replace_fd
err = replace_fd(COREDUMP_PIDFD_NUMBER, pidfs_file, 0);
err = replace_fd(0, files[0], 0);
error = replace_fd(new_fd, file, o_flags);
extern int replace_fd(unsigned fd, struct file *file, unsigned flags);
replace_fd(n - 1, devnull, 0);
replace_fd(n - 1, devnull, 0);
attr.replace_bpf_fd = OPTS_GET(opts, replace_fd, 0);
int replace_fd;