/* SYSVR4 and ANSI compatible signal(2). */

#include <lib.h>

#define sigaction _sigaction

#define sigemptyset _sigemptyset

#include <signal.h>

PUBLIC sighandler_t signal(sig, disp)

int sig; /* signal number */

sighandler_t disp; /* signal handler, or SIG_DFL, or SIG_IGN */

{

struct sigaction sa, osa;

if (sig <= 0 || sig > _NSIG || sig == SIGKILL) {

errno = EINVAL;

return(SIG_ERR);

}

sigemptyset(&sa.sa_mask);

#ifdef WANT_UNRELIABLE_SIGNALS

/* Allow the signal being handled to interrupt the signal handler. */

sa.sa_flags = SA_NODEFER;

/* When signal is caught, reset signal handler to SIG_DFL for all but

* SIGILL and SIGTRAP.

*/

if (sig != SIGILL && sig != SIGTRAP) sa.sa_flags |= SA_RESETHAND;

#else

sa.sa_flags = 0;

#endif

sa.sa_handler = disp;

if (sigaction(sig, &sa, &osa) < 0) return(SIG_ERR);

return(osa.sa_handler);

}