Function recvfd

module/src/main/cpp/utils.cpp:249–300

}

static int recvfd(int sockfd) {
	int data, fd;
	ssize_t nr;
	struct iovec iov{};
	struct msghdr msgh{};

	/* Allocate a char buffer for the ancillary data. See the comments
	   in sendfd() */
	union {
		char buf[CMSG_SPACE(sizeof(int))];
		struct cmsghdr align;
	} controlMsg{};
	struct cmsghdr *cmsgp;

	/* The 'msg_name' field can be used to obtain the address of the
	   sending socket. However, we do not need this information. */

	msgh.msg_name = nullptr;
	msgh.msg_namelen = 0;

	/* Specify buffer for receiving real data */

	msgh.msg_iov = &iov;
	msgh.msg_iovlen = 1;
	iov.iov_base = &data; /* Real data is an 'int' */
	iov.iov_len = sizeof(int);

	/* Set 'msghdr' fields that describe ancillary data */

	msgh.msg_control = controlMsg.buf;
	msgh.msg_controllen = sizeof(controlMsg.buf);

	/* Receive real plus ancillary data; real data is ignored */

	nr = recvmsg(sockfd, &msgh, 0);
	if (nr == -1) return -1;

	cmsgp = CMSG_FIRSTHDR(&msgh);

	/* Check the validity of the 'cmsghdr' */

	if (cmsgp == nullptr || cmsgp->cmsg_len != CMSG_LEN(sizeof(int)) ||
		cmsgp->cmsg_level != SOL_SOCKET || cmsgp->cmsg_type != SCM_RIGHTS) {
		errno = EINVAL;
		return -1;
	}

	/* Return the received file descriptor to our caller */

	memcpy(&fd, CMSG_DATA(cmsgp), sizeof(int));
	return fd;
}

static int getKernelVersion() {
	struct utsname un{};