ui/egl: fix make_context_current() callback return value

eglMakeCurrent() returns 1/EGL_TRUE on success. This is not what the
callback expects, where 0 indicates success.

While at it, print the EGL error to ease debugging.

As with virgl_renderer_callbacks, the return value is now checked since
version >= 4:
https://gitlab.freedesktop.org/virgl/virglrenderer/-/commit/7f09e6bf0c6ceea6727bd0049781256a28cab0e5

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20230606115658.677673-3-marcandre.lureau@redhat.com>

ui/egl-context.c

@@ -1,4 +1,5 @@
 #include "qemu/osdep.h"
+#include "qemu/error-report.h"
 #include "ui/egl-context.h"
 
 QEMUGLContext qemu_egl_create_context(DisplayGLCtx *dgc,
@@ -32,6 +33,11 @@ void qemu_egl_destroy_context(DisplayGLCtx *dgc, QEMUGLContext ctx)
 int qemu_egl_make_context_current(DisplayGLCtx *dgc,
                                   QEMUGLContext ctx)
 {
-   return eglMakeCurrent(qemu_egl_display,
-                         EGL_NO_SURFACE, EGL_NO_SURFACE, ctx);
+   if (!eglMakeCurrent(qemu_egl_display,
+                       EGL_NO_SURFACE, EGL_NO_SURFACE, ctx)) {
+        error_report("egl: eglMakeCurrent failed: %s", qemu_egl_get_error_string());
+        return -1;
+   }
+
+   return 0;
 }

ui/gtk-egl.c

@@ -13,6 +13,7 @@
 
 #include "qemu/osdep.h"
 #include "qemu/main-loop.h"
+#include "qemu/error-report.h"
 
 #include "trace.h"
 
@@ -369,6 +370,11 @@ int gd_egl_make_current(DisplayGLCtx *dgc,
 {
     VirtualConsole *vc = container_of(dgc, VirtualConsole, gfx.dgc);
 
-    return eglMakeCurrent(qemu_egl_display, vc->gfx.esurface,
-                          vc->gfx.esurface, ctx);
+    if (!eglMakeCurrent(qemu_egl_display, vc->gfx.esurface,
+                        vc->gfx.esurface, ctx)) {
+        error_report("egl: eglMakeCurrent failed: %s", qemu_egl_get_error_string());
+        return -1;
+    }
+
+    return 0;
 }