incomplete_line (void)
{
  FILE *fp = pfp;
  int c;
  file_offset line_beginning = file_tell (fp);

  if (getc (fp) == '\\')
    {
      while ((c = getc (fp)) != '\n'  &&  c != EOF)
	/* do nothing */ ;
      return true;
    }
  else
    {
      /* We don't trust ungetc.  */
      Fseek (pfp, line_beginning, SEEK_SET);
      return false;
    }
}

The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.