sigstack - Sets and gets signal stack context
int sigstack (
struct sigstack *instack,
struct sigstack *outstack );
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instack Points to the structure describing the new signal stack.
outstack Points to the structure where the current signal stack state is
The sigstack() function defines an alternate stack on which signals are to
If the value of the instack parameter is nonzero, it points to a sigstack()
structure, which has the following members:
int ss_onstack; }
The value of instack->ss_sp specifies the stack pointer of the new signal
stack. The value of instack->ss_onstack should be set to 1 if the process
is currently running on that stack; otherwise, it should be 0 (zero).
If the value of the instack parameter is 0 (that is, a null pointer), the
signal stack state is not set.
If the value of the outstack parameter is nonzero, it points to a sig-
stack() structure into which the sigstack() function stores the current
signal stack state. If the value of the outstack parameter is 0 (zero),
the previous signal stack state is not reported.
When a signal occurs and its handler is to run on the signal stack, the
system checks to see if the process is already running on that stack. If
so, the process continues to run on that stack even after the handler
returns. If not, the signal handler runs on the signal stack, and the ori-
ginal stack is restored when the handler returns.
Use the sigaction() function to specify whether a given signal handler rou-
tine is to run on the signal stack.
A signal stack does not automatically increase in size as a normal stack
does. If the stack overflows, unpredictable results can occur.
The sigstack() function is scheduled to be withdrawn from a future version
of the X/Open CAE Specification. When writing or rewriting portable appli-
cations, use the sigaltstack() function instead of sigstack().
Upon successful completion, a value of 0 (zero) is returned. Otherwise, a
value of -1 is returned and errno is set to indicate the error.
The sigstack() function sets errno to the specified values for the follow-
[EFAULT] The instack or outstack parameter points outside of the address
space of the process.
Functions: setjmp(3), sigaction(2), sigvec(2)