replace _NET_WM_PID with XResGetClientPid (#741)

window-props: use XResQueryClientIds to get pid

_NET_WM_PID is unreliable! It can be faked or pid might be from
different namespace. Ignore _NET_WM_PID and use XResQueryClientIds
to get pid.

https://gitlab.gnome.org/GNOME/metacity/-/commit/bcbe966511362a8eb8c8c64035ab160086c931f8

.build.yml

@@ -14,6 +14,7 @@ requires:
     - libcanberra
     - libgtop
     - libxpresent
+    - libxres
     - make
     - mate-common
     - mate-desktop
@@ -51,6 +52,7 @@ requires:
     - libxpresent-dev
     - libxrandr-dev
     - libxrender-dev
+    - libxres-dev
     - libxt-dev
     - make
     - mate-common
@@ -72,6 +74,7 @@ requires:
     - libSM-devel
     - libXdamage-devel
     - libXpresent-devel
+    - libXres-devel
     - libcanberra-devel
     - libgtop2-devel
     - libsoup-devel
@@ -110,6 +113,7 @@ requires:
     - libxpresent-dev
     - libxrandr-dev
     - libxrender-dev
+    - libxres-dev
     - libxt-dev
     - make
     - mate-common

configure.ac

@@ -164,7 +164,7 @@ if test x$have_xcomposite = xyes; then
 fi
 
 if test x$have_xcomposite = xyes; then
-  MARCO_PC_MODULES="$MARCO_PC_MODULES xcomposite >= $XCOMPOSITE_VERSION xfixes xrender xdamage"
+  MARCO_PC_MODULES="$MARCO_PC_MODULES xcomposite >= $XCOMPOSITE_VERSION xfixes xrender xdamage xres"
   AC_DEFINE(HAVE_COMPOSITE_EXTENSIONS, 1, [Building with compositing manager support])
   echo "Building with compositing manager"
 

meson.build

@@ -153,12 +153,14 @@ gtk_req = '>= 3.22.0'
 pango_req = '>= 1.2.0'
 libcanberra_gtk_req = '>= 3.22.0'
 startup_notification_req = '>= 0.7'
+xres_req = '>= 1.2.0'
 
 glib_dep = dependency('glib-2.0', version: glib_req)
 gtk_dep = dependency('gtk+-3.0', version: gtk_req)
 gio_dep = dependency('gio-2.0', version: gio_req)
 pango_dep = dependency('pango', version: pango_req)
 libcanberra_gtk_dep = dependency('libcanberra-gtk3')
+xres_dep = dependency('xres', version: xres_req)
 x11_dep = dependency('x11')
 
 marco_deps = [
@@ -167,6 +169,7 @@ marco_deps = [
   gio_dep,
   pango_dep,
   libcanberra_gtk_dep,
+  xres_dep,
 ]
 
 marco_message_deps = [

src/core/window-props.c

@@ -47,6 +47,7 @@
 #include "frame-private.h"
 #include "group.h"
 #include <X11/Xatom.h>
+#include <X11/extensions/XRes.h>
 #include <unistd.h>
 #include <string.h>
 #include <errno.h>
@@ -294,11 +295,56 @@ reload_wm_window_role (MetaWindow    *window,
   meta_window_update_role (window);
 }
 
+static pid_t
+get_local_pid (MetaWindow *window)
+{
+  pid_t pid;
+  XResClientIdSpec spec;
+  long num_ids;
+  XResClientIdValue *client_ids;
+  long i;
+
+  pid = -1;
+
+  spec.client = window->xwindow;
+  spec.mask = XRES_CLIENT_ID_PID_MASK;
+
+  XResQueryClientIds (window->display->xdisplay,
+                      1,
+                      &spec,
+                      &num_ids,
+                      &client_ids);
+
+  for (i = 0; i < num_ids; i++)
+    {
+      if (client_ids[i].spec.mask == XRES_CLIENT_ID_PID_MASK)
+        {
+          pid = XResGetClientPid (&client_ids[i]);
+          break;
+        }
+    }
+
+  XResClientIdsDestroy (num_ids, client_ids);
+
+  return pid;
+}
+
 static void
 reload_net_wm_pid (MetaWindow    *window,
                    MetaPropValue *value,
                    gboolean       initial)
 {
+  pid_t pid;
+
+  pid = get_local_pid (window);
+
+  if (pid != -1)
+    {
+      meta_verbose ("Using XResGetClientPid instead of _NET_WM_PID\n");
+
+      window->net_wm_pid = pid;
+      return;
+    }
   if (value->type != META_PROP_VALUE_INVALID)
     {
       gulong cardinal = (int) value->v.cardinal;