[mutter/wip/rstrode/rhel-8.0.0: 97/117] constraints: Enforce X11 size limits

[Ray Strode <halfline src gnome org>]

commit 7aed7293e38ef4e53e06f70748c78314ce03a2f4
Author: Florian Müllner <fmuellner gnome org>
Date:   Wed Mar 12 02:04:13 2014 +0100

    constraints: Enforce X11 size limits
    
    X11 limits windows to a maximum of 32767x32767, enforce that restriction
    to keep insanely huge windows from crashing the WM.

 src/core/constraints.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)
---
diff --git a/src/core/constraints.c b/src/core/constraints.c
index 8bfbe73ba..ca3bce9ea 100644
--- a/src/core/constraints.c
+++ b/src/core/constraints.c
@@ -106,6 +106,7 @@ typedef enum
   PRIORITY_TITLEBAR_VISIBLE = 4,
   PRIORITY_PARTIALLY_VISIBLE_ON_WORKAREA = 4,
   PRIORITY_CUSTOM_RULE = 4,
+  PRIORITY_XLIMITS = 4,
   PRIORITY_MAXIMUM = 4 /* Dummy value used for loop end = max(all priorities) */
 } ConstraintPriority;
 
@@ -196,6 +197,10 @@ static gboolean constrain_partially_onscreen (MetaWindow         *window,
                                               ConstraintInfo     *info,
                                               ConstraintPriority  priority,
                                               gboolean            check_only);
+static gboolean constrain_xlimits            (MetaWindow         *window,
+                                              ConstraintInfo     *info,
+                                              ConstraintPriority  priority,
+                                              gboolean            check_only);
 
 static void setup_constraint_info        (ConstraintInfo      *info,
                                           MetaWindow          *window,
@@ -231,6 +236,7 @@ static const Constraint all_constraints[] = {
   {constrain_fully_onscreen,     "constrain_fully_onscreen"},
   {constrain_titlebar_visible,   "constrain_titlebar_visible"},
   {constrain_partially_onscreen, "constrain_partially_onscreen"},
+  {constrain_xlimits,            "constrain_xlimits"},
   {NULL,                         NULL}
 };
 
@@ -1675,3 +1681,39 @@ constrain_partially_onscreen (MetaWindow         *window,
 
   return retval;
 }
+
+
+#define MAX_WINDOW_SIZE 32767
+
+static gboolean
+constrain_xlimits (MetaWindow         *window,
+                   ConstraintInfo     *info,
+                   ConstraintPriority  priority,
+                   gboolean            check_only)
+{
+  int max_w, max_h;
+  gboolean constraint_already_satisfied;
+
+  if (priority > PRIORITY_XLIMITS)
+    return TRUE;
+
+  max_w = max_h = MAX_WINDOW_SIZE;
+
+  if (window->frame)
+    {
+      MetaFrameBorders borders;
+      meta_frame_calc_borders (window->frame, &borders);
+
+      max_w -= (borders.total.left + borders.total.right);
+      max_h -= (borders.total.top + borders.total.bottom);
+    }
+
+  constraint_already_satisfied = info->current.width < max_w && info->current.height < max_h;
+  if (check_only || constraint_already_satisfied)
+    return constraint_already_satisfied;
+
+  info->current.width = MIN (info->current.width, max_w);
+  info->current.height = MIN (info->current.height, max_h);
+
+  return TRUE;
+}