Function exec_copyin_data_fds

freebsd/kern/kern_exec.c:1224–1285

}

int
exec_copyin_data_fds(struct thread *td, struct image_args *args,
    const void *data, size_t datalen, const int *fds, size_t fdslen)
{
	struct filedesc *ofdp;
	const char *p;
	int *kfds;
	int error;

	memset(args, '\0', sizeof(*args));
	ofdp = td->td_proc->p_fd;
	if (datalen >= ARG_MAX || fdslen >= ofdp->fd_nfiles)
		return (E2BIG);
	error = exec_alloc_args(args);
	if (error != 0)
		return (error);

	args->begin_argv = args->buf;
	args->stringspace = ARG_MAX;

	if (datalen > 0) {
		/*
		 * Argument buffer has been provided. Copy it into the
		 * kernel as a single string and add a terminating null
		 * byte.
		 */
		error = copyin(data, args->begin_argv, datalen);
		if (error != 0)
			goto err_exit;
		args->begin_argv[datalen] = '\0';
		args->endp = args->begin_argv + datalen + 1;
		args->stringspace -= datalen + 1;

		/*
		 * Traditional argument counting. Count the number of
		 * null bytes.
		 */
		for (p = args->begin_argv; p < args->endp; ++p)
			if (*p == '\0')
				++args->argc;
	} else {
		/* No argument buffer provided. */
		args->endp = args->begin_argv;
	}

	/* Create new file descriptor table. */
	kfds = malloc(fdslen * sizeof(int), M_TEMP, M_WAITOK);
	error = copyin(fds, kfds, fdslen * sizeof(int));
	if (error != 0) {
		free(kfds, M_TEMP);
		goto err_exit;
	}
	error = fdcopy_remapped(ofdp, kfds, fdslen, &args->fdp);
	free(kfds, M_TEMP);
	if (error != 0)
		goto err_exit;

	return (0);