[PATCH xserver 2/2] randr: Use RRCrtcGetScanoutSize() in ProcRRSetScreenSize()

[Alex Goins]

Previously, ProcRRSetScreenSize() manually computed the dimensions of a CRTC's
viewport in order to check that it does not extend beyond the bounds of the new
screen size. It did this incorrectly, leading to bugs.

A previous patch "randr: Fix rotation check in ProcRRSetScreenSize()" fixed the
issue by directly correcting the calculation, but to avoid future bugs of this
class, this patch uses RRCrtcGetScanoutSize() to do the calculation, implicitly
accounting for all possible transforms.

There is existing precedent for this method in ProcRRSetCrtcConfig(), where
RRModeGetScanoutSize() is used directly due to the transform having not yet been
applied but the check is otherwise the same.

Signed-off-by: Alex Goins <agoins at nvidia.com>
---
 randr/rrscreen.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/randr/rrscreen.c b/randr/rrscreen.c
index f484383..7321eef 100644
--- a/randr/rrscreen.c
+++ b/randr/rrscreen.c
@@ -265,17 +265,12 @@ ProcRRSetScreenSize(ClientPtr client)
     }
     for (i = 0; i < pScrPriv->numCrtcs; i++) {
         RRCrtcPtr crtc = pScrPriv->crtcs[i];
-        RRModePtr mode = crtc->mode;
 
-        if (mode) {
-            int source_width = mode->mode.width;
-            int source_height = mode->mode.height;
-            Rotation rotation = crtc->rotation;
+        if (crtc->mode) {
+            int source_width;
+            int source_height;
 
-            if (rotation & (RR_Rotate_90 | RR_Rotate_270)) {
-                source_width = mode->mode.height;
-                source_height = mode->mode.width;
-            }
+            RRCrtcGetScanoutSize(crtc, &source_width, &source_height);
 
             if (crtc->x + source_width > stuff->width ||
                 crtc->y + source_height > stuff->height)
-- 
2.7.4