Handle long executable paths in Windows process launching

Add shortenWindowsCommandLine() to shorten all command line arguments
that exceed Windows MAX_PATH limit, not just the working directory. This
fixes issues where Eclipse is unable to launch processes with long
executable paths on Windows.

The fix uses Windows GetShortPathName API via Win32Handler to convert
long paths to their 8.3 short form before passing them to ProcessBuilder
or Runtime.exec().

Co-authored-by: laeubi <[email protected]>

Version bump(s) for 4.38 stream

Author: Copilot

debug/org.eclipse.debug.core/core/org/eclipse/debug/core/DebugPlugin.java

@@ -1006,6 +1006,7 @@ public static Process exec(String[] cmdLine, File workingDirectory, String[] env
 	public static Process exec(String[] cmdLine, File workingDirectory, String[] envp, boolean mergeOutput) throws CoreException {
 		List<ExecFactoryFacade> factories = DebugPlugin.getDefault().getExecFactories();
 		Optional<File> directory = shortenWindowsPath(workingDirectory);
+		String[] shortenedCmdLine = shortenWindowsCommandLine(cmdLine);
 		Optional<Map<String, String>> envMap = Optional.ofNullable(envp).map(array -> {
 			Map<String, String> map = new LinkedHashMap<>();
 			for (String e : array) {
@@ -1017,7 +1018,7 @@ public static Process exec(String[] cmdLine, File workingDirectory, String[] env
 			return Map.copyOf(map);
 		});
 		for (ExecFactoryFacade holder : factories) {
-			Optional<Process> exec = holder.exec(cmdLine.clone(), directory, envMap, mergeOutput);
+			Optional<Process> exec = holder.exec(shortenedCmdLine.clone(), directory, envMap, mergeOutput);
 			if (exec.isPresent()) {
 				return exec.get();
 			}
@@ -1029,7 +1030,7 @@ public static Process exec(String[] cmdLine, File workingDirectory, String[] env
 			// ProcessBuilder and Runtime.exec only the new option uses process
 			// builder to not break existing caller of this method
 			if (mergeOutput) {
-				ProcessBuilder pb = new ProcessBuilder(cmdLine);
+				ProcessBuilder pb = new ProcessBuilder(shortenedCmdLine);
 				directory.ifPresent(pb::directory);
 				pb.redirectErrorStream(mergeOutput);
 				if (envMap.isPresent()) {
@@ -1039,9 +1040,9 @@ public static Process exec(String[] cmdLine, File workingDirectory, String[] env
 				}
 				return pb.start();
 			} else if (directory.isEmpty()) {
-				return Runtime.getRuntime().exec(cmdLine, envp);
+				return Runtime.getRuntime().exec(shortenedCmdLine, envp);
 			} else {
-				return Runtime.getRuntime().exec(cmdLine, envp, directory.get());
+				return Runtime.getRuntime().exec(shortenedCmdLine, envp, directory.get());
 			}
 		} catch (IOException e) {
 			Status status = new Status(IStatus.ERROR, getUniqueIdentifier(), ERROR, DebugCoreMessages.DebugPlugin_0, e);
@@ -1083,6 +1084,50 @@ private static Optional<File> shortenWindowsPath(File path) {
 		return Optional.ofNullable(path);
 	}
 
+	/**
+	 * Shortens the command line elements if they exceed Windows MAX_PATH limit.
+	 * This is necessary because Windows process creation APIs have problems with
+	 * long paths, even when launching executables or passing file arguments.
+	 *
+	 * @param cmdLine the command line array
+	 * @return the potentially shortened command line array
+	 */
+	private static String[] shortenWindowsCommandLine(String[] cmdLine) {
+		if (cmdLine == null || cmdLine.length == 0 || !Platform.OS.isWindows()) {
+			return cmdLine;
+		}
+
+		String[] result = cmdLine.clone();
+		boolean modified = false;
+
+		// Check and shorten each path-like argument in the command line
+		// The first element is typically the executable path, which is most critical
+		for (int i = 0; i < result.length; i++) {
+			String arg = result[i];
+			if (arg != null && arg.length() > WINDOWS_MAX_PATH) {
+				// Check if this looks like a file path
+				File file = new File(arg);
+				if (file.isAbsolute()) {
+					@SuppressWarnings("restriction")
+					String shortPath = org.eclipse.core.internal.filesystem.local.Win32Handler.getShortPathName(arg);
+					if (shortPath != null) {
+						result[i] = shortPath;
+						modified = true;
+						if (i == 0) {
+							// Log only for the executable (first argument)
+							logDebugMessage("Shortened executable path from " + arg.length() + " to " + shortPath.length() + " characters"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
+						}
+					} else if (i == 0) {
+						// Only warn for the executable path, as that's the most critical
+						log(Status.warning("Executable path exceeds Window's MAX_PATH limit and shortening the path failed: " + arg)); //$NON-NLS-1$
+					}
+				}
+			}
+		}
+
+		return modified ? result : cmdLine;
+	}
+
 	/**
 	 * Returns whether this plug-in is in the process of
 	 * being shutdown.

debug/org.eclipse.debug.tests/META-INF/MANIFEST.MF

@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %pluginName
 Bundle-SymbolicName: org.eclipse.debug.tests;singleton:=true
-Bundle-Version: 3.15.100.qualifier
+Bundle-Version: 3.15.200.qualifier
 Bundle-Localization: plugin
 Require-Bundle: org.eclipse.ui;bundle-version="[3.6.0,4.0.0)",
  org.eclipse.core.runtime;bundle-version="[3.29.0,4.0.0)",

debug/org.eclipse.debug.tests/src/org/eclipse/debug/tests/launching/LaunchTests.java

@@ -20,6 +20,7 @@
 
 import java.io.BufferedReader;
 import java.io.File;
+import java.io.FileOutputStream;
 import java.io.IOException;
 import java.lang.reflect.InvocationHandler;
 import java.lang.reflect.Proxy;
@@ -29,7 +30,9 @@
 import java.util.Locale;
 import java.util.concurrent.Semaphore;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.jar.JarOutputStream;
 import java.util.stream.Collectors;
+import java.util.zip.ZipEntry;
 
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IProgressMonitor;
@@ -55,6 +58,18 @@
  */
 public class LaunchTests extends AbstractLaunchTest {
 
+	/**
+	 * Windows MAX_PATH limit for file paths. See
+	 * https://learn.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation
+	 */
+	private static final int WINDOWS_MAX_PATH = 258;
+
+	/**
+	 * Target length for long path tests. This should be well above MAX_PATH to
+	 * ensure the tests exercise the long path handling code.
+	 */
+	private static final int LONG_PATH_LENGTH_TARGET = 400;
+
 	private InvocationHandler handler;
 	private Runnable readIsTerminatedTask;
 	private Runnable readIsDisconnectedTask;
@@ -146,17 +161,38 @@ public void testProcessLaunchWithLongWorkingDirectory() throws CoreException, IO
 		assumeTrue(Platform.OS.isWindows());
 
 		int rootLength = tempFolder.getRoot().toString().length();
-		String subPathElementsName = "subfolder-with-relativly-long-name";
-		String[] segments = Collections.nCopies((400 - rootLength) / subPathElementsName.length(), subPathElementsName).toArray(String[]::new);
+		String subPathElementsName = "subfolder-with-relatively-long-name";
+		String[] segments = Collections.nCopies((LONG_PATH_LENGTH_TARGET - rootLength) / subPathElementsName.length(), subPathElementsName).toArray(String[]::new);
 		File workingDirectory = tempFolder.newFolder(segments);
-		assertTrue(workingDirectory.toString().length() > 300);
+		assertTrue(workingDirectory.toString().length() > WINDOWS_MAX_PATH);
 
 		// Just launch any process in a directory with a path longer than
 		// Window's MAX_PATH length limit
 		startProcessAndAssertOutputContains(List.of("java", "--version"), workingDirectory, false, "jdk");
 		startProcessAndAssertOutputContains(List.of("java", "--version"), workingDirectory, true, "jdk");
 	}
 
+	@Test
+	public void testProcessLaunchWithLongExecutablePath() throws CoreException, IOException {
+		assumeTrue(Platform.OS.isWindows());
+
+		int rootLength = tempFolder.getRoot().toString().length();
+		String subPathElementsName = "another-one-with-a-long-path-name-2";
+		String[] segments = Collections.nCopies((LONG_PATH_LENGTH_TARGET - rootLength) / subPathElementsName.length(), subPathElementsName).toArray(String[]::new);
+		File workingDirectory = tempFolder.newFolder(segments);
+		assertTrue(workingDirectory.toString().length() > WINDOWS_MAX_PATH);
+		File jar = new File(workingDirectory, "dummy.jar");
+		try (JarOutputStream stream = new JarOutputStream(new FileOutputStream(jar))) {
+			stream.putNextEntry(new ZipEntry("TEST"));
+			stream.write(1);
+		}
+
+		// Just launch any process in a directory with a path longer than
+		// Window's MAX_PATH length limit and an argument that is even longer!
+		startProcessAndAssertOutputContains(List.of("java", "--version", "-cp", jar.getAbsolutePath()), workingDirectory, false, "jdk");
+		startProcessAndAssertOutputContains(List.of("java", "--version", "-cp", jar.getAbsolutePath()), workingDirectory, true, "jdk");
+	}
+
 	private static void startProcessAndAssertOutputContains(List<String> cmdLine, File workingDirectory, boolean mergeOutput, String expectedOutput) throws CoreException, IOException {
 		Process process = DebugPlugin.exec(cmdLine.toArray(String[]::new), workingDirectory, null, mergeOutput);
 		String output;