globals.c

/*
 * globals.c: definition and handling of the set of global variables
 *            of the library
 *
 * See Copyright for the status of this software.
 */

#define IN_LIBXML
#include "libxml.h"

#include <stdlib.h>
#include <string.h>

#define XML_GLOBALS_NO_REDEFINITION
#include <libxml/xmlerror.h>
#include <libxml/xmlmemory.h>
#include <libxml/xmlIO.h>
#include <libxml/HTMLparser.h>
#include <libxml/parser.h>
#include <libxml/threads.h>
#include <libxml/tree.h>
#include <libxml/xmlsave.h>
#include <libxml/SAX2.h>

#include "private/dict.h"
#include "private/error.h"
#include "private/globals.h"
#include "private/threads.h"
#include "private/tree.h"

/*
 * Mutex to protect "ForNewThreads" variables
 */
static xmlMutex xmlThrDefMutex;

/*
 * Deprecated global setting which is unused since 2.15.0
 */
static int lineNumbersDefaultValue = 1;

/*
 * Thread-local storage emulation.
 *
 * This works by replacing a global variable
 *
 *     extern xmlError xmlLastError;
 *
 * with a macro that calls a function returning a pointer to the global in
 * thread-local storage:
 *
 *     xmlError *__xmlLastError(void);
 *     #define xmlError (*__xmlLastError());
 *
 * The code can operate in a multitude of ways depending on the environment.
 * First we support POSIX and Windows threads. Then we support both
 * thread-local storage provided by the compiler and older methods like
 * thread-specific data (pthreads) or TlsAlloc (Windows).
 *
 * To clean up thread-local storage, we use thread-specific data on POSIX.
 * On Windows, we either use DllMain when compiling a DLL or a registered
 * wait function for static builds.
 *
 * Compiler TLS isn't really useful for now. It can make allocation more
 * robust on some platforms but it also increases the memory consumption
 * of each thread by ~250 bytes whether it uses libxml2 or not. The main
 * problem is that we have to deallocate strings in xmlLastError and C
 * offers no simple way to deallocate dynamic data in _Thread_local
 * variables. In C++, one could simply use a thread_local variable with a
 * destructor.
 *
 * At some point, many of the deprecated globals can be removed,
 * although things like global error handlers will take a while.
 * Ultimately, the only crucial things seem to be xmlLastError and
 * RNG state. xmlLastError already involves dynamic allocation, so it
 * could be allocated dynamically as well, only storing a global
 * pointer.
 */

#ifdef LIBXML_THREAD_ENABLED

#ifdef HAVE_WIN32_THREADS
  #if defined(LIBXML_STATIC) && !defined(LIBXML_STATIC_FOR_DLL)
    #define USE_WAIT_DTOR
  #else
    #define USE_DLL_MAIN
  #endif
#endif

/*
 * On Darwin, thread-local storage destructors seem to be run before
 * pthread thread-specific data destructors. This causes ASan to
 * report a use-after-free.
 *
 * On Windows, we can't use TLS in static builds. The RegisterWait
 * callback would run after TLS was deallocated.
 */
#if defined(XML_THREAD_LOCAL) && \
    !defined(__APPLE__) && \
    !defined(USE_WAIT_DTOR)
#define USE_TLS
#endif

#ifdef HAVE_POSIX_THREADS

/*
 * On POSIX, we need thread-specific data even with thread-local storage
 * to destroy indirect references from global state (xmlLastError) at
 * thread exit.
 */
static pthread_key_t globalkey;

#elif defined HAVE_WIN32_THREADS

#ifndef USE_TLS
static DWORD globalkey = TLS_OUT_OF_INDEXES;
#endif

#endif /* HAVE_WIN32_THREADS */

static void
xmlFreeGlobalState(void *state);

#endif /* LIBXML_THREAD_ENABLED */

struct _xmlGlobalState {
#ifdef USE_TLS
    int initialized;
#endif

#ifdef USE_WAIT_DTOR
    void *threadHandle;
    void *waitHandle;
#endif

    unsigned localRngState[2];

    xmlError lastError;

#ifdef LIBXML_THREAD_ALLOC_ENABLED
    xmlMallocFunc malloc;
    xmlMallocFunc mallocAtomic;
    xmlReallocFunc realloc;
    xmlFreeFunc free;
    xmlStrdupFunc memStrdup;
#endif

    int doValidityCheckingDefaultValue;
    int getWarningsDefaultValue;
    int keepBlanksDefaultValue;
    int loadExtDtdDefaultValue;
    int pedanticParserDefaultValue;
    int substituteEntitiesDefaultValue;

#ifdef LIBXML_OUTPUT_ENABLED
    int indentTreeOutput;
    const char *treeIndentString;
    int saveNoEmptyTags;
#endif

    xmlGenericErrorFunc genericError;
    void *genericErrorContext;
    xmlStructuredErrorFunc structuredError;
    void *structuredErrorContext;

    xmlRegisterNodeFunc registerNodeDefaultValue;
    xmlDeregisterNodeFunc deregisterNodeDefaultValue;

    xmlParserInputBufferCreateFilenameFunc parserInputBufferCreateFilenameValue;
    xmlOutputBufferCreateFilenameFunc outputBufferCreateFilenameValue;
};

typedef struct _xmlGlobalState xmlGlobalState;
typedef xmlGlobalState *xmlGlobalStatePtr;

#ifdef LIBXML_THREAD_ENABLED

#ifdef USE_TLS
static XML_THREAD_LOCAL xmlGlobalState globalState;
#endif

#else /* LIBXML_THREAD_ENABLED */

static xmlGlobalState globalState;

#endif /* LIBXML_THREAD_ENABLED */

/************************************************************************
 *									*
 *	All the user accessible global variables of the library		*
 *									*
 ************************************************************************/

/**
 * a strdup implementation with a type signature matching POSIX
 *
 * @param cur  the input char *
 * @returns a new xmlChar * or NULL
 */
static char *
xmlPosixStrdup(const char *cur) {
    return((char*) xmlCharStrdup(cur));
}

/*
 * Memory allocation routines
 */

xmlFreeFunc xmlFree = free;
xmlMallocFunc xmlMalloc = malloc;
xmlMallocFunc xmlMallocAtomic = malloc;
xmlReallocFunc xmlRealloc = realloc;
xmlStrdupFunc xmlMemStrdup = xmlPosixStrdup;

/*
 * Parser defaults
 */

static int xmlDoValidityCheckingDefaultValueThrDef = 0;
static int xmlGetWarningsDefaultValueThrDef = 1;
static int xmlLoadExtDtdDefaultValueThrDef = 0;
static int xmlPedanticParserDefaultValueThrDef = 0;
static int xmlKeepBlanksDefaultValueThrDef = 1;
static int xmlSubstituteEntitiesDefaultValueThrDef = 0;

static xmlRegisterNodeFunc xmlRegisterNodeDefaultValueThrDef = NULL;
static xmlDeregisterNodeFunc xmlDeregisterNodeDefaultValueThrDef = NULL;

static xmlParserInputBufferCreateFilenameFunc
xmlParserInputBufferCreateFilenameValueThrDef = NULL;
static xmlOutputBufferCreateFilenameFunc
xmlOutputBufferCreateFilenameValueThrDef = NULL;

static xmlGenericErrorFunc xmlGenericErrorThrDef = xmlGenericErrorDefaultFunc;
static xmlStructuredErrorFunc xmlStructuredErrorThrDef = NULL;
static void *xmlGenericErrorContextThrDef = NULL;
static void *xmlStructuredErrorContextThrDef = NULL;

#ifdef LIBXML_OUTPUT_ENABLED
static int xmlIndentTreeOutputThrDef = 1;
static const char *xmlTreeIndentStringThrDef = "  ";
static int xmlSaveNoEmptyTagsThrDef = 0;
#endif /* LIBXML_OUTPUT_ENABLED */

#ifdef LIBXML_SAX1_ENABLED
/**
 * Default SAX version1 handler for XML, builds the DOM tree
 *
 * @deprecated This handler is unused and will be removed from future
 * versions.
 *
 */
const xmlSAXHandlerV1 xmlDefaultSAXHandler = {
    xmlSAX2InternalSubset,
    xmlSAX2IsStandalone,
    xmlSAX2HasInternalSubset,
    xmlSAX2HasExternalSubset,
    xmlSAX2ResolveEntity,
    xmlSAX2GetEntity,
    xmlSAX2EntityDecl,
    xmlSAX2NotationDecl,
    xmlSAX2AttributeDecl,
    xmlSAX2ElementDecl,
    xmlSAX2UnparsedEntityDecl,
    xmlSAX2SetDocumentLocator,
    xmlSAX2StartDocument,
    xmlSAX2EndDocument,
    xmlSAX2StartElement,
    xmlSAX2EndElement,
    xmlSAX2Reference,
    xmlSAX2Characters,
    xmlSAX2Characters,
    xmlSAX2ProcessingInstruction,
    xmlSAX2Comment,
    xmlParserWarning,
    xmlParserError,
    xmlParserError,
    xmlSAX2GetParameterEntity,
    xmlSAX2CDataBlock,
    xmlSAX2ExternalSubset,
    1,
};
#endif /* LIBXML_SAX1_ENABLED */

/**
 * The default SAX Locator
 * { getPublicId, getSystemId, getLineNumber, getColumnNumber}
 *
 * @deprecated Don't use
 *
 */
const xmlSAXLocator xmlDefaultSAXLocator = {
    xmlSAX2GetPublicId,
    xmlSAX2GetSystemId,
    xmlSAX2GetLineNumber,
    xmlSAX2GetColumnNumber
};

#if defined(LIBXML_HTML_ENABLED) && defined(LIBXML_SAX1_ENABLED)
/**
 * Default old SAX v1 handler for HTML, builds the DOM tree
 *
 * @deprecated This handler is unused and will be removed from future
 * versions.
 *
 */
const xmlSAXHandlerV1 htmlDefaultSAXHandler = {
    xmlSAX2InternalSubset,
    NULL,
    NULL,
    NULL,
    NULL,
    xmlSAX2GetEntity,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    xmlSAX2SetDocumentLocator,
    xmlSAX2StartDocument,
    xmlSAX2EndDocument,
    xmlSAX2StartElement,
    xmlSAX2EndElement,
    NULL,
    xmlSAX2Characters,
    xmlSAX2IgnorableWhitespace,
    xmlSAX2ProcessingInstruction,
    xmlSAX2Comment,
    xmlParserWarning,
    xmlParserError,
    xmlParserError,
    NULL,
    xmlSAX2CDataBlock,
    NULL,
    1,
};
#endif /* LIBXML_HTML_ENABLED */

static void
xmlInitGlobalState(xmlGlobalStatePtr gs);

/************************************************************************
 *									*
 *			Per thread global state handling		*
 *									*
 ************************************************************************/

/**
 * @deprecated Alias for #xmlInitParser.
 */
void xmlInitGlobals(void) {
    xmlInitParser();
}

/**
 * Additional initialisation for multi-threading
 */
void xmlInitGlobalsInternal(void) {
    xmlInitMutex(&xmlThrDefMutex);

#ifdef HAVE_POSIX_THREADS
    pthread_key_create(&globalkey, xmlFreeGlobalState);
#elif defined(HAVE_WIN32_THREADS)
#ifndef USE_TLS
    if (globalkey == TLS_OUT_OF_INDEXES)
        globalkey = TlsAlloc();
#endif
#else /* no thread support */
    xmlInitGlobalState(&globalState);
#endif
}

/**
 * @deprecated This function is a no-op. Call #xmlCleanupParser
 * to free global state but see the warnings there. #xmlCleanupParser
 * should be only called once at program exit. In most cases, you don't
 * have call cleanup functions at all.
 */
void xmlCleanupGlobals(void) {
}

/**
 * Additional cleanup for multi-threading
 */
void xmlCleanupGlobalsInternal(void) {
    /*
     * We assume that all other threads using the library have
     * terminated and the last remaining thread calls
     * xmlCleanupParser.
     */

#ifdef HAVE_POSIX_THREADS
    /*
     * Free thread-specific data of last thread before calling
     * pthread_key_delete.
     */
    xmlGlobalState *gs = pthread_getspecific(globalkey);
    if (gs != NULL)
        xmlFreeGlobalState(gs);
    pthread_key_delete(globalkey);
#elif defined(HAVE_WIN32_THREADS)
#if defined(USE_WAIT_DTOR) && !defined(USE_TLS)
    if (globalkey != TLS_OUT_OF_INDEXES) {
        xmlGlobalState* gs = (xmlGlobalState*)TlsGetValue(globalkey);
        if (gs) {
            /* Unregister the waiter for the thread to terminate, then go ahead
               and free the global state. This avoids false positive reports of
               memory leaks in applications where the main thread created the
               global state; if the registered callback is waiting for the main
               thread to terminate to free the global state, it won't get a
               chance to run.
            */
            if (gs->waitHandle != NULL) {
                UnregisterWait(gs->waitHandle);
                gs->waitHandle = NULL;
            }
           
            if (gs->threadHandle != NULL) {
                CloseHandle(gs->threadHandle);
                gs->threadHandle = NULL;
            }
            
            xmlFreeGlobalState(gs);
            TlsSetValue(globalkey, NULL);
        }
        TlsFree(globalkey);
        globalkey = TLS_OUT_OF_INDEXES;
    }
#endif
#else /* no thread support */
    xmlResetError(&globalState.lastError);
#endif

    xmlCleanupMutex(&xmlThrDefMutex);
}

#ifdef LIBXML_THREAD_ENABLED

static void
xmlFreeGlobalState(void *state)
{
    xmlGlobalState *gs = (xmlGlobalState *) state;

    /*
     * Free any memory allocated in the thread's error struct. If it
     * weren't for this indirect allocation, we wouldn't need
     * a destructor with thread-local storage at all!
     */
    xmlResetError(&gs->lastError);
#ifndef USE_TLS
    free(state);
#endif
}

#if defined(USE_WAIT_DTOR)
static void WINAPI
xmlGlobalStateDtor(void *ctxt, unsigned char timedOut ATTRIBUTE_UNUSED) {
    xmlGlobalStatePtr gs = ctxt;

    UnregisterWait(gs->waitHandle);
    CloseHandle(gs->threadHandle);
    xmlFreeGlobalState(gs);
}

static int
xmlRegisterGlobalStateDtor(xmlGlobalState *gs) {
    void *processHandle = GetCurrentProcess();
    void *threadHandle;
    void *waitHandle;

    if (DuplicateHandle(processHandle, GetCurrentThread(), processHandle,
                &threadHandle, 0, FALSE, DUPLICATE_SAME_ACCESS) == 0) {
        return(-1);
    }

    if (RegisterWaitForSingleObject(&waitHandle, threadHandle,
                xmlGlobalStateDtor, gs, INFINITE, WT_EXECUTEONLYONCE) == 0) {
        CloseHandle(threadHandle);
        return(-1);
    }

    gs->threadHandle = threadHandle;
    gs->waitHandle = waitHandle;
    return(0);
}
#endif /* USE_WAIT_DTOR */

#ifndef USE_TLS
/**
 * Allocates a global state. This structure is used to
 * hold all data for use by a thread when supporting backwards compatibility
 * of libxml2 to pre-thread-safe behaviour.
 *
 * @returns the newly allocated xmlGlobalState or NULL in case of error
 */
static xmlGlobalStatePtr
xmlNewGlobalState(int allowFailure)
{
    xmlGlobalState *gs;

    /*
     * We use malloc/free to allow accessing globals before setting
     * custom memory allocators.
     */
    gs = malloc(sizeof(xmlGlobalState));
    if (gs == NULL) {
        if (allowFailure)
            return(NULL);

        /*
         * If an application didn't call xmlCheckThreadLocalStorage to make
         * sure that global state could be allocated, it's too late to
         * handle the error.
         */
        xmlAbort("libxml2: Failed to allocate globals for thread\n"
                 "libxml2: See xmlCheckThreadLocalStorage\n");
    }

    memset(gs, 0, sizeof(xmlGlobalState));
    xmlInitGlobalState(gs);
    return (gs);
}
#endif

static xmlGlobalStatePtr
xmlGetThreadLocalStorage(int allowFailure) {
    xmlGlobalState *gs;

    (void) allowFailure;

    xmlInitParser();

#ifdef USE_TLS
    gs = &globalState;
    if (gs->initialized == 0)
        xmlInitGlobalState(gs);
#elif defined(HAVE_POSIX_THREADS)
    gs = (xmlGlobalState *) pthread_getspecific(globalkey);
    if (gs == NULL)
        gs = xmlNewGlobalState(allowFailure);
#elif defined(HAVE_WIN32_THREADS)
    gs = (xmlGlobalState *) TlsGetValue(globalkey);
    if (gs == NULL)
        gs = xmlNewGlobalState(allowFailure);
#else
    gs = NULL;
#endif

    return(gs);
}

#else /* LIBXML_THREAD_ENABLED */

static xmlGlobalStatePtr
xmlGetThreadLocalStorage(int allowFailure ATTRIBUTE_UNUSED) {
    return(&globalState);
}

#endif /* LIBXML_THREAD_ENABLED */

static void
xmlInitGlobalState(xmlGlobalStatePtr gs) {
    gs->localRngState[0] = xmlGlobalRandom();
    gs->localRngState[1] = xmlGlobalRandom();

    memset(&gs->lastError, 0, sizeof(xmlError));

#ifdef LIBXML_THREAD_ALLOC_ENABLED
    /* XML_GLOBALS_ALLOC */
    gs->free = free;
    gs->malloc = malloc;
    gs->mallocAtomic = malloc;
    gs->realloc = realloc;
    gs->memStrdup = xmlPosixStrdup;
#endif

    xmlMutexLock(&xmlThrDefMutex);

    /* XML_GLOBALS_PARSER */
    gs->doValidityCheckingDefaultValue =
         xmlDoValidityCheckingDefaultValueThrDef;
    gs->getWarningsDefaultValue = xmlGetWarningsDefaultValueThrDef;
    gs->keepBlanksDefaultValue = xmlKeepBlanksDefaultValueThrDef;
    gs->loadExtDtdDefaultValue = xmlLoadExtDtdDefaultValueThrDef;
    gs->pedanticParserDefaultValue = xmlPedanticParserDefaultValueThrDef;
    gs->substituteEntitiesDefaultValue =
        xmlSubstituteEntitiesDefaultValueThrDef;
#ifdef LIBXML_OUTPUT_ENABLED
    gs->indentTreeOutput = xmlIndentTreeOutputThrDef;
    gs->treeIndentString = xmlTreeIndentStringThrDef;
    gs->saveNoEmptyTags = xmlSaveNoEmptyTagsThrDef;
#endif

    /* XML_GLOBALS_ERROR */
    gs->genericError = xmlGenericErrorThrDef;
    gs->structuredError = xmlStructuredErrorThrDef;
    gs->genericErrorContext = xmlGenericErrorContextThrDef;
    gs->structuredErrorContext = xmlStructuredErrorContextThrDef;

    /* XML_GLOBALS_TREE */
    gs->registerNodeDefaultValue = xmlRegisterNodeDefaultValueThrDef;
    gs->deregisterNodeDefaultValue = xmlDeregisterNodeDefaultValueThrDef;

    /* XML_GLOBALS_IO */
    gs->parserInputBufferCreateFilenameValue =
        xmlParserInputBufferCreateFilenameValueThrDef;
    gs->outputBufferCreateFilenameValue =
        xmlOutputBufferCreateFilenameValueThrDef;

    xmlMutexUnlock(&xmlThrDefMutex);

#ifdef USE_TLS
    gs->initialized = 1;
#endif

#ifdef HAVE_POSIX_THREADS
    pthread_setspecific(globalkey, gs);
#elif defined HAVE_WIN32_THREADS
#ifndef USE_TLS
    TlsSetValue(globalkey, gs);
#endif
#ifdef USE_WAIT_DTOR
    xmlRegisterGlobalStateDtor(gs);
#endif
#endif
}

const xmlError *
__xmlLastError(void) {
    return(&xmlGetThreadLocalStorage(0)->lastError);
}

int *
__xmlDoValidityCheckingDefaultValue(void) {
    return(&xmlGetThreadLocalStorage(0)->doValidityCheckingDefaultValue);
}

int *
__xmlGetWarningsDefaultValue(void) {
    return(&xmlGetThreadLocalStorage(0)->getWarningsDefaultValue);
}

int *
__xmlKeepBlanksDefaultValue(void) {
    return(&xmlGetThreadLocalStorage(0)->keepBlanksDefaultValue);
}

int *
__xmlLineNumbersDefaultValue(void) {
    return(&lineNumbersDefaultValue);
}

int *
__xmlLoadExtDtdDefaultValue(void) {
    return(&xmlGetThreadLocalStorage(0)->loadExtDtdDefaultValue);
}

int *
__xmlPedanticParserDefaultValue(void) {
    return(&xmlGetThreadLocalStorage(0)->pedanticParserDefaultValue);
}

int *
__xmlSubstituteEntitiesDefaultValue(void) {
    return(&xmlGetThreadLocalStorage(0)->substituteEntitiesDefaultValue);
}

#ifdef LIBXML_OUTPUT_ENABLED
int *
__xmlIndentTreeOutput(void) {
    return(&xmlGetThreadLocalStorage(0)->indentTreeOutput);
}

const char **
__xmlTreeIndentString(void) {
    return(&xmlGetThreadLocalStorage(0)->treeIndentString);
}

int *
__xmlSaveNoEmptyTags(void) {
    return(&xmlGetThreadLocalStorage(0)->saveNoEmptyTags);
}
#endif

xmlGenericErrorFunc *
__xmlGenericError(void) {
    return(&xmlGetThreadLocalStorage(0)->genericError);
}

void **
__xmlGenericErrorContext(void) {
    return(&xmlGetThreadLocalStorage(0)->genericErrorContext);
}

xmlStructuredErrorFunc *
__xmlStructuredError(void) {
    return(&xmlGetThreadLocalStorage(0)->structuredError);
}

void **
__xmlStructuredErrorContext(void) {
    return(&xmlGetThreadLocalStorage(0)->structuredErrorContext);
}

xmlRegisterNodeFunc *
__xmlRegisterNodeDefaultValue(void) {
    return(&xmlGetThreadLocalStorage(0)->registerNodeDefaultValue);
}

xmlDeregisterNodeFunc *
__xmlDeregisterNodeDefaultValue(void) {
    return(&xmlGetThreadLocalStorage(0)->deregisterNodeDefaultValue);
}

xmlParserInputBufferCreateFilenameFunc *
__xmlParserInputBufferCreateFilenameValue(void) {
    return(&xmlGetThreadLocalStorage(0)->parserInputBufferCreateFilenameValue);
}

xmlOutputBufferCreateFilenameFunc *
__xmlOutputBufferCreateFilenameValue(void) {
    return(&xmlGetThreadLocalStorage(0)->outputBufferCreateFilenameValue);
}

#ifdef LIBXML_THREAD_ALLOC_ENABLED
xmlMallocFunc *
__xmlMalloc(void) {
    return(&xmlGetThreadLocalStorage(0)->malloc);
}

xmlMallocFunc *
__xmlMallocAtomic(void) {
    return(&xmlGetThreadLocalStorage(0)->mallocAtomic);
}

xmlReallocFunc *
__xmlRealloc(void) {
    return(&xmlGetThreadLocalStorage(0)->realloc);
}

xmlFreeFunc *
__xmlFree(void) {
    return(&xmlGetThreadLocalStorage(0)->free);
}

xmlStrdupFunc *
__xmlMemStrdup(void) {
    return(&xmlGetThreadLocalStorage(0)->memStrdup);
}
#endif /* LIBXML_THREAD_ALLOC_ENABLED */

/**
 * @returns the local RNG state.
 */
unsigned *
xmlGetLocalRngState(void) {
    return(xmlGetThreadLocalStorage(0)->localRngState);
}

/**
 * Check whether thread-local storage could be allocated.
 *
 * In cross-platform code running in multithreaded environments, this
 * function should be called once in each thread before calling other
 * library functions to make sure that thread-local storage was
 * allocated properly.
 *
 * @since 2.12.0
 * @returns 0 on success or -1 if a memory allocation failed. A failed
 * allocation signals a typically fatal and irrecoverable out-of-memory
 * situation. Don't call any library functions in this case.
 */
int
xmlCheckThreadLocalStorage(void) {
#if defined(LIBXML_THREAD_ENABLED) && !defined(USE_TLS)
    if (xmlGetThreadLocalStorage(1) == NULL)
        return(-1);
#endif
    return(0);
}

/**
 * @returns a pointer to the global error struct.
 */
xmlError *
xmlGetLastErrorInternal(void) {
    return(&xmlGetThreadLocalStorage(0)->lastError);
}

#ifdef USE_DLL_MAIN
/**
 * Entry point for Windows library. It is being used to free thread-specific
 * storage.
 *
 * @param hinstDLL  handle to DLL instance
 * @param fdwReason  Reason code for entry
 * @param lpvReserved  generic pointer (depends upon reason code)
 * @returns TRUE always
 */
#if defined(LIBXML_STATIC_FOR_DLL)
int
xmlDllMain(ATTRIBUTE_UNUSED void *hinstDLL, unsigned long fdwReason,
           ATTRIBUTE_UNUSED void *lpvReserved)
#else

/*
 * Declare to avoid "no previous prototype for 'DllMain'" warning.
 *
 * Note that we do NOT want to include this function declaration in
 * a public header because it's meant to be called by Windows itself,
 * not a program that uses this library.
 *
 * It is a mistake to export this function, but changing that seems
 * to break the ABI.
 */
XMLPUBFUN BOOL WINAPI
DllMain (HINSTANCE hinstDLL,
         DWORD     fdwReason,
         LPVOID    lpvReserved);

BOOL WINAPI
DllMain(ATTRIBUTE_UNUSED HINSTANCE hinstDLL, DWORD fdwReason,
        ATTRIBUTE_UNUSED LPVOID lpvReserved)
#endif
{
    if ((fdwReason == DLL_THREAD_DETACH) ||
        (fdwReason == DLL_PROCESS_DETACH)) {
#ifdef USE_TLS
        xmlFreeGlobalState(&globalState);
#else
        if (globalkey != TLS_OUT_OF_INDEXES) {
            xmlGlobalState *globalval;

            globalval = (xmlGlobalState *) TlsGetValue(globalkey);
            if (globalval) {
                xmlFreeGlobalState(globalval);
                TlsSetValue(globalkey, NULL);
            }
        }
#endif
    }

#ifndef LIBXML_THREAD_ALLOC_ENABLED
    if (fdwReason == DLL_PROCESS_DETACH) {
        if (xmlFree == free)
            xmlCleanupParser();
        if (globalkey != TLS_OUT_OF_INDEXES) {
            TlsFree(globalkey);
            globalkey = TLS_OUT_OF_INDEXES;
        }
    }
#endif

    return TRUE;
}
#endif /* USE_DLL_MAIN */

/**
 * Set per-thread default value.
 *
 * @deprecated Call #xmlSetGenericErrorFunc in each thread.
 *
 * @param ctx  user data
 * @param handler  error handler
 */
void
xmlThrDefSetGenericErrorFunc(void *ctx, xmlGenericErrorFunc handler) {
    xmlMutexLock(&xmlThrDefMutex);
    xmlGenericErrorContextThrDef = ctx;
    if (handler != NULL)
	xmlGenericErrorThrDef = handler;
    else
	xmlGenericErrorThrDef = xmlGenericErrorDefaultFunc;
    xmlMutexUnlock(&xmlThrDefMutex);
}

/**
 * Set per-thread default value.
 *
 * @deprecated Call #xmlSetStructuredErrorFunc in each thread.
 *
 * @param ctx  user data
 * @param handler  error handler
 */
void
xmlThrDefSetStructuredErrorFunc(void *ctx, xmlStructuredErrorFunc handler) {
    xmlMutexLock(&xmlThrDefMutex);
    xmlStructuredErrorContextThrDef = ctx;
    xmlStructuredErrorThrDef = handler;
    xmlMutexUnlock(&xmlThrDefMutex);
}

/**
 * Set per-thread default value.
 *
 * @deprecated Use xmlParserOption XML_PARSE_DTDVALID.
 *
 * @param v  new value
 * @returns the old value
 */
int xmlThrDefDoValidityCheckingDefaultValue(int v) {
    int ret;
    xmlMutexLock(&xmlThrDefMutex);
    ret = xmlDoValidityCheckingDefaultValueThrDef;
    xmlDoValidityCheckingDefaultValueThrDef = v;
    xmlMutexUnlock(&xmlThrDefMutex);
    return ret;
}

/**
 * Set per-thread default value.
 *
 * @deprecated Use xmlParserOption XML_PARSE_NOWARNING.
 *
 * @param v  new value
 * @returns the old value
 */
int xmlThrDefGetWarningsDefaultValue(int v) {
    int ret;
    xmlMutexLock(&xmlThrDefMutex);
    ret = xmlGetWarningsDefaultValueThrDef;
    xmlGetWarningsDefaultValueThrDef = v;
    xmlMutexUnlock(&xmlThrDefMutex);
    return ret;
}

#ifdef LIBXML_OUTPUT_ENABLED
/**
 * Set per-thread default value.
 *
 * @deprecated Indenting is enabled by default. Use the xmlsave.h API
 * and xmlSaveOption XML_SAVE_NO_INDENT to disable indenting.
 *
 * @param v  new value
 * @returns the old value
 */
int xmlThrDefIndentTreeOutput(int v) {
    int ret;
    xmlMutexLock(&xmlThrDefMutex);
    ret = xmlIndentTreeOutputThrDef;
    xmlIndentTreeOutputThrDef = v;
    xmlMutexUnlock(&xmlThrDefMutex);
    return ret;
}

/**
 * Set per-thread default value.
 *
 * @deprecated Use the xmlsave.h API and #xmlSaveSetIndentString.
 *
 * @param v  new value
 * @returns the old value
 */
const char * xmlThrDefTreeIndentString(const char * v) {
    const char * ret;
    xmlMutexLock(&xmlThrDefMutex);
    ret = xmlTreeIndentStringThrDef;
    xmlTreeIndentStringThrDef = v;
    xmlMutexUnlock(&xmlThrDefMutex);
    return ret;
}

/**
 * Set per-thread default value.
 *
 * @deprecated Use the xmlsave.h API and xmlSaveOption XML_SAVE_NO_EMPTY.
 *
 * @param v  new value
 * @returns the old value
 */
int xmlThrDefSaveNoEmptyTags(int v) {
    int ret;
    xmlMutexLock(&xmlThrDefMutex);
    ret = xmlSaveNoEmptyTagsThrDef;
    xmlSaveNoEmptyTagsThrDef = v;
    xmlMutexUnlock(&xmlThrDefMutex);
    return ret;
}
#endif

/**
 * Set per-thread default value.
 *
 * @deprecated Whitespace is kept by default. Use xmlParserOption
 * XML_PARSE_NOBLANKS to remove whitespace.
 *
 * @param v  new value
 * @returns the old value
 */
int xmlThrDefKeepBlanksDefaultValue(int v) {
    int ret;
    xmlMutexLock(&xmlThrDefMutex);
    ret = xmlKeepBlanksDefaultValueThrDef;
    xmlKeepBlanksDefaultValueThrDef = v;
    xmlMutexUnlock(&xmlThrDefMutex);
    return ret;
}

/**
 * Set per-thread default value.
 *
 * @deprecated Has no effect.
 *
 * @param v  unused
 * @returns 1
 */
int xmlThrDefLineNumbersDefaultValue(int v ATTRIBUTE_UNUSED) {
    return 1;
}

/**
 * Set per-thread default value.
 *
 * @deprecated Use xmlParserOption XML_PARSE_DTDLOAD.
 *
 * @param v  new value
 * @returns the old value
 */
int xmlThrDefLoadExtDtdDefaultValue(int v) {
    int ret;
    xmlMutexLock(&xmlThrDefMutex);
    ret = xmlLoadExtDtdDefaultValueThrDef;
    xmlLoadExtDtdDefaultValueThrDef = v;
    xmlMutexUnlock(&xmlThrDefMutex);
    return ret;
}

/**
 * Set per-thread default value.
 *
 * @deprecated Use xmlParserOption XML_PARSE_PEDANTIC.
 *
 * @param v  new value
 * @returns the old value
 */
int xmlThrDefPedanticParserDefaultValue(int v) {
    int ret;
    xmlMutexLock(&xmlThrDefMutex);
    ret = xmlPedanticParserDefaultValueThrDef;
    xmlPedanticParserDefaultValueThrDef = v;
    xmlMutexUnlock(&xmlThrDefMutex);
    return ret;
}

/**
 * Set per-thread default value.
 *
 * @deprecated Use xmlParserOption XML_PARSE_NOENT.
 *
 * @param v  new value
 * @returns the old value
 */
int xmlThrDefSubstituteEntitiesDefaultValue(int v) {
    int ret;
    xmlMutexLock(&xmlThrDefMutex);
    ret = xmlSubstituteEntitiesDefaultValueThrDef;
    xmlSubstituteEntitiesDefaultValueThrDef = v;
    xmlMutexUnlock(&xmlThrDefMutex);
    return ret;
}

/**
 * Set per-thread default value.
 *
 * @deprecated This feature will be removed.
 *
 * @param func  new value
 * @returns the old value
 */
xmlRegisterNodeFunc
xmlThrDefRegisterNodeDefault(xmlRegisterNodeFunc func)
{
    xmlRegisterNodeFunc old;

    xmlMutexLock(&xmlThrDefMutex);
    old = xmlRegisterNodeDefaultValueThrDef;

    xmlRegisterCallbacks = 1;
    xmlRegisterNodeDefaultValueThrDef = func;
    xmlMutexUnlock(&xmlThrDefMutex);

    return(old);
}

/**
 * Set per-thread default value.
 *
 * @deprecated This feature will be removed.
 *
 * @param func  new value
 * @returns the old value
 */
xmlDeregisterNodeFunc
xmlThrDefDeregisterNodeDefault(xmlDeregisterNodeFunc func)
{
    xmlDeregisterNodeFunc old;

    xmlMutexLock(&xmlThrDefMutex);
    old = xmlDeregisterNodeDefaultValueThrDef;

    xmlRegisterCallbacks = 1;
    xmlDeregisterNodeDefaultValueThrDef = func;
    xmlMutexUnlock(&xmlThrDefMutex);

    return(old);
}

/**
 * Set per-thread default value.
 *
 * @deprecated Call #xmlParserInputBufferCreateFilenameDefault
 * in each thread.
 *
 * @param func  new value
 * @returns the old value
 */
xmlParserInputBufferCreateFilenameFunc
xmlThrDefParserInputBufferCreateFilenameDefault(xmlParserInputBufferCreateFilenameFunc func)
{
    xmlParserInputBufferCreateFilenameFunc old;

    xmlMutexLock(&xmlThrDefMutex);
    old = xmlParserInputBufferCreateFilenameValueThrDef;
    if (old == NULL) {
		old = __xmlParserInputBufferCreateFilename;
	}

    xmlParserInputBufferCreateFilenameValueThrDef = func;
    xmlMutexUnlock(&xmlThrDefMutex);

    return(old);
}

/**
 * Set per-thread default value.
 *
 * @deprecated Call #xmlOutputBufferCreateFilenameDefault
 * in each thread.
 *
 * @param func  new value
 * @returns the old value
 */
xmlOutputBufferCreateFilenameFunc
xmlThrDefOutputBufferCreateFilenameDefault(xmlOutputBufferCreateFilenameFunc func)
{
    xmlOutputBufferCreateFilenameFunc old;

    xmlMutexLock(&xmlThrDefMutex);
    old = xmlOutputBufferCreateFilenameValueThrDef;
#ifdef LIBXML_OUTPUT_ENABLED
    if (old == NULL) {
		old = __xmlOutputBufferCreateFilename;
	}
#endif
    xmlOutputBufferCreateFilenameValueThrDef = func;
    xmlMutexUnlock(&xmlThrDefMutex);

    return(old);
}