#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <linux/aio.h>
#include <signal.h>
#include <pthread.h>

#define USE_AIO
int TEST_SIGNAL;
char *buffer;
int fd;
pthread_t thread;

#ifndef USE_AIO
int readFile(int fd, char* buffer, int size) {
    return read(fd, buffer, size);
}
#else
int readFile(int fd, char* buffer, int size) {
    struct aiocb cb;
    struct sigevent sigevt;
    sigset_t set, oset;
    siginfo_t info;
    int error;

    cb.aio_fildes = fd;
    cb.aio_offset = 0;
    cb.aio_buf = buffer;
    cb.aio_nbytes = size;
    sigevt.sigev_notify = SIGEV_SIGNAL;
    sigevt.sigev_signo = TEST_SIGNAL;
    sigevt.sigev_value = (sigval_t) 42;
    cb.aio_sigevent = sigevt;

    sigemptyset(&set);
    sigaddset(&set, TEST_SIGNAL);
    //  error = sigprocmask(SIG_BLOCK, &set, &oset);
    error = pthread_sigmask(SIG_BLOCK, &set, &oset);
    if (error != 0) {
	perror("Error setting mainthread signal mask");
    }

    printf("Reader pid: %d\n", getpid());
    pthread_sigmask(SIG_BLOCK, NULL, &oset);
    //  sigprocmask(SIG_BLOCK, NULL, &oset);
    if (sigismember(&oset, TEST_SIGNAL)) {
	printf("We are blocking TEST_SIGNAL\n");
    }
    aio_read(&cb);
    pthread_sigmask(SIG_BLOCK, NULL, &oset);
    //  sigprocmask(SIG_BLOCK, NULL, &oset);
    if (sigismember(&oset, TEST_SIGNAL)) {
	printf("We are still blocking TEST_SIGNAL in process %d\n", getpid());
    }
    //    sigwaitinfo(&set, &info);
    //    printf("The magic number is: %d\n", info.si_value.sival_int);
    aio_return(&cb);
    //  printf("Signalling thread\n");
    //  pthread_kill(thread, TEST_SIGNAL);
    return 1;
}

void* setupWaiter(void *args) {
    sigset_t set, oset;
    siginfo_t info;
    int error;

    printf("Waiter pid: %d\n", getpid());
    sigemptyset(&set);
    sigaddset(&set, TEST_SIGNAL);
    error = pthread_sigmask(SIG_BLOCK, &set, &oset);
    if (error != 0) {
	perror("Error setting thread signal mask");
    }
    pthread_sigmask(SIG_BLOCK, NULL, &oset);
    if (sigismember(&oset, TEST_SIGNAL)) {
	printf("Waiter is also bocking TEST_SIGNAL\n");
    }
    sigwaitinfo(&set, &info);
    printf("The magic number is: %d\n", info.si_value.sival_int);
    printf("Contents: %s\n", buffer);
    close(fd);
    return 0;
}
#endif

int main(int argc, char** argv) {
    void *an_answer;
    int size;
    int answer;
    struct stat fd_stat;
    TEST_SIGNAL = SIGRTMIN;
    printf("Argc: %d\n", argc);
    printf("PID: %d\n", getpid());
    fd = open("test.c", O_RDONLY);
    answer = fstat(fd, &fd_stat);
    if (answer != 0) {
	perror("Error stating file");
    } else {
	size = (int) fd_stat.st_size;
	printf("size: %d\n", size);
    }
    buffer = (char*) malloc((size+1)*sizeof(char));
#ifdef USE_AIO
    {
	pthread_attr_t attrib;
	pthread_attr_init(&attrib);
	pthread_create(&thread, &attrib, &setupWaiter, NULL);
    }
#endif
    answer = readFile(fd, buffer, size);
#ifndef USE_AIO
    printf("Contents: %s\n", buffer);
    close(fd);
#else
    pthread_join(thread, &an_answer);
#endif
    return answer;
}