Follow P2 contract of cached file's extension (eclipse-tycho#2938)

P2 relies on correct file extensions to parse cached files.

Fixes eclipse-tycho#2938

See
eclipse-equinox/p2#355

p2-maven-plugin/src/main/java/org/eclipse/tycho/p2maven/transport/SharedHttpCacheStorage.java

@@ -262,8 +262,16 @@ public synchronized File fetchFile(URI uri, HttpTransportFactory transportFactor
 				}
 				updateHeader(response, code);
 				if (isRedirected(code)) {
-					return SharedHttpCacheStorage.this.getCacheEntry(getRedirect(uri), logger)
+					File cachedFile = SharedHttpCacheStorage.this.getCacheEntry(getRedirect(uri), logger)
 							.getCacheFile(transportFactory);
+					// https://github.com/eclipse-tycho/tycho/issues/2938
+					// Redirect may change extension. P2's SimpleMetadataRepositoryFactory relies on
+					// accurate file extension to be cached.
+					// Copying file to accommodate original request and its file extension.
+					// Once https://github.com/eclipse-equinox/p2/issues/355 is fixed, cachedFile
+					// may be returned directly without copying.
+					FileUtils.copyFile(cachedFile, file);
+					return file;
 				}
 				if (exits) {
 					FileUtils.forceDelete(file);

tycho-its/projects/target.content_jar/category.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<site>
+   <feature id="issue_2938_reproducer"/>
+</site>

tycho-its/projects/target.content_jar/pom.xml

@@ -0,0 +1,49 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>tycho-its-project.p2Repository.slicerDependencies</groupId>
+    <artifactId>aggregator</artifactId>
+    <version>1.0.0</version>
+    <packaging>eclipse-repository</packaging>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.eclipse.tycho</groupId>
+                <artifactId>tycho-maven-plugin</artifactId>
+                <version>${tycho-version}</version>
+                <extensions>true</extensions>
+            </plugin>
+            <plugin>
+                <groupId>org.eclipse.tycho</groupId>
+                <artifactId>target-platform-configuration</artifactId>
+                <version>${tycho-version}</version>
+                <configuration>
+                    <resolver>p2</resolver>
+                    <executionEnvironment>JavaSE-11</executionEnvironment>
+                    <target>
+						<file>targetplatform.target</file>
+                    </target>
+                    <environments>
+                        <environment>
+                            <os>win32</os>
+                            <ws>win32</ws>
+                            <arch>x86_64</arch>
+                        </environment>
+                        <environment>
+                            <os>linux</os>
+                            <ws>gtk</ws>
+                            <arch>x86_64</arch>
+                        </environment>
+                    </environments>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

tycho-its/projects/target.content_jar/targetplatform.target

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<?pde?>
+<target name="p2Repository.slicerDependencies" sequenceNumber="1">
+    <locations>
+        <location includeAllPlatforms="false" includeConfigurePhase="true" includeMode="slicer" includeSource="true" type="InstallableUnit">
+            <repository id="repoA" location="url"/>
+
+            <unit id="issue_2938_reproducer.feature.group" version="0.0.0"/>
+        </location>
+    </locations>
+</target>

tycho-its/src/test/java/org/eclipse/tycho/test/tycho2938/ContentJarTest.java

@@ -0,0 +1,120 @@
+/*******************************************************************************
+ * Copyright (c) 2023, 2023 Sonatype Inc. and others.
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *    Vasili Gulevich - initial implementation
+ *******************************************************************************/
+package org.eclipse.tycho.test.tycho2938;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.FileVisitResult;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.SimpleFileVisitor;
+import java.nio.file.attribute.BasicFileAttributes;
+import java.util.Arrays;
+
+import org.apache.commons.io.FileUtils;
+import org.apache.maven.it.VerificationException;
+import org.apache.maven.it.Verifier;
+import org.eclipse.tycho.test.AbstractTychoIntegrationTest;
+import org.eclipse.tycho.test.util.HttpServer;
+import org.eclipse.tycho.test.util.ResourceUtil;
+import org.eclipse.tycho.test.util.TargetDefinitionUtil;
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+public class ContentJarTest extends AbstractTychoIntegrationTest {
+	private HttpServer server;
+	@Rule
+	public final TemporaryFolder temporaryFolder = new TemporaryFolder();
+
+	@Before
+	public void startServer() throws Exception {
+		server = HttpServer.startServer();
+		File originalResource = ResourceUtil.resolveTestResource("repositories/content_jar");
+		FileUtils.copyDirectory(originalResource, temporaryFolder.getRoot());
+	}
+
+	@After
+	public void stopServer() throws Exception {
+		if (server != null) {
+			server.stop();
+		}
+	}
+
+	private void mangleFileNames(Path repositoryRoot) throws IOException {
+		Files.walkFileTree(repositoryRoot, new SimpleFileVisitor<Path>() {
+			@Override
+			public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
+				Files.move(file, file.getParent().resolve(file.getFileName() + "_invalid"));
+				return super.visitFile(file, attrs);
+			}
+		});
+	}
+
+	@Test
+	public void noRedirect() throws Exception {
+		File repositoryRoot = temporaryFolder.getRoot();
+		String repoUrl = server.addServer("repoA", repositoryRoot);
+		Verifier verifier = getVerifier("target.content_jar", false);
+		File platformFile = new File(verifier.getBasedir(), "targetplatform.target");
+		TargetDefinitionUtil.setRepositoryURLs(platformFile, "repoA", repoUrl);
+		verifier.executeGoals(Arrays.asList("package"));
+		verifier.verifyErrorFreeLog();
+	}
+
+	@Test
+	public void redirectKeepFilename() throws Exception {
+		File repositoryRoot = temporaryFolder.getRoot();
+		String repoUrl = server.addServer("repoA", repositoryRoot);
+		String redirectedUrl = server.addRedirect("repoB", originalPath -> repoUrl + originalPath);
+		Verifier verifier = getVerifier("target.content_jar", false);
+		File platformFile = new File(verifier.getBasedir(), "targetplatform.target");
+		TargetDefinitionUtil.setRepositoryURLs(platformFile, "repoA", redirectedUrl);
+		verifier.executeGoals(Arrays.asList("package"));
+		verifier.verifyErrorFreeLog();
+	}
+
+	@Test
+	public void redirectToBadLocation() throws Exception {
+		File repositoryRoot = temporaryFolder.getRoot();
+		String repoUrl = server.addServer("repoA", repositoryRoot);
+		String redirectedUrl = server.addRedirect("repoB", originalPath -> repoUrl + originalPath + "_invalid");
+		Verifier verifier = getVerifier("target.content_jar", false);
+		File platformFile = new File(verifier.getBasedir(), "targetplatform.target");
+		TargetDefinitionUtil.setRepositoryURLs(platformFile, "repoA", redirectedUrl);
+		Assert.assertThrows(VerificationException.class, () -> verifier.executeGoal("package"));
+
+		verifier.verifyTextInLog("No repository found at " + redirectedUrl);
+	}
+
+	@Test
+	public void redirectToMangledLocations() throws Exception {
+		File repositoryRoot = temporaryFolder.getRoot();
+		mangleFileNames(repositoryRoot.toPath());
+		String mangledRepoUrl = server.addServer("repoA", repositoryRoot);
+
+		// https://github.com/eclipse-tycho/tycho/issues/2938
+		// Redirect may change extension.
+		String originaRepoUrl = server.addRedirect("repoB", originalPath -> mangledRepoUrl + originalPath + "_invalid");
+
+		Verifier verifier = getVerifier("target.content_jar", false);
+		File platformFile = new File(verifier.getBasedir(), "targetplatform.target");
+		TargetDefinitionUtil.setRepositoryURLs(platformFile, "repoA", originaRepoUrl);
+		verifier.executeGoals(Arrays.asList("package"));
+		verifier.verifyErrorFreeLog();
+	}
+
+}

tycho-its/src/test/java/org/eclipse/tycho/test/util/HttpServer.java

@@ -19,8 +19,10 @@
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.TimeUnit;
+import java.util.function.Function;
 
 import javax.servlet.ServletException;
+import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
@@ -74,6 +76,21 @@ protected void doPost(HttpServletRequest request, HttpServletResponse response)
 		}
 	}
 
+	private static class RedirectServlet extends HttpServlet {
+		private final Function<String, String> relativeUrlToNewUrl;
+
+		public RedirectServlet(Function<String, String> relativeUrlToNewUrl2) {
+			super();
+			this.relativeUrlToNewUrl = relativeUrlToNewUrl2;
+		}
+
+		@Override
+		protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
+			resp.sendRedirect(relativeUrlToNewUrl.apply(req.getServletPath()));
+		}
+
+	}
+
 	private static final int BIND_ATTEMPTS = 20;
 
 	private final Server server;
@@ -155,16 +172,32 @@ public String addServer(String contextName, final File content) {
 		ServletContextHandler context = new ServletContextHandler(contexts, URIUtil.SLASH + contextName);
 		context.setResourceBase(content.getAbsolutePath());
 
+		addMonitoring(contextName, context);
+		try {
+			context.start();
+		} catch (Exception e) {
+			throw new RuntimeException(e);
+		}
+		return getUrl(contextName);
+	}
+
+	private void addMonitoring(String contextName, ServletContextHandler context) {
 		MonitoringServlet monitoringServlet = new MonitoringServlet();
 		contextName2servletsMap.put(contextName, monitoringServlet);
 		context.addServlet(new ServletHolder(monitoringServlet), URIUtil.SLASH);
 		contexts.addHandler(context);
+	}
+
+	public String addRedirect(String contextName, Function<String, String> relativeUrlToNewUrl) {
+		ServletContextHandler context = new ServletContextHandler(contexts, URIUtil.SLASH + contextName);
+		context.addServlet(new ServletHolder(new RedirectServlet(relativeUrlToNewUrl)), URIUtil.SLASH);
 		try {
 			context.start();
 		} catch (Exception e) {
 			throw new RuntimeException(e);
 		}
 		return getUrl(contextName);
+
 	}
 
 	public String getUrl(String contextName) {