Fix Windows path handling for nested jars

Update `Path` creation for nested locations to allow both UNC and classic
file references to be used. This commit attempts to align our URL
handling with that of standard file URLs. The `NestedLocation` class
no longer attempts to remove leading all `\` characters and instead
only removes the first `\` when the second char is `:`. This duplicates
the logic found in Java's own internal `WindowsUriSupport` class which
is used when calling `Path.of(url)` with a `file:` URL.

Fixes gh-40549

Author: philwebb

spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/launch/Archive.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -20,6 +20,7 @@
 import java.io.IOException;
 import java.net.URI;
 import java.net.URL;
+import java.nio.file.Path;
 import java.security.CodeSource;
 import java.security.ProtectionDomain;
 import java.util.Set;
@@ -107,11 +108,10 @@ static Archive create(Class<?> target) throws Exception {
 	static Archive create(ProtectionDomain protectionDomain) throws Exception {
 		CodeSource codeSource = protectionDomain.getCodeSource();
 		URI location = (codeSource != null) ? codeSource.getLocation().toURI() : null;
-		String path = (location != null) ? location.getSchemeSpecificPart() : null;
-		if (path == null) {
+		if (location == null) {
 			throw new IllegalStateException("Unable to determine code source archive");
 		}
-		return create(new File(path));
+		return create(Path.of(location).toFile());
 	}
 
 	/**

spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/net/protocol/nested/NestedLocation.java

@@ -53,7 +53,9 @@
  */
 public record NestedLocation(Path path, String nestedEntryName) {
 
-	private static final Map<String, NestedLocation> cache = new ConcurrentHashMap<>();
+	private static final Map<String, NestedLocation> locationCache = new ConcurrentHashMap<>();
+
+	private static final Map<String, Path> pathCache = new ConcurrentHashMap<>();
 
 	public NestedLocation(Path path, String nestedEntryName) {
 		if (path == null) {
@@ -89,35 +91,37 @@ public static NestedLocation fromUri(URI uri) {
 		return parse(uri.getSchemeSpecificPart());
 	}
 
-	static NestedLocation parse(String path) {
-		if (path == null || path.isEmpty()) {
-			throw new IllegalArgumentException("'path' must not be empty");
+	static NestedLocation parse(String location) {
+		if (location == null || location.isEmpty()) {
+			throw new IllegalArgumentException("'location' must not be empty");
 		}
-		int index = path.lastIndexOf("/!");
-		return cache.computeIfAbsent(path, (l) -> create(index, l));
+		return locationCache.computeIfAbsent(location, (key) -> create(location));
 	}
 
-	private static NestedLocation create(int index, String location) {
+	private static NestedLocation create(String location) {
+		int index = location.lastIndexOf("/!");
 		String locationPath = (index != -1) ? location.substring(0, index) : location;
-		if (isWindows() && !isUncPath(location)) {
-			while (locationPath.startsWith("/")) {
-				locationPath = locationPath.substring(1, locationPath.length());
-			}
-		}
 		String nestedEntryName = (index != -1) ? location.substring(index + 2) : null;
-		return new NestedLocation((!locationPath.isEmpty()) ? Path.of(locationPath) : null, nestedEntryName);
+		return new NestedLocation((!locationPath.isEmpty()) ? asPath(locationPath) : null, nestedEntryName);
 	}
 
-	private static boolean isWindows() {
-		return File.separatorChar == '\\';
+	private static Path asPath(String locationPath) {
+		return pathCache.computeIfAbsent(locationPath, (key) -> {
+			if (isWindows() && locationPath.length() > 2 && locationPath.charAt(2) == ':') {
+				// Use the same logic as Java's internal WindowsUriSupport class
+				return Path.of(locationPath.substring(1));
+			}
+			return Path.of(locationPath);
+		});
 	}
 
-	private static boolean isUncPath(String input) {
-		return !input.contains(":");
+	private static boolean isWindows() {
+		return File.separatorChar == '\\';
 	}
 
 	static void clearCache() {
-		cache.clear();
+		locationCache.clear();
+		pathCache.clear();
 	}
 
 }

spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/net/protocol/nested/NestedUrlConnection.java

@@ -38,7 +38,6 @@
 import java.util.Map;
 import java.util.Map.Entry;
 
-import org.springframework.boot.loader.net.util.UrlDecoder;
 import org.springframework.boot.loader.ref.Cleaner;
 
 /**
@@ -77,7 +76,7 @@ class NestedUrlConnection extends URLConnection {
 
 	private NestedLocation parseNestedLocation(URL url) throws MalformedURLException {
 		try {
-			return NestedLocation.parse(UrlDecoder.decode(url.getPath()));
+			return NestedLocation.fromUrl(url);
 		}
 		catch (IllegalArgumentException ex) {
 			throw new MalformedURLException(ex.getMessage());

spring-boot-project/spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/net/protocol/nested/NestedLocationTests.java

@@ -85,7 +85,7 @@ void fromUrlWhenNotNestedProtocolThrowsException() {
 	@Test
 	void fromUrlWhenNoPathThrowsException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> NestedLocation.fromUrl(new URL("nested:")))
-			.withMessageContaining("'path' must not be empty");
+			.withMessageContaining("'location' must not be empty");
 	}
 
 	@Test