#include <cstdio>
#include <cstring>
#include <filesystem>
#include <fstream>
#include <functional>
#include <iostream>
#include <memory>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <unistd.h>
 
namespace fs = std::filesystem;
 
void print_entry_type(std::filesystem::directory_entry const& entry) {
    std::cout << entry.path() << ": ";
    if (!entry.exists()) std::cout << "does not exist ";
    if (entry.is_block_file()) std::cout << "is a block device ";
    if (entry.is_character_file()) std::cout << "is a character device ";
    if (entry.is_directory()) std::cout << "is a directory ";
    if (entry.is_fifo()) std::cout << "is a named IPC pipe ";
    if (entry.is_regular_file()) std::cout << "is a regular file ";
    if (entry.is_socket()) std::cout << "is a named IPC socket ";
    if (entry.is_symlink()) std::cout << "(a symlink) ";
    if (entry.is_other()) std::cout << "(an `other` file) ";
    std::cout <<'\n';
}
 
template <typename Type, typename Fun>
class scoped_cleanup {
    std::unique_ptr<Type, std::function<void(const Type*)>> u;
  public:
    scoped_cleanup(Type* ptr, Fun fun) : u{ptr, std::move(fun)} {}
};
 
int main()
{
    // create files of different kinds
    std::filesystem::current_path(fs::temp_directory_path());
    const std::filesystem::path sandbox{"sandbox"};
    scoped_cleanup remove_all_at_exit{&sandbox, [](const fs::path* p) {
        std::cout << "cleanup: remove_all(" << *p << ")\n";
        fs::remove_all(*p);
    } };
    std::filesystem::create_directory(sandbox);
    std::ofstream{sandbox/"file"}; // creates a regular file
    std::filesystem::create_directory(sandbox/"dir");
 
    mkfifo((sandbox/"pipe").string().data(), 0644);
    struct sockaddr_un addr; addr.sun_family = AF_UNIX;
 
    std::strcpy(addr.sun_path, (sandbox/"sock").string().data());
    int fd {socket(PF_UNIX, SOCK_STREAM, 0)};
    scoped_cleanup close_socket_at_exit{&fd, [](const int* f) {
        std::cout << "cleanup: close socket #" << *f << '\n';
        close(*f);
    } };
    bind(fd, reinterpret_cast<sockaddr*>(std::addressof(addr)), sizeof addr);
 
    fs::create_symlink("file", sandbox/"symlink");
 
    for (std::filesystem::directory_entry entry: fs::directory_iterator(sandbox)) {
        print_entry_type(entry);
    }
 
    // direct calls to status:
    for (const char* str: {"/dev/null", "/dev/cpu", "/usr/include/c++",
                           "/usr/include/asm", "/usr/include/time.h"}) {
        print_entry_type(fs::directory_entry{str});
    }
 
}   // cleanup via `scoped_cleanup` objects