Generate the GLX extension list for swrast in the same way as dri and dri2 do.

Rather than using a fixed list of GLX extensions for swrast, generate the
extension list in the same way as dri and dri2 do.

This still looks a bit wonky: swrast and DRI1 will still always report certain
GLX extensions, as __glXInitExtensionEnableBits() has enabled them, even though
they then subsequently check if the underlying driver supports them (e.g.
GLX_SGI_make_current_read)

This has a couple of side-effects on the reported GLX extensions for swrast:
- GLX_SGIS_multisample is now reported on APPLE (I can't work out why this
conditional was added, it dates back to the XFree86 4.4RC3 import)
- GLX_SGIX_visual_select_group is now reported (this is probably pointless but
benign)

Signed-off-by: Jon TURNEY <jon.turney@dronecode.org.uk>

2 files changed, 36 insertions, 14 deletions

diff --git a/glx/glxdriswrast.c b/glx/glxdriswrast.c
index b47839868..7eb537df4 100644
--- a/glx/glxdriswrast.c
+++ b/glx/glxdriswrast.c
@@ -75,6 +75,8 @@ struct __GLXDRIscreen {
     const __DRIcopySubBufferExtension *copySubBuffer;
     const __DRItexBufferExtension *texBuffer;
     const __DRIconfig **driConfigs;
+
+    unsigned char glx_enable_bits[__GLX_EXT_BYTES];
 };
 
 struct __GLXDRIcontext {
@@ -410,12 +412,27 @@ initializeExtensions(__GLXDRIscreen * screen)
 
     extensions = screen->core->getExtensions(screen->driScreen);
 
+    /* GLX_MESA_copy_sub_buffer is always enabled. */
+    __glXEnableExtension(screen->glx_enable_bits, "GLX_MESA_copy_sub_buffer");
+
     for (i = 0; extensions[i]; i++) {
+#ifdef __DRI_READ_DRAWABLE
+        if (strcmp(extensions[i]->name, __DRI_READ_DRAWABLE) == 0) {
+            __glXEnableExtension(screen->glx_enable_bits,
+                                 "GLX_SGI_make_current_read");
+
+            LogMessage(X_INFO, "AIGLX: enabled GLX_SGI_make_current_read\n");
+        }
+#endif
+
 #ifdef __DRI_COPY_SUB_BUFFER
         if (strcmp(extensions[i]->name, __DRI_COPY_SUB_BUFFER) == 0) {
             screen->copySubBuffer =
                 (const __DRIcopySubBufferExtension *) extensions[i];
-            /* GLX_MESA_copy_sub_buffer is always enabled. */
+            __glXEnableExtension(screen->glx_enable_bits,
+                                 "GLX_MESA_copy_sub_buffer");
+
+            LogMessage(X_INFO, "AIGLX: enabled GLX_MESA_copy_sub_buffer\n");
         }
 #endif
 
@@ -423,6 +440,7 @@ initializeExtensions(__GLXDRIscreen * screen)
         if (strcmp(extensions[i]->name, __DRI_TEX_BUFFER) == 0) {
             screen->texBuffer = (const __DRItexBufferExtension *) extensions[i];
             /* GLX_EXT_texture_from_pixmap is always enabled. */
+            LogMessage(X_INFO, "AIGLX: enabled GLX_EXT_texture_from_pixmap\n");
         }
 #endif
         /* Ignore unknown extensions */
@@ -434,6 +452,7 @@ __glXDRIscreenProbe(ScreenPtr pScreen)
 {
     const char *driverName = "swrast";
     __GLXDRIscreen *screen;
+    size_t buffer_size;
 
     screen = calloc(1, sizeof *screen);
     if (screen == NULL)
@@ -445,6 +464,8 @@ __glXDRIscreenProbe(ScreenPtr pScreen)
     screen->base.swapInterval = NULL;
     screen->base.pScreen = pScreen;
 
+    __glXInitExtensionEnableBits(screen->glx_enable_bits);
+
     screen->driver = glxProbeDriver(driverName,
                                     (void **) &screen->core,
                                     __DRI_CORE, __DRI_CORE_VERSION,
@@ -473,6 +494,19 @@ __glXDRIscreenProbe(ScreenPtr pScreen)
 
     __glXScreenInit(&screen->base, pScreen);
 
+    /* The first call simply determines the length of the extension string.
+     * This allows us to allocate some memory to hold the extension string,
+     * but it requires that we call __glXGetExtensionString a second time.
+     */
+    buffer_size = __glXGetExtensionString(screen->glx_enable_bits, NULL);
+    if (buffer_size > 0) {
+        free(screen->base.GLXextensions);
+
+        screen->base.GLXextensions = xnfalloc(buffer_size);
+        (void) __glXGetExtensionString(screen->glx_enable_bits,
+                                       screen->base.GLXextensions);
+    }
+
     screen->base.GLXmajor = 1;
     screen->base.GLXminor = 4;
 
diff --git a/glx/glxscreens.c b/glx/glxscreens.c
index 61d590cc8..6a2382ad4 100644
--- a/glx/glxscreens.c
+++ b/glx/glxscreens.c
@@ -163,18 +163,6 @@ static const char GLServerExtensions[] =
 static char GLXServerVendorName[] = "SGI";
 unsigned glxMajorVersion = SERVER_GLX_MAJOR_VERSION;
 unsigned glxMinorVersion = SERVER_GLX_MINOR_VERSION;
-static char GLXServerExtensions[] =
-    "GLX_ARB_multisample "
-    "GLX_EXT_visual_info "
-    "GLX_EXT_visual_rating "
-    "GLX_EXT_import_context "
-    "GLX_EXT_texture_from_pixmap "
-    "GLX_OML_swap_method " "GLX_SGI_make_current_read "
-#ifndef __APPLE__
-    "GLX_SGIS_multisample "
-#endif
-    "GLX_SGIX_fbconfig "
-    "GLX_SGIX_pbuffer " "GLX_MESA_copy_sub_buffer ";
 
 static Bool
 glxCloseScreen(ScreenPtr pScreen)
@@ -331,7 +319,7 @@ __glXScreenInit(__GLXscreen * pGlxScreen, ScreenPtr pScreen)
     pGlxScreen->pScreen = pScreen;
     pGlxScreen->GLextensions = strdup(GLServerExtensions);
     pGlxScreen->GLXvendor = strdup(GLXServerVendorName);
-    pGlxScreen->GLXextensions = strdup(GLXServerExtensions);
+    pGlxScreen->GLXextensions = strdup("");
 
     /* All GLX providers must support all of the functionality required for at
      * least GLX 1.2.  If the provider supports a higher version, the GLXminor