[waffle] [PATCH 6/7] glx: fetch the libGL function pointers at glx_platform_create

[Emil Velikov]

Thus way with a follow up commit we can use them and eliminate the
link dependency from waffle.

Signed-off-by: Emil Velikov <emil.l.velikov at gmail.com>
---
 src/waffle/glx/glx_platform.c | 45 +++++++++++++++++++++++++++++++++++++++++++
 src/waffle/glx/glx_platform.h | 25 ++++++++++++++++++++----
 2 files changed, 66 insertions(+), 4 deletions(-)

diff --git a/src/waffle/glx/glx_platform.c b/src/waffle/glx/glx_platform.c
index 804c275..ae0cf46 100644
--- a/src/waffle/glx/glx_platform.c
+++ b/src/waffle/glx/glx_platform.c
@@ -24,6 +24,7 @@
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include <stdlib.h>
+#include <dlfcn.h>
 
 #include "wcore_error.h"
 
@@ -36,6 +37,8 @@
 #include "glx_window.h"
 #include "glx_wrappers.h"
 
+static const char *libGL_filename = "libGL.so.1";
+
 static const struct wcore_platform_vtbl glx_platform_vtbl;
 
 static bool
@@ -43,6 +46,7 @@ glx_platform_destroy(struct wcore_platform *wc_self)
 {
     struct glx_platform *self = glx_platform(wc_self);
     bool ok = true;
+    int error = 0;
 
     if (!self)
         return true;
@@ -50,6 +54,16 @@ glx_platform_destroy(struct wcore_platform *wc_self)
     if (self->linux)
         ok &= linux_platform_destroy(self->linux);
 
+    if (self->glxHandle) {
+        error = dlclose(self->glxHandle);
+        if (error) {
+            ok &= false;
+            wcore_errorf(WAFFLE_ERROR_UNKNOWN,
+                         "dlclose(\"%s\") failed: %s",
+                         libGL_filename, dlerror());
+        }
+    }
+
     ok &= wcore_platform_teardown(wc_self);
     free(self);
     return ok;
@@ -69,6 +83,37 @@ glx_platform_create(void)
     if (!ok)
         goto error;
 
+    self->glxHandle = dlopen(libGL_filename, RTLD_LAZY | RTLD_LOCAL);
+    if (!self->glxHandle) {
+        wcore_errorf(WAFFLE_ERROR_FATAL,
+                     "dlopen(\"%s\") failed: %s",
+                     libGL_filename, dlerror());
+        goto error;
+    }
+
+#define RETRIEVE_GLX_SYMBOL(function)                                  \
+    self->function = dlsym(self->glxHandle, #function);                \
+    if (!self->function) {                                             \
+        wcore_errorf(WAFFLE_ERROR_FATAL,                             \
+                     "dlsym(\"%s\", \"" #function "\") failed: %s",    \
+                     libGL_filename, dlerror());                      \
+        goto error;                                                    \
+    }
+
+    RETRIEVE_GLX_SYMBOL(glXCreateNewContext);
+    RETRIEVE_GLX_SYMBOL(glXDestroyContext);
+    RETRIEVE_GLX_SYMBOL(glXMakeCurrent);
+
+    RETRIEVE_GLX_SYMBOL(glXQueryExtensionsString);
+    RETRIEVE_GLX_SYMBOL(glXGetProcAddress);
+
+    RETRIEVE_GLX_SYMBOL(glXGetVisualFromFBConfig);
+    RETRIEVE_GLX_SYMBOL(glXGetFBConfigAttrib);
+    RETRIEVE_GLX_SYMBOL(glXChooseFBConfig);
+
+    RETRIEVE_GLX_SYMBOL(glXSwapBuffers);
+#undef RETRIEVE_GLX_SYMBOL
+
     self->linux = linux_platform_create();
     if (!self->linux)
         goto error;
diff --git a/src/waffle/glx/glx_platform.h b/src/waffle/glx/glx_platform.h
index 58519e8..36ddff6 100644
--- a/src/waffle/glx/glx_platform.h
+++ b/src/waffle/glx/glx_platform.h
@@ -26,12 +26,8 @@
 #pragma once
 
 #include <GL/glx.h>
-#include <X11/Xlib.h>
-#include <xcb/xcb.h>
 #undef linux
 
-#include "waffle_glx.h"
-
 #include "wcore_platform.h"
 #include "wcore_util.h"
 
@@ -41,6 +37,27 @@ struct glx_platform {
     struct wcore_platform wcore;
     struct linux_platform *linux;
 
+    // glX function pointers
+    void *glxHandle;
+
+    GLXContext (*glXCreateNewContext)(Display *dpy, GLXFBConfig config,
+                                      int renderType, GLXContext shareList,
+                                      Bool direct);
+    void (*glXDestroyContext)(Display *dpy, GLXContext ctx);
+    Bool (*glXMakeCurrent)(Display *dpy, GLXDrawable drawable, GLXContext ctx);
+
+    const char *(*glXQueryExtensionsString)(Display *dpy, int screen);
+    void *(*glXGetProcAddress)(const GLubyte *procname);
+
+    XVisualInfo *(*glXGetVisualFromFBConfig)(Display *dpy, GLXFBConfig config);
+    int (*glXGetFBConfigAttrib)(Display *dpy, GLXFBConfig config,
+                                int attribute, int *value);
+    GLXFBConfig *(*glXChooseFBConfig)(Display *dpy, int screen,
+                                      const int *attribList, int *nitems);
+
+    void (*glXSwapBuffers)(Display *dpy, GLXDrawable drawable);
+
+
     PFNGLXCREATECONTEXTATTRIBSARBPROC glXCreateContextAttribsARB;
 };
 
-- 
2.1.3