8364277: (fs) BasicFileAttributes.isDirectory and isOther return true for NTFS directory junctions when links not followed

Reviewed-by: alanb

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2025, 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
@@ -72,8 +72,9 @@ class WindowsConstants {
     public static final int BACKUP_SPARSE_BLOCK             = 0x00000009;
 
     // reparse point/symbolic link related constants
-    public static final int IO_REPARSE_TAG_SYMLINK              = 0xA000000C;
     public static final int IO_REPARSE_TAG_AF_UNIX              = 0x80000023;
+    public static final int IO_REPARSE_TAG_MOUNT_POINT          = 0xA0000003;
+    public static final int IO_REPARSE_TAG_SYMLINK              = 0xA000000C;
     public static final int MAXIMUM_REPARSE_DATA_BUFFER_SIZE    = 16 * 1024;
     public static final int SYMBOLIC_LINK_FLAG_DIRECTORY        = 0x1;
     public static final int SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE = 0x2;

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2025, 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
@@ -412,6 +412,10 @@ class WindowsFileAttributes
         return isSymbolicLink() && ((fileAttrs & FILE_ATTRIBUTE_DIRECTORY) != 0);
     }
 
+    boolean isDirectoryJunction() {
+        return reparseTag == IO_REPARSE_TAG_MOUNT_POINT;
+    }
+
     @Override
     public boolean isSymbolicLink() {
         return reparseTag == IO_REPARSE_TAG_SYMLINK;
@@ -423,10 +427,8 @@ class WindowsFileAttributes
 
     @Override
     public boolean isDirectory() {
-        // ignore FILE_ATTRIBUTE_DIRECTORY attribute if file is a sym link
+        return ((fileAttrs & FILE_ATTRIBUTE_DIRECTORY) != 0 &&
-        if (isSymbolicLink())
+                (fileAttrs & FILE_ATTRIBUTE_REPARSE_POINT) == 0);
-            return false;
-        return ((fileAttrs & FILE_ATTRIBUTE_DIRECTORY) != 0);
     }
 
     @Override

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

@@ -243,7 +243,8 @@ class WindowsFileSystemProvider
         try {
              // need to know if file is a directory or junction
              attrs = WindowsFileAttributes.get(file, false);
-             if (attrs.isDirectory() || attrs.isDirectoryLink()) {
+             if (attrs.isDirectory() || attrs.isDirectoryLink() ||
+                 attrs.isDirectoryJunction()) {
                 RemoveDirectory(file.getPathForWin32Calls());
              } else {
                 DeleteFile(file.getPathForWin32Calls());

test/jdk/java/nio/file/attribute/BasicFileAttributeView/Basic.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2025, 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
@@ -22,9 +22,12 @@
  */
 
 /* @test
- * @bug 4313887 6838333
+ * @bug 4313887 6838333 8364277
  * @summary Unit test for java.nio.file.attribute.BasicFileAttributeView
- * @library ../..
+ * @library ../.. /test/lib
+ * @build jdk.test.lib.Platform
+ *        jdk.test.lib.util.FileUtils
+ * @run main/othervm --enable-native-access=ALL-UNNAMED Basic
  */
 
 import java.nio.file.*;
@@ -33,6 +36,9 @@ import java.util.*;
 import java.util.concurrent.TimeUnit;
 import java.io.*;
 
+import jdk.test.lib.Platform;
+import jdk.test.lib.util.FileUtils;
+
 public class Basic {
 
     static void check(boolean okay, String msg) {
@@ -97,6 +103,17 @@ public class Basic {
         check(!attrs.isOther(), "is not other");
     }
 
+    static void checkAttributesOfJunction(Path junction)
+        throws IOException
+    {
+        BasicFileAttributes attrs =
+            Files.readAttributes(junction, BasicFileAttributes.class, LinkOption.NOFOLLOW_LINKS);
+        check(!attrs.isSymbolicLink(), "is a link");
+        check(!attrs.isDirectory(), "is a directory");
+        check(!attrs.isRegularFile(), "is not a regular file");
+        check(attrs.isOther(), "is other");
+    }
+
     static void attributeReadWriteTests(Path dir)
         throws IOException
     {
@@ -114,12 +131,18 @@ public class Basic {
         Path link = dir.resolve("link");
         try {
             Files.createSymbolicLink(link, file);
-        } catch (UnsupportedOperationException x) {
+            checkAttributesOfLink(link);
-            return;
+        } catch (IOException | UnsupportedOperationException x) {
-        } catch (IOException x) {
+            if (!Platform.isWindows())
                 return;
         }
-        checkAttributesOfLink(link);
+
+        // NTFS junctions are Windows-only
+        if (Platform.isWindows()) {
+            Path junction = dir.resolve("junction");
+            FileUtils.createWinDirectoryJunction(junction, dir);
+            checkAttributesOfJunction(junction);
+        }
     }
 
     public static void main(String[] args) throws IOException {

test/lib/jdk/test/lib/util/FileUtils.java

@@ -24,6 +24,7 @@
 package jdk.test.lib.util;
 
 import java.io.BufferedReader;
+import java.io.File;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.io.PrintStream;
@@ -33,6 +34,7 @@ import java.lang.management.ManagementFactory;
 import java.nio.file.DirectoryNotEmptyException;
 import java.nio.file.FileVisitResult;
 import java.nio.file.Files;
+import java.nio.file.LinkOption;
 import java.nio.file.NoSuchFileException;
 import java.nio.file.Path;
 import java.nio.file.SimpleFileVisitor;
@@ -64,6 +66,14 @@ public final class FileUtils {
     private static final int MAX_RETRY_DELETE_TIMES = IS_WINDOWS ? 15 : 0;
     private static volatile boolean nativeLibLoaded;
 
+    @SuppressWarnings("restricted")
+    private static void loadNativeLib() {
+        if (!nativeLibLoaded) {
+            System.loadLibrary("FileUtils");
+            nativeLibLoaded = true;
+        }
+    }
+
     /**
      * Deletes a file, retrying if necessary.
      *
@@ -392,14 +402,10 @@ public final class FileUtils {
     }
 
     // Return the current process handle count
-    @SuppressWarnings("restricted")
     public static long getProcessHandleCount() {
         if (IS_WINDOWS) {
-            if (!nativeLibLoaded) {
+            loadNativeLib();
-                System.loadLibrary("FileUtils");
+            return getWinProcessHandleCount0();
-                nativeLibLoaded = true;
-            }
-            return getWinProcessHandleCount();
         } else {
             return ((UnixOperatingSystemMXBean)ManagementFactory.getOperatingSystemMXBean()).getOpenFileDescriptorCount();
         }
@@ -443,7 +449,23 @@ public final class FileUtils {
         Files.write(path, lines);
     }
 
-    private static native long getWinProcessHandleCount();
+    // Create a directory junction with the specified target
+    public static boolean createWinDirectoryJunction(Path junction, Path target)
+        throws IOException
+    {
+        assert IS_WINDOWS;
+
+        // Convert "target" to its real path
+        target = target.toRealPath();
+
+        // Create a directory junction
+        loadNativeLib();
+        return createWinDirectoryJunction0(junction.toString(), target.toString());
+    }
+
+    private static native long getWinProcessHandleCount0();
+    private static native boolean createWinDirectoryJunction0(String junction,
+        String target) throws IOException;
 
     // Possible command locations and arguments
     static String[][] lsCommands = new String[][] {

test/lib/jdk/test/lib/util/libFileUtils.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2025, 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
@@ -27,9 +27,49 @@
 #ifdef _WIN32
 
 #include "jni.h"
+#include "jni_util.h"
+#include <string.h>
 #include <windows.h>
+#include <fileapi.h>
+#include <handleapi.h>
+#include <ioapiset.h>
+#include <winioctl.h>
+#include <errhandlingapi.h>
 
-JNIEXPORT jlong JNICALL Java_jdk_test_lib_util_FileUtils_getWinProcessHandleCount(JNIEnv *env)
+// Based on Microsoft documentation
+#define MAX_REPARSE_BUFFER_SIZE 16384
+
+// Unavailable in standard header files:
+// copied from Microsoft documentation
+typedef struct _REPARSE_DATA_BUFFER {
+    ULONG  ReparseTag;
+    USHORT ReparseDataLength;
+    USHORT Reserved;
+    union {
+        struct {
+            USHORT SubstituteNameOffset;
+            USHORT SubstituteNameLength;
+            USHORT PrintNameOffset;
+            USHORT PrintNameLength;
+            ULONG  Flags;
+            WCHAR  PathBuffer[1];
+        } SymbolicLinkReparseBuffer;
+        struct {
+            USHORT SubstituteNameOffset;
+            USHORT SubstituteNameLength;
+            USHORT PrintNameOffset;
+            USHORT PrintNameLength;
+            WCHAR  PathBuffer[1];
+        } MountPointReparseBuffer;
+        struct {
+            UCHAR DataBuffer[1];
+        } GenericReparseBuffer;
+    } DUMMYUNIONNAME;
+} REPARSE_DATA_BUFFER, * PREPARSE_DATA_BUFFER;
+
+JNIEXPORT jlong JNICALL
+Java_jdk_test_lib_util_FileUtils_getWinProcessHandleCount0
+    (JNIEnv* env)
 {
     DWORD handleCount;
     HANDLE handle = GetCurrentProcess();
@@ -40,4 +80,118 @@ JNIEXPORT jlong JNICALL Java_jdk_test_lib_util_FileUtils_getWinProcessHandleCoun
     }
 }
 
+void throwIOExceptionWithLastError(JNIEnv* env) {
+#define BUFSIZE 256
+    DWORD errval;
+    WCHAR buf[BUFSIZE];
+
+    if ((errval = GetLastError()) != 0) {
+        jsize n = FormatMessageW(
+            FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
+            NULL, errval, 0, buf, BUFSIZE, NULL);
+
+        jclass ioExceptionClass = (*env)->FindClass(env, "java/io/IOException");
+        (*env)->ThrowNew(env, ioExceptionClass, (const char*) buf);
+    }
+}
+
+JNIEXPORT jboolean JNICALL
+Java_jdk_test_lib_util_FileUtils_createWinDirectoryJunction0
+    (JNIEnv* env, jclass unused, jstring sjunction, jstring starget)
+{
+    BOOL error = FALSE;
+
+    const jshort bpc = sizeof(wchar_t); // bytes per character
+    HANDLE hJunction = INVALID_HANDLE_VALUE;
+
+    const jchar* junction = (*env)->GetStringChars(env, sjunction, NULL);
+    const jchar* target   = (*env)->GetStringChars(env, starget, NULL);
+    if (junction == NULL || target == NULL) {
+        jclass npeClass = (*env)->FindClass(env, "java/lang/NullPointerException");
+        (*env)->ThrowNew(env, npeClass, NULL);
+        error = TRUE;
+    }
+
+    USHORT wlen = (USHORT)0;
+    USHORT blen = (USHORT)0;
+    void* lpInBuffer = NULL;
+    if (!error) {
+        wlen = (USHORT)wcslen(target);
+        blen = (USHORT)(wlen * sizeof(wchar_t));
+        lpInBuffer = calloc(MAX_REPARSE_BUFFER_SIZE, sizeof(char));
+        if (lpInBuffer == NULL) {
+            jclass oomeClass = (*env)->FindClass(env, "java/lang/OutOfMemoryError");
+            (*env)->ThrowNew(env, oomeClass, NULL);
+            error = TRUE;
+        }
+    }
+
+    if (!error) {
+        if (CreateDirectoryW(junction, NULL) == 0) {
+            throwIOExceptionWithLastError(env);
+            error = TRUE;
+        }
+    }
+
+    if (!error) {
+        hJunction = CreateFileW(junction, GENERIC_READ | GENERIC_WRITE,
+                                FILE_SHARE_READ | FILE_SHARE_WRITE, NULL,
+                                OPEN_EXISTING,
+                                FILE_FLAG_OPEN_REPARSE_POINT
+                                | FILE_FLAG_BACKUP_SEMANTICS, NULL);
+        if (hJunction == INVALID_HANDLE_VALUE) {
+            throwIOExceptionWithLastError(env);
+            error = TRUE;
+        }
+    }
+
+    if (!error) {
+        PREPARSE_DATA_BUFFER reparseBuffer = (PREPARSE_DATA_BUFFER)lpInBuffer;
+        reparseBuffer->ReparseTag = IO_REPARSE_TAG_MOUNT_POINT;
+        reparseBuffer->Reserved = 0;
+        WCHAR* prefix = L"\\??\\";
+        USHORT prefixLength = (USHORT)(bpc * wcslen(prefix));
+        reparseBuffer->MountPointReparseBuffer.SubstituteNameOffset = 0;
+        reparseBuffer->MountPointReparseBuffer.SubstituteNameLength =
+            prefixLength + blen;
+        reparseBuffer->MountPointReparseBuffer.PrintNameOffset =
+            prefixLength + blen + sizeof(WCHAR);
+        reparseBuffer->MountPointReparseBuffer.PrintNameLength = blen;
+        memcpy(&reparseBuffer->MountPointReparseBuffer.PathBuffer,
+               prefix, prefixLength);
+        memcpy(&reparseBuffer->MountPointReparseBuffer.PathBuffer[prefixLength/bpc],
+               target, blen);
+        memcpy(&reparseBuffer->MountPointReparseBuffer.PathBuffer[prefixLength/bpc + blen/bpc + 1],
+               target, blen);
+        reparseBuffer->ReparseDataLength =
+            (USHORT)(sizeof(reparseBuffer->MountPointReparseBuffer) +
+                     prefixLength + bpc*blen + bpc);
+        DWORD nInBufferSize = FIELD_OFFSET(REPARSE_DATA_BUFFER,
+            MountPointReparseBuffer) + reparseBuffer->ReparseDataLength;
+        BOOL result = DeviceIoControl(hJunction, FSCTL_SET_REPARSE_POINT,
+                                      lpInBuffer, nInBufferSize,
+                                      NULL, 0, NULL, NULL);
+        if (result == 0) {
+            throwIOExceptionWithLastError(env);
+            error = TRUE;
+        }
+    }
+
+    if (junction != NULL) {
+        (*env)->ReleaseStringChars(env, sjunction, junction);
+        if (target != NULL) {
+            (*env)->ReleaseStringChars(env, starget, target);
+            if (lpInBuffer != NULL) {
+                free(lpInBuffer);
+                if (hJunction != INVALID_HANDLE_VALUE) {
+                    // Ignore any error in CloseHandle
+                    CloseHandle(hJunction);
+                }
+            }
+        }
+    }
+
+    return error ? JNI_FALSE : JNI_TRUE;
+}
+
 #endif  /*  _WIN32 */