System tests: add podman system check tests

Testing `podman system check` requires that we have a way to
intentionally introduce storage corruptions.  Add a hidden `podman
testing` command that provides the necessary internal logic in
subcommands.  Stub out the tunnel implementation for now.

Signed-off-by: Nalin Dahyabhai <nalin@redhat.com>

cmd/podman-testing/main.go

@@ -0,0 +1,128 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+	"syscall"
+
+	"github.com/containers/common/pkg/config"
+	_ "github.com/containers/podman/v5/cmd/podman/completion"
+	ientities "github.com/containers/podman/v5/internal/domain/entities"
+	"github.com/containers/podman/v5/internal/domain/infra"
+	"github.com/containers/podman/v5/pkg/domain/entities"
+	"github.com/containers/storage"
+	"github.com/containers/storage/pkg/reexec"
+	"github.com/containers/storage/pkg/unshare"
+	"github.com/sirupsen/logrus"
+	"github.com/spf13/cobra"
+)
+
+var (
+	mainCmd = &cobra.Command{
+		Use:  "podman-testing",
+		Long: "Assorted tools for use in testing podman",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return cmd.Help()
+		},
+		PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
+			return before()
+		},
+		PersistentPostRunE: func(cmd *cobra.Command, args []string) error {
+			return after()
+		},
+		SilenceUsage:  true,
+		SilenceErrors: true,
+	}
+	mainContext          = context.Background()
+	podmanConfig         entities.PodmanConfig
+	globalStorageOptions storage.StoreOptions
+	globalLogLevel       string
+	testingEngine        ientities.TestingEngine
+)
+
+func init() {
+	podmanConfig.FlagSet = mainCmd.PersistentFlags()
+	fl := mainCmd.PersistentFlags()
+	fl.StringVar(&podmanConfig.DockerConfig, "docker-config", os.Getenv("DOCKER_CONFIG"), "path to .docker/config")
+	fl.StringVar(&globalLogLevel, "log-level", "warn", "logging level")
+	fl.StringVar(&podmanConfig.URI, "url", "", "URL to access Podman service")
+	fl.StringVar(&podmanConfig.RegistriesConf, "registries-conf", os.Getenv("REGISTRIES_CONF"), "path to registries.conf (REGISTRIES_CONF)")
+}
+
+func before() error {
+	if globalLogLevel != "" {
+		parsedLogLevel, err := logrus.ParseLevel(globalLogLevel)
+		if err != nil {
+			return fmt.Errorf("parsing log level %q: %w", globalLogLevel, err)
+		}
+		logrus.SetLevel(parsedLogLevel)
+	}
+	if err := storeBefore(); err != nil {
+		return fmt.Errorf("setting up storage: %w", err)
+	}
+
+	podmanConfig.EngineMode = engineMode
+	podmanConfig.Remote = podmanConfig.URI != ""
+
+	containersConf, err := config.Default()
+	if err != nil {
+		return fmt.Errorf("loading default configuration (may reference $CONTAINERS_CONF): %w", err)
+	}
+	podmanConfig.ContainersConfDefaultsRO = containersConf
+	containersConf, err = config.New(nil)
+	if err != nil {
+		return fmt.Errorf("loading default configuration (may reference $CONTAINERS_CONF): %w", err)
+	}
+	podmanConfig.ContainersConf = containersConf
+
+	podmanConfig.StorageDriver = globalStorageOptions.GraphDriverName
+	podmanConfig.GraphRoot = globalStorageOptions.GraphRoot
+	podmanConfig.Runroot = globalStorageOptions.RunRoot
+	podmanConfig.ImageStore = globalStorageOptions.ImageStore
+	podmanConfig.StorageOpts = globalStorageOptions.GraphDriverOptions
+	podmanConfig.TransientStore = globalStorageOptions.TransientStore
+
+	te, err := infra.NewTestingEngine(&podmanConfig)
+	if err != nil {
+		return fmt.Errorf("initializing libpod: %w", err)
+	}
+	testingEngine = te
+	return nil
+}
+
+func after() error {
+	if err := storeAfter(); err != nil {
+		return fmt.Errorf("shutting down storage: %w", err)
+	}
+	return nil
+}
+
+func main() {
+	if reexec.Init() {
+		// We were invoked with a different argv[0] indicating that we
+		// had a specific job to do as a subprocess, and it's done.
+		return
+	}
+	unshare.MaybeReexecUsingUserNamespace(false)
+
+	exitCode := 1
+	if err := mainCmd.Execute(); err != nil {
+		if logrus.IsLevelEnabled(logrus.TraceLevel) {
+			fmt.Fprintf(os.Stderr, "Error: %+v\n", err)
+		} else {
+			fmt.Fprintf(os.Stderr, "Error: %v\n", err)
+		}
+		var ee *exec.ExitError
+		if errors.As(err, &ee) {
+			if w, ok := ee.Sys().(syscall.WaitStatus); ok {
+				exitCode = w.ExitStatus()
+			}
+		}
+	} else {
+		exitCode = 0
+	}
+	os.Exit(exitCode)
+}