#include <stdio.h>
#include <sched.h>
#include <signal.h>
#include <unistd.h>
#include <errno.h>
#include <malloc.h>

#define CLONE_NEWPID		0x20000000
#ifndef __NR_gettid
#ifdef __x86__
#define __NR_gettid		224
#elif __s390__
#define __NR_gettid		236
#else
#error __NR_gettid undefined
#endif
#endif

#ifndef __NR_clone_with_pids
#ifdef __x86__
#define __NR_clone_with_pids	335
#elif __s390__
#define __NR_clone_with_pids	332
#else
#error __NR_clone_with_pids undefined
#endif
#endif
/*
 * TODO: getpid() in child returns pid of parent for some reason gettid()
 * 	 returns correct pid (i.e 1 if CLONE_NEWPID or 19799 otherwise)
 */
int gettid()
{
	int rc;

	rc = syscall(__NR_gettid, 0, 0, 0);
	if (rc < 0) {
		printf("rc %d, errno %d\n", rc, errno);
		fflush(stdout);
	}
	return rc;
}

struct target_pid_set {
	int num_pids;
	pid_t *target_pids;
	unsigned long flags;
};

main()
{
	int rc;
	int clone_flags;
	struct target_pid_set pid_set;
	int stacksize = 4 * getpagesize();
	void *childsp, *topstack;
	
	int pids[1] = { 19799 };
	
	childsp = malloc(stacksize);
	if (!childsp)
		return -1;
	topstack = childsp + stacksize;

	pid_set.num_pids = 1;
	pid_set.target_pids = &pids[0];
	pid_set.flags = 0;

	//clone_flags = (CLONE_NEWPID| CLONE_FS | CLONE_FILES | SIGCHLD);
	clone_flags = ( CLONE_FS | CLONE_FILES | SIGCHLD);

	printf("Parent: Call clone_with_pids() for &pid_set %p\n", &pid_set);

	rc = syscall(__NR_clone_with_pids, topstack, clone_flags, NULL,
			NULL, &pid_set);
			//NULL, NULL);
	if (rc == 0) {
		printf("Child: tid %d\n", gettid());
		_exit(0);
	} else if (rc > 0) {
		printf("Parent: child pid %d\n", rc);
		_exit(0);
	} else {
		printf("myclone() failed, rc %d, errno %d\n", rc, errno);
	}
}