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jdk/src/java.base/share/classes/java/lang/StackTraceElement.java

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  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;
  27 
  28 import jdk.internal.loader.BuiltinClassLoader;
  29 import jdk.internal.misc.SharedSecrets;
  30 import jdk.internal.misc.VM;
  31 import jdk.internal.module.ModuleHashes;
  32 
  33 import java.lang.module.ModuleDescriptor.Version;
  34 import java.lang.reflect.Layer;
  35 import java.lang.reflect.Module;
  36 import java.util.HashSet;
  37 import java.util.Objects;
  38 import java.util.Optional;
  39 import java.util.Set;
  40 
  41 /**
  42  * An element in a stack trace, as returned by {@link
  43  * Throwable#getStackTrace()}.  Each element represents a single stack frame.
  44  * All stack frames except for the one at the top of the stack represent
  45  * a method invocation.  The frame at the top of the stack represents the
  46  * execution point at which the stack trace was generated.  Typically,
  47  * this is the point at which the throwable corresponding to the stack trace
  48  * was created.
  49  *
  50  * @since  1.4
  51  * @author Josh Bloch
  52  */
  53 public final class StackTraceElement implements java.io.Serializable {
  54     // This field is set to the compacted String representation used
  55     // by StackTraceElement::toString and stored in serial form.


  56     //
  57     // This field is of Object type. VM initially sets this field to
  58     // the Class object of the declaring class to build the compacted string.
  59     private Object classOrLoaderModuleClassName;
  60 
  61     // Normally initialized by VM
  62     private String classLoaderName;
  63     private String moduleName;
  64     private String moduleVersion;
  65     private String declaringClass;
  66     private String methodName;
  67     private String fileName;
  68     private int    lineNumber;

  69 
  70     /**
  71      * Creates a stack trace element representing the specified execution
  72      * point. The {@link #getModuleName module name} and {@link
  73      * #getModuleVersion module version} of the stack trace element will
  74      * be {@code null}.
  75      *
  76      * @param declaringClass the fully qualified name of the class containing
  77      *        the execution point represented by the stack trace element
  78      * @param methodName the name of the method containing the execution point
  79      *        represented by the stack trace element
  80      * @param fileName the name of the file containing the execution point
  81      *         represented by the stack trace element, or {@code null} if
  82      *         this information is unavailable
  83      * @param lineNumber the line number of the source line containing the
  84      *         execution point represented by this stack trace element, or
  85      *         a negative number if this information is unavailable. A value
  86      *         of -2 indicates that the method containing the execution point
  87      *         is a native method
  88      * @throws NullPointerException if {@code declaringClass} or


 239      *
 240      * @return the name of the method containing the execution point
 241      *         represented by this stack trace element.
 242      */
 243     public String getMethodName() {
 244         return methodName;
 245     }
 246 
 247     /**
 248      * Returns true if the method containing the execution point
 249      * represented by this stack trace element is a native method.
 250      *
 251      * @return {@code true} if the method containing the execution point
 252      *         represented by this stack trace element is a native method.
 253      */
 254     public boolean isNativeMethod() {
 255         return lineNumber == -2;
 256     }
 257 
 258     /**
 259      * Returns a string representation of this stack trace element.  The
 260      * format of this string depends on the implementation, but the following
 261      * examples may be regarded as typical:

 262      * <ul>
 263      * <li>
 264      *     "{@code com.foo.loader/foo@9.0/com.foo.Main.run(Main.java:101)}"
 265      * - See the description below.
 266      * </li>
 267      * <li>
 268      *     "{@code com.foo.loader/foo@9.0/com.foo.Main.run(Main.java)}"
 269      * - The line number is unavailable.
 270      * </li>
 271      * <li>
 272      *     "{@code com.foo.loader/foo@9.0/com.foo.Main.run(Unknown Source)}"
 273      * - Neither the file name nor the line number is available.
 274      * </li>
 275      * <li>
 276      *     "{@code com.foo.loader/foo@9.0/com.foo.Main.run(Native Method)}"
 277      * - The method containing the execution point is a native method.
 278      * </li>
 279      * <li>
 280      *     "{@code com.foo.loader//com.foo.bar.App.run(App.java:12)}"
 281      * - The class of the execution point is defined in the unnamed module of


 292      * </li>
 293      * </ul>
 294      *
 295      * <p> The first example shows a stack trace element consisting of
 296      * three elements, each separated by {@code "/"} followed with
 297      * the source file name and the line number of the source line
 298      * containing the execution point.
 299      *
 300      * The first element "{@code com.foo.loader}" is
 301      * the name of the class loader.  The second element "{@code foo@9.0}"
 302      * is the module name and version.  The third element is the method
 303      * containing the execution point; "{@code com.foo.Main"}" is the
 304      * fully-qualified class name and "{@code run}" is the name of the method.
 305      * "{@code Main.java}" is the source file name and "{@code 101}" is
 306      * the line number.
 307      *
 308      * <p> If a class is defined in an <em>unnamed module</em>
 309      * then the second element is omitted as shown in
 310      * "{@code com.foo.loader//com.foo.bar.App.run(App.java:12)}".
 311      *
 312      * If the class loader is a <a href="ClassLoader.html#builtinLoaders">
 313      * built-in class loader</a> or is not named then the first element
 314      * and its following {@code "/"} are omitted as shown in
 315      * "{@code acme@2.1/org.acme.Lib.test(Lib.java:80)}".
 316      * If the first element is omitted and the module is an unnamed module,
 317      * the second element and its following {@code "/"} are also omitted
 318      * as shown in "{@code MyClass.mash(MyClass.java:9)}".
 319      *





 320      * @see    Throwable#printStackTrace()
 321      */
 322     public String toString() {
 323         String s = buildLoaderModuleClassName();
 324         if (s == null) {
 325             // all elements will be included
 326             s = "";
 327             if (classLoaderName != null && !classLoaderName.isEmpty()) {
 328                 s += classLoaderName + "/";
 329             }
 330             if (moduleName != null && !moduleName.isEmpty()) {
 331                 s += moduleName;
 332 
 333                 if (moduleVersion != null && !moduleVersion.isEmpty()) {

 334                     s += "@" + moduleVersion;
 335                 }
 336             }
 337             s = s.isEmpty() ? declaringClass : s + "/" + declaringClass;
 338         }
 339 
 340         return s + "." + methodName + "(" +
 341              (isNativeMethod() ? "Native Method)" :
 342               (fileName != null && lineNumber >= 0 ?
 343                fileName + ":" + lineNumber + ")" :
 344                 (fileName != null ?  ""+fileName+")" : "Unknown Source)")));
 345     }
 346 
 347     /**
 348      * Returns true if the specified object is another
 349      * {@code StackTraceElement} instance representing the same execution
 350      * point as this instance.  Two stack trace elements {@code a} and
 351      * {@code b} are equal if and only if:
 352      * <pre>{@code
 353      *     equals(a.getClassLoaderName(), b.getClassLoaderName()) &&
 354      *     equals(a.getModuleName(), b.getModuleName()) &&
 355      *     equals(a.getModuleVersion(), b.getModuleVersion()) &&
 356      *     equals(a.getClassName(), b.getClassName()) &&
 357      *     equals(a.getMethodName(), b.getMethodName())
 358      *     equals(a.getFileName(), b.getFileName()) &&
 359      *     a.getLineNumber() == b.getLineNumber()
 360      *
 361      * }</pre>
 362      * where {@code equals} has the semantics of {@link
 363      * java.util.Objects#equals(Object, Object) Objects.equals}.
 364      *




 365      * @param  obj the object to be compared with this stack trace element.
 366      * @return true if the specified object is another
 367      *         {@code StackTraceElement} instance representing the same
 368      *         execution point as this instance.
 369      */
 370     public boolean equals(Object obj) {
 371         if (obj==this)
 372             return true;
 373         if (!(obj instanceof StackTraceElement))
 374             return false;
 375         StackTraceElement e = (StackTraceElement)obj;
 376         return Objects.equals(classLoaderName, e.classLoaderName) &&
 377             Objects.equals(moduleName, e.moduleName) &&
 378             Objects.equals(moduleVersion, e.moduleVersion) &&
 379             e.declaringClass.equals(declaringClass) &&
 380             e.lineNumber == lineNumber &&
 381             Objects.equals(methodName, e.methodName) &&
 382             Objects.equals(fileName, e.fileName);
 383     }
 384 
 385     /**
 386      * Returns a hash code value for this stack trace element.
 387      */
 388     public int hashCode() {
 389         int result = 31*declaringClass.hashCode() + methodName.hashCode();
 390         result = 31*result + Objects.hashCode(classLoaderName);
 391         result = 31*result + Objects.hashCode(moduleName);
 392         result = 31*result + Objects.hashCode(moduleVersion);
 393         result = 31*result + Objects.hashCode(fileName);
 394         result = 31*result + lineNumber;
 395         return result;
 396     }
 397 
 398 
 399     /**
 400      * Build the compacted String representation to be returned by
 401      * toString method from the declaring Class object.
 402      */
 403     synchronized String buildLoaderModuleClassName() {
 404         if (classOrLoaderModuleClassName == null)
 405             return null;
 406 
 407         if (classOrLoaderModuleClassName instanceof Class) {
 408             Class<?> cls = (Class<?>)classOrLoaderModuleClassName;
 409             classOrLoaderModuleClassName = toLoaderModuleClassName(cls);
 410         }
 411         return (String)classOrLoaderModuleClassName;
 412     }
 413 
 414     /**
 415      * Returns <loader>/<module>/<fully-qualified-classname> string
 416      * representation of the given class.
 417      * <p>
 418      * If the module is a non-upgradeable JDK module then omit
 419      * its version string.
 420      * <p>
 421      * If the loader has no name, or if the loader is one of the built-in
 422      * loaders (`boot`, `platform`, or `app`) then drop the first element
 423      * (`<loader>/`).
 424      * <p>
 425      * If the first element has been dropped and the module is unnamed
 426      * then drop the second element (`<module>/`).
 427      * <p>
 428      * If the first element is not dropped and the module is unnamed
 429      * then drop `<module>`.
 430      */
 431     private static String toLoaderModuleClassName(Class<?> cls) {
 432         ClassLoader loader = cls.getClassLoader0();
 433         Module m = cls.getModule();

 434 
 435         // First element - class loader name
 436         // Call package-private ClassLoader::name method
 437         String s = "";
 438         if (loader != null && loader.name() != null &&
 439                 !(loader instanceof BuiltinClassLoader)) {
 440             s = loader.name() + "/";
 441         }
 442 
 443         // Second element - module name and version
 444         if (m != null && m.isNamed()) {
 445             s += m.getName();
 446             // Include version if it is a user module or upgradeable module
 447             //
 448             // If it is JDK non-upgradeable module which is recorded
 449             // in the hashes in java.base, omit the version.
 450             if (!isHashedInJavaBase(m)) {
 451                 Optional<Version> ov = m.getDescriptor().version();
 452                 if (ov.isPresent()) {
 453                     String version = "@" + ov.get().toString();
 454                     s += version;
 455                 }




 456             }
 457         }
 458 
 459         // fully-qualified class name
 460         return s.isEmpty() ? cls.getName() : s + "/" + cls.getName();



 461     }
 462 
 463     /**
 464      * Returns true if the module is hashed with java.base.
 465      * <p>
 466      * This method returns false when running on the exploded image
 467      * since JDK modules are not hashed. They have no Version attribute
 468      * and so "@<version>" part will be omitted anyway.
 469      */
 470     private static boolean isHashedInJavaBase(Module m) {
 471         // return true if module system is not initialized as the code
 472         // must be in java.base
 473         if (!VM.isModuleSystemInited())
 474             return true;
 475 
 476         return Layer.boot() == m.getLayer() && HashedModules.contains(m);
 477     }
 478 
 479     /*
 480      * Finds JDK non-upgradeable modules, i.e. the modules that are


 502             return HASHED_MODULES.contains(m.getName());
 503         }
 504     }
 505 
 506 
 507     /*
 508      * Returns an array of StackTraceElements of the given depth
 509      * filled from the backtrace of a given Throwable.
 510      */
 511     static StackTraceElement[] of(Throwable x, int depth) {
 512         StackTraceElement[] stackTrace = new StackTraceElement[depth];
 513         for (int i = 0; i < depth; i++) {
 514             stackTrace[i] = new StackTraceElement();
 515         }
 516 
 517         // VM to fill in StackTraceElement
 518         initStackTraceElements(stackTrace, x);
 519 
 520         // ensure the proper StackTraceElement initialization
 521         for (StackTraceElement ste : stackTrace) {
 522             ste.buildLoaderModuleClassName();
 523         }
 524         return stackTrace;
 525     }
 526 
 527     /*
 528      * Returns a StackTraceElement from a given StackFrameInfo.
 529      */
 530     static StackTraceElement of(StackFrameInfo sfi) {
 531         StackTraceElement ste = new StackTraceElement();
 532         initStackTraceElement(ste, sfi);
 533 
 534         ste.buildLoaderModuleClassName();
 535         return ste;
 536     }
 537 
 538     /*
 539      * Sets the given stack trace elements with the backtrace
 540      * of the given Throwable.
 541      */
 542     private static native void initStackTraceElements(StackTraceElement[] elements,
 543                                                       Throwable x);
 544     /*
 545      * Sets the given stack trace element with the given StackFrameInfo
 546      */
 547     private static native void initStackTraceElement(StackTraceElement element,
 548                                                      StackFrameInfo sfi);
 549 
 550     private static final long serialVersionUID = 6992337162326171013L;
 551 }


  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;
  27 
  28 import jdk.internal.loader.BuiltinClassLoader;
  29 import jdk.internal.misc.SharedSecrets;
  30 import jdk.internal.misc.VM;
  31 import jdk.internal.module.ModuleHashes;
  32 

  33 import java.lang.reflect.Layer;
  34 import java.lang.reflect.Module;
  35 import java.util.HashSet;
  36 import java.util.Objects;
  37 import java.util.Optional;
  38 import java.util.Set;
  39 
  40 /**
  41  * An element in a stack trace, as returned by {@link
  42  * Throwable#getStackTrace()}.  Each element represents a single stack frame.
  43  * All stack frames except for the one at the top of the stack represent
  44  * a method invocation.  The frame at the top of the stack represents the
  45  * execution point at which the stack trace was generated.  Typically,
  46  * this is the point at which the throwable corresponding to the stack trace
  47  * was created.
  48  *
  49  * @since  1.4
  50  * @author Josh Bloch
  51  */
  52 public final class StackTraceElement implements java.io.Serializable {
  53 
  54     // For Throwables and StackWalker, the VM initially sets this field to a
  55     // reference to the declaring Class.  The Class reference is used to 
  56     // construct the 'format' bitmap, and then is cleared.
  57     //
  58     // For STEs constructed using the public constructors, this field is not used.
  59     private transient Class<?> declaringClassObject;

  60 
  61     // Normally initialized by VM
  62     private String classLoaderName;
  63     private String moduleName;
  64     private String moduleVersion;
  65     private String declaringClass;
  66     private String methodName;
  67     private String fileName;
  68     private int    lineNumber;
  69     private byte   format = 0; // Default to show all
  70 
  71     /**
  72      * Creates a stack trace element representing the specified execution
  73      * point. The {@link #getModuleName module name} and {@link
  74      * #getModuleVersion module version} of the stack trace element will
  75      * be {@code null}.
  76      *
  77      * @param declaringClass the fully qualified name of the class containing
  78      *        the execution point represented by the stack trace element
  79      * @param methodName the name of the method containing the execution point
  80      *        represented by the stack trace element
  81      * @param fileName the name of the file containing the execution point
  82      *         represented by the stack trace element, or {@code null} if
  83      *         this information is unavailable
  84      * @param lineNumber the line number of the source line containing the
  85      *         execution point represented by this stack trace element, or
  86      *         a negative number if this information is unavailable. A value
  87      *         of -2 indicates that the method containing the execution point
  88      *         is a native method
  89      * @throws NullPointerException if {@code declaringClass} or


 240      *
 241      * @return the name of the method containing the execution point
 242      *         represented by this stack trace element.
 243      */
 244     public String getMethodName() {
 245         return methodName;
 246     }
 247 
 248     /**
 249      * Returns true if the method containing the execution point
 250      * represented by this stack trace element is a native method.
 251      *
 252      * @return {@code true} if the method containing the execution point
 253      *         represented by this stack trace element is a native method.
 254      */
 255     public boolean isNativeMethod() {
 256         return lineNumber == -2;
 257     }
 258 
 259     /**
 260      * Returns a string representation of this stack trace element.
 261      * 
 262      * @apiNote The format of this string depends on the implementation, but the
 263      * following examples may be regarded as typical:
 264      * <ul>
 265      * <li>
 266      *     "{@code com.foo.loader/foo@9.0/com.foo.Main.run(Main.java:101)}"
 267      * - See the description below.
 268      * </li>
 269      * <li>
 270      *     "{@code com.foo.loader/foo@9.0/com.foo.Main.run(Main.java)}"
 271      * - The line number is unavailable.
 272      * </li>
 273      * <li>
 274      *     "{@code com.foo.loader/foo@9.0/com.foo.Main.run(Unknown Source)}"
 275      * - Neither the file name nor the line number is available.
 276      * </li>
 277      * <li>
 278      *     "{@code com.foo.loader/foo@9.0/com.foo.Main.run(Native Method)}"
 279      * - The method containing the execution point is a native method.
 280      * </li>
 281      * <li>
 282      *     "{@code com.foo.loader//com.foo.bar.App.run(App.java:12)}"
 283      * - The class of the execution point is defined in the unnamed module of


 294      * </li>
 295      * </ul>
 296      *
 297      * <p> The first example shows a stack trace element consisting of
 298      * three elements, each separated by {@code "/"} followed with
 299      * the source file name and the line number of the source line
 300      * containing the execution point.
 301      *
 302      * The first element "{@code com.foo.loader}" is
 303      * the name of the class loader.  The second element "{@code foo@9.0}"
 304      * is the module name and version.  The third element is the method
 305      * containing the execution point; "{@code com.foo.Main"}" is the
 306      * fully-qualified class name and "{@code run}" is the name of the method.
 307      * "{@code Main.java}" is the source file name and "{@code 101}" is
 308      * the line number.
 309      *
 310      * <p> If a class is defined in an <em>unnamed module</em>
 311      * then the second element is omitted as shown in
 312      * "{@code com.foo.loader//com.foo.bar.App.run(App.java:12)}".
 313      *
 314      * <p> If the class loader is a <a href="ClassLoader.html#builtinLoaders">
 315      * built-in class loader</a> or is not named then the first element
 316      * and its following {@code "/"} are omitted as shown in
 317      * "{@code acme@2.1/org.acme.Lib.test(Lib.java:80)}".
 318      * If the first element is omitted and the module is an unnamed module,
 319      * the second element and its following {@code "/"} are also omitted
 320      * as shown in "{@code MyClass.mash(MyClass.java:9)}".
 321      *
 322      * <p> Note that different values can be returned from {@link toString()} for
 323      * StackTraceElements that are otherwise {@linkplain #equals(Object) equal}.
 324      * For instance, the class loader name is omitted for built-in class loaders,
 325      * but not for other class loaders.
 326      *
 327      * @see    Throwable#printStackTrace()
 328      */
 329     public String toString() {
 330         String s = "";
 331         if (!has(BUILTIN_CLASS_LOADER) && classLoaderName != null &&
 332                 !classLoaderName.isEmpty()) {


 333             s += classLoaderName + "/";
 334         }
 335         if (moduleName != null && !moduleName.isEmpty()) {
 336             s += moduleName;
 337 
 338             if (!has(JDK_NON_UPGRADEABLE_MODULE) && moduleVersion != null &&
 339                     !moduleVersion.isEmpty()) {
 340                 s += "@" + moduleVersion;
 341             }
 342         }
 343         s = s.isEmpty() ? declaringClass : s + "/" + declaringClass;

 344 
 345         return s + "." + methodName + "(" +
 346              (isNativeMethod() ? "Native Method)" :
 347               (fileName != null && lineNumber >= 0 ?
 348                fileName + ":" + lineNumber + ")" :
 349                 (fileName != null ?  ""+fileName+")" : "Unknown Source)")));
 350     }
 351 
 352     /**
 353      * Returns true if the specified object is another
 354      * {@code StackTraceElement} instance representing the same execution
 355      * point as this instance.  Two stack trace elements {@code a} and
 356      * {@code b} are equal if and only if:
 357      * <pre>{@code
 358      *     equals(a.getClassLoaderName(), b.getClassLoaderName()) &&
 359      *     equals(a.getModuleName(), b.getModuleName()) &&
 360      *     equals(a.getModuleVersion(), b.getModuleVersion()) &&
 361      *     equals(a.getClassName(), b.getClassName()) &&
 362      *     equals(a.getMethodName(), b.getMethodName())
 363      *     equals(a.getFileName(), b.getFileName()) &&
 364      *     a.getLineNumber() == b.getLineNumber()
 365      *
 366      * }</pre>
 367      * where {@code equals} has the semantics of {@link
 368      * java.util.Objects#equals(Object, Object) Objects.equals}.
 369      *
 370      * @apiNote StackTraceElements can be equal, but return different  
 371      * {@link toString()} values, due to the specifics of how the
 372      * {@link toString()} return value is constructed.
 373      * 
 374      * @param  obj the object to be compared with this stack trace element.
 375      * @return true if the specified object is another
 376      *         {@code StackTraceElement} instance representing the same
 377      *         execution point as this instance.
 378      */
 379     public boolean equals(Object obj) {
 380         if (obj==this)
 381             return true;
 382         if (!(obj instanceof StackTraceElement))
 383             return false;
 384         StackTraceElement e = (StackTraceElement)obj;
 385         return Objects.equals(classLoaderName, e.classLoaderName) &&
 386             Objects.equals(moduleName, e.moduleName) &&
 387             Objects.equals(moduleVersion, e.moduleVersion) &&
 388             e.declaringClass.equals(declaringClass) &&
 389             e.lineNumber == lineNumber &&
 390             Objects.equals(methodName, e.methodName) &&
 391             Objects.equals(fileName, e.fileName);
 392     }
 393 
 394     /**
 395      * Returns a hash code value for this stack trace element.
 396      */
 397     public int hashCode() {
 398         int result = 31*declaringClass.hashCode() + methodName.hashCode();
 399         result = 31*result + Objects.hashCode(classLoaderName);
 400         result = 31*result + Objects.hashCode(moduleName);
 401         result = 31*result + Objects.hashCode(moduleVersion);
 402         result = 31*result + Objects.hashCode(fileName);
 403         result = 31*result + lineNumber;
 404         return result;
 405     }
 406 
 407 
 408     /**
 409      * Called from of() methods to set the 'format' bitmap using the Class
 410      * reference stored in declaringClassObject, and then clear the reference.
 411      */
 412     private synchronized void computeFormat() {
 413         try {
 414             Class<?> cls = (Class<?>) declaringClassObject;


























 415             ClassLoader loader = cls.getClassLoader0();
 416             Module m = cls.getModule();
 417             byte bits = 0;
 418 
 419             // First element - class loader name
 420             // Call package-private ClassLoader::name method
 421 
 422             if (loader instanceof BuiltinClassLoader) {
 423                 bits |= BUILTIN_CLASS_LOADER;

 424             }
 425 
 426             // Second element - module name and version
 427 
 428             // Omit if is a JDK non-upgradeable module (recorded in the hashes
 429             // in java.base)
 430             if (m != null && m.isNamed() &&
 431                     (isHashedInJavaBase(m) || !m.getDescriptor().version().isPresent())) {
 432                 bits |= JDK_NON_UPGRADEABLE_MODULE;





 433             }
 434             format = bits;
 435         } finally {
 436             // Class reference no longer needed, clear it
 437             declaringClassObject = null;
 438         }
 439     }
 440 
 441     private static final byte BUILTIN_CLASS_LOADER       = 0x1;
 442     private static final byte JDK_NON_UPGRADEABLE_MODULE = 0x2;
 443 
 444     private boolean has(byte bit) {
 445         return (format & bit) == bit;
 446     }
 447 
 448     /**
 449      * Returns true if the module is hashed with java.base.
 450      * <p>
 451      * This method returns false when running on the exploded image
 452      * since JDK modules are not hashed. They have no Version attribute
 453      * and so "@<version>" part will be omitted anyway.
 454      */
 455     private static boolean isHashedInJavaBase(Module m) {
 456         // return true if module system is not initialized as the code
 457         // must be in java.base
 458         if (!VM.isModuleSystemInited())
 459             return true;
 460 
 461         return Layer.boot() == m.getLayer() && HashedModules.contains(m);
 462     }
 463 
 464     /*
 465      * Finds JDK non-upgradeable modules, i.e. the modules that are


 487             return HASHED_MODULES.contains(m.getName());
 488         }
 489     }
 490 
 491 
 492     /*
 493      * Returns an array of StackTraceElements of the given depth
 494      * filled from the backtrace of a given Throwable.
 495      */
 496     static StackTraceElement[] of(Throwable x, int depth) {
 497         StackTraceElement[] stackTrace = new StackTraceElement[depth];
 498         for (int i = 0; i < depth; i++) {
 499             stackTrace[i] = new StackTraceElement();
 500         }
 501 
 502         // VM to fill in StackTraceElement
 503         initStackTraceElements(stackTrace, x);
 504 
 505         // ensure the proper StackTraceElement initialization
 506         for (StackTraceElement ste : stackTrace) {
 507             ste.computeFormat();
 508         }
 509         return stackTrace;
 510     }
 511 
 512     /*
 513      * Returns a StackTraceElement from a given StackFrameInfo.
 514      */
 515     static StackTraceElement of(StackFrameInfo sfi) {
 516         StackTraceElement ste = new StackTraceElement();
 517         initStackTraceElement(ste, sfi);
 518 
 519         ste.computeFormat();
 520         return ste;
 521     }
 522 
 523     /*
 524      * Sets the given stack trace elements with the backtrace
 525      * of the given Throwable.
 526      */
 527     private static native void initStackTraceElements(StackTraceElement[] elements,
 528                                                       Throwable x);
 529     /*
 530      * Sets the given stack trace element with the given StackFrameInfo
 531      */
 532     private static native void initStackTraceElement(StackTraceElement element,
 533                                                      StackFrameInfo sfi);
 534 
 535     private static final long serialVersionUID = 6992337162326171013L;
 536 }
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