SIGSTACK(2)                                                        SIGSTACK(2)



NAME
     sigstack - set and/or get signal stack context

SYNOPSIS
     #include <signal.h>

     struct sigstack {
          caddrt   sssp;
          int  ssonstack;
     };

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

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

     1) #define
        BSDSIGNALS
        or
        BSDCOMPAT
        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
     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
     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.  Otherwise, a value
     of -1 is returned and errno is set to indicate the error.






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SIGSTACK(2)                                                        SIGSTACK(2)



ERRORS
     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
     sigvec(3b), setjmp(3)














































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