[PATCH v2 1/2] vnc: fix VNC artifacts

[Cameron Esfahani]

Patch de3f7de7f4e257ce44cdabb90f5f17ee99624557 was too simplistic in its
implementation: it didn't account for the ZLIB z_stream mutating with
each compression.  Because of the mutation, simply resetting the output
buffer's offset wasn't sufficient to "rewind" the operation.  The mutated
z_stream would generate future zlib blocks which referred to symbols in
past blocks which weren't sent.  This would lead to artifacting.

This reverts commit de3f7de7f4e257ce44cdabb90f5f17ee99624557.

Fixes: <de3f7de7f4e257> ("vnc: allow fall back to RAW encoding")
Signed-off-by: Cameron Esfahani <address@hidden>
---
 ui/vnc.c | 20 ++------------------
 1 file changed, 2 insertions(+), 18 deletions(-)

diff --git a/ui/vnc.c b/ui/vnc.c
index 4100d6e404..3e8d1f1207 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -898,8 +898,6 @@ int vnc_raw_send_framebuffer_update(VncState *vs, int x, 
int y, int w, int h)
 int vnc_send_framebuffer_update(VncState *vs, int x, int y, int w, int h)
 {
     int n = 0;
-    bool encode_raw = false;
-    size_t saved_offs = vs->output.offset;
 
     switch(vs->vnc_encoding) {
         case VNC_ENCODING_ZLIB:
@@ -922,24 +920,10 @@ int vnc_send_framebuffer_update(VncState *vs, int x, int 
y, int w, int h)
             n = vnc_zywrle_send_framebuffer_update(vs, x, y, w, h);
             break;
         default:
-            encode_raw = true;
+            vnc_framebuffer_update(vs, x, y, w, h, VNC_ENCODING_RAW);
+            n = vnc_raw_send_framebuffer_update(vs, x, y, w, h);
             break;
     }
-
-    /* If the client has the same pixel format as our internal buffer and
-     * a RAW encoding would need less space fall back to RAW encoding to
-     * save bandwidth and processing power in the client. */
-    if (!encode_raw && vs->write_pixels == vnc_write_pixels_copy &&
-        12 + h * w * VNC_SERVER_FB_BYTES <= (vs->output.offset - saved_offs)) {
-        vs->output.offset = saved_offs;
-        encode_raw = true;
-    }
-
-    if (encode_raw) {
-        vnc_framebuffer_update(vs, x, y, w, h, VNC_ENCODING_RAW);
-        n = vnc_raw_send_framebuffer_update(vs, x, y, w, h);
-    }
-
     return n;
 }
 
-- 
2.24.0