#include<stdio.h>
    #include<stdlib.h>
    
    
    /**
      *
      * This binary receives 2 numbers, an L and an R
      *
      * It will intentionally hit Segmentation Fault(actually SIGSEGV) whenever 30 is in the interval [L,R]
      *
      * It will be used to test the binary search segfault finder
      *
      */
    int main(int argc, int **argv) {
      char exists;
      char *Q[3000];
      int i;
      int L = atoi((char*)argv[1]);
      int R = atoi((char*)argv[2]);
    
      printf("L=%d R=%d",L,R);
      /*exit(0);*/
      for(i=0;i<3000;i++)
        Q[i] = &exists;
    
      Q[30] = NULL; // <==== I want to cause a SIGSEGV through this !
    
      for(i=L;i<=R;i++) {
        int T = *Q[i]; // <== will segfault when i == 30 because I said so :)
      };
    };

##</code><code>##

    #!/usr/bin/env perl
    use strict;
    use warnings;
    

    
    my $segfaulting_file = "s";
    my $L = 0;
    my $R = 7266786; #`cat $segfaulting_file | wc -l`;
    my $M;
    my $binary = "./filter";
    
    while ($L < $R) {
      $M     = int(($L+$R)/2);
      # head argument for right side
      my $HL = $M;
      # tail argument for right side
      my $TL = $M-$L;
      # head argument for left  side
      my $HR = $R;
      # tail argument for left  side
      my $TR = $R-$M;
    
      print "M=$M L=$L R=$R\n";
      my $go_left ;
      my $go_right;
      my $cmd_R = "cat $segfaulting_file | head -$HR | tail -$TR | $binary > /dev/null;";
      my $cmd_L = "cat $segfaulting_file | head -$HL | tail -$TL | $binary > /dev/null;";
    
      print "\nRunning $cmd_R\n";
      `$cmd_R`;
      #`./a.out $M $R`;
      print "RETVAL=$?\n";
      $go_right = ($? > 30000); # right side caused SEGFAULT
      `rm core`;
      print "\nRunning $cmd_L\n";
      `$cmd_L`;
      print "RETVAL=$?\n";
      #`./a.out $L $M`;
      $go_left  = ($? > 30000); # left  side caused SEGFAULT
      `rm core`;
    
      if(  $L == $R ) {
        last;
      }elsif ( $go_left  ) {
        print "GO left  L=$L R=$R\n";
        $R = $M  ;
      }elsif ( $go_right ) {
        print "GO right L=$L R=$R\n";
        $L = $M+1;
      };
    };
    
    
    # the loop stopped because $L==$R==$M , so we just print out $M
    print "Segfault caused by line $M\n";