Improve loading of configuration file

If the configuration file was placed in the same directory as the script, the script would fail if launched from any other directory because the configuration file name was defined without a path.

This patch improves the script so that it will load the configuration file from either the same directory as the script, or from /etc.

I also moved the initialization of $pid and $cid to the top of the script because the fact that they were uninitialized was preventing the script from reporting the configuration file error properly.

sqm-autorate.pl

@@ -208,12 +208,20 @@
 my %reflector_offsets      :shared;    # Time offset for each ICMP reflector
 my %reflector_minimum_rtts :shared;    # Minimum RTT time seen for each ICMP reflector (used when calculating the offset)
 
+# Initialise the process ID and cycle ID
+$pid = "$$";
+$cid = sprintf("%010d", 0);
+
 #######################################################################################
 # Configuration
 #######################################################################################
 
 # Read the configuration properties file and use them to populate global variables
-my $config_file = "sqm-autorate.conf";
+# Configuration file can be located in the same directory as the script, or /etc
+my $config_file = substr($0, 0, rindex($0, "/")) . "/sqm-autorate.conf";
+if (! -e $config_file) {
+	$config_file = "/etc/sqm-autorate.conf";
+}
 my %config_properties = &get_config_properties($config_file);
 
 # Upload interfaces
@@ -386,14 +394,6 @@
 STDOUT->autoflush(1);
 STDERR->autoflush(1);
 
-# Initialise the process ID and cycle ID
-{
-	lock($pid);
-	lock($cid);
-	$pid = "$$";
-	$cid = sprintf("%010d", 0);
-}
-
 # Process command line arguments
 &process_args();