Allow the configs parameter for eglChooseConfig to be null in shadow

Most of the time, the output parameters for EGL methods are
expected to be non-null. But the `configs` parameter of
`eglChooseConfig` is one of the exceptions. When `configs` is
not null, `eglChooseConfig` fills that with the first
`configSize` configs and fills `numConfig` with the number of
returned configs (no more than `configsSize`). But when `configs`
is_ `null` it fills `numConfigs` with the number of _matching_
configs, ignoring `configsSize`:
https://registry.khronos.org/EGL/sdk/docs/man/html/eglChooseConfig.xhtml

The Android code wrapping this API checks that `attrib_list` and
`num_configs` output arrays are not null, but allows `configs`
to be null (see frameworks/base/core/jni/android_opengl_EGL14.cpp).

PiperOrigin-RevId: 631820937

2 files changed, 18 insertions, 2 deletions

diff --git a/robolectric/src/test/java/org/robolectric/shadows/ShadowEGL14Test.java b/robolectric/src/test/java/org/robolectric/shadows/ShadowEGL14Test.java
index 4da4963cd..459b75b65 100644
--- a/robolectric/src/test/java/org/robolectric/shadows/ShadowEGL14Test.java
+++ b/robolectric/src/test/java/org/robolectric/shadows/ShadowEGL14Test.java
@@ -27,8 +27,10 @@ public final class ShadowEGL14Test {
   }
 
   @Test
-  public void eglChooseConfig() {
+  public void eglChooseConfig_retrieveConfigs() {
     EGLDisplay display = EGL14.eglGetDisplay(EGL14.EGL_DEFAULT_DISPLAY);
+    // When the config array is not null, numConfig is filled with the number of configs returned
+    // (up to the size of the config array).
     EGLConfig[] configs = new EGLConfig[1];
     int[] numConfig = new int[1];
     assertThat(EGL14.eglChooseConfig(display, new int[0], 0, configs, 0, 1, numConfig, 0)).isTrue();
@@ -37,6 +39,16 @@ public final class ShadowEGL14Test {
   }
 
   @Test
+  public void eglChooseConfig_countMatching() {
+    EGLDisplay display = EGL14.eglGetDisplay(EGL14.EGL_DEFAULT_DISPLAY);
+    // When the config array is null, numConfig is filled with the total number of configs matched.
+    EGLConfig[] configs = null;
+    int[] numConfig = new int[1];
+    assertThat(EGL14.eglChooseConfig(display, new int[0], 0, configs, 0, 0, numConfig, 0)).isTrue();
+    assertThat(numConfig[0]).isGreaterThan(0);
+  }
+
+  @Test
   public void eglCreateContext_v2() {
     EGLDisplay display = EGL14.eglGetDisplay(EGL14.EGL_DEFAULT_DISPLAY);
     int[] attribList = {EGL14.EGL_CONTEXT_CLIENT_VERSION, 2, EGL14.EGL_NONE};
diff --git a/shadows/framework/src/main/java/org/robolectric/shadows/ShadowEGL14.java b/shadows/framework/src/main/java/org/robolectric/shadows/ShadowEGL14.java
index 4f488b571..547b9f1ff 100644
--- a/shadows/framework/src/main/java/org/robolectric/shadows/ShadowEGL14.java
+++ b/shadows/framework/src/main/java/org/robolectric/shadows/ShadowEGL14.java
@@ -37,7 +37,11 @@ public class ShadowEGL14 {
       int configSize,
       int[] numConfig,
       int numConfigOffset) {
-    configs[configsOffset] = createEglConfig();
+    // The configs array here can be null, in which case the numConfig output is supposed to be
+    // set to the number of matching configs instead of the number of returned configs.
+    if (configs != null) {
+      configs[configsOffset] = createEglConfig();
+    }
     numConfig[numConfigOffset] = 1;
     return true;
   }