Tribblix: manual page: stack

STACK_VIOLATION(3C) Standard C Library Functions STACK_VIOLATION(3C)

NAME

stack_violation - determine stack boundary violation event

SYNOPSIS

#include <ucontext.h>

int stack_violation(int sig, const siginfo_t *sip,
const ucontext_t *ucp);

DESCRIPTION

The stack_violation() function returns a boolean value indicating
whether the signal, sig, and accompanying signal information, sip,
and saved context, ucp, represent a stack boundary violation event or
a stack overflow.

RETURN VALUES

The stack_violation() function returns 0 if the signal does not
represent a stack boundary violation event and 1 if the signal does
represent a stack boundary violation event.

ERRORS

No errors are defined.

EXAMPLES

Example 1: Set up a signal handler to run on an alternate stack.

The following example sets up a signal handler for SIGSEGV to run on
an alternate signal stack. For each signal it handles, the handler
emits a message to indicate if the signal was produced due to a stack
boundary violation.

#include <stdlib.h>
#include <unistd.h>
#include <ucontext.h>
#include <signal.h>

static void
handler(int sig, siginfo_t *sip, void *p)
{
ucontext_t *ucp = p;
const char *str;

if (stack_violation(sig, sip, ucp))
str = "stack violation.\n";
else
str = "no stack violation.\n";

(void) write(STDERR_FILENO, str, strlen(str));

exit(1);
}

int
main(int argc, char **argv)
{
struct sigaction sa;
stack_t altstack;

altstack.ss_size = SIGSTKSZ;
altstack.ss_sp = malloc(SIGSTKSZ);
altstack.ss_flags = 0;

(void) sigaltstack(&altstack, NULL);

sa.sa_sigaction = handler;
(void) sigfillset(&sa.sa_mask);
sa.sa_flags = SA_ONSTACK | SA_SIGINFO;
(void) sigaction(SIGSEGV, &sa, NULL);

/*
* The application is now set up to use stack_violation(3C).
*/

return (0);
}

USAGE

An application typically uses stack_violation() in a signal handler
that has been installed for SIGSEGV using sigaction(2) with the
SA_SIGINFO flag set and is configured to run on an alternate signal
stack.

ATTRIBUTES