[PATCH weston] systemd: take over sockets created by systemd

[Friedrich, Eugen (ADITG/SW1)]

systemd provides a feature of socket-based activation, details in [1]
This commit adds an implementation to check if sockets were provided by
systemd and adds this as an additional socket to wayland display.
before adding sockets are checked for the correctness:
only AF_UNIX of type SOCK_STREAM are accepted

This is usefull for early rendering use-cases where weston and
early-rendering-application can be started parallel.

[1] https://www.freedesktop.org/software/systemd/man/systemd.socket.html

Signed-off-by: Eugen Friedrich <efriedrich at de.adit-jv.com>
---
 configure.ac         |  5 ++++-
 src/systemd-notify.c | 27 +++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)
 mode change 100644 => 100755 src/systemd-notify.c

diff --git a/configure.ac b/configure.ac
index 9e8115a..447cf6b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -634,7 +634,10 @@ AC_ARG_ENABLE(systemd_notify,
               AS_HELP_STRING([--enable-systemd-notify],
                              [Enables systemd notifications to
                               notify systemd about weston state
-                              and update watchdog.]),,
+                              and update watchdog.
+                              Also sockets provided by systemd
+                              in case of socket-base activation
+                              are added to wayland display]),,
               enable_systemd_notify=no)
 AM_CONDITIONAL(SYSTEMD_NOTIFY_SUPPORT, test x$enable_systemd_notify = xyes)
 if test "x$enable_systemd_notify" = "xyes"; then
diff --git a/src/systemd-notify.c b/src/systemd-notify.c
old mode 100644
new mode 100755
index e61db0f..0be1f6f
--- a/src/systemd-notify.c
+++ b/src/systemd-notify.c
@@ -28,6 +28,7 @@
 #include <errno.h>
 #include <stdlib.h>
 #include <systemd/sd-daemon.h>
+#include <sys/socket.h>
 #include <wayland-server.h>
 #include "shared/helpers.h"
 #include "shared/zalloc.h"
@@ -79,6 +80,8 @@ module_init(struct weston_compositor *compositor,
 	struct wl_event_loop *loop;
 	long watchdog_time_conv;
 	struct systemd_notifier *notifier;
+	int fd;
+	int systemd_socket_fds = 0;
 
 	notifier = zalloc(sizeof *notifier);
 	if (notifier == NULL)
@@ -89,6 +92,30 @@ module_init(struct weston_compositor *compositor,
 	wl_signal_add(&compositor->destroy_signal,
 		      &notifier->compositor_destroy_listener);
 
+	/*take additional display sockets if provided by systemd*/
+	systemd_socket_fds = sd_listen_fds(1);
+
+	if (systemd_socket_fds > 0) {
+		int current_fd = 0;
+
+		for (;current_fd < systemd_socket_fds; current_fd++) {
+			fd = SD_LISTEN_FDS_START + current_fd;
+
+			if (sd_is_socket(fd, AF_UNIX, SOCK_STREAM,1) > 0) {
+				if (wl_display_add_socket_fd(compositor->wl_display, fd)) {
+					weston_log("wl_display_add_socket_fd failed\n");
+					return -1;
+				}
+			} else {
+				weston_log("invalid socket provided from systemd\n");
+				return -1;
+			}
+		}
+
+		weston_log("info: add %d socket(s) provided by systemd\n",
+				current_fd);
+	}
+
 	sd_notify(0, "READY=1");
 
 	/* 'WATCHDOG_USEC' is environment variable that is set
-- 
2.4.11