From 07694559cc0c65ce1cca9ac33b165cef84c34d5e Mon Sep 17 00:00:00 2001
From: Ryan Gonzalez <ryan.gonzalez@collabora.com>
Date: Fri, 7 Jan 2022 17:14:43 -0600
Subject: xutils: Get the correct PID for clients inside PID namespaces

This tries to use XResQueryClientIds to fetch the client's PID, which
will return the PID as seen by the host, rather than the PID as seen by
the client.

Signed-off-by: Ryan Gonzalez <ryan.gonzalez@collabora.com>
---
 libwnck/xutils.c | 36 +++++++++++++++++++++++++++++++++---
 1 file changed, 33 insertions(+), 3 deletions(-)

diff --git a/libwnck/xutils.c b/libwnck/xutils.c
index e95abef..9d0ee20 100644
--- a/libwnck/xutils.c
+++ b/libwnck/xutils.c
@@ -27,6 +27,9 @@
 #if HAVE_CAIRO_XLIB_XRENDER
 #include <cairo-xlib-xrender.h>
 #endif
+#ifdef HAVE_XRES
+#include <X11/extensions/XRes.h>
+#endif
 #include "screen.h"
 #include "window.h"
 #include "private.h"
@@ -1146,14 +1149,41 @@ int
 _wnck_get_pid (Screen *screen,
                Window  xwindow)
 {
-  int val;
+  int pid = -1;
+
+#ifdef HAVE_XRES
+  XResClientIdSpec client_spec;
+  long client_id_count = 0;
+  XResClientIdValue *client_ids = NULL;
+
+  client_spec.client = xwindow;
+  client_spec.mask = XRES_CLIENT_ID_PID_MASK;
+
+  if (XResQueryClientIds (DisplayOfScreen (screen), 1, &client_spec,
+                          &client_id_count, &client_ids) == Success)
+    {
+      long i;
+
+      for (i = 0; i < client_id_count; i++)
+        {
+          pid = XResGetClientPid (&client_ids[i]);
+          if (pid != -1)
+            break;
+        }
+
+      XResClientIdsDestroy (client_id_count, client_ids);
+
+      if (pid != -1)
+        return pid;
+    }
+#endif
 
   if (!_wnck_get_cardinal (screen, xwindow,
                            _wnck_atom_get ("_NET_WM_PID"),
-                           &val))
+                           &pid))
     return 0;
   else
-    return val;
+    return pid;
 }
 
 char*
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