8305945: (zipfs) Opening a directory to get input stream produces incorrect exception message

Reviewed-by: naoto, cstein

Author: Lance Andersen

src/jdk.zipfs/share/classes/jdk/nio/zipfs/ZipFileSystem.java

@@ -860,7 +860,7 @@ InputStream newInputStream(byte[] path) throws IOException {
             if (e == null)
                 throw new NoSuchFileException(getString(path));
             if (e.isDir())
-                throw new FileSystemException(getString(path), "is a directory", null);
+                throw new FileSystemException(getString(path), null, "is a directory");
             return getInputStream(e);
         } finally {
             endRead();

test/jdk/jdk/nio/zipfs/ZipFSDirectoryExceptionMessageTest.java

@@ -0,0 +1,102 @@
+/*
+ * 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.
+ *
+ */
+
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+import java.nio.file.*;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipOutputStream;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+/**
+ * @test
+ * @bug 8305945
+ * @summary Validate that Zip FS provides the correct exception message when an
+ * attempt is made to obtain an InputStream from a directory entry
+ * @modules jdk.zipfs
+ * @run junit ZipFSDirectoryExceptionMessageTest
+ */
+public class ZipFSDirectoryExceptionMessageTest {
+    /**
+     * Name of Directory created within the Zip file
+     */
+    public static final String DIRECTORY_NAME = "folder/";
+    /**
+     * The expected error message
+     */
+    public static final String DIR_EXCEPTION_MESSAGE = "/folder: is a directory";
+    /**
+     * Zip file to create
+     */
+    public static final Path ZIP_FILE = Path.of("directoryExceptionTest.zip");
+
+    /**
+     * Create a Zip file which contains a single directory entry
+     * @throws IOException if an error occurs
+     */
+    @BeforeEach
+    public void setup() throws IOException {
+        var ze = new ZipEntry(DIRECTORY_NAME);
+        ze.setMethod(ZipEntry.STORED);
+        ze.setCompressedSize(0);
+        ze.setSize(0);
+        ze.setCrc(0);
+        try (ZipOutputStream zos = new ZipOutputStream(
+                Files.newOutputStream(ZIP_FILE))) {
+            zos.putNextEntry(ze);
+        }
+    }
+
+    /**
+     * Delete the Zip file used by the test
+     * @throws IOException If an error occurs
+     */
+    @AfterEach
+    public void cleanup() throws IOException {
+        Files.deleteIfExists(ZIP_FILE);
+    }
+
+    /**
+     * Validate that Zip FS returns the correct Exception message when
+     * attempting to obtain an InputStream from a path representing a directory
+     * and the FileSystemException::getOtherfile returns null
+     *
+     * @throws IOException If an error occurs
+     */
+    @Test
+    public void testException() throws IOException {
+        try (FileSystem zipfs = FileSystems.newFileSystem(ZIP_FILE)) {
+            var file = zipfs.getPath(DIRECTORY_NAME);
+            var x = assertThrows(FileSystemException.class, () -> Files.newInputStream(file));
+            // validate that other file should be null
+            assertNull(x.getOtherFile());
+            assertEquals(DIR_EXCEPTION_MESSAGE, x.getMessage());
+        }
+    }
+}