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globals: Rework global state destruction on Windows

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If DllMain is used, rely on it working as expected. The old code seemed
to attempt to free global state of other threads if, for some reason,
the DllMain mechanism didn't work.

In a static build, register a destructor with
RegisterWaitForSingleObject.

Make public functions xmlGetGlobalState and xmlInitializeGlobalState
no-ops.

Move initialization and registration of global state objects to
xmlInitGlobalState. Lookup global state with xmlGetThreadLocalStorage
which can be inlined nicely.

Also cleanup global state when using TLS. xmlLastError must be reset.
This commit is contained in:
Nick Wellnhofer 2023-09-18 13:25:06 +02:00
parent 39a275a541
commit e7b6ca156f
3 changed files with 131 additions and 191 deletions
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317
globals.c
View File

@ -43,16 +43,17 @@ static xmlMutex xmlThrDefMutex;
type gs_##name;
struct _xmlGlobalState {
#if defined(HAVE_WIN32_THREADS) && \
defined(LIBXML_STATIC) && !defined(LIBXML_STATIC_FOR_DLL)
void *threadHandle;
void *waitHandle;
#endif
#define XML_OP XML_DECLARE_MEMBER
XML_GLOBALS
#undef XML_OP
};
#ifdef LIBXML_THREAD_ENABLED
static void
xmlFreeGlobalState(void *state);
#endif
#ifdef HAVE_POSIX_THREADS
/*
@ -81,42 +82,15 @@ static __declspec(thread) int tlstate_inited = 0;
static DWORD globalkey = TLS_OUT_OF_INDEXES;
#if defined(LIBXML_STATIC) && !defined(LIBXML_STATIC_FOR_DLL)
typedef struct _xmlGlobalStateCleanupHelperParams {
HANDLE thread;
void *memory;
} xmlGlobalStateCleanupHelperParams;
static void
xmlGlobalStateCleanupHelper(void *p)
{
xmlGlobalStateCleanupHelperParams *params =
(xmlGlobalStateCleanupHelperParams *) p;
WaitForSingleObject(params->thread, INFINITE);
CloseHandle(params->thread);
xmlFreeGlobalState(params->memory);
free(params);
_endthread();
}
#else /* LIBXML_STATIC && !LIBXML_STATIC_FOR_DLL */
typedef struct _xmlGlobalStateCleanupHelperParams {
void *memory;
struct _xmlGlobalStateCleanupHelperParams *prev;
struct _xmlGlobalStateCleanupHelperParams *next;
} xmlGlobalStateCleanupHelperParams;
static xmlGlobalStateCleanupHelperParams *cleanup_helpers_head = NULL;
static CRITICAL_SECTION cleanup_helpers_cs;
#endif /* LIBXMLSTATIC && !LIBXML_STATIC_FOR_DLL */
#endif /* HAVE_COMPILER_TLS */
#endif /* HAVE_WIN32_THREADS */
#ifdef LIBXML_THREAD_ENABLED
static void
xmlFreeGlobalState(void *state);
#endif
/************************************************************************
* *
* All the user accessible global variables of the library *
@ -549,9 +523,6 @@ void xmlInitGlobalsInternal(void) {
pthread_key_create(&globalkey, xmlFreeGlobalState);
#elif defined(HAVE_WIN32_THREADS)
#if !defined(HAVE_COMPILER_TLS)
#if !defined(LIBXML_STATIC) || defined(LIBXML_STATIC_FOR_DLL)
InitializeCriticalSection(&cleanup_helpers_cs);
#endif
globalkey = TlsAlloc();
#endif
#endif
@ -587,27 +558,9 @@ void xmlCleanupGlobalsInternal(void) {
#elif defined(HAVE_WIN32_THREADS)
#if !defined(HAVE_COMPILER_TLS)
if (globalkey != TLS_OUT_OF_INDEXES) {
#if !defined(LIBXML_STATIC) || defined(LIBXML_STATIC_FOR_DLL)
xmlGlobalStateCleanupHelperParams *p;
EnterCriticalSection(&cleanup_helpers_cs);
p = cleanup_helpers_head;
while (p != NULL) {
xmlGlobalStateCleanupHelperParams *temp = p;
p = p->next;
xmlFreeGlobalState(temp->memory);
free(temp);
}
cleanup_helpers_head = 0;
LeaveCriticalSection(&cleanup_helpers_cs);
#endif
TlsFree(globalkey);
globalkey = TLS_OUT_OF_INDEXES;
}
#if !defined(LIBXML_STATIC) || defined(LIBXML_STATIC_FOR_DLL)
DeleteCriticalSection(&cleanup_helpers_cs);
#endif
#endif
#endif
}
@ -616,14 +569,80 @@ void xmlCleanupGlobalsInternal(void) {
* xmlInitializeGlobalState:
* @gs: a pointer to a newly allocated global state
*
* DEPRECATED: Internal function, do not use.
*
* xmlInitializeGlobalState() initialize a global state with all the
* default values of the library.
* DEPRECATED: No-op.
*/
void
xmlInitializeGlobalState(xmlGlobalStatePtr gs)
xmlInitializeGlobalState(xmlGlobalStatePtr gs ATTRIBUTE_UNUSED)
{
}
/**
* xmlGetGlobalState:
*
* DEPRECATED: Always returns NULL.
*/
xmlGlobalStatePtr
xmlGetGlobalState(void)
{
return(NULL);
}
#ifdef LIBXML_THREAD_ENABLED
/**
* xmlFreeGlobalState:
* @state: a thread global state
*
* xmlFreeGlobalState() is called when a thread terminates with a non-NULL
* global state. It is is used here to reclaim memory resources.
*/
static void
xmlFreeGlobalState(void *state)
{
xmlGlobalState *gs = (xmlGlobalState *) state;
/* free any memory allocated in the thread's xmlLastError */
xmlResetError(&(gs->gs_xmlLastError));
#if !defined(HAVE_WIN32_THREADS) || !defined(HAVE_COMPILER_TLS)
free(state);
#endif
}
#if defined(HAVE_WIN32_THREADS) && \
defined(LIBXML_STATIC) && !defined(LIBXML_STATIC_FOR_DLL)
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 /* LIBXML_STATIC */
static void
xmlInitGlobalState(xmlGlobalStatePtr gs) {
xmlMutexLock(&xmlThrDefMutex);
#if defined(LIBXML_HTML_ENABLED) && defined(LIBXML_LEGACY_ENABLED) && defined(LIBXML_SAX1_ENABLED)
@ -676,24 +695,17 @@ xmlInitializeGlobalState(xmlGlobalStatePtr gs)
memset(&gs->gs_xmlLastError, 0, sizeof(xmlError));
xmlMutexUnlock(&xmlThrDefMutex);
}
#ifdef LIBXML_THREAD_ENABLED
/**
* xmlFreeGlobalState:
* @state: a thread global state
*
* xmlFreeGlobalState() is called when a thread terminates with a non-NULL
* global state. It is is used here to reclaim memory resources.
*/
static void
xmlFreeGlobalState(void *state)
{
xmlGlobalState *gs = (xmlGlobalState *) state;
/* free any memory allocated in the thread's xmlLastError */
xmlResetError(&(gs->gs_xmlLastError));
free(state);
#ifdef HAVE_POSIX_THREADS
pthread_setspecific(globalkey, gs);
#elif defined HAVE_WIN32_THREADS
#ifndef HAVE_COMPILER_TLS
TlsSetValue(globalkey, gs);
#endif
#if defined(LIBXML_STATIC) && !defined(LIBXML_STATIC_FOR_DLL)
xmlRegisterGlobalStateDtor(gs);
#endif
#endif
}
/**
@ -711,16 +723,40 @@ xmlNewGlobalState(void)
xmlGlobalState *gs;
gs = malloc(sizeof(xmlGlobalState));
if (gs == NULL) {
xmlGenericError(xmlGenericErrorContext,
"xmlGetGlobalState: out of memory\n");
if (gs == NULL)
return (NULL);
}
memset(gs, 0, sizeof(xmlGlobalState));
xmlInitializeGlobalState(gs);
xmlInitGlobalState(gs);
return (gs);
}
static xmlGlobalStatePtr
xmlGetThreadLocalStorage(void) {
#ifdef HAVE_POSIX_THREADS
xmlGlobalState *gs;
gs = (xmlGlobalState *) pthread_getspecific(globalkey);
if (gs == NULL)
gs = xmlNewGlobalState();
return (gs);
#elif defined HAVE_WIN32_THREADS
#if defined(HAVE_COMPILER_TLS)
if (!tlstate_inited) {
tlstate_inited = 1;
xmlInitGlobalState(&tlstate);
}
return &tlstate;
#else /* HAVE_COMPILER_TLS */
xmlGlobalState *gs;
gs = (xmlGlobalState *) TlsGetValue(globalkey);
if (gs == NULL)
gs = xmlNewGlobalState();
return (gs);
#endif /* HAVE_COMPILER_TLS */
#else
return (NULL);
#endif
}
#endif /* LIBXML_THREAD_ENABLED */
/**
@ -743,91 +779,11 @@ xmlNewGlobalState(void)
*/
int
xmlCheckThreadLocalStorage(void) {
if (IS_MAIN_THREAD)
return(0);
return((xmlGetGlobalState() == NULL) ? -1 : 0);
}
/**
* xmlGetGlobalState:
*
* DEPRECATED: Internal function, do not use.
*
* xmlGetGlobalState() is called to retrieve the global state for a thread.
*
* Returns the thread global state or NULL in case of error
*/
xmlGlobalStatePtr
xmlGetGlobalState(void)
{
#ifdef HAVE_POSIX_THREADS
xmlGlobalState *globalval;
if ((globalval = (xmlGlobalState *)
pthread_getspecific(globalkey)) == NULL) {
xmlGlobalState *tsd = xmlNewGlobalState();
if (tsd == NULL)
return(NULL);
pthread_setspecific(globalkey, tsd);
return (tsd);
}
return (globalval);
#elif defined HAVE_WIN32_THREADS
#if defined(HAVE_COMPILER_TLS)
if (!tlstate_inited) {
tlstate_inited = 1;
xmlInitializeGlobalState(&tlstate);
}
return &tlstate;
#else /* HAVE_COMPILER_TLS */
xmlGlobalState *globalval;
xmlGlobalStateCleanupHelperParams *p;
#if defined(LIBXML_STATIC) && !defined(LIBXML_STATIC_FOR_DLL)
globalval = (xmlGlobalState *) TlsGetValue(globalkey);
#else
p = (xmlGlobalStateCleanupHelperParams *) TlsGetValue(globalkey);
globalval = (xmlGlobalState *) (p ? p->memory : NULL);
#endif
if (globalval == NULL) {
xmlGlobalState *tsd = xmlNewGlobalState();
if (tsd == NULL)
return(NULL);
p = (xmlGlobalStateCleanupHelperParams *)
malloc(sizeof(xmlGlobalStateCleanupHelperParams));
if (p == NULL) {
xmlGenericError(xmlGenericErrorContext,
"xmlGetGlobalState: out of memory\n");
xmlFreeGlobalState(tsd);
return(NULL);
}
p->memory = tsd;
#if defined(LIBXML_STATIC) && !defined(LIBXML_STATIC_FOR_DLL)
DuplicateHandle(GetCurrentProcess(), GetCurrentThread(),
GetCurrentProcess(), &p->thread, 0, TRUE,
DUPLICATE_SAME_ACCESS);
TlsSetValue(globalkey, tsd);
_beginthread(xmlGlobalStateCleanupHelper, 0, p);
#else
EnterCriticalSection(&cleanup_helpers_cs);
if (cleanup_helpers_head != NULL) {
cleanup_helpers_head->prev = p;
}
p->next = cleanup_helpers_head;
p->prev = NULL;
cleanup_helpers_head = p;
TlsSetValue(globalkey, p);
LeaveCriticalSection(&cleanup_helpers_cs);
#endif
return (tsd);
}
return (globalval);
#endif /* HAVE_COMPILER_TLS */
#else
return (NULL);
#ifdef LIBXML_THREAD_ENABLED
if ((!xmlIsMainThread()) && (xmlGetThreadLocalStorage() == NULL))
return(-1);
#endif
return(0);
}
/**
@ -842,7 +798,7 @@ xmlGetGlobalState(void)
* Returns TRUE always
*/
#ifdef HAVE_POSIX_THREADS
#elif defined(HAVE_WIN32_THREADS) && !defined(HAVE_COMPILER_TLS) && (!defined(LIBXML_STATIC) || defined(LIBXML_STATIC_FOR_DLL))
#elif defined(HAVE_WIN32_THREADS) && (!defined(LIBXML_STATIC) || defined(LIBXML_STATIC_FOR_DLL))
#if defined(LIBXML_STATIC_FOR_DLL)
int
xmlDllMain(ATTRIBUTE_UNUSED void *hinstDLL, unsigned long fdwReason,
@ -866,26 +822,13 @@ DllMain(ATTRIBUTE_UNUSED HINSTANCE hinstDLL, DWORD fdwReason,
switch (fdwReason) {
case DLL_THREAD_DETACH:
if (globalkey != TLS_OUT_OF_INDEXES) {
xmlGlobalState *globalval = NULL;
xmlGlobalStateCleanupHelperParams *p =
(xmlGlobalStateCleanupHelperParams *)
TlsGetValue(globalkey);
globalval = (xmlGlobalState *) (p ? p->memory : NULL);
xmlGlobalState *globalval;
globalval = (xmlGlobalState *) TlsGetValue(globalkey);
if (globalval) {
xmlFreeGlobalState(globalval);
TlsSetValue(globalkey, NULL);
}
if (p) {
EnterCriticalSection(&cleanup_helpers_cs);
if (p == cleanup_helpers_head)
cleanup_helpers_head = p->next;
else
p->prev->next = p->next;
if (p->next != NULL)
p->next->prev = p->prev;
LeaveCriticalSection(&cleanup_helpers_cs);
free(p);
}
}
break;
}
@ -1138,7 +1081,7 @@ xmlThrDefOutputBufferCreateFilenameDefault(xmlOutputBufferCreateFilenameFunc fun
if (IS_MAIN_THREAD) \
return (&name); \
else \
return (&xmlGetGlobalState()->gs_##name); \
return (&xmlGetThreadLocalStorage()->gs_##name); \
}
#define XML_OP XML_DEFINE_GLOBAL_WRAPPER

2
include/libxml/globals.h
View File

@ -122,7 +122,7 @@ XMLPUBFUN xmlParserInputBufferCreateFilenameFunc
/** DOC_DISABLE */
#if defined(LIBXML_THREAD_ENABLED) && defined(_WIN32) && \
!defined(HAVE_COMPILER_TLS) && defined(LIBXML_STATIC_FOR_DLL)
defined(LIBXML_STATIC_FOR_DLL)
int
xmlDllMain(void *hinstDLL, unsigned long fdwReason,
void *lpvReserved);

3
include/private/threads.h
View File

@ -10,9 +10,6 @@
#elif defined(_WIN32)
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#ifndef HAVE_COMPILER_TLS
#include <process.h>
#endif
#define HAVE_WIN32_THREADS
#endif
#endif