#include <signal.h>
#include <errno.h>
int
sigaction(int _sig, const struct sigaction *_act, struct sigaction *_oact)
{
int retval = 0;
if (_oact)
{
void (*installed_sig)(int) = signal (_sig, SIG_IGN);
if (installed_sig == SIG_ERR)
{
retval = -1;
errno = EINVAL;
}
else
signal (_sig, installed_sig);
_oact->sa_handler = installed_sig;
retval = sigemptyset (&_oact->sa_mask);
_oact->sa_flags = 0;
}
if (_act)
{
if (signal (_sig, _act->sa_handler) == SIG_ERR)
{
retval = -1;
errno = EINVAL;
}
}
return 0;
}