int copy_tree(const char *from, const char *to, bool merge);
int copy_tree_at(int fdf, const char *from, int fdt, const char *to, bool merge);
int copy_directory_fd(int dirfd, const char *to, bool merge);
int copy_tree(const char *from, const char *to, bool merge);
int copy_tree_at(int fdf, const char *from, int fdt, const char *to, bool merge);
int copy_directory_fd(int dirfd, const char *to, bool merge);