kernel: add /dev/null polling test

Bug: 13965

src/tests/system/kernel/Jamfile

@@ -51,6 +51,8 @@ SimpleTest port_wakeup_test_9 : port_wakeup_test_9.cpp ;
 
 SimpleTest mmap_resize_test : mmap_resize_test.cpp ;
 
+SimpleTest null_poll_test : null_poll_test.cpp ;
+
 SimpleTest reserved_areas_test : reserved_areas_test.cpp ;
 
 SimpleTest select_check : select_check.cpp ;

src/tests/system/kernel/null_poll_test.cpp

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2018, Xiang Fan, [email protected].
+ * Distributed under the terms of the MIT License.
+ */
+
+#include <stdio.h>
+#include <poll.h>
+
+
+int main()
+{
+	FILE* f = fopen("/dev/null", "w");
+	printf("f=%p\n", f);
+	int fd = fileno(f);
+	printf("fd=%d\n", fd);
+
+	struct pollfd pfd;
+	pfd.fd = fd;
+	pfd.events = POLLOUT;
+	pfd.revents = 0;
+
+	int rv = poll(&pfd, 1, -1);
+	printf("rv=%d\n", rv);
+	if (rv <= 0)
+		return 1;
+	printf("events=%08x revents=%08x\n", pfd.events, pfd.revents);
+	if (pfd.revents != POLLOUT)
+		return 2;
+
+	return 0;
+}