688 /*

   689  * recvfds() simply does not release GIL during blocking io operation because

   690  * command server is known to be single-threaded.

   691  *

   692  * Old systems such as Solaris don't provide CMSG_LEN, msg_control, etc.

   693  * Currently, recvfds() is not supported on these platforms.

   694  */

   695 #ifdef CMSG_LEN

   696 

   697 static ssize_t recvfdstobuf(int sockfd, int **rfds, void *cbuf, size_t cbufsize)

   698 {

   699 	char dummy[1];

   700 	struct iovec iov = {dummy, sizeof(dummy)};

   701 	struct msghdr msgh = {0};

   702 	struct cmsghdr *cmsg;

   703 

   704 	msgh.msg_iov = &iov;

   705 	msgh.msg_iovlen = 1;

   706 	msgh.msg_control = cbuf;

   707 	msgh.msg_controllen = (socklen_t)cbufsize;

   708 	if (recvmsg(sockfd, &msgh, 0) < 0)

   709 		return -1;

   710 

   711 	for (cmsg = CMSG_FIRSTHDR(&msgh); cmsg;

   712 	     cmsg = CMSG_NXTHDR(&msgh, cmsg)) {

   713 		if (cmsg->cmsg_level != SOL_SOCKET ||

   714 		    cmsg->cmsg_type != SCM_RIGHTS)

   715 			continue;

   716 		*rfds = (int *)CMSG_DATA(cmsg);

   717 		return (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int);

   718 	}

   719 

   720 	*rfds = cbuf;

   721 	return 0;

   722 }

   723 

   724 static PyObject *recvfds(PyObject *self, PyObject *args)

   725 {

   726 	int sockfd;

   727 	int *rfds = NULL;

   728 	ssize_t rfdscount, i;

   729 	char cbuf[256];

   730 	PyObject *rfdslist = NULL;

   731 

   732 	if (!PyArg_ParseTuple(args, "i", &sockfd))

   733 		return NULL;

   734 

   735 	rfdscount = recvfdstobuf(sockfd, &rfds, cbuf, sizeof(cbuf));

   736 	if (rfdscount < 0)

   737 		return PyErr_SetFromErrno(PyExc_OSError);

   738 

   739 	rfdslist = PyList_New(rfdscount);

   740 	if (!rfdslist)

   741 		goto bail;

   742 	for (i = 0; i < rfdscount; i++) {

   743 		PyObject *obj = PyLong_FromLong(rfds[i]);

   744 		if (!obj)

   745 			goto bail;

   746 		PyList_SET_ITEM(rfdslist, i, obj);

   747 	}

   748 	return rfdslist;

   749 

   750 bail:

   751 	Py_XDECREF(rfdslist);

   752 	return NULL;

   753 }

   754 

   755 #endif /* CMSG_LEN */

   756 

  1288 #ifdef CMSG_LEN

  1289 	{"recvfds", (PyCFunction)recvfds, METH_VARARGS,

  1290 	 "receive list of file descriptors via socket\n"},

  1291 #endif