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Trouble with 'GetExitCodeProcess'

Posted on 1998-11-05
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Last Modified: 2008-02-01
When using the Shell function in conjuction with the OpenProcess API and the GetExitCodeProcess, the program errors out when the GetExitCodeProcess in encountered.  It also closes out the VB IDE. This was tested in VB5 and VB6 under Windows NT 4.0 with the same results.  I have declared the API's properly.  The function I shelled to is notepad.exe.

Declare statements:
Declare Function OpenProcess Lib "kernel32" (ByVal dwDesiredAccess as Long, ByVal bInheritHandle as Long, ByVal dwProcessId as Long) as Long
Declare Function GetExitCodeProcess Lib "kernel32" (ByVal hProcess as Long, ByVal lpExitCode as Long) as Long
Declare Function CloseHandle Lib "kernel32" (ByVal hObject as Long) as Long

Constants:
Private Const PROCESS_QUERY_INFORMATION = &H400&
Private Const STILL_ACTIVE = &H310&

Function:
Public Function WaitOnProgram() as Boolean
  Dim lExit as Long, lProg as Long, lReturnValue as Long
  Dim sShellCommand as String

  sShellCommand="c:\winnt\notepad.exe"
  lProg = OpenProcess(PROCESS_QUERY_INFORMATION, False, Shell(sShellCommand, vbNormalFocus))
  Do
    lReturnValue = GetExitCodeProcess(lProg, lExit)
    DoEvents
    Sleep 1000
  Loop While lExit = STILL_ACTIVE
  CloseHandle lProg
  WaitOnProgram = lExit
End Function

The error is a 'Start:VB5(6).exe - Application Error
The instruction at "0x77f199a9" referenced memory at "0x00000000". The memory could not be "written".
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Question by:RhinoDude
2 Comments
 
LVL 13

Accepted Solution

by:
Mirkwood earned 100 total points
ID: 1443358
I would blame the doevents. You are making a recursive call.
try replacing doevents with a timer.
To after OpenProcess, activate a timer
on the timer tick, test the exitcode
when the exitcode is still_activate deactive the timer and close the application.

Much more safe.
0
 

Author Comment

by:RhinoDude
ID: 1443359
After the OpenProcess I enabled the timer.

I changed the do loop to:
Do
  doevents
Loop While ProgramRunning

This enables repaint if necessary.

The timer routine is:
Dim lReturnValue As Long
Dim lExit As Long
     
'get status
lReturnValue = GetExitCodeProcess(lProg, lExit)
Sleep 100

lProg and STILL_ACTIVE were made public.
The Declare for the GetExitCodeProcess was made public.

thanks for the quick response!

0

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