1 /*
2 * Copyright (c) 2015, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25 package jdk.internal.loader;
26
27 import java.io.IOException;
28 import java.io.InputStream;
29 import java.lang.module.ModuleReference;
30 import java.net.MalformedURLException;
31 import java.net.URI;
32 import java.net.URL;
33 import java.nio.file.Files;
34 import java.nio.file.Path;
35 import java.util.Arrays;
36 import java.util.Enumeration;
37 import java.util.concurrent.ConcurrentHashMap;
38 import java.util.jar.JarInputStream;
39 import java.util.jar.Manifest;
40 import java.util.stream.Stream;
41
42 import jdk.internal.access.JavaLangAccess;
43 import jdk.internal.access.SharedSecrets;
44 import jdk.internal.module.Modules;
45 import jdk.internal.module.ServicesCatalog;
46 import jdk.internal.util.StaticProperty;
47
48 /**
49 * Find resources and packages in modules defined to the boot class loader or
50 * resources and packages on the "boot class path" specified via -Xbootclasspath/a.
51 */
52
53 public class BootLoader {
54 private BootLoader() { }
55
56 private static final JavaLangAccess JLA = SharedSecrets.getJavaLangAccess();
57
58 // The unnamed module for the boot loader
59 private static final Module UNNAMED_MODULE;
60 private static final String JAVA_HOME = StaticProperty.javaHome();
61
62 static {
63 JavaLangAccess jla = SharedSecrets.getJavaLangAccess();
64 ArchivedClassLoaders archivedClassLoaders = ArchivedClassLoaders.get();
65 if (archivedClassLoaders != null) {
66 UNNAMED_MODULE = archivedClassLoaders.unnamedModuleForBootLoader();
67 } else {
68 UNNAMED_MODULE = jla.defineUnnamedModule(null);
69 }
70 jla.addEnableNativeAccess(UNNAMED_MODULE);
71 setBootLoaderUnnamedModule0(UNNAMED_MODULE);
72 }
73
74 // ClassLoaderValue map for the boot class loader
75 private static final ConcurrentHashMap<?, ?> CLASS_LOADER_VALUE_MAP
76 = new ConcurrentHashMap<>();
77
78 // Holder has the field(s) that need to be initialized during JVM bootstrap even if
79 // the outer is aot-initialized.
80 private static class Holder {
81 // native libraries loaded by the boot class loader
82 private static final NativeLibraries NATIVE_LIBS
83 = NativeLibraries.newInstance(null);
84 }
85
86 /**
87 * Returns the unnamed module for the boot loader.
88 */
89 public static Module getUnnamedModule() {
90 return UNNAMED_MODULE;
91 }
92
93 /**
94 * Returns the ServiceCatalog for modules defined to the boot class loader.
95 */
96 public static ServicesCatalog getServicesCatalog() {
97 return ServicesCatalog.getServicesCatalog(ClassLoaders.bootLoader());
98 }
99
100 /**
101 * Returns the ClassLoaderValue map for the boot class loader.
102 */
103 public static ConcurrentHashMap<?, ?> getClassLoaderValueMap() {
104 return CLASS_LOADER_VALUE_MAP;
105 }
106
107 /**
108 * Returns NativeLibraries for the boot class loader.
109 */
110 public static NativeLibraries getNativeLibraries() {
111 return Holder.NATIVE_LIBS;
112 }
113
114 /**
115 * Returns {@code true} if there is a class path associated with the
116 * BootLoader.
117 */
118 public static boolean hasClassPath() {
119 return ClassLoaders.bootLoader().hasClassPath();
120 }
121
122 /**
123 * Registers a module with this class loader so that its classes
124 * (and resources) become visible via this class loader.
125 */
126 public static void loadModule(ModuleReference mref) {
127 ClassLoaders.bootLoader().loadModule(mref);
128 }
129
130 /**
131 * Loads the Class object with the given name defined to the boot loader.
132 */
133 public static Class<?> loadClassOrNull(String name) {
134 return JLA.findBootstrapClassOrNull(name);
135 }
136
137 /**
138 * Loads the Class object with the given name in the given module
139 * defined to the boot loader. Returns {@code null} if not found.
140 */
141 public static Class<?> loadClass(Module module, String name) {
142 Class<?> c = loadClassOrNull(name);
143 if (c != null && c.getModule() == module) {
144 return c;
145 } else {
146 return null;
147 }
148 }
149
150 /**
151 * Loads a native library from the system library path.
152 */
153 public static void loadLibrary(String name) {
154 getNativeLibraries().loadLibrary(name);
155 }
156
157 /**
158 * Returns a URL to a resource in a module defined to the boot loader.
159 */
160 public static URL findResource(String mn, String name) throws IOException {
161 return ClassLoaders.bootLoader().findResource(mn, name);
162 }
163
164 /**
165 * Returns an input stream to a resource in a module defined to the
166 * boot loader.
167 */
168 public static InputStream findResourceAsStream(String mn, String name)
169 throws IOException
170 {
171 return ClassLoaders.bootLoader().findResourceAsStream(mn, name);
172 }
173
174 /**
175 * Returns the URL to the given resource in any of the modules
176 * defined to the boot loader and the boot class path.
177 */
178 public static URL findResource(String name) {
179 return ClassLoaders.bootLoader().findResource(name);
180 }
181
182 /**
183 * Returns an Iterator to iterate over the resources of the given name
184 * in any of the modules defined to the boot loader.
185 */
186 public static Enumeration<URL> findResources(String name) throws IOException {
187 return ClassLoaders.bootLoader().findResources(name);
188 }
189
190 /**
191 * Define a package for the given class to the boot loader, if not already
192 * defined.
193 */
194 public static Package definePackage(Class<?> c) {
195 return getDefinedPackage(c.getPackageName());
196 }
197
198 /**
199 * Returns the Package of the given name defined to the boot loader or null
200 * if the package has not been defined.
201 */
202 public static Package getDefinedPackage(String pn) {
203 Package pkg = ClassLoaders.bootLoader().getDefinedPackage(pn);
204 if (pkg == null) {
205 String location = getSystemPackageLocation(pn.replace('.', '/'));
206 if (location != null) {
207 pkg = PackageHelper.definePackage(pn.intern(), location);
208 }
209 }
210 return pkg;
211 }
212
213 /**
214 * Returns a stream of the packages defined to the boot loader.
215 */
216 public static Stream<Package> packages() {
217 return Arrays.stream(getSystemPackageNames())
218 .map(name -> getDefinedPackage(name.replace('/', '.')));
219 }
220
221 /**
222 * Helper class to define {@code Package} objects for packages in modules
223 * defined to the boot loader.
224 */
225 static class PackageHelper {
226 private static final JavaLangAccess JLA = SharedSecrets.getJavaLangAccess();
227
228 /**
229 * Define the {@code Package} with the given name. The specified
230 * location is a jrt URL to a named module in the run-time image,
231 * a file URL to a module in an exploded run-time image, or a file
232 * path to an entry on the boot class path (java agent Boot-Class-Path
233 * or -Xbootclasspath/a.
234 *
235 * <p> If the given location is a JAR file containing a manifest,
236 * the defined Package contains the versioning information from
237 * the manifest, if present.
238 *
239 * @param name package name
240 * @param location location where the package is (jrt URL or file URL
241 * for a named module in the run-time or exploded image;
242 * a file path for a package from -Xbootclasspath/a)
243 */
244 static Package definePackage(String name, String location) {
245 Module module = findModule(location);
246 if (module != null) {
247 // named module from runtime image or exploded module
248 if (name.isEmpty())
249 throw new InternalError("empty package in " + location);
250 return JLA.definePackage(ClassLoaders.bootLoader(), name, module);
251 }
252
253 // package in unnamed module (-Xbootclasspath/a)
254 URL url = toFileURL(location);
255 Manifest man = url != null ? getManifest(location) : null;
256
257 return ClassLoaders.bootLoader().defineOrCheckPackage(name, man, url);
258 }
259
260 /**
261 * Finds the module at the given location defined to the boot loader.
262 * The module is either in runtime image or exploded image.
263 * Otherwise this method returns null.
264 */
265 private static Module findModule(String location) {
266 String mn = null;
267 if (location.startsWith("jrt:/")) {
268 // named module in runtime image ("jrt:/".length() == 5)
269 mn = location.substring(5, location.length());
270 } else if (location.startsWith("file:/")) {
271 // named module in exploded image
272 Path path = Path.of(URI.create(location));
273 Path modulesDir = Path.of(JAVA_HOME, "modules");
274 if (path.startsWith(modulesDir)) {
275 mn = path.getFileName().toString();
276 }
277 }
278
279 // return the Module object for the module name. The Module may
280 // in the boot layer or a child layer for the case that the module
281 // is loaded into a running VM
282 if (mn != null) {
283 String name = mn;
284 return Modules.findLoadedModule(mn)
285 .orElseThrow(() -> new InternalError(name + " not loaded"));
286 } else {
287 return null;
288 }
289 }
290
291 /**
292 * Returns URL if the given location is a regular file path.
293 */
294 private static URL toFileURL(String location) {
295 Path path = Path.of(location);
296 if (Files.isRegularFile(path)) {
297 try {
298 return path.toUri().toURL();
299 } catch (MalformedURLException e) {}
300 }
301 return null;
302 }
303
304 /**
305 * Returns the Manifest if the given location is a JAR file
306 * containing a manifest.
307 */
308 private static Manifest getManifest(String location) {
309 Path jar = Path.of(location);
310 try (InputStream in = Files.newInputStream(jar);
311 JarInputStream jis = new JarInputStream(in, false)) {
312 return jis.getManifest();
313 } catch (IOException e) {
314 return null;
315 }
316 }
317 }
318
319 /**
320 * Returns an array of the binary name of the packages defined by
321 * the boot loader, in VM internal form (forward slashes instead of dot).
322 */
323 private static native String[] getSystemPackageNames();
324
325 /**
326 * Returns the location of the package of the given name, if
327 * defined by the boot loader; otherwise {@code null} is returned.
328 *
329 * The location may be a module from the runtime image or exploded image,
330 * or from the boot class append path (i.e. -Xbootclasspath/a or
331 * BOOT-CLASS-PATH attribute specified in java agent).
332 */
333 private static native String getSystemPackageLocation(String name);
334 private static native void setBootLoaderUnnamedModule0(Module module);
335 }