Microsoft KB Archive/888087

= FIX: The SCardListReaders function may not correctly work when used in an RDP session in Windows CE .NET 4.0 =

Article ID: 888087

Article Last Modified on 5/27/2005

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APPLIES TO


 * Microsoft Windows CE .NET 4.0

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SYMPTOMS
When you run a Remote Desktop Protocol (RDP) session, and the server-side software calls the SCardListReaders function, a problem may occur if the following conditions are true:
 * The mszReaders parameter is set to NULL. The mszReaders parameter is the third parameter.
 * The pcchReaders parameter points to a DWORD that contains a large value. The pcchReaders parameter is the fourth parameter.

The SCardListReaders function may fail, and you may receive the following error message:

SCARD_E_NO_MEMORY

This is an unexpected problem. The current value for the DWORD variable that is pointed to by the pcchReaders parameter is supposed to be ignored if the mszReaders parameter is set to NULL.



Software update information
A supported software update is now available from Microsoft as Windows CE 4.0 Core OS QFE 888087. To resolve this problem immediately, click the following article number for information about obtaining Windows CE Platform Builder and core operating system software updates:

837392 How to locate core operating system fixes for Microsoft Windows CE Platform Builder products

Prerequisites
This update is supported only if all previously issued updates for this product have also been installed.

Restart requirement
After you install this update, you must perform a clean build of the whole platform. To clean the platform, click Clean on the Build menu. To build the platform, click Build Platform on the Build menu. You do not have to restart your computer after you apply this update.

Update replacement information
This update does not replace any other updates.

File information
The English version of this package has the file attributes (or later) that are listed in the following table.   Date         Time   Version            Size    File name --  06-Nov-2004  00:46  4.00            6,675,192  Wincepb40-041105-kb888087-armv4.exe 06-Nov-2004 00:51  4.00            6,675,192  Wincepb40-041105-kb888087-armv4i.exe 06-Nov-2004 00:47  4.00            6,650,616  Wincepb40-041105-kb888087-armv4t.exe 06-Nov-2004 00:47  4.00            6,277,880  Wincepb40-041105-kb888087-mips16.exe 06-Nov-2004 00:47  4.00            6,806,264  Wincepb40-041105-kb888087-mipsii.exe 06-Nov-2004 00:47  4.00            6,834,936  Wincepb40-041105-kb888087-mipsii_fp.exe 06-Nov-2004 00:51  4.00            6,974,200  Wincepb40-041105-kb888087-mipsiv.exe 06-Nov-2004 00:47  4.00            6,990,584  Wincepb40-041105-kb888087-mipsiv_fp.exe 06-Nov-2004 00:46  4.00            6,384,376  Wincepb40-041105-kb888087-sh3.exe 06-Nov-2004 00:50  4.00            6,384,376  Wincepb40-041105-kb888087-sh4.exe 06-Nov-2004 00:50  4.00            5,769,976  Wincepb40-041105-kb888087-x86.exe The English version of this update has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.   Date         Time                      Size    File name --

Path: Public\Rdp\Oak\Lib\Armv4\Debug 02-Nov-2004 02:50                 12,959,470  Mstscax.lib 02-Nov-2004 02:50                    356,352  Mstscax.pdb 02-Nov-2004 02:50                    217,088  Rdpdr.pdb

Path: Public\Rdp\Oak\Lib\Armv4\Retail 02-Nov-2004 02:46                  7,543,210  Mstscax.lib 02-Nov-2004 02:46                    339,968  Mstscax.pdb 02-Nov-2004 02:46                    217,088  Rdpdr.pdb

Path: Public\Rdp\Oak\Lib\Armv4i\Debug 02-Nov-2004 03:07                 12,980,656  Mstscax.lib 02-Nov-2004 03:07                    356,352  Mstscax.pdb 02-Nov-2004 03:07                    217,088  Rdpdr.pdb

Path: Public\Rdp\Oak\Lib\Armv4i\Retail 02-Nov-2004 03:03                  7,559,844  Mstscax.lib 02-Nov-2004 03:03                    339,968  Mstscax.pdb 02-Nov-2004 03:03                    217,088  Rdpdr.pdb

Path: Public\Rdp\Oak\Lib\Armv4t\Debug 02-Nov-2004 02:59                 12,347,864  Mstscax.lib 02-Nov-2004 02:59                    356,352  Mstscax.pdb 02-Nov-2004 02:58                    217,088  Rdpdr.pdb

Path: Public\Rdp\Oak\Lib\Armv4t\Retail 02-Nov-2004 02:55                  7,523,054  Mstscax.lib 02-Nov-2004 02:55                    339,968  Mstscax.pdb 02-Nov-2004 02:54                    217,088  Rdpdr.pdb

Path: Public\Rdp\Oak\Lib\Mips16\Debug 02-Nov-2004 03:33                 12,261,372  Mstscax.lib 02-Nov-2004 03:33                    356,352  Mstscax.pdb 02-Nov-2004 03:32                    217,088  Rdpdr.pdb

Path: Public\Rdp\Oak\Lib\Mips16\Retail 02-Nov-2004 03:29                  7,126,936  Mstscax.lib 02-Nov-2004 03:29                    339,968  Mstscax.pdb 02-Nov-2004 03:28                    217,088  Rdpdr.pdb

Path: Public\Rdp\Oak\Lib\Mipsii\Debug 02-Nov-2004 03:16                 13,464,132  Mstscax.lib 02-Nov-2004 03:16                    356,352  Mstscax.pdb 02-Nov-2004 03:15                    217,088  Rdpdr.pdb

Path: Public\Rdp\Oak\Lib\Mipsii\Retail 02-Nov-2004 03:12                  7,959,918  Mstscax.lib 02-Nov-2004 03:12                    339,968  Mstscax.pdb 02-Nov-2004 03:11                    217,088  Rdpdr.pdb

Path: Public\Rdp\Oak\Lib\Mipsii_fp\Debug 02-Nov-2004 03:42                 13,480,130  Mstscax.lib 02-Nov-2004 03:42                    364,544  Mstscax.pdb 02-Nov-2004 03:41                    217,088  Rdpdr.pdb

Path: Public\Rdp\Oak\Lib\Mipsii_fp\Retail 02-Nov-2004 03:37                  7,975,124  Mstscax.lib 02-Nov-2004 03:37                    339,968  Mstscax.pdb 02-Nov-2004 03:37                    217,088  Rdpdr.pdb

Path: Public\Rdp\Oak\Lib\Mipsiv\Debug 02-Nov-2004 03:25                 13,692,678  Mstscax.lib 02-Nov-2004 03:24                    356,352  Mstscax.pdb 02-Nov-2004 03:24                    217,088  Rdpdr.pdb

Path: Public\Rdp\Oak\Lib\Mipsiv\Retail 02-Nov-2004 03:20                  8,135,666  Mstscax.lib 02-Nov-2004 03:20                    339,968  Mstscax.pdb 02-Nov-2004 03:20                    217,088  Rdpdr.pdb

Path: Public\Rdp\Oak\Lib\Mipsiv_fp\Debug 02-Nov-2004 03:50                 13,711,020  Mstscax.lib 02-Nov-2004 03:50                    364,544  Mstscax.pdb 02-Nov-2004 03:49                    217,088  Rdpdr.pdb

Path: Public\Rdp\Oak\Lib\Mipsiv_fp\Retail 02-Nov-2004 03:46                  8,151,084  Mstscax.lib 02-Nov-2004 03:46                    339,968  Mstscax.pdb 02-Nov-2004 03:45                    217,088  Rdpdr.pdb

Path: Public\Rdp\Oak\Lib\Sh3\Debug 02-Nov-2004 02:33                 11,720,534  Mstscax.lib 02-Nov-2004 02:33                    356,352  Mstscax.pdb 02-Nov-2004 02:33                    217,088  Rdpdr.pdb

Path: Public\Rdp\Oak\Lib\Sh3\Retail 02-Nov-2004 02:29                  7,083,148  Mstscax.lib 02-Nov-2004 02:29                    339,968  Mstscax.pdb 02-Nov-2004 02:29                    217,088  Rdpdr.pdb

Path: Public\Rdp\Oak\Lib\Sh4\Debug 02-Nov-2004 02:42                 11,721,344  Mstscax.lib 02-Nov-2004 02:42                    356,352  Mstscax.pdb 02-Nov-2004 02:41                    217,088  Rdpdr.pdb

Path: Public\Rdp\Oak\Lib\Sh4\Retail 02-Nov-2004 02:38                  7,073,840  Mstscax.lib 02-Nov-2004 02:38                    339,968  Mstscax.pdb 02-Nov-2004 02:37                    217,088  Rdpdr.pdb

Path: Public\Rdp\Oak\Lib\X86\Debug 02-Nov-2004 02:25                 11,052,970  Mstscax.lib 02-Nov-2004 02:25                    356,352  Mstscax.pdb 02-Nov-2004 02:24                    217,088  Rdpdr.pdb

Path: Public\Rdp\Oak\Lib\X86\Retail 02-Nov-2004 02:21                  6,624,648  Mstscax.lib 02-Nov-2004 02:21                    339,968  Mstscax.pdb 02-Nov-2004 02:21                    217,088  Rdpdr.pdb



MORE INFORMATION
You want to use NULL for the mszReaders parameter that is the third parameter. You do this so that you can query for the size that is required for the buffer. The size that is required for the buffer has to be allocated before you allocate the buffer and then make another call to the SCardListReaders function.



WORKAROUND
Because the technique that is mentioned in the &quot;More Information&quot; section may fail, the alternative is to set the pcchReaders parameter to the SCARD_AUTOALLOCATE length designator. This makes the SCardListReaders function allocate a buffer that is the correct size and then return the requested list of readers.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.

Keywords: kbbug kbfix kbqfe KB888087

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