X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=src%2Flogin%2Flogind-session.c;h=65bbb77750b27ffdb1d575b02d3ce3c78c6c7ff8;hb=492d7a3038b154e1813a1ece913a5a27148fec19;hp=eeb58c9031b71d1bce41805cb778e6d4c7890d30;hpb=d5099efc47d4e6ac60816b5381a5f607ab03f06e;p=elogind.git

diff --git a/src/login/logind-session.c b/src/login/logind-session.c
index eeb58c903..65bbb7775 100644
--- a/src/login/logind-session.c
+++ b/src/login/logind-session.c
@@ -1053,6 +1053,31 @@ void session_restore_vt(Session *s) {
         s->vtfd = safe_close(s->vtfd);
 }
 
+void session_leave_vt(Session *s) {
+        int r;
+
+        assert(s);
+
+        /* This is called whenever we get a VT-switch signal from the kernel.
+         * We acknowledge all of them unconditionally. Note that session are
+         * free to overwrite those handlers and we only register them for
+         * sessions with controllers. Legacy sessions are not affected.
+         * However, if we switch from a non-legacy to a legacy session, we must
+         * make sure to pause all device before acknowledging the switch. We
+         * process the real switch only after we are notified via sysfs, so the
+         * legacy session might have already started using the devices. If we
+         * don't pause the devices before the switch, we might confuse the
+         * session we switch to. */
+
+        if (s->vtfd < 0)
+                return;
+
+        session_device_pause_all(s);
+        r = ioctl(s->vtfd, VT_RELDISP, 1);
+        if (r < 0)
+                log_debug("Cannot release VT of session %s: %m", s->id);
+}
+
 bool session_is_controller(Session *s, const char *sender) {
         assert(s);