feat: add support for Add-Reads and SplashScreen-Image manifest attributes

docs/modules/ROOT/pages/running.adoc

@@ -183,6 +183,61 @@ If an item has no equals sign and no value than the value is taken to be the str
 //MANIFEST Built-By=Shadowman Sealed
 ----
 
+=== Standard Manifest Attributes
+
+JBang automatically processes certain standard JAR manifest attributes and translates them into appropriate JVM flags when running your code. This allows jars to work correctly even though jbang runs them using classpath mode instead of `-jar` mode.
+
+==== Module System Attributes (Java 9+)
+
+When your jar requires module system flags, jbang will read these from the manifest and apply them automatically:
+
+[source, java]
+----
+//MANIFEST Add-Opens=java.base/java.lang java.base/java.nio
+//MANIFEST Add-Exports=java.base/sun.nio.ch
+//MANIFEST Add-Reads=java.base=java.logging
+----
+
+These translate to JVM flags:
+- `Add-Opens` → `--add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.nio=ALL-UNNAMED`
+- `Add-Exports` → `--add-exports=java.base/sun.nio.ch=ALL-UNNAMED`
+- `Add-Reads` → `--add-reads=java.base=java.logging`
+
+NOTE: Module attributes are only applied when running on Java 9 or later and when not running as a module.
+
+==== Native Access (Java 22+)
+
+For code using the Foreign Function & Memory API:
+
+[source, java]
+----
+//MANIFEST Enable-Native-Access=ALL-UNNAMED
+----
+
+This translates to: `--enable-native-access=ALL-UNNAMED`
+
+==== Splash Screen
+
+For GUI applications with splash screens:
+
+[source, java]
+----
+//MANIFEST SplashScreen-Image=images/splash.png
+----
+
+JBang will extract the image from your jar and pass it via the `-splash` flag. The image is cached to avoid re-extraction on subsequent runs.
+
+==== Using in Plain JARs
+
+These manifest attributes also work when running plain jar files with jbang:
+
+[source, bash]
+----
+$ jbang run myapp.jar
+----
+
+If `myapp.jar` contains `Add-Opens` or other supported attributes in its manifest, jbang will automatically apply them.
+
 
 === (Experimental) Application Class Data Sharing
 

docs/modules/ROOT/pages/script-directives.adoc

@@ -334,7 +334,7 @@ public class ModularApp {
 
 === //MANIFEST
 
-Let you specify the manifest file key-values in the generated jar file xref:running.adoc#adding-entries-to-manifest-mf[].
+Let you specify the manifest file key-values in the generated jar file. See xref:running.adoc#adding-entries-to-manifest-mf[] for full details.
 
 **Syntax**: `//MANIFEST key=value key2=value2 ...`
 
@@ -347,6 +347,17 @@ Let you specify the manifest file key-values in the generated jar file xref:runn
 // Version information
 //MANIFEST Implementation-Version=1.0.0 Implementation-Vendor=MyCompany
 
+// Module system flags (Java 9+)
+//MANIFEST Add-Opens=java.base/java.lang
+//MANIFEST Add-Exports=java.base/sun.nio.ch
+//MANIFEST Add-Reads=java.base=java.logging
+
+// Native access (Java 22+)
+//MANIFEST Enable-Native-Access=ALL-UNNAMED
+
+// Splash screen for GUI apps
+//MANIFEST SplashScreen-Image=images/splash.png
+
 // Boolean flag (no value = true)
 //MANIFEST Custom-Flag Multi-Release
 ----
@@ -355,6 +366,8 @@ Let you specify the manifest file key-values in the generated jar file xref:runn
 
 - Entries without `=value` default to `true`
 - Useful for application metadata
+- Special attributes like `Add-Opens`, `Add-Exports`, `Add-Reads`, `Enable-Native-Access`, and `SplashScreen-Image` are automatically processed by jbang and converted to appropriate JVM flags
+- Values can contain `=` signs (e.g., `Add-Reads=mod1=mod2`)
 
 == Performance Optimization
 

src/main/java/dev/jbang/source/Project.java

@@ -54,6 +54,11 @@ public class Project {
 
 	public static final String ATTR_PREMAIN_CLASS = "Premain-Class";
 	public static final String ATTR_AGENT_CLASS = "Agent-Class";
+	public static final String ATTR_ADD_EXPORTS = "Add-Exports";
+	public static final String ATTR_ADD_OPENS = "Add-Opens";
+	public static final String ATTR_ENABLE_NATIVE_ACCESS = "Enable-Native-Access";
+	public static final String ATTR_ADD_READS = "Add-Reads";
+	public static final String ATTR_SPLASH_SCREEN_IMAGE = "SplashScreen-Image";
 
 	public enum BuildFile {
 		jbang("build.jbang");

src/main/java/dev/jbang/source/ProjectBuilder.java

@@ -444,13 +444,25 @@ private Project importJarMetadata(Project prj, boolean importModuleName) {
 					// TODO: this does mean we can't separate from user specified options and jar
 					// origined ones, but not sure if needed?
 					// https://openjdk.org/jeps/261#Breaking-encapsulation
-					String exports = attrs.getValue("Add-Exports");
+					String exports = attrs.getValue(Project.ATTR_ADD_EXPORTS);
 					if (exports != null) {
-						prj.getManifestAttributes().put("Add-Exports", exports);
+						prj.getManifestAttributes().put(Project.ATTR_ADD_EXPORTS, exports);
 					}
-					String opens = attrs.getValue("Add-Opens");
+					String opens = attrs.getValue(Project.ATTR_ADD_OPENS);
 					if (opens != null) {
-						prj.getManifestAttributes().put("Add-Opens", exports);
+						prj.getManifestAttributes().put(Project.ATTR_ADD_OPENS, opens);
+					}
+					String enableNativeAccess = attrs.getValue(Project.ATTR_ENABLE_NATIVE_ACCESS);
+					if (enableNativeAccess != null) {
+						prj.getManifestAttributes().put(Project.ATTR_ENABLE_NATIVE_ACCESS, enableNativeAccess);
+					}
+					String addReads = attrs.getValue(Project.ATTR_ADD_READS);
+					if (addReads != null) {
+						prj.getManifestAttributes().put(Project.ATTR_ADD_READS, addReads);
+					}
+					String splashScreenImage = attrs.getValue(Project.ATTR_SPLASH_SCREEN_IMAGE);
+					if (splashScreenImage != null) {
+						prj.getManifestAttributes().put(Project.ATTR_SPLASH_SCREEN_IMAGE, splashScreenImage);
 					}
 
 				}

src/main/java/dev/jbang/source/generators/JarCmdGenerator.java

@@ -5,6 +5,7 @@
 import java.net.ServerSocket;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -13,6 +14,8 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
+import java.util.jar.JarEntry;
+import java.util.jar.JarFile;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
@@ -85,6 +88,10 @@ public JarCmdGenerator(BuildContext ctx) {
 		super(ctx);
 	}
 
+	private boolean isRunAsModule() {
+		return moduleName != null && ctx.getProject().getModuleName().isPresent();
+	}
+
 	@Override
 	protected List<String> generateCommandLineList() throws IOException {
 		List<String> fullArgs = new ArrayList<>();
@@ -97,18 +104,58 @@ protected List<String> generateCommandLineList() throws IOException {
 		Jdk jdk = project.projectJdk();
 		String javacmd = JavaUtil.resolveInJavaHome("java", jdk);
 
-		if (jdk.majorVersion() > 9) {
-			String opens = ctx.getProject().getManifestAttributes().get("Add-Opens");
+		// Handle splash screen - extract image from jar and pass -splash:path
+		String splashImage = project.getManifestAttributes().get(Project.ATTR_SPLASH_SCREEN_IMAGE);
+		if (splashImage != null) {
+			Path jarPath = ctx.getJarFile();
+			if (jarPath != null && Files.exists(jarPath)) {
+				Path splashPath = extractSplashImage(jarPath, splashImage);
+				if (splashPath != null) {
+					optionalArgs.add("-splash:" + splashPath.toAbsolutePath());
+				}
+			}
+		}
+
+		if (!isRunAsModule() && jdk.majorVersion() >= 9) {
+			String opens = project.getManifestAttributes().get(Project.ATTR_ADD_OPENS);
 			if (opens != null) {
-				for (String val : opens.split(" ")) {
-					optionalArgs.add("--add-opens=" + val + "=ALL-UNNAMED");
+				for (String val : opens.trim().split("\\s+")) {
+					if (!val.isEmpty()) {
+						optionalArgs.add("--add-opens=" + val + "=ALL-UNNAMED");
+					}
 				}
 			}
 
-			String exports = ctx.getProject().getManifestAttributes().get("Add-Exports");
+			String exports = project.getManifestAttributes().get(Project.ATTR_ADD_EXPORTS);
 			if (exports != null) {
-				for (String val : exports.split(" ")) {
-					optionalArgs.add("--add-exports=" + val + "=ALL-UNNAMED");
+				for (String val : exports.trim().split("\\s+")) {
+					if (!val.isEmpty()) {
+						optionalArgs.add("--add-exports=" + val + "=ALL-UNNAMED");
+					}
+				}
+			}
+
+			// Add-Reads: module1=module2 module3=module4 → --add-reads=module1=module2
+			// --add-reads=module3=module4
+			String addReads = project.getManifestAttributes().get(Project.ATTR_ADD_READS);
+			if (addReads != null) {
+				for (String val : addReads.trim().split("\\s+")) {
+					if (!val.isEmpty()) {
+						optionalArgs.add("--add-reads=" + val);
+					}
+				}
+			}
+		}
+
+		if (!isRunAsModule() && jdk.majorVersion() >= 22) {
+			String nativeAccess = project.getManifestAttributes().get(Project.ATTR_ENABLE_NATIVE_ACCESS);
+			if (nativeAccess != null) {
+				nativeAccess = nativeAccess.trim();
+				if ("ALL-UNNAMED".equals(nativeAccess)) {
+					optionalArgs.add("--enable-native-access=" + nativeAccess);
+				} else {
+					throw new ExitException(BaseCommand.EXIT_INVALID_INPUT,
+							"Invalid value for manifest attribute Enable-Native-Access: " + nativeAccess);
 				}
 			}
 		}
@@ -197,7 +244,7 @@ protected List<String> generateCommandLineList() throws IOException {
 			}
 		}
 		if (!Util.isBlankString(classpath)) {
-			if (moduleName != null && project.getModuleName().isPresent()) {
+			if (isRunAsModule()) {
 				optionalArgs.addAll(Arrays.asList("-p", classpath));
 			} else {
 				optionalArgs.addAll(Arrays.asList("-classpath", classpath));
@@ -230,7 +277,7 @@ protected List<String> generateCommandLineList() throws IOException {
 
 		String main = Optional.ofNullable(mainClass).orElse(project.getMainClass());
 		if (main != null && !Glob.isGlob(main)) {
-			if (moduleName != null && project.getModuleName().isPresent()) {
+			if (isRunAsModule()) {
 				String modName = moduleName.isEmpty() ? ModuleUtil.getModuleName(project) : moduleName;
 				fullArgs.add("-m");
 				fullArgs.add(modName + "/" + main);
@@ -316,4 +363,62 @@ private static void addPropertyFlags(Map<String, String> properties, String def,
 		properties.forEach((k, e) -> result.add(def + k + "=" + e));
 	}
 
+	/**
+	 * Extract splash screen image from jar to cache directory for use with -splash
+	 * flag.
+	 *
+	 * @param jarPath   Path to the jar file
+	 * @param imagePath Path to image inside jar (from manifest SplashScreen-Image
+	 *                  attribute)
+	 * @return Path to extracted image, or null if extraction failed
+	 */
+	private static Path extractSplashImage(Path jarPath, String imagePath) {
+		// Validate image path for security
+		if (imagePath == null || imagePath.trim().isEmpty()) {
+			Util.warnMsg("Splash screen image path is empty");
+			return null;
+		}
+
+		// Normalize and validate path to prevent directory traversal attacks
+		String normalizedPath = imagePath.replace('\\', '/');
+		if (normalizedPath.startsWith("/") || normalizedPath.contains("../") || normalizedPath.contains("..\\")) {
+			Util.warnMsg("Invalid splash screen image path (absolute or contains '..'): " + imagePath);
+			return null;
+		}
+
+		try (JarFile jar = new JarFile(jarPath.toFile())) {
+			JarEntry entry = jar.getJarEntry(normalizedPath);
+			if (entry == null) {
+				Util.warnMsg("Splash screen image not found in jar: " + imagePath);
+				return null;
+			}
+
+			// Reject directory entries
+			if (entry.isDirectory()) {
+				Util.warnMsg("Splash screen image path is a directory: " + imagePath);
+				return null;
+			}
+
+			// Extract to jar's directory with unique name
+			String jarName = jarPath.getFileName().toString();
+			int extIndex = normalizedPath.lastIndexOf('.');
+			String imageExt = (extIndex > 0) ? normalizedPath.substring(extIndex) : "";
+			Path targetPath = jarPath.getParent().resolve(jarName + ".splash" + imageExt);
+
+			// Extract if not cached or jar is newer
+			if (!Files.exists(targetPath) ||
+					Files.getLastModifiedTime(jarPath).compareTo(Files.getLastModifiedTime(targetPath)) > 0) {
+				try (InputStream is = jar.getInputStream(entry)) {
+					Files.copy(is, targetPath, StandardCopyOption.REPLACE_EXISTING);
+				}
+				Util.verboseMsg("Extracted splash screen to: " + targetPath);
+			}
+
+			return targetPath;
+		} catch (IOException e) {
+			Util.warnMsg("Failed to extract splash screen: " + e.getMessage());
+			return null;
+		}
+	}
+
 }

src/main/java/dev/jbang/source/parser/KeyValue.java

@@ -18,7 +18,7 @@ public String getValue() {
 	}
 
 	public static KeyValue of(String line) {
-		String[] split = line.split("=");
+		String[] split = line.split("=", 2);
 		String key;
 		String value = null;