More on File Upload Handle In PHP

Some problem with PHP file upload handle:
Make sure the file size not exceed desired value
allow certain fype type: to prevent user upload harmful content.
In my current project. I have to solve it all. In this artice, I will share you some of the trick. If you like to know more, feel free to ask question by commenting.

Make a Upload function:

////////////////////
function upload_file($user_file,
                     $dest_dir,
                     $max_file_size,
                     $to_file_name='')
{

    $file_name=(empty($to_file_name))
               ? $_FILES[$user_file]['name']
               : $to_file_name;
    $file_size=$_FILES[$user_file]['size'];
    $temp_file=$_FILES[$user_file]['tmp_name'];
    $upload_file="$dest_dir/$file_name";
    $err='';
    if ($_FILES[$user_file]['error'])
    {
       $err=upload_error_message(
             $_FILES[$user_file]['error']
             );
       message_warning($err);
       return false;
    }
    echo "
Uploading file $file_name...";
    if (DEBUG)
    {
       echo  "to $upload_file";
    }
    if (is_uploaded_file($temp_file))
    { //check size
       if ($file_size>$max_file_size)
       {
          message_warning("
          File size too large: $file_size
          ");
          unlink($temp_file);
          return false;
       }
       if (file_exists($upload_file))
       {
          message_warning('File Existed');
          unlink($temp_file);
          return false;
       }
       if (move_uploaded_file($temp_file,$upload_file))
       {
          echo "
File uploaded: $file_name!";
          return true;
       }
       else
       {
          message_warning('Cannot copy file!');
          return false;
       }
    }
    else
    {
        message_warning('Upload Failed!');
        return false;
    }
}

Upload form valiate:

function validate_upload_form($update=false)
{
   global $file_name;
   global $tempfile;
   global $err_file;

   $ok=true;
   if (empty($file_name))
   {
      $err_songfile='
       No file specified!';
      $ok=false;
   }
   else
   {
       $ext=get_ext($file_name);
       if (!is_ext_allowed($ext))
       {
           $err_file='
           Exentions not allow';
           $ok=false;
       }

   }

   if ( (!$ok)&&(!empty($tempfile)) )
   {
       delete_file($tempfile);
   }
   return $ok;
}

Get File extension:

function get_ext($filename)
{
    if (!empty($filename))
    {
       $pathinfo=pathinfo($filename);
       return $pathinfo['extension'];
    }
    else
    {
       return 'Unkown';
    }
}

Is an extension allow?

//
define ("EXT_ALLOWED",'mp3,wma,rm,mov,mid,swf,wmv');
function is_ext_allowed($ext)
{
   $EXT_ALLOWED=explode(',',EXT_ALLOWED);
   return in_array(strtolower($ext),$EXT_ALLOWED);
}

Upload error message:

function upload_error_message($err_code)
{
   switch ($err_code)
   {
      case UPLOAD_ERR_OK:
         return 'No error';
      case UPLOAD_ERR_INI_SIZE:
         $max_size=return_bytes(
                   ini_get('upload_max_filesize')
                   );
         return 'The uploaded file exceeds
                 the upload_max_filesize directive
                 in php.ini: '.$max_size.' bytes';
      case UPLOAD_ERR_FORM_SIZE:
         return 'The uploaded file exceeds
                 the MAX_FILE_SIZE directive that
                 was specified in the HTML form.';
      case UPLOAD_ERR_PARTIAL:
         return 'The uploaded file
                 was only partially uploaded';
      case UPLOAD_ERR_NO_FILE:
         return 'No file was uploaded';
      case UPLOAD_ERR_NO_TMP_DIR:
         return 'Missing a temporary folder';
      case UPLOAD_ERR_CANT_WRITE:
         return 'Failed to write file to disk';
      default:
         return 'Unkown error';
   }
}

Upload Processing...

   switch ($_action)
   {
      case 'upload':
         if(validate_upload_form())
         {
            upload_processing();
         }
         else
         {
            show_upload_form();
         }
         break;
      default:
         show_upload_form();
         break;