#define _GNU_SOURCE
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <err.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>

#ifndef SYS_translate_pid
#ifdef __x86_64__
#define SYS_translate_pid 333
#endif
#endif

pid_t translate_pid(pid_t pid, int source, int target) {
	return syscall(SYS_translate_pid, pid, source, target);
}

int main(int argc, char **argv) {
	int pid, source, target;
	char buf[64];

	if (argc != 4)
		errx(1, "usage: %s <pid> <source|-1> <traget|-1>", argv[0]);

	pid = atoi(argv[1]);
	source = atoi(argv[2]);
	target = atoi(argv[3]);

	if (source >= 0) {
		sprintf(buf, "/proc/%d/ns/pid", source);
		source = open(buf, O_RDONLY);
		if (source < 0)
			err(2, "source %s", buf);
	}

	if (target >= 0) {
		sprintf(buf, "/proc/%d/ns/pid", target);
		target = open(buf, O_RDONLY);
		if (target < 0)
			err(2, "target %s", buf);
	}


	pid = translate_pid(pid, source, target);
	if (pid < 0)
		err(2, "translate");

	printf("%d\n", pid);
	return 0;
}