How to Reliably Download Large Files in PHP: What Techniques Can Avoid Corrupted or Incomplete Transfers?

Downloading Large Files Reliably in PHP: Addressing Transfer Issues

When downloading large files through PHP, encountering problems with corrupted or incomplete transfers can be frustrating. To tackle this issue, consider the following approaches:

Chunking Files

The simplest method in PHP is to chunk the files into smaller segments. This technique is particularly effective for large files that exceed PHP's memory limits.

$filename = $filePath . $filename;
$chunksize = 5 * (1024 * 1024);

if (file_exists($filename)) {
    set_time_limit(300);
    $size = filesize($filename);

    // Set headers
    header('Content-Type: application/octet-stream');
    header('Content-Transfer-Encoding: binary');
    header('Content-Length: ' . $size);

    if ($size > $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!';
}

Alternative Functions

Apart from fopen and fgets, consider using PHP functions like http_send_file or http_send_data. These functions are specifically designed for sending file contents and may improve transfer reliability.

Dedicated Scripts

For more advanced scenarios, explore dedicated scripts that leverage protocols like cURL or FTP to handle file downloads efficiently. These scripts can provide additional control and flexibility.

Additional Considerations

Ensure your file is saved in UTF-8 encoding to prevent corruption during download. Verify that your server has sufficient memory and time limits to handle large downloads. If necessary, increase the memory limit using ini_set('memory_limit', '1G').

The above is the detailed content of How to Reliably Download Large Files in PHP: What Techniques Can Avoid Corrupted or Incomplete Transfers?. For more information, please follow other related articles on the PHP Chinese website!