extern int sys_nerr;
extern char *sys_errlist[];

/* strerror
 *
 * Return string corresponding to errno
 * For systems which lack this function.
 */
const char *
strerror(int errnum)
{
  static char unknown[] = "Unknown error";

  return ((unsigned int)errnum < sys_nerr) ? sys_errlist[errnum] : unknown;
}