/*
 * This code is stolen from somewhere and adjusted for other purposes
 */
#include <sys/capability.h>

#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
#include <pthread.h>
#include <err.h>
#include <getopt.h>
#include <fcntl.h>
#include <sys/time.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>

#define N_ITER 1000000
//#define N_ITER 10000
#define FILENAME "footest"
#define TYPE_RDONLY 1
#define TYPE_RDWR 2

int ttype = TYPE_RDONLY;

int capped_fd;
int uncapped_fd;
int read_fd;


void *
dup2_worker(void *arg)
{
	int i, fd, n;

	for (i = 0; i < N_ITER; i++) {
		if (dup2(capped_fd, read_fd) < 0)
			err(1, "dup2");
	}
	return (NULL);
}

void *
read_worker(void *arg)
{
	char buf[100];
	int i;

	for (i = 0; i < N_ITER; i++) {
		if (read(read_fd, buf, 100) == -1) {
			switch (errno) {
			case EAGAIN:
			case ENOTCAPABLE:
				break;
			default:
				printf("%d\n", errno);
			}
		} else {
			printf("read\n");
		}
	}

	return (NULL);
}

double
now() {
	struct timeval tv;

	gettimeofday(&tv, NULL);
	return tv.tv_sec + (double)(tv.tv_usec) / 1000000;
}

int
main(int argc, char **argv) 
{
	pthread_t *threads;
	int n_threads = 8, i;
	double t1, t2;
	cap_rights_t rights;
	int pipe_fd[2];

	capped_fd = open(FILENAME, O_RDWR | O_CREAT | O_TRUNC, 0644);
	if (capped_fd < 0)
		err(1, "Cannot create %s", FILENAME);

	cap_rights_init(&rights, 0);
	if (cap_rights_limit(capped_fd, &rights) < 0)
		err(1, "cap_rights_limit");

	if (pipe2(pipe_fd, O_NONBLOCK) < 0)
		err(1, "pipe");

	uncapped_fd = pipe_fd[0];
	read_fd = pipe_fd[1] + 1;
	dup2(capped_fd, read_fd);

	while ((i = getopt(argc, argv, "n:t:h")) != -1) {
		switch (i) {
		case 'n':
			n_threads = atoi(optarg);
			break;
		case 't':
			if (strcmp(optarg, "r") == 0)
				ttype = TYPE_RDONLY;
			else if (strcmp(optarg, "w") == 0)
				ttype = TYPE_RDWR;
			else
				errx(1, "Unknown type: %s", optarg);
			break;
		case 'h':
			printf("usage: %s [-n n_threads] [-t r|w]\n", argv[0]);
			return 0;
		}

	}
	threads = malloc(sizeof(*threads) * n_threads);
	printf("%d threads, %d operations/thread\n", n_threads, N_ITER);

	pthread_create(&threads[0], NULL, dup2_worker, NULL);

	t1 = now();
	for (i = 1; i < n_threads; i++) {
		if (pthread_create(&threads[i], NULL, read_worker, NULL) != 0)
			err(1, "pthread_create failed");
	}

	for (i = 0; i < n_threads; i++)
		pthread_join(threads[i], NULL);

	t2 = now();
	unlink(FILENAME);

	printf("%u operations done in %0.1lf seconds: %0.1lf ops/s\n", n_threads * N_ITER, t2-t1, (n_threads * N_ITER) / (t2-t1));
}