Normalize filename for single file downloads

Closes gh-50087

spring-boot-project/spring-boot-tools/spring-boot-cli/src/main/java/org/springframework/boot/cli/command/init/InitializrService.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.cli.command.init;
 
+import java.io.File;
 import java.io.IOException;
 import java.net.URI;
 import java.nio.charset.Charset;
@@ -242,7 +243,7 @@ class InitializrService {
 				value = value.substring(start + FILENAME_HEADER_PREFIX.length());
 				int end = value.indexOf('\"');
 				if (end != -1) {
-					return value.substring(0, end);
+					return new File(value.substring(0, end)).getName();
 				}
 			}
 		}

spring-boot-project/spring-boot-tools/spring-boot-cli/src/main/java/org/springframework/boot/cli/command/init/ProjectGenerator.java

@@ -131,7 +131,7 @@ class ProjectGenerator {
 	}
 
 	private void writeProject(ProjectGenerationResponse entity, String output, boolean overwrite) throws IOException {
-		File outputFile = new File(output);
+		File outputFile = new File(System.getProperty("user.dir"), output);
 		if (outputFile.exists()) {
 			if (!overwrite) {
 				throw new ReportableException(

spring-boot-project/spring-boot-tools/spring-boot-cli/src/test/java/org/springframework/boot/cli/command/init/InitCommandTests.java

@@ -26,6 +26,7 @@ import java.util.zip.ZipOutputStream;
 
 import joptsimple.OptionSet;
 import org.apache.hc.core5.http.HttpHost;
+import org.assertj.core.api.SoftAssertionsProvider.ThrowingRunnable;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.junit.jupiter.api.io.TempDir;
@@ -213,26 +214,30 @@ class InitCommandTests extends AbstractHttpClientMockTests {
 
 	@Test
 	void fileNotOverwrittenByDefault(@TempDir File tempDir) throws Exception {
-		File file = new File(tempDir, "test.file");
-		file.createNewFile();
-		long fileLength = file.length();
-		MockHttpProjectGenerationRequest request = new MockHttpProjectGenerationRequest("application/zip",
-				file.getAbsolutePath());
-		mockSuccessfulProjectGeneration(request);
-		assertThat(this.command.run()).as("Should have failed").isEqualTo(ExitStatus.ERROR);
-		assertThat(file.length()).as("File should not have changed").isEqualTo(fileLength);
+		withUserDir(tempDir, () -> {
+			File file = new File(tempDir, "test.file");
+			file.createNewFile();
+			long fileLength = file.length();
+			MockHttpProjectGenerationRequest request = new MockHttpProjectGenerationRequest("application/zip",
+					file.getAbsolutePath());
+			mockSuccessfulProjectGeneration(request);
+			assertThat(this.command.run()).as("Should have failed").isEqualTo(ExitStatus.ERROR);
+			assertThat(file.length()).as("File should not have changed").isEqualTo(fileLength);
+		});
 	}
 
 	@Test
 	void overwriteFile(@TempDir File tempDir) throws Exception {
-		File file = new File(tempDir, "test.file");
-		file.createNewFile();
-		long fileLength = file.length();
-		MockHttpProjectGenerationRequest request = new MockHttpProjectGenerationRequest("application/zip",
-				file.getAbsolutePath());
-		mockSuccessfulProjectGeneration(request);
-		assertThat(this.command.run("--force")).isEqualTo(ExitStatus.OK);
-		assertThat(fileLength).as("File should have changed").isNotEqualTo(file.length());
+		withUserDir(tempDir, () -> {
+			File file = new File(tempDir, "test.file");
+			file.createNewFile();
+			long fileLength = file.length();
+			MockHttpProjectGenerationRequest request = new MockHttpProjectGenerationRequest("application/zip",
+					file.getAbsolutePath());
+			mockSuccessfulProjectGeneration(request);
+			assertThat(this.command.run("--force")).isEqualTo(ExitStatus.OK);
+			assertThat(fileLength).as("File should have changed").isNotEqualTo(file.length());
+		});
 	}
 
 	@Test
@@ -399,6 +404,17 @@ class InitCommandTests extends AbstractHttpClientMockTests {
 					request.getHeaders("User-Agent")[0].getValue().startsWith("SpringBootCli/"))), isNull());
 	}
 
+	private void withUserDir(File userDir, ThrowingRunnable action) throws Exception {
+		String previous = System.getProperty("user.dir");
+		System.setProperty("user.dir", userDir.getAbsolutePath());
+		try {
+			action.run();
+		}
+		finally {
+			System.setProperty("user.dir", previous);
+		}
+	}
+
 	private byte[] createFakeZipArchive(String fileName, String content) throws IOException {
 		try (ByteArrayOutputStream bos = new ByteArrayOutputStream()) {
 			try (ZipOutputStream zos = new ZipOutputStream(bos)) {

spring-boot-project/spring-boot-tools/spring-boot-cli/src/test/java/org/springframework/boot/cli/command/init/InitializrServiceTests.java

@@ -49,9 +49,9 @@ class InitializrServiceTests extends AbstractHttpClientMockTests {
 	void generateSimpleProject() throws Exception {
 		ProjectGenerationRequest request = new ProjectGenerationRequest();
 		MockHttpProjectGenerationRequest mockHttpRequest = new MockHttpProjectGenerationRequest("application/xml",
-				"foo.zip");
+				"nested/path/foo.zip");
 		ProjectGenerationResponse entity = generateProject(request, mockHttpRequest);
-		assertProjectEntity(entity, mockHttpRequest.contentType, mockHttpRequest.fileName);
+		assertProjectEntity(entity, mockHttpRequest.contentType, "foo.zip");
 	}
 
 	@Test