From: Stefan Schantl <stefan.schantl@ipfire.org>
Date: Fri, 20 Nov 2015 14:23:56 +0000 (+0100)
Subject: Add "Logger" module.
X-Git-Tag: 2.0~82
X-Git-Url: http://git.ipfire.org/?p=people%2Fstevee%2Fguardian.git;a=commitdiff_plain;h=a17e021e8a637d06f0758d426dc0931610e30197

Add "Logger" module.

This module is responsible for logging any messages which are generated by
guaridan or one of its submodules during runtime and displays them on the
console or send them to the syslog.

When using the logger module, it has to be initialized as an object, which calls the
"New" function and requires the following settings:

* LogLevel - which has to be "off, err, info or debug"
* LogFacility - which currently supports "console or syslog"

After that, logging can be done, by using the "Log" function on the object, by providing
the type of the message (LogLevel) and the message self.

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

diff --git a/modules/Logger.pm b/modules/Logger.pm
new file mode 100644
index 0000000..a29d078
--- /dev/null
+++ b/modules/Logger.pm
@@ -0,0 +1,148 @@
+package Guardian::Logger;
+use strict;
+use warnings;
+
+use Exporter qw(import);
+
+our @EXPORT_OK = qw(New Log GetLogLevels);
+
+use Sys::Syslog qw(:DEFAULT setlogsock);
+
+# Hash which stores all supported log levels and their priority.
+my %loglevels = (
+	'off' => '0',
+	'err' => '1',
+	'info' => '1',
+	'debug' => '2',
+);
+
+# This hash contains the supported log facilities and their corresponding subroutines.
+my %logfacilities = (
+	"console" => \&LogFacilityConsole,
+	"syslog" => \&LogFacilitySyslog,
+);
+
+
+#
+## The "New" (Logger) function.
+#
+## This function is responsible to initialize the Logger as a class based object.
+## It has to be called once before logging can be done.
+#
+## The following arguments must be passed, when initializing a new Logger:
+## "LogLevel" and "LogFacility" with valid values from above.
+#
+sub New (%) {
+	my ( $class, %args ) = @_;
+	my $self = \%args;
+
+	# Fail, if some critical arguments are missing.
+	unless ((exists($self->{LogLevel})) && (exists($self->{LogFacility}))) {
+		die "Could not initialize the Logger: Too less arguments are given.\n";
+	}
+
+	# Use bless to make "$self" to an object of class "$class".
+	bless($self, $class);
+
+	# Return the class object.
+	return $self;
+}
+
+#
+## The main "Log" function.
+#
+## This function is used to handle the messages which are generated on various 
+## points in the main programm or its modules. Those messages will contain usefull
+## information or deeper details about errors.
+#
+## The Log function takes care about the configured loglevel and transmitts the
+## log messages to the configured log facility.
+#
+sub Log ($$) {
+	my $self = shift;
+	my ($level, $message) = @_;
+
+	# Check if we got an invalid loglevel.
+	unless(exists($loglevels{$level})) {
+                &Log("err", "The logger has been called with an invalid loglevel ($level)!\n");
+                return;
+        }
+
+	# Get value for the current used loglevel.
+	my $current_level = $loglevels{$self->{LogLevel}};
+
+	# Get value for the required loglevel.
+	my $required_level = $loglevels{$level};
+
+	# Compare the current and required level to determine,
+	# if the message should be handled.
+	if ($current_level >= $required_level) {
+		# Get the facility, which should be used.
+		my $use_facility = $self->{LogFacility};
+
+		# Transmit log message to the correct log facility.
+		$logfacilities{$use_facility}->($level, $message);
+	}
+}
+
+#
+## The Update (Logger) settings function
+#
+## This function is used to update the object settings of the
+## initialized Logger class.
+#
+sub Update (%) {
+	my ($self, %args) = @_;
+
+	# Map the new hash keys and values to the existing one inside
+	# the class.
+	map { $self->{ $_ } = $args{ $_ } } keys %args;
+}
+
+#
+## GetLogLevels function.
+#
+## This really simple function just returns the hash which
+## contains all supported log levels.
+#
+sub LogLevels () {
+	# Nothing to do, just return the loglevels hash.
+	return %loglevels;
+}
+
+#
+## LogFacilityConsole function.
+#
+## This is a very simple log facility which just prints the given log
+## message to STDOUT.
+#
+sub LogFacilityConsole ($$) {
+	my ($type, $message) = @_;
+
+	# Print message on STDOUT.
+	print STDOUT "\[$type\] $message\n";
+}
+
+#
+## LogFacilitySyslog function.
+#
+## This log facility sends a given log message to the system log service (syslog).
+#
+sub LogFacilitySyslog ($$) {
+	my ($type, $message) = @_;
+
+	# The syslog function works best with an array based input,
+	# so generate one before passing the message details to syslog.
+	my @syslog = ("$type", "<$type> $message");
+
+	# Establish the connection to the syslog service.
+	openlog('guardian', 'cons,pid', 'user');
+
+	# Send the log message.
+	syslog(@syslog);
+
+	# Close the log handle.
+	closelog();
+}
+
+1;