vo_opengl: egl: handle potential eglChooseConfig failures

This is actually a pretty important fix. eglChooseConfig() might be the
first thing that fails when porobing for desktop GL / ES2 / ES3 support,
because EGL_RENDERABLE_TYPE is set values specific to the underlying
APIs.

Not sure how the hell this worked before. EGL 1.4 implementations
certainly could fail the call with EGL_BAD_ATTRIBUTE if
EGL_RENDERABLE_TYPE has EGL_OPENGL_ES3_BIT set. It's quite possible that
many EGL implementations tolerate invalid EGLConfig values steming from
uininitialized EGLConfig values (and eglCreateWindowSurface() even is
specified to return EGL_BAD_CONFIG error code for "not valid"
EGLConfigs).

1 files changed, 10 insertions, 11 deletions

diff --git a/video/out/opengl/egl_helpers.c b/video/out/opengl/egl_helpers.c
index 3d937a57aa..05f594f4e0 100644
--- a/video/out/opengl/egl_helpers.c
+++ b/video/out/opengl/egl_helpers.c
@@ -70,24 +70,23 @@ static bool create_context(EGLDisplay display, struct mp_log *log, bool probing,
         EGL_NONE
     };
 
-    EGLint config_count;
-    EGLConfig *configs = NULL;
+    EGLint num_configs;
+    if (!eglChooseConfig(display, attributes, NULL, 0, &num_configs))
+        num_configs = 0;
 
-    eglChooseConfig(display, attributes, NULL, 0, &config_count);
+    EGLConfig *configs = talloc_array(NULL, EGLConfig, num_configs);
+    if (!eglChooseConfig(display, attributes, configs, num_configs, &num_configs))
+        num_configs = 0;
 
-    if (config_count) {
-        configs = talloc_array(NULL, EGLConfig, config_count);
-        eglChooseConfig(display, attributes, configs, config_count, &config_count);
-    }
-
-    if (!config_count) {
-        mp_msg(log, msgl, "Could not find EGL configuration!\n");
+    if (!num_configs) {
+        talloc_free(configs);
+        mp_msg(log, msgl, "Could not choose EGLConfig!\n");
         return false;
     }
 
     int chosen = 0;
     if (opts->refine_config)
-        chosen = opts->refine_config(opts->user_data, configs, config_count);
+        chosen = opts->refine_config(opts->user_data, configs, num_configs);
     EGLConfig config = configs[chosen];
 
     talloc_free(configs);