Download helper to download files in chunks and save it

fileDownload.php

<?php
/**
 * @file
 * Download helper to download files in chunks and save it.
 *
 * @author Syed I.R
 * @author Modified by: Nick Mathew
 * @link https://github.com/irazasyed
 */

/**
 * Download files in chunks and save it.
 *
 * @param string $srcName
 *   Source Path/URL to the file you want to download.
 * @param string $dstName
 *   Destination Path to save your file.
 * @param int $chunkSize
 *   (Optional) How many bytes to download per chunk (In MB). Defaults to 1 MB.
 * @param bool $returnbytes
 *   (Optional) Return number of bytes saved. Default is TRUE.
 *
 * @return int
 *   Returns number of bytes delivered.
 */
function download_file($srcName, $dstName, $chunkSize = 1, $returnbytes = TRUE) {
  // How many bytes per chunk.
  $chunksize = $chunkSize * (1024 * 1024);
  $data = '';
  $bytesCount = 0;
  $handle = fopen($srcName, 'rb');
  $fp = fopen($dstName, 'w');
  if ($handle === FALSE) {
    return FALSE;
  }
  while (!feof($handle)) {
    $data = fread($handle, $chunksize);
    fwrite($fp, $data, strlen($data));
    if ($returnbytes) {
      $bytesCount += strlen($data);
    }
  }
  $status = fclose($handle);
  fclose($fp);
  if ($returnbytes && $status) {
    // Return number of bytes delivered like readfile() does.
    return $bytesCount;
  }
  return $status;
}