dev_container: Improve support for podman

Commit 95b80d1 made the dev container persistent between invocations,
but hard-coded `docker` again. This change fixes that and also adds
further improvements:
- Do not use `--privileged` with podman. If the rootless user has
  permissions to access `/dev/kvm`, so will the container.
- Map `/dev/vhost-net` and `/dev/vhost-vsock` as well.
- Use `BASH_SOURCE` to find this script's directory. As we're using Bash
  to start with, this is more robust than using plain `$0`.

BUG=None
TEST=Run `./tools/dev_container cargo build` with Podman and Docker

Change-Id: I05c699f327c8e1c4f3c4df9679ee92bf7e609e2e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3295372
Reviewed-by: Dennis Kempin <denniskempin@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Commit-Queue: Christian Blichmann <cblichmann@google.com>

tools/dev_container

@@ -21,7 +21,7 @@
 #   ./tools/dev_container --hermetic CMD
 
 set -e
-cd "$(dirname "$0")/.."
+cd "$(dirname "${BASH_SOURCE[0]}")/.."
 
 # Allow to override the container CLI tool, similar to the Makefile. Try
 # "docker" first and fall back to "podman".
@@ -41,13 +41,23 @@ if [ -t 1 ]; then
     )
 fi
 
+# Podman will not share devices when `--privileged` is specified
+PRIV_ARGS=()
+if [ "${DOCKER}" != "${podman}" ]; then
+    PRIV_ARGS+=(
+        --privileged
+    )
+fi
+
 DOCKER_ARGS=(
     "${TTY_ARGS[@]}"
     --volume "$(pwd):/workspace:rw"
-    --device "/dev/net/tun"
     --device "/dev/kvm"
     --volume "/dev/log:/dev/log"
-    --privileged
+    --device "/dev/net/tun"
+    --device "/dev/vhost-net"
+    --device "/dev/vhost-vsock"
+    "${PRIV_ARGS[@]}"
     "gcr.io/crosvm-packages/crosvm_dev:$IMAGE_VERSION"
 )
 
@@ -62,7 +72,7 @@ docker_run() {
 }
 
 get_container_id() {
-    docker ps -q -f name="${CONTAINER_NAME}"
+    "${DOCKER}" ps -q -f name="${CONTAINER_NAME}"
 }
 
 docker_exec() {
@@ -77,7 +87,7 @@ docker_exec() {
 main() {
     if [[ "$1" == "--stop" ]]; then
         if [ -n "$(get_container_id)" ]; then
-            docker rm -f "$(get_container_id)" >/dev/null
+            "${DOCKER}" rm -f "$(get_container_id)" >/dev/null
         fi
         exit
     fi