8248560: Specify the behaviour of the ForeignLinker returned by CSupport::getSystemLinker

src/jdk.incubator.foreign/share/classes/jdk/incubator/foreign/Addressable.java

@@ -28,12 +28,12 @@
 /**
  * Represents a type which is <em>addressable</em>. An addressable type is one which can be projected down to
  * a memory address instance (see {@link #address()}). Examples of addressable types are {@link MemorySegment},
- * {@link MemoryAddress}, {@link LibraryLookup.Symbol} and {@link CSupport.VaList}.
+ * {@link MemoryAddress}, {@link LibraryLookup.Symbol} and {@link CLinker.VaList}.
  *
  * @apiNote In the future, if the Java language permits, {@link Addressable}
  * may become a {@code sealed} interface, which would prohibit subclassing except by
  * explicitly permitted types, such as {@link MemorySegment}, {@link MemoryAddress}, {@link LibraryLookup.Symbol}
- * and {@link CSupport.VaList}.
+ * and {@link CLinker.VaList}.
  *
  * @implSpec
  * Implementations of this interface <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>.

src/jdk.incubator.foreign/share/classes/jdk/incubator/foreign/LibraryLookup.java

@@ -38,7 +38,7 @@
  * <p>
  * All symbol instances (see {@link LibraryLookup.Symbol}) generated by a given library lookup object contain a strong reference
  * to said lookup object, therefore preventing library unloading; in turn method handle instances obtained from
- * {@link ForeignLinker#downcallHandle(Addressable, MethodType, FunctionDescriptor)}) also maintain a strong reference
+ * {@link CLinker#downcallHandle(Addressable, MethodType, FunctionDescriptor)}) also maintain a strong reference
  * to the addressable parameter used for their construction. This means that there is always a strong reachability chain
  * from a native method handle to a lookup object (the one that was used to lookup the native library symbol the method handle
  * refers to); this is useful to prevent situations where a native library is unloaded in the middle of a native call.

src/jdk.incubator.foreign/share/classes/jdk/internal/foreign/CABI.java

@@ -0,0 +1,47 @@
+/*
+ *  Copyright (c) 2020, 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 jdk.internal.foreign;
+
+public enum CABI {
+    SysV,
+    Win64,
+    AArch64;
+
+    public static CABI current() {
+        String arch = System.getProperty("os.arch");
+        String os = System.getProperty("os.name");
+        if (arch.equals("amd64") || arch.equals("x86_64")) {
+            if (os.startsWith("Windows")) {
+                return Win64;
+            } else {
+                return SysV;
+            }
+        } else if (arch.equals("aarch64")) {
+            return AArch64;
+        }
+        throw new UnsupportedOperationException("Unsupported os or arch: " + os + ", " + arch);
+    }
+}