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[NSS] sqlite3: turn explicitly linked InterlockedCompareExchange to dynamic loading with emulation, should work on Win95, and remove usage of GetFileAttributesExW which is not exist on NT 3.51

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This commit is contained in:
Roy Tam 2020-01-27 12:16:12 +08:00
parent cd62ee1102
commit 9ab743b4d6
1 changed files with 69 additions and 27 deletions
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94
security/nss/lib/sqlite/sqlite3.c
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@ -18318,6 +18318,51 @@ static int winMutexNotheld(sqlite3_mutex *p){
#endif
typedef PVOID WINAPI interlocked_cmp_xchg_t(PVOID *dest, PVOID exc, PVOID comperand);
/* Sorry mate, but we haven't got InterlockedCompareExchange in Win95! */
static PVOID WINAPI
interlocked_cmp_xchg(PVOID *dest, PVOID exc, PVOID comperand)
{
static LONG spinlock = 0;
PVOID result;
DWORD dwSleep = 0;
/* Acqire spinlock (yielding control to other threads if cant aquire for the moment) */
while(InterlockedExchange(&spinlock, 1))
{
// Using Sleep(0) can cause a priority inversion.
// Sleep(0) only yields the processor if there's
// another thread of the same priority that's
// ready to run. If a high-priority thread is
// trying to acquire the lock, which is held by
// a low-priority thread, then the low-priority
// thread may never get scheduled and hence never
// free the lock. NT attempts to avoid priority
// inversions by temporarily boosting the priority
// of low-priority runnable threads, but the problem
// can still occur if there's a medium-priority
// thread that's always runnable. If Sleep(1) is used,
// then the thread unconditionally yields the CPU. We
// only do this for the second and subsequent even
// iterations, since a millisecond is a long time to wait
// if the thread can be scheduled in again sooner
// (~100,000 instructions).
// Avoid priority inversion: 0, 1, 0, 1,...
Sleep(dwSleep);
dwSleep = !dwSleep;
}
result = *dest;
if (result == comperand)
*dest = exc;
/* Release spinlock */
spinlock = 0;
return result;
}
static interlocked_cmp_xchg_t *ixchg;
/*
** Initialize and deinitialize the mutex subsystem.
*/
@ -18340,8 +18385,15 @@ static long winMutex_lock = 0;
SQLITE_API void sqlite3_win32_sleep(DWORD milliseconds); /* os_win.c */
static int winMutexInit(void){
if (!ixchg)
{
/* Sorely, Win95 has no InterlockedCompareExchange API (Win98 has), so we have to use emulation */
HANDLE kernel = GetModuleHandleA("kernel32.dll");
if (!kernel || (ixchg = (interlocked_cmp_xchg_t *)GetProcAddress(kernel, "InterlockedCompareExchange")) == NULL)
ixchg = interlocked_cmp_xchg;
}
/* The first to increment to 1 does actual initialization */
if( InterlockedCompareExchange(&winMutex_lock, 1, 0)==0 ){
if( ixchg(&winMutex_lock, 1, 0)==0 ){
int i;
for(i=0; i<ArraySize(winMutex_staticMutexes); i++){
#if SQLITE_OS_WINRT
@ -18363,7 +18415,7 @@ static int winMutexInit(void){
static int winMutexEnd(void){
/* The first to decrement to 0 does actual shutdown
** (which should be the last to shutdown.) */
if( InterlockedCompareExchange(&winMutex_lock, 0, 1)==1 ){
if( ixchg(&winMutex_lock, 0, 1)==1 ){
if( winMutex_isInit==1 ){
int i;
for(i=0; i<ArraySize(winMutex_staticMutexes); i++){
@ -30594,7 +30646,7 @@ static struct win_syscall {
#define osGetFileAttributesW ((DWORD(WINAPI*)(LPCWSTR))aSyscall[21].pCurrent)
#if defined(SQLITE_WIN32_HAS_WIDE)
#if 0//defined(SQLITE_WIN32_HAS_WIDE)
{ "GetFileAttributesExW", (SYSCALL)GetFileAttributesExW, 0 },
#else
{ "GetFileAttributesExW", (SYSCALL)0, 0 },
@ -33683,16 +33735,7 @@ static int winIsDir(const void *zConverted){
DWORD lastErrno;
if( isNT() ){
int cnt = 0;
WIN32_FILE_ATTRIBUTE_DATA sAttrData;
memset(&sAttrData, 0, sizeof(sAttrData));
while( !(rc = osGetFileAttributesExW((LPCWSTR)zConverted,
GetFileExInfoStandard,
&sAttrData)) && retryIoerr(&cnt, &lastErrno) ){}
if( !rc ){
return 0; /* Invalid name? */
}
attr = sAttrData.dwFileAttributes;
attr = osGetFileAttributesW((WCHAR*)zConverted);
#if SQLITE_OS_WINCE==0
}else{
attr = osGetFileAttributesA((char*)zConverted);
@ -34088,6 +34131,9 @@ static int winAccess(
int rc = 0;
DWORD lastErrno;
void *zConverted;
HANDLE hFile;
DWORD lFilesize;
int cnt = 0;
UNUSED_PARAMETER(pVfs);
SimulateIOError( return SQLITE_IOERR_ACCESS; );
@ -34096,26 +34142,22 @@ static int winAccess(
return SQLITE_IOERR_NOMEM;
}
if( isNT() ){
int cnt = 0;
WIN32_FILE_ATTRIBUTE_DATA sAttrData;
memset(&sAttrData, 0, sizeof(sAttrData));
while( !(rc = osGetFileAttributesExW((LPCWSTR)zConverted,
GetFileExInfoStandard,
&sAttrData)) && retryIoerr(&cnt, &lastErrno) ){}
if( rc ){
if( attr = GetFileAttributesW((WCHAR*)zConverted) ){
/* For an SQLITE_ACCESS_EXISTS query, treat a zero-length file
** as if it does not exist.
*/
if( flags==SQLITE_ACCESS_EXISTS
&& sAttrData.nFileSizeHigh==0
&& sAttrData.nFileSizeLow==0 ){
if( flags==SQLITE_ACCESS_EXISTS && attr != INVALID_FILE_ATTRIBUTES ){
hFile = CreateFileW((WCHAR*)zConverted, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
lFilesize = GetFileSize(hFile,NULL);
if(!lFilesize)
attr = INVALID_FILE_ATTRIBUTES;
}else{
attr = sAttrData.dwFileAttributes;
CloseHandle(hFile);
/*}else{
attr = sAttrData.dwFileAttributes;*/
}
}else{
logIoerr(cnt);
if( lastErrno!=ERROR_FILE_NOT_FOUND && lastErrno!=ERROR_PATH_NOT_FOUND ){
if( lastErrno!=ERROR_FILE_NOT_FOUND ){
winLogError(SQLITE_IOERR_ACCESS, lastErrno, "winAccess", zFilename);
sqlite3_free(zConverted);
return SQLITE_IOERR_ACCESS;