sigstack(2)sigstack(2)NAMEsigstack - Set and get the signal stack context
SYNOPSIS
#include <signal.h>
int sigstack(
struct sigstack *instack,
struct sigstack *outstack );
STANDARDS
Interfaces documented on this reference page conform to industry stan‐
dards as follows:
sigstack(): XSH4.0, XSH4.2, XSH5.0
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
PARAMETERS
Points to the structure describing the new signal stack. Points to the
structure where the current signal stack state is stored.
DESCRIPTION
The sigstack() function defines an alternate stack on which signals are
to be processed.
If the value of the instack parameter is nonzero, it points to a
sigstack structure, which has the following members:
struct sigstack{
caddr_t ss_sp;
int ss_onstack; }
The value of instack->ss_sp specifies the stack pointer of the new sig‐
nal 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
sigstack structure into which the sigstack() function stores the cur‐
rent 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 han‐
dler returns. If not, the signal handler runs on the signal stack, and
the original stack is restored when the handler returns.
Use the sigaction() function to specify whether a given signal handler
routine is to run on the signal stack.
NOTES
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 defined as a LEGACY function by the XSH
specification. XSH recommends that sigaltstack() rather than sigstack()
be used when creating or rewriting portable applications.
RETURN VALUES
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.
ERRORS
The sigstack() function sets errno to the specified value for the fol‐
lowing conditions: [Tru64 UNIX] The instack or outstack parameter
points outside of the address space of the process. An attempt was
made to modify an active stack.
SEE ALSO
Functions: sigaction(2), sigvec(2), setjmp(3)
Standards: standards(5)sigstack(2)
