Why is a wchar_t* variable being clobbered? - c++

I'm working with the following piece of code. DLLName is of type wchar_t*, and it's being set early on in my program. Before i reach this point in my code, DLLName is a valid path to a DLL, like L"C:\\Windows\\System32\\advapi32.dll"
wprintf(L"Location: %s\n", DLLName);
HMODULE hDLL = LoadLibraryW(DLLName);
What happens when my code reaches wprintf? The value of DLLName is not printed. In fact, DLLName is now a blank string, L""! Which causes the call to LoadLibraryW() to fail.
Weird. I comment out wprintf. When the debugger reaches the LoadLibraryW(), DLLName is the correct wide string with the path to my DLL. After LoadLibraryW(), the value of DLLName is L"\x4", and the call failed.
What's going on here? I am clueless on how to debug this.
EDIT: All of my code
BOOL FindOriginalCOMServer(wchar_t* GUID, wchar_t** DLLName)
{
HKEY hKey;
HKEY hCLSIDKey;
wchar_t name[MAX_PATH];
DWORD nameLength = MAX_PATH;
wprintf(L"[*] Beginning search for GUID %s\n", GUID);
LONG lResult = RegOpenKeyExW(HKEY_LOCAL_MACHINE, (LPCWSTR)L"SOFTWARE\\Classes\\CLSID", 0, KEY_READ, &hKey);
if (lResult != ERROR_SUCCESS) {
wprintf(L"[-] Error getting CLSID path\n");
return FALSE;
}
// Make sure HKLM\Software\Classes\CLSID\{GUID} exists
lResult = RegOpenKeyExW(hKey, GUID, 0, KEY_READ, &hCLSIDKey);
if (lResult != ERROR_SUCCESS) {
wprintf(L"[-] Error getting GUID path\n");
RegCloseKey(hKey);
return FALSE;
}
// Read the value of HKLM's InProcServer32
lResult = RegGetValueW(hCLSIDKey, (LPCWSTR)L"InProcServer32", NULL, RRF_RT_ANY, NULL, (PVOID)&name, &nameLength);
if (lResult != ERROR_SUCCESS) {
wprintf(L"[-] Error getting InProcServer32 value: %d\n", lResult);
RegCloseKey(hKey);
RegCloseKey(hCLSIDKey);
return FALSE;
}
*DLLName = name;
return TRUE;
}
Then:
wchar_t* DLLName = new wchar_t[MAX_PATH];
if (!FindOriginalCOMServer((wchar_t*)lplpsz, &DLLName))
{
wprintf(L"[-] Couldn't find original COM server\n");
return S_FALSE;
}
wprintf("[+] Found original COM server: %s\n", DLLName);
HMODULE hDLL = LoadLibraryW(DLLName);

DLLName will point to a local char array in FindOriginalCOMServer, which will no longer exist once that function returns.
You should pass DLLName to FindOriginalCOMServer() as a wchar_t* (one pointer, not two) then get rid of name and work with DLLName directly. Or, you could use wcscpy_s() to copy the string from name to DLLName.

Related

C++ Win32 Getting a registry key

const char* Launcher::GetProjectName()
{
PVOID data;
LPDWORD pcbData;
HKEY OpenResult;
LSTATUS status = RegOpenKeyEx(HKEY_CURRENT_USER, L"Environment", NULL, KEY_READ, &OpenResult);
if (status != ERROR_SUCCESS)
{
LOG(ERROR) << "Could not found registry key 'Environment'";
}
else
{
LPCWSTR project_name_key = L"project_name";
DWORD data_type;
WCHAR value[255];
PVOID pvData = value;
DWORD size = sizeof(value);
status = RegGetValue(OpenResult, NULL, project_name_key, RRF_RT_ANY, &data_type, pvData, &size);
if (status != ERROR_SUCCESS)
{
LOG(ERROR) << "Could not found registry value 'project_name'";
}
else
{
switch (data_type)
{
case REG_DWORD:
wprintf(L"Value data: %x\n", *(DWORD*)pvData);
break;
case REG_SZ:
wprintf(L"Value data: %s\n", (PWSTR)pvData);
}
}
RegCloseKey(OpenResult);
}
return 0;
}
I'm trying to get this registry key I made named "project_name" and return it as a char* or a std::string. However, I'm getting garbage data in pvData. What am I doing wrong here? I've seen some other stackoverflow posts and tried to replicate their setup as well but nothing is working. My entire goal here is to retrieve an environment variable using the windows registry.
I think there's a mismatch of ANSI and Unicode expectations. Your code is likely compiling for ANSI, but you're passing a wide-char buffer. Let's just explicitly call the A version of the Registry functions so you can stay in the ANSI string space.
Instead of this:
WCHAR value[255];
PVOID pvData = value;
DWORD size = sizeof(value);
status = RegGetValue(OpenResult, NULL, project_name_key, RRF_RT_ANY, &data_type, pvData, &size);
Use this:
char value[255];
DWORD size = sizeof(value);
status = RegGetValueA(OpenResult, NULL, project_name_key, RRF_RT_ANY, &data_type, value, &size);
Then, return a std::string as follows:
Declare your function to return a string, not a pointer:
const std::string Launcher::GetProjectName()
Then simply return value as a string;
return std::string(value);

Returning invalid data from RegQueryValueEx() DWORD

I'm trying to read a DWORD value from the registry. In the registry, it's stored as 0x00000068 (104). When I read the value from the registry, I'm getting a very large number (3435973836). Any help is appreciated!
DWORD getRecentId(PDWORD id) {
HKEY hKey;
LONG lRes = RegOpenKeyEx(HKEY_CURRENT_USER, _T("SOFTWARE\\My App\\Feed Reader"), 0, KEY_QUERY_VALUE, &hKey);
if (!lRes == ERROR_SUCCESS)
{
RegCloseKey(hKey);
return ERROR_FILE_NOT_FOUND;
}
DWORD dwSize = sizeof(DWORD);
lRes = RegQueryValueEx(hKey, _T("Latest"), NULL, NULL, (LPBYTE)&id, &dwSize);
if (!lRes == ERROR_SUCCESS)
{
RegCloseKey(hKey);
return ERROR_NOT_ENOUGH_MEMORY;
}
RegCloseKey(hKey);
return lRes;
}
3435973836 is a magic number. Convert it to hex to get 0xcccccccc. When you see that back in the Visual Studio debugger then you know that you are using an uninitialized variable.
It is, using &id was wrong. That alters the pointer, not the pointed-to value. Use id instead.

Add Application to Startup (Registry)

I'm trying to add my software to registry, I have found some pieces of the codes I can use but not full working code C/C++ is new to me and can't create it on my own. But here is the basic idea: Check if reg key set if not create it.
I was able to get my program location using this code:
TCHAR szPath[MAX_PATH];
GetModuleFileName(NULL,szPath,MAX_PATH);
And was able to create the key with: (Not sure if it's the right way)
HKEY newValue;
RegOpenKey(HKEY_CURRENT_USER,"Software\\Microsoft\\Windows\\CurrentVersion\\Run",&newValue);
RegSetValueEx(newValue,"myprogram",0,REG_SZ,(LPBYTE)szPath,sizeof(szPath));
RegCloseKey(newValue);
return 0;
What is missing, A small check if the key isn't already there...
Thank you!
Here's some code that likely does what you want. Call RegisterProgram for your EXE to self-register itself for automatically being started when the user logs in. This function calls GetModuleFileName and then invokes another helper function called RegisterMyProgramForStartup that does the writing to the registry.
Call IsMyProgramRegisteredForStartup(L"My_Program") to detect if the registration actually exists and appears valid.
One quick note. The performance impact of checking to see if the key exists before actually writing it out again is negligible. You could just call RegisterProgram blindly and it will overwrite the key if it already exists. Detecting if the registration exists is useful for initializing your UI checkbox that enables or disables auto-start. (You are giving your users a choice, right? Because I hate apps that automatically install themselves to run automatically without giving me a choice.)
BOOL IsMyProgramRegisteredForStartup(PCWSTR pszAppName)
{
HKEY hKey = NULL;
LONG lResult = 0;
BOOL fSuccess = TRUE;
DWORD dwRegType = REG_SZ;
wchar_t szPathToExe[MAX_PATH] = {};
DWORD dwSize = sizeof(szPathToExe);
lResult = RegOpenKeyExW(HKEY_CURRENT_USER, L"Software\\Microsoft\\Windows\\CurrentVersion\\Run", 0, KEY_READ, &hKey);
fSuccess = (lResult == 0);
if (fSuccess)
{
lResult = RegGetValueW(hKey, NULL, pszAppName, RRF_RT_REG_SZ, &dwRegType, szPathToExe, &dwSize);
fSuccess = (lResult == 0);
}
if (fSuccess)
{
fSuccess = (wcslen(szPathToExe) > 0) ? TRUE : FALSE;
}
if (hKey != NULL)
{
RegCloseKey(hKey);
hKey = NULL;
}
return fSuccess;
}
BOOL RegisterMyProgramForStartup(PCWSTR pszAppName, PCWSTR pathToExe, PCWSTR args)
{
HKEY hKey = NULL;
LONG lResult = 0;
BOOL fSuccess = TRUE;
DWORD dwSize;
const size_t count = MAX_PATH*2;
wchar_t szValue[count] = {};
wcscpy_s(szValue, count, L"\"");
wcscat_s(szValue, count, pathToExe);
wcscat_s(szValue, count, L"\" ");
if (args != NULL)
{
// caller should make sure "args" is quoted if any single argument has a space
// e.g. (L"-name \"Mark Voidale\"");
wcscat_s(szValue, count, args);
}
lResult = RegCreateKeyExW(HKEY_CURRENT_USER, L"Software\\Microsoft\\Windows\\CurrentVersion\\Run", 0, NULL, 0, (KEY_WRITE | KEY_READ), NULL, &hKey, NULL);
fSuccess = (lResult == 0);
if (fSuccess)
{
dwSize = (wcslen(szValue)+1)*2;
lResult = RegSetValueExW(hKey, pszAppName, 0, REG_SZ, (BYTE*)szValue, dwSize);
fSuccess = (lResult == 0);
}
if (hKey != NULL)
{
RegCloseKey(hKey);
hKey = NULL;
}
return fSuccess;
}
void RegisterProgram()
{
wchar_t szPathToExe[MAX_PATH];
GetModuleFileNameW(NULL, szPathToExe, MAX_PATH);
RegisterMyProgramForStartup(L"My_Program", szPathToExe, L"-foobar");
}
int _tmain(int argc, _TCHAR* argv[])
{
RegisterProgram();
IsMyProgramRegisteredForStartup(L"My_Program");
return 0;
}
To check whether or not the value exists, call RegQueryValueEx.
LONG retval = RegQueryValueEx(hKey, "myprogram", NULL, NULL, NULL, NULL);
Note that what you called newValue is actually a key rather than a value. To avoid confusion you should name it such. I used the name hKey.
Then to check whether or not the value exists, compare retval against ERROR_SUCCESS as described in the documentation.
The other problem with your code is that there is absolutely no error checking. I'll leave that to you to address.
You forget to write an argument about security access

Save Me Simple Add to Startup via Registry [duplicate]

I'm trying to add my software to registry, I have found some pieces of the codes I can use but not full working code C/C++ is new to me and can't create it on my own. But here is the basic idea: Check if reg key set if not create it.
I was able to get my program location using this code:
TCHAR szPath[MAX_PATH];
GetModuleFileName(NULL,szPath,MAX_PATH);
And was able to create the key with: (Not sure if it's the right way)
HKEY newValue;
RegOpenKey(HKEY_CURRENT_USER,"Software\\Microsoft\\Windows\\CurrentVersion\\Run",&newValue);
RegSetValueEx(newValue,"myprogram",0,REG_SZ,(LPBYTE)szPath,sizeof(szPath));
RegCloseKey(newValue);
return 0;
What is missing, A small check if the key isn't already there...
Thank you!
Here's some code that likely does what you want. Call RegisterProgram for your EXE to self-register itself for automatically being started when the user logs in. This function calls GetModuleFileName and then invokes another helper function called RegisterMyProgramForStartup that does the writing to the registry.
Call IsMyProgramRegisteredForStartup(L"My_Program") to detect if the registration actually exists and appears valid.
One quick note. The performance impact of checking to see if the key exists before actually writing it out again is negligible. You could just call RegisterProgram blindly and it will overwrite the key if it already exists. Detecting if the registration exists is useful for initializing your UI checkbox that enables or disables auto-start. (You are giving your users a choice, right? Because I hate apps that automatically install themselves to run automatically without giving me a choice.)
BOOL IsMyProgramRegisteredForStartup(PCWSTR pszAppName)
{
HKEY hKey = NULL;
LONG lResult = 0;
BOOL fSuccess = TRUE;
DWORD dwRegType = REG_SZ;
wchar_t szPathToExe[MAX_PATH] = {};
DWORD dwSize = sizeof(szPathToExe);
lResult = RegOpenKeyExW(HKEY_CURRENT_USER, L"Software\\Microsoft\\Windows\\CurrentVersion\\Run", 0, KEY_READ, &hKey);
fSuccess = (lResult == 0);
if (fSuccess)
{
lResult = RegGetValueW(hKey, NULL, pszAppName, RRF_RT_REG_SZ, &dwRegType, szPathToExe, &dwSize);
fSuccess = (lResult == 0);
}
if (fSuccess)
{
fSuccess = (wcslen(szPathToExe) > 0) ? TRUE : FALSE;
}
if (hKey != NULL)
{
RegCloseKey(hKey);
hKey = NULL;
}
return fSuccess;
}
BOOL RegisterMyProgramForStartup(PCWSTR pszAppName, PCWSTR pathToExe, PCWSTR args)
{
HKEY hKey = NULL;
LONG lResult = 0;
BOOL fSuccess = TRUE;
DWORD dwSize;
const size_t count = MAX_PATH*2;
wchar_t szValue[count] = {};
wcscpy_s(szValue, count, L"\"");
wcscat_s(szValue, count, pathToExe);
wcscat_s(szValue, count, L"\" ");
if (args != NULL)
{
// caller should make sure "args" is quoted if any single argument has a space
// e.g. (L"-name \"Mark Voidale\"");
wcscat_s(szValue, count, args);
}
lResult = RegCreateKeyExW(HKEY_CURRENT_USER, L"Software\\Microsoft\\Windows\\CurrentVersion\\Run", 0, NULL, 0, (KEY_WRITE | KEY_READ), NULL, &hKey, NULL);
fSuccess = (lResult == 0);
if (fSuccess)
{
dwSize = (wcslen(szValue)+1)*2;
lResult = RegSetValueExW(hKey, pszAppName, 0, REG_SZ, (BYTE*)szValue, dwSize);
fSuccess = (lResult == 0);
}
if (hKey != NULL)
{
RegCloseKey(hKey);
hKey = NULL;
}
return fSuccess;
}
void RegisterProgram()
{
wchar_t szPathToExe[MAX_PATH];
GetModuleFileNameW(NULL, szPathToExe, MAX_PATH);
RegisterMyProgramForStartup(L"My_Program", szPathToExe, L"-foobar");
}
int _tmain(int argc, _TCHAR* argv[])
{
RegisterProgram();
IsMyProgramRegisteredForStartup(L"My_Program");
return 0;
}
To check whether or not the value exists, call RegQueryValueEx.
LONG retval = RegQueryValueEx(hKey, "myprogram", NULL, NULL, NULL, NULL);
Note that what you called newValue is actually a key rather than a value. To avoid confusion you should name it such. I used the name hKey.
Then to check whether or not the value exists, compare retval against ERROR_SUCCESS as described in the documentation.
The other problem with your code is that there is absolutely no error checking. I'll leave that to you to address.
You forget to write an argument about security access

Delete a registry key recursively

I need to remove a subtree in the Windows registry under Windows Mobile 6. The RegDeleteTree function is not available, and SHDeleteKey is (apparently) not available in any static library under the WM6 SDK, though the declaration is available in shlwapi.h.
I tried to get it from shlwapi.dll, like
typedef DWORD (__stdcall *SHDeleteKey_Proc) (HKEY, LPCWSTR);
SHDeleteKey_Proc procSHDeleteKey;
HINSTANCE shlwapidll = ::LoadLibrary(_T("shlwapi.dll"));
if(shlwapidll) {
procSHDeleteKey =
(SHDeleteKey_Proc)GetProcAddress(shlwapidll,_T("SHDeleteKeyW"));
ASSERT(procSHDeleteKey);
}
But I hit the assert.
Is there a nice way to delete, recursively, a Registry key (empty or not) under Windows Mobile?
I guess I found the answer myself in MSDN. It puzzles me that the functionality is not available through the SDK, though...
I put the code from MSDN here as well, just for the record:
//*************************************************************
//
// RegDelnodeRecurse()
//
// Purpose: Deletes a registry key and all it's subkeys / values.
//
// Parameters: hKeyRoot - Root key
// lpSubKey - SubKey to delete
//
// Return: TRUE if successful.
// FALSE if an error occurs.
//
//*************************************************************
BOOL RegDelnodeRecurse (HKEY hKeyRoot, LPTSTR lpSubKey)
{
LPTSTR lpEnd;
LONG lResult;
DWORD dwSize;
TCHAR szName[MAX_PATH];
HKEY hKey;
FILETIME ftWrite;
// First, see if we can delete the key without having
// to recurse.
lResult = RegDeleteKey(hKeyRoot, lpSubKey);
if (lResult == ERROR_SUCCESS)
return TRUE;
lResult = RegOpenKeyEx (hKeyRoot, lpSubKey, 0, KEY_READ, &hKey);
if (lResult != ERROR_SUCCESS)
{
if (lResult == ERROR_FILE_NOT_FOUND) {
printf("Key not found.\n");
return TRUE;
}
else {
printf("Error opening key.\n");
return FALSE;
}
}
// Check for an ending slash and add one if it is missing.
lpEnd = lpSubKey + lstrlen(lpSubKey);
if (*(lpEnd - 1) != TEXT('\\'))
{
*lpEnd = TEXT('\\');
lpEnd++;
*lpEnd = TEXT('\0');
}
// Enumerate the keys
dwSize = MAX_PATH;
lResult = RegEnumKeyEx(hKey, 0, szName, &dwSize, NULL,
NULL, NULL, &ftWrite);
if (lResult == ERROR_SUCCESS)
{
do {
StringCchCopy (lpEnd, MAX_PATH*2, szName);
if (!RegDelnodeRecurse(hKeyRoot, lpSubKey)) {
break;
}
dwSize = MAX_PATH;
lResult = RegEnumKeyEx(hKey, 0, szName, &dwSize, NULL,
NULL, NULL, &ftWrite);
} while (lResult == ERROR_SUCCESS);
}
lpEnd--;
*lpEnd = TEXT('\0');
RegCloseKey (hKey);
// Try again to delete the key.
lResult = RegDeleteKey(hKeyRoot, lpSubKey);
if (lResult == ERROR_SUCCESS)
return TRUE;
return FALSE;
}
//*************************************************************
//
// RegDelnode()
//
// Purpose: Deletes a registry key and all it's subkeys / values.
//
// Parameters: hKeyRoot - Root key
// lpSubKey - SubKey to delete
//
// Return: TRUE if successful.
// FALSE if an error occurs.
//
//*************************************************************
BOOL RegDelnode (HKEY hKeyRoot, LPTSTR lpSubKey)
{
TCHAR szDelKey[MAX_PATH*2];
StringCchCopy (szDelKey, MAX_PATH*2, lpSubKey);
return RegDelnodeRecurse(hKeyRoot, szDelKey);
}
The second argument of GetProcAddress is a LPCSTR (that is, it is not a LPCTSTR). So remove the _T() and try this:
GetProcAddress(shlwapidll, "SHDeleteKeyW");
Does that help solve the problem?
You're looking for the RegDeleteTree() function. Just replace RegDeleteKey with it.
Apparently, it took them a while to figure it out, so if you want to support XP or older, you need to have your own implementation of it.