fix: resolve resource leaks and improve namespace lifecycle management

- Fix DNS resolver leaks by creating temporary resolv.conf files within the profile's runtime directory and ensuring robust cleanup.
- Fix isolation block directory leaks by explicitly removing the block directory during namespace unpinning.
- Improve namespace lifecycle management:
    - Register processes before joining an active namespace to prevent race conditions in reference counting.
    - Update `IsLastProcess` and corresponding tests to reflect the unregister-then-check cleanup flow.
- Improve test reliability and correctness:
    - Convert `TestAppRun_ProfileDirInjection` to use separate binary execution, preventing process replacement and ensuring `t.TempDir()` cleanup.
    - Replace hardcoded test configuration paths with `t.TempDir()` in `mount_leak_test.go`.
    - Implement `SetEnvOverrides` helper for cleaner environment variable management in E2E tests.
    - Improve E2E lifecycle tests with better environment handling and output redirection.

1 files changed, 12 insertions, 7 deletions

diff --git a/tests/e2e/lifecycle_test.go b/tests/e2e/lifecycle_test.go
index 6cff0c8..ffd731f 100644
--- a/tests/e2e/lifecycle_test.go
+++ b/tests/e2e/lifecycle_test.go
@@ -1,7 +1,6 @@
 package e2e
 
 import (
-	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -48,7 +47,9 @@ func waitForLifecycle(t *testing.T, binaryPath, runtimeDir, profile string, expe
 			t.Fatalf("Timed out waiting for lifecycle state: expected active=%v", expectedActive)
 		case <-tick.C:
 			cmd := exec.Command(binaryPath, "test-lifecycle", "--profile", profile)
-			cmd.Env = append(os.Environ(), fmt.Sprintf("XDG_RUNTIME_DIR=%s", runtimeDir))
+			cmd.Env = SetEnvOverrides(map[string]string{"XDG_RUNTIME_DIR": runtimeDir})
+			cmd.Stdout = os.Stdout
+			cmd.Stderr = os.Stderr
 			err := cmd.Run()
 
 			isActive := err == nil
@@ -79,7 +80,9 @@ func TestNamespaceLifecycleAutomation(t *testing.T) {
 	t.Run("ReferenceCounting", func(t *testing.T) {
 		// Start a process that exits quickly
 		cmd1 := exec.Command(binaryPath, "--profile", "default", "--", "sleep", "1.0")
-		cmd1.Env = append(os.Environ(), fmt.Sprintf("XDG_RUNTIME_DIR=%s", tmpRuntimeDir))
+		cmd1.Env = SetEnvOverrides(map[string]string{"XDG_RUNTIME_DIR": tmpRuntimeDir})
+		cmd1.Stdout = os.Stdout
+		cmd1.Stderr = os.Stderr
 		if err := cmd1.Start(); err != nil {
 			t.Fatalf("Failed to start cmd1: %v", err)
 		}
@@ -87,9 +90,11 @@ func TestNamespaceLifecycleAutomation(t *testing.T) {
 		// Verify PID file exists using polling
 		waitForLifecycle(t, binaryPath, tmpRuntimeDir, "default", true)
 
-		// Start a second process using the same profile
-		cmd2 := exec.Command(binaryPath, "--profile", "default", "--", "sleep", "1.0")
-		cmd2.Env = append(os.Environ(), fmt.Sprintf("XDG_RUNTIME_DIR=%s", tmpRuntimeDir))
+		// Start a second process using the same profile with a longer sleep
+		cmd2 := exec.Command(binaryPath, "--profile", "default", "--", "sleep", "5.0")
+		cmd2.Env = SetEnvOverrides(map[string]string{"XDG_RUNTIME_DIR": tmpRuntimeDir})
+		cmd2.Stdout = os.Stdout
+		cmd2.Stderr = os.Stderr
 		if err := cmd2.Start(); err != nil {
 			t.Fatalf("Failed to start cmd2: %v", err)
 		}
@@ -100,7 +105,7 @@ func TestNamespaceLifecycleAutomation(t *testing.T) {
 			t.Fatalf("cmd1 failed: %v", err)
 		}
 
-		// Poll for the count to drop back to 1
+		// Poll for the count to drop back to 1 (cmd2 should still be running)
 		waitForLifecycle(t, binaryPath, tmpRuntimeDir, "default", true)
 
 		// Wait for second process to exit naturally