--- /dev/null
+/* $OpenBSD: ungc.c,v 1.1 2021/06/01 13:13:10 mvs Exp $ */
+
+/*
+ * Copyright (c) 2021 Vitaliy Makkoveev <mvs@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/time.h>
+#include <sys/un.h>
+#include <stdio.h>
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+union msg_control{
+ struct cmsghdr cmsgh;
+ char control[CMSG_SPACE(sizeof(int)*2)];
+};
+
+int main(int argc, char *argv[])
+{
+ struct timespec ts_start, ts_now, ts_time;
+ union msg_control msg_control;
+ int iov_buf;
+ struct iovec iov;
+ struct msghdr msgh;
+ struct cmsghdr *cmsgh;
+ int s[2];
+ int infinite = 0;
+
+ if (argc > 1 && !strcmp(argv[1], "--infinite"))
+ infinite = 1;
+
+ if (!infinite)
+ if (clock_gettime(CLOCK_BOOTTIME, &ts_start) <0)
+ err(1, "clock_gettime");
+
+ while (1) {
+ if (socketpair(AF_UNIX, SOCK_STREAM|O_NONBLOCK, 0, s) < 0)
+ err(1, "socketpair");
+
+ iov_buf = 0;
+ iov.iov_base = &iov_buf;
+ iov.iov_len = sizeof(iov_buf);
+ msgh.msg_control = msg_control.control;
+ msgh.msg_controllen = sizeof(msg_control.control);
+ msgh.msg_iov = &iov;
+ msgh.msg_iovlen = 1;
+ msgh.msg_name = NULL;
+ msgh.msg_namelen = 0;
+ cmsgh = CMSG_FIRSTHDR(&msgh);
+ cmsgh->cmsg_len = CMSG_LEN(sizeof(int) * 2);
+ cmsgh->cmsg_level = SOL_SOCKET;
+ cmsgh->cmsg_type = SCM_RIGHTS;
+ *((int *)CMSG_DATA(cmsgh) + 0) = s[0];
+ *((int *)CMSG_DATA(cmsgh) + 1) = s[1];
+
+ if (sendmsg(s[0], &msgh, 0) < 0) {
+ if (errno != EMFILE)
+ err(1, "sendmsg");
+ }
+
+ close(s[0]);
+ close(s[1]);
+
+ if (!infinite) {
+ if (clock_gettime(CLOCK_BOOTTIME, &ts_now) <0)
+ err(1, "clock_gettime");
+
+ timespecsub(&ts_now, &ts_start, &ts_time);
+ if (ts_time.tv_sec >= 20)
+ break;
+ }
+ }
+
+ return 0;
+}