In tài liệu bằng php

Send file with HTTPRange support [partial download]:

function smartReadFile[$location, $filename, $mimeType='application/octet-stream']
{ if[!file_exists[$location]]
  { header ["HTTP/1.0 404 Not Found"];
    return;
  }

  $size=filesize[$location];
  $time=date['r',filemtime[$location]];

  $fm=@fopen[$location,'rb'];
  if[!$fm]
  { header ["HTTP/1.0 505 Internal server error"];
    return;
  }

  $begin=0;
  $end=$size;

  if[isset[$_SERVER['HTTP_RANGE']]]
  { if[preg_match['/bytes=\h*[\d+]-[\d*][\D.*]?/i', $_SERVER['HTTP_RANGE'], $matches]]
    { $begin=intval[$matches[0]];
      if[!empty[$matches[1]]]
        $end=intval[$matches[1]];
    }
  }

  if[$begin>0||$end