From ebf57dfc03c9f3bda5ee065d45c28feb6ebb1c97 Mon Sep 17 00:00:00 2001
From: Dirk Engling <erdgeist@erdgeist.org>
Date: Fri, 30 Oct 2026 03:25:35 +0100
Subject: Reduce syscalls and add helper to count them

---
 tests/t_event.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

(limited to 'tests/t_event.c')

diff --git a/tests/t_event.c b/tests/t_event.c
index 5509f19..ad3948f 100644
--- a/tests/t_event.c
+++ b/tests/t_event.c
@@ -4,6 +4,7 @@
    $id$ */
 
 /* System */
+#include <fcntl.h>
 #include <string.h>
 #include <sys/socket.h>
 #include <sys/time.h>
@@ -205,6 +206,41 @@ static void case_unknown_descriptor(void) {
   CHECK_INT(event_del(4096), -1);
 }
 
+/* event_close exists so that the mechanisms which drop a closed descriptor
+   by themselves are not asked to do it twice. The one that keeps its own
+   list has to be told, and forgetting would leave the entry there to be
+   reported for ever, so what is checked here is the silence afterwards. */
+static void case_close_takes_it_out(void) {
+  int other[2], closed, count, i, strays = 0;
+
+  test_case("a closed descriptor is gone from the set and really closed");
+  pair_open();
+  CHECK(sv[0] != -1);
+  CHECK_INT(socketpair(AF_UNIX, SOCK_STREAM, 0, other), 0);
+  CHECK_INT(event_add(sv[0], EVENT_IN, 1), 0);
+  CHECK_INT(event_add(other[0], EVENT_IN, 2), 0);
+
+  closed = sv[0];
+  CHECK_INT(event_close(closed), 0);
+  sv[0] = -1;
+  CHECK_INT(fcntl(closed, F_GETFD), -1);
+
+  /* The survivor is made ready so the wait has something to come back with,
+     and anything left over from the closed one shows up beside it */
+  CHECK_INT((int)write(other[1], "x", 1), 1);
+  count = event_wait(ready, EVENTS, 200);
+  CHECK(count >= 1);
+  for (i = 0; i < count; ++i)
+    if (ready[i].fd != other[0])
+      ++strays;
+  CHECK_INT(strays, 0);
+
+  event_del(other[0]);
+  close(other[0]);
+  close(other[1]);
+  pair_close();
+}
+
 void test_event(void) {
   CHECK_INT(event_init(), 0);
   CHECK(event_mechanism() != NULL);
@@ -217,6 +253,7 @@ void test_event(void) {
   case_delete_from_the_middle();
   case_timeout();
   case_unknown_descriptor();
+  case_close_takes_it_out();
 
   event_deinit();
 }
-- 
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