hst/config: handle filesystem entry targeting root

This allows any fstype supported by hst to be directly mounted on sysroot. A special case in internal/app applies the matching entry early and excludes it from path hiding.

Closes #5.

Signed-off-by: Ophestra <cat@gensokyo.uk>

hst/hst_test.go

@@ -102,6 +102,13 @@ func TestTemplate(t *testing.T) {
 		"map_real_uid": true,
 		"device": true,
 		"filesystem": [
+			{
+				"type": "bind",
+				"dst": "/",
+				"src": "/var/lib/hakurei/base/org.debian",
+				"write": true,
+				"autoroot": true
+			},
 			{
 				"type": "ephemeral",
 				"dst": "/tmp/",
@@ -148,8 +155,6 @@ func TestTemplate(t *testing.T) {
 				"linkname": "/run/user/150"
 			}
 		],
-		"auto_root": "/var/lib/hakurei/base/org.debian",
-		"root_flags": 2,
 		"etc": "/etc/",
 		"auto_etc": true
 	}