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 *
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>
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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 jdk.internal.module.ModulePath;
46 import jdk.internal.module.SystemModuleFinder;
47 import sun.security.action.GetPropertyAction;
48
49 /**
50 * A finder of modules. A {@code ModuleFinder} is used to find modules during
51 * <a href="Configuration.html#resolution">resolution</a> or
52 * <a href="Configuration.html#servicebinding">service binding</a>.
53 *
54 * <p> A {@code ModuleFinder} can only find one module with a given name. A
55 * {@code ModuleFinder} that finds modules in a sequence of directories, for
56 * example, will locate the first occurrence of a module of a given name and
57 * will ignore other modules of that name that appear in directories later in
58 * the sequence. </p>
59 *
60 * <p> Example usage: </p>
61 *
62 * <pre>{@code
63 * Path dir1, dir2, dir3;
64 *
65 * ModuleFinder finder = ModuleFinder.of(dir1, dir2, dir3);
66 *
122 * ModuleReference} element in the returned set then it is guaranteed that
123 * {@link #find find} will locate the {@code ModuleReference} if invoked
124 * to find that module. </p>
125 *
126 * @apiNote This is important to have for methods such as {@link
127 * Configuration#resolveRequiresAndUses resolveRequiresAndUses} that need
128 * to scan the module path to find modules that provide a specific service.
129 *
130 * @return The set of all module references that this finder locates
131 *
132 * @throws FindException
133 * If an error occurs finding all modules
134 *
135 * @throws SecurityException
136 * If denied by the security manager
137 */
138 Set<ModuleReference> findAll();
139
140 /**
141 * Returns a module finder that locates the <em>system modules</em>. The
142 * system modules are the modules in the Java run-time image.
143 * The module finder will always find {@code java.base}.
144 *
145 * <p> If there is a security manager set then its {@link
146 * SecurityManager#checkPermission(Permission) checkPermission} method is
147 * invoked to check that the caller has been granted {@link FilePermission}
148 * to recursively read the directory that is the value of the system
149 * property {@code java.home}. </p>
150 *
151 * @return A {@code ModuleFinder} that locates the system modules
152 *
153 * @throws SecurityException
154 * If denied by the security manager
155 */
156 static ModuleFinder ofSystem() {
157 String home;
158
159 SecurityManager sm = System.getSecurityManager();
160 if (sm != null) {
161 PrivilegedAction<String> pa = new GetPropertyAction("java.home");
162 home = AccessController.doPrivileged(pa);
163 Permission p = new FilePermission(home + File.separator + "-", "read");
164 sm.checkPermission(p);
165 } else {
166 home = System.getProperty("java.home");
167 }
168
169 Path modules = Paths.get(home, "lib", "modules");
170 if (Files.isRegularFile(modules)) {
171 return SystemModuleFinder.getInstance();
172 } else {
173 Path mlib = Paths.get(home, "modules");
174 if (Files.isDirectory(mlib)) {
175 return of(mlib);
176 } else {
177 throw new InternalError("Unable to detect the run-time image");
178 }
179 }
180 }
181
182 /**
183 * Returns a module finder that locates modules on the file system by
184 * searching a sequence of directories and/or packaged modules.
185 *
186 * Each element in the given array is one of:
187 * <ol>
188 * <li><p> A path to a directory of modules.</p></li>
189 * <li><p> A path to the <em>top-level</em> directory of an
190 * <em>exploded module</em>. </p></li>
191 * <li><p> A path to a <em>packaged module</em>. </p></li>
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