/*+
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 * Copyright 2003-2008 Sun Microsystems, Inc.  All Rights Reserved.+
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.+
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 *+
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 * This code is free software; you can redistribute it and/or modify it+
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 * under the terms of the GNU General Public License version 2 only, as+
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 * published by the Free Software Foundation.  Sun designates this+
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 * particular file as subject to the "Classpath" exception as provided+
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 * by Sun in the LICENSE file that accompanied this code.+
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 *+
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 * This code is distributed in the hope that it will be useful, but WITHOUT+
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or+
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License+
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 * version 2 for more details (a copy is included in the LICENSE file that+
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 * accompanied this code).+
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 *+
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 * You should have received a copy of the GNU General Public License version+
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 * 2 along with this work; if not, write to the Free Software Foundation,+
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.+
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 *+
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 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,+
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 * CA 95054 USA or visit www.sun.com if you need additional information or+
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 * have any questions.+
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 */+
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+
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/*+
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 * Copyright 2003 Wily Technology, Inc.+
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 */+
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+
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#include    <jni.h>+
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#include    <jvmti.h>+
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+
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#include    "JPLISAssert.h"+
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#include    "Reentrancy.h"+
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#include    "JPLISAgent.h"+
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+
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/*+
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 *  This module provides some utility functions to support the "same thread" re-entrancy management.+
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 *  Uses JVMTI TLS to store a single bit per thread.+
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 *  Non-zero means the thread is already inside; zero means the thread is not inside.+
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 */+
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+
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/*+
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 *  Local prototypes+
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 */+
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+
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/* Wrapper around set that does the set then re-fetches to make sure it worked.+
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 * Degenerates to a simple set when assertions are disabled.+
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 * This routine is only here because of a bug in the JVMTI where set to 0 fails.+
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 */+
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jvmtiError+
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confirmingTLSSet(   jvmtiEnv *      jvmtienv,+
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                    jthread         thread,+
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                    const void *    newValue);+
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+
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/* Confirmation routine only; used to assure that the TLS slot holds the value we expect it to. */+
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void+
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assertTLSValue( jvmtiEnv *      jvmtienv,+
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                jthread         thread,+
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                const void *    expected);+
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+
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+
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#define JPLIS_CURRENTLY_INSIDE_TOKEN                ((void *) 0x7EFFC0BB)+
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#define JPLIS_CURRENTLY_OUTSIDE_TOKEN               ((void *) 0)+
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+
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+
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jvmtiError+
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confirmingTLSSet(   jvmtiEnv *      jvmtienv,+
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                    jthread         thread,+
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                    const void *    newValue) {+
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    jvmtiError  error;+
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+
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    error = (*jvmtienv)->SetThreadLocalStorage(+
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                                    jvmtienv,+
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                                    thread,+
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                                    newValue);+
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    check_phase_ret_blob(error, error);+
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+
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#if JPLISASSERT_ENABLEASSERTIONS+
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    assertTLSValue( jvmtienv,+
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                    thread,+
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                    newValue);+
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#endif+
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+
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    return error;+
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}+
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+
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void+
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assertTLSValue( jvmtiEnv *      jvmtienv,+
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                jthread         thread,+
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                const void *    expected) {+
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    jvmtiError  error;+
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    void *      test = (void *) 0x99999999;+
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+
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    /* now check if we do a fetch we get what we wrote */+
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    error = (*jvmtienv)->GetThreadLocalStorage(+
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                                jvmtienv,+
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                                thread,+
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                                &test);+
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    check_phase_ret(error);+
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    jplis_assert(error == JVMTI_ERROR_NONE);+
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    jplis_assert(test == expected);+
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}+
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+
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jboolean+
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tryToAcquireReentrancyToken(    jvmtiEnv *  jvmtienv,+
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                                jthread     thread) {+
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    jboolean    result      = JNI_FALSE;+
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    jvmtiError  error       = JVMTI_ERROR_NONE;+
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    void *      storedValue = NULL;+
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+
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    error = (*jvmtienv)->GetThreadLocalStorage(+
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                                jvmtienv,+
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                                thread,+
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                                &storedValue);+
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    check_phase_ret_false(error);+
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    jplis_assert(error == JVMTI_ERROR_NONE);+
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    if ( error == JVMTI_ERROR_NONE ) {+
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        /* if this thread is already inside, just return false and short-circuit */+
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        if ( storedValue == JPLIS_CURRENTLY_INSIDE_TOKEN ) {+
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            result = JNI_FALSE;+
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        }+
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        else {+
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            /* stuff in the sentinel and return true */+
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#if JPLISASSERT_ENABLEASSERTIONS+
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            assertTLSValue( jvmtienv,+
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                            thread,+
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                            JPLIS_CURRENTLY_OUTSIDE_TOKEN);+
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#endif+
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            error = confirmingTLSSet (  jvmtienv,+
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                                        thread,+
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                                        JPLIS_CURRENTLY_INSIDE_TOKEN);+
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            jplis_assert(error == JVMTI_ERROR_NONE);+
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            if ( error != JVMTI_ERROR_NONE ) {+
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                result = JNI_FALSE;+
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            }+
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            else {+
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                result = JNI_TRUE;+
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            }+
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        }+
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    }+
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    return result;+
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}+
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+
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+
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void+
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releaseReentrancyToken(         jvmtiEnv *  jvmtienv,+
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                                jthread     thread)  {+
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    jvmtiError  error       = JVMTI_ERROR_NONE;+
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+
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/* assert we hold the token */+
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#if JPLISASSERT_ENABLEASSERTIONS+
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    assertTLSValue( jvmtienv,+
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                    thread,+
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                    JPLIS_CURRENTLY_INSIDE_TOKEN);+
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#endif+
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+
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    error = confirmingTLSSet(   jvmtienv,+
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                                thread,+
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                                JPLIS_CURRENTLY_OUTSIDE_TOKEN);+
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    jplis_assert(error == JVMTI_ERROR_NONE);+
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+
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}+
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