File util-linux-agetty-smart-reload-02.patch of Package python-libmount.31381

Backport, partial rewrite.
From 36c55a89871d836a9c6a2832151f0ca907e83ea0 Mon Sep 17 00:00:00 2001
From: Stanislav Brabec <sbrabec@suse.cz>
Date: Wed, 10 Oct 2018 19:26:27 +0200
Subject: [PATCH 02/14] agetty: Watch only protocol requested by issue escapes

To decrease number of reloads, watch only protocol requested by \4 and \6
escapes in issue file.

Signed-off-by: Stanislav Brabec <sbrabec@suse.cz>
---
 term-utils/agetty.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

Index: util-linux-2.31.1/term-utils/agetty.c
===================================================================
--- util-linux-2.31.1.orig/term-utils/agetty.c
+++ util-linux-2.31.1/term-utils/agetty.c
@@ -146,6 +146,7 @@
 # define AGETTY_RELOAD_FDNONE	-2			/* uninitialized fd */
 static int inotify_fd = AGETTY_RELOAD_FDNONE;
 static int netlink_fd = AGETTY_RELOAD_FDNONE;
+static __u32 netlink_groups;
 #endif
 
 /*
@@ -1537,7 +1538,7 @@ static void open_netlink(void)
 	if (sock >= 0) {
 		addr.nl_family = AF_NETLINK;
 		addr.nl_pid = getpid();
-		addr.nl_groups = RTMGRP_IPV4_IFADDR | RTMGRP_IPV6_IFADDR;
+		addr.nl_groups = netlink_groups;
 		if (bind(sock, (struct sockaddr *)&addr, sizeof(addr)) < 0)
 			close(sock);
 		else
@@ -1662,6 +1663,9 @@ static void print_issue_file(struct opti
 {
 #ifdef	ISSUE
 	FILE *fd;
+#ifdef AGETTY_RELOAD
+	netlink_groups = 0;
+#endif
 #endif
 	if ((op->flags & F_NONL) == 0) {
 		/* Issue not in use, start with a new line. */
@@ -1694,6 +1698,10 @@ static void print_issue_file(struct opti
 		}
 		fclose(fd);
 	}
+#ifdef AGETTY_RELOAD
+	if (netlink_groups != 0)
+		open_netlink();
+#endif
 #endif	/* ISSUE */
 }
 
@@ -2483,13 +2491,10 @@ static void output_special_char(unsigned
 	case '6':
 	{
 		sa_family_t family = c == '4' ? AF_INET : AF_INET6;
+		netlink_groups |= c == '4' ? RTMGRP_IPV4_IFADDR : RTMGRP_IPV6_IFADDR;
 		struct ifaddrs *addrs = NULL;
 		char iface[128];
 
-#ifdef AGETTY_RELOAD
-		open_netlink();
-#endif
-
 		if (getifaddrs(&addrs))
 			break;