In C#, I am using an external dll, using loadLibrary, like this:
public class Utilities
[DllImport("kernel32", CharSet= CharSet.Auto, SetLastError=true)]
private static extern IntPtr LoadLibrary(string librayName);
[DllImport("kernel32", CharSet= CharSet.Auto, SetLastError=true)]
private static extern IntPtr GetProcAddress(intPtr hwnd, string procedureName);
public static LoadAssembliesAndMethods() {
string mainPath = AppDomain.CurrentDomain.BaseDirectory;
string path = Path.Combine(mainPath, "MyAssembly.dll");
IntPtr ptr = LoadLibrary(path);
// What to do next in order to get all the list of functions/methods/class in the library and use them?
}
The dll has no signature of Assembly (it's a 3rd party), so I cannot do
Assebly.LoadFile(path);
I need to get all of the functions/methods/class of the dll, and use some of them, using C#.
How can I do that.
If you want to list all methods inside a unmanaged dll this link help you:
C# get the list of unmanaged C dll exports
Update:
IntPtr funcaddr = GetProcAddress(Handle,functionName);
YourFunctionDelegate function =
Marshal.GetDelegateForFunctionPointer(funcaddr,typeof(YourFunctionDelegate ))
as YourFunctionDelegate ;
function.Invoke(pass here your parameters);
you need to create delegates at coding or using DynamicModules for creating delegates at runtime
There is no common way to get the export list of a unmanaged library programatically.
See Is there a way to find all the functions exposed by a dll for more info
Related
I am using the Hardware ID Extractor library (written in Delphi) from http://www.soft.tahionic.com/download-hdd_id/index.html with the purpose of generating unique system fingerprints.
The library is really good and unlike anything else I have seen on the market, but the main issue with it is that it's unstable when running with .NET applications, meaning that it sometimes works, other times it works for a few function calls then the main application crashes, or most of the time the application instantly crashes when a dll function is being called.
As the developer of the library pointed out (in the last support e-mail that I have received), the fault is with ntdll.dll, as I have seen that for myself:
Following is a link to a demo project I have created with the purpose of testing the dll functions (so to make sure that nothing else interferes, the demo app does that and only that- it calls the dll functions).
http://www.mediafire.com/download/1jws7zh9218v88a/HardwareIdExtractDllTest.zip
The archive contains the Visual Studio 2013 project with source code and a compiled demo application which looks like this:
The list of functions contained by the dll can be found here:
http://www.soft.tahionic.com/download-hdd_id/hardware%20id%20programming%20source%20code/exported%20functions%20for%20non-Delphi.html
If anyone has the knowledge and is willing to test the demo project/application to make tests or personal opinions in regard to the issue, and then share a possible solution with me, I would be grateful.
Please let me know if there's anything I can do to further assist in solving this issue if you think there's anything that can be done about it.
EDIT: This is how I am declaring the dll functions
[DllImport("HardwareIDExtractorC.dll")]
private static extern bool EnterKey(int key);
[DllImport("HardwareIDExtractorC.dll")]
private static extern bool IsCPUIDAvailable();
[DllImport("HardwareIDExtractorC.dll")]
private static extern int GetCPUCount();
[DllImport("HardwareIDExtractorC.dll")]
private static extern byte CoreNumber2CoreMask(byte cpuCore);
[DllImport("HardwareIDExtractorC.dll", CallingConvention = CallingConvention.StdCall, CharSet = CharSet.Ansi, EntryPoint = "GetCPUID")]
[return: MarshalAs(UnmanagedType.LPStr)]
private static extern string GetCPUID(byte cpuCore);
[DllImport("HardwareIDExtractorC.dll", CallingConvention = CallingConvention.StdCall, CharSet = CharSet.Ansi, EntryPoint = "GetCpuIdNow")]
[return: MarshalAs(UnmanagedType.LPStr)]
private static extern string GetCpuIdNow();
[DllImport("HardwareIDExtractorC.dll", CallingConvention = CallingConvention.StdCall, CharSet = CharSet.Ansi, EntryPoint = "GetIDESerialNumber")]
[return: MarshalAs(UnmanagedType.LPStr)]
private static extern string GetIDESerialNumber(byte driveNumber);
The functions that fail are the ones that return string. Such a p/invoke marshals the return value as a pointer to null terminated character array, and then calls CoTaskMemFree on the raw pointer returned by the unmanaged code.
With probability close to 1 that string was not allocated on the COM heap and so the error is likely in the C# p/invoke declarations. That an access violation then arises in ntdll is quite plausible.
So, to make progress you need to fix the p/invoke calls. I cannot tell you how to do so because you have not shown the unmanaged function declarations. Or, more importantly, how the memory is allocated.
There are some clues at the documentation
procedure ReleaseMemory (P: PAnsiChar); stdcall;
I think this tells us that the strings returned by the DLL must be deallocated by the DLL, by calling this function. Presumably because they were allocated by the DLL's heap allocator.
So, use IntPtr for the return type of the functions that return text. Call Marshal.PtrToStringAnsi to convert to a C# string. And then pass the pointer to ReleaseMemory.
For example:
[DllImport(DllPath, CallingConvention = CallingConvention.StdCall)]
private static extern IntPtr GetCPUID(ushort CoreMask);
[DllImport(DllPath, CallingConvention = CallingConvention.StdCall)]
private static extern void ReleaseMemory(IntPtr P);
....
IntPtr ptr = GetCPUID(CoreMask);
string cpuid = Marshal.PtrToStringAnsi(ptr);
ReleaseMemory(ptr);
I'm writing a super-simple ultra-lite weight .Net wrapper for the LibVLC media library since the only things I need access to are the ability to play, pause and stop media files. I've posted a couple of questions on this and gotten some answers but unfortunately I'm just left with more questions.
We'll start from the top and work down.
The documentation first states I have to initialize VLC with a call to the function with this specification:
libvlc_instance_t* libvlc_new (int argc, const char *const *argv)
for which I have the defined the following method:
[DllImport("libvlc", EntryPoint = "libvlc_new",
CallingConvention = CallingConvention.Cdecl)]
public static extern IntPtr NewCore(int argc, IntPtr argv);
And I'm calling the function like this:
private IntPtr Instance;
this.Instance = DGLibVLC.NewCore(0, IntPtr.Zero);
I have tried it several different ways. Initially I did not know about the CallingConvention which was leading to an unbalanced stack which brought me here in the first place. That issue was resolved and the method has gone through several iterations, none of which have proved successful, by which I mean IntPtr is always 0 after the method call. I've tried it like it is above, with the second argument being String[] argc, [MarshalAs(UnmanagedType.LPArray, ArraySubType = UnmanagedType.LPStr)] string[],
I've tried having it return to a Long (which actually resulted in the Long having a value in it), but nothing so far has worked correctly.
Does anyone know the correct way to call this function from the LibVLC DLL Library?
EDIT: On a suggestion I tried calling the error message function of the library:
Specification:
const char* libvlc_errmsg (void)
Implementation:
[DllImport("libvlc", EntryPoint = "libvlc_errmsg",
CallingConvention = CallingConvention.Cdcel)]
public static extern string GetLastError();
Call:
Console.WriteLine(DGLibVLC.GetLastError());
Result:
Null
The documentation states it will return Null if there is no error. This must indicate that the initial function call NewCore was working correctly but something is still going wrong somehow.
To be cover all bases I checked that the DLLs match the documentation, they do. 2.0.6.0. The documentation I am referencing is here.
EDIT: I can confirm there is no error. When using an initialized to zero long variable to store the result of NewCore I can see it returning something. What I am doing wrong here is where I am trying to store the pointer being returned by the unmanaged function that returns the pointer to the object. How do I store the pointer to the opaque structure reference being passed back?
It doesn't have anything to do with the way you call the function. You cannot get anywhere when you get IntPtr.Zero back from libvlc_new(). It means "there was an error". You'll need to focus on error reporting first, call libvlc_errmsg() to try to get a description for the problem.
So after much looking around and asking questions I've come full circle.
I looked deeply into LibVLC.Net and found how they were importing the DLL functions and adapted what they did to my own wrapper and it worked.
To summarize:
There are some Win32 API functions declared in the code at the start:
[DllImport("kernel32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
private static extern bool SetDllDirectory(string lpPathName);
[DllImport("kernel32", SetLastError = true)]
private static extern IntPtr LoadLibrary(string lpFileName);
[DllImport("kernel32", CharSet = CharSet.Ansi, ExactSpelling = true, SetLastError = true)]
private static extern IntPtr GetProcAddress(IntPtr hModule, string procName);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool FreeLibrary(IntPtr hModule);
that handle providing a handle to a dll and setting a directory search path.
I don't know exactly what it all means but when you initialize the LibVLC.Net library (the primary object) it loads pretty much EVERY function like so:
m_libvlc_media_player_new = (libvlc_media_player_new_signature)LoadDelegate<libvlc_media_player_new_signature>("libvlc_media_player_new");
That delegate is defined here like so:
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
private delegate IntPtr libvlc_media_player_new_signature(IntPtr p_instance);
//==========================================================================
private readonly libvlc_media_player_new_signature m_libvlc_media_player_new;
//==========================================================================
public IntPtr libvlc_media_player_new(IntPtr p_instance)
{
VerifyAccess();
return m_libvlc_media_player_new(p_instance);
}
And it has a public function that calls the delegate once defined.
I simply stripped down the function that defines the library instance and imported only the functionality I needed.
Thanks very much to everyone who was so patient in helping me along. I likely wouldn't have been able to come to a solution without your help.
EDIT: Okay so it wasn't that. It was the location of the LibVLC Plugin Directory. So it was something stupid -.-;
I will completely describe you my problem and process. I was making an editor for an other's game and I have one wrapper DLL written in C language which I am communicating with.
At first I had list of methods with DllImport calling functions from the DLL. First method was CSharp_new_CEditorInterface which returned an IntPtr. Then CSharp_CEditorInterface_CreateApp which toke ulong handle to window control where it will draw graphics. At the end I should call CSharp_CEditorInterface_CloseApp and CSharp_delete_CEditorInterface. These methods take a HandleRef with pointer returned from CSharp_new_CEditorInterface.
However, I needed to call creating and deleting methods multiple times and when calling CSharp_CEditorInterface_CreateApp for the second time, it threw System.AccessViolationException. So I decided to load and unload DLL dynamically with LoadLibrary and FreeLibrary. I wrote an application that with reflection browsed all p/invoke methods and generated code consisting of delegates, readonly fields and GetProcAddress-es. However, as I found out, the entry points were only partial. CSharp_new_CEditorInterface was _CSharp_new_CEditorInterface#0. With my DLL export viewer, I saved all complete function names and then searched within. In constructor, I call LoadLibrary and appropriate function loads. In Dispose, there was FreeLibrary.
This solution worked fine, functions were called OK, until I discovered that some functions which return string are throwing AccessViolationException. They work fine when using DllImport method. I have also discovered that when calling ANY function from static class, thus loading another module, calling problematic functions is now OK and they return appropriate values. However, after unloading DLL dynamically and reloading, it does not work again and guess which exception is thrown.
Now which function I call and in what order:
--When initializing--
LoadLibrary(string) (winapi)
--bunch of GetProcAddress, Marshal.GetDelegateForFunctionPointer--
new_CEditorInterface() (from DLL)
CreateApp(HandleRef, ulong) (from DLL)
--When closing in Dispose--
CloseApp(HandleRef) (from DLL)
delete_CEditorInterface(HandleRef) (from DLL)
FreeLibrary(IntPtr) (winapi)
I should note that the DLL was not created to be loaded more than one at a time.
Can somebody help me, please?
Try this I hope that this helps you
[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr LoadLibrary(string libname);
[DllImport("kernel32.dll", CharSet = CharSet.Auto)]
private static extern bool FreeLibrary(IntPtr hModule);
//Load
IntPtr Handle = LoadLibrary(fileName);
if (Handle == IntPtr.Zero)
{
int errorCode = Marshal.GetLastWin32Error();
throw new Exception(string.Format("Failed to load library (ErrorCode: {0})",errorCode));
}
//Free
if(Handle != IntPtr.Zero)
FreeLibrary(Handle);
If you want to call functions first you must create delegeate that matches this function
and then use WinApi GetProcAddress
[DllImport("kernel32.dll", CharSet = CharSet.Ansi)]
private static extern IntPtr GetProcAddress(IntPtr hModule, string lpProcName);
IntPtr funcaddr = GetProcAddress(Handle,functionName);
YourFunctionDelegate function = Marshal.GetDelegateForFunctionPointer(funcaddr,typeof(YourFunctionDelegate )) as YourFunctionDelegate ;
function.Invoke(pass here your parameters);
HI all,
I would like to call from my C# code, unamanaged library functions like presented below. There are two options and the both works. In this moment "Beep" function is simple and have no input/output parameters, pointers, references... I am wondering in more complex cases what would be adventages and disadvantage of both approches ?
Thanks,
Milan.
[DllImport("kernel32.dll")]
public static extern bool Beep(uint iFreq, uint iDuration);
public void TestBeep()
{
Beep(300, 3000);
}
internal delegate bool DelegBeep(uint iFreq, uint iDuration);
[DllImport("kernel32.dll")]
internal static extern IntPtr LoadLibrary(String dllname);
[DllImport("kernel32.dll")]
internal static extern IntPtr GetProcAddress(IntPtr hModule, String procName);
public void BeepIt()
{
IntPtr kernel32 = LoadLibrary("Kernel32.dll");
IntPtr procBeep = GetProcAddress(kernel32, "Beep");
DelegBeep delegBeep = Marshal.GetDelegateForFunctionPointer(procBeep, typeof(DelegBeep)) as DelegBeep;
delegBeep(50, 1000);//Hz,ms
}
Your second one is much more complicated than the first but achieves the same thing in this case.
If the name of the DLL and the name of the function are known at compile time, then stick with the first approach. If you don't know the name of the DLL and/or function until run time then the LoadLibary/GetProcAddress approach is your only option.
The P/Invoke marshaller finds an entrypoint in a DLL by using LoadLibrary() and GetProcAddress(). And knows how to convert a C# declaration to the equivalent of a delegate declaration.
Doing this yourself has no advantage beyond maybe a wee bit of efficiency. Which you'd better measure, it is no slamdunk.
I am developing a Windows Mobile application using WM6 SDK. The application is a Managed code (using C#) & I would like to know the steps to be taken in order to call native functions.
Thanks for the help,
Abdel Olakara
http://www.pinvoke.net/
That should do it.
You need to first declare the native APIs as static extern using DLLImport and then use them like normal methods. Example:
[DllImport("user32.dll", ExactSpelling = true)]
internal static extern IntPtr SetTimer(IntPtr hWnd, IntPtr nIDEvent, int uElapse, IntPtr lpTimerFunc);