modules/Base.pm

   1 package Guardian::Base;
   2 use strict;
   3 use warnings;
   4
   5 use Exporter qw(import);
   6
   7 our @EXPORT_OK = qw(GenerateMonitoredFiles);
   8
   9 #
  10 ## Function for fileposition initialization.
  11 #
  12 ## This function is used to get the cursor position of the end of file (EOF) of
  13 ## a specified file.
  14 #
  15 ## In order to prevent from permanently read and keep files opened, or dealing
  16 ## with huge logfiles, at initialization time of the worker processes, the file will
  17 ## be opened once and the cursor position of the end of file (EOF) get stored.
  18 #
  19 sub InitFileposition ($) {
  20         my $file = $_[0];
  21
  22         # Open the file.
  23         open(FILE, $file) or die "Could not open $file. $!\n";
  24
  25         # Just seek to the end of the file (EOF).
  26         seek(FILE, 0, 2);
  27
  28         # Get and store the position.
  29         my $position = tell(FILE),
  30
  31         # Close the file again.
  32         close(FILE);
  33
  34         # Return the position.
  35         return $position;
  36 }
  37
  38 #
  39 ## Function to generate a hash of monitored files and their file positions.
  40 #
  41 ## This function is responsible for creating the hash of which files should be
  42 ## monitored by guardian. In order to do this, all options from the given hash of
  43 ## main settings will be parsed and all files to monitor extracted and stored into
  44 ## a temporary hash.
  45 #
  46 ## Next step will be to check if the the file allready is part of the existing hash
  47 ## of monitored files and if true to use the stored value of the current cursor position.
  48 ## If this check fails, the responsible function to initialize the cursor position of
  49 ## EOF (end of file) will be called and stored.
  50 #
  51 sub GenerateMonitoredFiles (\%\%) {
  52         # Dereference the given hash-refs and store
  53         # them into a new temporary hashes.
  54         my %mainsettings = %{ $_[0] };
  55         my %current_monitored_files = %{ $_[1] };
  56
  57         # Private hash for storing the new monitored files.
  58         my %new_monitored_files = ();
  59
  60         # Loop through the temporary hash which contains the main settings
  61         # and search for files which should be monitored. Compare if the file
  62         # already was part of the Add them to the
  63         # private new hash of monitored files which will be returned.
  64         foreach my $config_option (keys %mainsettings) {
  65                 # Skip option if it does not look like "Monitor_XYZ".
  66                 next unless($config_option =~ m/^Monitor_/);
  67
  68                 # Get the configured file for this option.
  69                 my $file = $mainsettings{$config_option};
  70
  71                 # Skip the file, if it does not exist or is not read-able.
  72                 next unless(-r "$file");
  73
  74                 # Check if the file not yet has been added to the hash
  75                 # of monitored files.
  76                 unless(exists($current_monitored_files{$file})) {
  77                         # Add the file, init and store the fileposition.
  78                         $new_monitored_files{$file} = &InitFileposition($file);
  79                 } else {
  80                         # Add the file and grab the fileposition from the existing hash.
  81                         $new_monitored_files{$file} = $current_monitored_files{$file};
  82                 }
  83         }
  84
  85         # Return the new_monitored_files hash.
  86         return %new_monitored_files;
  87 }
  88
  89 1;