IO and additional FileSystem substitutions:

- DirectoryStream implementation by setting a host Iterator and Stream as hidden host reference then proxying all methods to the native world where we retrieve the host object and do the semantics of the function.
- FileDisptacherImpl now has a TruffleDispatcher as a field to avoid code duplication. And generally the substitutions in the dispatcher classes just link against the appropriate methods in TruffleIO.
- ReadV and WriteV implementation by retrieving the underlying direct bytebuffers of the native struct.
- Refactoring of TruffleIO: Now all different readBytes and writeBytes go to one single method respectively where the error handling and return value translation is done. There we now also handle the unavailable flag correctly.

Author: Elia Trachsel

espresso/src/com.oracle.truffle.espresso.io/src/sun/nio/ch/DefaultAsynchronousChannelProvider.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2023, 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.
+ *
+ * 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 sun.nio.ch;
+
+import java.nio.channels.spi.AsynchronousChannelProvider;
+
+public final class DefaultAsynchronousChannelProvider {
+
+    /**
+     * Prevent instantiation.
+     */
+    private DefaultAsynchronousChannelProvider() {
+    }
+
+    /**
+     * Returns the default AsynchronousChannelProvider.
+     */
+    public static AsynchronousChannelProvider create() {
+        return new DummyAsynchronousChannelProvider();
+    }
+
+}

espresso/src/com.oracle.truffle.espresso.io/src/sun/nio/ch/DummyAsynchronousChannelProvider.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2023, 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.
+ *
+ * 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 sun.nio.ch;
+
+import java.io.IOException;
+import java.nio.channels.AsynchronousChannelGroup;
+import java.nio.channels.AsynchronousServerSocketChannel;
+import java.nio.channels.AsynchronousSocketChannel;
+import java.nio.channels.spi.AsynchronousChannelProvider;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.ThreadFactory;
+
+public class DummyAsynchronousChannelProvider extends AsynchronousChannelProvider {
+    @Override
+    public AsynchronousChannelGroup openAsynchronousChannelGroup(int nThreads, ThreadFactory threadFactory) throws IOException {
+        return null;
+    }
+
+    @Override
+    public AsynchronousChannelGroup openAsynchronousChannelGroup(ExecutorService executor, int initialSize) throws IOException {
+        return null;
+    }
+
+    @Override
+    public AsynchronousServerSocketChannel openAsynchronousServerSocketChannel(AsynchronousChannelGroup group) throws IOException {
+        return null;
+    }
+
+    @Override
+    public AsynchronousSocketChannel openAsynchronousSocketChannel(AsynchronousChannelGroup group) throws IOException {
+        return null;
+    }
+}

espresso/src/com.oracle.truffle.espresso.io/src/sun/nio/ch/FileDispatcherImpl.java

@@ -37,7 +37,8 @@
  * This file must be compatible with 21+
  */
 final class FileDispatcherImpl extends sun.nio.ch.FileDispatcher {
-
+    // to avoid code duplication of NativeDispatcher operations
+    private final TruffleDispatcher truffleDispatcher = new TruffleDispatcher();
     static {
         sun.nio.ch.IOUtil.load();
     }
@@ -105,27 +106,27 @@ int setDirectIO(FileDescriptor fd, String path) {
 
     @Override
     int read(FileDescriptor fd, long address, int len) throws IOException {
-        return read0(fd, address, len);
+        return truffleDispatcher.read(fd, address, len);
     }
 
     @Override
     long readv(FileDescriptor fd, long address, int len) throws IOException {
-        return readv0(fd, address, len);
+        return truffleDispatcher.readv(fd, address, len);
     }
 
     @Override
     int write(FileDescriptor fd, long address, int len) throws IOException {
-        return write0(fd, address, len);
+        return truffleDispatcher.write(fd, address, len);
     }
 
     @Override
     long writev(FileDescriptor fd, long address, int len) throws IOException {
-        return writev0(fd, address, len);
+        return truffleDispatcher.writev(fd, address, len);
     }
 
     @Override
     void close(FileDescriptor fd) throws IOException {
-        close0(fd);
+        truffleDispatcher.close(fd);
     }
 
     @Override
@@ -212,16 +213,6 @@ boolean isOther(FileDescriptor fd) throws IOException {
 
     private static native long size0(FileDescriptor fd) throws IOException;
 
-    private static native int read0(FileDescriptor fd, long address, int len) throws IOException;
-
-    private static native int readv0(FileDescriptor fd, long address, int len) throws IOException;
-
-    private static native int write0(FileDescriptor fd, long address, int len) throws IOException;
-
-    private static native int writev0(FileDescriptor fd, long address, int len) throws IOException;
-
-    private static native void close0(FileDescriptor fd) throws IOException;
-
     private static native int pread0(FileDescriptor fd, long address, int len, long position) throws IOException;
 
     private static native int pwrite0(FileDescriptor fd, long address, int len, long position) throws IOException;

espresso/src/com.oracle.truffle.espresso.io/src/sun/nio/ch/SocketDispatcher.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2023, 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.
+ *
+ * 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 sun.nio.ch;
+
+class SocketDispatcher extends TruffleDispatcher {
+}

espresso/src/com.oracle.truffle.espresso.io/src/sun/nio/ch/TruffleDispatcher.java

@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2023, 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.
+ *
+ * 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 sun.nio.ch;
+
+import java.io.FileDescriptor;
+import java.io.IOException;
+
+class TruffleDispatcher extends NativeDispatcher {
+    @Override
+    int read(FileDescriptor fd, long address, int len) throws IOException {
+        return read0(fd, address, len);
+    }
+
+    @Override
+    long readv(FileDescriptor fd, long address, int len) throws IOException {
+        return readv0(fd, address, len);
+    }
+
+    @Override
+    int write(FileDescriptor fd, long address, int len) throws IOException {
+        return write0(fd, address, len);
+    }
+
+    @Override
+    long writev(FileDescriptor fd, long address, int len) throws IOException {
+        return writev0(fd, address, len);
+    }
+
+    @Override
+    void close(FileDescriptor fd) throws IOException {
+        close0(fd);
+    }
+
+    private static native int read0(FileDescriptor fd, long address, int len) throws IOException;
+
+    private static native long readv0(FileDescriptor fd, long address, int len) throws IOException;
+
+    private static native int write0(FileDescriptor fd, long address, int len) throws IOException;
+
+    private static native long writev0(FileDescriptor fd, long address, int len) throws IOException;
+
+    private static native void close0(FileDescriptor fd) throws IOException;
+
+}

espresso/src/com.oracle.truffle.espresso.io/src/sun/nio/fs/TruffleFileSystemProvider.java

@@ -52,7 +52,6 @@
  * This file must be compatible with 21+.
  */
 class TruffleFileSystemProvider extends FileSystemProvider {
-
     static {
         // ensure 'nio' is loaded. Also loads 'net' as a side-effect.
         sun.nio.ch.IOUtil.load();

espresso/src/com.oracle.truffle.espresso.io/src/sun/nio/fs/TruffleFilteredDirectoryStream.java

@@ -31,17 +31,19 @@
 import java.util.Objects;
 
 /**
- * This file must be compatible with 21+.
+ * DirectoryStream implementation by setting a host iterator and stream as hidden host reference
+ * then proxying all methods to the native world where we retrieve the host object and do the
+ * semantics of the function. Note this file must be compatible with 21+.
  */
 final class TruffleFilteredDirectoryStream implements DirectoryStream<Path> {
     private final TrufflePath truffleDir;
-    private final DirectoryStream<Object> stream;
+    private final DirectoryStream<String> stream;
     private final DirectoryStream.Filter<? super Path> filter;
 
     /**
-     * Thin wrapper for a foreign (host) {@code Iterator<Object>}, cannot have any fields.
+     * Thin wrapper for a foreign (host) {@code Iterator<String>}, cannot have any fields.
      */
-    private static final class ForeignIterator implements Iterator<Object> {
+    private static final class ForeignIterator implements Iterator<String> {
 
         private ForeignIterator() {
             // only foreign wrappers allowed
@@ -53,15 +55,15 @@ public boolean hasNext() {
         }
 
         @Override
-        public Object next() {
+        public String next() {
             return next0(this);
         }
     }
 
     /**
      * Thin wrapper for a foreign (host) DirectoryStream, cannot have any fields.
      */
-    private static final class ForeignDirectoryStream implements DirectoryStream<Object> {
+    private static final class ForeignDirectoryStream implements DirectoryStream<String> {
 
         private ForeignDirectoryStream() {
             // only foreign wrappers
@@ -73,19 +75,19 @@ public void close() throws IOException {
         }
 
         @Override
-        public Iterator<Object> iterator() {
-            return iterator0(this, ForeignIterator.class);
+        public Iterator<String> iterator() {
+            return iterator0(this);
         }
     }
 
     static DirectoryStream<Path> create(TrufflePath truffleDir, Filter<? super Path> filter) throws IOException {
         if (!Files.isDirectory(truffleDir)) {
             throw new NotDirectoryException(truffleDir.toString());
         }
-        return new TruffleFilteredDirectoryStream(truffleDir, directoryStream0(truffleDir, ForeignDirectoryStream.class), filter);
+        return new TruffleFilteredDirectoryStream(truffleDir, directoryStream0(truffleDir), filter);
     }
 
-    private TruffleFilteredDirectoryStream(TrufflePath dir, DirectoryStream<Object> stream, Filter<? super Path> filter) {
+    private TruffleFilteredDirectoryStream(TrufflePath dir, DirectoryStream<String> stream, Filter<? super Path> filter) {
         this.truffleDir = Objects.requireNonNull(dir);
         this.filter = Objects.requireNonNull(filter);
         this.stream = Objects.requireNonNull(stream);
@@ -94,7 +96,7 @@ private TruffleFilteredDirectoryStream(TrufflePath dir, DirectoryStream<Object>
 
     @Override
     public Iterator<Path> iterator() {
-        return MapFilterIterator.mapThenFilter(stream.iterator(), tf -> toTrufflePath0(tf, truffleDir.getTruffleFileSystem()),
+        return MapFilterIterator.mapThenFilter(stream.iterator(), tf -> new TrufflePath((TruffleFileSystem) truffleDir.getFileSystem(), truffleDir.resolve(tf).toString()),
                         path -> {
                             try {
                                 return filter.accept(path);
@@ -116,17 +118,15 @@ private static <T extends Throwable> RuntimeException sneakyThrow(Throwable ex)
 
     // region native methods
 
-    private static native DirectoryStream<Object> directoryStream0(TrufflePath dir, Class<ForeignDirectoryStream> directoryStreamClass) throws IOException;
+    private static native DirectoryStream<String> directoryStream0(TrufflePath dir) throws IOException;
 
-    private static native boolean hasNext0(Iterator<Object> iterator);
+    private static native boolean hasNext0(Iterator<String> iterator);
 
-    private static native Object next0(Iterator<Object> iterator);
+    private static native String next0(Iterator<String> iterator);
 
-    private static native void close0(DirectoryStream<Object> directoryStream) throws IOException;
+    private static native void close0(DirectoryStream<String> directoryStream) throws IOException;
 
-    private static native Iterator<Object> iterator0(DirectoryStream<Object> directoryStream, Class<ForeignIterator> iteratorClass);
-
-    private static native TrufflePath toTrufflePath0(Object truffleFile, TruffleFileSystem truffleFileSystem);
+    private static native Iterator<String> iterator0(DirectoryStream<String> directoryStream);
 
     // endregion native methods
 }

espresso/src/com.oracle.truffle.espresso/src/com/oracle/truffle/espresso/descriptors/EspressoSymbols.java

@@ -185,6 +185,9 @@ public static void ensureInitialized() {
         public static final Symbol<Type> sun_nio_ch_IOStatus = SYMBOLS.putType("Lsun/nio/ch/IOStatus;");
         public static final Symbol<Type> java_net_spi_InetAddressResolver$LookupPolicy = SYMBOLS.putType("Ljava/net/spi/InetAddressResolver$LookupPolicy;");
         public static final Symbol<Type> sun_nio_ch_Net = SYMBOLS.putType("Lsun/nio/ch/Net;");
+        // libnio
+        public static final Symbol<Type> sun_nio_fs_TruffleFilteredDirectoryStream$ForeignDirectoryStream = SYMBOLS.putType("Lsun/nio/fs/TruffleFilteredDirectoryStream$ForeignDirectoryStream;");
+        public static final Symbol<Type> sun_nio_fs_TruffleFilteredDirectoryStream$ForeignIterator = SYMBOLS.putType("Lsun/nio/fs/TruffleFilteredDirectoryStream$ForeignIterator;");
         // URL class loader
         public static final Symbol<Type> java_net_URLClassLoader = SYMBOLS.putType("Ljava/net/URLClassLoader;");
         public static final Symbol<Type> java_net_URL = SYMBOLS.putType("Ljava/net/URL;");