#include <errno.h>
#include <stdio.h>
#include <pthread.h>

int main(int argc, char *argv[]) {
	pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
	pthread_mutexattr_t attr;
	int ret;

	ret = pthread_mutexattr_init(&attr);
	if (ret) {
		printf("pthread_mutexattr_init failed\n");
		return 0;
	}

	ret = pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
	if (ret) {
		printf("pthread_mutexattr_settype failed\n");
		return 0;
	}

	ret = pthread_mutexattr_setprotocol(&attr, PTHREAD_PRIO_INHERIT);
	if (ret) {
		printf("pthread_mutexattr_setprotocol failed\n");
		return 0;
	}

	ret = pthread_mutex_init(&mutex, &attr);
	if (ret == ENOTSUP) {
		printf("pthread_mutex_init failed\n");
	}

	while (1) {
		fprintf(stderr, "lock... ");
		pthread_mutex_lock(&mutex);
		fprintf(stderr, "acquired... ");

		sleep(1);

		pthread_mutex_unlock(&mutex);
		fprintf(stderr, "released...\n");
	}

	pthread_mutex_destroy(&mutex);

	return 0;
}