getbookmark.pl

#!/usr/bin/perl

use strict;

# Syntax: perl getbookmark.pl onetimepad_file

# This displays the value of the book marked from the given one-time pad. 

# Execution starts here
&main;

sub main()
{
	my $intNumArgs = $#ARGV + 1;
	if ($intNumArgs != 1)
	{
		print "Syntax: perl getbookmark.pl onetimepad_file\n";
		exit 1;
	}
	
	# Read the arguments on the command line
	my $strPadFilename = $ARGV[0];

	my $lngBookmark = ReadBookmark($strPadFilename);
	if ($lngBookmark == 0)
	{
		exit 1;
	}
	print "Bookmark is ".$lngBookmark."\n";
	exit 0;
}

sub ReadBookmark($)
{
	my $strPadFilename = $_[0];

	if (!open PAD_FILE, "<$strPadFilename")
	{
		print "ERROR:Can't open file $strPadFilename\n";
		return 0;
	}
	# Handle the file as bytes instead of text
	binmode PAD_FILE;

	my $lngBookmark = unpack('L', <PAD_FILE>);
	close PAD_FILE;

	return $lngBookmark;
}

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