GH-9211: Fix SmbSession.get()

Fixes: #9211

The `AbstractRemoteFileOutboundGateway.get()` uses `Session.list()` for the provided remote file name.
The `SmbSession` does not support listing for a single file.

* Add logic into `SmbSession.list()` similar to `SftpSession.list()` to list a single remote file
on the provided path

(cherry picked from commit 91de12c786)

spring-integration-smb/src/main/java/org/springframework/integration/smb/session/SmbSession.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,6 +23,7 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.net.URL;
+import java.nio.file.FileSystems;
 import java.util.Arrays;
 
 import jcifs.smb.SmbException;
@@ -39,10 +40,10 @@ import org.springframework.util.StringUtils;
  * Implementation of the {@link Session} interface for Server Message Block (SMB)
  * also known as Common Internet File System (CIFS). The Samba project set out to
  * create non-Windows implementations of SMB. Often Samba is thus used synonymously to SMB.
- *
+ * <p>
  * SMB is an application-layer network protocol that manages shared access to files, printers
  * and other networked resources.
- *
+ * <p>
  * See <a href="https://en.wikipedia.org/wiki/Server_Message_Block">Server Message Block</a>
  * for more details.
  *
@@ -60,7 +61,7 @@ public class SmbSession implements Session<SmbFile> {
 
 	private static final LogAccessor logger = new LogAccessor(SmbSession.class);
 
-	private static final String FILE_SEPARATOR = System.getProperty("file.separator");
+	private static final String FILE_SEPARATOR = FileSystems.getDefault().getSeparator();
 
 	private static final String SMB_FILE_SEPARATOR = "/";
 
@@ -120,31 +121,42 @@ public class SmbSession implements Session<SmbFile> {
 	/**
 	 * Return the contents of the specified SMB resource as an array of SmbFile objects.
 	 * In case the remote resource does not exist, an empty array is returned.
-	 * @param _path path to a remote directory
+	 * @param remotePath path to a remote directory or remote file path
 	 * @return array of SmbFile objects
 	 * @throws IOException on error conditions returned by a CIFS server or if the remote resource is not a directory.
 	 */
 	@Override
-	public SmbFile[] list(String _path) throws IOException {
-		try {
-			SmbFile smbDir = createSmbDirectoryObject(_path);
-			if (!smbDir.exists()) {
-				logger.warn(() -> "Remote directory [" + _path + "] does not exist. Cannot list resources.");
-				return new SmbFile[0];
+	public SmbFile[] list(String remotePath) throws IOException {
+		SmbFile[] files;
+		int lastIndex = StringUtils.hasText(remotePath) ? remotePath.lastIndexOf('/') : 0;
+		String remoteFileName = lastIndex > 0 ? remotePath.substring(lastIndex + 1) : null;
+		if (StringUtils.hasText(remoteFileName)) {
+			SmbFile remoteFile = createSmbFileObject(remotePath);
+			if (!remoteFile.isFile()) {
+				throw new IOException("[" + remotePath + "] is not a file.");
 			}
-			else if (!smbDir.isDirectory()) {
-				throw new IOException("[" + _path + "] is not a directory. Cannot list resources.");
+			files = new SmbFile[] {remoteFile};
+		}
+		else {
+			try {
+				SmbFile smbDir = createSmbDirectoryObject(remotePath);
+				if (!smbDir.exists()) {
+					logger.warn(() -> "Remote directory [" + remotePath + "] does not exist. Cannot list resources.");
+					return new SmbFile[0];
+				}
+				else if (!smbDir.isDirectory()) {
+					throw new IOException("[" + remotePath + "] is not a directory. Cannot list resources.");
+				}
+
+				files = smbDir.listFiles();
+			}
+			catch (SmbException _ex) {
+				throw new IOException("Failed to list in [" + remotePath + "].", _ex);
 			}
-
-			SmbFile[] files = smbDir.listFiles();
-
-			logListedFiles(_path, files);
-
-			return files;
-		}
-		catch (SmbException _ex) {
-			throw new IOException("Failed to list in [" + _path + "].", _ex);
 		}
+		logListedFiles(remotePath, files);
+
+		return files;
 	}
 
 	/**

spring-integration-smb/src/test/java/org/springframework/integration/smb/dsl/SmbTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2022-2023 the original author or authors.
+ * Copyright 2022-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -164,7 +164,7 @@ public class SmbTests extends SmbTestSupport {
 	}
 
 	@Test
-	public void testSmbOutboundFlow() {
+	public void testSmbOutboundFlow() throws SmbException {
 		IntegrationFlow flow = f -> f
 				.handle(Smb.outboundAdapter(sessionFactory(), FileExistsMode.REPLACE)
 						.useTemporaryFileName(false)
@@ -181,18 +181,13 @@ public class SmbTests extends SmbTestSupport {
 		SmbFile[] files = template.execute(session ->
 				session.list(getTargetRemoteDirectory().getName()));
 		assertThat(files).hasSize(1);
-		try {
-			assertThat(files[0].length()).isEqualTo(3);
-		}
-		catch (SmbException se) {
-			se.printStackTrace();
-		}
+		assertThat(files[0].length()).isEqualTo(3);
 
 		registration.destroy();
 	}
 
 	@Test
-	public void testSmbOutboundFlowWithSmbRemoteTemplate() {
+	public void testSmbOutboundFlowWithSmbRemoteTemplate() throws SmbException {
 		SmbRemoteFileTemplate smbTemplate = new SmbRemoteFileTemplate(sessionFactory());
 		IntegrationFlow flow = f -> f
 				.handle(Smb.outboundAdapter(smbTemplate)
@@ -209,18 +204,13 @@ public class SmbTests extends SmbTestSupport {
 		SmbFile[] files = smbTemplate.execute(session ->
 				session.list(getTargetRemoteDirectory().getName()));
 		assertThat(files).hasSize(1);
-		try {
-			assertThat(files[0].length()).isEqualTo(3);
-		}
-		catch (SmbException se) {
-			se.printStackTrace();
-		}
+		assertThat(files[0].length()).isEqualTo(3);
 
 		registration.destroy();
 	}
 
 	@Test
-	public void testSmbOutboundFlowWithSmbRemoteTemplateAndMode() {
+	public void testSmbOutboundFlowWithSmbRemoteTemplateAndMode() throws SmbException {
 		SmbRemoteFileTemplate smbTemplate = new SmbRemoteFileTemplate(sessionFactory());
 		IntegrationFlow flow = f -> f
 				.handle(Smb.outboundAdapter(smbTemplate, FileExistsMode.APPEND)
@@ -242,18 +232,33 @@ public class SmbTests extends SmbTestSupport {
 		SmbFile[] files = smbTemplate.execute(session ->
 				session.list(getTargetRemoteDirectory().getName()));
 		assertThat(files).hasSize(1);
-		try {
-			assertThat(files[0].length()).isEqualTo(9);
-		}
-		catch (SmbException se) {
-			se.printStackTrace();
-		}
+		assertThat(files[0].length()).isEqualTo(9);
 
 		registration.destroy();
 	}
 
 	@Test
 	public void testSmbGetFlow() {
+		QueueChannel out = new QueueChannel();
+		IntegrationFlow flow = f -> f
+				.handle(
+						Smb.outboundGateway(sessionFactory(), AbstractRemoteFileOutboundGateway.Command.GET, "payload")
+								.localDirectoryExpression("'" + getTargetLocalDirectoryName() + "'"))
+				.channel(out);
+		IntegrationFlowRegistration registration = this.flowContext.registration(flow).register();
+		String fileName = "smbSource/subSmbSource/subSmbSource2.txt";
+		registration.getInputChannel().send(new GenericMessage<>(fileName));
+		Message<?> result = out.receive(10_000);
+		assertThat(result).isNotNull();
+
+		File sfis = (File) result.getPayload();
+		assertThat(sfis).hasFileName("subSmbSource2.txt");
+
+		registration.destroy();
+	}
+
+	@Test
+	public void testSmbGetStreamFlow() throws IOException {
 		QueueChannel out = new QueueChannel();
 		IntegrationFlow flow = f -> f
 				.handle(
@@ -271,14 +276,10 @@ public class SmbTests extends SmbTestSupport {
 		Message<?> result = out.receive(10_000);
 		assertThat(result).isNotNull();
 
-		SmbFileInputStream sfis = (SmbFileInputStream) result.getPayload();
-		assertThat(sfis).isNotNull();
+		try (SmbFileInputStream sfis = (SmbFileInputStream) result.getPayload()) {
+			assertThat(sfis).isNotNull();
+		}
 
-		try {
-			sfis.close();
-		}
-		catch (IOException ioe) {
-		}
 		registration.destroy();
 	}