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.

include/epoxy/glx_common.h

@@ -31,8 +31,11 @@
 
 #include <stdbool.h>
 
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+
 bool epoxy_has_glx_extension(const char *extension);
-int epoxy_glx_version(void);
+int epoxy_glx_version(Display *dpy, int screen);
 
 #endif /* EPOXY_GLX_COMMON_H */
 

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);

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);

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

test/Makefile.am

@@ -37,8 +37,6 @@ TESTS = \
 	headerguards \
 	$()
 
-XFAIL_TESTS = glx_glxgetprocaddress_nocontext
-
 check_PROGRAMS = $(TESTS)
 
 glx_public_api_LDFLAGS = $(X11_LIBS) $(EPOXY) libglx_common.la

test/glx_glxgetprocaddress_nocontext.c

@@ -45,7 +45,7 @@ main(int argc, char **argv)
     bool pass = true;
 
     dpy = get_display_or_skip();
-    if (epoxy_glx_version() < 14)
+    if (epoxy_glx_version(dpy, 0) < 14)
         errx(77, "GLX version 1.4 required for glXGetProcAddress().\n");
 
     void *func = glXGetProcAddress("glGetString");

test/glx_public_api.c

@@ -48,7 +48,7 @@ test_gl_version(void)
 static bool
 test_glx_version(void)
 {
-    int version = epoxy_glx_version();
+    int version = epoxy_glx_version(dpy, 0);
     const char *version_string;
     int ret;
     int server_major, server_minor;