modules/Logger.pm

   1 package Guardian::Logger;
   2 use strict;
   3 use warnings;
   4
   5 use Exporter qw(import);
   6
   7 our @EXPORT_OK = qw(New Log GetLogLevels);
   8
   9 use Sys::Syslog qw(:DEFAULT setlogsock);
  10
  11 # Hash which stores all supported log levels and their priority.
  12 my %loglevels = (
  13         'off' => '0',
  14         'err' => '1',
  15         'info' => '1',
  16         'debug' => '2',
  17 );
  18
  19 # This hash contains the supported log facilities and their corresponding subroutines.
  20 my %logfacilities = (
  21         "console" => \&LogFacilityConsole,
  22         "file" => \&LogFacilityFile,
  23         "syslog" => \&LogFacilitySyslog,
  24 );
  25
  26
  27 #
  28 ## The "Init" (Logger) function.
  29 #
  30 ## This function is responsible to initialize the Logger as a class based object.
  31 ## It has to be called once before logging can be done.
  32 #
  33 ## The following arguments must be passed, when initializing a new Logger:
  34 ## "LogLevel" and "LogFacility" with valid values from above.
  35 #
  36 sub Init (%) {
  37         my ( $class, %args ) = @_;
  38         my $self = \%args;
  39
  40         # Fail, if some critical arguments are missing.
  41         unless ((exists($self->{LogLevel})) && (exists($self->{LogFacility}))) {
  42                 die "Could not initialize the Logger: Too less arguments are given.\n";
  43         }
  44
  45         # Use bless to make "$self" to an object of class "$class".
  46         bless($self, $class);
  47
  48         # Return the class object.
  49         return $self;
  50 }
  51
  52 #
  53 ## The main "Log" function.
  54 #
  55 ## This function is used to handle the messages which are generated on various
  56 ## points in the main programm or its modules. Those messages will contain usefull
  57 ## information or deeper details about errors.
  58 #
  59 ## The Log function takes care about the configured loglevel and transmitts the
  60 ## log messages to the configured log facility.
  61 #
  62 sub Log ($$) {
  63         my $self = shift;
  64         my ($level, $message) = @_;
  65
  66         # Check if we got an invalid loglevel.
  67         unless(exists($loglevels{$level})) {
  68                 &Log("err", "The logger has been called with an invalid loglevel ($level)!\n");
  69                 return;
  70         }
  71
  72         # Get value for the current used loglevel.
  73         my $current_level = $loglevels{$self->{LogLevel}};
  74
  75         # Get value for the required loglevel.
  76         my $required_level = $loglevels{$level};
  77
  78         # Compare the current and required level to determine,
  79         # if the message should be handled.
  80         if ($current_level >= $required_level) {
  81                 # Get the facility, which should be used.
  82                 my $use_facility = $self->{LogFacility};
  83
  84                 # Transmit log message to the correct log facility.
  85                 $logfacilities{$use_facility}->($self, $level, $message);
  86         }
  87 }
  88
  89 #
  90 ## GetLogLevels function.
  91 #
  92 ## This really simple function just returns the hash which
  93 ## contains all supported log levels.
  94 #
  95 sub GetLogLevels () {
  96         # Nothing to do, just return the loglevels hash.
  97         return %loglevels;
  98 }
  99
 100 #
 101 ## LogFacilityConsole function.
 102 #
 103 ## This is a very simple log facility which just prints the given log
 104 ## message to STDOUT.
 105 #
 106 sub LogFacilityConsole ($$) {
 107         my $self = shift;
 108         my ($type, $message) = @_;
 109
 110         # Print message on STDOUT.
 111         print STDOUT "\[$type\] $message\n";
 112 }
 113
 114 #
 115 ## LogFacilitySyslog function.
 116 #
 117 ## This log facility sends a given log message to the system log service (syslog).
 118 #
 119 sub LogFacilitySyslog ($$) {
 120         my $self = shift;
 121         my ($type, $message) = @_;
 122
 123         # The syslog function works best with an array based input,
 124         # so generate one before passing the message details to syslog.
 125         my @syslog = ("$type", "<$type> $message");
 126
 127         # Establish the connection to the syslog service.
 128         openlog('guardian', 'cons,pid', 'user');
 129
 130         # Send the log message.
 131         syslog(@syslog);
 132
 133         # Close the log handle.
 134         closelog();
 135 }
 136
 137 #
 138 ## LogFacilityFile function.
 139 #
 140 ## This log facility will write any given log messages to a specified log file.
 141 #
 142 sub LogFacilityFile ($$) {
 143         my $self = shift;
 144         my ($type, $message) = @_;
 145
 146         # Open the logfile for writing.
 147         open(LOGFILE, '>>', $self->{LogFile}) or die "Could not write to $self->{LogFile}: $!\n";
 148
 149         # Write log message to file.
 150         print LOGFILE "\[$type\] $message\n";
 151
 152         # Close filehandle.
 153         close(FILE);
 154 }
 155
 156 1;