Proof of concept support for native image layers

build-logic/common-plugins/src/main/kotlin/org.graalvm.build.java.gradle.kts

@@ -64,12 +64,16 @@ repositories {
 group = "org.graalvm.buildtools"
 
 extensions.findByType<VersionCatalogsExtension>()?.also { catalogs ->
-    val versionFromCatalog = catalogs.named("libs")
+    if (catalogs.find("libs").isPresent) {
+        val versionFromCatalog = catalogs.named("libs")
             .findVersion("nativeBuildTools")
-    if (versionFromCatalog.isPresent()) {
-        version = versionFromCatalog.get().requiredVersion
+        if (versionFromCatalog.isPresent()) {
+            version = versionFromCatalog.get().requiredVersion
+        } else {
+            throw GradleException("Version catalog doesn't define project version 'nativeBuildTools'")
+        }
     } else {
-        throw GradleException("Version catalog doesn't define project version 'nativeBuildTools'")
+        version = "undefined"
     }
 }
 

common/utils/src/main/java/org/graalvm/buildtools/utils/JarMetadata.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2003-2021 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
+ *
+ *     https://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.graalvm.buildtools.utils;
+
+import java.io.InputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Properties;
+
+public class JarMetadata {
+    private final List<String> packageList;
+
+    public JarMetadata(List<String> packageList) {
+        this.packageList = packageList;
+    }
+
+    public List<String> getPackageList() {
+        return packageList;
+    }
+
+    public static JarMetadata readFrom(Path propertiesFile) {
+        Properties props = new Properties();
+        try (InputStream is = Files.newInputStream(propertiesFile)) {
+            props.load(is);
+        } catch (Exception e) {
+            throw new RuntimeException("Unable to read metadata from properties file " + propertiesFile, e);
+        }
+        String packages = (String) props.get("packages");
+        List<String> packageList = packages == null ? List.of() : Arrays.asList(packages.split(","));
+        return new JarMetadata(packageList);
+    }
+}

common/utils/src/main/java/org/graalvm/buildtools/utils/JarScanner.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2003-2021 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
+ *
+ *     https://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.graalvm.buildtools.utils;
+
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.io.Writer;
+import java.nio.file.FileSystem;
+import java.nio.file.FileSystems;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Set;
+import java.util.TreeSet;
+import java.util.stream.Stream;
+
+/**
+ * Performs scanning of a JAR file and extracts some metadata in the
+ * form of a properties file. For now this type only extracts the list
+ * of packages from a jar.
+ */
+public class JarScanner {
+    /**
+     * Scans a jar and creates a properties file with metadata about the jar contents.
+     * @param inputJar the input jar
+     * @param outputFile the output file
+     * @throws IOException
+     */
+    public static void scanJar(Path inputJar, Path outputFile) throws IOException {
+        try (Writer fileWriter = Files.newBufferedWriter(outputFile); PrintWriter writer = new PrintWriter(fileWriter)) {
+            Set<String> packageList = new TreeSet<>();
+            try (FileSystem jarFileSystem = FileSystems.newFileSystem(inputJar, null)) {
+                Path root = jarFileSystem.getPath("/");
+                try (Stream<Path> files = Files.walk(root)) {
+                    files.forEach(path -> {
+                        if (path.toString().endsWith(".class")) {
+                            Path relativePath = root.relativize(path);
+                            String className = relativePath.toString()
+                                .replace('/', '.')
+                                .replace('\\', '.')
+                                .replace(".class", "");
+                            var lastDot = className.lastIndexOf(".");
+                            if (lastDot > 0) {
+                                packageList.add(className.substring(0, lastDot));
+                            }
+                        }
+                    });
+                }
+            }
+            writer.println("packages=" + String.join(",", packageList));
+        } catch (IOException ex) {
+            throw new RuntimeException("Unable to write JAR analysis", ex);
+        }
+    }
+}