use strict;

&foo;
&badfoo;

sub foo {
	&bar;
}

sub badfoo {
	&bar;
}

sub bar {
	if ((caller(1))[3] ne 'main::foo') {
		die((caller(0))[3], 
			": can not be called from ", 
			(caller(1))[3], 
			" due to restrictions");
	}
	print "called sub ",(caller(0))[3], "\n";
}