gbm: fetch the libgbm function pointers at wgbm_platform_init

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@gmail.com>
Reviewed-by: Chad Versace <chad.versace@linux.intel.com>

2 files changed, 59 insertions, 1 deletions

diff --git a/src/waffle/gbm/wgbm_platform.c b/src/waffle/gbm/wgbm_platform.c
index 4c224ac..981c366 100644
--- a/src/waffle/gbm/wgbm_platform.c
+++ b/src/waffle/gbm/wgbm_platform.c
@@ -23,10 +23,10 @@
 // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-#define __GBM__ 1
 #define _POSIX_C_SOURCE 200112 // glib feature macro for unsetenv()
 
 #include <stdlib.h>
+#include <dlfcn.h>
 
 #include "wcore_error.h"
 
@@ -42,6 +42,8 @@
 #include "wgbm_platform.h"
 #include "wgbm_window.h"
 
+static const char *libgbm_filename = "libgbm.so.1";
+
 static const struct wcore_platform_vtbl wgbm_platform_vtbl;
 
 static bool
@@ -49,6 +51,7 @@ wgbm_platform_destroy(struct wcore_platform *wc_self)
 {
     struct wgbm_platform *self = wgbm_platform(wegl_platform(wc_self));
     bool ok = true;
+    int error = 0;
 
     if (!self)
         return true;
@@ -58,6 +61,16 @@ wgbm_platform_destroy(struct wcore_platform *wc_self)
     if (self->linux)
         ok &= linux_platform_destroy(self->linux);
 
+    if (self->gbmHandle) {
+        error = dlclose(self->gbmHandle);
+        if (error) {
+            ok &= false;
+            wcore_errorf(WAFFLE_ERROR_UNKNOWN,
+                         "dlclose(\"%s\") failed: %s",
+                         libgbm_filename, dlerror());
+        }
+    }
+
     ok &= wegl_platform_teardown(&self->wegl);
     free(self);
     return ok;
@@ -77,6 +90,34 @@ wgbm_platform_create(void)
     if (!ok)
         goto error;
 
+    self->gbmHandle = dlopen(libgbm_filename, RTLD_LAZY | RTLD_LOCAL);
+    if (!self->gbmHandle) {
+        wcore_errorf(WAFFLE_ERROR_FATAL,
+                     "dlopen(\"%s\") failed: %s",
+                     libgbm_filename, dlerror());
+        goto error;
+    }
+
+#define RETRIEVE_GBM_SYMBOL(function)                                  \
+    self->function = dlsym(self->gbmHandle, #function);                \
+    if (!self->function) {                                             \
+        wcore_errorf(WAFFLE_ERROR_FATAL,                             \
+                     "dlsym(\"%s\", \"" #function "\") failed: %s",    \
+                     libgbm_filename, dlerror());                      \
+        goto error;                                                    \
+    }
+
+    RETRIEVE_GBM_SYMBOL(gbm_create_device);
+    RETRIEVE_GBM_SYMBOL(gbm_device_get_fd);
+    RETRIEVE_GBM_SYMBOL(gbm_device_destroy);
+
+    RETRIEVE_GBM_SYMBOL(gbm_surface_create);
+    RETRIEVE_GBM_SYMBOL(gbm_surface_destroy);
+
+    RETRIEVE_GBM_SYMBOL(gbm_surface_lock_front_buffer);
+    RETRIEVE_GBM_SYMBOL(gbm_surface_release_buffer);
+#undef RETRIEVE_GBM_SYMBOL
+
     self->linux = linux_platform_create();
     if (!self->linux)
         goto error;
diff --git a/src/waffle/gbm/wgbm_platform.h b/src/waffle/gbm/wgbm_platform.h
index 11a5867..259eb19 100644
--- a/src/waffle/gbm/wgbm_platform.h
+++ b/src/waffle/gbm/wgbm_platform.h
@@ -27,6 +27,7 @@
 
 #include <stdbool.h>
 #include <stdlib.h>
+#include <gbm.h>
 
 #undef linux
 
@@ -38,6 +39,22 @@ struct linux_platform;
 struct wgbm_platform {
     struct wegl_platform wegl;
     struct linux_platform *linux;
+
+    // GBM function pointers
+    void *gbmHandle;
+
+    struct gbm_device *(*gbm_create_device)(int fd);
+    int (*gbm_device_get_fd)(struct gbm_device *gbm);
+    void (*gbm_device_destroy)(struct gbm_device *gbm);
+
+    struct gbm_surface *(*gbm_surface_create)(struct gbm_device *gbm,
+                                              uint32_t width, uint32_t height,
+                                              uint32_t format, uint32_t flags);
+    void (*gbm_surface_destroy)(struct gbm_surface *surface);
+
+    struct gbm_bo *(*gbm_surface_lock_front_buffer)(struct gbm_surface *surface);
+    void (*gbm_surface_release_buffer)(struct gbm_surface *surface,
+                                       struct gbm_bo *bo);
 };
 
 DEFINE_CONTAINER_CAST_FUNC(wgbm_platform,