#include <bits/errno-return.h>
#include <signal.h>
#include <sys/syscall.h>
#include <unistd.h>

extern "C" void sigreturn();

extern "C"
{
    int sigaction(int signo, const struct sigaction* act, struct sigaction* oldact)
    {
        long rc = syscall(SYS_sigaction, signo, act, oldact, sigreturn);
        __errno_return(rc, int);
    }

    __simple_sighandler_t signal(int signo, __simple_sighandler_t handler)
    {
        struct sigaction act, oldact;
        act.sa_handler = handler;
        sigemptyset(&act.sa_mask);
        act.sa_flags = 0;

        if (sigaction(signo, &act, &oldact) < 0) return SIG_ERR;

        return oldact.sa_handler;
    }

    int kill(pid_t pid, int signo)
    {
        long rc = syscall(SYS_kill, pid, signo);
        __errno_return(rc, int);
    }

    int raise(int signo)
    {
        return kill(getpid(), signo);
    }

    int sigprocmask(int how, const sigset_t* set, sigset_t* oldset)
    {
        long rc = syscall(SYS_sigprocmask, how, set, oldset);
        __errno_return(rc, int);
    }

    int sigemptyset(sigset_t* set)
    {
        *set = 0;
        return 0;
    }

    int sigfillset(sigset_t* set)
    {
        *set = 0xffffffff;
        return 0;
    }

    int sigaddset(sigset_t* set, int signo)
    {
        if (signo <= 0 || signo > NSIG)
        {
            errno = EINVAL;
            return -1;
        }

        *set |= (1 << (signo - 1));
        return 0;
    }

    int sigdelset(sigset_t* set, int signo)
    {
        if (signo <= 0 || signo > NSIG)
        {
            errno = EINVAL;
            return -1;
        }

        *set &= ~(1 << (signo - 1));
        return 0;
    }

    int sigismember(const sigset_t* set, int signo)
    {
        if (signo <= 0 || signo > NSIG)
        {
            errno = EINVAL;
            return -1;
        }

        return (*set & (1 << (signo - 1))) > 0;
    }
}