.\" Copyright (c) 1983 Regents of the University of California.
.\" All rights reserved. The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\" @(#)sigstack.2 6.2 (Berkeley) %G%
sigstack \- set and/or get signal stack context
.B struct sigstack *ss, *oss;
allows users to define an alternate stack on which signals
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
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.
is non-zero, the current signal stack state is returned.
Signal stacks are not ``grown'' automatically, as is
done for the normal stack. If the stack overflows
unpredictable results may occur.
Upon successful completion, a value of 0 is returned.
Otherwise, a value of \-1 is returned and
is set to indicate the error.
will fail and the signal stack context will remain unchanged
if one of the following occurs.
points to memory that is not a valid part of the process