typedef void (*sighandler_t) (int);

sighandler_t signal (int signum, sighandler_t handler);

struct sigaction
{
  void (*sa_handler) (int);
  void (*sa_sigaction) (int, siginfo_t *, void *);
  sigset_t sa_mask;
  int sa_flags;
}

struct siginfo_t
{
  int      si_signo;    // Signal number
  int      si_errno;    // Value of errno
  int      si_code;     // Additional signal code
  pid_t    si_pid;      // Sending process PID
  uid_t    si_uid;      // Sending process UID
  int      si_status;   // Exit value
  clock_t  si_utime;    // User time consumed
  clock_t  si_stime;    // System time consumed
  sigval_t si_value;    // Signal value
  int      si_int;      // Integer value sent with signal
  void *   si_ptr;      // Pointer value sent with signal
  void *   si_addr;     // Associated memory address
  int      si_fd;       // Associated file descriptor
}

int sigaction (int signum, const struct sigaction *act, struct sigaction *oldact);