rootless: support `podman network create` (CNI-in-slirp4netns)

Usage:
```
$ podman network create foo
$ podman run -d --name web --hostname web --network foo nginx:alpine
$ podman run --rm --network foo alpine wget -O - http://web.dns.podman
Connecting to web.dns.podman (10.88.4.6:80)
...
<h1>Welcome to nginx!</h1>
...
```

See contrib/rootless-cni-infra for the design.

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

1 files changed, 4 insertions, 0 deletions

diff --git a/libpod/runtime_ctr.go b/libpod/runtime_ctr.go
index fa91fe002..6c29e0577 100644
--- a/libpod/runtime_ctr.go
+++ b/libpod/runtime_ctr.go
@@ -770,7 +770,11 @@ func (r *Runtime) LookupContainer(idOrName string) (*Container, error) {
 func (r *Runtime) GetContainers(filters ...ContainerFilter) ([]*Container, error) {
 	r.lock.RLock()
 	defer r.lock.RUnlock()
+	return r.GetContainersWithoutLock(filters...)
+}
 
+// GetContainersWithoutLock is same as GetContainers but without lock
+func (r *Runtime) GetContainersWithoutLock(filters ...ContainerFilter) ([]*Container, error) {
 	if !r.valid {
 		return nil, define.ErrRuntimeStopped
 	}