From 29c28637505dcdf725085815e91185926a16239b Mon Sep 17 00:00:00 2001
From: pogokeen <pogokeen@1a8010ca-5511-0410-912e-c29ae57300e0>
Date: Thu, 28 Jun 2018 02:00:42 +0000
Subject: [PATCH] sdlayer.cpp: fix software renderer crash affecting Mapster32
 due to improper handling of lockcount in
 videoBeginDrawing()/videoEndDrawing() when using glsurface

git-svn-id: https://svn.eduke32.com/eduke32@6933 1a8010ca-5511-0410-912e-c29ae57300e0
---
 source/build/src/sdlayer.cpp | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/source/build/src/sdlayer.cpp b/source/build/src/sdlayer.cpp
index c327884ae..fd7acc90d 100644
--- a/source/build/src/sdlayer.cpp
+++ b/source/build/src/sdlayer.cpp
@@ -1733,10 +1733,15 @@ void videoBeginDrawing(void)
         modechange = 0;
         return;
     }
-    else if (!nogl)
-    {
-        if (offscreenrendering) return;
 
+    // lock the frame
+    if (lockcount++ > 0)
+        return;
+
+    if (offscreenrendering) return;
+
+    if (!nogl)
+    {
         frameplace = (intptr_t)glsurface_getBuffer();
         if (modechange)
         {
@@ -1747,12 +1752,6 @@ void videoBeginDrawing(void)
         return;
     }
 
-    // lock the frame
-    if (lockcount++ > 0)
-        return;
-
-    if (offscreenrendering) return;
-
     if (SDL_MUSTLOCK(sdl_buffersurface)) SDL_LockSurface(sdl_buffersurface);
     frameplace = (intptr_t)sdl_buffersurface->pixels;
 
@@ -1772,7 +1771,7 @@ void videoBeginDrawing(void)
 //
 void videoEndDrawing(void)
 {
-    if (bpp > 8 || !nogl)
+    if (bpp > 8)
     {
         if (!offscreenrendering) frameplace = 0;
         return;
@@ -1784,7 +1783,7 @@ void videoEndDrawing(void)
     if (lockcount == 0) return;
     lockcount = 0;
 
-    if (offscreenrendering) return;
+    if (offscreenrendering || !nogl) return;
 
     if (SDL_MUSTLOCK(sdl_buffersurface)) SDL_UnlockSurface(sdl_buffersurface);
 }