[MNG-6656] Introduce base for build/consumer process

maven-core/pom.xml

@@ -60,6 +60,10 @@ under the License.
       <groupId>org.apache.maven</groupId>
       <artifactId>maven-artifact</artifactId>
     </dependency>
+    <dependency>
+      <groupId>org.apache.maven</groupId>
+      <artifactId>maven-xml</artifactId>
+    </dependency>
     <dependency>
       <groupId>org.apache.maven</groupId>
       <artifactId>maven-plugin-api</artifactId>
@@ -142,6 +146,11 @@ under the License.
       <artifactId>hamcrest-library</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.xmlunit</groupId>
+      <artifactId>xmlunit-assertj</artifactId>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 
   <build>
@@ -218,6 +227,19 @@ under the License.
           </execution>
         </executions>
       </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-failsafe-plugin</artifactId>
+        <executions>
+          <execution>
+            <!--  <phase></phase> -->
+            <goals>
+              <goal>integration-test</goal>
+              <goal>verify</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
     </plugins>
   </build>
 </project>

maven-core/src/main/java/org/apache/maven/internal/aether/ConsumerModelSourceTransformer.java

@@ -0,0 +1,110 @@
+package org.apache.maven.internal.aether;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.
+ */
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import javax.xml.parsers.ParserConfigurationException;
+import javax.xml.stream.XMLInputFactory;
+import javax.xml.stream.XMLStreamException;
+import javax.xml.stream.XMLStreamReader;
+import javax.xml.transform.OutputKeys;
+import javax.xml.transform.Transformer;
+import javax.xml.transform.TransformerConfigurationException;
+import javax.xml.transform.sax.SAXTransformerFactory;
+import javax.xml.transform.sax.TransformerHandler;
+
+import org.apache.maven.model.building.AbstractModelSourceTransformer;
+import org.apache.maven.model.building.DefaultBuildPomXMLFilterFactory;
+import org.apache.maven.model.building.TransformerContext;
+import org.apache.maven.xml.Factories;
+import org.apache.maven.xml.internal.DefaultConsumerPomXMLFilterFactory;
+import org.apache.maven.xml.sax.filter.AbstractSAXFilter;
+import org.xml.sax.SAXException;
+
+class ConsumerModelSourceTransformer extends AbstractModelSourceTransformer
+{
+    @Override
+    protected AbstractSAXFilter getSAXFilter( Path pomFile, TransformerContext context )
+        throws TransformerConfigurationException, SAXException, ParserConfigurationException
+    {
+        return new DefaultConsumerPomXMLFilterFactory( new DefaultBuildPomXMLFilterFactory( context ) ).get( pomFile );
+    }
+
+    /**
+     * This transformer will ensure that encoding and version are kept.
+     * However, it cannot prevent:
+     * <ul>
+     *   <li>attributes will be on one line</li>
+     *   <li>Unnecessary whitespace before the rootelement will be removed</li> 
+     * </ul>
+     */
+    @Override
+    protected TransformerHandler getTransformerHandler( Path pomFile )
+        throws IOException, org.apache.maven.model.building.TransformerException
+    {
+        final TransformerHandler transformerHandler;
+
+        final SAXTransformerFactory transformerFactory =
+                        (SAXTransformerFactory) Factories.newTransformerFactory();
+
+        // Keep same encoding+version
+        try ( InputStream input = Files.newInputStream( pomFile ) )
+        {
+            XMLStreamReader streamReader =
+                XMLInputFactory.newFactory().createXMLStreamReader( input );
+
+            transformerHandler = transformerFactory.newTransformerHandler();
+
+            final String encoding = streamReader.getCharacterEncodingScheme();
+            final String version = streamReader.getVersion();
+
+            Transformer transformer = transformerHandler.getTransformer();
+            transformer.setOutputProperty( OutputKeys.METHOD, "xml" );
+            if ( encoding == null && version == null )
+            {
+                transformer.setOutputProperty( OutputKeys.OMIT_XML_DECLARATION, "yes" );
+            }
+            else
+            {
+                transformer.setOutputProperty( OutputKeys.OMIT_XML_DECLARATION, "no" );
+
+                if ( encoding != null )
+                {
+                    transformer.setOutputProperty( OutputKeys.ENCODING, encoding );
+                }
+                if ( version != null )
+                {
+                    transformer.setOutputProperty( OutputKeys.VERSION, version );
+                }
+            }
+        }
+        catch ( XMLStreamException | TransformerConfigurationException e )
+        {
+            throw new org.apache.maven.model.building.TransformerException( 
+                               "Failed to detect XML encoding and version", e );
+        }
+        return transformerHandler;
+    }
+
+}

maven-core/src/main/java/org/apache/maven/internal/aether/DefaultRepositorySystemSessionFactory.java

@@ -24,6 +24,9 @@
 import org.apache.maven.bridge.MavenRepositorySystem;
 import org.apache.maven.eventspy.internal.EventSpyDispatcher;
 import org.apache.maven.execution.MavenExecutionRequest;
+import org.apache.maven.feature.Features;
+import org.apache.maven.model.building.TransformerContext;
+import org.apache.maven.model.building.TransformerException;
 import org.apache.maven.repository.internal.MavenRepositorySystemUtils;
 import org.apache.maven.settings.Mirror;
 import org.apache.maven.settings.Proxy;
@@ -38,12 +41,16 @@
 import org.eclipse.aether.ConfigurationProperties;
 import org.eclipse.aether.DefaultRepositorySystemSession;
 import org.eclipse.aether.RepositorySystem;
+import org.eclipse.aether.SessionData;
+import org.eclipse.aether.artifact.Artifact;
 import org.eclipse.aether.repository.LocalRepository;
 import org.eclipse.aether.repository.NoLocalRepositoryManagerException;
 import org.eclipse.aether.repository.RepositoryPolicy;
 import org.eclipse.aether.repository.WorkspaceReader;
 import org.eclipse.aether.resolution.ResolutionErrorPolicy;
 import org.eclipse.aether.spi.localrepo.LocalRepositoryManagerFactory;
+import org.eclipse.aether.transform.FileTransformer;
+import org.eclipse.aether.transform.TransformException;
 import org.eclipse.aether.util.repository.AuthenticationBuilder;
 import org.eclipse.aether.util.repository.DefaultAuthenticationSelector;
 import org.eclipse.aether.util.repository.DefaultMirrorSelector;
@@ -53,8 +60,13 @@
 
 import javax.inject.Inject;
 import javax.inject.Named;
+
+import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Properties;
@@ -96,7 +108,6 @@ public class DefaultRepositorySystemSessionFactory
     public DefaultRepositorySystemSession newRepositorySession( MavenExecutionRequest request )
     {
         DefaultRepositorySystemSession session = MavenRepositorySystemUtils.newSession();
-
         session.setCache( request.getRepositoryCache() );
 
         Map<Object, Object> configProps = new LinkedHashMap<>();
@@ -139,7 +150,6 @@ else if ( request.isUpdateSnapshots() )
                 session.setLocalRepositoryManager( simpleLocalRepoMgrFactory.newInstance( session, localRepo ) );
                 logger.info( "Disabling enhanced local repository: using legacy is strongly discouraged to ensure"
                                  + " build reproducibility." );
-
             }
             catch ( NoLocalRepositoryManagerException e )
             {
@@ -238,6 +248,11 @@ else if ( request.isUpdateSnapshots() )
         mavenRepositorySystem.injectProxy( session, request.getPluginArtifactRepositories() );
         mavenRepositorySystem.injectAuthentication( session, request.getPluginArtifactRepositories() );
 
+        if ( Features.buildConsumer().isActive() )
+        {
+            session.setFileTransformerManager( a -> getTransformersForArtifact( a, session.getData() ) );
+        }
+
         return session;
     }
 
@@ -266,5 +281,40 @@ private String getMavenVersion()
 
         return props.getProperty( "version", "unknown-version" );
     }
+
+    private Collection<FileTransformer> getTransformersForArtifact( final Artifact artifact,
+                                                                    final SessionData sessionData )
+    {
+        TransformerContext context = (TransformerContext) sessionData.get( TransformerContext.KEY );
+        Collection<FileTransformer> transformers = new ArrayList<>();
+
+        // In case of install:install-file there's no transformer context, as the goal is unrelated to the lifecycle. 
+        if ( "pom".equals( artifact.getExtension() ) && context != null )
+        {
+            transformers.add( new FileTransformer()
+            {
+                @Override
+                public InputStream transformData( File pomFile )
+                    throws IOException, TransformException
+                {
+                    try
+                    {
+                        return new ConsumerModelSourceTransformer().transform( pomFile.toPath(), context );
+                    }
+                    catch ( TransformerException e )
+                    {
+                        throw new TransformException( e );
+                    }
+                }
+
+                @Override
+                public Artifact transformArtifact( Artifact artifact )
+                {
+                    return artifact;
+                }
+            } );
+        }
+        return Collections.unmodifiableCollection( transformers );
+    }
 
-}
+}