0008-Fail-safe-when-displaying-colors.patch

From 938d64572b0667775ea70b94c9bb02ff81b1fda2 Mon Sep 17 00:00:00 2001
From: Demi Marie Obenour <demi@invisiblethingslab.com>
Date: Mon, 14 Jun 2021 00:28:03 -0400
Subject: [PATCH 8/9] Fail-safe when displaying colors

If something goes wrong, display a window as red.
---
 src/client.c  | 86 +++++++++++++++++++++++++--------------------------
 src/display.c |  4 ++-
 src/display.h |  2 ++
 3 files changed, 48 insertions(+), 44 deletions(-)

diff --git a/src/client.c b/src/client.c
index aa66f00..8510a2c 100644
--- a/src/client.c
+++ b/src/client.c
@@ -172,55 +172,55 @@ getQubesLabel (Client *c)
 {
     ScreenInfo *screen_info;
     DisplayInfo *display_info;
-    Atom atom_label;
-    Atom atom_label_color;
 
     screen_info = c->screen_info;
     display_info = screen_info->display_info;
 
-    atom_label = XInternAtom(display_info->dpy, "_QUBES_LABEL", TRUE);
-    atom_label_color = XInternAtom(display_info->dpy, "_QUBES_LABEL_COLOR", TRUE);
-
     c->qubes_label_color = QUBES_LABEL_DOM0;
-    if (atom_label_color) {
-        Atom actual_type;
-        int actual_format;
-        unsigned long nitems = 0, bytes_left;
-        unsigned char *data = 0;
-
-        if ((XGetWindowProperty (display_info->dpy, c->window, atom_label_color, 0L, 1L,
-                        FALSE, XA_CARDINAL, &actual_type, &actual_format, &nitems,
-                        &bytes_left, &data) == Success))
-        {
-            if (nitems == 1 && actual_format == 32) {
-                c->qubes_label_color = *(long*)data;
-            }
-        }
-    }
-    if (c->qubes_label_color == QUBES_LABEL_DOM0 && atom_label) {
-        Atom actual_type;
-        int actual_format;
-        unsigned long nitems = 0, bytes_left;
-        char *data = 0;
-
-        if ((XGetWindowProperty (display_info->dpy, c->window, atom_label, 0L, 1L,
-                        FALSE, AnyPropertyType, &actual_type, &actual_format, &nitems,
-                        &bytes_left, (unsigned char **) &data) == Success))
-        {
-            if (nitems != 1) {
-                // ERROR? Only Dom0 Windows don't have this property set...
-                c->qubes_label_color = QUBES_LABEL_DOM0;
-            } else {
-                int qubes_label = (int)*data;
-                if (qubes_label >= 0 && qubes_label < MAX_QUBES_LABELS) {
-                    c->qubes_label_color = qubes_label_colors[qubes_label];
-                } else {
-                    /* out of range?! */
-                    c->qubes_label_color = QUBES_LABEL_RED;
-                }
-            }
+    Atom actual_type;
+    int actual_format = 100;
+    unsigned long nitems = 0, bytes_left = 100;
+    unsigned char *data = 0;
+
+    if ((XGetWindowProperty (display_info->dpy, c->window,
+                    display_info->atoms[QUBES_LABEL_COLOR], 0L, 1L,
+                    FALSE, XA_CARDINAL, &actual_type, &actual_format,
+                    &nitems, &bytes_left, &data) != Success)) {
+        g_warning("Cannot check if a window is a Qubes window");
+        c->qubes_label_color = QUBES_LABEL_RED;
+        return;
+    } else if (nitems == 1 && actual_format == 32 && bytes_left == 0 && data) {
+        c->qubes_label_color = *(long*)data;
+        XFree(data);
+        return;
+    } else if (nitems || actual_format || bytes_left || data) {
+        XFree(data);
+        g_warning("Cannot check if a window is a Qubes window");
+        c->qubes_label_color = QUBES_LABEL_RED;
+        return;
+    } else if ((XGetWindowProperty (display_info->dpy, c->window,
+                    display_info->atoms[QUBES_LABEL], 0L, 1L,
+                    FALSE, AnyPropertyType, &actual_type, &actual_format,
+                    &nitems, &bytes_left, (unsigned char **) &data) != Success)) {
+        g_warning("Cannot get QUBES_LABEL");
+        c->qubes_label_color = QUBES_LABEL_RED;
+    } else if (!actual_type && !actual_format && !nitems && !bytes_left && !data) {
+        // Only Dom0 Windows don't have this property set...
+        c->qubes_label_color = QUBES_LABEL_DOM0;
+    } else if (nitems != 1 || bytes_left || !data || actual_type != XA_CARDINAL ||
+               actual_format != 8) {
+        XFree(data);
+        g_warning("Bogus QUBES_LABEL?");
+        c->qubes_label_color = QUBES_LABEL_RED;
+    } else {
+        int qubes_label = (int)*data;
+        XFree(data);
+        if (qubes_label >= 0 && qubes_label < MAX_QUBES_LABELS) {
+            c->qubes_label_color = qubes_label_colors[qubes_label];
         } else {
-            c->qubes_label_color = QUBES_LABEL_DOM0;
+            /* out of range?! */
+            g_warning("Out of range QUBES_LABEL?");
+            c->qubes_label_color = QUBES_LABEL_RED;
         }
     }
 }
diff --git a/src/display.c b/src/display.c
index d9cca8e..f9f35cb 100644
--- a/src/display.c
+++ b/src/display.c
@@ -179,7 +179,9 @@ myDisplayInitAtoms (DisplayInfo *display_info)
         "XFWM4_TIMESTAMP_PROP",
         "_XROOTPMAP_ID",
         "_XSETROOT_ID",
-        "_GTK_READ_RCFILES"
+        "_GTK_READ_RCFILES",
+        "_QUBES_LABEL",
+        "_QUBES_LABEL_COLOR",
     };
 
     g_assert (ATOM_COUNT == G_N_ELEMENTS (atom_names));
diff --git a/src/display.h b/src/display.h
index 1d6ffe6..c872a23 100644
--- a/src/display.h
+++ b/src/display.h
@@ -272,6 +272,8 @@ enum
     XROOTPMAP,
     XSETROOT,
     GTK_READ_RCFILES,
+    QUBES_LABEL,
+    QUBES_LABEL_COLOR,
     ATOM_COUNT
 };
 
-- 
2.31.1