Refactor bridge files into templates

This allows better extensibility, as well as provides more uniform way
of config file generation.

gen_machines.py

@@ -51,11 +51,20 @@ bridges = {}
 for i, n in [(x, 'net_'+str(x)) for x in range(1, 8)]:
 	bridges[i] = Bridge(n, i)
 
-def dump_bridges(fn):
-	with open(fn, 'w+') as f:
-		for br in bridges:
-			# Generate bridge.conf for the host
-			f.write('allow ' + bridges[br].name + '\n')
+def gen_bridge_files():
+	files = [
+		'bridge.conf',
+		'gen_bridges.sh',
+		]
+		context = {'bridges': bridges}
+	
+		loader = jinja2.FileSystemLoader('templates/')
+		environment = jinja2.Environment(loader=loader, trim_blocks=True, keep_trailing_newline=True)
+		for f in files:
+			template = environment.get_template(f)
+			template.stream(context).dump('output/' + f)
+		mode = os.stat('output/gen_bridges.sh').st_mode
+		os.chmod('output/gen_bridges.sh', mode | 0o0100)
 
 # Connections
 # dict[ net_num -> [comp_names]
@@ -78,7 +87,7 @@ for net, cs in conns.items():
 		comps[c].add_to_bridge(bridges[net])
 
 os.mkdir('output')
-dump_bridges('output/bridge.conf')
+gen_bridge_files()
 
 for c in comps.values():
 	c.gen_files()

templates/bridge.conf

@@ -0,0 +1,3 @@
+{% for b in bridges %}
+allow {{ b.name }}
+{% endfor %}

templates/gen_bridges.sh

@@ -0,0 +1,8 @@
+#!/bin/sh
+
+# Run as root.
+
+{% for b in bridges %}
+ip link add name {{ b.name }} type bridge
+ip link set {{ b.name }} up
+{% endfor %}