[waffle] [PATCH 2/4] wayland: fetch wl_egl_* function pointers at wayland_platform_create

[Emil Velikov]

Will be used by the next commit to demote the link-time dependency.
As a result one will not require libwayland-egl.so.1 to be present on
their system unless they want to use WAFFLE_PLATFORM_WAYLAND.

Signed-off-by: Emil Velikov <emil.l.velikov at gmail.com>
---
 src/waffle/wayland/wayland_platform.c | 37 +++++++++++++++++++++++++++++++++++
 src/waffle/wayland/wayland_platform.h | 18 +++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/src/waffle/wayland/wayland_platform.c b/src/waffle/wayland/wayland_platform.c
index 63cfdc2..94c0010 100644
--- a/src/waffle/wayland/wayland_platform.c
+++ b/src/waffle/wayland/wayland_platform.c
@@ -27,6 +27,7 @@
 #define _POSIX_C_SOURCE 200112 // glib feature macro for unsetenv()
 
 #include <stdlib.h>
+#include <dlfcn.h>
 
 #include "waffle_wayland.h"
 
@@ -43,6 +44,8 @@
 #include "wayland_platform.h"
 #include "wayland_window.h"
 
+static const char *libwl_egl_filename = "libwayland-egl.so.1";
+
 static const struct wcore_platform_vtbl wayland_platform_vtbl;
 
 static bool
@@ -50,6 +53,7 @@ wayland_platform_destroy(struct wcore_platform *wc_self)
 {
     struct wayland_platform *self = wayland_platform(wegl_platform(wc_self));
     bool ok = true;
+    int error;
 
     if (!self)
         return true;
@@ -59,6 +63,16 @@ wayland_platform_destroy(struct wcore_platform *wc_self)
     if (self->linux)
         ok &= linux_platform_destroy(self->linux);
 
+    if (self->dl_wl_egl) {
+        error = dlclose(self->dl_wl_egl);
+        if (error) {
+            ok &= false;
+            wcore_errorf(WAFFLE_ERROR_UNKNOWN,
+                         "dlclose(\"%s\") failed: %s",
+                         libwl_egl_filename, dlerror());
+        }
+    }
+
     ok &= wegl_platform_teardown(&self->wegl);
     free(self);
     return ok;
@@ -78,6 +92,29 @@ wayland_platform_create(void)
     if (!ok)
         goto error;
 
+    self->dl_wl_egl = dlopen(libwl_egl_filename, RTLD_LAZY | RTLD_LOCAL);
+    if (!self->dl_wl_egl) {
+        wcore_errorf(WAFFLE_ERROR_FATAL,
+                     "dlopen(\"%s\") failed: %s",
+                     libwl_egl_filename, dlerror());
+        goto error;
+    }
+
+#define RETRIEVE_WL_EGL_SYMBOL(function)                                  \
+    self->function = dlsym(self->dl_wl_egl, #function);                \
+    if (!self->function) {                                             \
+        wcore_errorf(WAFFLE_ERROR_FATAL,                             \
+                     "dlsym(\"%s\", \"" #function "\") failed: %s",    \
+                     libwl_egl_filename, dlerror());                      \
+        goto error;                                                    \
+    }
+
+    RETRIEVE_WL_EGL_SYMBOL(wl_egl_window_create);
+    RETRIEVE_WL_EGL_SYMBOL(wl_egl_window_destroy);
+    RETRIEVE_WL_EGL_SYMBOL(wl_egl_window_resize);
+
+#undef RETRIEVE_WL_EGL_SYMBOL
+
     self->linux = linux_platform_create();
     if (!self->linux)
         goto error;
diff --git a/src/waffle/wayland/wayland_platform.h b/src/waffle/wayland/wayland_platform.h
index c4e870f..574a306 100644
--- a/src/waffle/wayland/wayland_platform.h
+++ b/src/waffle/wayland/wayland_platform.h
@@ -36,10 +36,28 @@
 #include "wcore_util.h"
 
 struct linux_platform;
+struct wl_egl_window;
+struct wl_surface;
 
 struct wayland_platform {
     struct wegl_platform wegl;
     struct linux_platform *linux;
+
+
+    void *dl_wl_egl;
+
+    struct wl_egl_window *
+    (*wl_egl_window_create)(struct wl_surface *surface,
+                            int width, int height);
+
+    void
+    (*wl_egl_window_destroy)(struct wl_egl_window *egl_window);
+
+    void
+    (*wl_egl_window_resize)(struct wl_egl_window *egl_window,
+                            int width, int height,
+                            int dx, int dy);
+
 };
 
 DEFINE_CONTAINER_CAST_FUNC(wayland_platform,
-- 
2.3.0