#!/usr/bin/perl

use File::Copy;


$ext_options = "noatime";
$swap_options = "noatime";
$vfat_options = "noatime,umask=0";
$reiserfs_options = "notail,noatime";

$tmpfs = "none /tmp tmpfs size=256m,nosuid,nodev,noatime 0 0\n";



sub removeParameter {
$line = $_[0];
$todel = $_[1];

$pos = rindex($line, $todel);
if ( $pos < 0 ) { return $line; }

$start = substr($line, 0, $pos);
$end = substr($line, $pos + length($todel), length($line));


$notready = "0";
$pos2 = 0;

while ( $notready le "1" ) {
        $ichar = substr($end, $pos2, 1);
        if ( $ichar ne "," && $ichar ne "=" && $ichar !~ /[0-9]/ ) {last}
        $pos2++;
}


$end = substr($end, $pos2, length($end));
$start_last_char = substr($start, length($start)-1, 1);
$end_first_char = substr($end, 0, 1);
if ( $start_last_char eq "," && $end_first_char !~ /[a-z]/ ) { $start = substr($start, 0, length($start)-1); }

$final = $start.$end;

return $final;
}



# --------------------------------------------------------------------------------------
# Main script:
# --------------------------------------------------------------------------------------

copy("/etc/fstab", "/etc/_fstab") or die "Cannot backup /etc/fstab, stopping!\n\n";

$newfile = "";

open (FILE, '/etc/fstab');
	$wholefile = <FILE>;
	if ( rindex($wholefile, "/tmp") > 0 ) { print "/etc/fstab already modified, exiting...\n"; exit 0; }
	
	while (<FILE>) {
	chomp;
	$line = $_;
	$line = removeParameter($line, "relatime");
	$line = removeParameter($line, "umask");
	$line = removeParameter($line, "gid");
	$linelen = length($line);
	$position = -1;

	if ( $position < 0 ) {
		$position = rindex($line, "ext");
		if ( $position > 0 ) { $newoptions = $ext_options; $position = $position + 5; }
	}

	if ( $position < 0 ) {
		$position = rindex($line, "swap");
		if ( $position > 0 ) { $newoptions = $swap_options; $position = $position + 5; }
	}

	if ( $position < 0 ) {
		$position = rindex($line, "vfat");
		if ( $position > 0 ) { $newoptions = $vfat_options; $position = $position + 5; }
	}

	if ( $position < 0 ) {
		$position = rindex($line, "reiserfs");
		if ( $position > 0 ) { $newoptions = $reiserfs_options; $position = $position + 9; }
	}

	$commentpos = rindex($line, "\#");
	if ( $position > 0 ) {
	if ( $commentpos < 0 || $commentpos > $position ) {

	for ($pos = $position; $pos < $linelen; $pos++) {
		if ( rindex($line, $newoptions) > 0 ) {last}
		$char = substr($line, $pos, 1);
		if ( $char eq "\#" ) {last}

		$rest = substr($line, $pos, length($line));
		if ( $char =~ /[a-z]/ ) {
			substr($line, $pos, $pos, $newoptions.",".$rest);
			{last}
		}
	}
	}
	}
	
	$newfile = "$newfile$line\n";
}

close (FILE); 

if ( rindex($newfile, "/tmp") < 0 ) { $newfile = $newfile.$tmpfs; }


open( FILE, ">/etc/fstab" );
print FILE $newfile;
close(FILE);



system "cat /etc/fstab";