Fixed FlexNBD#serve parameters, added detection of non-starting server.

tests/flexnbd.rb

@@ -16,9 +16,8 @@ class FlexNBD
     @port = port
   end
 
-  def serve(ip, port, file, *acl)
+  def serve(file, *acl)
     File.unlink(ctrl) if File.exists?(ctrl)
-    @pid = fork do
     cmd ="#{@bin} serve "\
          "--addr #{ip} "\
          "--port #{port} "\
@@ -26,9 +25,15 @@ class FlexNBD
          "--sock #{ctrl} "\
          "#{@debug} "\
          "#{acl.join(' ')}"
+    @pid = fork do
       exec(cmd)
     end
-    sleep 0.1 until File.socket?(ctrl)
+    while !File.socket?(ctrl)
+      pid, status = Process.wait2(@pid, Process::WNOHANG)
+      raise "server did not start (#{cmd})" if pid
+      sleep 0.1
+    end
+    at_exit { kill }
   end
 
   def kill

tests/nbd_scenarios

@@ -17,7 +17,6 @@ class NBDScenarios < Test::Unit::TestCase
   end
 
   def teardown
-    @nbd1.kill rescue nil
     [@filename1, @filename2].each do |f|
       File.unlink(f) if File.exists?(f)
     end
@@ -73,7 +72,7 @@ class NBDScenarios < Test::Unit::TestCase
 
   protected
   def serve1(*acl)
-    @nbd1.serve(@ip, @port1, @filename1, *acl)
+    @nbd1.serve(@filename1, *acl)
   end
 
   def writefile1(data)