Q172273: HOWTO:Constants in OpenProcess API dsDesiredAccess Parameter

Article: Q172273
Product(s): Microsoft Visual Basic for Windows
Version(s): WINDOWS:4.0, 5.0
Operating System(s): 
Keyword(s): kbGrpDSVBDB
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Learning Edition for Windows, version 5.0 
- Microsoft Visual Basic Professional Edition for Windows, version 5.0 
- Microsoft Visual Basic Enterprise Edition for Windows, version 5.0 
- Microsoft Visual Basic Standard Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0 
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SUMMARY
=======

The API text viewer included with Visual Basic 4.0 does not define the constants
used in the OpenProcess API. The OpenProcess API is used to get a handle to a
running process from a process ID. The existing samples in the Microsoft
Knowledge Base define one of the possible constants, SYNCHRONIZE, but the other
values may be of use in special situations.

MORE INFORMATION
================

The constants are:

PROCESS_ALL_ACCESS   =&H1F0FFF Specifies all possible access flags for
           the process object.

PROCESS_CREATE_THREAD   =&H2  Enables using the process handle in the
           CreateRemoteThread function to create a thread in the process.

PROCESS_DUP_HANDLE   =&H40 Enables using the process handle as either
           the source or target process in the DuplicateHandle function to
           duplicate a handle.

PROCESS_QUERY_INFORMATION =&H400 Enables using the process handle in the
           GetExitCodeProcess and GetPriorityClass functions to read
           information from the process object.

PROCESS_SET_INFORMATION =&H200   Enables using the process handle in the
           SetPriorityClass function to set the priority class of the
           process.

PROCESS_TERMINATE =&H1  Enables using the process handle in the
           TerminateProcess function to terminate the process.

PROCESS_VM_OPERATION =&H8  Enables using the process handle in the
           VirtualProtectEx and WriteProcessMemory functions to modify the
           virtual memory of the process.

PROCESS_VM_READ      =&H10 Enables using the process handle in the
           ReadProcessMemory function to read from the virtual memory of
           the process.

PROCESS_VM_WRITE  =&H20 Enables using the process handle in the
           WriteProcessMemory function to write to the virtual memory of
           the process.

SYNCHRONIZE    =&H100000 Enables using the process handle in any of the
           wait functions to wait for the process to terminate.

If you need to create a handle that is to be used for more than one type of
access, you should add the desired access type parameters together. For example,
to get a handle to use with WaitForSingleObject and GetExitCodeProcess, you
would use:

     hProcess = OpenProcess(PROCESS_QUERY_INFORMATION+SYNCHRONIZE,FALSE,pid)

REFERENCES
==========

For additional information, please see the following article(s) in the Microsoft
Knowledge Base:

  Q129797 : HOWTO: Launch a Win32 Application from Visual Basic

  Q150767 : HOWTO: Redirect Standard I/O of a Console Application


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Keywords          : kbGrpDSVBDB 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVBA500 kbVB500 kbVB400Search kbVB400
Version           : WINDOWS:4.0, 5.0
Hardware          : x86
Issue type        : kbhowto

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