#include <syscall.h>
#include <signal.h>
#include <stdio.h>
#include <ucontext.h>

int is_blocked(int sig)
{
    sigset_t set;
    sigprocmask(SIG_BLOCK, NULL, &set);
    return sigismember(&set, sig);
}

void *eip(struct ucontext *context)
{
    return (void *)context->uc_mcontext.gregs[14];
}

void sig_1(int sig, siginfo_t *info, struct ucontext *context)
{
    printf("%d %d\n", sig, is_blocked(2));
    printf("eip: %x\n", eip(context));
}

void sig_2(int sig, siginfo_t *info, struct ucontext *context)
{
    printf("%d %d\n", sig, is_blocked(1));
    printf("eip: %x\n", eip(context));
}

int tkill(int tid, int sig)
{
    syscall(SYS_tkill, tid, sig);
}

int main(void)
{
    sigset_t set;

    struct sigaction sa;
    sa.sa_flags = SA_SIGINFO;
    sigemptyset(&sa.sa_mask);
    sa.sa_sigaction = sig_1;
    sigaction(1, &sa, 0);
    sa.sa_sigaction = sig_2;
    sigaction(2, &sa, 0);

    sigemptyset(&set);
    sigaddset(&set, 1);
    sigaddset(&set, 2);
    printf("sig_1=%x\n", sig_1);
    printf("sig_2=%x\n", sig_2);
    sigprocmask(SIG_BLOCK, &set, NULL);

    kill(getpid(), 1);
    kill(getpid(), 2);

    sigprocmask(SIG_UNBLOCK, &set, NULL);

    return 0;
}