lvc: reinstate VMcommand's ability to run commands and get results

This modifies the inittab to run a very simple loop on d-i's ttyS0
that reads commands from stdin, runs them and tops and tails the
output with various control characters to make it easier to see
when we have a result.

It outputs a BEL (Ctrl-G, \a, \007) at the start, then an STX (\002)
before running the command, and an ETX (\003) afterwards, to bracket
STDOUT.  After the ETX comes the command's return code, in decimal,
then a US (\037), then comes the STDERR, and finally a NUL (\000)

That lets us send an 'exit' and look for a BEL then issue
a command and find the values required to populate the @returncode,
@stdout and @stderr values.

2 files changed, 41 insertions, 18 deletions

diff --git a/cucumber/features/step_definitions/common_steps.rb b/cucumber/features/step_definitions/common_steps.rb
index 328c5661..6f47bb93 100644
--- a/cucumber/features/step_definitions/common_steps.rb
+++ b/cucumber/features/step_definitions/common_steps.rb
@@ -208,6 +208,11 @@ When /^I start the computer$/ do
   post_vm_start_hook
 end
 
+When /^I execute "([^"]*)"$/ do |cmd|
+  info_log($vm.execute(cmd))
+end
+
+
 Given /^I start Tails( from DVD)?( with network unplugged)?( and I login)?$/ do |dvd_boot, network_unplugged, do_login|
   step "the computer is set to boot from the Tails DVD" if dvd_boot
   if network_unplugged.nil?
@@ -289,7 +294,14 @@ Given /^I select the install mode$/ do
 
   @screen.type(Sikuli::Key.TAB)
   @boot_options = "" if @boot_options.nil?
-  @screen.type(' preseed/early_command="echo DPMS=-s\\\\ 0 > /lib/debian-installer.d/S61Xnoblank ; sed -i /XF86_Switch_VT_/s/F/XF86_Switch_VT_/ /usr/share/X11/xkb/symbols/srvr_ctrl ; echo ttyS0::askfirst:-/bin/sh>>/etc/inittab;kill -HUP 1" blacklist=psmouse ' + @boot_options +
+  initcmd = 'printf \\\\\\\\07; while read x; do printf \\\\\\\\02; eval $x 2>/tmp/.remcmd_stderr; printf \\\\\\\\03%%s\\\\\\\\037 $?; cat /tmp/.remcmd_stderr; printf \\\\\\\\00; done'.gsub(/([$\\;>])/, '\\\\\0')
+  inittab_line = ('ttyS0::respawn:-/bin/sh -c \\\\047' + initcmd + '\\\\047').gsub(/ /, '\\ ')
+  @screen.type( ' preseed/early_command="echo DPMS=-s\\\\ 0 > /lib/debian-installer.d/S61Xnoblank;' +
+		' sed -i /XF86_Switch_VT_/s/F/XF86_Switch_VT_/ /usr/share/X11/xkb/symbols/srvr_ctrl;' +
+		' set -x;' +
+		' { printf ' + inittab_line + ';echo;}>>/etc/inittab;' +
+		' kill -HUP 1" blacklist=psmouse ' +
+		@boot_options +
                Sikuli::Key.ENTER)
   debug_log("debug: wait for the remote shell to respond...", :color => :blue)
   $vm.wait_until_remote_shell_is_up
diff --git a/cucumber/features/support/helpers/exec_helper.rb b/cucumber/features/support/helpers/exec_helper.rb
index 8be1e5c4..70d22d37 100644
--- a/cucumber/features/support/helpers/exec_helper.rb
+++ b/cucumber/features/support/helpers/exec_helper.rb
@@ -13,9 +13,8 @@ class VMCommand
 
   def VMCommand.wait_until_remote_shell_is_up(vm, timeout = 180)
     try_for(timeout, :msg => "Remote shell seems to be down") do
-    sleep(20)
-      Timeout::timeout(10) do
-        VMCommand.execute(vm, "echo 'true'")
+      Timeout::timeout(20) do
+        VMCommand.execute(vm, "echo 'hello?'")
       end
     end
   end
@@ -36,26 +35,38 @@ class VMCommand
     socket = TCPSocket.new("127.0.0.1", vm.get_remote_shell_port)
     debug_log("#{type}ing as #{options[:user]}: #{cmd}")
     begin
-      #socket.puts(JSON.dump([type, options[:user], cmd]))
-      socket.puts( "\n")
-      sleep(1)
-      socket.puts( "\003")
-      sleep(1)
-      socket.puts( cmd + "\n")
-      sleep(1)
+      sleep 0.5
+      while socket.ready?
+        s = socket.recv(1024)
+        debug_log("#{type} pre-exit-debris: #{s}") if not(options[:spawn])
+      end
+      socket.puts( "\nexit\n")
+      sleep 1
+      s = socket.readline(sep = "\007")
+      debug_log("#{type} post-exit-read: #{s}") if not(options[:spawn])
       while socket.ready?
-        s = socket.readline(sep = "\n").chomp("\n")
-        debug_log("#{type} read: #{s}") if not(options[:spawn])
-        if ('true' == s) then
-          break
-        end
+        s = socket.recv(1024)
+        debug_log("#{type} post-exit-debris: #{s}") if not(options[:spawn])
       end
+      socket.puts( cmd + "\n")
+      s = socket.readline(sep = "\000")
+      debug_log("#{type} post-cmd-read: #{s}") if not(options[:spawn])
+      s.chomp!("\000")
     ensure
+      debug_log("closing the remote-command socket") if not(options[:spawn])
       socket.close
     end
-    if ('true' == s)
-      return true
+    (s, s_err, x) = s.split("\037")
+    s_err = "" if s_err.nil?
+    (s, s_retcode, y) = s.split("\003")
+    (s, s_out, z) = s.split("\002")
+    s_out = "" if s_out.nil?
+
+    if (s_retcode.to_i.to_s == s_retcode.to_s && x.nil? && y.nil? && z.nil?) then
+      debug_log("returning [returncode=`#{s_retcode.to_i}`,\n\toutput=`#{s_out}`,\n\tstderr=`#{s_err}`]\nwhile discarding `#{s}`.") if not(options[:spawn])
+      return [s_retcode.to_i, s_out, s_err]
     else
+      debug_log("failed to parse results, retrying\n")
       return VMCommand.execute(vm, cmd, options)
     end
   end