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https://gitlab.gnome.org/GNOME/libxml2.git
synced 2025-03-27 18:50:07 +03:00
threads: Use pthread_once and InitOnceExecuteOnce
Static initialization flags aren't thread-safe. Also avoids an allocation on Windows. TODO: Breaks xmllint on Windows.
This commit is contained in:
Nick Wellnhofer
parent
be250b798f
commit
5f3f66c683
@ -3227,6 +3227,7 @@ xmlCatalogCleanup(void) {
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void
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xmlCleanupCatalogInternal(void) {
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xmlFreeRMutex(xmlCatalogMutex);
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xmlCatalogMutex = NULL;
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}
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/**
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12
globals.c
12
globals.c
@ -90,8 +90,6 @@ XML_GLOBALS_TREE
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#undef XML_OP
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};
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static int parserInitialized;
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/*
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* Mutex to protect "ForNewThreads" variables
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*/
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@ -606,8 +604,6 @@ void xmlCleanupGlobalsInternal(void) {
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}
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#endif
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#endif
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parserInitialized = 0;
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}
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/**
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@ -636,10 +632,10 @@ xmlGetGlobalState(void)
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static int
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xmlIsMainThreadInternal(void) {
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if (parserInitialized == 0) {
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xmlInitParser();
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parserInitialized = 1;
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}
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/*
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* Make sure that mainthread is initialized.
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*/
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xmlInitParser();
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#ifdef HAVE_POSIX_THREADS
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return (pthread_equal(mainthread, pthread_self()));
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206
threads.c
206
threads.c
@ -374,90 +374,52 @@ xmlCleanupThreads(void)
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************************************************************************/
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static int xmlParserInitialized = 0;
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static int xmlParserInnerInitialized = 0;
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#ifdef HAVE_POSIX_THREADS
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static pthread_mutex_t global_init_lock = PTHREAD_MUTEX_INITIALIZER;
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static pthread_once_t onceControl = PTHREAD_ONCE_INIT;
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#elif defined HAVE_WIN32_THREADS
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static volatile LPCRITICAL_SECTION global_init_lock = NULL;
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static INIT_ONCE onceControl = INIT_ONCE_STATIC_INIT;
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#else
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static int onceControl = 0;
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#endif
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/**
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* xmlGlobalInitMutexLock
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*
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* Makes sure that the global initialization mutex is initialized and
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* locks it.
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*/
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static void
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xmlGlobalInitMutexLock(void) {
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#ifdef HAVE_POSIX_THREADS
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/* The mutex is statically initialized, so we just lock it. */
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pthread_mutex_lock(&global_init_lock);
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#elif defined HAVE_WIN32_THREADS
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LPCRITICAL_SECTION cs;
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/* Create a new critical section */
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if (global_init_lock == NULL) {
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cs = malloc(sizeof(CRITICAL_SECTION));
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if (cs == NULL)
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xmlAbort("libxml2: xmlInitParser: out of memory\n");
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InitializeCriticalSection(cs);
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/* Swap it into the global_init_lock */
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#ifdef InterlockedCompareExchangePointer
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InterlockedCompareExchangePointer((void **) &global_init_lock,
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cs, NULL);
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#else /* Use older void* version */
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InterlockedCompareExchange((void **) &global_init_lock,
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(void *) cs, NULL);
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#endif /* InterlockedCompareExchangePointer */
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/* If another thread successfully recorded its critical
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* section in the global_init_lock then discard the one
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* allocated by this thread. */
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if (global_init_lock != cs) {
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DeleteCriticalSection(cs);
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free(cs);
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}
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}
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/* Lock the chosen critical section */
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EnterCriticalSection(global_init_lock);
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#endif
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}
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static void
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xmlGlobalInitMutexUnlock(void) {
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#ifdef HAVE_POSIX_THREADS
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pthread_mutex_unlock(&global_init_lock);
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#elif defined HAVE_WIN32_THREADS
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if (global_init_lock != NULL)
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LeaveCriticalSection(global_init_lock);
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xmlInitParserInternal(void) {
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#if defined(_WIN32) && \
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!defined(LIBXML_THREAD_ALLOC_ENABLED) && \
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(!defined(LIBXML_STATIC) || defined(LIBXML_STATIC_FOR_DLL))
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if (xmlFree == free)
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atexit(xmlCleanupParser);
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#endif
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/*
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* Note that the initialization code must not make memory allocations.
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*/
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xmlInitRandom(); /* Required by xmlInitGlobalsInternal */
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xmlInitMemoryInternal();
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xmlInitGlobalsInternal();
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xmlInitDictInternal();
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xmlInitEncodingInternal();
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#if defined(LIBXML_XPATH_ENABLED)
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xmlInitXPathInternal();
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#endif
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xmlInitIOCallbacks();
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#ifdef LIBXML_CATALOG_ENABLED
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xmlInitCatalogInternal();
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#endif
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xmlParserInitialized = 1;
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}
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/**
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* xmlGlobalInitMutexDestroy
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*
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* Makes sure that the global initialization mutex is destroyed before
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* application termination.
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*/
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static void
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xmlGlobalInitMutexDestroy(void) {
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#ifdef HAVE_POSIX_THREADS
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#elif defined HAVE_WIN32_THREADS
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if (global_init_lock != NULL) {
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DeleteCriticalSection(global_init_lock);
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free(global_init_lock);
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global_init_lock = NULL;
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}
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#endif
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#if defined(HAVE_WIN32_THREADS)
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static BOOL
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xmlInitParserWinWrapper(INIT_ONCE *initOnce ATTRIBUTE_UNUSED,
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void *parameter ATTRIBUTE_UNUSED,
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void **context ATTRIBUTE_UNUSED) {
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xmlInitParserInternal();
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return(TRUE);
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}
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#endif
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/**
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* xmlInitParser:
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@ -469,63 +431,32 @@ xmlGlobalInitMutexDestroy(void) {
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*/
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void
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xmlInitParser(void) {
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/*
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* Note that the initialization code must not make memory allocations.
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*/
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if (xmlParserInitialized != 0)
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return;
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xmlGlobalInitMutexLock();
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if (xmlParserInnerInitialized == 0) {
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#if defined(_WIN32) && \
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!defined(LIBXML_THREAD_ALLOC_ENABLED) && \
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(!defined(LIBXML_STATIC) || defined(LIBXML_STATIC_FOR_DLL))
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if (xmlFree == free)
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atexit(xmlCleanupParser);
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#endif
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xmlInitRandom(); /* Required by xmlInitGlobalsInternal */
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xmlInitMemoryInternal();
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xmlInitGlobalsInternal();
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xmlInitDictInternal();
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xmlInitEncodingInternal();
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#if defined(LIBXML_XPATH_ENABLED)
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xmlInitXPathInternal();
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#endif
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xmlInitIOCallbacks();
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#ifdef LIBXML_CATALOG_ENABLED
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xmlInitCatalogInternal();
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#endif
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xmlParserInnerInitialized = 1;
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#ifdef HAVE_POSIX_THREADS
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pthread_once(&onceControl, xmlInitParserInternal);
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#elif defined(HAVE_WIN32_THREADS)
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InitOnceExecuteOnce(&onceControl, xmlInitParserWinWrapper, NULL, NULL);
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#else
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if (onceControl == 0) {
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xmlInitParserInternal();
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onceControl = 1;
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}
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xmlGlobalInitMutexUnlock();
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xmlParserInitialized = 1;
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#endif
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}
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/**
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* xmlCleanupParser:
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*
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* This function name is somewhat misleading. It does not clean up
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* parser state, it cleans up memory allocated by the library itself.
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* It is a cleanup function for the XML library. It tries to reclaim all
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* related global memory allocated for the library processing.
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* It doesn't deallocate any document related memory. One should
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* call xmlCleanupParser() only when the process has finished using
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* the library and all XML/HTML documents built with it.
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* See also xmlInitParser() which has the opposite function of preparing
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* the library for operations.
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* This function is named somewhat misleadingly. It does not clean up
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* parser state but global memory allocated by the library itself. This
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* function is mainly useful to avoid false positives from memory leak
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* checkers and SHOULD ONLY BE CALLED RIGHT BEFORE THE WHOLE PROCESS
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* EXITS.
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*
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* WARNING: if your application is multithreaded or has plugin support
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* calling this may crash the application if another thread or
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* a plugin is still using libxml2. It's sometimes very hard to
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* guess if libxml2 is in use in the application, some libraries
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* or plugins may use it without notice. In case of doubt abstain
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* from calling this function or do it just before calling exit()
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* to avoid leak reports from valgrind !
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* WARNING: If a process is multithreaded or uses other shared or
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* dynamic libraries, calling this function may cause crashes if
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* another thread or library is still using libxml2. It can be very
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* hard to guess if libxml2 is in use by a process. In case of doubt
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* abstain from calling this function.
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*/
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void
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xmlCleanupParser(void) {
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@ -533,7 +464,6 @@ xmlCleanupParser(void) {
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return;
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/* These functions can call xmlFree. */
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xmlCleanupCharEncodingHandlers();
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#ifdef LIBXML_CATALOG_ENABLED
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xmlCatalogCleanup();
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@ -545,20 +475,34 @@ xmlCleanupParser(void) {
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#endif
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/* These functions should never call xmlFree. */
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xmlCleanupDictInternal();
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xmlCleanupRandom();
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xmlCleanupGlobalsInternal();
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/*
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* Must come last. On Windows, xmlCleanupGlobalsInternal can call
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* xmlFree which uses xmlMemMutex in debug mode.
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* Must come last. xmlCleanupGlobalsInternal can call xmlFree which
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* uses xmlMemMutex in debug mode.
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*/
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xmlCleanupMemoryInternal();
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xmlGlobalInitMutexDestroy();
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xmlParserInitialized = 0;
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xmlParserInnerInitialized = 0;
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/*
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* This is a bit sketchy but should make reinitialization work.
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*/
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#ifdef HAVE_POSIX_THREADS
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{
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pthread_once_t tmp = PTHREAD_ONCE_INIT;
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memcpy(&onceControl, &tmp, sizeof(tmp));
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}
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#elif defined(HAVE_WIN32_THREADS)
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{
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INIT_ONCE tmp = INIT_ONCE_STATIC_INIT;
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memcpy(&onceControl, &tmp, sizeof(tmp));
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}
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#else
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onceControl = 0;
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#endif
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}
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#if defined(HAVE_FUNC_ATTRIBUTE_DESTRUCTOR) && \
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