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tricky808

DllCall OpenThread SuspendThread ResumeThread issue

5 posts in this topic

I have this code I'm using to try and suspend or resume a thread and I can't get it to work...

For my function params, I'm calling callThreads(3436, "suspend").

In this case 3436 is the decimal equivalent of the threadID I want to suspend (an AutoIt process).

I am using Number() as my conversion function from a string value that is '3436'.

In other words, my function is being called like this: callThreads(Number($szThreadID), "suspend"))...

Func callThreads($iThread, $szAction); gets a thread handle and performs a suspend or resume function on it
  ; setup constants and variables
   Const $THREAD_SUSPEND_RESUME = 0x0002
   Local $hThread, $iThreadAction
   
  ; get the thread handle
   $hThread = DllCall("kernel32.dll", "hwnd", "OpenThread", "int", $THREAD_SUSPEND_RESUME, "int", 0, "int", $iThread)

  ; return an error if there is a problem getting the thread
   If $hThread = 0 Then Return ("" & SetError(1))

  ; perform a suspend or resume action on the thread
   If StringLower($szAction) = "suspend" Then
      $iThreadAction = DllCall("kernel32.dll", "int", "SuspendThread", "hwnd", $hThread)
      If @error Then MsgBox(0,"suspendthread error")
   ElseIf StringLower($szAction) = "resume" Then
      $iThreadAction = DllCall("kernel32.dll", "int", "ResumeThread", "hwnd", $hThread)
      If @error Then MsgBox(0,"resumethread error")
   EndIf

  ; close the thread handle
   $hThread = 0

  ; throw an error if there is a problem
   If $iThreadAction = -1 Then Return ("" & SetError(1))
EndFunc

No errors are being returned, but my thread is not suspending. I'm thinking maybe it's because I'm not converting the threadID to a dword value. Can someone tell me where I'm going wrong with this?


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Re-read the documentation for DllCall() again. Pay particular attention to the return value section. Also re-read MSDN. I don't imagine just writing "$hThread = 0" is properly closing the thread. I'm sure OpenThread() mentions something about CloseHandle() needing to be called. Lastly, you might want to read how operator = works. The calls to StringLower() are not necessary.

Those are the 3 significant problems I see off-hand.

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Oops, yeah forgot it returned an array...

Good call on the CloseHandle, you preempted any future issues I would've had after fixing the handle/array/return value deal...

and yeah, the stringlower thing is something I do to prevent me sabotaging myself when I call the function later in my code. I guess I need to quit enabling myself and pay attention to my case when I type.

Thanks for the fishing lessons!


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Oops, yeah forgot it returned an array...

Good call on the CloseHandle, you preempted any future issues I would've had after fixing the handle/array/return value deal...

and yeah, the stringlower thing is something I do to prevent me sabotaging myself when I call the function later in my code. I guess I need to quit enabling myself and pay attention to my case when I type.

Thanks for the fishing lessons!

You got 2 out of 3 right.

Run the following code to understand the 3rd.

If "ENABLE" = "enable" Then MsgBox(4096, "", "I bet operator = is case insensitive.")
If "ENABLE" == "enable" Then 
    MsgBox(4096, "", "If this is visible, AutoIt is broke.")
Else
    MsgBox(4096, "", "It looks lile operator == is case sensitive.")
EndIf

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You got 2 out of 3 right.

Run the following code to understand the 3rd.

If "ENABLE" = "enable" Then MsgBox(4096, "", "I bet operator = is case insensitive.")
If "ENABLE" == "enable" Then 
    MsgBox(4096, "", "If this is visible, AutoIt is broke.")
Else
    MsgBox(4096, "", "It looks lile operator == is case sensitive.")
EndIf
Understood. Thank you for explaining that nuance...

Aut viam inveniam aut faciam

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