Merge branch '2.1.x'

Closes gh-18168

spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/CentralDirectoryEndRecord.java

@@ -123,4 +123,10 @@ class CentralDirectoryEndRecord {
 		return (int) numberOfRecords;
 	}
 
+	String getComment() {
+		int commentLength = (int) Bytes.littleEndianValue(this.block, this.offset + COMMENT_LENGTH_OFFSET, 2);
+		AsciiBytes comment = new AsciiBytes(this.block, this.offset + COMMENT_LENGTH_OFFSET + 2, commentLength);
+		return comment.toString();
+	}
+
 }

spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarFile.java

@@ -80,6 +80,8 @@ public class JarFile extends java.util.jar.JarFile {
 
 	private boolean signed;
 
+	private String comment;
+
 	/**
 	 * Create a new {@link JarFile} backed by the specified file.
 	 * @param file the root jar file
@@ -146,6 +148,7 @@ public class JarFile extends java.util.jar.JarFile {
 
 			@Override
 			public void visitStart(CentralDirectoryEndRecord endRecord, RandomAccessData centralDirectoryData) {
+				JarFile.this.comment = endRecord.getComment();
 			}
 
 			@Override
@@ -290,6 +293,11 @@ public class JarFile extends java.util.jar.JarFile {
 				JarFileType.NESTED_JAR);
 	}
 
+	@Override
+	public String getComment() {
+		return this.comment;
+	}
+
 	@Override
 	public int size() {
 		return this.entries.getSize();

spring-boot-project/spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/TestJarCreator.java

@@ -41,6 +41,7 @@ public abstract class TestJarCreator {
 	public static void createTestJar(File file, boolean unpackNested) throws Exception {
 		FileOutputStream fileOutputStream = new FileOutputStream(file);
 		try (JarOutputStream jarOutputStream = new JarOutputStream(fileOutputStream)) {
+			jarOutputStream.setComment("outer");
 			writeManifest(jarOutputStream, "j1");
 			writeEntry(jarOutputStream, "1.dat", 1);
 			writeEntry(jarOutputStream, "2.dat", 2);
@@ -88,6 +89,7 @@ public abstract class TestJarCreator {
 	private static byte[] getNestedJarData(boolean multiRelease) throws Exception {
 		ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
 		JarOutputStream jarOutputStream = new JarOutputStream(byteArrayOutputStream);
+		jarOutputStream.setComment("nested");
 		writeManifest(jarOutputStream, "j2", multiRelease);
 		if (multiRelease) {
 			writeEntry(jarOutputStream, "multi-release.dat", 8);

spring-boot-project/spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/jar/JarFileTests.java

@@ -86,6 +86,7 @@ class JarFileTests {
 	void jdkJarFile() throws Exception {
 		// Sanity checks to see how the default jar file operates
 		java.util.jar.JarFile jarFile = new java.util.jar.JarFile(this.rootJarFile);
+		assertThat(jarFile.getComment()).isEqualTo("outer");
 		Enumeration<java.util.jar.JarEntry> entries = jarFile.entries();
 		assertThat(entries.nextElement().getName()).isEqualTo("META-INF/");
 		assertThat(entries.nextElement().getName()).isEqualTo("META-INF/MANIFEST.MF");
@@ -168,6 +169,11 @@ class JarFileTests {
 		assertThat(inputStream.read()).isEqualTo(-1);
 	}
 
+	@Test
+	void getComment() {
+		assertThat(this.jarFile.getComment()).isEqualTo("outer");
+	}
+
 	@Test
 	void getName() {
 		assertThat(this.jarFile.getName()).isEqualTo(this.rootJarFile.getPath());
@@ -252,6 +258,7 @@ class JarFileTests {
 	@Test
 	void getNestedJarFile() throws Exception {
 		try (JarFile nestedJarFile = this.jarFile.getNestedJarFile(this.jarFile.getEntry("nested.jar"))) {
+			assertThat(nestedJarFile.getComment()).isEqualTo("nested");
 			Enumeration<java.util.jar.JarEntry> entries = nestedJarFile.entries();
 			assertThat(entries.nextElement().getName()).isEqualTo("META-INF/");
 			assertThat(entries.nextElement().getName()).isEqualTo("META-INF/MANIFEST.MF");