From 60d9771c593e0702a892a4372443e63b38cdbcba Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Fri, 6 May 2016 13:29:26 +0200
Subject: core: rework how we flush incoming traffic when a socket unit goes
 down

Previously, we'd simply close and reopen the socket file descriptors. This is
problematic however, as we won't transition through the SOCKET_CHOWN state
then, and thus the file ownership won't be correct for the sockets.

Rework the flushing logic, and actually read any queued data from the sockets
for flushing, and accept any queued messages and disconnect them.
---
 src/basic/socket-util.c | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

(limited to 'src/basic/socket-util.c')

diff --git a/src/basic/socket-util.c b/src/basic/socket-util.c
index 0f38f9a0f3..c634f1d564 100644
--- a/src/basic/socket-util.c
+++ b/src/basic/socket-util.c
@@ -23,6 +23,7 @@
 #include <net/if.h>
 #include <netdb.h>
 #include <netinet/ip.h>
+#include <poll.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <stdio.h>
@@ -970,3 +971,42 @@ fallback:
 
         return (ssize_t) k;
 }
+
+int flush_accept(int fd) {
+
+        struct pollfd pollfd = {
+                .fd = fd,
+                .events = POLLIN,
+        };
+        int r;
+
+
+        /* Similar to flush_fd() but flushes all incoming connection by accepting them and immediately closing them. */
+
+        for (;;) {
+                int cfd;
+
+                r = poll(&pollfd, 1, 0);
+                if (r < 0) {
+                        if (errno == EINTR)
+                                continue;
+
+                        return -errno;
+
+                } else if (r == 0)
+                        return 0;
+
+                cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC);
+                if (cfd < 0) {
+                        if (errno == EINTR)
+                                continue;
+
+                        if (errno == EAGAIN)
+                                return 0;
+
+                        return -errno;
+                }
+
+                close(cfd);
+        }
+}
-- 
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