SIGSTACK(2)							   SIGSTACK(2)

NAME    [Toc]    [Back]

     sigstack -	set and/or get signal stack context

SYNOPSIS    [Toc]    [Back]

     #include <signal.h>

     struct sigstack {
	  caddr_t   ss_sp;
	  int  ss_onstack;
     };

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

     Sigstack
     is	used in	conjunction with sigvec(3b) which requires you to either

     1)	#define
	_BSD_SIGNALS
	or
	_BSD_COMPAT
	before including <signal.h>,
	or

     2)	specify	one of them in the compile
	command	or makefile:

	  cc -D_BSD_SIGNALS -o prog prog.c

DESCRIPTION    [Toc]    [Back]

     Sigstack allows users to define an	alternate stack	on which signals are
     to	be processed.  If ss is	non-zero, it specifies a signal	stack 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 sigvec(3b) 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 oss	is non-zero, the current signal	stack
     state is returned.

NOTES    [Toc]    [Back]

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

RETURN VALUE    [Toc]    [Back]

     Upon successful completion, a value of 0 is returned.  Otherwise, a value
     of	-1 is returned and errno is set	to indicate the	error.






									Page 1






SIGSTACK(2)							   SIGSTACK(2)

ERRORS    [Toc]    [Back]

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

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

SEE ALSO    [Toc]    [Back]

     sigvec(3b), setjmp(3)


									PPPPaaaaggggeeee 2222