#include <errno.h>
#include <stdio.h>
#include <fcntl.h>
#include <signal.h>
#include <unistd.h>
#ifdef __APPLE__
#define SIGRTMIN SIGUSR1
#endif

typedef long long i64;
typedef int i32;
typedef char u8;
typedef ssize_t isize;

volatile static i32 weDone = 0;
volatile static i32 mode = -1;

static void handler(int signal) {
    if (signal == SIGTERM) {
        weDone = 1;
    } else {
        mode = signal - SIGRTMIN;
    }
}

isize myread(i32 fd, void *buf, isize size) {
    isize done = 0;
    while (done < size) {
        errno = 0;
        isize thisTime = read(fd, (u8*)buf + done, size - done);
        if (thisTime == -1) {
            if (errno == EINTR) {
                continue;
            }
            return -1;
        }
        if (thisTime == 0) {
            return 0;
        }
        done += thisTime;
    }
}

i32 main(i32 argc, u8 **argv) {
    i32 nfiles = argc - 1;
    i32 fds[nfiles];
    i64 sum[nfiles];
    struct sigaction act = {};
    act.sa_handler = handler;
    act.sa_flags = 0;
    sigset_t blockAll;
    sigset_t listeningSignals;
    sigfillset(&blockAll);
    sigfillset(&listeningSignals);
    for (i32 i = 0; i < nfiles; i++) {
        sigdelset(&listeningSignals, SIGRTMIN + i);
    }
    sigdelset(&listeningSignals, SIGTERM);
    sigemptyset(&act.sa_mask);

    for (i32 i = 0; i < nfiles; i++) {
        fds[i] = -1;
        sum[i] = 0;
        sigaction(SIGRTMIN + i, &act, NULL);
    }
    sigaction(SIGTERM, &act, NULL);
    sigprocmask(SIG_SETMASK, &blockAll, NULL);
    printf("%d\n", getpid());
    for (;;) {
        if (weDone) {
            for (i32 i = 0; i < nfiles; i++) {
                printf("%lld\n", sum[i]);
            }
            return 0;
        }
        if (mode == -1) {
            sigsuspend(&listeningSignals);
            continue;
        }
        if (fds[mode] == -1) {
            fds[mode] = open(argv[mode + 1], O_RDONLY);
        }
        if (fds[mode] == -2) {
            mode = -1;
            continue;
        }
        u8 buf[16];
        sigprocmask(SIG_SETMASK, &listeningSignals, NULL);
        isize rd = myread(fds[mode], &buf, 16);
        sigprocmask(SIG_SETMASK, &blockAll, NULL);
        if (rd == -1) {
            fds[mode] = -2;
            mode = -1;
            continue;
        }
        if (rd != 16) {
            continue;
        }
        i64 dat;
        sscanf(buf, "%lld", &dat);
        sum[mode] += dat;
    }
}