[Patch[ xl problems with xendomains

[Ian Murray <murrayie@yahoo.co.uk>]

Hi,

Ever since xl become the preferred toolstack, I have had problems using 
the xendomains startup/shutdown script.  Having retested today, it seems 
that the issues are now reduced down to xendomains being unable to 
restart previously saved domains.

Here is a typical session using xl running Xen 4.2.2 on Ubuntu 64 12.04 
bit server, using stock Dom0 kernel (3.2.0-43-generic)

root@xen6:/etc/init.d# service xendomains start
root@xen6:/etc/init.d# service xendomains stop
Shutting down Xen domains: *   [done]
root@xen6:/etc/init.d# xl create /etc/xen/vpn2
Parsing config from /etc/xen/vpn2
Daemon running with PID 3969
root@xen6:/etc/init.d# service xendomains start
root@xen6:/etc/init.d# service xendomains stop
Shutting down Xen domains: vpn2(save)....
  *   [done]
root@xen6:/etc/init.d# service xendomains start
Restoring Xen domains:/etc/init.d/xendomains: line 258: [: too many 
arguments

  *   [done]
root@xen6:/# rm /var/lib/xen/save/vpn2

Line 258 reads as:-

-                if [ $HEADER = "LinuxGuestRecord" ]; then

There were further issues of xendomains not suspending domains properly 
but this appear resolved now because I think the behaviour of xl list -l 
has changed. AFAIR an extra 'domain' identifier was thrown in which was 
causing issues with the regex parser.

Anyway, as far as I can tell, the two issues that I see are that the if 
statement at line 258 borks because there are no quotes around the 
$HEADER. I'll leave it to the Bash gurus to explain that; I am not one 
and I just hacked it to work.

Secondly, it would appear that when using xl to save a running domain, 
the header in the save file does not contain the text "LinuxGuestRecord" 
but in fact contains "Xen saved domain". This causes xendomains to miss 
the save files and will not try to restore them. Placing a simple 
variable that contains the correct header text appears to fix this.

So applying the following patch to xendomains appears to ease these 
issues. Please be aware that I haven't tested this on anything earlier 
than 4.2.2 and hasn't been tested at all using xm, although the issues 
with the regex would likely break xm rather than the change below. 
Looking back at my original submission (2 years ago), I reported the 
issues against 4.1.1. As previously stated this had more problems 
because of differing output of xl list -l, which appears to be employed 
by xendomains. I haven't thoroughly tested the patch against every 
combination of domains sysreq'd, etc, but it appears to work for auto 
start, save and restore.

Thanks for reading and I hope this makes sense,

Ian.


Signed-off-by: Ian MURRAY <murrayie@yahoo.co.uk>

--- xendomains.422.orig 2013-05-19 18:06:18.525195879 +0100
+++ xendomains  2013-05-21 21:27:57.253429073 +0100
@@ -28,10 +28,12 @@
  ### END INIT INFO

  CMD=xm
++HEADCOMP="LinuxGuestRecord"
  $CMD list &> /dev/null
  if test $? -ne 0
  then
         CMD=xl
+       HEADCOMP="Xen saved domain"
  fi

  $CMD list &> /dev/null
@@ -255,7 +257,7 @@
          for dom in $XENDOMAINS_SAVE/*; do
              if [ -f $dom ] ; then
                  HEADER=`head -c 16 $dom | head -n 1 2> /dev/null`
-                if [ $HEADER = "LinuxGuestRecord" ]; then
+                if [ "$HEADER" = "$HEADCOMP" ]; then
                      echo -n " ${dom##*/}"
                      XMR=`$CMD restore $dom 2>&1 1>/dev/null`
                      #$CMD restore $dom