/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */#include <iostream>#include <unistd.h>#include <linux/bpf.h>#include <linux/btf.h>#include <bpf/libbpf.h>#include <bpf/bpf.h>#include <bpf/btf.h>#include "test_core_extern.skel.h" template <typename T>class Skeleton {private:	T *skel;public:	Skeleton(): skel(nullptr) { } 	~Skeleton() { if (skel) T::destroy(skel); } 	int open(const struct bpf_object_open_opts *opts = nullptr)	{		int err; 		if (skel)			return -EBUSY; 		skel = T::open(opts);		err = libbpf_get_error(skel);		if (err) {			skel = nullptr;			return err;		} 		return 0;	} 	int load() { return T::load(skel); } 	int attach() { return T::attach(skel); } 	void detach() { return T::detach(skel); } 	const T* operator->() const { return skel; } 	T* operator->() { return skel; } 	const T *get() const { return skel; }}; static void dump_printf(void *ctx, const char *fmt, va_list args){} static void try_skeleton_template(){	Skeleton<test_core_extern> skel;	std::string prog_name;	int err;	LIBBPF_OPTS(bpf_object_open_opts, opts); 	err = skel.open(&opts);	if (err) {		fprintf(stderr, "Skeleton open failed: %d\n", err);		return;	} 	skel->data->kern_ver = 123;	skel->data->int_val = skel->data->ushort_val; 	err = skel.load();	if (err) {		fprintf(stderr, "Skeleton load failed: %d\n", err);		return;	} 	if (!skel->kconfig->CONFIG_BPF_SYSCALL)		fprintf(stderr, "Seems like CONFIG_BPF_SYSCALL isn't set?!\n"); 	err = skel.attach();	if (err) {		fprintf(stderr, "Skeleton attach failed: %d\n", err);		return;	} 	prog_name = bpf_program__name(skel->progs.handle_sys_enter);	if (prog_name != "handle_sys_enter")		fprintf(stderr, "Unexpected program name: %s\n", prog_name.c_str()); 	bpf_link__destroy(skel->links.handle_sys_enter);	skel->links.handle_sys_enter = bpf_program__attach(skel->progs.handle_sys_enter); 	skel.detach(); 	/* destructor will destroy underlying skeleton */} int main(int argc, char *argv[]){	struct btf_dump_opts opts = { };	struct test_core_extern *skel;	struct btf *btf;	int fd; 	try_skeleton_template(); 	/* libbpf.h */	libbpf_set_print(NULL); 	/* bpf.h */	bpf_prog_get_fd_by_id(0); 	/* btf.h */	btf = btf__new(NULL, 0);	if (!libbpf_get_error(btf))		btf_dump__new(btf, dump_printf, nullptr, &opts); 	/* BPF skeleton */	skel = test_core_extern__open_and_load();	test_core_extern__destroy(skel); 	fd = bpf_enable_stats(BPF_STATS_RUN_TIME);	if (fd < 0)		std::cout << "FAILED to enable stats: " << fd << std::endl;	else		::close(fd); 	std::cout << "DONE!" << std::endl; 	return 0;}