glx: Add an optional function call for getting the DRI driver interface.

The previous interface relied on a static struct, which meant that the
driver didn't get a chance to edit the struct before the struct got used.
For megadrivers, I want struct specific to the driver being loaded.

v2: Fix the prototype in the docs (caught by Marek).  Since the driver
    name was in the function, we didn't need to also pass it in.
v3: Fix asprintf error checking (caught by Matt's gcc).

Reviewed-by: Matt Turner <[email protected]> (v1)
Reviewed-by: Chad Versace <[email protected]>
Reviewed-by: Emil Velikov <[email protected]>

1 files changed, 16 insertions, 1 deletions

diff --git a/src/glx/dri_common.c b/src/glx/dri_common.c
index f1d1164571e..22ba248cfb0 100644
--- a/src/glx/dri_common.c
+++ b/src/glx/dri_common.c
@@ -188,9 +188,24 @@ driOpenDriver(const char *driverName)
 }
 
 _X_HIDDEN const __DRIextension **
-driGetDriverExtensions(void *handle)
+driGetDriverExtensions(void *handle, const char *driver_name)
 {
    const __DRIextension **extensions = NULL;
+   const __DRIextension **(*get_extensions)(void);
+   char *get_extensions_name;
+
+   if (asprintf(&get_extensions_name, "%s_%s",
+                __DRI_DRIVER_GET_EXTENSIONS, driver_name) != -1) {
+      get_extensions = dlsym(handle, get_extensions_name);
+      if (get_extensions) {
+         free(get_extensions_name);
+         return get_extensions();
+      } else {
+         InfoMessageF("driver does not expose %s(): %s\n",
+                      get_extensions_name, dlerror());
+         free(get_extensions_name);
+      }
+   }
 
    extensions = dlsym(handle, __DRI_DRIVER_EXTENSIONS);
    if (extensions == NULL) {