SIGSTACK(2)	    UNIX Programmer's Manual	      SIGSTACK(2)



NAME
     sigstack - set and/or get signal stack context

SYNOPSIS
     #include <signal.h>

     struct sigstack {
	caddr_t     ss_sp;
	int    ss_onstack;
     };

     sigstack(ss, oss);
     struct sigstack *ss, *oss;

DESCRIPTION
     This interface has been made obsolete sigaltstack(2).

     _S_i_g_s_t_a_c_k allows users to define an alternate stack on which
     signals are to be processed.  If _s_s is non-zero, it speci-
     fies a _s_i_g_n_a_l _s_t_a_c_k on which to deliver signals and tells
     the system if the process is currently executing on that
     stack.  When a signal's action indicates its handler should
     execute on the signal stack (specified with a _s_i_g_v_e_c(2)
     call), the system checks to see if the process is currently
     executing on that stack.  If the process is not currently
     executing on the signal stack, the system arranges a switch
     to the signal stack for the duration of the signal handler's
     execution. If _o_s_s is non-zero, the current signal stack
     state is returned.

NOTES
     Signal stacks are not ``grown'' automatically, as is done
     for the normal stack.  If the stack overflows unpredictable
     results may occur.

RETURN VALUE
     Upon successful completion, a value of 0 is returned.  Oth-
     erwise, a value of -1 is returned and _e_r_r_n_o is set to indi-
     cate the error.

ERRORS
     _S_i_g_s_t_a_c_k will fail and the signal stack context will remain
     unchanged if one of the following occurs.

     [EFAULT]	    Either _s_s or _o_s_s points to memory that is not
		    a valid part of the process address space.

SEE ALSO
     sigvec(2), setjmp(3)

HISTORY
     The sigstack function call appeared in 4.2BSD and has been



Printed 11/26/99	September 3, 1997			1






SIGSTACK(2)	    UNIX Programmer's Manual	      SIGSTACK(2)



     deprecated.






















































Printed 11/26/99	September 3, 1997			2