GetThreadDescription() -> What is the proper declaration in C#? - c#

What is the proper method declaration / DllImport for GetThreadDescription() for C#?
Here is what I have thus far:
[DllImport("kernel32.dll", SetLastError = true)]
public static extern UIntPtr GetThreadDescription(UIntPtr hThread, [Out, MarshalAs(UnmanagedType.LPWStr)] out string ppszThreadDescription);
[DllImport("kernel32.dll")]
static extern UIntPtr OpenThread(ThreadAccess dwDesiredAccess, bool bInheritHandle, uint dwThreadId);
public static void Suspend(this Process process)
{
foreach (ProcessThread thread in process.Threads)
{
var pOpenThread = OpenThread(ThreadAccess.SUSPEND_RESUME, false, (uint)thread.Id);
if (pOpenThread == UIntPtr.Zero)
{
break;
}
string threaddescription = string.Empty;
GetThreadDescription(pOpenThread, out threaddescription);
System.Diagnostics.Debug.WriteLine("Thread Description: " + threaddescription);
SuspendThread(pOpenThread);
}
}
The string it returns is empty. Changing the MarshalAs to different types of strings has, thus far, yielded nothing. I checked pinvoke.net, and could not find it.

Related

Error 6 when injecting DLL using C#

when I try to inject a DLL with C# into a java process (Minecraft specifically) I get an error "ERROR 6", I've been googling this error but couldnt find a solution.
The program is run in administrator mode, and it isnt trying to load from an admin path.
My code:
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Text;
namespace Launcher
{
internal class InjectionUtils
{
public struct CTX_PROCS
{
public Process[] procs;
}
private const int PROCESS_CREATE_THREAD = 2;
private const int PROCESS_QUERY_INFORMATION = 1024;
private const int PROCESS_VM_OPERATION = 8;
private const int PROCESS_VM_WRITE = 32;
private const int PROCESS_VM_READ = 16;
private const uint MEM_COMMIT = 4096u;
private const uint MEM_RESERVE = 8192u;
private const uint PAGE_READWRITE = 4u;
[DllImport("kernel32.dll")]
public static extern IntPtr OpenProcess(int dwDesiredAccess, bool bInheritHandle, int dwProcessId);
[DllImport("kernel32.dll", CharSet = CharSet.Auto)]
public static extern IntPtr GetModuleHandle(string lpModuleName);
[DllImport("kernel32", CharSet = CharSet.Ansi, ExactSpelling = true, SetLastError = true)]
private static extern IntPtr GetProcAddress(IntPtr hModule, string procName);
[DllImport("kernel32.dll", ExactSpelling = true, SetLastError = true)]
private static extern IntPtr VirtualAllocEx(IntPtr hProcess, IntPtr lpAddress, uint dwSize, uint flAllocationType, uint flProtect);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool WriteProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, byte[] lpBuffer, uint nSize, out UIntPtr lpNumberOfBytesWritten);
[DllImport("kernel32.dll")]
private static extern IntPtr CreateRemoteThread(IntPtr hProcess, IntPtr lpThreadAttributes, uint dwStackSize, IntPtr lpStartAddress, IntPtr lpParameter, uint dwCreationFlags, IntPtr lpThreadId);
[DllImport("user32.dll", CharSet = CharSet.Auto)]
private static extern int MessageBox(IntPtr hWnd, string text, string caption, uint option);
[DllImport("kernel32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
private static extern bool CloseHandle(IntPtr hObject);
[DllImport("kernel32.dll")]
private static extern uint GetLastError();
private void MBox(string text)
{
InjectionUtils.MessageBox(IntPtr.Zero, text, "", 0u);
}
public void DoInjection(string dllPath)
{
InjectionUtils.CTX_PROCS cTX_PROCS = this.FindProcessByNameAndTitle("javaw", "Minecraft 1.7");
this.InjectDynamicLib(dllPath, cTX_PROCS.procs[0].Id);
}
public InjectionUtils.CTX_PROCS FindProcessByNameAndTitle(string processName, string title)
{
InjectionUtils.CTX_PROCS result = default(InjectionUtils.CTX_PROCS);
List<Process> list = new List<Process>();
Process[] processes = Process.GetProcesses();
for (int i = 0; i < processes.Length; i++)
{
Process process = processes[i];
if (process.ProcessName.Equals(processName) && process.MainWindowTitle.Contains(title))
{
list.Add(process);
}
}
result.procs = list.ToArray();
return result;
}
public void eject()
{
}
private bool InjectDynamicLib(string dllPath, int pId)
{
bool result = false;
IntPtr intPtr = InjectionUtils.OpenProcess(1082, false, pId);
uint num = (uint)((dllPath.Length + 1) * Marshal.SizeOf(typeof(char)));
if (intPtr != IntPtr.Zero)
{
IntPtr procAddress = InjectionUtils.GetProcAddress(InjectionUtils.GetModuleHandle("kernel32.dll"), "LoadLibraryA");
IntPtr intPtr2 = InjectionUtils.VirtualAllocEx(intPtr, IntPtr.Zero, num, 12288u, 4u);
UIntPtr uIntPtr;
// Write path of dll to remote process
if (InjectionUtils.WriteProcessMemory(intPtr, intPtr2, Encoding.Default.GetBytes(dllPath), num, out uIntPtr))
{
InjectionUtils.CloseHandle(InjectionUtils.CreateRemoteThread(intPtr, IntPtr.Zero, 0u, procAddress, intPtr2, 0u, IntPtr.Zero));
result = true;
}
InjectionUtils.CloseHandle(intPtr);
}
if (InjectionUtils.GetLastError() != 0u)
{
this.MBox("ERROR " + InjectionUtils.GetLastError());
}
return result;
}
If anyone could help I would appreciate it dearly :)
Thanks in advance :D
From MSDN Error Code List:
ERROR_INVALID_HANDLE
0x6
Before you call GetLastError() you call CloseHandle() twice, once on the thread handle and on the process handle.
To find the problem just check the returns from OpenProcess() and CreateRemoteThread() and compare against the info you find in the functions documentation on MSDN.
For a simple no frills C# injector, this is the code I like to use which includes some error checking and uses the managed Process::Dispose() method instead of calling the native CloseHandle() at least on the process handle:
public static bool InjectDLL(string dllpath, string procname)
{
Process[] procs = Process.GetProcessesByName(Path.GetFileNameWithoutExtension(procname));
if (procs.Length == 0)
{
return false;
}
Process proc = procs[0];
if (proc.Handle != IntPtr.Zero)
{
IntPtr loc = VirtualAllocEx(proc.Handle, IntPtr.Zero, MAX_PATH, AllocationType.Commit | AllocationType.Reserve,
MemoryProtection.ReadWrite);
if (loc.Equals(0))
{
return false;
}
IntPtr bytesRead = IntPtr.Zero;
bool result = WriteProcessMemory(proc.Handle, loc, dllpath.ToCharArray(), dllpath.Length, out bytesRead);
if (!result || bytesRead.Equals(0))
{
return false;
}
IntPtr loadlibAddy = GetProcAddress(GetModuleHandle("kernel32.dll"), "LoadLibraryA");
IntPtr hThread = CreateRemoteThread(proc.Handle, IntPtr.Zero, 0, loadlibAddy, loc, 0, out _);
if (!hThread.Equals(0))
{
CloseHandle(hThread);
}
else return false;
}
else return false;
//this will CloseHandle automatically using the managed method
proc.Dispose();
return true;
}
Make sure to run as admin and pinvoke any missing definitions.

Getting Symbols from debugged process MainModule

I started writing a debugger in C#, to debug any process on my operating system. For now, it only can handle breakpoints (HW, SW, and Memory), but now I wanted to show the opcode of the process.
My first attempt was with nidsasm (NASM), but this is not suitable, because after startup a.Net Application assembler instructions are different from ndisasm (tested with CheatEngine).
So I searched a while and found some methods from the dbghelp.dll which can be called to list all loaded modules and symbols (plus the base address). Ok, my attempt is, to disassemble all modules separately with SharpDisasm.
I use ProcessModuleCollection modules = ProcessData.Instance.MPMR.ReadProcess.Modules; to get all loaded modules of the process. This works perfectly.
Now I tried to load the symbols of the MainModule, but at this point, I stuck with the implementation. I implemented the SymEnumSymbols Function with p/Invoke and other necessary functions like SymInitialize.
When I call it with a BaseAddress of for example the "User32.dll", all symbols are printed perfectly, but for the MainModule, I didn't get any symbols.
This is a screenshot from CheatEngine:
Symbols gained from Cheat Engine
As you can see, there are symbols like "Form1_Load", which I don't get with my implementation.
This is the necessary code sample:
if (!DebugApi.SymInitialize(ProcessData.Instance.MPMR.M_hProcess, null, false))
{
var err = Marshal.GetLastWin32Error();
//throw new Exception("GetMemoryInfo failed : GetLastError() : " + new Win32Exception(err).Message);
Console.WriteLine("GetMemoryInfo failed : GetLastError() : " + new Win32Exception(err).Message);
return;
}
if (!DebugApi.SymEnumSymbols(ProcessData.Instance.MPMR.M_hProcess, (ulong)ProcessData.Instance.MPMR.ReadProcess.MainModule.BaseAddress, "!", DebugApi.EnumSyms, IntPtr.Zero))
{
var err = Marshal.GetLastWin32Error();
//throw new Exception("GetMemoryInfo failed : GetLastError() : " + new Win32Exception(err).Message);
Console.WriteLine("GetMemoryInfo failed : GetLastError() : " + new Win32Exception(err).Message);
return;
}
DebugApi.SymCleanup(ProcessData.Instance.MPMR.M_hProcess);
And my DebugApi, with all necessary p/Invoke functions.
public class DebugApi
{
[DllImport("dbghelp.dll", SetLastError = true, CharSet = CharSet.Unicode)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool SymInitialize(IntPtr hProcess, string UserSearchPath, [MarshalAs(UnmanagedType.Bool)]bool fInvadeProcess);
[DllImport("dbghelp.dll", SetLastError = true, CharSet = CharSet.Unicode)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool SymCleanup(IntPtr hProcess);
[DllImport("dbghelp.dll", SetLastError = true, CharSet = CharSet.Unicode)]
public static extern ulong SymLoadModuleEx(IntPtr hProcess, IntPtr hFile, string ImageName, string ModuleName, long BaseOfDll, int DllSize, IntPtr Data, int Flags);
[DllImport("dbghelp.dll", SetLastError = true, CharSet = CharSet.Unicode)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool SymEnumSymbols(IntPtr hProcess, ulong BaseOfDll, string Mask, PSYM_ENUMERATESYMBOLS_CALLBACK EnumSymbolsCallback, IntPtr UserContext);
public delegate bool PSYM_ENUMERATESYMBOLS_CALLBACK(ref SYMBOL_INFO pSymInfo, uint SymbolSize, IntPtr UserContext);
public static bool EnumSyms(ref SYMBOL_INFO pSymInfo, uint SymbolSize, IntPtr UserContext)
{
Console.Out.WriteLine("Name: " + pSymInfo.Name);
return true;
}
[Flags]
public enum SymFlag : uint
{
VALUEPRESENT = 0x00000001,
REGISTER = 0x00000008,
REGREL = 0x00000010,
FRAMEREL = 0x00000020,
PARAMETER = 0x00000040,
LOCAL = 0x00000080,
CONSTANT = 0x00000100,
EXPORT = 0x00000200,
FORWARDER = 0x00000400,
FUNCTION = 0x00000800,
VIRTUAL = 0x00001000,
THUNK = 0x00002000,
TLSREL = 0x00004000,
}
[Flags]
public enum SymTagEnum : uint
{
Null,
Exe,
Compiland,
CompilandDetails,
CompilandEnv,
Function,
Block,
Data,
Annotation,
Label,
PublicSymbol,
UDT,
Enum,
FunctionType,
PointerType,
ArrayType,
BaseType,
Typedef,
BaseClass,
Friend,
FunctionArgType,
FuncDebugStart,
FuncDebugEnd,
UsingNamespace,
VTableShape,
VTable,
Custom,
Thunk,
CustomType,
ManagedType,
Dimension
};
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public struct SYMBOL_INFO
{
public uint SizeOfStruct;
public uint TypeIndex;
public ulong Reserved1;
public ulong Reserved2;
public uint Reserved3;
public uint Size;
public ulong ModBase;
public SymFlag Flags;
public ulong Value;
public ulong Address;
public uint Register;
public uint Scope;
public SymTagEnum Tag;
public int NameLen;
public int MaxNameLen;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 1024)]
public string Name;
}
}
My Functions should be ok, because it works with other Modules (loaded dll's for example). Maybe I don't understand the concept of symbols of a .Net Executable or missing something.
can it be that you are looking for System.Diagnostics.SymbolStore.ISymbolScope.
Have a look at the class SymbolAccess, you can use it to gain access to ISymbolScope.GetLocals() that returns ISymbolVariable[] and GetChildren() again returning in this time an array called ISymbolVariable[]
Now another interesting set of reference code samples is the Debugger extension lets you "snif" the values as shown here

FindNextFile ERROR_INVALID_NAME

I'm trying to use the WINAPI functions FindFirstFile and FindNextFile.
However, I'm experiencing some issues.
When I first call the function FindFirstFile it works fine. I've got a valid handler and the first folder/file name is properly populated inside the WIN32_FIND_DATA structure. No error is found with GetLastError.
Then, I call FindNextFile which returns true as there are more folders in the directory I'm scanning. But I can't retrieve the next folder/file name and GetLastError returns 123 (0x7B) ERROR_INVALID_NAME.
I'm a little confused as it says in the official documentation that if an error occurs it should return 0.
https://msdn.microsoft.com/en-us/library/windows/desktop/aa364428(v=vs.85).aspx
Return value
If the function succeeds, the return value is nonzero and the lpFindFileData parameter contains information about the next file or directory found.
If the function fails, the return value is zero and the contents of lpFindFileData are indeterminate. To get extended error information, call the GetLastError function.
If the function fails because no more matching files can be found, the GetLastError function returns ERROR_NO_MORE_FILES.
I'm using .NET 4.5.1 and Visual Studio 2013 on Windows 7 x64.
Here is a sample code.
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct WIN32_FIND_DATA
{
public uint dwFileAttributes;
public System.Runtime.InteropServices.ComTypes.FILETIME ftCreationTime;
public System.Runtime.InteropServices.ComTypes.FILETIME ftLastAccessTime;
public System.Runtime.InteropServices.ComTypes.FILETIME ftLastWriteTime;
public uint nFileSizeHigh;
public uint nFileSizeLow;
public uint dwReserved0;
public uint dwReserved1;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
public string cFileName;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 14)]
public string cAlternateFileName;
}
...
[DllImport("Kernel32.dll", EntryPoint = "FindFirstFile", SetLastError = true)]
public static extern IntPtr FindFirstFile(string lpFileName, ref WIN32_FIND_DATA lpFindFileData);
[return: MarshalAs(UnmanagedType.Bool)]
[DllImport("Kernel32.dll", EntryPoint = "FindFirstFile", SetLastError = true)]
public static extern bool FindNextFile(IntPtr hFindFile, ref WIN32_FIND_DATA lpFindFileData);
[return: MarshalAs(UnmanagedType.Bool)]
[DllImport("Kernel32.dll", EntryPoint = "FindClose", SetLastError = true)]
public static extern bool FindClose(IntPtr hFindFile);
...
public static void Test()
{
WIN32_FIND_DATA metaDataFile = new WIN32_FIND_DATA();
IntPtr nextHandle = FileScanner.FindFirstFile("C:\\*", ref metaDataFile);
Console.WriteLine(Marshal.GetLastWin32Error()); // This equals 0x0 ERROR_SUCCESS
Console.WriteLine(metaDataFile.cFileName); // This equals $Recycle.Bin
/* Check invalid handler */
if (nextHandle != new IntPtr(-1L))
{
bool moreFiles = true;
while (moreFiles)
{
moreFiles = FileScanner.FindNextFile(nextHandle, ref metaDataFile);
Console.WriteLine(Marshal.GetLastWin32Error()); // This equals 0x7B ERROR_INVALID_NAME
Console.WriteLine(metaDataFile.cFileName); // This equals $Recycle.Bin and this value never change.
}
FindClose(nextHandle);
}
}
For some reason, moreFiles is always true and GetLastError returns ERROR_INVALID_NAME ...
If you need any details please ask me.
Any help would really be appreciated !
Only call Marshal.GetLastWin32Error is the API call reports failure. In the case of FindNextFile it does so by returning false. You are checking the value returned by Marshal.GetLastWin32Error indiscriminately.
The documentation makes this clear when it tells you how the functions indicate failure. You even linked the text. But you said:
I'm a little confused as it says in the official documentation that if an error occurs it should return 0.
That's right. So check the return value against 0. In the case of a BOOL marshalled as C# bool, that means that the function returns false if it fails. But you simply ignored the return value and tested the value returned by Marshal.GetLastWin32Error(), something altogether different.
The code should be more like this:
public static void Test()
{
WIN32_FIND_DATA fd = new WIN32_FIND_DATA();
IntPtr findHandle = FileScanner.FindFirstFile("C:\\*", ref fd);
if (findHandle == INVALID_HANDLE_VALUE)
throw new Win32Exception();
do
{
Console.WriteLine(fd.cFileName);
} while (FileScanner.FindNextFile(findHandle, ref fd));
// you might check that Marshal.GetLastWin32Error() returns ERROR_NO_MORE_FILES
// at this point, otherwise the enumeration failed abnormally
if (!FindClose(findHandle))
throw new Win32Exception();
}
Your other problem, and it's what hurting you most, is your p/invoke declarations. Look closely at this one:
[return: MarshalAs(UnmanagedType.Bool)]
[DllImport("Kernel32.dll", EntryPoint = "FindFirstFile", SetLastError = true)]
public static extern bool FindNextFile(IntPtr hFindFile,
ref WIN32_FIND_DATA lpFindFileData);
The EntryPoint is not correct. So you are actually calling FindFirstFile instead of FindNextFile and it's hardly surprising that fails.
Specifying the EntryPoint when you don't need to is simply asking for trouble. And you've fallen right into the trap. I'd declare these imports like so:
[DllImport("Kernel32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
public static extern IntPtr FindFirstFile(string lpFileName,
ref WIN32_FIND_DATA lpFindFileData);
[DllImport("Kernel32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
public static extern bool FindNextFile(IntPtr hFindFile,
ref WIN32_FIND_DATA lpFindFileData);
[DllImport("Kernel32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
public static extern bool FindClose(IntPtr hFindFile);
Note that there's no need for the return attribute since UnmanagedType.Bool is the default.
And then you'd need to change the CharSet on the struct to be CharSet.Unicode to match. There's no point at all in opting for ANSI here.
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct WIN32_FIND_DATA
{
....
}
Finally, all of this code seems to me to be pointless. What's wrong with Directory.EnumerateFiles and Directory.EnumerateDirectories?

Loading/Injecting .Net Assembly into existing .net process?

In my situation i want to load a custom .net assembly into a running .net process's domain, for example Windows Explorer, What i have tried already is just injecting the assembly to explorer.exe but that doesn't seem to work for no obvious reason.
Injector Code:
public class CodeInjector
{
[DllImport("kernel32.dll", SetLastError = true)]
public static extern IntPtr OpenProcess(uint dwDesiredAccess, int bInheritHandle, uint dwProcessId);
[DllImport("kernel32.dll", SetLastError = true)]
public static extern int CloseHandle(IntPtr hObject);
[DllImport("kernel32.dll", SetLastError = true)]
public static extern IntPtr GetProcAddress(IntPtr hModule, string lpProcName);
[DllImport("kernel32.dll", SetLastError = true)]
public static extern IntPtr GetModuleHandle(string lpModuleName);
[DllImport("kernel32.dll", SetLastError = true)]
public static extern IntPtr VirtualAllocEx(IntPtr hProcess, IntPtr lpAddress, IntPtr dwSize, uint flAllocationType, uint flProtect);
[DllImport("kernel32.dll", SetLastError = true)]
public static extern int WriteProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, byte[] buffer, uint size, int lpNumberOfBytesWritten);
[DllImport("kernel32.dll", SetLastError = true)]
public static extern IntPtr CreateRemoteThread(IntPtr hProcess, IntPtr lpThreadAttribute, IntPtr dwStackSize, IntPtr lpStartAddress,
IntPtr lpParameter, uint dwCreationFlags, IntPtr lpThreadId);
private static CodeInjector _instance;
public static CodeInjector GetInstance
{
get { return _instance ?? (_instance = new CodeInjector()); }
}
public InjectionResult Inject(string sProcName, string sDllPath)
{
if (!File.Exists(sDllPath))
{
return InjectionResult.DllNotFound;
}
var procs = Process.GetProcesses();
var procId = (from t in procs where t.ProcessName == sProcName select (uint)t.Id).FirstOrDefault();
if (procId == 0)
{
return InjectionResult.ProcessNotFound;
}
if (!Inject(procId, sDllPath))
{
return InjectionResult.InjectionFailed;
}
return InjectionResult.InjectionSucceed;
}
private static bool Inject(uint pToBeInjected, string sDllPath)
{
var hndProc = OpenProcess((0x2 | 0x8 | 0x10 | 0x20 | 0x400), 1, pToBeInjected);
if (hndProc == IntPtr.Zero)
{
return false;
}
var lpLlAddress = GetProcAddress(GetModuleHandle("kernel32.dll"), "LoadLibraryA");
if (lpLlAddress == IntPtr.Zero)
{
return false;
}
var lpAddress = VirtualAllocEx(hndProc, (IntPtr)null, (IntPtr)sDllPath.Length, (0x1000 | 0x2000), 0X40);
if (lpAddress == IntPtr.Zero)
{
return false;
}
var bytes = Encoding.ASCII.GetBytes(sDllPath);
if (WriteProcessMemory(hndProc, lpAddress, bytes, (uint)bytes.Length, 0) == 0)
{
return false;
}
if (CreateRemoteThread(hndProc, (IntPtr)null, IntPtr.Zero, lpLlAddress, lpAddress, 0, (IntPtr)null) == IntPtr.Zero)
{
return false;
}
CloseHandle(hndProc);
return true;
}
}
As another option you can use existing library - ManagedInjector - https://github.com/cplotts/snoopwpf/tree/master/ManagedInjector . There is a tool snoopwpf that can show details of any WPF process, and it uses process injection for that. I used it some time ago and it worked well.
You need to build it, add to your project as reference and call like this:
Injector.Launch(someProcess.MainWindowHandle,
typeof(Loader).Assembly.Location,
typeof(Loader).FullName,
"Inject");
Loader is name of type that will be loaded into process and Inject is a static method that will be executed. In my case i had:
public class Loader
{
public static void Inject()
{
// i did CBT Hook on main window here
// and also displayed sample message box for debugging purposes
MessageBox.Show("Hello from another process");
}
}
That ManagedInjector is written in Managed C++ code. Basically it hooks own unmanaged C++ method as MessageHookProc and it will start specified assembly after injection and run specified method. It should work fine for both managed and unmanaged programs. In my case i used it for unmanaged program.
UPDATE
I tested it locally and it successfully injects my message box into explorer process under Windows 8.1 x64. I compiled ManagedInjector64-4.0 and my sample console project also has x64 in platform selection. Here is my working code:
class Program
{
static void Main(string[] args)
{
var proc = Process.GetProcessesByName("explorer").FirstOrDefault();
Injector.Launch(proc.MainWindowHandle, typeof(Loader).Assembly.Location, typeof(Loader).FullName, "Inject");
}
}
public class Loader
{
public static void Inject()
{
MessageBox.Show("Hello");
Task.Run(() =>
{
Thread.Sleep(3000);
MessageBox.Show("Hello again");
Thread.Sleep(5000);
MessageBox.Show("Hello again again");
});
}
}

How to dynamically load and unload a native DLL file?

I have a buggy third-party DLL files that, after some time of execution, starts throwing the access violation exceptions. When that happens I want to reload that DLL file. How do I do that?
Try this
[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 delegate 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);
Create a worker process that communicates via COM or another IPC mechanism. Then when the DLL dies, you can just restart the worker process.
Load the dll, call it, and then unload it till it's gone.
I've adapted the following code from the VB.Net example here.
[DllImport("powrprof.dll")]
static extern bool IsPwrHibernateAllowed();
[DllImport("kernel32.dll")]
static extern bool FreeLibrary(IntPtr hModule);
[DllImport("kernel32.dll")]
static extern bool LoadLibraryA(string hModule);
[DllImport("kernel32.dll")]
static extern bool GetModuleHandleExA(int dwFlags, string ModuleName, ref IntPtr phModule);
static void Main(string[] args)
{
Console.WriteLine("Is Power Hibernate Allowed? " + DoIsPwrHibernateAllowed());
Console.WriteLine("Press any key to continue...");
Console.ReadKey();
}
private static bool DoIsPwrHibernateAllowed()
{
LoadLibraryA("powrprof.dll");
var result = IsPwrHibernateAllowed();
var hMod = IntPtr.Zero;
if (GetModuleHandleExA(0, "powrprof", ref hMod))
{
while (FreeLibrary(hMod))
{ }
}
return result;
}

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