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GetUserName WinDDK

Posted on 2011-02-18
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Last Modified: 2013-12-14
There is an example in WinDDK called WatermakrUni. this example add watermark for pcl printer. watermark text is taken from user via user interface of printer proporties.

 i want to get username from windows so ican put it on page as watermark. When I try to compile source code with  GetUserName function,  compiler gives no error or warning.

But when I install plug in  it crash instantaly. program say acces vialotion.  when it comes to executeion of GetUserName functions. i am sending source code which I edit it

example in the this directory \WinDDK\7600.16385.1\src\print\oemdll\watermarkuni

error message =  0xC0000005: Access violation reading location 0x00000208.

GetUserName((LPWSTR)pOEMUIParam->pOEMOptItems[1].pSel,(LPDWORD)(MAX_PATH * sizeof(WCHAR))); // this is the part I added
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Question by:Tungaalper
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sarabande earned 1000 total points
ID: 34941182
access violation is cause the second argument of GetUserName is pointer to a long word that should take the length of the name. you made a cast of a constant to LPDWORD what crashes when the function assigns a value to the address the pointer is pointing to.

the statement also crashes if one of pOEMUIParam or pOEMUIParam->pOEMOptItems or pOEMUIParam->pOEMOptItems[1] or pOEMUIParam->pOEMOptItems[1].pSel  is invalid pointer or NULL.

i don't know why you use a so complicated variable for first argument of GetUserName which is simply a char or wchar_t buffer

so use

   TCHAR buffer[1024];
   DWORD len = sizeof(buffer) / sizeof(buffer[0]);
   BOOL ret = GetUserName(buffer, &len);

and it will work.

Sara
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