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Editorial Team
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Asked: 2026-05-17T21:18:32+00:00

I wish to implement IPC using Named Shared Memory. To do this, one of

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I wish to implement IPC using Named Shared Memory.

To do this, one of the steps is getting a handle to a Mapping Memory Object, using CreateFileMapping().

I do it exactly as MSDN website reccommends: http://msdn.microsoft.com/en-us/library/aa366551(v=VS.85).aspx:

hFileMappingHandle = CreateFileMapping
    (
        INVALID_HANDLE_VALUE,      // use paging file
        NULL,                      // default security 
        PAGE_READWRITE,            // read/write access
        0,            // maximum object size (high-order DWORD) 
        256,            // maximum object size (low-order DWORD)  
        "Global\\MyFileMappingObject"          // name of mapping object
    ); 
DWORD dwError = GetLastError();

However, the handle returned is always 0x0, and the System Error Code returned is: 0x5 (Access Denied.)

  • Only Named Memory Sharing desired (not file sharing).
  • Windows 7 x64 bit OS
  • Administrator’s user rights available
  • Developed Application: 64bit Plug-In application (.dll)

Does anybody have the same experience, and a way to fix it, please? I use MSDN site as my reference, so I to not think, there is problem in the code.

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1 Answer

  1. Editorial Team

    Looks like you don’t have enough privileges.

    From MSDN:

    Creating a file mapping object in the
    global namespace from a session other
    than session zero requires the
    SeCreateGlobalPrivilege privilege. For
    more information, see Kernel Object
    Namespaces.

    …

    The creation of a file-mapping object
    in the global namespace, by using
    CreateFileMapping, from a session
    other than session zero is a
    privileged operation. Because of this,
    an application running in an arbitrary
    Remote Desktop Session Host (RD
    Session Host) server session must have
    SeCreateGlobalPrivilege enabled in
    order to create a file-mapping object
    in the global namespace successfully.
    The privilege check is limited to the
    creation of file-mapping objects, and
    does not apply to opening existing
    ones. For example, if a service or the
    system creates a file-mapping object,
    any process running in any session can
    access that file-mapping object
    provided that the user has the
    necessary access.

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