Upload & Process uploaded file drupal

function test_import($form, &$form_state) {
  $form['csv_file'] = array(
      '#title'          => t('Upload a csv file'),
      '#type'         => 'file',
      '#description'  => t('Must be smaller than 5MB in size.'),
     );
  $form[] = array(
      '#type'  => 'submit',
      '#value'  => 'Process',
    );

  return $form;
}

function test_import_validate($form, &$form_state) {
  $validators = array(
     'file_validate_extensions' => array( 'csv' ),
     'file_validate_size' => array(variable_get('btn_file_size', '5') * 1024),
  );
  // the others validators are http://api.drupal.org/api/drupal/includes!file.inc/group/file/7

  $destination = FALSE;
  // $destination = 'public://testimport/';

  $fileObj = file_save_upload('csv_file', $validators, $destination);
  if (!$fileObj) {
    form_set_error('csv_file', t('Oh Unable to access file or file is missing.'));
  }

}

function test_import_submit($form, &$form_state) {

  $fileObj = file_save_upload( 'csv_file');
  if (!$fileObj) {
    form_set_error('csv_file', t('Unable to access file or file is missing.'));
  }

  ini_set('auto_detect_line_endings', true);
  $file = fopen( drupal_realpath($fileObj->uri), 'r');

  while(!feof($file)) {
    $line = fgets($file);
    $data = explode("\t", $line);
    dpm($data[0]);
  }

  fclose($file);

}


related :
http://api.drupal.org/api/drupal/developer%21topics%21forms_api_reference.html/7#managed_file
http://api.drupal.org/api/examples/image_example%21image_example.pages.inc/7