static int tuntap_open_tramp()

in os-Linux/drivers/tuntap_user.c [62:126]

• 58 lines of code
• 7 McCabe index (conditional complexity)

static int tuntap_open_tramp(char *gate, int *fd_out, int me, int remote,
			     char *buffer, int buffer_len, int *used_out)
{
	struct tuntap_pre_exec_data data;
	char version_buf[sizeof("nnnnn\0")];
	char *argv[] = { "uml_net", version_buf, "tuntap", "up", gate,
			 NULL };
	char buf[CMSG_SPACE(sizeof(*fd_out))];
	struct msghdr msg;
	struct cmsghdr *cmsg;
	struct iovec iov;
	int pid, n, err;

	sprintf(version_buf, "%d", UML_NET_VERSION);

	data.stdout_fd = remote;
	data.close_me = me;

	pid = run_helper(tuntap_pre_exec, &data, argv);

	if (pid < 0)
		return pid;

	close(remote);

	msg.msg_name = NULL;
	msg.msg_namelen = 0;
	if (buffer != NULL) {
		iov = ((struct iovec) { buffer, buffer_len });
		msg.msg_iov = &iov;
		msg.msg_iovlen = 1;
	}
	else {
		msg.msg_iov = NULL;
		msg.msg_iovlen = 0;
	}
	msg.msg_control = buf;
	msg.msg_controllen = sizeof(buf);
	msg.msg_flags = 0;
	n = recvmsg(me, &msg, 0);
	*used_out = n;
	if (n < 0) {
		err = -errno;
		printk(UM_KERN_ERR "tuntap_open_tramp : recvmsg failed - "
		       "errno = %d\n", errno);
		return err;
	}
	helper_wait(pid);

	cmsg = CMSG_FIRSTHDR(&msg);
	if (cmsg == NULL) {
		printk(UM_KERN_ERR "tuntap_open_tramp : didn't receive a "
		       "message\n");
		return -EINVAL;
	}
	if ((cmsg->cmsg_level != SOL_SOCKET) ||
	   (cmsg->cmsg_type != SCM_RIGHTS)) {
		printk(UM_KERN_ERR "tuntap_open_tramp : didn't receive a "
		       "descriptor\n");
		return -EINVAL;
	}
	*fd_out = ((int *) CMSG_DATA(cmsg))[0];
	os_set_exec_close(*fd_out);
	return 0;
}