1 /*
2 * Copyright (c) 2015, 2024, 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 UNNAMED_MODULE = jla.defineUnnamedModule(null);
65 jla.addEnableNativeAccess(UNNAMED_MODULE);
66 setBootLoaderUnnamedModule0(UNNAMED_MODULE);
67 }
68
69 // ClassLoaderValue map for the boot class loader
70 private static final ConcurrentHashMap<?, ?> CLASS_LOADER_VALUE_MAP
71 = new ConcurrentHashMap<>();
72
73 // native libraries loaded by the boot class loader
74 private static final NativeLibraries NATIVE_LIBS
75 = NativeLibraries.newInstance(null);
76
77 /**
78 * Returns the unnamed module for the boot loader.
79 */
80 public static Module getUnnamedModule() {
81 return UNNAMED_MODULE;
82 }
83
84 /**
85 * Returns the ServiceCatalog for modules defined to the boot class loader.
86 */
87 public static ServicesCatalog getServicesCatalog() {
88 return ServicesCatalog.getServicesCatalog(ClassLoaders.bootLoader());
89 }
90
91 /**
92 * Returns the ClassLoaderValue map for the boot class loader.
93 */
94 public static ConcurrentHashMap<?, ?> getClassLoaderValueMap() {
95 return CLASS_LOADER_VALUE_MAP;
96 }
97
98 /**
99 * Returns NativeLibraries for the boot class loader.
100 */
101 public static NativeLibraries getNativeLibraries() {
102 return NATIVE_LIBS;
103 }
104
105 /**
106 * Returns {@code true} if there is a class path associated with the
107 * BootLoader.
108 */
109 public static boolean hasClassPath() {
110 return ClassLoaders.bootLoader().hasClassPath();
111 }
112
113 /**
114 * Registers a module with this class loader so that its classes
115 * (and resources) become visible via this class loader.
116 */
117 public static void loadModule(ModuleReference mref) {
118 ClassLoaders.bootLoader().loadModule(mref);
119 }
120
121 /**
122 * Loads the Class object with the given name defined to the boot loader.
123 */
124 public static Class<?> loadClassOrNull(String name) {
125 return JLA.findBootstrapClassOrNull(name);
126 }
127
128 /**
129 * Loads the Class object with the given name in the given module
130 * defined to the boot loader. Returns {@code null} if not found.
131 */
132 public static Class<?> loadClass(Module module, String name) {
133 Class<?> c = loadClassOrNull(name);
134 if (c != null && c.getModule() == module) {
135 return c;
136 } else {
137 return null;
138 }
139 }
140
141 /**
142 * Loads a native library from the system library path.
143 */
144 public static void loadLibrary(String name) {
145 getNativeLibraries().loadLibrary(name);
146 }
147
148 /**
149 * Returns a URL to a resource in a module defined to the boot loader.
150 */
151 public static URL findResource(String mn, String name) throws IOException {
152 return ClassLoaders.bootLoader().findResource(mn, name);
153 }
154
155 /**
156 * Returns an input stream to a resource in a module defined to the
157 * boot loader.
158 */
159 public static InputStream findResourceAsStream(String mn, String name)
160 throws IOException
161 {
162 return ClassLoaders.bootLoader().findResourceAsStream(mn, name);
163 }
164
165 /**
166 * Returns the URL to the given resource in any of the modules
167 * defined to the boot loader and the boot class path.
168 */
169 public static URL findResource(String name) {
170 return ClassLoaders.bootLoader().findResource(name);
171 }
172
173 /**
174 * Returns an Iterator to iterate over the resources of the given name
175 * in any of the modules defined to the boot loader.
176 */
177 public static Enumeration<URL> findResources(String name) throws IOException {
178 return ClassLoaders.bootLoader().findResources(name);
179 }
180
181 /**
182 * Define a package for the given class to the boot loader, if not already
183 * defined.
184 */
185 public static Package definePackage(Class<?> c) {
186 return getDefinedPackage(c.getPackageName());
187 }
188
189 /**
190 * Returns the Package of the given name defined to the boot loader or null
191 * if the package has not been defined.
192 */
193 public static Package getDefinedPackage(String pn) {
194 Package pkg = ClassLoaders.bootLoader().getDefinedPackage(pn);
195 if (pkg == null) {
196 String location = getSystemPackageLocation(pn.replace('.', '/'));
197 if (location != null) {
198 pkg = PackageHelper.definePackage(pn.intern(), location);
199 }
200 }
201 return pkg;
202 }
203
204 /**
205 * Returns a stream of the packages defined to the boot loader.
206 */
207 public static Stream<Package> packages() {
208 return Arrays.stream(getSystemPackageNames())
209 .map(name -> getDefinedPackage(name.replace('/', '.')));
210 }
211
212 /**
213 * Helper class to define {@code Package} objects for packages in modules
214 * defined to the boot loader.
215 */
216 static class PackageHelper {
217 private static final JavaLangAccess JLA = SharedSecrets.getJavaLangAccess();
218
219 /**
220 * Define the {@code Package} with the given name. The specified
221 * location is a jrt URL to a named module in the run-time image,
222 * a file URL to a module in an exploded run-time image, or a file
223 * path to an entry on the boot class path (java agent Boot-Class-Path
224 * or -Xbootclasspath/a.
225 *
226 * <p> If the given location is a JAR file containing a manifest,
227 * the defined Package contains the versioning information from
228 * the manifest, if present.
229 *
230 * @param name package name
231 * @param location location where the package is (jrt URL or file URL
232 * for a named module in the run-time or exploded image;
233 * a file path for a package from -Xbootclasspath/a)
234 */
235 static Package definePackage(String name, String location) {
236 Module module = findModule(location);
237 if (module != null) {
238 // named module from runtime image or exploded module
239 if (name.isEmpty())
240 throw new InternalError("empty package in " + location);
241 return JLA.definePackage(ClassLoaders.bootLoader(), name, module);
242 }
243
244 // package in unnamed module (-Xbootclasspath/a)
245 URL url = toFileURL(location);
246 Manifest man = url != null ? getManifest(location) : null;
247
248 return ClassLoaders.bootLoader().defineOrCheckPackage(name, man, url);
249 }
250
251 /**
252 * Finds the module at the given location defined to the boot loader.
253 * The module is either in runtime image or exploded image.
254 * Otherwise this method returns null.
255 */
256 private static Module findModule(String location) {
257 String mn = null;
258 if (location.startsWith("jrt:/")) {
259 // named module in runtime image ("jrt:/".length() == 5)
260 mn = location.substring(5, location.length());
261 } else if (location.startsWith("file:/")) {
262 // named module in exploded image
263 Path path = Path.of(URI.create(location));
264 Path modulesDir = Path.of(JAVA_HOME, "modules");
265 if (path.startsWith(modulesDir)) {
266 mn = path.getFileName().toString();
267 }
268 }
269
270 // return the Module object for the module name. The Module may
271 // in the boot layer or a child layer for the case that the module
272 // is loaded into a running VM
273 if (mn != null) {
274 String name = mn;
275 return Modules.findLoadedModule(mn)
276 .orElseThrow(() -> new InternalError(name + " not loaded"));
277 } else {
278 return null;
279 }
280 }
281
282 /**
283 * Returns URL if the given location is a regular file path.
284 */
285 private static URL toFileURL(String location) {
286 Path path = Path.of(location);
287 if (Files.isRegularFile(path)) {
288 try {
289 return path.toUri().toURL();
290 } catch (MalformedURLException e) {}
291 }
292 return null;
293 }
294
295 /**
296 * Returns the Manifest if the given location is a JAR file
297 * containing a manifest.
298 */
299 private static Manifest getManifest(String location) {
300 Path jar = Path.of(location);
301 try (InputStream in = Files.newInputStream(jar);
302 JarInputStream jis = new JarInputStream(in, false)) {
303 return jis.getManifest();
304 } catch (IOException e) {
305 return null;
306 }
307 }
308 }
309
310 /**
311 * Returns an array of the binary name of the packages defined by
312 * the boot loader, in VM internal form (forward slashes instead of dot).
313 */
314 private static native String[] getSystemPackageNames();
315
316 /**
317 * Returns the location of the package of the given name, if
318 * defined by the boot loader; otherwise {@code null} is returned.
319 *
320 * The location may be a module from the runtime image or exploded image,
321 * or from the boot class append path (i.e. -Xbootclasspath/a or
322 * BOOT-CLASS-PATH attribute specified in java agent).
323 */
324 private static native String getSystemPackageLocation(String name);
325 private static native void setBootLoaderUnnamedModule0(Module module);
326 }