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 use POSIX qw(strftime);
  11
  12 # Hash which stores all supported log levels and their priority.
  13 my %loglevels = (
  14         'off' => '0',
  15         'err' => '1',
  16         'info' => '1',
  17         'debug' => '2',
  18 );
  19
  20 # This hash contains the supported log facilities and their corresponding subroutines.
  21 my %logfacilities = (
  22         "console" => \&LogFacilityConsole,
  23         "file" => \&LogFacilityFile,
  24         "syslog" => \&LogFacilitySyslog,
  25 );
  26
  27
  28 #
  29 ## The "Init" (Logger) function.
  30 #
  31 ## This function is responsible to initialize the Logger as a class based object.
  32 ## It has to be called once before logging can be done.
  33 #
  34 ## The following arguments must be passed, when initializing a new Logger:
  35 ## "LogLevel" and "LogFacility" with valid values from above.
  36 #
  37 sub Init (%) {
  38         my ( $class, %args ) = @_;
  39         my $self = \%args;
  40
  41         # Fail, if some critical arguments are missing.
  42         unless ((exists($self->{LogLevel})) && (exists($self->{LogFacility}))) {
  43                 die "Could not initialize the Logger: Too less arguments are given.\n";
  44         }
  45
  46         # Use bless to make "$self" to an object of class "$class".
  47         bless($self, $class);
  48
  49         # Return the class object.
  50         return $self;
  51 }
  52
  53 #
  54 ## The main "Log" function.
  55 #
  56 ## This function is used to handle the messages which are generated on various
  57 ## points in the main programm or its modules. Those messages will contain usefull
  58 ## information or deeper details about errors.
  59 #
  60 ## The Log function takes care about the configured loglevel and transmitts the
  61 ## log messages to the configured log facility.
  62 #
  63 sub Log ($$) {
  64         my $self = shift;
  65         my ($level, $message) = @_;
  66
  67         # Check if we got an invalid loglevel.
  68         unless(exists($loglevels{$level})) {
  69                 &Log("err", "The logger has been called with an invalid loglevel ($level)!\n");
  70                 return;
  71         }
  72
  73         # Get value for the current used loglevel.
  74         my $current_level = $loglevels{$self->{LogLevel}};
  75
  76         # Get value for the required loglevel.
  77         my $required_level = $loglevels{$level};
  78
  79         # Compare the current and required level to determine,
  80         # if the message should be handled.
  81         if ($current_level >= $required_level) {
  82                 # Get the facility, which should be used.
  83                 my $use_facility = $self->{LogFacility};
  84
  85                 # Transmit log message to the correct log facility.
  86                 $logfacilities{$use_facility}->($self, $level, $message);
  87         }
  88 }
  89
  90 #
  91 ## GetLogLevels function.
  92 #
  93 ## This really simple function just returns the hash which
  94 ## contains all supported log levels.
  95 #
  96 sub GetLogLevels () {
  97         # Nothing to do, just return the loglevels hash.
  98         return %loglevels;
  99 }
 100
 101 #
 102 ## LogFacilityConsole function.
 103 #
 104 ## This is a very simple log facility which just prints the given log
 105 ## message to STDOUT.
 106 #
 107 sub LogFacilityConsole ($$) {
 108         my $self = shift;
 109         my ($type, $message) = @_;
 110
 111         # Get current date and time and format like: "Jan 01 00:00:01"
 112         my $now = strftime "%b %e %H:%M:%S", localtime();
 113
 114         # Print message on STDOUT.
 115         print STDOUT "$now \[$type\] $message\n";
 116 }
 117
 118 #
 119 ## LogFacilitySyslog function.
 120 #
 121 ## This log facility sends a given log message to the system log service (syslog).
 122 #
 123 sub LogFacilitySyslog ($$) {
 124         my $self = shift;
 125         my ($type, $message) = @_;
 126
 127         # The syslog function works best with an array based input,
 128         # so generate one before passing the message details to syslog.
 129         my @syslog = ("$type", "<$type> $message");
 130
 131         # Establish the connection to the syslog service.
 132         openlog('guardian', 'cons,pid', 'user');
 133
 134         # Send the log message.
 135         syslog(@syslog);
 136
 137         # Close the log handle.
 138         closelog();
 139 }
 140
 141 #
 142 ## LogFacilityFile function.
 143 #
 144 ## This log facility will write any given log messages to a specified log file.
 145 #
 146 sub LogFacilityFile ($$) {
 147         my $self = shift;
 148         my ($type, $message) = @_;
 149
 150         # Get current date and time and format like: "Jan 01 00:00:01"
 151         my $now = strftime "%b %e %H:%M:%S", localtime();
 152
 153         # Open the logfile for writing.
 154         open(LOGFILE, '>>', $self->{LogFile}) or die "Could not write to $self->{LogFile}: $!\n";
 155
 156         # Write log message to file.
 157         print LOGFILE "$now \[$type\] $message\n";
 158
 159         # Close filehandle.
 160         close(FILE);
 161 }
 162
 163 1;