SCardListCardsW function (winscard.h)

Article
02/09/2023

The SCardListCards function searches the smart card database and provides a list of named cards previously introduced to the system by the user.

The caller specifies an ATR string, a set of interface identifiers (GUIDs), or both. If both an ATR string and an identifier array are supplied, the cards returned will match the ATR string supplied and support the interfaces specified.

Syntax

LONG SCardListCardsW(
  [in]           SCARDCONTEXT hContext,
  [in, optional] LPCBYTE      pbAtr,
  [in]           LPCGUID      rgquidInterfaces,
  [in]           DWORD        cguidInterfaceCount,
  [out]          WCHAR        *mszCards,
  [in, out]      LPDWORD      pcchCards
);

Parameters

[in] hContext

Handle that identifies the resource manager context for the query. The resource manager context can be set by a previous call to SCardEstablishContext.

If this parameter is set to NULL, the search for cards is not limited to any context.

[in, optional] pbAtr

Address of an ATR string to compare to known cards, or NULL if no ATR matching is to be performed.

[in] rgquidInterfaces

Array of identifiers (GUIDs), or NULL if no interface matching is to be performed. When an array is supplied, a card name will be returned only if all the specified identifiers are supported by the card.

[in] cguidInterfaceCount

Number of entries in the rgguidInterfaces array. If rgguidInterfaces is NULL, then this value is ignored.

[out] mszCards

Multi-string that lists the smart cards found. If this value is NULL, SCardListCards ignores the buffer length supplied in pcchCards, returning the length of the buffer that would have been returned if this parameter had not been NULL to pcchCards and a success code.

[in, out] pcchCards

Length of the mszCards buffer in characters. Receives the actual length of the multi-string structure, including all trailing null characters. If the buffer length is specified as SCARD_AUTOALLOCATE, then mszCards is converted to a pointer to a byte pointer, and receives the address of a block of memory containing the multi-string structure. This block of memory must be deallocated with SCardFreeMemory.

Return value

This function returns different values depending on whether it succeeds or fails.

Return code	Description
Success	SCARD_S_SUCCESS.
Failure	An error code. For more information, see Smart Card Return Values.

Remarks

This function is not redirected, but calling the function when inside a Remote Desktop session will not result in an error. It only means that the result will be from the remote computer instead of the local computer.

To return all smart cards introduced to the subsystem, set pbAtr and rgguidInterfaces to NULL.

The SCardListCards function is a database query function. For more information on other database query functions, see Smart Card Database Query Functions.

Calling this function should be done outside of a transaction. If an application begins a transaction with the SCardBeginTransaction function and then calls this function, it resets the hCard parameter (of type SCARDHANDLE) of the SCardBeginTransaction function.

Windows Server 2008 R2 and Windows 7: Calling this function within a transaction could result in your computer becoming unresponsive.

Windows Server 2008, Windows Vista, Windows Server 2003 and Windows XP: Not applicable.

Examples

The following example shows listing of the smart cards.

LPTSTR pmszCards = NULL;
LPTSTR pCard;
LONG lReturn;
DWORD cch = SCARD_AUTOALLOCATE;

// Retrieve the list of cards.
lReturn = SCardListCards(NULL,
                         NULL,
                         NULL,
                         NULL,
                         (LPTSTR)&pmszCards,
                         &cch );
if ( SCARD_S_SUCCESS != lReturn )
{
    printf("Failed SCardListCards\n");
    exit(1); // Or other appropriate error action
}
// Do something with the multi string of cards.
// Output the values.
// A double-null terminates the list of values.
pCard = pmszCards;
while ( '\0' != *pCard )
{
    // Display the value.
    printf("%S\n", pCard );
    // Advance to the next value.
    pCard = pCard + wcslen(pCard) + 1;
}

// Remember to free pmszCards (by calling SCardFreeMemory).
// ...

Note

The winscard.h header defines SCardListCards as an alias which automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.

Requirements

Requirement	Value
Minimum supported client	Windows XP [desktop apps only]
Minimum supported server	Windows Server 2003 [desktop apps only]
Target Platform	Windows
Header	winscard.h
Library	Winscard.lib
DLL	Winscard.dll

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