Re: Segmentation fault in "Fake_glXUseXFont" (Mesa 10.4.3)

From d85e120250fe4678891384b3d9055f8b7f564318 Mon Sep 17 00:00:00 2001
From: Brian Paul <[email protected]>
Date: Wed, 25 Feb 2015 09:16:02 -0700
Subject: [PATCH] xlib: fix some broken GLX functions

Calling glXGetCurrentDisplay(), glXGetCurrentDrawable() or
glXGetCurrentReadDrawable() returned garbage.  This also caused
functions like glXUseXFont() to fail.

Get rid of the old __GLXContext type and plumb the above functions
down to corresponding XMesa functions.

Fixes issue reported by Martin Knoblauch on mesa-users list.

Cc: "10.5, 10.4" <[email protected]>
---
 src/mesa/drivers/x11/glxapi.c | 19 +++++++------------
 src/mesa/drivers/x11/glxapi.h | 14 --------------
 src/mesa/drivers/x11/xfonts.c |  3 ++-
 src/mesa/drivers/x11/xm_api.c | 37 +++++++++++++++++++++++++++++++++++++
 src/mesa/drivers/x11/xmesa.h  | 10 ++++++++++
 5 files changed, 56 insertions(+), 27 deletions(-)

diff --git a/src/mesa/drivers/x11/glxapi.c b/src/mesa/drivers/x11/glxapi.c
index a870e94..9399a5e 100644
--- a/src/mesa/drivers/x11/glxapi.c
+++ b/src/mesa/drivers/x11/glxapi.c
@@ -38,6 +38,7 @@
 #include "main/compiler.h"
 #include "glapi/glapi.h"
 #include "glxapi.h"
+#include "xmesa.h"
 
 
 extern struct _glxapi_table *_mesa_GetGLXDispatchTable(void);
@@ -229,9 +230,6 @@ glXGetConfig(Display *dpy, XVisualInfo *visinfo, int attrib, int *value)
 }
 
 
-/* declare here to avoid including xmesa.h */
-extern void *XMesaGetCurrentContext(void);
-
 GLXContext PUBLIC
 glXGetCurrentContext(void)
 {
@@ -242,8 +240,7 @@ glXGetCurrentContext(void)
 GLXDrawable PUBLIC
 glXGetCurrentDrawable(void)
 {
-   __GLXcontext *gc = (__GLXcontext *) glXGetCurrentContext();
-   return gc ? gc->currentDrawable : 0;
+   return XMesaGetCurrentDrawable();
 }
 
 
@@ -382,10 +379,7 @@ glXQueryServerString(Display *dpy, int screen, int name)
 Display PUBLIC *
 glXGetCurrentDisplay(void)
 {
-   /* Same code as in libGL's glxext.c */
-   __GLXcontext *gc = (__GLXcontext *) glXGetCurrentContext();
-   if (NULL == gc) return NULL;
-   return gc->currentDpy;
+   return XMesaGetCurrentDisplay();
 }
 
 
@@ -483,8 +477,7 @@ glXDestroyWindow(Display *dpy, GLXWindow window)
 GLXDrawable PUBLIC
 glXGetCurrentReadDrawable(void)
 {
-   __GLXcontext *gc = (__GLXcontext *) glXGetCurrentContext();
-   return gc ? gc->currentReadable : 0;
+   return XMesaGetCurrentReadDrawable();
 }
 
 
@@ -679,7 +672,9 @@ glXFreeContextEXT(Display *dpy, GLXContext context)
 GLXContextID PUBLIC
 glXGetContextIDEXT(const GLXContext context)
 {
-   return ((__GLXcontext *) context)->xid;
+   /* We have no XID for Mesa's fake GLX contexts */
+   fprintf(stderr, "Mesa: glXGetContextIDEXT not supported\n");
+   return 0;
 }
 
 Display PUBLIC *
diff --git a/src/mesa/drivers/x11/glxapi.h b/src/mesa/drivers/x11/glxapi.h
index bd6e970..a7622a8 100644
--- a/src/mesa/drivers/x11/glxapi.h
+++ b/src/mesa/drivers/x11/glxapi.h
@@ -31,20 +31,6 @@
 #include "GL/glx.h"
 
 
-/* The GLX API dispatcher (i.e. this code) is being built into stand-alone
- * Mesa.  We don't know anything about XFree86 or real GLX so we define a
- * minimal __GLXContextRec here so some of the functions in this file can
- * work properly.
- */
-typedef struct __GLXcontextRec {
-   Display *currentDpy;
-   GLboolean isDirect;
-   GLXDrawable currentDrawable;
-   GLXDrawable currentReadable;
-   XID xid;
-} __GLXcontext;
-
-
 /*
  * Almost all the GLX API functions get routed through this dispatch table.
  * The exceptions are the glXGetCurrentXXX() functions.
diff --git a/src/mesa/drivers/x11/xfonts.c b/src/mesa/drivers/x11/xfonts.c
index e9a38ba..f7a80f0 100644
--- a/src/mesa/drivers/x11/xfonts.c
+++ b/src/mesa/drivers/x11/xfonts.c
@@ -225,7 +225,8 @@ Fake_glXUseXFont(Font font, int first, int count, int listbase)
    dpy = glXGetCurrentDisplay();
    if (!dpy)
       return;			/* I guess glXMakeCurrent wasn't called */
-   win = RootWindow(dpy, DefaultScreen(dpy));
+   i = DefaultScreen(dpy);
+   win = RootWindow(dpy, i);
 
    fs = XQueryFont(dpy, font);
    if (!fs) {
diff --git a/src/mesa/drivers/x11/xm_api.c b/src/mesa/drivers/x11/xm_api.c
index 89c219e..f1bd8a8 100644
--- a/src/mesa/drivers/x11/xm_api.c
+++ b/src/mesa/drivers/x11/xm_api.c
@@ -1276,6 +1276,19 @@ XMesaContext XMesaGetCurrentContext( void )
 }
 
 
+Display *XMesaGetCurrentDisplay(void)
+{
+   GET_CURRENT_CONTEXT(ctx);
+   if (ctx) {
+      XMesaContext xmesa = XMESA_CONTEXT(ctx);
+      return xmesa->display;
+   }
+   else {
+      return NULL;
+   }
+}
+
+
 XMesaBuffer XMesaGetCurrentBuffer( void )
 {
    GET_CURRENT_CONTEXT(ctx);
@@ -1302,6 +1315,30 @@ XMesaBuffer XMesaGetCurrentReadBuffer( void )
 }
 
 
+GLXDrawable XMesaGetCurrentDrawable(void)
+{
+   XMesaBuffer xmbuffer = XMesaGetCurrentBuffer();
+   if (xmbuffer) {
+      struct xmesa_renderbuffer *front = xmbuffer->frontxrb;
+      if (front)
+         return front->drawable;
+   }
+   return 0;
+}
+
+
+GLXDrawable XMesaGetCurrentReadDrawable(void)
+{
+   XMesaBuffer xmbuffer = XMesaGetCurrentReadBuffer();
+   if (xmbuffer) {
+      struct xmesa_renderbuffer *front = xmbuffer->frontxrb;
+      if (front)
+         return front->drawable;
+   }
+   return 0;
+}
+
+
 
 GLboolean XMesaSetFXmode( GLint mode )
 {
diff --git a/src/mesa/drivers/x11/xmesa.h b/src/mesa/drivers/x11/xmesa.h
index b6a2576..ad81031 100644
--- a/src/mesa/drivers/x11/xmesa.h
+++ b/src/mesa/drivers/x11/xmesa.h
@@ -228,11 +228,21 @@ extern XMesaContext XMesaGetCurrentContext( void );
 
 
 /*
+ * Return Display * for currently bound context.
+ */
+extern Display *XMesaGetCurrentDisplay(void);
+
+
+/*
  * Return handle to the current (draw) buffer.
  */
 extern XMesaBuffer XMesaGetCurrentBuffer( void );
 
 
+extern GLXDrawable XMesaGetCurrentDrawable(void);
+extern GLXDrawable XMesaGetCurrentReadDrawable(void);
+
+
 /*
  * Return handle to the current read buffer.
  * New in Mesa 3.3
-- 
1.9.1