test with root path that should require permissions
+	v2mgr := &V2Manager{path: "/sys/fs/cgroup/test-permission-denied"}
+	err := v2mgr.Create(1234)
+	// Error is expected, just ensure it doesn't panic
+	if err != nil {
+		t.Logf("Expected permission error: %v", err)
+	}
+}
+
+func TestConvertV2StatsToV1_InvalidInput(t *testing.T) {
+	// Test with nil input
+	result := convertV2StatsToV1Stats(nil)
+	if result == nil {
+		t.Error("convertV2StatsToV1Stats should handle nil input gracefully")
+	}
+
+	// Test with empty metrics
+	emptyMetrics := &cgroups2stats.Metrics{}
+	result = convertV2StatsToV1Stats(emptyMetrics)
+	if result == nil {
+		t.Error("convertV2StatsToV1Stats should handle empty metrics")
+	}
+}
+
+func TestConvertToV2Resources_ExtremeLimits(t *testing.T) {
+	// Test with maximum possible values
+	maxLimit := int64(^uint64(0) >> 1) // Max int64
+	ociResources := &oci.LinuxResources{
+		Memory: &oci.LinuxMemory{
+			Limit: &maxLimit,
+		},
+		Pids: &oci.LinuxPids{
+			Limit: maxLimit,
+		},
+	}
+
+	v2Resources := convertToV2Resources(ociResources)
+	if v2Resources == nil {
+		t.Fatal("v2Resources should not be nil")
+	}
+
+	// Test with zero values
+	zeroLimit := int64(0)
+	ociResourcesZero := &oci.LinuxResources{
+		Memory: &oci.LinuxMemory{
+			Limit: &zeroLimit,
+		},
+	}
+
+	v2ResourcesZero := convertToV2Resources(ociResourcesZero)
+	if v2ResourcesZero == nil || v2ResourcesZero.Memory == nil {
+		t.Error("Should handle zero limit values")
+	}
+}