DRI: Clip cliprects obtained from DRIGetDrawableInfo to screen dimensions.

This is to avoid issues with redirected windows which are located partly or
fully outside of a screen edge, resulting in unusual cliprects which the 3D
drivers generally can't handle. The symptoms in such cases would be incorrect
rendering or even crashes or hangs.

2 files changed, 43 insertions, 10 deletions

diff --git a/hw/xfree86/dri/dri.c b/hw/xfree86/dri/dri.c
index d153c090b..dbc1690f0 100644
--- a/hw/xfree86/dri/dri.c
+++ b/hw/xfree86/dri/dri.c
@@ -1518,13 +1518,18 @@ DRIGetDrawableInfo(ScreenPtr pScreen,
 	       if (x1 > pScreen->width) x1 = pScreen->width;
 	       if (y1 > pScreen->height) y1 = pScreen->height;
 
-	       pDRIPriv->private_buffer_rect.x1 = x0;
-	       pDRIPriv->private_buffer_rect.y1 = y0;
-	       pDRIPriv->private_buffer_rect.x2 = x1;
-	       pDRIPriv->private_buffer_rect.y2 = y1;
-
-	       *numBackClipRects = 1;
-	       *pBackClipRects = &(pDRIPriv->private_buffer_rect);
+	       if (y0 >= y1 || x0 >= x1) {
+		    *numBackClipRects = 0;
+		    *pBackClipRects = NULL;
+	       } else {
+		    pDRIPriv->private_buffer_rect.x1 = x0;
+		    pDRIPriv->private_buffer_rect.y1 = y0;
+		    pDRIPriv->private_buffer_rect.x2 = x1;
+		    pDRIPriv->private_buffer_rect.y2 = y1;
+
+		    *numBackClipRects = 1;
+		    *pBackClipRects = &(pDRIPriv->private_buffer_rect);
+	       }
 	    } else {
 	       /* Use the frontbuffer cliprects for back buffers.  */
 	       *numBackClipRects = 0;
diff --git a/hw/xfree86/dri/xf86dri.c b/hw/xfree86/dri/xf86dri.c
index 933cd3e18..9690e8895 100644
--- a/hw/xfree86/dri/xf86dri.c
+++ b/hw/xfree86/dri/xf86dri.c
@@ -452,7 +452,7 @@ ProcXF86DRIGetDrawableInfo(
     xXF86DRIGetDrawableInfoReply	rep;
     DrawablePtr pDrawable;
     int X, Y, W, H;
-    drm_clip_rect_t * pClipRects;
+    drm_clip_rect_t * pClipRects, *pClippedRects;
     drm_clip_rect_t * pBackClipRects;
     int backX, backY, rc;
 
@@ -502,8 +502,35 @@ ProcXF86DRIGetDrawableInfo(
     if (rep.numBackClipRects) 
        rep.length += sizeof(drm_clip_rect_t) * rep.numBackClipRects;    
 
-    if (rep.numClipRects) 
+    pClippedRects = pClipRects;
+
+    if (rep.numClipRects) {
+       /* Clip cliprects to screen dimensions (redirected windows) */
+       pClippedRects = xalloc(rep.numClipRects * sizeof(drm_clip_rect_t));
+
+       if (pClippedRects) {
+	    ScreenPtr pScreen = screenInfo.screens[stuff->screen];
+	    int i, j;
+
+	    for (i = 0, j = 0; i < rep.numClipRects; i++) {
+		pClippedRects[j].x1 = max(pClipRects[i].x1, 0);
+		pClippedRects[j].y1 = max(pClipRects[i].y1, 0);
+		pClippedRects[j].x2 = min(pClipRects[i].x2, pScreen->width);
+		pClippedRects[j].y2 = min(pClipRects[i].y2, pScreen->height);
+
+		if (pClippedRects[j].x1 < pClippedRects[j].x2 &&
+		    pClippedRects[j].y1 < pClippedRects[j].y2) {
+		    j++;
+		}
+	    }
+
+	    rep.numClipRects = j;
+       } else {
+	    rep.numClipRects = 0;
+       }
+
        rep.length += sizeof(drm_clip_rect_t) * rep.numClipRects;
+    }
     
     rep.length = ((rep.length + 3) & ~3) >> 2;
 
@@ -512,7 +539,8 @@ ProcXF86DRIGetDrawableInfo(
     if (rep.numClipRects) {
 	WriteToClient(client,  
 		      sizeof(drm_clip_rect_t) * rep.numClipRects,
-		      (char *)pClipRects);
+		      (char *)pClippedRects);
+	xfree(pClippedRects);
     }
 
     if (rep.numBackClipRects) {