8322166: Files.isReadable/isWritable/isExecutable expensive when file does not exist

Reviewed-by: alanb

src/java.base/share/classes/java/nio/file/Files.java

@@ -80,6 +80,7 @@ import java.util.stream.StreamSupport;
 import jdk.internal.util.ArraysSupport;
 import sun.nio.ch.FileChannelImpl;
 import sun.nio.cs.UTF_8;
+import sun.nio.fs.AbstractFileSystemProvider;
 
 /**
  * This class consists exclusively of static methods that operate on files,
@@ -2609,7 +2610,11 @@ public final class Files {
      *          is invoked to check read access to the file.
      */
     public static boolean isReadable(Path path) {
-        return isAccessible(path, AccessMode.READ);
+        FileSystemProvider provider = provider(path);
+        if (provider instanceof AbstractFileSystemProvider afsp)
+            return afsp.isReadable(path);
+        else
+            return isAccessible(path, AccessMode.READ);
     }
 
     /**
@@ -2640,7 +2645,11 @@ public final class Files {
      *          is invoked to check write access to the file.
      */
     public static boolean isWritable(Path path) {
-        return isAccessible(path, AccessMode.WRITE);
+        FileSystemProvider provider = provider(path);
+        if (provider instanceof AbstractFileSystemProvider afsp)
+            return afsp.isWritable(path);
+        else
+            return isAccessible(path, AccessMode.WRITE);
     }
 
     /**
@@ -2675,7 +2684,11 @@ public final class Files {
      *          checkExec} is invoked to check execute access to the file.
      */
     public static boolean isExecutable(Path path) {
-        return isAccessible(path, AccessMode.EXECUTE);
+        FileSystemProvider provider = provider(path);
+        if (provider instanceof AbstractFileSystemProvider afsp)
+            return afsp.isExecutable(path);
+        else
+            return isAccessible(path, AccessMode.EXECUTE);
     }
 
     // -- Recursive operations --

src/java.base/share/classes/sun/nio/fs/AbstractFileSystemProvider.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 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
@@ -25,8 +25,9 @@
 
 package sun.nio.fs;
 
-import java.nio.file.Path;
+import java.nio.file.AccessMode;
 import java.nio.file.LinkOption;
+import java.nio.file.Path;
 import java.nio.file.spi.FileSystemProvider;
 import java.io.IOException;
 import java.util.Map;
@@ -115,4 +116,40 @@ public abstract class AbstractFileSystemProvider extends FileSystemProvider {
      * If path is empty, then an empty byte[] is returned.
      */
     public abstract byte[] getSunPathForSocketFile(Path path);
+
+    /**
+     * Tests whether a file is readable.
+     */
+    public boolean isReadable(Path path) {
+        try {
+            checkAccess(path, AccessMode.READ);
+        } catch (IOException e) {
+            return false;
+        }
+        return true;
+    }
+
+    /**
+     * Tests whether a file is writable.
+     */
+    public boolean isWritable(Path path) {
+        try {
+            checkAccess(path, AccessMode.WRITE);
+        } catch (IOException e) {
+            return false;
+        }
+        return true;
+    }
+
+    /**
+     * Tests whether a file is executable.
+     */
+    public boolean isExecutable(Path path) {
+        try {
+            checkAccess(path, AccessMode.EXECUTE);
+        } catch (IOException e) {
+            return false;
+        }
+        return true;
+    }
 }