libpod: don't warn about cgroupsv1 on FreeBSD

This factors out the check for cgroupsv2 unified mode into a
platform-specific file and stops podman from generating a (harmless)
warning every time it is run on FreeBSD.

[NO NEW TESTS NEEDED]

Signed-off-by: Doug Rabson <dfr@rabson.org>

libpod/runtime_linux.go

@@ -0,0 +1,45 @@
+//go:build !remote
+
+package libpod
+
+import (
+	"errors"
+	"fmt"
+	"os"
+
+	"golang.org/x/sys/unix"
+
+	"github.com/containers/common/pkg/cgroups"
+	"github.com/containers/podman/v5/pkg/rootless"
+	"github.com/containers/podman/v5/pkg/systemd"
+	"github.com/sirupsen/logrus"
+)
+
+func checkCgroups2UnifiedMode(runtime *Runtime) {
+	unified, _ := cgroups.IsCgroup2UnifiedMode()
+	// DELETE ON RHEL9
+	if !unified {
+		_, ok := os.LookupEnv("PODMAN_IGNORE_CGROUPSV1_WARNING")
+		if !ok {
+			logrus.Warn("Using cgroups-v1 which is deprecated in favor of cgroups-v2 with Podman v5 and will be removed in a future version. Set environment variable `PODMAN_IGNORE_CGROUPSV1_WARNING` to hide this warning.")
+		}
+	}
+	// DELETE ON RHEL9
+
+	if unified && rootless.IsRootless() && !systemd.IsSystemdSessionValid(rootless.GetRootlessUID()) {
+		// If user is rootless and XDG_RUNTIME_DIR is found, podman will not proceed with /tmp directory
+		// it will try to use existing XDG_RUNTIME_DIR
+		// if current user has no write access to XDG_RUNTIME_DIR we will fail later
+		if err := unix.Access(runtime.storageConfig.RunRoot, unix.W_OK); err != nil {
+			msg := fmt.Sprintf("RunRoot is pointing to a path (%s) which is not writable. Most likely podman will fail.", runtime.storageConfig.RunRoot)
+			if errors.Is(err, os.ErrNotExist) {
+				// if dir does not exist, try to create it
+				if err := os.MkdirAll(runtime.storageConfig.RunRoot, 0700); err != nil {
+					logrus.Warn(msg)
+				}
+			} else {
+				logrus.Warnf("%s: %v", msg, err)
+			}
+		}
+	}
+}