1 /*
2 * Copyright (c) 2015, 2016, 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
26 package jdk.internal.module;
27
28 import java.io.ByteArrayInputStream;
29 import java.io.IOException;
30 import java.io.InputStream;
31 import java.io.UncheckedIOException;
32 import java.lang.module.ModuleDescriptor;
33 import java.lang.module.ModuleFinder;
34 import java.lang.module.ModuleReader;
35 import java.lang.module.ModuleReference;
36 import java.net.URI;
37 import java.net.URLConnection;
38 import java.nio.ByteBuffer;
39 import java.util.ArrayDeque;
40 import java.util.Collections;
41 import java.util.Deque;
42 import java.util.HashMap;
43 import java.util.Iterator;
44 import java.util.Map;
45 import java.util.Map.Entry;
46 import java.util.Objects;
47 import java.util.Optional;
48 import java.util.Set;
49 import java.util.Spliterator;
50 import java.util.function.Consumer;
51 import java.util.function.Supplier;
52 import java.util.stream.Stream;
53 import java.util.stream.StreamSupport;
54
55 import jdk.internal.jimage.ImageLocation;
56 import jdk.internal.jimage.ImageReader;
57 import jdk.internal.jimage.ImageReaderFactory;
58 import jdk.internal.misc.JavaNetUriAccess;
59 import jdk.internal.misc.SharedSecrets;
60 import jdk.internal.module.ModuleHashes.HashSupplier;
61 import jdk.internal.perf.PerfCounter;
62
63 /**
64 * A {@code ModuleFinder} that finds modules that are linked into the
65 * run-time image.
66 *
67 * The modules linked into the run-time image are assumed to have the
68 * Packages attribute.
69 */
70
71 public class SystemModuleFinder implements ModuleFinder {
72
73 private static final JavaNetUriAccess JNUA = SharedSecrets.getJavaNetUriAccess();
74
75 private static final PerfCounter initTime
76 = PerfCounter.newPerfCounter("jdk.module.finder.jimage.initTime");
77 private static final PerfCounter moduleCount
78 = PerfCounter.newPerfCounter("jdk.module.finder.jimage.modules");
79 private static final PerfCounter packageCount
80 = PerfCounter.newPerfCounter("jdk.module.finder.jimage.packages");
81 private static final PerfCounter exportsCount
82 = PerfCounter.newPerfCounter("jdk.module.finder.jimage.exports");
83
84 // singleton finder to find modules in the run-time images
85 private static final SystemModuleFinder INSTANCE;
86
87 public static SystemModuleFinder getInstance() {
88 return INSTANCE;
89 }
90
91 /**
92 * For now, the module references are created eagerly on the assumption
93 * that service binding will require all modules to be located.
94 */
95 static {
96 long t0 = System.nanoTime();
97
98 INSTANCE = new SystemModuleFinder();
99
100 initTime.addElapsedTimeFrom(t0);
101 }
102
103 /**
104 * Holder class for the ImageReader
105 */
106 private static class SystemImage {
107 static final ImageReader READER;
108 static {
109 long t0 = System.nanoTime();
110 READER = ImageReaderFactory.getImageReader();
111 initTime.addElapsedTimeFrom(t0);
112 }
113
114 static ImageReader reader() {
115 return READER;
116 }
117 }
118
119 private static boolean isFastPathSupported() {
120 return SystemModules.MODULE_NAMES.length > 0;
121 }
122
123 private static String[] moduleNames() {
124 if (isFastPathSupported())
125 // module names recorded at link time
126 return SystemModules.MODULE_NAMES;
127
128 // this happens when java.base is patched with java.base
129 // from an exploded image
130 return SystemImage.reader().getModuleNames();
131 }
132
133 // the set of modules in the run-time image
134 private final Set<ModuleReference> modules;
135
136 // maps module name to module reference
137 private final Map<String, ModuleReference> nameToModule;
138
139 // module name to hashes
140 private final Map<String, byte[]> hashes;
141
142 private SystemModuleFinder() {
143 String[] names = moduleNames();
144 int n = names.length;
145 moduleCount.add(n);
146
147 // fastpath is enabled by default.
148 // It can be disabled for troubleshooting purpose.
149 boolean disabled =
150 System.getProperty("jdk.system.module.finder.disabledFastPath") != null;
151
152 ModuleDescriptor[] descriptors;
153 ModuleHashes[] recordedHashes;
154 ModuleResolution[] moduleResolutions;
155
156 // fast loading of ModuleDescriptor of system modules
157 if (isFastPathSupported() && !disabled) {
158 descriptors = SystemModules.descriptors();
159 recordedHashes = SystemModules.hashes();
160 moduleResolutions = SystemModules.moduleResolutions();
161 } else {
162 // if fast loading of ModuleDescriptors is disabled
163 // fallback to read module-info.class
164 descriptors = new ModuleDescriptor[n];
165 recordedHashes = new ModuleHashes[n];
166 moduleResolutions = new ModuleResolution[n];
167 ImageReader imageReader = SystemImage.reader();
168 for (int i = 0; i < names.length; i++) {
169 String mn = names[i];
170 ImageLocation loc = imageReader.findLocation(mn, "module-info.class");
171 ModuleInfo.Attributes attrs =
172 ModuleInfo.read(imageReader.getResourceBuffer(loc), null);
173 descriptors[i] = attrs.descriptor();
174 recordedHashes[i] = attrs.recordedHashes();
175 moduleResolutions[i] = attrs.moduleResolution();
176 }
177 }
178
179 Map<String, byte[]> hashes = null;
180 boolean secondSeen = false;
181 // record the hashes to build HashSupplier
182 for (ModuleHashes mh : recordedHashes) {
183 if (mh != null) {
184 // if only one module contain ModuleHashes, use it
185 if (hashes == null) {
186 hashes = mh.hashes();
187 } else {
188 if (!secondSeen) {
189 hashes = new HashMap<>(hashes);
190 secondSeen = true;
191 }
192 hashes.putAll(mh.hashes());
193 }
194 }
195 }
196 this.hashes = (hashes == null) ? Map.of() : hashes;
197
198 ModuleReference[] mods = new ModuleReference[n];
199
200 @SuppressWarnings(value = {"rawtypes", "unchecked"})
201 Entry<String, ModuleReference>[] map
202 = (Entry<String, ModuleReference>[])new Entry[n];
203
204 for (int i = 0; i < n; i++) {
205 ModuleDescriptor md = descriptors[i];
206
207 // create the ModuleReference
208 ModuleReference mref = toModuleReference(md,
209 recordedHashes[i],
210 hashSupplier(names[i]),
211 moduleResolutions[i]);
212 mods[i] = mref;
213 map[i] = Map.entry(names[i], mref);
214
215 // counters
216 packageCount.add(md.packages().size());
217 exportsCount.add(md.exports().size());
218 }
219
220 modules = Set.of(mods);
221 nameToModule = Map.ofEntries(map);
222 }
223
224 @Override
225 public Optional<ModuleReference> find(String name) {
226 Objects.requireNonNull(name);
227 return Optional.ofNullable(nameToModule.get(name));
228 }
229
230 @Override
231 public Set<ModuleReference> findAll() {
232 return modules;
233 }
234
235 private ModuleReference toModuleReference(ModuleDescriptor md,
236 ModuleHashes recordedHashes,
237 HashSupplier hasher,
238 ModuleResolution mres) {
239 String mn = md.name();
240 URI uri = JNUA.create("jrt", "/".concat(mn));
241
242 Supplier<ModuleReader> readerSupplier = new Supplier<>() {
243 @Override
244 public ModuleReader get() {
245 return new ImageModuleReader(mn, uri);
246 }
247 };
248
249 ModuleReference mref =
250 new ModuleReferenceImpl(md, uri, readerSupplier, null,
251 recordedHashes, hasher, mres);
252
253 // may need a reference to a patched module if --patch-module specified
254 mref = ModuleBootstrap.patcher().patchIfNeeded(mref);
255
256 return mref;
257 }
258
259 private HashSupplier hashSupplier(String name) {
260 if (!hashes.containsKey(name))
261 return null;
262
263 return new HashSupplier() {
264 @Override
265 public byte[] generate(String algorithm) {
266 return hashes.get(name);
267 }
268 };
269 }
270
271 /**
272 * A ModuleReader for reading resources from a module linked into the
273 * run-time image.
274 */
275 static class ImageModuleReader implements ModuleReader {
276 private final String module;
277 private volatile boolean closed;
278
279 /**
280 * If there is a security manager set then check permission to
281 * connect to the run-time image.
282 */
283 private static void checkPermissionToConnect(URI uri) {
284 SecurityManager sm = System.getSecurityManager();
285 if (sm != null) {
286 try {
287 URLConnection uc = uri.toURL().openConnection();
288 sm.checkPermission(uc.getPermission());
289 } catch (IOException ioe) {
290 throw new UncheckedIOException(ioe);
291 }
292 }
293 }
294
295 ImageModuleReader(String module, URI uri) {
296 checkPermissionToConnect(uri);
297 this.module = module;
298 }
299
300 /**
301 * Returns the ImageLocation for the given resource, {@code null}
302 * if not found.
303 */
304 private ImageLocation findImageLocation(String name) throws IOException {
305 Objects.requireNonNull(name);
306 if (closed)
307 throw new IOException("ModuleReader is closed");
308 ImageReader imageReader = SystemImage.reader();
309 if (imageReader != null) {
310 return imageReader.findLocation(module, name);
311 } else {
312 // not an images build
313 return null;
314 }
315 }
316
317 @Override
318 public Optional<URI> find(String name) throws IOException {
319 ImageLocation location = findImageLocation(name);
320 if (location != null) {
321 URI u = URI.create("jrt:/" + module + "/" + name);
322 return Optional.of(u);
323 } else {
324 return Optional.empty();
325 }
326 }
327
328 @Override
329 public Optional<InputStream> open(String name) throws IOException {
330 return read(name).map(this::toInputStream);
331 }
332
333 private InputStream toInputStream(ByteBuffer bb) { // ## -> ByteBuffer?
334 try {
335 int rem = bb.remaining();
336 byte[] bytes = new byte[rem];
337 bb.get(bytes);
338 return new ByteArrayInputStream(bytes);
339 } finally {
340 release(bb);
341 }
342 }
343
344 @Override
345 public Optional<ByteBuffer> read(String name) throws IOException {
346 ImageLocation location = findImageLocation(name);
347 if (location != null) {
348 return Optional.of(SystemImage.reader().getResourceBuffer(location));
349 } else {
350 return Optional.empty();
351 }
352 }
353
354 @Override
355 public void release(ByteBuffer bb) {
356 Objects.requireNonNull(bb);
357 ImageReader.releaseByteBuffer(bb);
358 }
359
360 @Override
361 public Stream<String> list() throws IOException {
362 if (closed)
363 throw new IOException("ModuleReader is closed");
364
365 Spliterator<String> s = new ModuleContentSpliterator(module);
366 return StreamSupport.stream(s, false);
367 }
368
369 @Override
370 public void close() {
371 // nothing else to do
372 closed = true;
373 }
374 }
375
376 /**
377 * A Spliterator for traversing the resources of a module linked into the
378 * run-time image.
379 */
380 static class ModuleContentSpliterator implements Spliterator<String> {
381 final String moduleRoot;
382 final Deque<ImageReader.Node> stack;
383 Iterator<ImageReader.Node> iterator;
384
385 ModuleContentSpliterator(String module) throws IOException {
386 moduleRoot = "/modules/" + module;
387 stack = new ArrayDeque<>();
388
389 // push the root node to the stack to get started
390 ImageReader.Node dir = SystemImage.reader().findNode(moduleRoot);
391 if (dir == null || !dir.isDirectory())
392 throw new IOException(moduleRoot + " not a directory");
393 stack.push(dir);
394 iterator = Collections.emptyIterator();
395 }
396
397 /**
398 * Returns the name of the next non-directory node or {@code null} if
399 * there are no remaining nodes to visit.
400 */
401 private String next() throws IOException {
402 for (;;) {
403 while (iterator.hasNext()) {
404 ImageReader.Node node = iterator.next();
405 String name = node.getName();
406 if (node.isDirectory()) {
407 // build node
408 ImageReader.Node dir = SystemImage.reader().findNode(name);
409 assert dir.isDirectory();
410 stack.push(dir);
411 } else {
412 // strip /modules/$MODULE/ prefix
413 return name.substring(moduleRoot.length() + 1);
414 }
415 }
416
417 if (stack.isEmpty()) {
418 return null;
419 } else {
420 ImageReader.Node dir = stack.poll();
421 assert dir.isDirectory();
422 iterator = dir.getChildren().iterator();
423 }
424 }
425 }
426
427 @Override
428 public boolean tryAdvance(Consumer<? super String> action) {
429 String next;
430 try {
431 next = next();
432 } catch (IOException ioe) {
433 throw new UncheckedIOException(ioe);
434 }
435 if (next != null) {
436 action.accept(next);
437 return true;
438 } else {
439 return false;
440 }
441 }
442
443 @Override
444 public Spliterator<String> trySplit() {
445 return null;
446 }
447
448 @Override
449 public int characteristics() {
450 return Spliterator.DISTINCT + Spliterator.NONNULL + Spliterator.IMMUTABLE;
451 }
452
453 @Override
454 public long estimateSize() {
455 return Long.MAX_VALUE;
456 }
457 }
458 }