more functional general tester; better signal handling and details in xv6 tester

tester/run-xv6-command.sh

@@ -1,29 +1,38 @@
 #! /usr/bin/env expect
 
+proc shutdown {} {
+    # send command to halt qemu (ctrl-a x)
+    # https://stackoverflow.com/questions/27050473/how-to-send-ctrl-a-then-d-in-expect
+    send "\x01"; send "x"
+    # make sure to wait for it all to stop
+    # (without this, script was terminating before qemu quit -> bad)
+    expect eof
+}
+
 # turn off timeout (perhaps make this flexible later)
 set timeout -1
 
 # build and launch xv6 on qemu
-spawn make qemu-nox
+spawn make [lindex $argv 0] -f [lindex $argv 1] qemu-nox
+
+trap {
+    shutdown
+    exit 0
+} SIGINT
 
 # wait for initial prompt
 expect "init: starting sh\r"
 expect "$ "
 
 # send command as per command line
-send "$argv\r"
+send "[lindex $argv 2]\r"
 
 # wait for it to be done
 expect "$ "
 
-# send command to halt qemu (ctrl-a x)
-# how to do so found here:
-# https://stackoverflow.com/questions/27050473/how-to-send-ctrl-a-then-d-in-expect
-send "\x01"; send "x"
-
-# make sure to wait for it all to stop
-# (without this, script was terminating before qemu quit -> bad)
-interact
+# shutdown qemu properly (avoid runaways)
+shutdown
+