--- /dev/null
+/* $OpenBSD: unp-write-closed.c,v 1.1.1.1 2024/06/28 21:07:27 bluhm Exp $ */
+/*
+ * Copyright (c) 2024 Vitaliy Makkoveev <mvs@openbsd.org>
+ * Copyright (c) 2024 Alenander Bluhm <bluhm@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/wait.h>
+
+#include <err.h>
+#include <errno.h>
+#include <signal.h>
+#include <unistd.h>
+
+sig_atomic_t done = 0;
+
+void
+handler(int sigraised)
+{
+ done = 1;
+}
+
+int
+main(int argc, char *argv[])
+{
+ int i, s[2], status;
+ pid_t pid;
+
+ if (signal(SIGPIPE, SIG_IGN) == SIG_ERR)
+ err(1, "signal pipe");
+ if (signal(SIGALRM, handler) == SIG_ERR)
+ err(1, "signal alrm");
+ alarm(30);
+
+ while (!done) {
+ if (socketpair(AF_UNIX, SOCK_STREAM, 0, s) < 0)
+ err(1, "socketpair");
+
+ switch ((pid = fork())) {
+ case -1:
+ err(1, "fork");
+ case 0:
+ if (close(s[0]) < 0)
+ err(1, "child close 0");
+ if (close(s[1]) < 0)
+ err(1, "child close 1");
+ return 0;
+ default:
+ if (close(s[1]) < 0)
+ err(1, "parent close 1");
+ for (i = 1000000; i > 0; i--) {
+ if (write(s[0], "1", 1) < 0)
+ break;
+ }
+ if (i <= 0)
+ errx(1, "write did not fail");
+ if (errno != EPIPE)
+ err(1, "write");
+ if (close(s[0]) < 0)
+ err(1, "parent close 1");
+ if (waitpid(pid, &status, 0) < 0)
+ err(1, "waitpid");
+ if (status != 0)
+ errx(1, "child status %d", status);
+ break;
+ }
+ }
+
+ return 0;
+}