Support readonly rootfs contains colon

Fix: https://github.com/containers/podman/issues/11913

Signed-off-by: chenkang <kongchen28@gmail.com>

pkg/specgen/specgen.go

@@ -552,10 +552,10 @@ func NewSpecGenerator(arg string, rootfs bool) *SpecGenerator {
 	if rootfs {
 		csc.Rootfs = arg
 		// check if rootfs is actually overlayed
-		parts := strings.SplitN(csc.Rootfs, ":", 2)
+		lastColonIndex := strings.LastIndex(csc.Rootfs, ":")
-		if len(parts) > 1 && parts[1] == "O" {
+		if lastColonIndex != -1 && lastColonIndex+1 < len(csc.Rootfs) && csc.Rootfs[lastColonIndex+1:] == "O" {
 			csc.RootfsOverlay = true
-			csc.Rootfs = parts[0]
+			csc.Rootfs = csc.Rootfs[:lastColonIndex]
 		}
 	} else {
 		csc.Image = arg

pkg/specgen/specgen_test.go

@@ -0,0 +1,25 @@
+package specgen
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNewSpecGeneratorWithRootfs(t *testing.T) {
+	tests := []struct {
+		rootfs                string
+		expectedRootfsOverlay bool
+		expectedRootfs        string
+	}{
+		{"/root/a:b:O", true, "/root/a:b"},
+		{"/root/a:b/c:O", true, "/root/a:b/c"},
+		{"/root/a:b/c:", false, "/root/a:b/c:"},
+		{"/root/a/b", false, "/root/a/b"},
+	}
+	for _, args := range tests {
+		val := NewSpecGenerator(args.rootfs, true)
+		assert.Equal(t, val.RootfsOverlay, args.rootfs)
+		assert.Equal(t, val.Rootfs, args.rootfs)
+	}
+}