From 6b0449a990ed1fdd7fbf01663db16ed39c1d9696 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Vladim=C3=ADr=20=C4=8Cun=C3=A1t?= <vladimir.cunat@nic.cz>
Date: Mon, 7 Oct 2019 14:16:56 +0200
Subject: [PATCH] daemon/main: file-descriptor count limit: soft->hard

---
 NEWS          |  4 ++--
 daemon/main.c | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/NEWS b/NEWS
index 0c3a728d4..575082b23 100644
--- a/NEWS
+++ b/NEWS
@@ -3,10 +3,10 @@ Knot Resolver ??
 
 Improvements
 ------------
-- increase file-descriptor count limits to 1M by default
+- increase file-descriptor count limit to maximum allowed value (hard limit)
 
 
-Knot Resolver 4.2.2 (2019-10-dd)
+Knot Resolver 4.2.2 (2019-10-07)
 ================================
 
 Bugfixes
diff --git a/daemon/main.c b/daemon/main.c
index 0678f7e88..5501d9821 100644
--- a/daemon/main.c
+++ b/daemon/main.c
@@ -37,6 +37,7 @@
 #include <signal.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/resource.h>
 #include <unistd.h>
 
 #include <lua.h>
@@ -740,6 +741,23 @@ int main(int argc, char **argv)
 		args.config = "config";
 	}
 
+	/* File-descriptor count limit: soft->hard. */
+	struct rlimit rlim;
+	ret = getrlimit(RLIMIT_NOFILE, &rlim);
+	if (ret == 0 && rlim.rlim_cur != rlim.rlim_max) {
+		kr_log_verbose("[system] increasing file-descriptor limit: %ld -> %ld\n",
+				(long)rlim.rlim_cur, (long)rlim.rlim_max);
+		rlim.rlim_cur = rlim.rlim_max;
+		ret = setrlimit(RLIMIT_NOFILE, &rlim);
+	}
+	if (ret) {
+		kr_log_error("[system] failed to get or set file-descriptor limit: %s\n",
+				strerror(errno));
+	} else if (rlim.rlim_cur < 1024*1024) {
+		kr_log_info("[system] warning: hard limit for number of file-descriptors is only %ld but recommended value is 1048576\n",
+				rlim.rlim_cur);
+	}
+
 	/* Connect forks with local socket */
 	fd_array_t ipc_set;
 	array_init(ipc_set);
-- 
2.47.2