[Mesa-dev] [PATCH 5/5] egl/android: Change order of EGLConfig generation

[Chad Versace]

Many Android apps (such as Google's official NDK GLES2 example app), and
even portions the core framework code (such as SystemServiceManager in
Nougat), incorrectly choose their EGLConfig.  They neglect to match the
EGLConfig's EGL_NATIVE_VISUAL_ID against the window's native format, and
instead choose the first EGLConfig whose channel sizes match those of
the native window format while ignoring the channel *ordering*.

We can detect such buggy clients in logcat when they call
eglCreateSurface, by detecting the mismatch between the EGLConfig's
format and the window's format.

As a workaround, this patch changes the order of EGLConfig generation
such that all EGLConfigs for HAL pixel format i precede those for HAL
pixel format i+1. In my (chadversary) testing on Android Nougat, this
was good enough to pacify the buggy clients.
---
 src/egl/drivers/dri2/platform_android.c | 32 +++++++++++++++++++++++++-------
 1 file changed, 25 insertions(+), 7 deletions(-)

diff --git a/src/egl/drivers/dri2/platform_android.c b/src/egl/drivers/dri2/platform_android.c
index fcf29bce713..c294691f291 100644
--- a/src/egl/drivers/dri2/platform_android.c
+++ b/src/egl/drivers/dri2/platform_android.c
@@ -1039,23 +1039,41 @@ droid_add_configs_for_visuals(_EGLDriver *drv, _EGLDisplay *dpy)
    unsigned int format_count[ARRAY_SIZE(visuals)] = { 0 };
    int config_count = 0;
 
-   for (int i = 0; dri2_dpy->driver_configs[i]; i++) {
-      for (int j = 0; j < ARRAY_SIZE(visuals); j++) {
+   /* The nesting of loops is significant here. Also significant is the order
+    * of the HAL pixel formats. Many Android apps (such as Google's official
+    * NDK GLES2 example app), and even portions the core framework code (such
+    * as SystemServiceManager in Nougat), incorrectly choose their EGLConfig.
+    * They neglect to match the EGLConfig's EGL_NATIVE_VISUAL_ID against the
+    * window's native format, and instead choose the first EGLConfig whose
+    * channel sizes match those of the native window format while ignoring the
+    * channel *ordering*.
+    *
+    * We can detect such buggy clients in logcat when they call
+    * eglCreateSurface, by detecting the mismatch between the EGLConfig's
+    * format and the window's format.
+    *
+    * As a workaround, we generate EGLConfigs such that all EGLConfigs for HAL
+    * pixel format i precede those for HAL pixel format i+1. In my
+    * (chadversary) testing on Android Nougat, this was good enough to pacify
+    * the buggy clients.
+    */
+   for (int i = 0; i < ARRAY_SIZE(visuals); i++) {
+      for (int j = 0; dri2_dpy->driver_configs[j]; j++) {
          const EGLint config_attrs[] = {
-           EGL_NATIVE_VISUAL_ID,   visuals[j].format,
-           EGL_NATIVE_VISUAL_TYPE, visuals[j].format,
+           EGL_NATIVE_VISUAL_ID,   visuals[i].format,
+           EGL_NATIVE_VISUAL_TYPE, visuals[i].format,
            EGL_FRAMEBUFFER_TARGET_ANDROID, EGL_TRUE,
            EGL_RECORDABLE_ANDROID, EGL_TRUE,
            EGL_NONE
          };
 
          struct dri2_egl_config *dri2_conf =
-             dri2_add_config(dpy, dri2_dpy->driver_configs[i],
+             dri2_add_config(dpy, dri2_dpy->driver_configs[j],
                              config_count + 1, surface_type, config_attrs,
-                             visuals[j].rgba_masks);
+                             visuals[i].rgba_masks);
          if (dri2_conf) {
             config_count++;
-            format_count[j]++;
+            format_count[i]++;
          }
       }
    }
-- 
2.13.0