Cope with glibc too old to have epoll_create1().

tglsfdc · tglsfdc · commit 82ebbeb0abfe · 2017-04-27T17:13:53.000-04:00
Commit fa31b6f supposed that we didn't have to worry about that anymore, but it seems that RHEL5 is like that, and that's still a supported platform. Put back the prior coding under an #ifdef, adding an explicit fcntl() to retain the desired CLOEXEC property. Discussion: https://postgr.es/m/12307.1493325329@sss.pgh.pa.us
diff --git a/src/backend/storage/ipc/latch.c b/src/backend/storage/ipc/latch.c
@@ -565,9 +565,18 @@ CreateWaitEventSet(MemoryContext context, int nevents)
 	set->nevents_space = nevents;
 
 #if defined(WAIT_USE_EPOLL)
+#ifdef EPOLL_CLOEXEC
 	set->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
 	if (set->epoll_fd < 0)
 		elog(ERROR, "epoll_create1 failed: %m");
+#else
+	/* cope with ancient glibc lacking epoll_create1 (e.g., RHEL5) */
+	set->epoll_fd = epoll_create(nevents);
+	if (set->epoll_fd < 0)
+		elog(ERROR, "epoll_create failed: %m");
+	if (fcntl(set->epoll_fd, F_SETFD, FD_CLOEXEC) == -1)
+		elog(ERROR, "fcntl(F_SETFD) failed on epoll descriptor: %m");
+#endif   /* EPOLL_CLOEXEC */
 #elif defined(WAIT_USE_WIN32)
 
 	/*
