tdesktop/Telegram/SourceFiles/_other/updater.cpp

606 lines
20 KiB
C++

/*
This file is part of Telegram Desktop,
the official desktop application for the Telegram messaging service.
For license and copyright information please follow this link:
https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
*/
#include "updater.h"
bool _debug = false;
wstring updaterName, updaterDir, updateTo, exeName, customWorkingDir, customKeyFile;
bool equal(const wstring &a, const wstring &b) {
return !_wcsicmp(a.c_str(), b.c_str());
}
void updateError(const WCHAR *msg, DWORD errorCode) {
WCHAR errMsg[2048];
LPWSTR errorTextFormatted = nullptr;
auto formatFlags = FORMAT_MESSAGE_FROM_SYSTEM
| FORMAT_MESSAGE_ALLOCATE_BUFFER
| FORMAT_MESSAGE_IGNORE_INSERTS;
FormatMessage(
formatFlags,
NULL,
errorCode,
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
(LPWSTR)&errorTextFormatted,
0,
0);
auto errorText = errorTextFormatted
? errorTextFormatted
: L"(Unknown error)";
wsprintf(errMsg, L"%s, error code: %d\nError message: %s", msg, errorCode, errorText);
MessageBox(0, errMsg, L"Update error!", MB_ICONERROR);
LocalFree(errorTextFormatted);
}
HANDLE _logFile = 0;
void openLog() {
if (!_debug || _logFile) return;
wstring logPath = L"DebugLogs";
if (!CreateDirectory(logPath.c_str(), NULL)) {
DWORD errorCode = GetLastError();
if (errorCode && errorCode != ERROR_ALREADY_EXISTS) {
updateError(L"Failed to create log directory", errorCode);
return;
}
}
SYSTEMTIME stLocalTime;
GetLocalTime(&stLocalTime);
static const int maxFileLen = MAX_PATH * 10;
WCHAR logName[maxFileLen];
wsprintf(logName, L"DebugLogs\\%04d%02d%02d_%02d%02d%02d_upd.txt",
stLocalTime.wYear, stLocalTime.wMonth, stLocalTime.wDay,
stLocalTime.wHour, stLocalTime.wMinute, stLocalTime.wSecond);
_logFile = CreateFile(logName, GENERIC_WRITE, FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, 0, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, 0);
if (_logFile == INVALID_HANDLE_VALUE) { // :(
updateError(L"Failed to create log file", GetLastError());
_logFile = 0;
return;
}
}
void closeLog() {
if (!_logFile) return;
CloseHandle(_logFile);
_logFile = 0;
}
void writeLog(const wstring &msg) {
if (!_logFile) return;
wstring full = msg + L'\n';
DWORD written = 0;
BOOL result = WriteFile(_logFile, full.c_str(), full.size() * sizeof(wchar_t), &written, 0);
if (!result) {
updateError((L"Failed to write log entry '" + msg + L"'").c_str(), GetLastError());
closeLog();
return;
}
BOOL flushr = FlushFileBuffers(_logFile);
if (!flushr) {
updateError((L"Failed to flush log on entry '" + msg + L"'").c_str(), GetLastError());
closeLog();
return;
}
}
void fullClearPath(const wstring &dir) {
WCHAR path[4096];
memcpy(path, dir.c_str(), (dir.size() + 1) * sizeof(WCHAR));
path[dir.size() + 1] = 0;
writeLog(L"Fully clearing path '" + dir + L"'..");
SHFILEOPSTRUCT file_op = {
NULL,
FO_DELETE,
path,
L"",
FOF_NOCONFIRMATION |
FOF_NOERRORUI |
FOF_SILENT,
false,
0,
L""
};
int res = SHFileOperation(&file_op);
if (res) writeLog(L"Error: failed to clear path! :(");
}
void delFolder() {
wstring delPathOld = L"tupdates\\ready", delPath = L"tupdates\\temp", delFolder = L"tupdates";
fullClearPath(delPathOld);
fullClearPath(delPath);
RemoveDirectory(delFolder.c_str());
}
DWORD versionNum = 0, versionLen = 0, readLen = 0;
WCHAR versionStr[32] = { 0 };
bool update() {
writeLog(L"Update started..");
wstring updDir = L"tupdates\\temp", readyFilePath = L"tupdates\\temp\\ready", tdataDir = L"tupdates\\temp\\tdata";
{
HANDLE readyFile = CreateFile(readyFilePath.c_str(), GENERIC_READ, FILE_SHARE_READ, 0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
if (readyFile != INVALID_HANDLE_VALUE) {
CloseHandle(readyFile);
} else {
updDir = L"tupdates\\ready"; // old
tdataDir = L"tupdates\\ready\\tdata";
}
}
HANDLE versionFile = CreateFile((tdataDir + L"\\version").c_str(), GENERIC_READ, FILE_SHARE_READ, 0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
if (versionFile != INVALID_HANDLE_VALUE) {
if (!ReadFile(versionFile, &versionNum, sizeof(DWORD), &readLen, NULL) || readLen != sizeof(DWORD)) {
versionNum = 0;
} else {
if (versionNum == 0x7FFFFFFF) { // alpha version
} else if (!ReadFile(versionFile, &versionLen, sizeof(DWORD), &readLen, NULL) || readLen != sizeof(DWORD) || versionLen > 63) {
versionNum = 0;
} else if (!ReadFile(versionFile, versionStr, versionLen, &readLen, NULL) || readLen != versionLen) {
versionNum = 0;
}
}
CloseHandle(versionFile);
writeLog(L"Version file read.");
} else {
writeLog(L"Could not open version file to update registry :(");
}
deque<wstring> dirs;
dirs.push_back(updDir);
deque<wstring> from, to, forcedirs;
do {
wstring dir = dirs.front();
dirs.pop_front();
wstring toDir = updateTo;
if (dir.size() > updDir.size() + 1) {
toDir += (dir.substr(updDir.size() + 1) + L"\\");
forcedirs.push_back(toDir);
writeLog(L"Parsing dir '" + toDir + L"' in update tree..");
}
WIN32_FIND_DATA findData;
HANDLE findHandle = FindFirstFileEx((dir + L"\\*").c_str(), FindExInfoStandard, &findData, FindExSearchNameMatch, 0, 0);
if (findHandle == INVALID_HANDLE_VALUE) {
DWORD errorCode = GetLastError();
if (errorCode == ERROR_PATH_NOT_FOUND) { // no update is ready
return true;
}
writeLog(L"Error: failed to find update files :(");
updateError(L"Failed to find update files", errorCode);
delFolder();
return false;
}
do {
wstring fname = dir + L"\\" + findData.cFileName;
if (fname.substr(0, tdataDir.size()) == tdataDir && (fname.size() <= tdataDir.size() || fname.at(tdataDir.size()) == '/')) {
writeLog(L"Skipped 'tdata' path '" + fname + L"'");
} else if (findData.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
if (findData.cFileName != wstring(L".") && findData.cFileName != wstring(L"..")) {
dirs.push_back(fname);
writeLog(L"Added dir '" + fname + L"' in update tree..");
}
} else {
wstring tofname = updateTo + fname.substr(updDir.size() + 1);
if (equal(tofname, updaterName)) { // bad update - has Updater.exe - delete all dir
writeLog(L"Error: bad update, has Updater.exe! '" + tofname + L"' equal '" + updaterName + L"'");
delFolder();
return false;
} else if (equal(tofname, updateTo + L"Telegram.exe") && exeName != L"Telegram.exe") {
wstring fullBinaryPath = updateTo + exeName;
writeLog(L"Target binary found: '" + tofname + L"', changing to '" + fullBinaryPath + L"'");
tofname = fullBinaryPath;
}
if (equal(fname, readyFilePath)) {
writeLog(L"Skipped ready file '" + fname + L"'");
} else {
from.push_back(fname);
to.push_back(tofname);
writeLog(L"Added file '" + fname + L"' to be copied to '" + tofname + L"'");
}
}
} while (FindNextFile(findHandle, &findData));
DWORD errorCode = GetLastError();
if (errorCode && errorCode != ERROR_NO_MORE_FILES) { // everything is found
writeLog(L"Error: failed to find next update file :(");
updateError(L"Failed to find next update file", errorCode);
delFolder();
return false;
}
FindClose(findHandle);
} while (!dirs.empty());
for (size_t i = 0; i < forcedirs.size(); ++i) {
wstring forcedir = forcedirs[i];
writeLog(L"Forcing dir '" + forcedir + L"'..");
if (!forcedir.empty() && !CreateDirectory(forcedir.c_str(), NULL)) {
DWORD errorCode = GetLastError();
if (errorCode && errorCode != ERROR_ALREADY_EXISTS) {
writeLog(L"Error: failed to create dir '" + forcedir + L"'..");
updateError(L"Failed to create directory", errorCode);
delFolder();
return false;
}
writeLog(L"Already exists!");
}
}
for (size_t i = 0; i < from.size(); ++i) {
wstring fname = from[i], tofname = to[i];
BOOL copyResult;
do {
writeLog(L"Copying file '" + fname + L"' to '" + tofname + L"'..");
int copyTries = 0;
do {
copyResult = CopyFile(fname.c_str(), tofname.c_str(), FALSE);
if (!copyResult) {
++copyTries;
Sleep(100);
} else {
break;
}
} while (copyTries < 100);
if (!copyResult) {
writeLog(L"Error: failed to copy, asking to retry..");
WCHAR errMsg[2048];
wsprintf(errMsg, L"Failed to update Telegram :(\n%s is not accessible.", tofname.c_str());
if (MessageBox(0, errMsg, L"Update error!", MB_ICONERROR | MB_RETRYCANCEL) != IDRETRY) {
delFolder();
return false;
}
}
} while (!copyResult);
}
writeLog(L"Update succeed! Clearing folder..");
delFolder();
return true;
}
void updateRegistry() {
if (versionNum && versionNum != 0x7FFFFFFF) {
writeLog(L"Updating registry..");
versionStr[versionLen / 2] = 0;
HKEY rkey;
LSTATUS status = RegOpenKeyEx(HKEY_CURRENT_USER, L"Software\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\{53F49750-6209-4FBF-9CA8-7A333C87D1ED}_is1", 0, KEY_QUERY_VALUE | KEY_SET_VALUE, &rkey);
if (status == ERROR_SUCCESS) {
writeLog(L"Checking registry install location..");
static const int bufSize = 4096;
DWORD locationType, locationSize = bufSize * 2;
WCHAR locationStr[bufSize], exp[bufSize];
if (RegQueryValueEx(rkey, L"InstallLocation", 0, &locationType, (BYTE*)locationStr, &locationSize) == ERROR_SUCCESS) {
locationSize /= 2;
if (locationStr[locationSize - 1]) {
locationStr[locationSize++] = 0;
}
if (locationType == REG_EXPAND_SZ) {
DWORD copy = ExpandEnvironmentStrings(locationStr, exp, bufSize);
if (copy <= bufSize) {
memcpy(locationStr, exp, copy * sizeof(WCHAR));
}
}
if (locationType == REG_EXPAND_SZ || locationType == REG_SZ) {
if (PathCanonicalize(exp, locationStr)) {
memcpy(locationStr, exp, bufSize * sizeof(WCHAR));
if (GetFullPathName(L".", bufSize, exp, 0) < bufSize) {
wstring installpath = locationStr, mypath = exp;
if (installpath == mypath + L"\\" || true) { // always update reg info, if we found it
WCHAR nameStr[bufSize], dateStr[bufSize], publisherStr[bufSize], icongroupStr[bufSize];
SYSTEMTIME stLocalTime;
GetLocalTime(&stLocalTime);
RegSetValueEx(rkey, L"DisplayVersion", 0, REG_SZ, (const BYTE*)versionStr, ((versionLen / 2) + 1) * sizeof(WCHAR));
wsprintf(nameStr, L"Telegram Desktop version %s", versionStr);
RegSetValueEx(rkey, L"DisplayName", 0, REG_SZ, (const BYTE*)nameStr, (wcslen(nameStr) + 1) * sizeof(WCHAR));
wsprintf(publisherStr, L"Telegram Messenger LLP");
RegSetValueEx(rkey, L"Publisher", 0, REG_SZ, (const BYTE*)publisherStr, (wcslen(publisherStr) + 1) * sizeof(WCHAR));
wsprintf(icongroupStr, L"Telegram Desktop");
RegSetValueEx(rkey, L"Inno Setup: Icon Group", 0, REG_SZ, (const BYTE*)icongroupStr, (wcslen(icongroupStr) + 1) * sizeof(WCHAR));
wsprintf(dateStr, L"%04d%02d%02d", stLocalTime.wYear, stLocalTime.wMonth, stLocalTime.wDay);
RegSetValueEx(rkey, L"InstallDate", 0, REG_SZ, (const BYTE*)dateStr, (wcslen(dateStr) + 1) * sizeof(WCHAR));
const WCHAR *appURL = L"https://desktop.telegram.org";
RegSetValueEx(rkey, L"HelpLink", 0, REG_SZ, (const BYTE*)appURL, (wcslen(appURL) + 1) * sizeof(WCHAR));
RegSetValueEx(rkey, L"URLInfoAbout", 0, REG_SZ, (const BYTE*)appURL, (wcslen(appURL) + 1) * sizeof(WCHAR));
RegSetValueEx(rkey, L"URLUpdateInfo", 0, REG_SZ, (const BYTE*)appURL, (wcslen(appURL) + 1) * sizeof(WCHAR));
}
}
}
}
}
RegCloseKey(rkey);
}
}
}
int APIENTRY wWinMain(HINSTANCE instance, HINSTANCE prevInstance, LPWSTR cmdParamarg, int cmdShow) {
openLog();
_oldWndExceptionFilter = SetUnhandledExceptionFilter(_exceptionFilter);
// CAPIHook apiHook("kernel32.dll", "SetUnhandledExceptionFilter", (PROC)RedirectedSetUnhandledExceptionFilter);
writeLog(L"Updaters started..");
LPWSTR *args;
int argsCount;
bool needupdate = false, autostart = false, debug = false, writeprotected = false, startintray = false, testmode = false, externalupdater = false;
args = CommandLineToArgvW(GetCommandLine(), &argsCount);
if (args) {
for (int i = 1; i < argsCount; ++i) {
writeLog(std::wstring(L"Argument: ") + args[i]);
if (equal(args[i], L"-update")) {
needupdate = true;
} else if (equal(args[i], L"-autostart")) {
autostart = true;
} else if (equal(args[i], L"-debug")) {
debug = _debug = true;
openLog();
} else if (equal(args[i], L"-startintray")) {
startintray = true;
} else if (equal(args[i], L"-testmode")) {
testmode = true;
} else if (equal(args[i], L"-externalupdater")) {
externalupdater = true;
} else if (equal(args[i], L"-writeprotected") && ++i < argsCount) {
writeLog(std::wstring(L"Argument: ") + args[i]);
writeprotected = true;
updateTo = args[i];
for (int j = 0, l = updateTo.size(); j < l; ++j) {
if (updateTo[j] == L'/') {
updateTo[j] = L'\\';
}
}
} else if (equal(args[i], L"-workdir") && ++i < argsCount) {
writeLog(std::wstring(L"Argument: ") + args[i]);
customWorkingDir = args[i];
} else if (equal(args[i], L"-key") && ++i < argsCount) {
writeLog(std::wstring(L"Argument: ") + args[i]);
customKeyFile = args[i];
} else if (equal(args[i], L"-exename") && ++i < argsCount) {
writeLog(std::wstring(L"Argument: ") + args[i]);
exeName = args[i];
for (int j = 0, l = exeName.size(); j < l; ++j) {
if (exeName[j] == L'/' || exeName[j] == L'\\') {
exeName = L"Telegram.exe";
break;
}
}
}
}
if (exeName.empty()) {
exeName = L"Telegram.exe";
}
if (needupdate) writeLog(L"Need to update!");
if (autostart) writeLog(L"From autostart!");
if (writeprotected) writeLog(L"Write Protected folder!");
if (!customWorkingDir.empty()) writeLog(L"Will pass custom working dir: " + customWorkingDir);
updaterName = args[0];
writeLog(L"Updater name is: " + updaterName);
if (updaterName.size() > 11) {
if (equal(updaterName.substr(updaterName.size() - 11), L"Updater.exe")) {
updaterDir = updaterName.substr(0, updaterName.size() - 11);
writeLog(L"Updater dir is: " + updaterDir);
if (!writeprotected) {
updateTo = updaterDir;
}
writeLog(L"Update to: " + updateTo);
if (needupdate && update()) {
updateRegistry();
}
if (writeprotected) { // if we can't clear all tupdates\ready (Updater.exe is there) - clear only version
if (DeleteFile(L"tupdates\\temp\\tdata\\version") || DeleteFile(L"tupdates\\ready\\tdata\\version")) {
writeLog(L"Version file deleted!");
} else {
writeLog(L"Error: could not delete version file");
}
}
} else {
writeLog(L"Error: bad exe name!");
}
} else {
writeLog(L"Error: short exe name!");
}
LocalFree(args);
} else {
writeLog(L"Error: No command line arguments!");
}
wstring targs;
if (autostart) targs += L" -autostart";
if (debug) targs += L" -debug";
if (startintray) targs += L" -startintray";
if (testmode) targs += L" -testmode";
if (externalupdater) targs += L" -externalupdater";
if (!customWorkingDir.empty()) {
targs += L" -workdir \"" + customWorkingDir + L"\"";
}
if (!customKeyFile.empty()) {
targs += L" -key \"" + customKeyFile + L"\"";
}
writeLog(L"Result arguments: " + targs);
bool executed = false;
if (writeprotected) { // run un-elevated
writeLog(L"Trying to run un-elevated by temp.lnk");
HRESULT hres = CoInitialize(0);
if (SUCCEEDED(hres)) {
IShellLink* psl;
HRESULT hres = CoCreateInstance(CLSID_ShellLink, NULL, CLSCTX_INPROC_SERVER, IID_IShellLink, (LPVOID*)&psl);
if (SUCCEEDED(hres)) {
IPersistFile* ppf;
wstring exe = updateTo + exeName, dir = updateTo;
psl->SetArguments((targs.size() ? targs.substr(1) : targs).c_str());
psl->SetPath(exe.c_str());
psl->SetWorkingDirectory(dir.c_str());
psl->SetDescription(L"");
hres = psl->QueryInterface(IID_IPersistFile, (LPVOID*)&ppf);
if (SUCCEEDED(hres)) {
wstring lnk = L"tupdates\\temp\\temp.lnk";
hres = ppf->Save(lnk.c_str(), TRUE);
if (!SUCCEEDED(hres)) {
lnk = L"tupdates\\ready\\temp.lnk"; // old
hres = ppf->Save(lnk.c_str(), TRUE);
}
ppf->Release();
if (SUCCEEDED(hres)) {
writeLog(L"Executing un-elevated through link..");
ShellExecute(0, 0, L"explorer.exe", lnk.c_str(), 0, SW_SHOWNORMAL);
executed = true;
} else {
writeLog(L"Error: ppf->Save failed");
}
} else {
writeLog(L"Error: Could not create interface IID_IPersistFile");
}
psl->Release();
} else {
writeLog(L"Error: could not create instance of IID_IShellLink");
}
CoUninitialize();
} else {
writeLog(L"Error: Could not initialize COM");
}
}
if (!executed) {
ShellExecute(0, 0, (updateTo + exeName).c_str(), (L"-noupdate" + targs).c_str(), 0, SW_SHOWNORMAL);
}
writeLog(L"Executed '" + exeName + L"', closing log and quitting..");
closeLog();
return 0;
}
static const WCHAR *_programName = L"Telegram Desktop"; // folder in APPDATA, if current path is unavailable for writing
static const WCHAR *_exeName = L"Updater.exe";
LPTOP_LEVEL_EXCEPTION_FILTER _oldWndExceptionFilter = 0;
typedef BOOL (FAR STDAPICALLTYPE *t_miniDumpWriteDump)(
_In_ HANDLE hProcess,
_In_ DWORD ProcessId,
_In_ HANDLE hFile,
_In_ MINIDUMP_TYPE DumpType,
_In_opt_ PMINIDUMP_EXCEPTION_INFORMATION ExceptionParam,
_In_opt_ PMINIDUMP_USER_STREAM_INFORMATION UserStreamParam,
_In_opt_ PMINIDUMP_CALLBACK_INFORMATION CallbackParam
);
t_miniDumpWriteDump miniDumpWriteDump = 0;
HANDLE _generateDumpFileAtPath(const WCHAR *path) {
static const int maxFileLen = MAX_PATH * 10;
WCHAR szPath[maxFileLen];
wsprintf(szPath, L"%stdata\\", path);
if (!CreateDirectory(szPath, NULL)) {
if (GetLastError() != ERROR_ALREADY_EXISTS) {
return 0;
}
}
wsprintf(szPath, L"%sdumps\\", path);
if (!CreateDirectory(szPath, NULL)) {
if (GetLastError() != ERROR_ALREADY_EXISTS) {
return 0;
}
}
WCHAR szFileName[maxFileLen];
WCHAR szExeName[maxFileLen];
wcscpy_s(szExeName, _exeName);
WCHAR *dotFrom = wcschr(szExeName, WCHAR(L'.'));
if (dotFrom) {
wsprintf(dotFrom, L"");
}
SYSTEMTIME stLocalTime;
GetLocalTime(&stLocalTime);
wsprintf(szFileName, L"%s%s-%s-%04d%02d%02d-%02d%02d%02d-%ld-%ld.dmp",
szPath, szExeName, updaterVersionStr,
stLocalTime.wYear, stLocalTime.wMonth, stLocalTime.wDay,
stLocalTime.wHour, stLocalTime.wMinute, stLocalTime.wSecond,
GetCurrentProcessId(), GetCurrentThreadId());
return CreateFile(szFileName, GENERIC_READ|GENERIC_WRITE, FILE_SHARE_WRITE|FILE_SHARE_READ, 0, CREATE_ALWAYS, 0, 0);
}
void _generateDump(EXCEPTION_POINTERS* pExceptionPointers) {
static const int maxFileLen = MAX_PATH * 10;
closeLog();
HMODULE hDll = LoadLibrary(L"DBGHELP.DLL");
if (!hDll) return;
miniDumpWriteDump = (t_miniDumpWriteDump)GetProcAddress(hDll, "MiniDumpWriteDump");
if (!miniDumpWriteDump) return;
HANDLE hDumpFile = 0;
WCHAR szPath[maxFileLen];
DWORD len = GetModuleFileName(GetModuleHandle(0), szPath, maxFileLen);
if (!len) return;
WCHAR *pathEnd = szPath + len;
if (!_wcsicmp(pathEnd - wcslen(_exeName), _exeName)) {
wsprintf(pathEnd - wcslen(_exeName), L"");
hDumpFile = _generateDumpFileAtPath(szPath);
}
if (!hDumpFile || hDumpFile == INVALID_HANDLE_VALUE) {
WCHAR wstrPath[maxFileLen];
DWORD wstrPathLen;
if (wstrPathLen = GetEnvironmentVariable(L"APPDATA", wstrPath, maxFileLen)) {
wsprintf(wstrPath + wstrPathLen, L"\\%s\\", _programName);
hDumpFile = _generateDumpFileAtPath(wstrPath);
}
}
if (!hDumpFile || hDumpFile == INVALID_HANDLE_VALUE) {
return;
}
MINIDUMP_EXCEPTION_INFORMATION ExpParam = {0};
ExpParam.ThreadId = GetCurrentThreadId();
ExpParam.ExceptionPointers = pExceptionPointers;
ExpParam.ClientPointers = TRUE;
miniDumpWriteDump(GetCurrentProcess(), GetCurrentProcessId(), hDumpFile, MiniDumpWithDataSegs, &ExpParam, NULL, NULL);
}
LONG CALLBACK _exceptionFilter(EXCEPTION_POINTERS* pExceptionPointers) {
_generateDump(pExceptionPointers);
return _oldWndExceptionFilter ? (*_oldWndExceptionFilter)(pExceptionPointers) : EXCEPTION_CONTINUE_SEARCH;
}
// see http://www.codeproject.com/Articles/154686/SetUnhandledExceptionFilter-and-the-C-C-Runtime-Li
LPTOP_LEVEL_EXCEPTION_FILTER WINAPI RedirectedSetUnhandledExceptionFilter(_In_opt_ LPTOP_LEVEL_EXCEPTION_FILTER lpTopLevelExceptionFilter) {
// When the CRT calls SetUnhandledExceptionFilter with NULL parameter
// our handler will not get removed.
_oldWndExceptionFilter = lpTopLevelExceptionFilter;
return 0;
}