From ce2bcc0a4f5aa9c728d0329ea0618c005c255d30 Mon Sep 17 00:00:00 2001
From: "Enrico Weigelt, metux IT consult" <info@metux.net>
Date: Thu, 3 Jul 2025 14:51:11 +0200
Subject: [PATCH] miext: damage: tolerate NULL pointers in DamageScreenFuncsRec

For now that case doensn't practically happen yet - all fields are at
least assigned to some default/dummy function. But in the future, we
might wanna get rid of dummies.

From now on, video drivers are allowed to assign them to NULL, if they
don't wanna have the default implementations and nothing happening
at all instead (no more need for having their own empty dummies)

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
---
 miext/damage/damage.c | 14 ++++++++++----
 miext/damage/damage.h |  3 +++
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/miext/damage/damage.c b/miext/damage/damage.c
index 4d146efaf..f54621caf 100644
--- a/miext/damage/damage.c
+++ b/miext/damage/damage.c
@@ -1714,7 +1714,8 @@ DamageCreate(DamageReportFunc damageReport,
     pDamage->damageDestroy = damageDestroy;
     pDamage->pScreen = pScreen;
 
-    (*pScrPriv->funcs.Create) (pDamage);
+    if (pScrPriv->funcs.Create)
+        pScrPriv->funcs.Create (pDamage);
 
     return pDamage;
 }
@@ -1755,7 +1756,8 @@ DamageRegister(DrawablePtr pDrawable, DamagePtr pDamage)
         pDamage->isWindow = FALSE;
     pDamage->pDrawable = pDrawable;
     damageInsertDamage(getDrawableDamageRef(pDrawable), pDamage);
-    (*pScrPriv->funcs.Register) (pDrawable, pDamage);
+    if (pScrPriv->funcs.Register)
+        pScrPriv->funcs.Register (pDrawable, pDamage);
 }
 
 void
@@ -1774,7 +1776,8 @@ DamageUnregister(DamagePtr pDamage)
 
     damageScrPriv(pScreen);
 
-    (*pScrPriv->funcs.Unregister) (pDrawable, pDamage);
+    if (pScrPriv->funcs.Unregister)
+        pScrPriv->funcs.Unregister (pDrawable, pDamage);
 
     if (pDrawable->type == DRAWABLE_WINDOW) {
         WindowPtr pWindow = (WindowPtr) pDrawable;
@@ -1817,7 +1820,10 @@ DamageDestroy(DamagePtr pDamage)
 
     if (pDamage->damageDestroy)
         (*pDamage->damageDestroy) (pDamage, pDamage->closure);
-    (*pScrPriv->funcs.Destroy) (pDamage);
+
+    if (pScrPriv->funcs.Destroy)
+        pScrPriv->funcs.Destroy (pDamage);
+
     RegionUninit(&pDamage->damage);
     RegionUninit(&pDamage->pendingDamage);
     free(pDamage);
diff --git a/miext/damage/damage.h b/miext/damage/damage.h
index b3185c18f..cd8053890 100644
--- a/miext/damage/damage.h
+++ b/miext/damage/damage.h
@@ -54,6 +54,9 @@ typedef void (*DamageScreenDestroyFunc) (DamagePtr);
  * Drivers can inject themselves here, in order to get notified on
  * DamageCreate(), DamageRegister(), DamageUnregister(), DamageDestroy().
  *
+ * The fields may be assigned to NULL, if no action at all is wanted.
+ * (by default assigned to default implementations)
+ *
  * This should ONLY be touched by video drivers, nobody else.
  *
  * So far the only one using it is the proprietary NVidia driver.