bugfix: olsrd-watchdog false triggers a reboot.

Using the method suggested by Henning Rogge in 2014

{{{
1) remove file
2) wait 2 intervals
3) if file exists, go to 1)
4) restart olsr, then go to 1)
}}}

With the exception that we currently wait more than 2 intervals.

Even if the script hits a collision at the same time the file is being written the file will already exist from one of the previous writes or the current write.

Removing a file in use is safe as once the FD closes the file contents are fully released.

Additional Advantages:
* Should be more efficient to check if file exists instead of reading the file and comparing date stamps.
* Removing the Perl code moves us one step closer to retiring Perl in the future.

files/usr/local/bin/olsrd-watchdog

@@ -1,31 +1,28 @@
-#!/usr/bin/perl
+#!/bin/sh
 
-# wait for the watchdog file to appear
-while(not -e "/tmp/olsrd.watchdog") { sleep 15 }
-  
-$failcount = 0;
-$last_olsrstamp = 0;
+# wait for the watchdog file to appear before starting
+while [ ! -f "/tmp/olsrd.watchdog" ]
+do
+  sleep 15
+done
 
 
-while(1)
-{
-  chomp ($olsr = `cat /tmp/olsrd.watchdog`);
+while true
+do
 
-  if ( $olsr && $olsr ne $last_olsrstamp ){
-    $failcount = 0;
-  } else {
-    $failcount += 1;
-  }
-    
-  if( $failcount >= 3 )
-  {
-    ($uptime) = `cat /proc/uptime` =~ /^(\d+)/;
-    $date = `date`;
-    system qq(echo -n "$uptime $date" >> /tmp/olsrd.log);
-    system "/etc/init.d/olsrd restart";
-  }
+  if [ -f "/tmp/olsrd.watchdog" ]
+  then
+    rm -f "/tmp/olsrd.watchdog"
+  else
+    uptime=`cat /proc/uptime | cut -d' ' -f1`
+    date=`date`
+    echo "$uptime $date" >> /tmp/olsrd.log
+    /etc/init.d/olsrd restart
+  fi
 
-  $last_olsrstamp = $olsr;
+  # With interval of 5 seconds this gives ~3 chances
+  # for a file write before next loop.
+  sleep 15
+
+done
 
-  sleep 10;
-}