#include <sys/types.h>
#include <sys/mman.h>
#include <sys/wait.h>

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

int
main()
{
	pthread_mutexattr_t ma;
	pthread_mutex_t *m;
	void *ptr;
	pid_t pid, wpid;
	int status;
	int ret;

	ptr = mmap(NULL, sizeof(pthread_mutex_t), PROT_READ|PROT_WRITE,
	    MAP_SHARED|MAP_ANON, -1 /* fd */, 0);
	if (ptr == MAP_FAILED) {
		perror("mmap");
		return (1);
	}

	pthread_mutexattr_init(&ma);
	pthread_mutexattr_settype(&ma, PTHREAD_MUTEX_ERRORCHECK);
	pthread_mutexattr_setpshared(&ma, PTHREAD_PROCESS_SHARED);
	pthread_mutexattr_setrobust(&ma, PTHREAD_MUTEX_ROBUST);
	ret = pthread_mutex_init(ptr, &ma);
	if (ret != 0) {
		perror("pthread_mutex_init");
		return (1);
	}

	m = ptr;

	pid = fork();
	if (pid == 0) {
		pthread_mutex_lock(m);
		_exit(0);
	}
	if (pid == -1) {
		perror("fork");
		return (1);
	}

	wpid = waitpid(pid, &status, 0);
	if (wpid != pid) {
		perror("waitpid");
		return (1);
	}

	pthread_mutex_destroy(m);
	pthread_mutexattr_destroy(&ma);
	munmap(ptr, sizeof(pthread_mutex_t));

	return (0);
}