[Bug 27339] improper last error code set by GetUserNameW

http://bugs.winehq.org/show_bug.cgi?id=27339

--- Comment #3 from [e-mail] 2011-05-31 12:17:14 CDT ---
Hi,

That same problem exists in GetUserNameA in that same file.

If I set too small a buffer and invoke GetUserNameA under Windows, it returns
122 "ERROR_INSUFFICIENT_BUFFER" and not 234 "ERROR_MORE_DATA".

Here is the problem snippet of code from GetUserNameA

53 BOOL WINAPI
 54 GetUserNameA( LPSTR lpszName, LPDWORD lpSize )
 55 {

...

65     ret = GetUserNameW( buffer, &sizeW );
 66     if (ret)
 67     {
 68         if (!(*lpSize = WideCharToMultiByte( CP_ACP, 0, buffer, -1,
lpszName, *lpSize, NULL, NULL )))
 69         {
 70             *lpSize = WideCharToMultiByte( CP_ACP, 0, buffer, -1, NULL, 0,
NULL, NULL );
 71             SetLastError( ERROR_MORE_DATA );
 72             ret = FALSE;
 73         }
 74     }
 75     else *lpSize = sizeW * 2;
 76     HeapFree( GetProcessHeap(), 0, buffer );
 77     return ret;
 78 }

GetUserNameA knows to loop and double its own internal buffer size until it
holds the username generated by GetUserNameW but still has to return
"ERROR_INSUFFICIENT_BUFFER" to its caller to tell it to grow the size of its
buffer to match otherwise there is no way to return the username value to the
caller.

So "ERROR_MORE_DATA" should be changed to "ERROR_INSUFFICIENT_BUFFER" here as
well to match what GetLastError on Windows returns for GetUserNameA.

If you need an modified python test program that shows this error, please let
me know and I will attach it.