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.jrtfs;
26
27 import java.io.IOException;
28 import java.io.UncheckedIOException;
29 import java.nio.file.DirectoryStream;
30 import java.nio.file.FileSystemException;
31 import java.nio.file.Files;
32 import java.nio.file.Path;
33 import java.nio.file.attribute.BasicFileAttributes;
34 import java.util.ArrayList;
35 import java.util.HashMap;
36 import java.util.List;
37 import java.util.Map;
38 import java.util.Objects;
39 import java.util.stream.Stream;
40
41 import jdk.internal.jimage.ImageReader.Node;
42
43 /**
44 * A jrt file system built on $JAVA_HOME/modules directory ('exploded modules
45 * build')
46 *
47 * @implNote This class needs to maintain JDK 8 source compatibility.
48 *
49 * It is used internally in the JDK to implement jimage/jrtfs access,
50 * but also compiled and delivered as part of the jrtfs.jar to support access
51 * to the jimage file provided by the shipped JDK by tools running on JDK 8.
52 */
53 class ExplodedImage extends SystemImage {
54
55 private static final String MODULES = "/modules/";
56 private static final String PACKAGES = "/packages/";
57
58 private final Path modulesDir;
59 private final String separator;
60 private final Map<String, PathNode> nodes = new HashMap<>();
61 private final BasicFileAttributes modulesDirAttrs;
62
63 ExplodedImage(Path modulesDir) throws IOException {
64 this.modulesDir = modulesDir;
65 String str = modulesDir.getFileSystem().getSeparator();
66 separator = str.equals("/") ? null : str;
67 modulesDirAttrs = Files.readAttributes(modulesDir, BasicFileAttributes.class);
68 initNodes();
69 }
70
71 // A Node that is backed by actual default file system Path
72 private final class PathNode extends Node {
73
74 // Path in underlying default file system
75 private Path path;
76 private PathNode link;
77 private List<Node> children;
78
79 private PathNode(String name, Path path, BasicFileAttributes attrs) { // path
80 super(name, attrs);
81 this.path = path;
82 }
83
84 private PathNode(String name, Node link) { // link
85 super(name, link.getFileAttributes());
86 this.link = (PathNode)link;
87 }
88
89 private PathNode(String name, List<Node> children) { // dir
90 super(name, modulesDirAttrs);
91 this.children = children;
92 }
93
94 @Override
95 public boolean isResource() {
96 return link == null && !getFileAttributes().isDirectory();
97 }
98
99 @Override
100 public boolean isDirectory() {
101 return children != null ||
102 (link == null && getFileAttributes().isDirectory());
103 }
104
105 @Override
106 public boolean isLink() {
107 return link != null;
108 }
109
110 @Override
111 public PathNode resolveLink(boolean recursive) {
112 if (link == null)
113 return this;
114 return recursive && link.isLink() ? link.resolveLink(true) : link;
115 }
116
117 private byte[] getContent() throws IOException {
118 if (!getFileAttributes().isRegularFile())
119 throw new FileSystemException(getName() + " is not file");
120 return Files.readAllBytes(path);
121 }
122
123 @Override
124 public Stream<String> getChildNames() {
125 if (!isDirectory())
126 throw new IllegalArgumentException("not a directory: " + getName());
127 if (children == null) {
128 List<Node> list = new ArrayList<>();
129 try (DirectoryStream<Path> stream = Files.newDirectoryStream(path)) {
130 for (Path p : stream) {
131 p = modulesDir.relativize(p);
132 String pName = MODULES + nativeSlashToFrontSlash(p.toString());
133 Node node = findNode(pName);
134 if (node != null) { // findNode may choose to hide certain files!
135 list.add(node);
136 }
137 }
138 } catch (IOException x) {
139 return null;
140 }
141 children = list;
142 }
143 return children.stream().map(Node::getName);
144 }
145
146 @Override
147 public long size() {
148 try {
149 return isDirectory() ? 0 : Files.size(path);
150 } catch (IOException ex) {
151 throw new UncheckedIOException(ex);
152 }
153 }
154 }
155
156 @Override
157 public synchronized void close() throws IOException {
158 nodes.clear();
159 }
160
161 @Override
162 public byte[] getResource(Node node) throws IOException {
163 return ((PathNode)node).getContent();
164 }
165
166 @Override
167 public synchronized Node findNode(String name) {
168 PathNode node = nodes.get(name);
169 if (node != null) {
170 return node;
171 }
172 // If null, this was not the name of "/modules/..." node, and since all
173 // "/packages/..." nodes were created and cached in advance, the name
174 // cannot reference a valid node.
175 Path path = underlyingModulesPath(name);
176 if (path == null) {
177 return null;
178 }
179 // This can still return null for hidden files.
180 return createModulesNode(name, path);
181 }
182
183 /**
184 * Lazily creates and caches a {@code Node} for the given "/modules/..." name
185 * and corresponding path to a file or directory.
186 *
187 * @param name a resource or directory node name, of the form "/modules/...".
188 * @param path the path of a file for a resource or directory.
189 * @return the newly created and cached node, or {@code null} if the given
190 * path references a file which must be hidden in the node hierarchy.
191 */
192 private Node createModulesNode(String name, Path path) {
193 assert !nodes.containsKey(name) : "Node must not already exist: " + name;
194 assert isNonEmptyModulesPath(name) : "Invalid modules name: " + name;
195
196 try {
197 // We only know if we're creating a resource of directory when we
198 // look up file attributes, and we only do that once. Thus, we can
199 // only reject "marker files" here, rather than by inspecting the
200 // given name string, since it doesn't apply to directories.
201 BasicFileAttributes attrs = Files.readAttributes(path, BasicFileAttributes.class);
202 if (attrs.isRegularFile()) {
203 Path f = path.getFileName();
204 if (f.toString().startsWith("_the.")) {
205 return null;
206 }
207 } else if (!attrs.isDirectory()) {
208 return null;
209 }
210 PathNode node = new PathNode(name, path, attrs);
211 nodes.put(name, node);
212 return node;
213 } catch (IOException x) {
214 // Since the path reference a file, any errors should not be ignored.
215 throw new UncheckedIOException(x);
216 }
217 }
218
219 /**
220 * Returns the expected file path for name in the "/modules/..." namespace,
221 * or {@code null} if the name is not in the "/modules/..." namespace or the
222 * path does not reference a file.
223 */
224 private Path underlyingModulesPath(String name) {
225 if (isNonEmptyModulesPath(name)) {
226 Path path = modulesDir.resolve(frontSlashToNativeSlash(name.substring(MODULES.length())));
227 return Files.exists(path) ? path : null;
228 }
229 return null;
230 }
231
232 private static boolean isNonEmptyModulesPath(String name) {
233 // Don't just check the prefix, there must be something after it too
234 // (otherwise you end up with an empty string after trimming).
235 return name.startsWith(MODULES) && name.length() > MODULES.length();
236 }
237
238 // convert "/" to platform path separator
239 private String frontSlashToNativeSlash(String str) {
240 return separator == null ? str : str.replace("/", separator);
241 }
242
243 // convert platform path separator to "/"
244 private String nativeSlashToFrontSlash(String str) {
245 return separator == null ? str : str.replace(separator, "/");
246 }
247
248 // convert "/"s to "."s
249 private String slashesToDots(String str) {
250 return str.replace(separator != null ? separator : "/", ".");
251 }
252
253 // initialize file system Nodes
254 private void initNodes() throws IOException {
255 // same package prefix may exist in multiple modules. This Map
256 // is filled by walking "jdk modules" directory recursively!
257 Map<String, List<String>> packageToModules = new HashMap<>();
258 try (DirectoryStream<Path> stream = Files.newDirectoryStream(modulesDir)) {
259 for (Path module : stream) {
260 if (Files.isDirectory(module)) {
261 String moduleName = module.getFileName().toString();
262 // make sure "/modules/<moduleName>" is created
263 Objects.requireNonNull(createModulesNode(MODULES + moduleName, module));
264 try (Stream<Path> contentsStream = Files.walk(module)) {
265 contentsStream.filter(Files::isDirectory).forEach((p) -> {
266 p = module.relativize(p);
267 String pkgName = slashesToDots(p.toString());
268 // skip META-INF and empty strings
269 if (!pkgName.isEmpty() && !pkgName.startsWith("META-INF")) {
270 packageToModules
271 .computeIfAbsent(pkgName, k -> new ArrayList<>())
272 .add(moduleName);
273 }
274 });
275 }
276 }
277 }
278 }
279 // create "/modules" directory
280 // "nodes" map contains only /modules/<foo> nodes only so far and so add all as children of /modules
281 PathNode modulesRootNode = new PathNode("/modules", new ArrayList<>(nodes.values()));
282 nodes.put(modulesRootNode.getName(), modulesRootNode);
283
284 // create children under "/packages"
285 List<Node> packagesChildren = new ArrayList<>(packageToModules.size());
286 for (Map.Entry<String, List<String>> entry : packageToModules.entrySet()) {
287 String pkgName = entry.getKey();
288 List<String> moduleNameList = entry.getValue();
289 List<Node> moduleLinkNodes = new ArrayList<>(moduleNameList.size());
290 for (String moduleName : moduleNameList) {
291 Node moduleNode = Objects.requireNonNull(nodes.get(MODULES + moduleName));
292 PathNode linkNode = new PathNode(PACKAGES + pkgName + "/" + moduleName, moduleNode);
293 nodes.put(linkNode.getName(), linkNode);
294 moduleLinkNodes.add(linkNode);
295 }
296 PathNode pkgDir = new PathNode(PACKAGES + pkgName, moduleLinkNodes);
297 nodes.put(pkgDir.getName(), pkgDir);
298 packagesChildren.add(pkgDir);
299 }
300 // "/packages" dir
301 PathNode packagesRootNode = new PathNode("/packages", packagesChildren);
302 nodes.put(packagesRootNode.getName(), packagesRootNode);
303
304 // finally "/" dir!
305 List<Node> rootChildren = new ArrayList<>();
306 rootChildren.add(packagesRootNode);
307 rootChildren.add(modulesRootNode);
308 PathNode root = new PathNode("/", rootChildren);
309 nodes.put(root.getName(), root);
310 }
311 }