HOWTO:Constants in OpenProcess API dsDesiredAccess Parameter

Last reviewed: November 10, 1997
Article ID: Q172273

The information in this article applies to:

Microsoft Visual Basic Learning, Professional, and Enterprise Editions for Windows, version 5.0
Microsoft Visual Basic Standard, Professional, and Enterprise Editions, 32-bit only, for Windows, version 4.0

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:

   ARTICLE-ID: Q129797
   TITLE     : HOWTO: Launch a Win32 Application from Visual Basic

   ARTICLE-ID: Q150767
   TITLE     : HOWTO: Redirect Standard I/O of a Console Application

Keywords          : APrgOther kbhowto
Version           : WINDOWS:4.0, 5.0
Platform          : WINDOWS
Hardware          : x86
Issue type        : kbhowto

================================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Last reviewed: November 10, 1997
© 1998 Microsoft Corporation. All rights reserved. Terms of Use.