Introduce "Base" module

This module just contains some basic functions of guardian.

Signed-off-by: Stefan Schantl <stefan.schantl@ipfire.org>

diff --git a/modules/Base.pm b/modules/Base.pm
new file mode 100644 (file)
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;