Program crashes when SetupDiGetDeviceInterfaceDetail is called - c++

I'm trying to get the path of a device by using the SetupDiGetDeviceInterfaceDetail() function, but it crashes everytime I call it. I've have been working on this for over 12 hours but still couldn't find out what is wrong with it... Can someone see if they can find what is actually causing this to happen? Heres the code:
//DeviceManager.h
#include <windows.h>
//#include <hidsdi.h>
#include <setupapi.h>
#include <iostream>
#include <cfgmgr32.h>
#include <tchar.h>
#include <devpkey.h>
#include <string>
extern "C"{
#include <hidsdi.h>
}
//#pragma comment (lib, "setupapi.lib")
class DeviceManager
{
public:
DeviceManager();
~DeviceManager();
void ListAllDevices();
void GetDeviceHandler();
//HANDLE PSMove;
//byte reportBuffer[57];
GUID guid;
//private:
HDEVINFO deviceInfoSet; //A list of all the devices
SP_DEVINFO_DATA deviceInfoData; //A device from deviceInfoSet
SP_DEVICE_INTERFACE_DATA deviceInterfaceData;
SP_DEVICE_INTERFACE_DETAIL_DATA deviceInterfaceDetailedData;
};
//DeviceManager.cpp
#include"DeviceManager.h"
DeviceManager::DeviceManager()
{
//deviceInterfaceData = new SP_DEVICE_INTERFACE_DATA;
//deviceInterfaceDetailedData = new SP_DEVICE_INTERFACE_DETAIL_DATA;
HidD_GetHidGuid(&guid);
deviceInfoSet = SetupDiGetClassDevs(&guid, NULL, NULL, DIGCF_PRESENT|DIGCF_DEVICEINTERFACE); //Gets all Devices
GetDeviceHandler();
}
DeviceManager::~DeviceManager()
{
}
void DeviceManager::ListAllDevices()
{
DWORD deviceIndex = 0;
deviceInfoData.cbSize = sizeof(deviceInfoData);
while(SetupDiEnumDeviceInfo(deviceInfoSet, deviceIndex, &deviceInfoData))
{
deviceInfoData.cbSize = sizeof(deviceInfoData);
ULONG tcharSize;
CM_Get_Device_ID_Size(&tcharSize, deviceInfoData.DevInst, 0);
TCHAR* deviceIDBuffer = new TCHAR[tcharSize]; //the device ID will be stored in this array, so the tcharSize needs to be big enough to hold all the info.
//Or we can use MAX_DEVICE_ID_LEN, which is 200
CM_Get_Device_ID(deviceInfoData.DevInst, deviceIDBuffer, MAX_PATH, 0); //gets the devices ID - a long string that looks like a file path.
std::cout << deviceIDBuffer << std::endl;
deviceIndex++;
}
}
void DeviceManager::GetDeviceHandler()
{
DWORD deviceIndex = 0;
SP_DEVINFO_DATA deviceInfoData;
SP_DEVICE_INTERFACE_DATA deviceInterfaceData;
SP_DEVICE_INTERFACE_DETAIL_DATA deviceInterfaceDetailedData;
deviceInfoData.cbSize = sizeof(deviceInfoData);
while(SetupDiEnumDeviceInfo(deviceInfoSet, deviceIndex, &deviceInfoData))
{
TCHAR deviceID[MAX_DEVICE_ID_LEN];
CM_Get_Device_ID(deviceInfoData.DevInst, deviceID, MAX_DEVICE_ID_LEN, 0);
//std::cout << deviceID << std::endl;
deviceInterfaceData.cbSize = sizeof(SP_DEVICE_INTERFACE_DATA);
if(SetupDiEnumDeviceInterfaces(deviceInfoSet, &deviceInfoData, &guid, 0, &deviceInterfaceData))
{
DWORD bufferLength = 0;
//deviceInterfaceData.cbSize = sizeof(SP_DEVICE_INTERFACE_DATA);
deviceInterfaceData.cbSize = 2048;
//std::cout << "it works not" << std::endl;
if(SetupDiGetDeviceInterfaceDetail(deviceInfoSet, &deviceInterfaceData, NULL, 0, &bufferLength, NULL))
{
//deviceInterfaceData.cbSize = sizeof(bufferLength);
std::cout << "It works!" << std::endl;
}
else
{
std::cout << GetLastError() << std::endl;
}
}
else
{
//std::cout << GetLastError() << std::endl;
}
deviceIndex++;
}
}
//mainapp.cpp
#pragma once
int main()
{
DeviceManager deviceManager;
return 0;
}
The SetupDiGetDeviceInterfaceDetail function is called in the GetDeviceHandler() function of DeviceManager.
Please help. Thanks.
UPDATE: I have found out that it failed on the first SetupDiGetDeviceInterfaceDetail and is returning a 122 error (ERROR_INSUFFICIENT_BUFFER). But I am only trying to get the required buffer size, so how can this be??
UPDATE 2: right, I have changed the function a bit (see above code) by setting the deviceInterfaceData.cbsize to 2048 (a huge space for testing purposes) and now I'm getting a ERROR_INVALID_PARAMETER. This is getting more and more confusing... How can the parameters I've given is invalid? Just doesn't make sense. The only difference is I passed in References instead of Pointers because otherwise I will get a access violation error...

Having found this topic, I'd like to share my problem that using exactly the same source, I got ERROR_INVALID_USER_BUFFER from the call.
The reason was the line:
deviceInterfaceDetailedData->cbSize =
sizeof(SP_INTERFACE_DEVICE_DETAIL_DATA);
which on my quadbyte aligned compiler set the value 8 instead of the required value 5.

You're not allocating memory properly for the SP_DEVICE_INTERFACE_DETAIL_DATA.
Remove SP_DEVICE_INTERFACE_DETAIL_DATA deviceInterfaceDetailedData; and try putting this inside your if block:
// Get the required bufferLength
SetupDiGetDeviceInterfaceDetail(deviceInfoSet,
&deviceInterfaceData,
nullptr,
0,
&bufferLength,
nullptr);
if(GetLastError() != ERROR_INSUFFICIENT_BUFFER)
{
std::cout << "Failed to get bufferLength. Error "
<< GetLastError() << '\n';
return;
}
// Create device interface detailed information struct pointer
// and allocate memory to it.
PSP_DEVICE_INTERFACE_DETAIL_DATA deviceInterfaceDetailedData(nullptr);
deviceInterfaceDetailedData =
static_cast<PSP_INTERFACE_DEVICE_DETAIL_DATA>(malloc(bufferLength));
if(deviceInterfaceDetailedData == nullptr)
{
std::cout << "Failed to allocate memory. Error "
<< GetLastError() << '\n';
return;
}
deviceInterfaceDetailedData->cbSize =
sizeof(SP_INTERFACE_DEVICE_DETAIL_DATA);
// Get detailed information
if(SetupDiGetDeviceInterfaceDetail(deviceInfoSet,
&deviceInterfaceData,
deviceInterfaceDetailedData,
bufferLength,
&bufferLength,
nullptr))
{
//deviceInterfaceData.cbSize = sizeof(bufferLength);
std::cout << "It works!" << std::endl;
}
else
{
std::cout << GetLastError() << std::endl;
}
free(deviceInterfaceDetailedData);
I haven't looked at the rest of the code, it may have errors too, but this answers your original question.

This is according to MSDN definition:
Get the required buffer size. Call SetupDiGetDeviceInterfaceDetail with a NULLDeviceInterfaceDetailData pointer, a DeviceInterfaceDetailDataSize of zero, and a valid RequiredSize variable. In response to such a call, this function returns the required buffer size at RequiredSize and fails with GetLastError returning ERROR_INSUFFICIENT_BUFFER.
So, after ERROR_INSUFFICIENT_BUFFER error just use requiredSize value.

Related

Getting all services and their path to exe

Get list of windows services and print name, status, path to exe
the above statement needs to be solved, I am aware we enum services to find.....since I am beginner ,I don't understand how to retrieve all the path to exe.
this is what I knew
#include <Windows.h>
#include <iostream>
int main()
{
SC_HANDLE sHandle;
LPQUERY_SERVICE_CONFIG lpServiceConfig = NULL;
DWORD cbBufSize = 100;
LPDWORD bytesNeeded = NULL;
sHandle = OpenSCManager(NULL,NULL,SC_MANAGER_ALL_ACCESS);
sHandle = OpenService(sHandle, "YOU SERVICE NAME",SERVICE_ALL_ACCESS);
QueryServiceConfig(sHandle,lpServiceConfig,cbBufSize,bytesNeeded);
std::cout << lpServiceConfig->lpBinaryPathName << std::endl;
}
You need to use EnumServiceStatus() to query which services are installed. You can then open each service to query its EXE path.
Also, your code is leaking resources and memory.
Try something more like this:
#include <Windows.h>
#include <iostream>
#include <vector>
int main()
{
DWORD bytesNeeded = 0;
DWORD numServices = 0;
DWORD resumeHandle = 0;
SC_HANDLE hSCManager = OpenSCManager(NULL, NULL, SC_MANAGER_ENUMERATE_SERVICE);
if (!hSCManager) ...
EnumServicesStatus(hSCManager, SERVICE_WIN32, SERVICE_STATE_ALL, NULL, 0, &bytesNeeded, &numServices, &resumeHandle);
if (GetLastError() != ERROR_INSUFFICIENT_BUFFER) ...
std::vector<BYTE> enumBuffer(bytesNeeded);
LPENUM_SERVICE_STATUS pEnum = reinterpret_cast<LPENUM_SERVICE_STATUS>(enumBuffer.data());
if (!EnumServicesStatus(hSCManager, SERVICE_WIN32, SERVICE_STATE_ALL, pEnum, bytesNeeded, &bytesNeeded, &numServices, &resumeHandle)) ...
for(DWORD idx = 0; idx < numServices; ++idx)
{
std::cout << pEnum[idx].lpServiceName << " (" << pEnum[idx].lpDisplayName << ")" << std::endl;
// use/display pEnum[idx].ServiceStatus as needed ...
SC_HANDLE hService = OpenService(hSCManager, pEnum[idx].lpServiceName, SERVICE_QUERY_CONFIG);
if (!hService) ...
QueryServiceConfig(hSerivce, NULL, 0, &bytesNeeded);
if (GetLastError() != ERROR_INSUFFICIENT_BUFFER) ...
std::vector<BYTE> configBuffer(bytesNeeded);
LPQUERY_SERVICE_CONFIG lpServiceConfig = reinterpret_cast<LPQUERY_SERVICE_CONFIG>(configBuffer.data());
if (!QueryServiceConfig(hSerivce, lpServiceConfig, bytesNeeded, &bytesNeeded)) ...
std::cout << lpServiceConfig->lpBinaryPathName << std::endl;
CloseServiceHandle(hService);
}
CloseServiceHandle(hSCManager);
}

Enumerate all file type associations

I want to list all the file type associations app names. My code:
#include <windows.h>
#include <shlwapi.h>
#include <ShlObj.h>
#include <iostream>
#pragma comment(lib, "shlwapi.lib")
int main()
{
IQueryAssociations *iQueryAssoc = nullptr;
HRESULT assocHRes = AssocCreate(CLSID_QueryAssociations, IID_IQueryAssociations, reinterpret_cast<void**>(&iQueryAssoc));
if (assocHRes == S_OK) {
HWND hWnd = GetConsoleWindow();
LPCWSTR pszAssoc = L".xls";
HRESULT initAssocHRes = iQueryAssoc->Init(NULL, pszAssoc, NULL, hWnd);
if (initAssocHRes == S_OK) {
TCHAR buffer[1024];
DWORD bufferSize = 1024;
HRESULT getStrAssocHRes = iQueryAssoc->GetString(ASSOCF_NONE, ASSOCSTR_FRIENDLYAPPNAME, NULL, buffer, &bufferSize);
if (getStrAssocHRes == S_OK) {
std::wcout << "App name: " << std::wstring(buffer).c_str() << std::endl;
} else {
std::wcout << "iQueryAssoc GetString failed!" << std::endl;
}
} else {
std::wcout << "iQueryAssoc Init failed!" << std::endl;
}
} else {
std::wcout << "AssocCreate failed!" << std::endl;
}
iQueryAssoc->Release();
system("PAUSE");
return 0;
}
My code works but it displays app name only for the ".xls" extension. I think, I need to use the while (iQueryAssoc->QueryInterface()) to get all of them. Is there any example how to use it? Should I call init method first and then QueryInterface method or just call QueryInterface method without init method?
Additionally, I have found the SHAssocEnumHandlers method:
IEnumAssocHandlers *pEnumHandlers = nullptr;
IAssocHandler *assocHandler = nullptr;
HRESULT initAssocHRes = SHAssocEnumHandlers(NULL, ASSOC_FILTER_NONE, &pEnumHandlers);
if (initAssocHRes == S_OK) {
while (pEnumHandlers->Next(1, &assocHandler, nullptr) == S_OK) {
std::cout << "Test..." << std::endl;
}
} else {
std::cout << "Failed: " << initAssocHRes << std::endl;
}
But for me, it fails with the following error: Failed: -2147024882 E_OUTOFMEMORY - Failed to allocate necessary memory. I think, the issue with: IEnumAssocHandlers are null and not initialized. What method should I use to initialize the IEnumAssocHandlers? Thank you.
I have found, these lines of code leads to E_OUTOFMEMORY issue:
IEnumAssocHandlers *pEnumHandlers = NULL;
HRESULT initAssocHRes = SHAssocEnumHandlers(NULL, ASSOC_FILTER_RECOMMENDED, &pEnumHandlers);
Also, I got this warning:
Any ideas? Thank you.
Updated code:
#include <windows.h>
#include <shlwapi.h>
#include <ShlObj.h>
#include <iostream>
#include "hresinfo.h"
#pragma comment(lib, "shlwapi.lib")
#pragma comment(lib, "shell32.lib")
int main()
{
IEnumAssocHandlers *pEnumHandlers = nullptr;
HRESULT initAssocHRes = SHAssocEnumHandlers(NULL, ASSOC_FILTER_NONE, reinterpret_cast<IEnumAssocHandlers**>(&pEnumHandlers));
if (initAssocHRes == S_OK) {
IAssocHandler *pAssocHandler = nullptr;
LPWSTR pszName = nullptr;
while (pEnumHandlers->Next(1, &pAssocHandler, NULL) == S_OK) {
if (pAssocHandler) {
pAssocHandler->GetUIName(&pszName);
printf_s("%S \n", pszName);
}
}
if (pAssocHandler) {
pAssocHandler->Release();
}
} else {
HRESInfo::getErrorMsg(initAssocHRes);
}
if (pEnumHandlers) {
pEnumHandlers->Release();
}
system("PAUSE");
return 0;
}
Screenshot:
You don't say which call is actually failing (so please do so), but if you look at the documentation for IEnumAssocHandlers::Next, it doesn't say anywhere that the third parameter (pceltFetched) can be nullptr, so I would change your code to:
if (initAssocHRes == S_OK) {
ULONG handlers_retrieved = 0;
while (pEnumHandlers->Next(1, &assocHandler, &handlers_retrieved) == S_OK) {
...
Also first parameter to SHAssocEnumHandlers must not be null:
wchar_t *extension = L".jpg";
HRESULT initAssocHRes = SHAssocEnumHandlers(extension, ...

Construct own object from return value of MapViewOfFile()

I want to 'cast' the return value of MapViewOfFile (as far as I know a pointer to void) to my own class, so that I am able work with this object. I know how the memory is structured. The headerSize resides at byte number 4 to byte number 8, a hex value is written in the byte for example hex 47, so the size should be 71 bytes. I want to get 71 as the value of my attribute 'headerSize'. What code has to replace 'TODO' in my snippet? I do not know how to read the bytes and how to create the attributes.
Code in main.cpp:
// MapViewOfFile return a pointer to void, so you need to cast it to a suitable structure
pBuf = (FILE*) MapViewOfFile(hMapFile, FILE_MAP_ALL_ACCESS, 0, 0, BUF_SIZE);
// create object
JobaShm jobaShm(pBuf);
int headerSize = jobaShm.getHeaderSize();
std::cout << " HeaderSize " << headerSize << ";\n";
Code in jobashm.h
#ifndef JOBASHM_H
#define JOBASHM
class JobaShm {
public:
JobaShm(FILE* handle);
int getHeaderSize();
private:
int headerSize;
};
#endif
Code in jobashm.cpp
#include <stdio.h>
#include "jobashm.h"
JobaShm::JobaShm(FILE* handle){
// TODO
}
int JobaShm::getHeaderSize(){
return headerSize;
}
UPDATE: Due to this tutorial http://www.cplusplus.com/forum/general/54381/ I am trying to cast the return value of MapViewOfFile in my own struct.
main.cpp
struct Shm {
int firstByte;
};
int main(void){
std::cout << "*** Start SharedMemory ***\n";
HANDLE hMapFile;
hMapFile = OpenFileMapping(FILE_MAP_ALL_ACCESS, FALSE, szName);
if (hMapFile == NULL){
MessageBox(NULL, TEXT("Could not open file mapping object"), TEXT("ERROR"), MB_OK);
return 1;
}
Shm * pBuf = (Shm *) MapViewOfFile(hMapFile, FILE_MAP_ALL_ACCESS, 0, 0, BUF_SIZE); // ggf. besser size_of Shm, statt BUF_SIZE
std::cout << " Debug " << pBuf->firstByte << ";\n";
UnmapViewOfFile(&pBuf);
CloseHandle(hMapFile);
std::cout << "*** close app by typing a number. ***\n";
int a = 0;
cin >> a;
return 0;
}
I think you have to read more about MapViewOfFile.
http://msdn.microsoft.com/en-us/library/windows/desktop/aa366551(v=vs.85).aspx
It returns a pointer to the data.
LPCTSTR pBuf;
pBuf = (LPTSTR) MapViewOfFile(hMapFile, FILE_MAP_ALL_ACCESS, 0, 0, BUF_SIZE);
JobaShm(pBuf)
Then since you know what the data is you should create a structure for it and cast it.
struct FileData {
int space;
int headerSize;
// etc...
}
JobaShm::JobaShm(LPTSTR* pBuf) {
FileData fd;
CopyMemory((PVOID)pBuf, &fd, sizeof(fd));
headerSize = fd.headerSize;
}

Converting LPBYTE into String

I'm querying data from the registry and it's being outputted as LPBYTE, and this is where i'm stuck. I need to convert the LPBYTE into a type of data that I can manipulate such as a String.
This is my code so far
HKEY hk;
string poolID;
DWORD dwSize = 0;
DWORD dwDataType = 0;
DWORD dwValue;
LPBYTE lpValue = NULL;
CA2W registryLocation("Software\\Example");
// Check registry if exists, otherwise create.
LONG openReg = RegOpenKeyEx(HKEY_CURRENT_USER, registryLocation, 0, KEY_QUERY_VALUE, &hk);
if (openReg==ERROR_SUCCESS) { } else { cout << "Error (Could not open/create Registry Location)\n"; }
// Get buffer size
LONG getRegBuf = RegQueryValueExA(hk, "", 0, &dwDataType, lpValue, &dwSize);
if (getRegBuf==ERROR_SUCCESS) { cout << "Got reg key buf size\n"; } else { cout << "Error (registry key does not exist)/n"; intro(); }
lpValue = (LPBYTE)malloc(dwSize);
// Open reg value
LONG getReg = RegQueryValueExA(hk, "", 0, &dwDataType, (LPBYTE)&dwValue, &dwSize);
if (getReg==ERROR_SUCCESS) { cout << "Successful\n"; } else { cout << "Error\n"; }
cout << dwValue;
Any help or code examples will be much appreciated.
You need to declare lpValue to be char*.
char* lpValue;
Then allocate it with a call to new.
lpValue = new char[dwSize+1];
Allocate an extra element in case the registry data is mal-formed and is missing a null-terminator. That is something that can happen. Then set the last element to \0:
lpValue[dwSize] = '\0';
Then get the value:
LONG getReg = RegQueryValueExA(..., (LPBYTE)&dwValue, ...);
Deallocate using delete[]:
delete[] lpValue;

How to read a value from the Windows registry

Given the key for some registry value (e.g. HKEY_LOCAL_MACHINE\blah\blah\blah\foo) how can I:
Safely determine that such a key exists.
Programmatically (i.e. with code) get its value.
I have absolutely no intention of writing anything back to the registry (for the duration of my career if I can help it). So we can skip the lecture about every molecule in my body exploding at the speed of light if I write to the registry incorrectly.
Prefer answers in C++, but mostly just need to know what the special Windows API incantation to get at the value is.
Here is some pseudo-code to retrieve the following:
If a registry key exists
What the default value is for that registry key
What a string value is
What a DWORD value is
Example code:
Include the library dependency: Advapi32.lib
HKEY hKey;
LONG lRes = RegOpenKeyExW(HKEY_LOCAL_MACHINE, L"SOFTWARE\\Perl", 0, KEY_READ, &hKey);
bool bExistsAndSuccess (lRes == ERROR_SUCCESS);
bool bDoesNotExistsSpecifically (lRes == ERROR_FILE_NOT_FOUND);
std::wstring strValueOfBinDir;
std::wstring strKeyDefaultValue;
GetStringRegKey(hKey, L"BinDir", strValueOfBinDir, L"bad");
GetStringRegKey(hKey, L"", strKeyDefaultValue, L"bad");
LONG GetDWORDRegKey(HKEY hKey, const std::wstring &strValueName, DWORD &nValue, DWORD nDefaultValue)
{
nValue = nDefaultValue;
DWORD dwBufferSize(sizeof(DWORD));
DWORD nResult(0);
LONG nError = ::RegQueryValueExW(hKey,
strValueName.c_str(),
0,
NULL,
reinterpret_cast<LPBYTE>(&nResult),
&dwBufferSize);
if (ERROR_SUCCESS == nError)
{
nValue = nResult;
}
return nError;
}
LONG GetBoolRegKey(HKEY hKey, const std::wstring &strValueName, bool &bValue, bool bDefaultValue)
{
DWORD nDefValue((bDefaultValue) ? 1 : 0);
DWORD nResult(nDefValue);
LONG nError = GetDWORDRegKey(hKey, strValueName.c_str(), nResult, nDefValue);
if (ERROR_SUCCESS == nError)
{
bValue = (nResult != 0) ? true : false;
}
return nError;
}
LONG GetStringRegKey(HKEY hKey, const std::wstring &strValueName, std::wstring &strValue, const std::wstring &strDefaultValue)
{
strValue = strDefaultValue;
WCHAR szBuffer[512];
DWORD dwBufferSize = sizeof(szBuffer);
ULONG nError;
nError = RegQueryValueExW(hKey, strValueName.c_str(), 0, NULL, (LPBYTE)szBuffer, &dwBufferSize);
if (ERROR_SUCCESS == nError)
{
strValue = szBuffer;
}
return nError;
}
const CString REG_SW_GROUP_I_WANT = _T("SOFTWARE\\My Corporation\\My Package\\Group I want");
const CString REG_KEY_I_WANT= _T("Key Name");
CRegKey regKey;
DWORD dwValue = 0;
if(ERROR_SUCCESS != regKey.Open(HKEY_LOCAL_MACHINE, REG_SW_GROUP_I_WANT))
{
m_pobLogger->LogError(_T("CRegKey::Open failed in Method"));
regKey.Close();
goto Function_Exit;
}
if( ERROR_SUCCESS != regKey.QueryValue( dwValue, REG_KEY_I_WANT))
{
m_pobLogger->LogError(_T("CRegKey::QueryValue Failed in Method"));
regKey.Close();
goto Function_Exit;
}
// dwValue has the stuff now - use for further processing
Since Windows >=Vista/Server 2008, RegGetValue is available, which is a safer function than RegQueryValueEx. No need for RegOpenKeyEx, RegCloseKey or NUL termination checks of string values (REG_SZ, REG_MULTI_SZ, REG_EXPAND_SZ).
#include <iostream>
#include <string>
#include <exception>
#include <windows.h>
/*! \brief Returns a value from HKLM as string.
\exception std::runtime_error Replace with your error handling.
*/
std::wstring GetStringValueFromHKLM(const std::wstring& regSubKey, const std::wstring& regValue)
{
size_t bufferSize = 0xFFF; // If too small, will be resized down below.
std::wstring valueBuf; // Contiguous buffer since C++11.
valueBuf.resize(bufferSize);
auto cbData = static_cast<DWORD>(bufferSize * sizeof(wchar_t));
auto rc = RegGetValueW(
HKEY_LOCAL_MACHINE,
regSubKey.c_str(),
regValue.c_str(),
RRF_RT_REG_SZ,
nullptr,
static_cast<void*>(valueBuf.data()),
&cbData
);
while (rc == ERROR_MORE_DATA)
{
// Get a buffer that is big enough.
cbData /= sizeof(wchar_t);
if (cbData > static_cast<DWORD>(bufferSize))
{
bufferSize = static_cast<size_t>(cbData);
}
else
{
bufferSize *= 2;
cbData = static_cast<DWORD>(bufferSize * sizeof(wchar_t));
}
valueBuf.resize(bufferSize);
rc = RegGetValueW(
HKEY_LOCAL_MACHINE,
regSubKey.c_str(),
regValue.c_str(),
RRF_RT_REG_SZ,
nullptr,
static_cast<void*>(valueBuf.data()),
&cbData
);
}
if (rc == ERROR_SUCCESS)
{
cbData /= sizeof(wchar_t);
valueBuf.resize(static_cast<size_t>(cbData - 1)); // remove end null character
return valueBuf;
}
else
{
throw std::runtime_error("Windows system error code: " + std::to_string(rc));
}
}
int main()
{
std::wstring regSubKey;
#ifdef _WIN64 // Manually switching between 32bit/64bit for the example. Use dwFlags instead.
regSubKey = L"SOFTWARE\\WOW6432Node\\Company Name\\Application Name\\";
#else
regSubKey = L"SOFTWARE\\Company Name\\Application Name\\";
#endif
std::wstring regValue(L"MyValue");
std::wstring valueFromRegistry;
try
{
valueFromRegistry = GetStringValueFromHKLM(regSubKey, regValue);
}
catch (std::exception& e)
{
std::cerr << e.what();
}
std::wcout << valueFromRegistry;
}
Its parameter dwFlags supports flags for type restriction, filling the value buffer with zeros on failure (RRF_ZEROONFAILURE) and 32/64bit registry access (RRF_SUBKEY_WOW6464KEY, RRF_SUBKEY_WOW6432KEY) for 64bit programs.
The pair RegOpenKey and RegQueryKeyEx will do the trick.
If you use MFC CRegKey class is even more easier solution.
RegQueryValueEx
This gives the value if it exists, and returns an error code ERROR_FILE_NOT_FOUND if the key doesn't exist.
(I can't tell if my link is working or not, but if you just google for "RegQueryValueEx" the first hit is the msdn documentation.)
Typically the register key and value are constants in the program. If so, here is an example how to read a DWORD registry value Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem\LongPathsEnabled:
#include <windows.h>
DWORD val;
DWORD dataSize = sizeof(val);
if (ERROR_SUCCESS == RegGetValueA(HKEY_LOCAL_MACHINE, "SYSTEM\\CurrentControlSet\\Control\\FileSystem", "LongPathsEnabled", RRF_RT_DWORD, nullptr /*type not required*/, &val, &dataSize)) {
printf("Value is %i\n", val);
// no CloseKey needed because it is a predefined registry key
}
else {
printf("Error reading.\n");
}
To adapt for other value types, see https://learn.microsoft.com/en-us/windows/win32/api/winreg/nf-winreg-reggetvaluea for complete spec.
This console app will list all the values and their data from a registry key for most of the potential registry values. There's some weird ones not often used. If you need to support all of them, expand from this example while referencing this Registry Value Type documentation.
Let this be the registry key content you can import from a .reg file format:
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\added\subkey]
"String_Value"="hello, world!"
"Binary_Value"=hex:01,01,01,01
"Dword value"=dword:00001224
"QWord val"=hex(b):24,22,12,00,00,00,00,00
"multi-line val"=hex(7):4c,00,69,00,6e,00,65,00,20,00,30,00,00,00,4c,00,69,00,\
6e,00,65,00,20,00,31,00,00,00,4c,00,69,00,6e,00,65,00,20,00,32,00,00,00,00,\
00
"expanded_val"=hex(2):25,00,55,00,53,00,45,00,52,00,50,00,52,00,4f,00,46,00,49,\
00,4c,00,45,00,25,00,5c,00,6e,00,65,00,77,00,5f,00,73,00,74,00,75,00,66,00,\
66,00,00,00
The console app itself:
#include <Windows.h>
#include <iostream>
#include <string>
#include <locale>
#include <vector>
#include <iomanip>
int wmain()
{
const auto hKey = HKEY_CURRENT_USER;
constexpr auto lpSubKey = TEXT("added\\subkey");
auto openedKey = HKEY();
auto status = RegOpenKeyEx(hKey, lpSubKey, 0, KEY_READ, &openedKey);
if (status == ERROR_SUCCESS) {
auto valueCount = static_cast<DWORD>(0);
auto maxNameLength = static_cast<DWORD>(0);
auto maxValueLength = static_cast<DWORD>(0);
status = RegQueryInfoKey(openedKey, NULL, NULL, NULL, NULL, NULL, NULL,
&valueCount, &maxNameLength, &maxValueLength, NULL, NULL);
if (status == ERROR_SUCCESS) {
DWORD type = 0;
DWORD index = 0;
std::vector<wchar_t> valueName = std::vector<wchar_t>(maxNameLength + 1);
std::vector<BYTE> dataBuffer = std::vector<BYTE>(maxValueLength);
for (DWORD index = 0; index < valueCount; index++) {
DWORD charCountValueName = static_cast<DWORD>(valueName.size());
DWORD charBytesData = static_cast<DWORD>(dataBuffer.size());
status = RegEnumValue(openedKey, index, valueName.data(), &charCountValueName,
NULL, &type, dataBuffer.data(), &charBytesData);
if (type == REG_SZ) {
const auto reg_string = reinterpret_cast<wchar_t*>(dataBuffer.data());
std::wcout << L"Type: REG_SZ" << std::endl;
std::wcout << L"\tName: " << valueName.data() << std::endl;
std::wcout << L"\tData : " << reg_string << std::endl;
}
else if (type == REG_EXPAND_SZ) {
const auto casted = reinterpret_cast<wchar_t*>(dataBuffer.data());
TCHAR buffer[32000];
ExpandEnvironmentStrings(casted, buffer, 32000);
std::wcout << L"Type: REG_EXPAND_SZ" << std::endl;
std::wcout << L"\tName: " << valueName.data() << std::endl;
std::wcout << L"\tData: " << buffer << std::endl;
}
else if (type == REG_MULTI_SZ) {
std::vector<std::wstring> lines;
const auto str = reinterpret_cast<wchar_t*>(dataBuffer.data());
auto line = str;
lines.emplace_back(line);
for (auto i = 0; i < charBytesData / sizeof(wchar_t) - 1; i++) {
const auto c = str[i];
if (c == 0) {
line = str + i + 1;
const auto new_line = reinterpret_cast<wchar_t*>(line);
if (wcsnlen_s(new_line, 1024) > 0)
lines.emplace_back(new_line);
}
}
std::wcout << L"Type: REG_MULTI_SZ" << std::endl;
std::wcout << L"\tName: " << valueName.data() << std::endl;
std::wcout << L"\tData: " << std::endl;
for (size_t i = 0; i < lines.size(); i++) {
std::wcout << L"\t\tLine[" << i + 1 << L"]: " << lines[i] << std::endl;
}
}
if (type == REG_DWORD) {
const auto dword_value = reinterpret_cast<unsigned long*>(dataBuffer.data());
std::wcout << L"Type: REG_DWORD" << std::endl;
std::wcout << L"\tName: " << valueName.data() << std::endl;
std::wcout << L"\tData : " << std::to_wstring(*dword_value) << std::endl;
}
else if (type == REG_QWORD) {
const auto qword_value = reinterpret_cast<unsigned long long*>(dataBuffer.data());
std::wcout << L"Type: REG_DWORD" << std::endl;
std::wcout << L"\tName: " << valueName.data() << std::endl;
std::wcout << L"\tData : " << std::to_wstring(*qword_value) << std::endl;
}
else if (type == REG_BINARY) {
std::vector<uint16_t> bins;
for (auto i = 0; i < charBytesData; i++) {
bins.push_back(static_cast<uint16_t>(dataBuffer[i]));
}
std::wcout << L"Type: REG_BINARY" << std::endl;
std::wcout << L"\tName: " << valueName.data() << std::endl;
std::wcout << L"\tData:";
for (size_t i = 0; i < bins.size(); i++) {
std::wcout << L" " << std::uppercase << std::hex << \
std::setw(2) << std::setfill(L'0') << std::to_wstring(bins[i]);
}
std::wcout << std::endl;
}
}
}
}
RegCloseKey(openedKey);
return 0;
}
Expected console output:
Type: REG_SZ
Name: String_Value
Data : hello, world!
Type: REG_BINARY
Name: Binary_Value
Data: 01 01 01 01
Type: REG_DWORD
Name: Dword value
Data : 4644
Type: REG_DWORD
Name: QWord val
Data : 1188388
Type: REG_MULTI_SZ
Name: multi-line val
Data:
Line[1]: Line 0
Line[2]: Line 1
Line[3]: Line 2
Type: REG_EXPAND_SZ
Name: expanded_val
Data: C:\Users\user name\new_stuff
#include <windows.h>
#include <map>
#include <string>
#include <stdio.h>
#include <string.h>
#include <tr1/stdint.h>
using namespace std;
void printerr(DWORD dwerror) {
LPVOID lpMsgBuf;
FormatMessage(
FORMAT_MESSAGE_ALLOCATE_BUFFER |
FORMAT_MESSAGE_FROM_SYSTEM |
FORMAT_MESSAGE_IGNORE_INSERTS,
NULL,
dwerror,
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language
(LPTSTR) &lpMsgBuf,
0,
NULL
);
// Process any inserts in lpMsgBuf.
// ...
// Display the string.
if (isOut) {
fprintf(fout, "%s\n", lpMsgBuf);
} else {
printf("%s\n", lpMsgBuf);
}
// Free the buffer.
LocalFree(lpMsgBuf);
}
bool regreadSZ(string& hkey, string& subkey, string& value, string& returnvalue, string& regValueType) {
char s[128000];
map<string,HKEY> keys;
keys["HKEY_CLASSES_ROOT"]=HKEY_CLASSES_ROOT;
keys["HKEY_CURRENT_CONFIG"]=HKEY_CURRENT_CONFIG; //DID NOT SURVIVE?
keys["HKEY_CURRENT_USER"]=HKEY_CURRENT_USER;
keys["HKEY_LOCAL_MACHINE"]=HKEY_LOCAL_MACHINE;
keys["HKEY_USERS"]=HKEY_USERS;
HKEY mykey;
map<string,DWORD> valuetypes;
valuetypes["REG_SZ"]=REG_SZ;
valuetypes["REG_EXPAND_SZ"]=REG_EXPAND_SZ;
valuetypes["REG_MULTI_SZ"]=REG_MULTI_SZ; //probably can't use this.
LONG retval=RegOpenKeyEx(
keys[hkey], // handle to open key
subkey.c_str(), // subkey name
0, // reserved
KEY_READ, // security access mask
&mykey // handle to open key
);
if (ERROR_SUCCESS != retval) {printerr(retval); return false;}
DWORD slen=128000;
DWORD valuetype = valuetypes[regValueType];
retval=RegQueryValueEx(
mykey, // handle to key
value.c_str(), // value name
NULL, // reserved
(LPDWORD) &valuetype, // type buffer
(LPBYTE)s, // data buffer
(LPDWORD) &slen // size of data buffer
);
switch(retval) {
case ERROR_SUCCESS:
//if (isOut) {
// fprintf(fout,"RegQueryValueEx():ERROR_SUCCESS:succeeded.\n");
//} else {
// printf("RegQueryValueEx():ERROR_SUCCESS:succeeded.\n");
//}
break;
case ERROR_MORE_DATA:
//what do I do now? data buffer is too small.
if (isOut) {
fprintf(fout,"RegQueryValueEx():ERROR_MORE_DATA: need bigger buffer.\n");
} else {
printf("RegQueryValueEx():ERROR_MORE_DATA: need bigger buffer.\n");
}
return false;
case ERROR_FILE_NOT_FOUND:
if (isOut) {
fprintf(fout,"RegQueryValueEx():ERROR_FILE_NOT_FOUND: registry value does not exist.\n");
} else {
printf("RegQueryValueEx():ERROR_FILE_NOT_FOUND: registry value does not exist.\n");
}
return false;
default:
if (isOut) {
fprintf(fout,"RegQueryValueEx():unknown error type 0x%lx.\n", retval);
} else {
printf("RegQueryValueEx():unknown error type 0x%lx.\n", retval);
}
return false;
}
retval=RegCloseKey(mykey);
if (ERROR_SUCCESS != retval) {printerr(retval); return false;}
returnvalue = s;
return true;
}