fix: avoid replacing active Windows command launcher (jbangdev#2617)

Signed-off-by: Arnab Nandy <arnab_nandy7@yahoo.com>

Author: arnabnandy7

docs/modules/ROOT/pages/installation.adoc

@@ -74,6 +74,17 @@ For example `iex "& { $(iwr -useb https://ps.jbang.dev) } properties@jbangdev"`
 
 Unzip the https://github.com/jbangdev/jbang/releases/latest[latest binary release], add the `jbang-<version>/bin` folder to your `$PATH` and you are set.
 
+=== Updating a JBang-managed installation
+
+If JBang was installed using the universal installation script, update it with:
+
+[source,shell]
+----
+jbang version --update
+----
+
+When JBang was installed using a package manager such as SDKMAN, Homebrew, Chocolatey, or Scoop, use that package manager's upgrade command instead.
+
 === Wrapper install
 
 If you would like to have `jbang` available in a local directory and committed into a source code repository (akin to Maven and Gradle wrappers) you can use the `jbang wrapper` command.
@@ -623,4 +634,4 @@ The following variables are set *by* the scripts for use by JBang's Java code an
 | `JBANG_LAUNCH_CMD`
 | Path to the script that was invoked.
 
-|===
+|===

src/main/java/dev/jbang/cli/App.java

@@ -253,14 +253,18 @@ public static boolean installJBang(boolean force) throws IOException {
 			return true;
 		}
 
-		private static void copyJBangFiles(Path from, Path to) throws IOException {
+		static void copyJBangFiles(Path from, Path to) throws IOException {
 			to.toFile().mkdirs();
 			Stream.of("jbang", "jbang.cmd", "jbang.ps1", "jbang.jar")
 				.map(Paths::get)
 				.forEach(f -> {
 					try {
 						Path fromp = from.resolve(f);
 						Path top = to.resolve(f);
+						if (Util.isWindows() && f.endsWith("jbang.cmd") && Files.isRegularFile(top)) {
+							top = top.resolveSibling(top.getFileName() + ".new");
+							Util.verboseMsg("Staging the Windows command launcher update: " + top);
+						}
 						if (f.endsWith("jbang.jar")) {
 							if (!Files.isReadable(fromp)) {
 								fromp = from.resolve(".jbang/jbang.jar");
@@ -275,6 +279,32 @@ private static void copyJBangFiles(Path from, Path to) throws IOException {
 						throw new ExitException(EXIT_GENERIC_ERROR, "Could not copy " + f.toString(), e);
 					}
 				});
+			if (Util.isWindows() && Util.getShell() != Util.Shell.cmd) {
+				replaceStagedCmdLauncher(to);
+			}
+		}
+
+		static String cmdLauncherUpdateCommand() {
+			if (!Util.isWindows() || Util.getShell() != Util.Shell.cmd) {
+				return null;
+			}
+			Path launcher = Settings.getConfigBinDir().resolve("jbang.cmd");
+			Path launcherUpdate = launcher.resolveSibling(launcher.getFileName() + ".new");
+			if (!Files.isRegularFile(launcherUpdate)) {
+				return null;
+			}
+			String moveCommand = CommandBuffer.of("move", "/y", launcherUpdate.toString(), launcher.toString())
+				.shell(Util.Shell.cmd)
+				.asCommandLine();
+			return moveCommand + " > nul 2>&1 && exit /b 0 || exit /b 1";
+		}
+
+		private static void replaceStagedCmdLauncher(Path binDir) throws IOException {
+			Path launcher = binDir.resolve("jbang.cmd");
+			Path launcherUpdate = launcher.resolveSibling(launcher.getFileName() + ".new");
+			if (Files.isRegularFile(launcherUpdate)) {
+				Files.move(launcherUpdate, launcher, StandardCopyOption.REPLACE_EXISTING);
+			}
 		}
 	}
 

src/main/java/dev/jbang/cli/Version.java

@@ -50,6 +50,14 @@ public Integer doCall() {
 			System.err.println("Native Image: " + JavaUtil.inNativeImage());
 		}
 
+		if (update) {
+			String cmdLauncherUpdate = App.AppInstall.cmdLauncherUpdateCommand();
+			if (cmdLauncherUpdate != null) {
+				System.out.println(cmdLauncherUpdate);
+				return EXIT_EXECUTE;
+			}
+		}
+
 		return EXIT_OK;
 	}
 }

src/main/java/dev/jbang/util/Util.java

@@ -84,6 +84,7 @@ public class Util {
 
 	public static final String JBANG_JDK_VENDOR = "JBANG_JDK_VENDOR";
 	public static final String JBANG_RUNTIME_SHELL = "JBANG_RUNTIME_SHELL";
+	public static final String JBANG_LAUNCH_CMD = "JBANG_LAUNCH_CMD";
 	public static final String JBANG_STDIN_NOTTY = "JBANG_STDIN_NOTTY";
 	public static final String JBANG_PREFER_GUI = "JBANG_PREFER_GUI";
 	private static final String JBANG_DOWNLOAD_SOURCES = "JBANG_DOWNLOAD_SOURCES";

src/test/java/dev/jbang/cli/TestApp.java

@@ -16,6 +16,8 @@
 import org.junit.Assert;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.Timeout;
+import org.junit.jupiter.api.condition.EnabledOnOs;
+import org.junit.jupiter.api.condition.OS;
 import org.junit.jupiter.api.io.TempDir;
 
 import dev.jbang.BaseTest;
@@ -60,6 +62,55 @@ void testHasJBangSetup(@TempDir Path tempDir) throws IOException {
 		assertThat(App.AppSetup.hasJBangSetup(rcFile), is(true));
 	}
 
+	@Test
+	@EnabledOnOs(OS.WINDOWS)
+	void testUpdateStagesWindowsCmdLauncher(@TempDir Path tempDir) throws IOException, InterruptedException {
+		Path source = Files.createDirectory(tempDir.resolve("source"));
+		Path target = Settings.getConfigBinDir();
+		Files.createDirectories(target);
+		Files.writeString(source.resolve("jbang"), "new sh");
+		Files.writeString(source.resolve("jbang.cmd"), "new cmd");
+		Files.writeString(source.resolve("jbang.ps1"), "new ps1");
+		Files.writeString(source.resolve("jbang.jar"), "new jar");
+		Files.writeString(target.resolve("jbang.cmd"), "running cmd");
+		Files.writeString(target.resolve("jbang.jar"), "running jar");
+		environmentVariables.set(Util.JBANG_RUNTIME_SHELL, "cmd");
+
+		App.AppInstall.copyJBangFiles(source, target);
+
+		assertThat(Files.readString(target.resolve("jbang.cmd")), is("running cmd"));
+		assertThat(Files.readString(target.resolve("jbang.cmd.new")), is("new cmd"));
+		assertThat(Files.readString(target.resolve("jbang")), is("new sh"));
+		assertThat(Files.readString(target.resolve("jbang.ps1")), is("new ps1"));
+		assertThat(Files.readString(target.resolve("jbang.jar")), is("running jar"));
+		assertThat(Files.readString(target.resolve("jbang.jar.new")), is("new jar"));
+
+		String updateCommand = App.AppInstall.cmdLauncherUpdateCommand();
+		assertThat(updateCommand, notNullValue());
+		Process process = new ProcessBuilder("cmd", "/d", "/c", updateCommand).start();
+		assertThat(process.waitFor(), is(0));
+		assertThat(Files.readString(target.resolve("jbang.cmd")), is("new cmd"));
+		assertThat(target.resolve("jbang.cmd.new").toFile(), not(anExistingFile()));
+	}
+
+	@Test
+	@EnabledOnOs(OS.WINDOWS)
+	void testUpdateReplacesStagedCmdLauncherOutsideCmd(@TempDir Path tempDir) throws IOException {
+		Path source = Files.createDirectory(tempDir.resolve("source"));
+		Path target = Files.createDirectory(tempDir.resolve("target"));
+		Files.writeString(source.resolve("jbang"), "new sh");
+		Files.writeString(source.resolve("jbang.cmd"), "new cmd");
+		Files.writeString(source.resolve("jbang.ps1"), "new ps1");
+		Files.writeString(source.resolve("jbang.jar"), "new jar");
+		Files.writeString(target.resolve("jbang.cmd"), "old cmd");
+		environmentVariables.set(Util.JBANG_RUNTIME_SHELL, "powershell");
+
+		App.AppInstall.copyJBangFiles(source, target);
+
+		assertThat(Files.readString(target.resolve("jbang.cmd")), is("new cmd"));
+		assertThat(target.resolve("jbang.cmd.new").toFile(), not(anExistingFile()));
+	}
+
 	@Test
 	void testAppInstallFile() throws Exception {
 		String src = examplesTestFolder.resolve("with space/helloworld.java").toString();

src/test/java/dev/jbang/cli/TestPowerShellSelfUpdate.java

@@ -0,0 +1,83 @@
+package dev.jbang.cli;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.jar.Attributes;
+import java.util.jar.JarEntry;
+import java.util.jar.JarOutputStream;
+import java.util.jar.Manifest;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.EnabledOnOs;
+import org.junit.jupiter.api.condition.OS;
+
+@EnabledOnOs(OS.WINDOWS)
+class TestPowerShellSelfUpdate extends AbstractScriptTest {
+
+	@BeforeEach
+	void checkPowerShell() {
+		requirePowerShell();
+	}
+
+	@Test
+	void replacesRunningPowerShellLauncher() throws Exception {
+		Path binDir = Files.createDirectories(tempDir.resolve("bin"));
+		Path launcher = binDir.resolve("jbang.ps1");
+		Files.copy(PS1_SCRIPT, launcher);
+		createUpdaterJar(binDir.resolve("jbang.jar"));
+
+		Map<String, String> env = new HashMap<>(System.getenv());
+		env.put("JAVA_HOME", System.getProperty("java.home"));
+		env.put("JBANG_DIR", tempDir.resolve("jbang-home").toString());
+		env.put("JBANG_CACHE_DIR", tempDir.resolve("cache").toString());
+		env.put("JBANG_NO_VERSION_CHECK", "true");
+
+		List<String> command = new ArrayList<>();
+		command.add(psCommand);
+		command.add("-NoProfile");
+		command.add("-ExecutionPolicy");
+		command.add("Bypass");
+		command.add("-File");
+		command.add(launcher.toString());
+		RunResult result = runProcess(command, env);
+
+		assertEquals(0, result.exitCode, result.stderr);
+		assertEquals("# updated while running\n", Files.readString(launcher).replace("\r\n", "\n"));
+		assertFalse(Files.exists(launcher.resolveSibling("jbang.ps1.new")));
+	}
+
+	private static void createUpdaterJar(Path jar) throws IOException {
+		Manifest manifest = new Manifest();
+		manifest.getMainAttributes().put(Attributes.Name.MANIFEST_VERSION, "1.0");
+		manifest.getMainAttributes().put(Attributes.Name.MAIN_CLASS, PowerShellUpdater.class.getName());
+		String classResource = PowerShellUpdater.class.getName().replace('.', '/') + ".class";
+		try (InputStream input = PowerShellUpdater.class.getClassLoader().getResourceAsStream(classResource);
+				JarOutputStream output = new JarOutputStream(Files.newOutputStream(jar), manifest)) {
+			if (input == null) {
+				throw new IOException("Could not find test updater class: " + classResource);
+			}
+			output.putNextEntry(new JarEntry(classResource));
+			input.transferTo(output);
+			output.closeEntry();
+		}
+	}
+
+	public static class PowerShellUpdater {
+		public static void main(String[] args) throws IOException {
+			Path launcher = Paths.get(System.getenv("JBANG_LAUNCH_CMD"));
+			Files.write(launcher, "# updated while running\n".getBytes(StandardCharsets.UTF_8));
+		}
+	}
+}