1 /* 2 * Copyright (c) 2014, 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 java.lang.module; 27 28 import java.io.File; 29 import java.io.FilePermission; 30 import java.nio.file.Files; 31 import java.nio.file.Path; 32 import java.nio.file.Paths; 33 import java.security.AccessController; 34 import java.security.Permission; 35 import java.security.PrivilegedAction; 36 import java.util.Collections; 37 import java.util.HashMap; 38 import java.util.HashSet; 39 import java.util.List; 40 import java.util.Map; 41 import java.util.Objects; 42 import java.util.Optional; 43 import java.util.Set; 44 45 import sun.security.action.GetPropertyAction; 46 47 /** 48 * A finder of modules. A {@code ModuleFinder} is used to find modules during 49 * <a href="Configuration.html#resolution">resolution</a> or 50 * <a href="Configuration.html#servicebinding">service binding</a>. 51 * 52 * <p> A {@code ModuleFinder} can only find one module with a given name. A 53 * {@code ModuleFinder} that finds modules in a sequence of directories, for 54 * example, will locate the first occurrence of a module of a given name and 55 * will ignore other modules of that name that appear in directories later in 56 * the sequence. </p> 57 * 58 * <p> Example usage: </p> 59 * 60 * <pre>{@code 61 * Path dir1, dir2, dir3; 62 * 63 * ModuleFinder finder = ModuleFinder.of(dir1, dir2, dir3); 64 * 65 * Optional<ModuleReference> omref = finder.find("jdk.foo"); 66 * omref.ifPresent(mref -> ... ); 67 * 68 * }</pre> 69 * 70 * <p> The {@link #find(String) find} and {@link #findAll() findAll} methods 71 * defined here can fail for several reasons. These include I/O errors, errors 72 * detected parsing a module descriptor ({@code module-info.class}), or in the 73 * case of {@code ModuleFinder} returned by {@link #of ModuleFinder.of}, that 74 * two or more modules with the same name are found in a directory. 75 * When an error is detected then these methods throw {@link FindException 76 * FindException} with an appropriate {@link Throwable#getCause cause}. 77 * The behavior of a {@code ModuleFinder} after a {@code FindException} is 78 * thrown is undefined. For example, invoking {@code find} after an exception 79 * is thrown may or may not scan the same modules that lead to the exception. 80 * It is recommended that a module finder be discarded after an exception is 81 * thrown. </p> 82 * 83 * <p> A {@code ModuleFinder} is not required to be thread safe. </p> 84 * 85 * @since 9 86 */ 87 88 public interface ModuleFinder { 89 90 /** 91 * Finds a reference to a module of a given name. 92 * 93 * <p> A {@code ModuleFinder} provides a consistent view of the 94 * modules that it locates. If {@code find} is invoked several times to 95 * locate the same module (by name) then it will return the same result 96 * each time. If a module is located then it is guaranteed to be a member 97 * of the set of modules returned by the {@link #findAll() findAll} 98 * method. </p> 99 * 100 * @param name 101 * The name of the module to find 102 * 103 * @return A reference to a module with the given name or an empty 104 * {@code Optional} if not found 105 * 106 * @throws FindException 107 * If an error occurs finding the module 108 * 109 * @throws SecurityException 110 * If denied by the security manager 111 */ 112 Optional<ModuleReference> find(String name); 113 114 /** 115 * Returns the set of all module references that this finder can locate. 116 * 117 * <p> A {@code ModuleFinder} provides a consistent view of the modules 118 * that it locates. If {@link #findAll() findAll} is invoked several times 119 * then it will return the same (equals) result each time. For each {@code 120 * ModuleReference} element in the returned set then it is guaranteed that 121 * {@link #find find} will locate the {@code ModuleReference} if invoked 122 * to find that module. </p> 123 * 124 * @apiNote This is important to have for methods such as {@link 125 * Configuration#resolveRequiresAndUses resolveRequiresAndUses} that need 126 * to scan the module path to find modules that provide a specific service. 127 * 128 * @return The set of all module references that this finder locates 129 * 130 * @throws FindException 131 * If an error occurs finding all modules 132 * 133 * @throws SecurityException 134 * If denied by the security manager 135 */ 136 Set<ModuleReference> findAll(); 137 138 /** 139 * Returns a module finder that locates the <em>system modules</em>. The 140 * system modules are typically linked into the Java run-time image. 141 * The module finder will always find {@code java.base}. 142 * 143 * <p> If there is a security manager set then its {@link 144 * SecurityManager#checkPermission(Permission) checkPermission} method is 145 * invoked to check that the caller has been granted {@link FilePermission} 146 * to recursively read the directory that is the value of the system 147 * property {@code java.home}. </p> 148 * 149 * @return A {@code ModuleFinder} that locates the system modules 150 * 151 * @throws SecurityException 152 * If denied by the security manager 153 */ 154 static ModuleFinder ofSystem() { 155 String home; 156 157 SecurityManager sm = System.getSecurityManager(); 158 if (sm != null) { 159 PrivilegedAction<String> pa = new GetPropertyAction("java.home"); 160 home = AccessController.doPrivileged(pa); 161 Permission p = new FilePermission(home + File.separator + "-", "read"); 162 sm.checkPermission(p); 163 } else { 164 home = System.getProperty("java.home"); 165 } 166 167 Path modules = Paths.get(home, "lib", "modules"); 168 if (Files.isRegularFile(modules)) { 169 return new SystemModuleFinder(); 170 } else { 171 Path mlib = Paths.get(home, "modules"); 172 if (Files.isDirectory(mlib)) { 173 return of(mlib); 174 } else { 175 throw new InternalError("Unable to detect the run-time image"); 176 } 177 } 178 } 179 180 /** 181 * Returns a module finder that locates modules on the file system by 182 * searching a sequence of directories and/or packaged modules. 183 * 184 * Each element in the given array is one of: 185 * <ol> 186 * <li><p> A path to a directory of modules.</p></li> 187 * <li><p> A path to the <em>top-level</em> directory of an 188 * <em>exploded module</em>. </p></li> 189 * <li><p> A path to a <em>packaged module</em>. </p></li> 190 * </ol> 191 * 192 * The module finder locates modules by searching each directory, exploded 193 * module, or packaged module in array index order. It finds the first 194 * occurrence of a module with a given name and ignores other modules of 195 * that name that appear later in the sequence. 196 * 197 * <p> If an element is a path to a directory of modules then each entry in 198 * the directory is a packaged module or the top-level directory of an 199 * exploded module. The module finder's {@link #find(String) find} or 200 * {@link #findAll() findAll} methods throw {@link FindException} if a 201 * directory containing more than one module with the same name is 202 * encountered. </p> 203 * 204 * <p> If an element in the array is a path to a directory, and that 205 * directory contains a file named {@code module-info.class}, then the 206 * directory is treated as an exploded module rather than a directory of 207 * modules. </p> 208 * 209 * <p> The module finder returned by this method supports modules that are 210 * packaged as JAR files. A JAR file with a {@code module-info.class} in 211 * the top-level directory of the JAR file (or overridden by a versioned 212 * entry in a {@link java.util.jar.JarFile#isMultiRelease() multi-release} 213 * JAR file) is a modular JAR and is an <em>explicit module</em>. 214 * A JAR file that does not have a {@code module-info.class} in the 215 * top-level directory is an {@link ModuleDescriptor#isAutomatic automatic} 216 * module. The {@link ModuleDescriptor} for an automatic module is created as 217 * follows: 218 * 219 * <ul> 220 * 221 * <li><p> The module {@link ModuleDescriptor#name() name}, and {@link 222 * ModuleDescriptor#version() version} if applicable, is derived from 223 * the file name of the JAR file as follows: </p> 224 * 225 * <ul> 226 * 227 * <li><p> The {@code .jar} suffix is removed. </p></li> 228 * 229 * <li><p> If the name matches the regular expression {@code 230 * "-(\\d+(\\.|$))"} then the module name will be derived from the 231 * subsequence proceeding the hyphen of the first occurrence. The 232 * subsequence after the hyphen is parsed as a {@link 233 * ModuleDescriptor.Version} and ignored if it cannot be parsed as 234 * a {@code Version}. </p></li> 235 * 236 * <li><p> For the module name, then all non-alphanumeric 237 * characters ({@code [^A-Za-z0-9])} are replaced with a dot 238 * ({@code "."}), all repeating dots are replaced with one dot, 239 * and all leading and trailing dots are removed. </p></li> 240 * 241 * <li><p> As an example, a JAR file named {@code foo-bar.jar} will 242 * derive a module name {@code foo.bar} and no version. A JAR file 243 * named {@code foo-1.2.3-SNAPSHOT.jar} will derive a module name 244 * {@code foo} and {@code 1.2.3-SNAPSHOT} as the version. </p></li> 245 * 246 * </ul></li> 247 * 248 * <li><p> It {@link ModuleDescriptor#requires() requires} {@code 249 * java.base}. </p></li> 250 * 251 * <li><p> All entries in the JAR file with names ending with {@code 252 * .class} are assumed to be class files where the name corresponds 253 * to the fully qualified name of the class. The packages of all 254 * classes are {@link ModuleDescriptor#exports() exported}. </p></li> 255 * 256 * <li><p> The contents of all entries starting with {@code 257 * META-INF/services/} are assumed to be service configuration files 258 * (see {@link java.util.ServiceLoader}). The name of the file 259 * (that follows {@code META-INF/services/}) is assumed to be the 260 * fully-qualified binary name of a service type. The entries in the 261 * file are assumed to be the fully-qualified binary names of 262 * provider classes. </p></li> 263 * 264 * <li><p> If the JAR file has a {@code Main-Class} attribute in its 265 * main manifest then its value is the {@link 266 * ModuleDescriptor#mainClass() main class}. </p></li> 267 * 268 * </ul> 269 * 270 * <p> If a {@code ModuleDescriptor} cannot be created (by means of the 271 * {@link ModuleDescriptor.Builder ModuleDescriptor.Builder} API) for an 272 * automatic module then {@code FindException} is thrown. This can arise, 273 * for example, when a legal Java identifier name cannot be derived from 274 * the file name of the JAR file or where a package name derived from an 275 * entry ending with {@code .class} is not a legal Java identifier. </p> 276 * 277 * <p> In addition to JAR files, an implementation may also support modules 278 * that are packaged in other implementation specific module formats. When 279 * a file is encountered that is not recognized as a packaged module then 280 * {@code FindException} is thrown. An implementation may choose to ignore 281 * some files, {@link java.nio.file.Files#isHidden hidden} files for 282 * example. Paths to files that do not exist are always ignored. </p> 283 * 284 * <p> As with automatic modules, the contents of a packaged or exploded 285 * module may need to be <em>scanned</em> in order to determine the packages 286 * in the module. If a {@code .class} file that corresponds to a class in an 287 * unnamed package is encountered then {@code FindException} is thrown. </p> 288 * 289 * <p> Finders created by this method are lazy and do not eagerly check 290 * that the given file paths are directories or packaged modules. 291 * Consequently, the {@code find} or {@code findAll} methods will only 292 * fail if invoking these methods results in searching a directory or 293 * packaged module and an error is encountered. </p> 294 * 295 * @param entries 296 * A possibly-empty array of paths to directories of modules 297 * or paths to packaged or exploded modules 298 * 299 * @return A {@code ModuleFinder} that locates modules on the file system 300 */ 301 static ModuleFinder of(Path... entries) { 302 // special case zero entries 303 if (entries.length == 0) { 304 return new ModuleFinder() { 305 @Override 306 public Optional<ModuleReference> find(String name) { 307 Objects.requireNonNull(name); 308 return Optional.empty(); 309 } 310 311 @Override 312 public Set<ModuleReference> findAll() { 313 return Collections.emptySet(); 314 } 315 }; 316 } 317 318 return new ModulePath(entries); 319 } 320 321 /** 322 * Returns a module finder that is composed from a sequence of zero or more 323 * module finders. The {@link #find(String) find} method of the resulting 324 * module finder will locate a module by invoking the {@code find} method 325 * of each module finder, in array index order, until either the module is 326 * found or all module finders have been searched. The {@link #findAll() 327 * findAll} method of the resulting module finder will return a set of 328 * modules that includes all modules located by the first module finder. 329 * The set of modules will include all modules located by the second or 330 * subsequent module finder that are not located by previous module finders 331 * in the sequence. 332 * 333 * <p> When locating modules then any exceptions or errors thrown by the 334 * {@code find} or {@code findAll} methods of the underlying module finders 335 * will be propogated to the caller of the resulting module finder's 336 * {@code find} or {@code findAll} methods. </p> 337 * 338 * @param finders 339 * The array of module finders 340 * 341 * @return A {@code ModuleFinder} that composes a sequence of module finders 342 */ 343 static ModuleFinder compose(ModuleFinder... finders) { 344 final List<ModuleFinder> finderList = List.of(finders); 345 finderList.forEach(Objects::requireNonNull); 346 347 return new ModuleFinder() { 348 private final Map<String, ModuleReference> nameToModule = new HashMap<>(); 349 private Set<ModuleReference> allModules; 350 351 @Override 352 public Optional<ModuleReference> find(String name) { 353 // cached? 354 ModuleReference mref = nameToModule.get(name); 355 if (mref != null) 356 return Optional.of(mref); 357 Optional<ModuleReference> omref = finderList.stream() 358 .map(f -> f.find(name)) 359 .flatMap(Optional::stream) 360 .findFirst(); 361 omref.ifPresent(m -> nameToModule.put(name, m)); 362 return omref; 363 } 364 365 @Override 366 public Set<ModuleReference> findAll() { 367 if (allModules != null) 368 return allModules; 369 // seed with modules already found 370 Set<ModuleReference> result = new HashSet<>(nameToModule.values()); 371 finderList.stream() 372 .flatMap(f -> f.findAll().stream()) 373 .forEach(mref -> { 374 String name = mref.descriptor().name(); 375 if (nameToModule.putIfAbsent(name, mref) == null) { 376 result.add(mref); 377 } 378 }); 379 allModules = Collections.unmodifiableSet(result); 380 return allModules; 381 } 382 }; 383 } 384 385 }