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

#define _SDT_HAS_SEMAPHORES 1
#include "sdt.h"

#define SHARED 1
#include "bpf/libbpf_internal.h"

#define SEC(name) __attribute__((section(name), used))

#define BUF_SIZE 256

/* defined in urandom_read_aux.c */
void urand_read_without_sema(int iter_num, int iter_cnt, int read_sz);
/* these are coming from urandom_read_lib{1,2}.c */
void urandlib_read_with_sema(int iter_num, int iter_cnt, int read_sz);
void urandlib_read_without_sema(int iter_num, int iter_cnt, int read_sz);

int urandlib_api(void);
COMPAT_VERSION(urandlib_api_old, urandlib_api, LIBURANDOM_READ_1.0.0)
int urandlib_api_old(void);
int urandlib_api_sameoffset(void);

unsigned short urand_read_with_sema_semaphore SEC(".probes");

static noinline void urandom_read(int fd, int count)
{
        char buf[BUF_SIZE];
        int i;

        for (i = 0; i < count; ++i) {
                read(fd, buf, BUF_SIZE);

                /* trigger USDTs defined in executable itself */
                urand_read_without_sema(i, count, BUF_SIZE);
                STAP_PROBE3(urand, read_with_sema, i, count, BUF_SIZE);

                /* trigger USDTs defined in shared lib */
                urandlib_read_without_sema(i, count, BUF_SIZE);
                urandlib_read_with_sema(i, count, BUF_SIZE);
        }
}

static volatile bool parent_ready;

static void handle_sigpipe(int sig)
{
        parent_ready = true;
}

int main(int argc, char *argv[])
{
        int fd = open("/dev/urandom", O_RDONLY);
        int count = 4;
        bool report_pid = false;

        if (fd < 0)
                return 1;

        if (argc >= 2)
                count = atoi(argv[1]);
        if (argc >= 3) {
                report_pid = true;
                /* install SIGPIPE handler to catch when parent closes their
                 * end of the pipe (on the other side of our stdout)
                 */
                signal(SIGPIPE, handle_sigpipe);
        }

        /* report PID and wait for parent process to send us "signal" by
         * closing stdout
         */
        if (report_pid) {
                while (!parent_ready) {
                        fprintf(stdout, "%d\n", getpid());
                        fflush(stdout);
                }
                /* at this point stdout is closed, parent process knows our
                 * PID and is ready to trace us
                 */
        }

        urandom_read(fd, count);

        urandlib_api();
        urandlib_api_old();
        urandlib_api_sameoffset();

        close(fd);
        return 0;
}