How to Ensure Reliable Large File Downloads in PHP?

Reliable Large File Downloads in PHP

In PHP, transferring large files seamlessly poses a challenge. To ensure file integrity during downloads, exploring alternatives to the classic file-read (fread) approach is crucial.

Options for Improved File Transfers

Consider utilizing functions like http_send_file and http_send_data. These functions handle file transmission more efficiently, potentially resolving the issues associated with using fread.

Chunking Files

If more professional options are unavailable, chunking files is a practical solution. By dividing the file into smaller segments, PHP can transmit them incrementally, reducing the risk of errors. The following code demonstrates how to implement this technique:

$chunksize = 5 * (1024 * 1024); // 5 MB per chunk

if (file_exists($filename)) {
  header('Content-Length: ' . filesize($filename));

  if (filesize($filename) > $chunksize) {
    $handle = fopen($filename, 'rb');

    while (!feof($handle)) {
      print(@fread($handle, $chunksize));

      ob_flush();
      flush();
    }

    fclose($handle);
  } else {
    readfile($path);
  }

  exit;
} else {
  echo 'File "' . $filename . '" does not exist!';
}

Remember to ensure your file is saved in UTF-8 encoding to avoid corruption during the download process.

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