From 1e736116d2aad179f5bb11ddb40d5d810e758f0c Mon Sep 17 00:00:00 2001
From: Stefan Schantl <stefan.schantl@ipfire.org>
Date: Wed, 25 Nov 2015 09:04:55 +0100
Subject: [PATCH] Introduce "Base" module

This module just contains some basic functions of guardian.

Signed-off-by: Stefan Schantl <stefan.schantl@ipfire.org>
---
 modules/Base.pm | 89 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)
 create mode 100644 modules/Base.pm

diff --git a/modules/Base.pm b/modules/Base.pm
new file mode 100644
index 0000000..e4ff8a0
--- /dev/null
+++ b/modules/Base.pm
@@ -0,0 +1,89 @@
+package Guardian::Base;
+use strict;
+use warnings;
+
+use Exporter qw(import);
+
+our @EXPORT_OK = qw(GenerateMonitoredFiles);
+
+#
+## Function for fileposition initialization.
+#
+## This function is used to get the cursor position of the end of file (EOF) of
+## a specified file.
+#
+## In order to prevent from permanently read and keep files opened, or dealing
+## with huge logfiles, at initialization time of the worker processes, the file will
+## be opened once and the cursor position of the end of file (EOF) get stored.
+#
+sub InitFileposition ($) {
+	my $file = $_[0];
+
+	# Open the file.
+	open(FILE, $file) or die "Could not open $file. $!\n";
+
+	# Just seek to the end of the file (EOF).
+	seek(FILE, 0, 2);
+
+	# Get and store the position.
+	my $position = tell(FILE),
+
+	# Close the file again.
+	close(FILE);
+
+	# Return the position.
+	return $position;
+}
+
+#
+## Function to generate a hash of monitored files and their file positions.
+#
+## This function is responsible for creating the hash of which files should be
+## monitored by guardian. In order to do this, all options from the given hash of
+## main settings will be parsed and all files to monitor extracted and stored into
+## a temporary hash.
+#
+## Next step will be to check if the the file allready is part of the existing hash
+## of monitored files and if true to use the stored value of the current cursor position.
+## If this check fails, the responsible function to initialize the cursor position of
+## EOF (end of file) will be called and stored.
+#
+sub GenerateMonitoredFiles (\%\%) {
+	# Dereference the given hash-refs and store
+	# them into a new temporary hashes.
+	my %mainsettings = %{ $_[0] };
+	my %current_monitored_files = %{ $_[1] };
+
+	# Private hash for storing the new monitored files.
+	my %new_monitored_files = ();
+
+	# Loop through the temporary hash which contains the main settings
+	# and search for files which should be monitored. Compare if the file
+	# already was part of the Add them to the
+	# private new hash of monitored files which will be returned.
+        foreach my $config_option (keys %mainsettings) {
+                # Skip option if it does not look like "Monitor_XYZ".
+                next unless($config_option =~ m/^Monitor_/);
+
+                # Get the configured file for this option.
+                my $file = $mainsettings{$config_option};
+
+                # Skip the file, if it does not exist or is not read-able.
+                next unless(-r "$file");
+
+                # Check if the file not yet has been added to the hash
+                # of monitored files.
+                unless(exists($current_monitored_files{$file})) {
+                        # Add the file, init and store the fileposition.
+                        $new_monitored_files{$file} = &InitFileposition($file);
+                } else {
+			# Add the file and grab the fileposition from the existing hash.
+			$new_monitored_files{$file} = $current_monitored_files{$file};
+		}
+        }
+
+	# Return the new_monitored_files hash.
+	return %new_monitored_files;
+}
+
+1;
-- 
2.39.2