INT-4117: File Outbound Set File Permissions

JIRA: https://jira.spring.io/browse/INT-4117

Add an option to set file permissions on the `FileWritingMessageHandler` when the file system supports it.

Polishing - PR Comments; more robust file system detection.

Add DSL support and fix NPE with missing timestamp header.

Fix javadoc

Fix javadoc

Some polishing:

* Add `chmod >= 0` assertion
* Make some assertion with string concatenation as `Supplier`-based to
deffer that string concatenation

spring-integration-file/src/main/java/org/springframework/integration/file/FileWritingMessageHandler.java

@@ -29,10 +29,14 @@ import java.io.OutputStreamWriter;
 import java.nio.charset.Charset;
 import java.nio.file.Files;
 import java.nio.file.StandardCopyOption;
+import java.nio.file.attribute.PosixFilePermission;
+import java.util.BitSet;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Map.Entry;
+import java.util.Set;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.locks.Lock;
 import java.util.regex.Matcher;
@@ -48,6 +52,7 @@ import org.springframework.expression.common.LiteralExpression;
 import org.springframework.expression.spel.support.StandardEvaluationContext;
 import org.springframework.integration.expression.ExpressionUtils;
 import org.springframework.integration.file.support.FileExistsMode;
+import org.springframework.integration.file.support.FileUtils;
 import org.springframework.integration.handler.AbstractReplyProducingMessageHandler;
 import org.springframework.integration.handler.MessageTriggerAction;
 import org.springframework.integration.support.locks.DefaultLockRegistry;
@@ -152,6 +157,8 @@ public class FileWritingMessageHandler extends AbstractReplyProducingMessageHand
 
 	private volatile boolean preserveTimestamp;
 
+	private Set<PosixFilePermission> permissions;
+
 	/**
 	 * Constructor which sets the {@link #destinationDirectoryExpression} using
 	 * a {@link LiteralExpression}.
@@ -367,6 +374,75 @@ public class FileWritingMessageHandler extends AbstractReplyProducingMessageHand
 		this.preserveTimestamp = preserveTimestamp;
 	}
 
+	/**
+	 * String setter for Spring XML convenience.
+	 * @param chmod permissions as an octal string e.g "600";
+	 * @see #setChmod(int)
+	 * @since 5.0
+	 */
+	public void setChmodOctal(String chmod) {
+		Assert.notNull(chmod, "'chmod' cannot be null");
+		setChmod(Integer.parseInt(chmod, 8));
+	}
+
+	/**
+	 * Set the file permissions after uploading, e.g. 0600 for
+	 * owner read/write. Only applies to file systems that support posix
+	 * file permissions.
+	 * @param chmod the permissions.
+	 * @throws IllegalArgumentException if the value is higher than 0777.
+	 * @since 5.0
+	 */
+	public void setChmod(int chmod) {
+		Assert.isTrue(chmod >= 0 && chmod <= 0777, "'chmod' must be between 0 and 0777 (octal)");
+		if (!FileUtils.IS_POSIX) {
+			this.logger.error("'chmod' setting ignored - the file system does not support Posix attributes");
+			return;
+		}
+		/*
+		 * Bitset.valueOf(byte[]) takes a little-endian array of bytes to create a BitSet.
+		 * Since we are interested in 9 bits, we construct an array with the low-order byte
+		 * (bits 0-7) followed by the second order byte (bit 8).
+		 * BitSet.stream() returns a stream of ints representing those bits that are set.
+		 * We use that stream with a switch to create the set of PosixFilePermissions
+		 * representing the bits that were set in the chmod value.
+		 */
+		BitSet bits = BitSet.valueOf(new byte[] { (byte) chmod, (byte) (chmod >> 8) });
+		final Set<PosixFilePermission> permissions = new HashSet<>();
+		bits.stream().forEach(b -> {
+			switch (b) {
+			case 0:
+				permissions.add(PosixFilePermission.OTHERS_EXECUTE);
+				break;
+			case 1:
+				permissions.add(PosixFilePermission.OTHERS_WRITE);
+				break;
+			case 2:
+				permissions.add(PosixFilePermission.OTHERS_READ);
+				break;
+			case 3:
+				permissions.add(PosixFilePermission.GROUP_EXECUTE);
+				break;
+			case 4:
+				permissions.add(PosixFilePermission.GROUP_WRITE);
+				break;
+			case 5:
+				permissions.add(PosixFilePermission.GROUP_READ);
+				break;
+			case 6:
+				permissions.add(PosixFilePermission.OWNER_EXECUTE);
+				break;
+			case 7:
+				permissions.add(PosixFilePermission.OWNER_WRITE);
+				break;
+			case 8:
+				permissions.add(PosixFilePermission.OWNER_READ);
+				break;
+			}
+		});
+		this.permissions = permissions;
+	}
+
 	@Override
 	protected void doInit() {
 		this.evaluationContext = ExpressionUtils.createStandardEvaluationContext(getBeanFactory());
@@ -414,14 +490,14 @@ public class FileWritingMessageHandler extends AbstractReplyProducingMessageHand
 	private void validateDestinationDirectory(File destinationDirectory, boolean autoCreateDirectory) {
 		if (!destinationDirectory.exists() && autoCreateDirectory) {
 			Assert.isTrue(destinationDirectory.mkdirs(),
-					"Destination directory [" + destinationDirectory + "] could not be created.");
+					() -> "Destination directory [" + destinationDirectory + "] could not be created.");
 		}
 		Assert.isTrue(destinationDirectory.exists(),
-				"Destination directory [" + destinationDirectory + "] does not exist.");
+				() -> "Destination directory [" + destinationDirectory + "] does not exist.");
 		Assert.isTrue(destinationDirectory.isDirectory(),
-				"Destination path [" + destinationDirectory + "] does not point to a directory.");
+				() -> "Destination path [" + destinationDirectory + "] does not point to a directory.");
 		Assert.isTrue(Files.isWritable(destinationDirectory.toPath()),
-				"Destination directory [" + destinationDirectory + "] is not writable.");
+				() -> "Destination directory [" + destinationDirectory + "] is not writable.");
 	}
 
 	@Override
@@ -485,7 +561,7 @@ public class FileWritingMessageHandler extends AbstractReplyProducingMessageHand
 					else {
 						if (this.logger.isWarnEnabled()) {
 							this.logger.warn("Could not set lastModified, header " + FileHeaders.SET_MODIFIED
-									+ " must be a Number, not " + timestamp.getClass());
+									+ " must be a Number, not " + (timestamp == null ? "null" : timestamp.getClass()));
 						}
 					}
 				}
@@ -730,7 +806,7 @@ public class FileWritingMessageHandler extends AbstractReplyProducingMessageHand
 				fileToWriteTo = tempFile;
 				break;
 			default:
-				throw new IllegalStateException("Unsupported FileExistsMode " + this.fileExistsMode);
+				throw new IllegalStateException("Unsupported FileExistsMode: " + this.fileExistsMode);
 		}
 		return fileToWriteTo;
 	}
@@ -745,6 +821,20 @@ public class FileWritingMessageHandler extends AbstractReplyProducingMessageHand
 		if (this.deleteSourceFiles && originalFile != null) {
 			originalFile.delete();
 		}
+
+		setPermissions(resultFile);
+	}
+
+	/**
+	 * Set permissions on newly written files.
+	 * @param resultFile the file.
+	 * @throws IOException any exception.
+	 * @since 5.0
+	 */
+	protected void setPermissions(File resultFile) throws IOException {
+		if (this.permissions != null) {
+			Files.setPosixFilePermissions(resultFile.toPath(), this.permissions);
+		}
 	}
 
 	private void renameTo(File tempFile, File resultFile) throws IOException {

spring-integration-file/src/main/java/org/springframework/integration/file/config/FileWritingMessageHandlerBeanDefinitionBuilder.java

@@ -75,6 +75,7 @@ abstract class FileWritingMessageHandlerBeanDefinitionBuilder {
 		IntegrationNamespaceUtils.setValueIfAttributeDefined(builder, element, "flush-interval");
 		IntegrationNamespaceUtils.setValueIfAttributeDefined(builder, element, "flush-when-idle");
 		IntegrationNamespaceUtils.setReferenceIfAttributeDefined(builder, element, "flush-predicate");
+		IntegrationNamespaceUtils.setValueIfAttributeDefined(builder, element, "chmod");
 		String remoteFileNameGenerator = element.getAttribute("filename-generator");
 		String remoteFileNameGeneratorExpression = element.getAttribute("filename-generator-expression");
 		boolean hasRemoteFileNameGenerator = StringUtils.hasText(remoteFileNameGenerator);

spring-integration-file/src/main/java/org/springframework/integration/file/config/FileWritingMessageHandlerFactoryBean.java

@@ -73,6 +73,8 @@ public class FileWritingMessageHandlerFactoryBean
 
 	private volatile MessageFlushPredicate flushPredicate;
 
+	private String chmod;
+
 	public void setFileExistsMode(String fileExistsModeAsString) {
 		this.fileExistsMode = FileExistsMode.getForString(fileExistsModeAsString);
 	}
@@ -137,6 +139,10 @@ public class FileWritingMessageHandlerFactoryBean
 		this.flushPredicate = flushPredicate;
 	}
 
+	public void setChmod(String chmod) {
+		this.chmod = chmod;
+	}
+
 	@Override
 	protected FileWritingMessageHandler createHandler() {
 
@@ -195,6 +201,9 @@ public class FileWritingMessageHandlerFactoryBean
 		if (this.flushPredicate != null) {
 			handler.setFlushPredicate(this.flushPredicate);
 		}
+		if (this.chmod != null) {
+			handler.setChmodOctal(this.chmod);
+		}
 
 		return handler;
 	}

spring-integration-file/src/main/java/org/springframework/integration/file/dsl/FileWritingMessageHandlerSpec.java

@@ -38,6 +38,7 @@ import org.springframework.util.Assert;
  * The {@link MessageHandlerSpec} for the {@link FileWritingMessageHandler}.
  *
  * @author Artem Bilan
+ * @author Gary Russell
  *
  * @since 5.0
  */
@@ -245,6 +246,20 @@ public class FileWritingMessageHandlerSpec
 		return this;
 	}
 
+	/**
+	 * Set the file permissions after uploading, e.g. 0600 for
+	 * owner read/write. Only applies to file systems that support posix
+	 * file permissions.
+	 * @param chmod the permissions.
+	 * @throws IllegalArgumentException if the value is higher than 0777.
+	 * @return the spec.
+	 * @see FileWritingMessageHandler#setChmod(int)
+	 */
+	public FileWritingMessageHandlerSpec chmod(int chmod) {
+		this.target.setChmod(chmod);
+		return this;
+	}
+
 	@Override
 	public Collection<Object> getComponentsToRegister() {
 		if (this.defaultFileNameGenerator != null) {

spring-integration-file/src/main/java/org/springframework/integration/file/support/FileUtils.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2017 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.
+ * 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 org.springframework.integration.file.support;
+
+import java.nio.file.FileSystems;
+
+/**
+ * Utilities for operations on Files.
+ *
+ * @author Gary Russell
+ * @since 5.0
+ *
+ */
+public final class FileUtils {
+
+	public static final boolean IS_POSIX = FileSystems.getDefault().supportedFileAttributeViews().contains("posix");
+
+	private FileUtils() {
+		super();
+	}
+
+}

spring-integration-file/src/main/resources/org/springframework/integration/file/config/spring-integration-file-5.0.xsd

@@ -597,6 +597,7 @@ Only files matching this regular expression will be picked up by this adapter.
 				</xsd:documentation>
 			</xsd:annotation>
 		</xsd:attribute>
+		<xsd:attributeGroup ref="chmod" />
 		<xsd:attributeGroup ref="integration:smartLifeCycleAttributeGroup"/>
     </xsd:complexType>
 
@@ -1027,4 +1028,15 @@ Only files matching this regular expression will be picked up by this adapter.
 		</xsd:attribute>
 	</xsd:attributeGroup>
 
+	<xsd:attributeGroup name="chmod">
+		<xsd:attribute name="chmod" type="xsd:string">
+			<xsd:annotation>
+				<xsd:documentation>
+					Change the mode of the file (or remote file) after writing. Integer value
+					expressed in Octal, e.g. '644'.
+				</xsd:documentation>
+			</xsd:annotation>
+		</xsd:attribute>
+	</xsd:attributeGroup>
+
 </xsd:schema>