[?] ERROR_HOOK_NEEDS_HMOD during installing system hook

  • Thread starter Thread starter Gambero
  • Start date Start date
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Gambero

Hi, i want to do system hook WH_SYSMSGFILTER,
my code is:

IntPtr hMod =
Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().GetModules()[0]);
//install hook
hSysMsgHook = Api.User32.SetWindowsHookEx(WH_SYSMSGFILTER,
SysMsgHookProcedure, hMod, 0);
//If SetWindowsHookex fails.
if (hSysMsgHook == 0)
{
int errorCode = Marshal.GetLastWin32Error();
//do cleanup
Stop(false, false, true, false);
//Initializes and throws a new instance of the Win32Exception class with
the specified error.
throw new Win32Exception(errorCode);
}


hMod is valid but the api return code is ERROR_HOOK_NEEDS_HMOD!
other types of hook like WH_KEYBOARD_LL or WH_MOUSE_LL works fine!
my machine is windows vista
what's wrong?
Thanks
 
Hi, i want to do system hook WH_SYSMSGFILTER,

You can't implement global system hooks in managed code (with the
exception of the _LL types). Choose another language that compiles to
native code and that doesn't require any runtime library to run.


Mattias
 
You can't implement global system hooks in managed code (with the
exception of the _LL types). Choose another language that compiles to
native code and that doesn't require any runtime library to run.
Click to expand...

but i don't use managed code! i use windows api througth pinvoke:

[DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention =
CallingConvention.StdCall, SetLastError = true)]
public static extern int SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr
hMod, int dwThreadId);

you are sure that i can't do that? this works fine for keyboard and mouse...
what is the problem for WH_SYSMSGFILTER?
do you have any documentation that report this limitation?
thanks!
 
Gambero said:
You can't implement global system hooks in managed code (with the
exception of the _LL types). Choose another language that compiles to
native code and that doesn't require any runtime library to run.
Click to expand...

but i don't use managed code! i use windows api througth pinvoke:

[DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention =
CallingConvention.StdCall, SetLastError = true)]
public static extern int SetWindowsHookEx(int idHook, HookProc lpfn,
IntPtr hMod, int dwThreadId);

you are sure that i can't do that? this works fine for keyboard and
mouse... what is the problem for WH_SYSMSGFILTER?
do you have any documentation that report this limitation?
thanks!
Click to expand...


Mattias is right, your hook procedure is managed code and such procedure is
not exported as a native function, which is an absolute requirement to be
called globally.

See: "Global hooks are not supported in the .NET Framework" at the bottom of
the following KB article for more detailed info:
http://support.microsoft.com/kb/318804


Willy.
 
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