From 6c98dd80096fbee36472d2aeb16f38e2d347b11a Mon Sep 17 00:00:00 2001
From: Rob Spoor <rob@icemanx.nl>
Date: Wed, 31 Jul 2019 15:34:12 +0200
Subject: [PATCH] Check file attributes if . is not part of a directory listing

---
 .../filesystems/sftp/SFTPFileSystem.java      |  7 +++-
 .../sftp/AbstractSFTPFileSystemTest.java      |  7 +++-
 .../SFTPFileSystemWithoutSystemDirsTest.java  | 32 +++++++++++++++++++
 .../sftp/server/FixedSftpSubsystem.java       | 29 +++++++++++++++++
 4 files changed, 73 insertions(+), 2 deletions(-)
 create mode 100644 src/test/java/com/github/robtimus/filesystems/sftp/SFTPFileSystemWithoutSystemDirsTest.java

diff --git a/src/main/java/com/github/robtimus/filesystems/sftp/SFTPFileSystem.java b/src/main/java/com/github/robtimus/filesystems/sftp/SFTPFileSystem.java
index 78a3ac2..fa61d51 100644
--- a/src/main/java/com/github/robtimus/filesystems/sftp/SFTPFileSystem.java
+++ b/src/main/java/com/github/robtimus/filesystems/sftp/SFTPFileSystem.java
@@ -338,7 +338,12 @@ DirectoryStream<Path> newDirectoryStream(final SFTPPath path, Filter<? super Pat
             }
 
             if (!isDirectory) {
-                throw new NotDirectoryException(path.path());
+                // https://github.com/robtimus/sftp-fs/issues/4: don't fail immediately but check the attributes
+                // Follow links to ensure the directory attribute can be read correctly
+                SftpATTRS attributes = channel.readAttributes(path.path(), true);
+                if (!attributes.isDir()) {
+                    throw new NotDirectoryException(path.path());
+                }
             }
             return new SFTPPathDirectoryStream(path, entries, filter);
         }
diff --git a/src/test/java/com/github/robtimus/filesystems/sftp/AbstractSFTPFileSystemTest.java b/src/test/java/com/github/robtimus/filesystems/sftp/AbstractSFTPFileSystemTest.java
index a1a13c1..74688e5 100644
--- a/src/test/java/com/github/robtimus/filesystems/sftp/AbstractSFTPFileSystemTest.java
+++ b/src/test/java/com/github/robtimus/filesystems/sftp/AbstractSFTPFileSystemTest.java
@@ -49,6 +49,7 @@
 import org.apache.sshd.server.SshServer;
 import org.apache.sshd.server.auth.password.PasswordAuthenticator;
 import org.apache.sshd.server.session.ServerSession;
+import org.apache.sshd.server.subsystem.sftp.SftpSubsystemFactory;
 import org.junit.After;
 import org.junit.AfterClass;
 import org.junit.Before;
@@ -72,6 +73,10 @@ public abstract class AbstractSFTPFileSystemTest {
 
     @BeforeClass
     public static void setupClass() throws NoSuchAlgorithmException, IOException {
+        setupClass(new FixedSftpSubsystem.Factory());
+    }
+
+    protected static void setupClass(SftpSubsystemFactory subSystemFactory) throws NoSuchAlgorithmException, IOException {
         KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA");
         KeyPair keyPair = generator.generateKeyPair();
 
@@ -86,7 +91,7 @@ public boolean authenticate(String username, String password, ServerSession sess
                 return USERNAME.equals(username) && PASSWORD.equals(password);
             }
         });
-        sshServer.setSubsystemFactories(Arrays.<NamedFactory<Command>>asList(new FixedSftpSubsystem.Factory()));
+        sshServer.setSubsystemFactories(Arrays.<NamedFactory<Command>>asList(subSystemFactory));
 
         rootPath = Files.createTempDirectory("sftp-fs");
         defaultDir = rootPath.resolve("home");
diff --git a/src/test/java/com/github/robtimus/filesystems/sftp/SFTPFileSystemWithoutSystemDirsTest.java b/src/test/java/com/github/robtimus/filesystems/sftp/SFTPFileSystemWithoutSystemDirsTest.java
new file mode 100644
index 0000000..42acb75
--- /dev/null
+++ b/src/test/java/com/github/robtimus/filesystems/sftp/SFTPFileSystemWithoutSystemDirsTest.java
@@ -0,0 +1,32 @@
+/*
+ * SFTPFileSystemWithoutSystemDirsTest.java
+ * Copyright 2019 Rob Spoor
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.github.robtimus.filesystems.sftp;
+
+import java.io.IOException;
+import java.security.NoSuchAlgorithmException;
+import org.junit.BeforeClass;
+import com.github.robtimus.filesystems.sftp.server.FixedSftpSubsystem;
+
+@SuppressWarnings("javadoc")
+public class SFTPFileSystemWithoutSystemDirsTest extends SFTPFileSystemTest {
+
+    @BeforeClass
+    public static void setupClass() throws NoSuchAlgorithmException, IOException {
+        setupClass(new FixedSftpSubsystem.FactoryWithoutSystemDirs());
+    }
+}
diff --git a/src/test/java/com/github/robtimus/filesystems/sftp/server/FixedSftpSubsystem.java b/src/test/java/com/github/robtimus/filesystems/sftp/server/FixedSftpSubsystem.java
index eb1b64a..c3f340b 100644
--- a/src/test/java/com/github/robtimus/filesystems/sftp/server/FixedSftpSubsystem.java
+++ b/src/test/java/com/github/robtimus/filesystems/sftp/server/FixedSftpSubsystem.java
@@ -25,6 +25,9 @@
 import org.apache.sshd.common.util.GenericUtils;
 import org.apache.sshd.common.util.io.IoUtils;
 import org.apache.sshd.server.Command;
+import org.apache.sshd.server.session.ServerSession;
+import org.apache.sshd.server.subsystem.sftp.DirectoryHandle;
+import org.apache.sshd.server.subsystem.sftp.Handle;
 import org.apache.sshd.server.subsystem.sftp.SftpEventListener;
 import org.apache.sshd.server.subsystem.sftp.SftpSubsystem;
 import org.apache.sshd.server.subsystem.sftp.SftpSubsystemFactory;
@@ -63,4 +66,30 @@ public Command create() {
             return subsystem;
         }
     }
+
+    public static final class FactoryWithoutSystemDirs extends SftpSubsystemFactory {
+
+        @Override
+        public Command create() {
+            SftpSubsystem subsystem = new FixedSftpSubsystem(getExecutorService(), isShutdownOnExit(), getUnsupportedAttributePolicy());
+            Collection<? extends SftpEventListener> listeners = getRegisteredListeners();
+            if (GenericUtils.size(listeners) > 0) {
+                for (SftpEventListener l : listeners) {
+                    subsystem.addSftpEventListener(l);
+                }
+            }
+            subsystem.addSftpEventListener(new SftpEventListener() {
+                @Override
+                public void open(ServerSession session, String remoteHandle, Handle localHandle) throws IOException {
+                    if (localHandle instanceof DirectoryHandle) {
+                        DirectoryHandle directoryHandle = (DirectoryHandle) localHandle;
+                        directoryHandle.markDotSent();
+                        directoryHandle.markDotDotSent();
+                    }
+                }
+            });
+
+            return subsystem;
+        }
+    }
 }