glx: Implement GLX_EXT_libglvnd (v2)

For the dri2 backend, we depend on xfree86 already, so we can walk the
options for the screen looking for a vendor string from xorg.conf.  For
the swrast backend we don't have that luxury, so just say mesa.  This
extension isn't really meaningful on Windows or OSX yet (since libglvnd
isn't really functional there yet), so on those platforms we don't say
anything and return BadValue for the token from QueryServerString.

v2: Use xnf* allocators when parsing options (Eric and Emil)

Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Signed-off-by: Adam Jackson <ajax@redhat.com>

glx/extension_string.c

@@ -85,6 +85,7 @@ static const struct extension_info known_glx_extensions[] = {
     { GLX(EXT_fbconfig_packed_float),   VER(0,0), N, },
     { GLX(EXT_framebuffer_sRGB),        VER(0,0), N, },
     { GLX(EXT_import_context),          VER(0,0), Y, },
+    { GLX(EXT_libglvnd),                VER(0,0), N, },
     { GLX(EXT_stereo_tree),             VER(0,0), N, },
     { GLX(EXT_texture_from_pixmap),     VER(0,0), N, },
     { GLX(EXT_visual_info),             VER(0,0), Y, },

glx/extension_string.h

@@ -47,6 +47,7 @@ enum {
     EXT_create_context_es2_profile_bit,
     EXT_fbconfig_packed_float_bit,
     EXT_import_context_bit,
+    EXT_libglvnd_bit,
     EXT_stereo_tree_bit,
     EXT_texture_from_pixmap_bit,
     EXT_visual_info_bit,

glx/glxcmds.c

@@ -2444,6 +2444,10 @@ __glXDisp_QueryExtensionsString(__GLXclientState * cl, GLbyte * pc)
     return Success;
 }
 
+#ifndef GLX_VENDOR_NAMES_EXT
+#define GLX_VENDOR_NAMES_EXT 0x20F6
+#endif
+
 int
 __glXDisp_QueryServerString(__GLXclientState * cl, GLbyte * pc)
 {
@@ -2471,6 +2475,12 @@ __glXDisp_QueryServerString(__GLXclientState * cl, GLbyte * pc)
     case GLX_EXTENSIONS:
         ptr = pGlxScreen->GLXextensions;
         break;
+    case GLX_VENDOR_NAMES_EXT:
+        if (pGlxScreen->glvnd) {
+            ptr = pGlxScreen->glvnd;
+            break;
+        }
+        /* else fall through */
     default:
         return BadValue;
     }

glx/glxdri2.c

@@ -934,12 +934,23 @@ initializeExtensions(__GLXscreen * screen)
 /* white lie */
 extern glx_func_ptr glXGetProcAddressARB(const char *);
 
+enum {
+    GLXOPT_VENDOR_LIBRARY,
+};
+
+static const OptionInfoRec GLXOptions[] = {
+    { GLXOPT_VENDOR_LIBRARY, "GlxVendorLibrary", OPTV_STRING, {0}, FALSE },
+    { -1, NULL, OPTV_NONE, {0}, FALSE },
+};
+
 static __GLXscreen *
 __glXDRIscreenProbe(ScreenPtr pScreen)
 {
     const char *driverName, *deviceName;
     __GLXDRIscreen *screen;
     ScrnInfoPtr pScrn = xf86ScreenToScrn(pScreen);
+    const char *glvnd = NULL;
+    OptionInfoPtr options;
 
     screen = calloc(1, sizeof *screen);
     if (screen == NULL)
@@ -985,6 +996,17 @@ __glXDRIscreenProbe(ScreenPtr pScreen)
                                                GLX_PIXMAP_BIT |
                                                GLX_PBUFFER_BIT);
 
+    options = xnfalloc(sizeof(GLXOptions));
+    memcpy(options, GLXOptions, sizeof(GLXOptions));
+    xf86ProcessOptions(pScrn->scrnIndex, pScrn->options, options);
+    glvnd = xf86GetOptValString(options, GLXOPT_VENDOR_LIBRARY);
+    if (glvnd)
+        screen->base.glvnd = xnfstrdup(glvnd);
+    free(options);
+
+    if (!screen->base.glvnd)
+        screen->base.glvnd = strdup("mesa");
+
     __glXScreenInit(&screen->base, pScreen);
 
     screen->enterVT = pScrn->EnterVT;

glx/glxdriswrast.c

@@ -487,6 +487,9 @@ __glXDRIscreenProbe(ScreenPtr pScreen)
                                                GLX_PIXMAP_BIT |
                                                GLX_PBUFFER_BIT);
 
+#if !defined(XQUARTZ) && !defined(WIN32)
+    screen->base.glvnd = strdup("mesa");
+#endif
     __glXScreenInit(&screen->base, pScreen);
 
     __glXsetGetProcAddress(glXGetProcAddressARB);

glx/glxscreens.c

@@ -384,6 +384,9 @@ __glXScreenInit(__GLXscreen * pGlxScreen, ScreenPtr pScreen)
 
     dixSetPrivate(&pScreen->devPrivates, glxScreenPrivateKey, pGlxScreen);
 
+    if (pGlxScreen->glvnd)
+        __glXEnableExtension(pGlxScreen->glx_enable_bits, "GLX_EXT_libglvnd");
+
     i = __glXGetExtensionString(pGlxScreen->glx_enable_bits, NULL);
     if (i > 0) {
         pGlxScreen->GLXextensions = xnfalloc(i);
@@ -396,6 +399,7 @@ __glXScreenInit(__GLXscreen * pGlxScreen, ScreenPtr pScreen)
 void
 __glXScreenDestroy(__GLXscreen * screen)
 {
+    free(screen->glvnd);
     free(screen->GLXextensions);
     free(screen->GLextensions);
     free(screen->visuals);

glx/glxscreens.h

@@ -143,6 +143,7 @@ struct __GLXscreen {
 
     char *GLextensions;
     char *GLXextensions;
+    char *glvnd;
     unsigned char glx_enable_bits[__GLX_EXT_BYTES];
 
     Bool (*CloseScreen) (ScreenPtr pScreen);

hw/xfree86/man/xorg.conf.man

@@ -2039,6 +2039,12 @@ Note that disabling an operation will have no effect if the operation is
 not accelerated (whether due to lack of support in the hardware or in the
 driver).
 .TP 7
+.BI "Option \*qGlxVendorLibrary\*q \*q" string \*q
+This option specifies a space-separated list of OpenGL vendor libraries to
+use for the screen. This may be used to select an alternate implementation
+for development, debugging, or alternate feature sets.
+Default: mesa.
+.TP 7
 .BI "Option \*qInitPrimary\*q \*q" boolean \*q
 Use the Int10 module to initialize the primary graphics card.
 Normally, only secondary cards are soft-booted using the Int10 module, as the