Allow users to add host user accounts to /etc/passwd

Some containers require certain user account(s) to exist within the
container when they are run. This option will allow callers to add a
bunch of passwd entries from the host to the container even if the
entries are not in the local /etc/passwd file on the host.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1935831

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

pkg/util/utils.go

@@ -723,3 +723,11 @@ func SocketPath() (string, error) {
 	// Glue the socket path together
 	return filepath.Join(xdg, "podman", "podman.sock"), nil
 }
+
+func LookupUser(name string) (*user.User, error) {
+	// Assume UID look up first, if it fails lookup by username
+	if u, err := user.LookupId(name); err == nil {
+		return u, err
+	}
+	return user.Lookup(name)
+}