feat(core) EspressoVM compatibility

modules/lwjgl/core/src/main/java/org/lwjgl/system/ThreadLocalUtil.java

@@ -90,6 +90,18 @@ be easy to workaround (attaching the agent at startup, making sure no contexts a
     /** The global JNIEnv. */
     private static final long JNI_NATIVE_INTERFACE = memGetAddress(getThreadJNIEnv());
 
+    /** The offset in JNIEnv at which to store the pointer to the capabilities array. */
+    private static final int CAPABILITIES_OFFSET = 3 * POINTER_SIZE;
+
+    /**
+     * Initial value of reserved3
+     *
+     * - OpenJDK: NULL
+     * - EspressoVM: NULL
+     * - GraalVM Native Image: pointer to UnimplementedWithJNIEnvArgument function (see #875)
+     */
+    private static final long RESERVED3_NULL = memGetAddress(JNI_NATIVE_INTERFACE + CAPABILITIES_OFFSET);
+
     /** The number of pointers in the JNIEnv struct. */
     private static final int JNI_NATIVE_INTERFACE_FUNCTION_COUNT;
 
@@ -103,9 +115,6 @@ be easy to workaround (attaching the agent at startup, making sure no contexts a
      */
     private static long FUNCTION_MISSING_ABORT_TABLE = NULL;
 
-    /** The offset in JNIEnv at which to store the pointer to the capabilities array. */
-    private static final int CAPABILITIES_OFFSET = 3 * POINTER_SIZE;
-
     static {
         int JNI_VERSION = GetVersion();
 
@@ -184,21 +193,27 @@ public static void setCapabilities(long capabilities) {
 
     // Ensures FUNCTION_MISSING_ABORT will be called even if no context is current,
     public static void setFunctionMissingAddresses(int functionCount) {
-        // OpenJDK: NULL
-        // GraalVM Native Image: pointer to UnimplementedWithJNIEnvArgument function (see #875)
-        long RESERVED0_NULL = memGetAddress(JNI_NATIVE_INTERFACE);
-
         long ptr = JNI_NATIVE_INTERFACE + CAPABILITIES_OFFSET;
 
+        // aka. reserved3
         long currentTable = memGetAddress(ptr);
+
         if (functionCount == 0) {
-            if (currentTable != RESERVED0_NULL) {
+            if (currentTable == FUNCTION_MISSING_ABORT) {
                 FUNCTION_MISSING_ABORT_TABLE = NULL;
                 getAllocator().free(currentTable);
-                memPutAddress(ptr, NULL);
+                memPutAddress(ptr, RESERVED3_NULL);
             }
         } else {
-            if (currentTable != RESERVED0_NULL) {
+            // OpenJDK: NULL
+            // EspressoVM: pointer to VM internal
+            // GraalVM Native Image: pointer to UnimplementedWithJNIEnvArgument function (see #875)
+            long RESERVED0_NULL = memGetAddress(JNI_NATIVE_INTERFACE);
+
+            boolean slotAvailable = currentTable == NULL; // on HotSpot or Espresso
+            slotAvailable |= currentTable == RESERVED0_NULL; // on Native Image
+
+            if (!slotAvailable) {
                 throw new IllegalStateException("setFunctionMissingAddresses has been called already");
             }
             if (currentTable != NULL) {
@@ -233,4 +248,4 @@ public static boolean areCapabilitiesDifferent(PointerBuffer ref, PointerBuffer
         return false;
     }
 
-}
+}