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  repre-
       sent 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.
";
		 else
			 str = "no stack violation.
";

		 (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_SIG-
       INFO flag set and is configured to run on an alternate signal stack.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Evolving			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Async-Signal-Safe 	   |
       +-----------------------------+-----------------------------+

SEE ALSO

       sigaction(2), sigaltstack(2), stack_getbounds(3C), stack_inbounds(3C), stack_setbounds(3C), attributes(5)

SunOS 5.11							    18 Jul 2002 					       stack_violation(3C)