I manual map dll and i can't get MODULEINFO for it's working region with GetModuleInformation (it's always answer for me with "Unable to obtain module")?. That happens because that function tries to get data from the module list in the process environment block. But a manually mapped dll is usually not linked in that list unless of course you manually add a new list entry.
It doesn't use the info from the header (or at least not directly).
So i already has dllBase that is hModule. So now i only need to get it's size.
Is any way to get it without GetModuleInformation?
static void someFunc(HINSTANCE hModule)
{
// all the vars we need for the GetModuleInformation call
MODULEINFO modInfo;
HANDLE hProcess = GetCurrentProcess();
if (GetModuleInformation(hProcess, hModule, &modInfo, sizeof(MODULEINFO)))
{
// some work
}
else {
std::cout << "Unable to obtain module" << std::endl;
}
}
if we want get image size for mapped image in self process - we can read it from SizeOfImage member of IMAGE_OPTIONAL_HEADER - this is size of the mapped as image image in memory (not size on disk)
ULONG GetImageSize(PVOID ImageBase = &__ImageBase)
{
if (PIMAGE_NT_HEADERS pinth = RtlImageNtHeader(ImageBase))
{
return pinth->OptionalHeader.SizeOfImage;
}
return 0;
}
Related
Can someone please tell me how to go about creating a maximum of N instances of an application in MFC?
Also, if N instances are running, and one instance gets closed, then one new instance can be created (but no more than N instances can run at any one time).
Thank you in advance.
a.
You can create a global semaphore that up to n process instances can enter. The n+1 th instance of your process will fail to enter the semaphore. Of course you should select a short timeout for the locking operation so you can present a meaningful feedback to the user.
For the semaphore stuff you can take a look at MSDN.
I'd use lock files. In your CMyApp::InitInstance() add:
CString Path;
// better get the path to the global app data or local user app data folder,
// depending on if you want to allow the three instances machine-wide or per user.
// Windows' file system virtualization will make GetModuleFileName() per user:
DWORD dw = GetModuleFileName(m_hInstance,
Path.GetBuffer(MAX_PATH), MAX_PATH);
Path.ReleaseBuffer();
// strip "exe" from filename and replace it with "lock"
Path = Path.Left(Path.GetLength()-3) + T("lock");
int i;
// better have the locking file in your class and do a clean Close on ExitInstance()!
CFile *pLockingFile = NULL;
for (i = 0; i < 3; i++) // restrict to three instances
{
CString Counter;
Counter.Format(T("%d"), i);
TRY
{
pLockingFile = new CFile(Path + Counter,
CFile::modeCreate|CFile::modeWrite|CFile::shareExclusive);
pLockingFile.Close();
break; // got an instance slot
}
CATCH( CFileException, e )
{
// maybe do something else here, if file open fails
}
END_CATCH
if (i >= 3)
return TRUE; // close instance, no slot available
}
Edit: To lock the software machine-wide, retrieve the common app folder using the following function instead of calling GetModuleFileName().
#pragma warning(disable: 4996) // no risk, no fun
BOOL GetCommonAppDataPath(char *path)
{
*path = '\0';
if (SHGetSpecialFolderPath(NULL, path, CSIDL_COMMON_APPDATA, TRUE))
{
strcat(path, T("\\MyApplication")); // usually found under C:\ProgramData\MyApplication
DWORD dwFileStat = GetFileAttributes(path);
if (dwFileStat == 0xffffffff) // no MyApplication directory yet?
CreateDirectory(path, NULL); // create it
dwFileStat = GetFileAttributes(path); // 2nd try, just to be sure
if (dwFileStat == 0xffffffff || !(dwFileStat & FILE_ATTRIBUTE_DIRECTORY))
return FALSE;
return TRUE;
}
return FALSE;
}
Note: This will only work from Vista on. If you have XP, writing to a global directory is an easy task, e.g. C:\Windows\Temp. I have put the function in a helper dll I only load if the OS is Vista or higher. Otherwise your software won't start because of unresolved references in system dlls.
the device driver I'm working on is implementing a virtual device. The logic
is as follows:
static struct net_device_ops virt_net_ops = {
.ndo_init = virt_net_init,
.ndo_open = virt_net_open,
.ndo_stop = virt_net_stop,
.ndo_do_ioctl = virt_net_ioctl,
.ndo_get_stats = virt_net_get_stats,
.ndo_start_xmit = virt_net_start_xmit,
};
...
struct net_device *dev;
struct my_dev *virt;
dev = alloc_netdev(..);
/* check for NULL */
virt = netdev_priv(dev);
dev->netdev_ops = &virt_net_ops;
SET_ETHTOOL_OPS(dev, &virt_ethtool_ops);
dev_net_set(dev, net);
virt->magic = MY_VIRT_DEV_MAGIC;
ret = register_netdev(dev);
if (ret) {
printk("register_netdev failed\n");
free_netdev(dev);
return ret;
}
...
What happens is that somewhere somehow the pointer net_device_ops in
'net_dev' gets corrupted, i.e.
1) create the device the first time (allocated net_dev, init the fields
including net_device_ops,which is
initialized with a static structure containing function pointers), register
the device with the kernel invoking register_netdev() - OK
2) attempt to create the device with the same name again, repeat the above
steps, call register_netdev() which will return negative and we
free_netdev(dev) and return error to the caller.
And between these two events the pointer to net_device_ops has changed,
although nowhere in the code it is done explicitly except the initialization
phase.
The kernel version is 2.6.31.8, platform MIPS. Communication channel between the user space and the kernel is implemented via netlink sockets.
Could anybody suggest what possibly can go wrong?
Appreciate any advices, thanks.
Mark
"The bug is somewhere else. "
The second device should not interact with the existing one. If you register_netdev with an existing name, nevertheless the ndo_init virtual function is called first before the condition is detected and -EEXIST is returned. Maybe your init function does something nasty involving some global variables. (For example, does the code assume there is one device, and stash a global pointer to it during initialization?)
We have *.exe application which is also out-process COM server.
The main thread is doing some network routine: it receives data packets and puts them into queue.
COM client, VBA for example, uses COM server and wants to use queue too. Despite the fact that they are in the same address space the question is:
How can we provide an opportunity for COM client to use the queue simultaneously with exe process.
There was an idea to use shared memory, but with no success
UPD:
I've tryed to use boost::interprocess.
Due to the same address space I've wanted just share object pointer.
std::vector<int> //just example of MyType
exe part:
main()
...
using namespace boost::interprocess;
struct shm_remove
{
shm_remove() { shared_memory_object::remove("SharedMemory"); }
~shm_remove(){ shared_memory_object::remove("SharedMemory"); }
} remover;
managed_shared_memory segment(open_or_create, "SharedMemory", 65536);
std::vector<int>** instance = segment.construct<std::vector<int>* >
("my_instance") //name of the object
(); //ctor first argument
*instance = new std::vector<int>();
(*instance)->push_back(1);
// initialize the COM library
::CoInitialize(NULL);`enter code here`
COM part:
HRESULT __stdcall CoMyCOMServer::Add(int *value)
{
cout << "Add()\n";
// this line goes out of debug, then VBA get error
managed_shared_memory segment(open_only, "SharedMemory");
std::vector<int>* *res = segment.find<std::vector<int>* > ("my_instance").first;
(*res)->push_back(*value);
return S_OK;
}
COM client(VBA) tells
Method "ADD" of object "IMyCOMServer" failed
Dim obj As IMyCOMServer
Set obj = CreateObject("MyCOMServer.object")
obj.Add (2)
UPD2:
I've just surrounded Com part with try{}catch{} and found out that the exception with the message "File not found"
Is there any way to postprocess a DLL and its .lib file to remove symbols that I do not want within them?
Background:
The DLL's code uses boost::serialization, which dllexports (many many) symbols. Apparently this is so as to cause the linker not to omit static objects that are unreferenced but have important side effects when initialized.
However, I'd very much prefer that there be no hint of boost within the DLL's exported symbols.
I reason that since the link step has completed that it would be safe to remove the mess in the symbol table caused by the library.
Hence, I am wondering if there exists some tool to accomplish this.
I don't know a tool that does this, but here is a piece of C++ code you can build that can change a DLL exported names. In this case, you can set the names you don't want to an empty string (the 0 character):
void RemoveUnwantedExports(PSTR ImageName)
{
LOADED_IMAGE image;
// load dll in memory for r/w access
// you'll need Imagehlp.h and Imagehlp.lib to compile successfully
if (MapAndLoad(ImageName, NULL, &image, TRUE, FALSE))
{
// get the export table
ULONG size;
PIMAGE_EXPORT_DIRECTORY exports = (PIMAGE_EXPORT_DIRECTORY)ImageDirectoryEntryToData(image.MappedAddress, FALSE, IMAGE_DIRECTORY_ENTRY_EXPORT, &size);
PIMAGE_SECTION_HEADER *pHeader = new PIMAGE_SECTION_HEADER();
// get the names address
PULONG names = (PULONG)ImageRvaToVa(image.FileHeader, image.MappedAddress, exports->AddressOfNames, pHeader);
for (ULONG i = 0; i < exports->NumberOfNames; i++)
{
// get a given name
PSTR name = (PSTR)ImageRvaToVa(image.FileHeader, image.MappedAddress, names[i] , pHeader);
// printf("%s\n", name); // debug info
if (IsUnwanted(name))
{
name[0] = 0; // set it to an empty string
}
}
UnMapAndLoad(&image); // commit & write
}
}
BOOL IsUnwanted(PSTR name)
{
// implement this
}
It's more some kind of obfuscation but removing names completely is more complex since it requires a full consistent rewrite of the exports section.
How do I get from a drive letter to a device instance ID?
My process starts with a device arrival message. I have been successful in getting the drive letter from the arrival message and in opening the dvd tray.
I have searched the various Setup API items; but I haven't found anything that gets me from a drive letter to a device instance ID.
A solution in C# or VB.NET would be ideal, but I'm willing to figure it out from any other language as long as I can see the API calls.
Thanks in advance...
You cannot do it directly.
The link is to use STORAGE_DEVICE_NUMBER. You can use DeviceIoControl with IOCTL_STORAGE_GET_DEVICE_NUMBER on your device name to populate this structure. Put this value to one side.
You then need to get device infomation on your system using SetupDiGetClassDevs setting the GUIDS as approriate, indicicating the drives your are insterested in. Then enumerate through the devices using SetupDiEnumDeviceInfo. Then enumerate the interfaces using SetupDiEnumDeviceInterfaces and finally get the information using SetupDiGetDeviceInterfaceDetail. In this structure returned you can get a DevicePath you can use to get the STORAGE_DEVICE_NUMBER as above. Match this with the STORAGE_DEVICE_NUMBER from your drive letter, and you have now linked a driver letter to your structure. Phew! Inside this structure is a DevInst.
i know it's late for you now but not for everybody ^^
I had the same need and this is main line of how I did it:
-You need a window to receive device arrival and removal (as you said)
-Then you create a DeviceNotificationFilter initiated to dbcc_devicetype = DBT_DEVTYP_DEVICEINTERFACE
-Then in the message loop of your window you look for VM_DEVICECHANGE
-When u receive it if wParam == DBT_DEVICEARRIVAL, use the lParam to check if it is a DBT_DEVTYPE_VOLUME (i was getting the letter and the type of the drive here) or a DBT_DEVTYPE_DEVICEINTERFACE ( there you can use your wellcasted lParam to get the InstanceId from the input structure).
When you connect a drive your receive DEVINTERFACE first then the other.
I only give the main line beacause i did this long time ago and i don't have the code here, and also I had found a lot of code pieces on the net (long time ago so there should be more now ^^^) maybe msdn give a full code example to do that now.
If you read this and need more informations, i'll reply or make a full documented answer if many need it.
Hope it will help some of you.
I know it's years later but I had to do this and searching brought me here and #DanDan 's answer worked. In order to save future people a lot of work, I thought I'd give back a little and present the technique a bit more explicitly. You'll still have to write a bit of code, but the part I found difficult is below as code:
As DanDan mentioned, the idea is to use CreateFile and DeviceIoControl to get the Windows STORAGE_DEVICE_NUMBER for the disk associated with a file path, and then use the Setup API to enumerate disk devices until we find one whose device instance equals the SDN.
First, here's a summary of how you get the STORAGE_DEVICE_NUMBER from the path (e.g. c:\\users\\bob);
Strip the path to the root (e.g down to C:) and prepend it with \\\\.\\ so you have \\\\.\\C:
Open that path up using CreateFileW with to get metadata
Use DeviceIoControl with IOCTL_VOLUME_GET_VOLUME_DISK_EXTENTS to get the extents
Get the DiskNumber member from the first extent returned.
Close the file
Open up \\\\.\\PhysicalDrive<n> where <n> is the that DiskNumber from the first extent
Use DeviceIoControl with code IOCTL_STORAGE_GET_DEVICE_NUMBER to get make it fill out a STORAGE_DEVICE_NUMBER struct as output
Use SetupDiGetClassDevs with arguments &GUID_DEVCLASS_DISKDRIVE and DICGF_PRESENT to get all disks on the system
In a loop, use SetupDiEnumDeviceInfo to get a SP_DEVINFO_DATA repeatedly (on the device list returned by step #8 above) and a call the function below to determine which one, if any, matches the STORAGE_DEVICE_NUMBER for the give path.
(This is edited to remove custom utility classes of mine right on the SO web page so I might have introduced errors/typos)
bool DoesDeviceInstanceEqualStorageDeviceNumber(
const std::string& devInstance,
STORAGE_DEVICE_NUMBER sdn)
{
// Open up this device instance, specifying that we want the *interfaces*.
// The interfaces are key key because examining them will let us get a
// string we can use the Win32 CreateFile function.
const auto hDevInfo = SetupDiGetClassDevsA(
nullptr,
devInstance.c_str(),
nullptr,
DIGCF_DEVICEINTERFACE | DIGCF_ALLCLASSES);
if (hDevInfo == INVALID_HANDLE_VALUE)
throws std::runtime_error("Unable to get disk devices");
DWORD dwSize = 0;
SP_DEVINFO_DATA did;
WCHAR buffer[4096];
did.cbSize = sizeof (did);
bool foundValidMatch = false;
int deviceNumber = 0;
// Iterate through all such devices, looking for one that has a storage device number that matches the given one.
while ( !foundValidMatch && SetupDiEnumDeviceInfo(hDevInfo, deviceNumber, &did))
{
deviceNumber++;
DEVPROPTYPE devPropType;
// We'll only bother comparing this one if it is fixed. Determine that.
const auto getPropResult = SetupDiGetDevicePropertyW (
hDevInfo,
&did,
&DEVPKEY_Device_RemovalPolicy, // Ask for the "removal policy"
&devPropType,
(BYTE*)buffer,
sizeof(buffer),
&dwSize,
0);
if (!getPropResult)
{
std::cerr << "Unable to to get removal policy for disk device: " << ::GetLastError() << std::endl;
continue;
}
/* This bit *would* skip removable disks, you wanted...
else if (buffer[0] != 1)
{
std::cerr << "Skipping removable disk device " << devInstance << std::endl;
continue;
}
*/
// OK this is a fixed disk so it might be the one we'll compare against
// 1. Get the very first disk interface from this particular disk device
// 2. Open a file on it
// 3. Query the resulting file for its device number.
// 4. Compare the device number to the one we determined above
// 5. If it matches ours, then we succeed. If not, continue
SP_DEVICE_INTERFACE_DATA devIntData;
devIntData.cbSize = sizeof(SP_DEVICE_INTERFACE_DATA);
// Get the disk interfaces
const auto result = SetupDiEnumDeviceInterfaces(
hDevInfo,
&did, //&did,
&GUID_DEVINTERFACE_DISK, // Get Disk Device Interface (from winioctl.h)
0, // We only need the very FIRST one. I think...
&devIntData);
if (!result)
continue;
DWORD dwRequiredSize = 0;
// Want to get the detail but don't yet know how much space we'll need
// Do a dummy call to find out
SetupDiGetDeviceInterfaceDetail(
hDevInfo,
&devIntData,
nullptr,
0,
&dwRequiredSize,
nullptr);
if (ERROR_INSUFFICIENT_BUFFER != ::GetLastError())
{
std::cerr << "Unable to get device interface Detail: " << ::GetLastError() << std::endl;;
}
else
{
// Get the detail data so we can get the device path and open a file.
std::vector<TCHAR> buf(dwRequiredSize);
auto pDidd = reinterpret_cast<PSP_DEVICE_INTERFACE_DETAIL_DATA>(buf.data());
// WARNING: HARD CODED HACK
// ------------------------
// https://stackoverflow.com/questions/10405193/vb-net-hid-setupdigetdeviceinterfacedetail-getlasterror-shows-1784-error-inv
//
// Don't ask. Just do what they tell you.
// -----------------------------------------------------------------
#ifdef BUILD_64
pDidd->cbSize = 8;
#else
pDidd->cbSize = 6;
#endif
// -----------------------------------------------------------------
if (!SetupDiGetDeviceInterfaceDetail(
hDevInfo,
&devIntData,
pDidd,
dwRequiredSize,
&dwRequiredSize,
nullptr))
{
std::cerr << "Cannot get interface detail: " << ::GetLastError());
}
else
{
// FINALLY: We now have a DevicePath that we can use to open up
// in a Win32 CreateFile() call. That will let us get the
// STORAGE_DEVICE_NUMBER and compare it to the one we were given.
const auto hFile = ::CreateFileW(pDidd->DevicePath, 0, FILE_SHARE_READ, nullptr, OPEN_EXISTING, 0, NULL);
if (INVALID_HANDLE_VALUE != hFile)
{
std::cerr << "Unable to open logical volume: " + devicePath << std::endl;
continue;
}
STORAGE_DEVICE_NUMBER sdnTest;
ZeroMemory(&sdnTest, sizeof(STORAGE_DEVICE_NUMBER));
if (0 == DeviceIoControl(
hDevInfo
IOCTL_STORAGE_GET_DEVICE_NUMBER,
nullptr, // output only so not needed
0, // output only so not needed
&sdnTest,
sizeof(STORAGE_DEVICE_NUMBER),
nullptr,
nullptr))
{
std::cerr << "Unable to determine storage device number: " << ::GetLastError() << std::endl;);
}
else
{
// All this for a one-line test...
foundValidMatch = sdnTest.DeviceNumber == sdn.DeviceNumber;
}
}
}
}
SetupDiDestroyDeviceInfoList(hDevInfo);
return foundValidMatch;
}
I hope this saves someone a headache