Shorten long working directories of launched processes on Windows

Fixes eclipse-pde/eclipse.pde#1333

Author: HannesWell

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

@@ -21,7 +21,7 @@ Export-Package: org.eclipse.debug.core,
 Require-Bundle: org.eclipse.core.resources;bundle-version="[3.18.0,4.0.0)";visibility:=reexport,
  org.eclipse.core.variables;bundle-version="[3.2.800,4.0.0)",
  org.eclipse.core.runtime;bundle-version="[3.29.0,4.0.0)",
- org.eclipse.core.filesystem;bundle-version="[1.2.0,2.0.0)",
+ org.eclipse.core.filesystem;bundle-version="[1.11.0,2.0.0)",
  org.eclipse.core.expressions;bundle-version="[3.4.0,4.0.0)"
 Bundle-ActivationPolicy: lazy
 Bundle-RequiredExecutionEnvironment: JavaSE-17

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

@@ -990,7 +990,9 @@ public static Process exec(String[] cmdLine, File workingDirectory, String[] env
 			// builder to not break existing caller of this method
 			if (mergeOutput) {
 				ProcessBuilder pb = new ProcessBuilder(cmdLine);
-				pb.directory(workingDirectory);
+				if (workingDirectory != null) {
+					pb.directory(shortenWindowsPath(workingDirectory));
+				}
 				pb.redirectErrorStream(mergeOutput);
 				if (envp != null) {
 					Map<String, String> env = pb.environment();
@@ -1006,7 +1008,7 @@ public static Process exec(String[] cmdLine, File workingDirectory, String[] env
 			} else if (workingDirectory == null) {
 				p = Runtime.getRuntime().exec(cmdLine, envp);
 			} else {
-				p = Runtime.getRuntime().exec(cmdLine, envp, workingDirectory);
+				p = Runtime.getRuntime().exec(cmdLine, envp, shortenWindowsPath(workingDirectory));
 			}
 		} catch (IOException e) {
 			Status status = new Status(IStatus.ERROR, getUniqueIdentifier(), ERROR, DebugCoreMessages.DebugPlugin_0, e);
@@ -1018,14 +1020,36 @@ public static Process exec(String[] cmdLine, File workingDirectory, String[] env
 
 			if (handler != null) {
 				Object result = handler.handleStatus(status, null);
-				if (result instanceof Boolean && ((Boolean) result).booleanValue()) {
+				if (result instanceof Boolean resultValue && resultValue) {
 					p = exec(cmdLine, null);
 				}
 			}
 		}
 		return p;
 	}
 
+	// https://learn.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation
+	private static final int WINDOWS_MAX_PATH = 258;
+
+	private static File shortenWindowsPath(File path) {
+		if (path.getPath().length() > WINDOWS_MAX_PATH && Platform.OS.isWindows()) {
+			// When spawning new processes on Windows, there is no uniform way
+			// to use long working directory paths that exceed the default path
+			// length limit, like for example using the raw path prefix '\\?\'
+			// See https://bugs.openjdk.org/browse/JDK-8315405
+			// The best we can do is trying to shorten the path and hope that
+			// it becomes sufficiently short.
+			@SuppressWarnings("restriction")
+			String shortPath = org.eclipse.core.internal.filesystem.local.Win32Handler.getShortPathName(path.toString());
+			if (shortPath != null) {
+				return new File(shortPath);
+			} else {
+				log(Status.warning("Working directory of process to create exceeds Window's MAX_PATH limit and shortening the path failed.")); //$NON-NLS-1$
+			}
+		}
+		return path;
+	}
+
 	/**
 	 * Returns whether this plug-in is in the process of
 	 * being shutdown.

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

@@ -13,26 +13,38 @@
  *******************************************************************************/
 package org.eclipse.debug.tests.launching;
 
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.IOException;
 import java.lang.reflect.InvocationHandler;
 import java.lang.reflect.Proxy;
+import java.util.Collections;
 import java.util.ConcurrentModificationException;
+import java.util.List;
+import java.util.Locale;
 import java.util.concurrent.Semaphore;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.stream.Collectors;
 
+import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IProgressMonitor;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Status;
 import org.eclipse.core.runtime.jobs.Job;
+import org.eclipse.debug.core.DebugPlugin;
 import org.eclipse.debug.core.ILaunchManager;
 import org.eclipse.debug.core.Launch;
 import org.eclipse.debug.core.model.IDebugTarget;
 import org.eclipse.debug.core.model.IDisconnect;
 import org.eclipse.debug.core.model.IProcess;
 import org.junit.Before;
+import org.junit.ClassRule;
 import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
 
 /**
  * Tests for the {@link Launch} class
@@ -124,6 +136,30 @@ public void testDisconnectedAndWriteProcesses() throws Exception {
 		assertTrue(testExecution(readIsDisconnectedTask, writeProcessesTask));
 	}
 
+	@ClassRule
+	public static TemporaryFolder tempFolder = new TemporaryFolder();
+
+	@Test
+	public void testProcessLaunchWithLongWorkingDirectory() throws CoreException, IOException {
+		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);
+		File workingDirectory = tempFolder.newFolder(segments);
+		assertTrue(workingDirectory.toString().length() > 300);
+
+		startProcessAndAssertOutputContains(List.of("java", "--version"), workingDirectory, false, "jdk");
+		startProcessAndAssertOutputContains(List.of("java", "--version"), 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;
+		try (BufferedReader outputReader = new BufferedReader(process.inputReader())) {
+			output = outputReader.lines().collect(Collectors.joining());
+		}
+		assertThat(output.toLowerCase(Locale.ENGLISH)).contains(expectedOutput);
+	}
+
 	private boolean testExecution(final Runnable readTask, final Runnable writeTask) {
 		/*
 		 * Normally 10 times trial is sufficient to reproduce concurrent

resources/bundles/org.eclipse.core.filesystem/src/org/eclipse/core/internal/filesystem/local/Win32Handler.java

@@ -111,6 +111,18 @@ public boolean putFileInfo(String fileName, IFileInfo info, int options) {
 		return FileAPIh.SetFileAttributesW(lpFileName, fileAttributes);
 	}
 
+	public static String getShortPathName(String longPath) {
+		longPath = toLongWindowsPath(longPath);
+		char[] buffer = new char[longPath.length()];
+		// https://learn.microsoft.com/de-de/windows/win32/api/fileapi/nf-fileapi-getshortpathnamew
+		int newLength = com.sun.jna.platform.win32.Kernel32.INSTANCE.GetShortPathName(longPath, buffer, buffer.length);
+		if (0 < newLength && newLength < buffer.length) { // zero means error
+			int offset = longPath.startsWith(WIN32_UNC_RAW_PATH_PREFIX) ? WIN32_UNC_RAW_PATH_PREFIX.length() : WIN32_RAW_PATH_PREFIX.length();
+			return new String(buffer, offset, newLength);
+		}
+		return null;
+	}
+
 	private static String toLongWindowsPath(String fileName) {
 		// See https://learn.microsoft.com/en-us/windows/win32/fileio/naming-a-file
 		if (fileName.startsWith("\\\\") && !fileName.startsWith(WIN32_UNC_RAW_PATH_PREFIX)) { //$NON-NLS-1$