Fix bug in public entrypoint for epoxy_glx_version()

Unfortunately, for GLX 1.4+ entrypoints (just glxGetProcAddress
currently) or extensions, if there isn't a context bound then we don't
have a dpy and screen available to provide useful debug messages.  Oh
well.

3 files changed, 22 insertions, 7 deletions

diff --git a/src/dispatch_common.c b/src/dispatch_common.c
index 4bd432e..a32b30b 100644
--- a/src/dispatch_common.c
+++ b/src/dispatch_common.c
@@ -138,21 +138,35 @@ epoxy_is_glx(void)
     return true; /* XXX */
 }
 
-PUBLIC int
-epoxy_glx_version(void)
+/**
+ * If we can determine the GLX version from the current context, then
+ * return that, otherwise return a version that will just send us on
+ * to dlsym() or get_proc_address().
+ */
+int
+epoxy_conservative_glx_version(void)
 {
     Display *dpy = glXGetCurrentDisplay();
     GLXContext ctx = glXGetCurrentContext();
+    int screen;
+
+    if (!dpy || !ctx)
+        return 14;
+
+    glXQueryContext(dpy, ctx, GLX_SCREEN, &screen);
+
+    return epoxy_glx_version(dpy, screen);
+}
+
+PUBLIC int
+epoxy_glx_version(Display *dpy, int screen)
+{
     int server_major, server_minor;
     int client_major, client_minor;
     int server, client;
     const char *version_string;
-    int screen = 0;
     int ret;
 
-    /* XXX: What if there's no current context? */
-    glXQueryContext(dpy, ctx, GLX_SCREEN, &screen);
-
     version_string = glXQueryServerString(dpy, screen, GLX_VERSION);
     ret = sscanf(version_string, "%d.%d", &server_major, &server_minor);
     assert(ret == 2);
diff --git a/src/dispatch_common.h b/src/dispatch_common.h
index cf90248..ed3fa5b 100644
--- a/src/dispatch_common.h
+++ b/src/dispatch_common.h
@@ -49,6 +49,7 @@ struct api {
 bool epoxy_is_glx(void);
 
 void *epoxy_get_proc_address(const char *name);
+int epoxy_conservative_glx_version(void);
 void *epoxy_dlsym(const char *name);
 void epoxy_glx_autoinit(void);
 void epoxy_platform_autoinit(void);
diff --git a/src/gen_dispatch.py b/src/gen_dispatch.py
index b402745..8b9cc54 100755
--- a/src/gen_dispatch.py
+++ b/src/gen_dispatch.py
@@ -292,7 +292,7 @@ class Generator(object):
                 # We could just always use GPA, but dlsym() is a more
                 # efficient lookup.
                 if version > 13:
-                    condition = condition + ' && epoxy_glx_version() >= {0}'.format(version)
+                    condition = condition + ' && epoxy_conservative_glx_version() >= {0}'.format(version)
                     loader = self.gpa_loader
                 else:
                     loader = self.dlsym_loader