Cannot read large files

[shinout]

The code below doen't work correctly.

const fs = require('fs');
var fd = fs.openSync('largefile.txt', 'r'); // largefile.txt is a very large file.
var data = fs.readSync(fd, 100, 5294756210);

Then, the variable 'data' contains data from the beginning of the file.
A similar situation also happens in using fs.createReadStream().

I've also checked the largest start position we can put,
using code like below.

var start = 529475621;  // working correctly
var limit = 5294756210; // not working correctly
var count = 0;
while (count < 100000) {
  var data = fs.readSync(fd, 100, r);
  var invalid = (data[0].substr(0,10) == 'start chars');
  if (invalid) {
    r -= Math.floor((r - start)/2);
  }
  else {
    r += Math.floor((limit - r)/2);
  }
  count++;
  console.log(count, r, data[0].substr(0,10));
}   

then I found that if the variable [r] is the same value,
the variable [data] could change with time.