#!/usr/bin/perl -w
#######################################################################################
# monitorDiskUsage.pl
# Written by: Brandon Zehm <caspian_@hotmail.com>
# 
# Purpose:
#   To monitor the output of 'df' and send information
#   to the system log.
#
# Technical Description:
#   Runs a `df` and parses the output.  Then it calls
#   /usr/local/bin/syslog.pl (written by me) to print
#   results to the syslog server.
#
# Changelog:
#     01/20/2004 - v1.20
#         - Require a -r option to run.
#         - Added a -l option for logging to a file
#         - Textual changes to most error messages.
#
#######################################################################################
use strict;

## Global Variable(s)
my %conf = (
    "programName"          => "monitorDiskUsage.pl",
    "version"              => "1.20",
    "authorName"           => "Brandon Zehm",                    ## Information about the author or owner of this script.
    "authorEmail"          => "caspian\@dotconf.net",
    "hostname"             => $ENV{'HOSTNAME'},                  ## Used in printmsg() for all output.
    
    "syslogProgram"        => "/usr/local/bin/syslog.pl",
    
    "run"                  => 0,                                 ## Whether we should run script or not
    "debug"                => 0,
    "syslog"               => 1,                                 ## Syslog messages by default (--stdout disables this)
    "stdout"               => 0,
    "facility"             => "USER",
    "priority"             => "INFO",
    "logging"              => '',                                ## If this is true the printmsg function prints to the log file
    "logFile"              => '',                                ## If this is specified (form the command line via -l) this file will be used for logging.
    
    ## Set some thresholds, this just changes the message printed and the syslog priority.
    "thresholdWARNING"     => 75,
    "thresholdERROR"       => 90,
    "thresholdCRIT"        => 95,
    "thresholdEMERG"       => 99,
);







#############################
##
##      MAIN PROGRAM
##
#############################

## Initialize
initialize();

## Process Command Line
processCommandLine();

## Open the log file if we need to
if ($conf{'logFile'}) {
    if ($conf{'logging'}) {
        $conf{'logging'} = 0;
        close LOGFILE;
    }
    if (openLogFile($conf{'logFile'})) { quit("OS-ERROR => Opening the log file [$conf{'logFile'}] returned the error: $!", 1); }
}

## Get list of mounted volumes (and useage report)
my @df = `/bin/df`;

## For each volume check its usage
foreach (@df) {
    next if ($_ =~ /Filesystem/i);    ## Skip to the next line if this one is the first line.
    next if ( $_ !~ /\%/);            ## Skip to the next line if this one doesn't have a % symbol.
    my %info = ();
    
    ## Extract info from df's printout
    (
      $info{'device'},
      $info{'size'},
      $info{'used'},
      $info{'avail'},
      $info{'use'},
      $info{'mount'},
    ) = split(/\s+/, $_);
    $info{'use'} =~ s/\%//;
    
    ## Decide how urgent this is:
          
    ## EMERGENCY ##
    if ( $info{'use'} >= $conf{'thresholdEMERG'}) {
        $conf{'priority'} = "EMERG";
    } 
  
    ## CRIT ##
    elsif ( $info{'use'} >= $conf{'thresholdCRIT'} ) {
        $conf{'priority'} = "CRIT";
    } 
    
    ## ERROR ##
    elsif ( $info{'use'} >= $conf{'thresholdERROR'} ) {
        $conf{'priority'} = "ERR";
    }
    
    ## WARNING ##
    elsif ( $info{'use'} >= $conf{'thresholdWARNING'} ) {
        $conf{'priority'} = "WARNING";
    }
    
    else {
      $conf{'priority'} = "INFO";
    }
    
    ## Generate an output message
    printmsg("OS-$conf{'priority'} => Mount [$info{'mount'}] is [$info{'use'}\%] full, with [$info{'avail'} KB] free.", 0);
}

## Quit
quit("",0);
































######################################################################
## Function:    help ()
##
## Description: For all those newbies ;) 
##              Prints a help message and exits the program.
## 
######################################################################
sub help {
print <<EOM;

$conf{'programName'}-$conf{'version'} by $conf{'authorName'} <$conf{'authorEmail'}>

Checks disk space usage on all mounted volumes.  The system syslog 
is used for any generated messages unless the --stdout option is used.
  
Usage:  $conf{'programName'} [options]

  Required:
    -r                        run script
  
  Optional:
    --stdout                  print messages to STDOUT rather than the syslog.
    --facility=[0-11]         syslog facility (1/USER is used by default)
    -l <logfile>              enable logging to the specified file
    -v                        verbosity - use multiple times for greater effect

EOM
quit("", 1);
}










######################################################################
##  Function: initialize ()
##  
##  Does all the script startup jibberish.
##  
######################################################################
sub initialize {

    ## Set STDOUT to flush immediatly after each print  
    $| = 1;

    ## Intercept signals
    $SIG{'QUIT'}  = sub { quit("$$ - EXITING: Received SIG$_[0]", 1); };
    $SIG{'INT'}   = sub { quit("$$ - EXITING: Received SIG$_[0]", 1); };
    $SIG{'KILL'}  = sub { quit("$$ - EXITING: Received SIG$_[0]", 1); };
    $SIG{'TERM'}  = sub { quit("$$ - EXITING: Received SIG$_[0]", 1); };
  
    ## ALARM and HUP signals are not supported in Win32
    unless ($^O =~ /win/i) {
        $SIG{'HUP'}   = sub { quit("$$ - EXITING: Received SIG$_[0]", 1); };
        $SIG{'ALRM'}  = sub { quit("$$ - EXITING: Received SIG$_[0]", 1); };
    }
  
    ## Make sure the path is sane
    $ENV{'PATH'} .= ":/bin:/usr/bin:/usr/local/bin:/sbin:/usr/sbin:/usr/local/sbin";
  
    ## Fixup $conf{'hostname'}
    if ($conf{'hostname'}) {
        $conf{'hostname'} = $conf{'hostname'};
        $conf{'hostname'} =~ s/\..*$//;
    }
    else {
        $conf{'hostname'} = "unknown";
    }
  
    return(1);
}









######################################################################
##  Function: processCommandLine ()
##  
##  Processes command line storing important data in global var %conf
##  
######################################################################
sub processCommandLine {
  
    ############################
    ##  Process command line  ##
    ############################
  
    my @ARGS = @ARGV;
    my $numargv = @ARGS;
    my $counter = 0;
    for ($counter = 0; $counter < $numargv; $counter++) {
    
        if ($ARGS[$counter] =~ s/^--stdout//i) {             ## stdout ##
            $conf{'stdout'} = 1;
            $conf{'syslog'} = 0;
        }
    
        elsif ($ARGS[$counter] =~ s/^--facility=//i) {       ## Facility ##
            $conf{'facility'} = $';
        }

        elsif ($ARGS[$counter] =~ /^-r$/) {                  ## Run
            $conf{'run'} = 1;
        }
        
        elsif ($ARGS[$counter] =~ /^-l$/) {                  ## Log File ##
            $counter++;
            $conf{'logFile'} = $ARGS[$counter];
        }
        
        elsif ($ARGS[$counter] =~ s/^-v+//i) {               ## Verbosity ##
            $conf{'debug'} += (length($&) - 1);
        }
        
        elsif ($ARGS[$counter] =~ /^-h$|help/i) {            ## Help ##
            help();
        }
        
        else {                                               ## Unknown option ##
            quit("The option [$ARGS[$counter]] is not understood! Try --help.", 1);
        }

    }
  
    ## If the user didn't use a -r print the help
    if ($conf{'run'} == 0) {
        help();
    }
    
    return(1);
}











###############################################################################################
##  Function:    printmsg (string $message, int $level)
##
##  Description: Handles all messages - 
##               Depending on the state of the program it will log
##               messages to a log file, print them to STDOUT or both.
##               
##
##  Input:       $message          A message to be printed, logged, etc.
##               $level            The debug level of the message. If not defined 0
##                                 will be assumed.  0 is considered a normal message, 
##                                 1 and higher is considered a debug message.
##  
##  Output:      Prints to STDOUT, to LOGFILE, both, or none depending 
##               on the state of the program and the debug level specified.
##  
##  Example:     printmsg("ERROR => The file could not be opened!", 0);
###############################################################################################
sub printmsg {
    ## Assign incoming parameters to variables
    my ( $message, $level ) = @_;
    
    ## Make sure input is sane
    $level = 0 if (!defined($level));
    
    ## Continue only if the debug level of the program is >= message debug level.
    if ($conf{'debug'} >= $level) {
        
        ## Get the date in the format: Dec  3 11:14:04
        my ($sec, $min, $hour, $mday, $mon) = localtime();
        $mon = ('Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec')[$mon];
        my $date = sprintf("%s %02d %02d:%02d:%02d", $mon, $mday, $hour, $min, $sec);
    
        ## Syslog the message is needed
        if ($conf{'syslog'}) {
            system( qq{$conf{'syslogProgram'} --facility=$conf{'facility'} --priority=$conf{'priority'} "$conf{'programName'}: $message" });
        }
        
        ## Print to STDOUT always if debugging is enabled, or if conf{stdout} is true.
        if ( ($conf{'debug'} >= 1) or ($conf{'stdout'} == 1) ) {
            print "$date $conf{'hostname'} $conf{'programName'}: $message\n";
        }
        
        ## Print to the log file if $conf{'logging'} is true
        if ($conf{'logging'}) {
            print LOGFILE "$date $conf{'hostname'} $conf{'programName'}: $message\n";
        }
        
    }
    
    ## Return 0 errors
    return(0);
}














###############################################################################################
## FUNCTION:    
##   openLogFile ( $filename )
## 
## 
## DESCRIPTION: 
##   Opens the file $filename and attaches it to the filehandle "LOGFILE".  Returns 0 on success
##   and non-zero on failure.  Error codes are listed below, and the error message gets set in
##   global variable $!.
##   
##   
## Example: 
##   openFile ("/var/log/scanAlert.log");
##
###############################################################################################
sub openLogFile {
    ## Get the incoming filename
    my $filename = $_[0];
    
    ## Make sure our file exists, and if the file doesn't exist then create it
    if ( ! -f $filename ) {
        printmsg("NOTICE => The file [$filename] does not exist.  Creating it now with mode [0600].", 0);
        open (LOGFILE, ">>$filename");
        close LOGFILE;
        chmod (0600, $filename);
    }
    
    ## Now open the file and attach it to a filehandle
    open (LOGFILE,">>$filename") or return (1);
    
    ## Put the file into non-buffering mode
    select LOGFILE;
    $| = 1;
    select STDOUT;
    
    ## Tell the rest of the program that we can log now
    $conf{'logging'} = "yes";
    
    ## Return success
    return(0);
}











#####################################################################
##  Function:    quit (string $message, int $errorLevel)
##  
##  Description: Exits the program, optionally printing $message.  It 
##               returns an exit error level of $errorLevel to the 
##               system  (0 means no errors, and is assumed if empty.)
##
##  Example:     quit("Exiting program normally", 0);
######################################################################
sub quit {
  my %incoming = ();
  (
    $incoming{'message'},
    $incoming{'errorLevel'}
  ) = @_;
  $incoming{'errorLevel'} = 0 if (!defined($incoming{'errorLevel'}));
  
  
  ## Print exit message
  if ($incoming{'message'}) { 
    printmsg($incoming{'message'}, 0);
  }
  
  ## Exit
  exit($incoming{'errorLevel'});
}