glx: fix error code when there is no context bound

v2: change all related NULL checks to check against dummyContext
v3: really check for dummyContext *only* when ctx was from
    __glXGetCurrentContext
v4: cover more checks, add dummyBuffer, dummyVtable (Emil)

Signed-off-by: Bernard Kilarski <bernard.r.kilarski@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Cc: "11.2" <mesa-stable@lists.freedesktop.org>

src/glx/glx_error.c

@@ -43,7 +43,7 @@ __glXSendError(Display * dpy, int_fast8_t errorCode, uint_fast32_t resourceID,
    xError error;
 
    assert(glx_dpy);
-   assert(gc);
+   assert(gc != &dummyContext);
 
    LockDisplay(dpy);
 

src/glx/glx_pbuffer.c

@@ -328,7 +328,7 @@ GetDrawableAttribute(Display * dpy, GLXDrawable drawable,
        *   the calling thread's current context a GLXBadDrawable error is
        *   generated."
        */
-      if (pdraw == NULL || gc == NULL || gc->currentDpy != dpy ||
+      if (pdraw == NULL || gc == &dummyContext || gc->currentDpy != dpy ||
          (gc->currentDrawable != drawable &&
          gc->currentReadable != drawable)) {
          __glXSendError(dpy, GLXBadDrawable, drawable,

src/glx/glxcmds.c

@@ -524,7 +524,7 @@ glXWaitGL(void)
 {
    struct glx_context *gc = __glXGetCurrentContext();
 
-   if (gc && gc->vtable->wait_gl)
+   if (gc != &dummyContext && gc->vtable->wait_gl)
       gc->vtable->wait_gl(gc);
 }
 
@@ -537,7 +537,7 @@ glXWaitX(void)
 {
    struct glx_context *gc = __glXGetCurrentContext();
 
-   if (gc && gc->vtable->wait_x)
+   if (gc != &dummyContext && gc->vtable->wait_x)
       gc->vtable->wait_x(gc);
 }
 
@@ -546,7 +546,7 @@ glXUseXFont(Font font, int first, int count, int listBase)
 {
    struct glx_context *gc = __glXGetCurrentContext();
 
-   if (gc && gc->vtable->use_x_font)
+   if (gc != &dummyContext && gc->vtable->use_x_font)
       gc->vtable->use_x_font(gc, font, first, count, listBase);
 }
 
@@ -838,7 +838,7 @@ glXSwapBuffers(Display * dpy, GLXDrawable drawable)
       __GLXDRIdrawable *pdraw = GetGLXDRIDrawable(dpy, drawable);
 
       if (pdraw != NULL) {
-         Bool flush = gc && drawable == gc->currentDrawable;
+         Bool flush = gc != &dummyContext && drawable == gc->currentDrawable;
 
          (*pdraw->psc->driScreen->swapBuffers)(pdraw, 0, 0, 0, flush);
          return;
@@ -855,7 +855,7 @@ glXSwapBuffers(Display * dpy, GLXDrawable drawable)
     ** The calling thread may or may not have a current context.  If it
     ** does, send the context tag so the server can do a flush.
     */
-   if ((gc != NULL) && (dpy == gc->currentDpy) &&
+   if ((gc != &dummyContext) && (dpy == gc->currentDpy) &&
        ((drawable == gc->currentDrawable)
         || (drawable == gc->currentReadable))) {
       tag = gc->currentContextTag;
@@ -1388,7 +1388,7 @@ _GLX_PUBLIC Display *
 glXGetCurrentDisplay(void)
 {
    struct glx_context *gc = __glXGetCurrentContext();
-   if (NULL == gc)
+   if (gc == &dummyContext)
       return NULL;
    return gc->currentDpy;
 }
@@ -1751,7 +1751,7 @@ __glXSwapIntervalSGI(int interval)
    CARD32 *interval_ptr;
    CARD8 opcode;
 
-   if (gc == NULL) {
+   if (gc == &dummyContext) {
       return GLX_BAD_CONTEXT;
    }
 
@@ -1805,7 +1805,7 @@ __glXSwapIntervalMESA(unsigned int interval)
 #ifdef GLX_DIRECT_RENDERING
    struct glx_context *gc = __glXGetCurrentContext();
 
-   if (gc != NULL && gc->isDirect) {
+   if (gc != &dummyContext && gc->isDirect) {
       struct glx_screen *psc;
 
       psc = GetGLXScreenConfigs( gc->currentDpy, gc->screen);
@@ -1827,7 +1827,7 @@ __glXGetSwapIntervalMESA(void)
 #ifdef GLX_DIRECT_RENDERING
    struct glx_context *gc = __glXGetCurrentContext();
 
-   if (gc != NULL && gc->isDirect) {
+   if (gc != &dummyContext && gc->isDirect) {
       struct glx_screen *psc;
 
       psc = GetGLXScreenConfigs( gc->currentDpy, gc->screen);
@@ -1857,7 +1857,7 @@ __glXGetVideoSyncSGI(unsigned int *count)
    __GLXDRIdrawable *pdraw;
 #endif
 
-   if (!gc)
+   if (gc == &dummyContext)
       return GLX_BAD_CONTEXT;
 
 #ifdef GLX_DIRECT_RENDERING
@@ -1899,7 +1899,7 @@ __glXWaitVideoSyncSGI(int divisor, int remainder, unsigned int *count)
    if (divisor <= 0 || remainder < 0)
       return GLX_BAD_VALUE;
 
-   if (!gc)
+   if (gc == &dummyContext)
       return GLX_BAD_CONTEXT;
 
 #ifdef GLX_DIRECT_RENDERING
@@ -2212,7 +2212,7 @@ __glXSwapBuffersMscOML(Display * dpy, GLXDrawable drawable,
    struct glx_screen *psc = pdraw ? pdraw->psc : NULL;
 #endif
 
-   if (!gc) /* no GLX for this */
+   if (gc == &dummyContext) /* no GLX for this */
       return -1;
 
 #ifdef GLX_DIRECT_RENDERING
@@ -2392,7 +2392,7 @@ __glXCopySubBufferMESA(Display * dpy, GLXDrawable drawable,
     ** does, send the context tag so the server can do a flush.
     */
    gc = __glXGetCurrentContext();
-   if ((gc != NULL) && (dpy == gc->currentDpy) &&
+   if ((gc != &dummyContext) && (dpy == gc->currentDpy) &&
        ((drawable == gc->currentDrawable) ||
         (drawable == gc->currentReadable))) {
       tag = gc->currentContextTag;
@@ -2431,7 +2431,7 @@ __glXBindTexImageEXT(Display * dpy,
 {
    struct glx_context *gc = __glXGetCurrentContext();
 
-   if (gc == NULL || gc->vtable->bind_tex_image == NULL)
+   if (gc == &dummyContext || gc->vtable->bind_tex_image == NULL)
       return;
 
    gc->vtable->bind_tex_image(dpy, drawable, buffer, attrib_list);
@@ -2442,7 +2442,7 @@ __glXReleaseTexImageEXT(Display * dpy, GLXDrawable drawable, int buffer)
 {
    struct glx_context *gc = __glXGetCurrentContext();
 
-   if (gc == NULL || gc->vtable->release_tex_image == NULL)
+   if (gc == &dummyContext || gc->vtable->release_tex_image == NULL)
       return;
 
    gc->vtable->release_tex_image(dpy, drawable, buffer);

src/glx/query_renderer.c

@@ -106,7 +106,7 @@ glXQueryCurrentRendererIntegerMESA(int attribute, unsigned int *value)
 {
    struct glx_context *gc = __glXGetCurrentContext();
 
-   if (gc == NULL)
+   if (gc == &dummyContext)
       return False;
 
    return __glXQueryRendererInteger(gc->psc, attribute, value);
@@ -166,7 +166,7 @@ glXQueryCurrentRendererStringMESA(int attribute)
 {
    struct glx_context *gc = __glXGetCurrentContext();
 
-   if (gc == NULL)
+   if (gc == &dummyContext)
       return False;
 
    return __glXQueryRendererString(gc->psc, attribute);

src/glx/tests/fake_glx_screen.cpp

@@ -75,7 +75,20 @@ indirect_create_context_attribs(struct glx_screen *base,
    return indirect_create_context(base, config_base, shareList, 0);
 }
 
-__thread void *__glX_tls_Context = NULL;
+/* This is necessary so that we don't have to link with glxcurrent.c
+ * which would require us to link with X libraries and what not.
+ */
+GLubyte dummyBuffer[__GLX_BUFFER_LIMIT_SIZE];
+struct glx_context_vtable dummyVtable;
+struct glx_context dummyContext = {
+   &dummyBuffer[0],
+   &dummyBuffer[0],
+   &dummyBuffer[0],
+   &dummyBuffer[__GLX_BUFFER_LIMIT_SIZE],
+   sizeof(dummyBuffer),
+   &dummyVtable
+};
+__thread void *__glX_tls_Context = &dummyContext;
 
 #if !defined(GLX_USE_TLS)
 extern "C" struct glx_context *