From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001

From: Christophe Fergeau <cfergeau@redhat.com>

Date: Fri, 20 Jul 2018 11:44:51 +0200

Subject: [PATCH] dcc: Fix QUIC fallback in get_compression_for_bitmap()

There was a small regression introduced in get_compression_for_bitmap()

by f401eb07f dcc: Rewrite dcc_image_compress.

If SPICE_IMAGE_COMPRESSION_AUTO_GLZ is specified, and the bitmap has a

stride which is bigger than its width (ie it has padding), then

get_compression_for_bitmap() will return SPICE_IMAGE_COMPRESSION_OFF

while in that case, we used to use QUIC for compression.

This happens because that function in the AUTO_GLZ case first checks if

QUIC should be used, if not, it decides to use GLZ, but then decides it

can't because of the stride, so falls back to OFF, while it used to

fall back to QUIC.

This commit only slightly reworks a preexisting if (!can_lz_compress())

check so that it's unconditional rather than depending on the previous

checks having been unsuccessful.

This issue could be observed by using a spice-html5 without support for

uncompressed bitmaps with end-of-line padding by simply starting a f28

VM and connecting to it/moving the mouse cursor in it.

Signed-off-by: Christophe Fergeau <cfergeau@redhat.com>

Acked-by: Frediano Ziglio <fziglio@redhat.com>

---

 server/dcc.c | 6 ++++--

 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/server/dcc.c b/server/dcc.c

index 3bf75a7..b632905 100644

--- a/server/dcc.c

+++ b/server/dcc.c

@@ -806,8 +806,10 @@ static SpiceImageCompression get_compression_for_bitmap(SpiceBitmap *bitmap,

                     bitmap_get_graduality_level(bitmap) == BITMAP_GRADUAL_HIGH) {

                     return SPICE_IMAGE_COMPRESSION_QUIC;

                 }

-            } else if (!can_lz_compress(bitmap) ||

-                       drawable->copy_bitmap_graduality == BITMAP_GRADUAL_HIGH) {

+            } else if (drawable->copy_bitmap_graduality == BITMAP_GRADUAL_HIGH) {

+                return SPICE_IMAGE_COMPRESSION_QUIC;

+            }

+            if (!can_lz_compress(bitmap)) {

                 return SPICE_IMAGE_COMPRESSION_QUIC;

             }

         }