tests: Add test case for freeing source with pending data

tests/event-loop-test.c

@@ -22,6 +22,7 @@
 
 #include <stdlib.h>
 #include <assert.h>
+#include <unistd.h>
 #include "../src/wayland-server.h"
 #include "test-runner.h"
 
@@ -51,3 +52,72 @@ TEST(post_dispatch_check)
 	wl_event_source_remove(source);
 	wl_event_loop_destroy(loop);
 }
+
+struct free_source_context {
+	struct wl_event_source *source1, *source2;
+	int p1[2], p2[2];
+	int count;
+};
+
+static int
+free_source_callback(int fd, uint32_t mask, void *data)
+{
+	struct free_source_context *context = data;
+
+	context->count++;
+
+	/* Remove other source */
+	if (fd == context->p1[0]) {
+		wl_event_source_remove(context->source2);
+		context->source2 = NULL;
+	} else if (fd == context->p2[0]) {
+		wl_event_source_remove(context->source1);
+		context->source1 = NULL;
+	} else {
+		assert(0);
+	}
+
+	return 1;
+}
+
+TEST(free_source_with_data)
+{
+	struct wl_event_loop *loop = wl_event_loop_create();
+	struct free_source_context context;
+	int data;
+
+	/* This test is a little tricky to get right, since we don't
+	 * have any guarantee from the event loop (ie epoll) on the
+	 * order of which it reports events.  We want to have one
+	 * source free the other, but we don't know which one is going
+	 * to run first.  So we add two fd sources with a callback
+	 * that frees the other source and check that only one of them
+	 * run (and that we don't crash, of course).
+	 */
+
+	context.count = 0;
+	assert(pipe(context.p1) == 0);
+	assert(pipe(context.p2) == 0);
+	context.source1 =
+		wl_event_loop_add_fd(loop, context.p1[0], WL_EVENT_READABLE,
+				     free_source_callback, &context);
+	assert(context.source1);
+	context.source2 =
+		wl_event_loop_add_fd(loop, context.p2[0], WL_EVENT_READABLE,
+				     free_source_callback, &context);
+	assert(context.source2);
+
+	data = 5;
+	assert(write(context.p1[1], &data, sizeof data) == sizeof data);
+	assert(write(context.p2[1], &data, sizeof data) == sizeof data);
+
+	wl_event_loop_dispatch(loop, 0);
+
+	assert(context.count == 1);
+
+	if (context.source1)
+		wl_event_source_remove(context.source1);
+	if (context.source2)
+		wl_event_source_remove(context.source2);
+	wl_event_loop_destroy(loop);
+}