svm: workaround for "JDK-8365807: (fs) Two-arg UnixFileAttributes.getIfExists should not use exception for control flow" [GR-69415]

Author: zapster

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/jdk/Target_sun_nio_fs_UnixNativeDispatcher.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2025, 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package com.oracle.svm.core.jdk;
+
+import static com.oracle.svm.core.jdk.Helper_sun_nio_fs_UnixNativeDispatcher.init1;
+
+import com.oracle.svm.core.annotate.Substitute;
+import com.oracle.svm.core.annotate.TargetClass;
+
+@TargetClass(className = "sun.nio.fs.UnixNativeDispatcher", onlyWith = NonWindowsOS.class)
+final class Target_sun_nio_fs_UnixNativeDispatcher {
+
+    /**
+     * Wraps the original native {@code init()} call with a pthread mutex. This is a workaround for
+     * GR-69415. The assumption is that there is a race condition when multiple isolates call the
+     * static initializer of {@code UnixNativeDispatcher} and thus the native {@code init} function
+     * concurrently. All those calls operate on the same global C variables so multiple isolates can
+     * interfere with each other.
+     */
+    @Substitute
+    static int init() {
+        return init1(Target_sun_nio_fs_UnixNativeDispatcher.class);
+    }
+}
+
+final class Helper_sun_nio_fs_UnixNativeDispatcher {
+    /**
+     * A C-level thread-safe wrapper for the original
+     * {@link Target_sun_nio_fs_UnixNativeDispatcher#init()}. Implementation is in
+     * {@code UnixNativeDispatcher.c}.
+     */
+    static native int init1(Class<?> targetSunNioFsUnixNativeDispatcherClass);
+}

substratevm/src/com.oracle.svm.native.jvm.posix/src/UnixNativeDispatcherHelper.c

@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2025, 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation. Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#include <jni.h>
+#include <pthread.h>
+
+// The original init function
+jint JNICALL Java_sun_nio_fs_UnixNativeDispatcher_init(JNIEnv* env, jclass this);
+
+// cached capabilities
+static jint capabilities = 0;
+
+// Global/static initialization flag and mutex
+static jboolean initialized = JNI_FALSE;
+static pthread_mutex_t init_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+JNIEXPORT jint JNICALL Java_com_oracle_svm_core_jdk_Helper_1sun_1nio_1fs_1UnixNativeDispatcher_init1(JNIEnv* env, jclass this, jclass unixNativeDispatcherClass) {
+    pthread_mutex_lock(&init_mutex);
+    if (initialized == JNI_FALSE) {
+        capabilities = Java_sun_nio_fs_UnixNativeDispatcher_init(env, unixNativeDispatcherClass);
+        // initialization done
+        initialized = JNI_TRUE;
+    }
+    pthread_mutex_unlock(&init_mutex);
+    return capabilities;
+}