From 297003126d44d8a31bb6c3899817f8f2dff29b80 Mon Sep 17 00:00:00 2001
From: Uli Schlachter <psychon@znc.in>
Date: Fri, 10 Aug 2018 16:39:46 +0200
Subject: [PATCH] Handle unsetting of .transient_for

When a window has a WM_TRANSIENT_FOR property that is later unset,
awesome would still keep c.transient_for pointing to the previous
"parent client". This commit fixes that.

First, property_update_wm_transient_for() is fixed so that it unsets
c->transient_for_window if the WM_TRANSIENT_FOR property is deleted.
Additionally, this then calls client_find_transient_for() to update the
c->transient_for pointer.

Secondly (and a bit unrelated), this changes client_find_transient_for()
so that it always sets c->transient_for. Previously, if updating this
property would introduce a cycle in the transient_for relation, it would
just leave c->transient_for with its old value. After this change, it
gets explicitly set to NULL instead.

Signed-off-by: Uli Schlachter <psychon@znc.in>
---
 objects/client.c | 16 ++++++++++------
 property.c       | 10 +++++++---
 2 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/objects/client.c b/objects/client.c
index 817205638..197054878 100644
--- a/objects/client.c
+++ b/objects/client.c
@@ -983,7 +983,9 @@ client_find_transient_for(client_t *c)
 {
     int counter;
     client_t *tc, *tmp;
+    lua_State *L = globalconf_get_lua_State();
 
+    /* This might return NULL, in which case we unset transient_for */
     tmp = tc = client_getbywin(c->transient_for_window);
 
     /* Verify that there are no loops in the transient_for relation after we are done */
@@ -994,14 +996,16 @@ client_find_transient_for(client_t *c)
             counter = globalconf.stack.len+1;
         tmp = tmp->transient_for;
     }
-    if (counter <= globalconf.stack.len)
-    {
-        lua_State *L = globalconf_get_lua_State();
 
-        luaA_object_push(L, c);
-        client_set_transient_for(L, -1, tc);
-        lua_pop(L, 1);
+    if (counter > globalconf.stack.len)
+    {
+        /* There was a loop, so unset .transient_for */
+        tc = NULL;
     }
+
+    luaA_object_push(L, c);
+    client_set_transient_for(L, -1, tc);
+    lua_pop(L, 1);
 }
 
 void
diff --git a/property.c b/property.c
index b5c5de145..8ee102a3a 100644
--- a/property.c
+++ b/property.c
@@ -107,9 +107,13 @@ property_update_wm_transient_for(client_t *c, xcb_get_property_cookie_t cookie)
     xcb_window_t trans;
 
     if(!xcb_icccm_get_wm_transient_for_reply(globalconf.connection,
-					     cookie,
-					     &trans, NULL))
-            return;
+                                             cookie,
+                                             &trans, NULL))
+    {
+        c->transient_for_window = XCB_NONE;
+        client_find_transient_for(c);
+        return;
+    }
 
     c->transient_for_window = trans;