8254876: (fs) NullPointerException not thrown when first argument to Path.of or Paths.get is null

Reviewed-by: rriggs, alanb

Author: Brian Burkhalter

src/java.base/unix/classes/sun/nio/fs/UnixFileSystem.java

@@ -257,6 +257,7 @@ public Iterator<FileStore> iterator() {
 
     @Override
     public final Path getPath(String first, String... more) {
+        Objects.requireNonNull(first);
         String path;
         if (more.length == 0) {
             path = first;

src/java.base/windows/classes/sun/nio/fs/WindowsFileSystem.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 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
@@ -211,6 +211,7 @@ public Set<String> supportedFileAttributeViews() {
 
     @Override
     public final Path getPath(String first, String... more) {
+        Objects.requireNonNull(first);
         String path;
         if (more.length == 0) {
             path = first;

test/jdk/java/nio/file/Path/PathOps.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 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
@@ -22,7 +22,7 @@
  */
 
 /* @test
- * @bug 4313887 6838333 6925932 7006126 8037945 8072495 8140449
+ * @bug 4313887 6838333 6925932 7006126 8037945 8072495 8140449 8254876
  * @summary Unit test for java.nio.file.Path path operations
  */
 
@@ -2042,6 +2042,18 @@ static void doUnixTests() {
     static void npes() {
         header("NullPointerException");
 
+        try {
+            Path.of(null, "foo");
+            throw new RuntimeException("NullPointerException not thrown");
+        } catch (NullPointerException npe) {
+        }
+
+        try {
+            Path.of("foo", null);
+            throw new RuntimeException("NullPointerException not thrown");
+        } catch (NullPointerException npe) {
+        }
+
         Path path = FileSystems.getDefault().getPath("foo");
 
         try {