1 /*
   2  * Copyright (c) 2015, 2019, 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 java.lang;
  26 
  27 import jdk.internal.access.JavaLangInvokeAccess;
  28 import jdk.internal.access.SharedSecrets;
  29 import jdk.internal.vm.annotation.Stable;
  30 
  31 import java.lang.StackWalker.StackFrame;
  32 import java.lang.invoke.MethodType;
  33 
  34 class StackFrameInfo implements StackFrame {
  35     private final static byte RETAIN_CLASS_REF = 0x01;
  36 
  37     private final static JavaLangInvokeAccess JLIA =
  38         SharedSecrets.getJavaLangInvokeAccess();
  39 
  40     private final byte flags;
  41     private final Object memberName;    // MemberName initialized by VM
  42     private @Stable int bci = -1;       // BCI set by VM
  43     private volatile StackTraceElement ste;
  44 
  45     /*
  46      * Construct an empty StackFrameInfo object that will be filled by the VM
  47      * during stack walking.
  48      *
  49      * @see StackStreamFactory.AbstractStackWalker#callStackWalk
  50      * @see StackStreamFactory.AbstractStackWalker#fetchStackFrames
  51      */
  52     StackFrameInfo(StackWalker walker) {
  53         this.flags = walker.retainClassRef ? RETAIN_CLASS_REF : 0;
  54         this.memberName = JLIA.newMemberName();
  55     }
  56 
  57     // package-private called by StackStreamFactory to skip
  58     // the capability check
  59     Class<?> declaringClass() {
  60         return JLIA.getDeclaringClass(memberName);
  61     }
  62 
  63     // ----- implementation of StackFrame methods
  64 
  65     @Override
  66     public String getClassName() {
  67         return declaringClass().getName();
  68     }
  69 
  70     @Override
  71     public Class<?> getDeclaringClass() {
  72         ensureRetainClassRefEnabled();
  73         return declaringClass();
  74     }
  75 
  76     @Override
  77     public String getMethodName() {
  78         return JLIA.getName(memberName);
  79     }
  80 
  81     @Override
  82     public MethodType getMethodType() {
  83         ensureRetainClassRefEnabled();
  84         return JLIA.getMethodType(memberName);
  85     }
  86 
  87     @Override
  88     public String getDescriptor() {
  89         return JLIA.getMethodDescriptor(memberName);
  90     }
  91 
  92     @Override
  93     public int getByteCodeIndex() {
  94         // bci not available for native methods
  95         if (isNativeMethod())
  96             return -1;
  97 
  98         return bci;
  99     }
 100 
 101     @Override
 102     public String getFileName() {
 103         return toStackTraceElement().getFileName();
 104     }
 105 
 106     @Override
 107     public int getLineNumber() {
 108         // line number not available for native methods
 109         if (isNativeMethod())
 110             return -2;
 111 
 112         return toStackTraceElement().getLineNumber();
 113     }
 114 
 115 
 116     @Override
 117     public boolean isNativeMethod() {
 118         return JLIA.isNative(memberName);
 119     }
 120 
 121     @Override
 122     public String toString() {
 123         return toStackTraceElement().toString();
 124     }
 125 
 126     @Override
 127     public StackTraceElement toStackTraceElement() {
 128         StackTraceElement s = ste;
 129         if (s == null) {
 130             synchronized (this) {
 131                 s = ste;
 132                 if (s == null) {
 133                     ste = s = StackTraceElement.of(this);
 134                 }
 135             }
 136         }
 137         return s;
 138     }
 139 
 140     private void ensureRetainClassRefEnabled() {
 141         if ((flags & RETAIN_CLASS_REF) == 0) {
 142             throw new UnsupportedOperationException("No access to RETAIN_CLASS_REFERENCE");
 143         }
 144     }
 145 }