NAME
	  sigvec - Provides a compatibility interface to the sigac-
	  tion() function

     SYNOPSIS
	  #include <sys/signal.h>
	  int sigvec (
	       int signal,
	       struct sigvec *in_vec,
	       struct sigvec *out_vec );

     PARAMETERS
	  signal
	       Specifies the signal number.

	  in_vec
	       Points to a sigvec() structure that specifies the
	       action to be taken when the specified signal is
	       delivered, the mask to be used when calling the signal
	       handler,	and the	flags that modify signal behavior.

	  out_vec
	       Points to a sigvec() structure that is set to the pre-
	       vious signal action state on successful return from the
	       sigvec()	function.

     DESCRIPTION
	  The sigvec() function	is provided for	compatibility to old
	  UNIX systems;	 its function is a subset of that available
	  with the sigaction() function. Like the sigaction() func-
	  tion,	the sigvec() function allows the user to set the
	  action to take upon the receipt of a signal and to specify a
	  signal handler mask to block signals before calling the sig-
	  nal handler. However,	only signals with values 1 to 31 can
	  be masked on entry to	a signal-handler set up	with the
	  sigvec() function.

	  The sigvec() structure has the following members:

	    void (*sv_handler)(	);
	    int	 sv_mask;
	    int	 sv_flags;

	  The sv_handler field specifies the action for	the signal,
	  and can be SIG_DFL, SIG_IGN, or the address of a signal
	  handler function. See	the sigaction()	function for a
	  detailed description of the signal actions.

	  The sv_mask field specifies a	mask which specifies signals
	  to block (in addition	to any signals already blocked at time
	  of delivery) when the	signal handler function	is called for
	  the signal. Signal i is blocked if the i-th bit of the mask
	  is set. Only signals with values 1 to	31 can be masked with
	  the sigvec() function.  The sv_flags field contains flags
	  that further specify signal behavior.	 If SV_ONSTACK is set,
	  the signal handler runs on the signal	stack specified	by the
	  sigstack() function;	otherwise, the signal handler runs on
	  the stack of the process receiving the signal.  If
	  SV_INTERRUPT is set, a system	call that is interrupted by
	  signal returns a value of -1 with errno set to [EINTR];
	  otherwise, a system call interrupted by signal is restarted.

	  If the value of the in_vec parameter is a null pointer, then
	  the signal handler information is not	set. If	the value of
	  the out_vec parameter	is null, then the previous signal
	  handler information is not returned.

	  Once a signal	handler	is assigned, it	remains	assigned until
	  another call to the sigvec(),	signal(), sigaction(), or exec
	  function is made.

     NOTES
	  The sigvec() function	is provided for	compatibility only,
	  and its use is not recommended.   Programs should use	the
	  sigaction() function instead.

	  The sigvec() function	does not check the validity of the
	  sv_handler field pointer. If it points to a location outside
	  of the process address space,	the process receives a memory
	  fault	when the system	attempts to call the signal handler.
	  If the sv_handler field points to anything other than	a
	  function, the	results	are unpredictable.

	  The signal-handler function can be declared as follows:

	  void handler (
	       int signal );

     RETURN VALUES
	  Upon successful completion, a	value of 0 (zero) is returned.
	  If the sigvec() function fails, a value of -1	is returned
	  and errno is set to indicate the error.

     ERRORS
	  If the sigvec() function fails, no new signal	handler	is
	  installed and	errno may be set to one	of the following
	  values:

	  [EFAULT]  The	in_vec or out_vec parameter points to a	loca-
		    tion outside of the	process' address space.

	  [EINVAL]  The	signal parameter is not	a valid	signal number.

	  [EINVAL]  An attempt was made	to ignore or supply a handler
		    for	the SIGKILL signal.

     RELATED INFORMATION
	  Functions: kill(2), ptrace(2), sigaction(2), sigblock(2),
	  sigpause(3), sigstack(2)