SCard Zig Reference Documentation
SCard
Current Version: 11.6.1
Chilkat.SCard
Enumerate available PC/SC smart card readers and identify the reader the
application should use.
Connect to a reader/card, check card presence and status, and manage the
active PC/SC connection.
Send APDU commands directly to the card and receive the raw response
bytes and status words.
Issue lower-level reader control commands when supported by the reader
driver and PC/SC environment.
Monitor reader or card status changes so applications can detect card
insertion, removal, or state changes.
Use PC/SC transactions for coordinated card access and inspect detailed
error information when reader or card operations fail.
For an extended overview, see
SCard Class Overview.
Communicate directly with smart card readers and cards through PC/SC.
Chilkat.SCard is the low-level PC/SC smart card interface for
applications that need direct reader and card communication. It supports
reader discovery, reader connection, card status checking, APDU transmission,
reader-control commands, status-change monitoring, transactions, and
diagnostic access to underlying PC/SC errors. Use this class when the
application needs APDU-level control rather than a higher-level certificate,
minidriver, or PKCS#11 abstraction.
Reader discovery
Connect to cards
Transmit APDUs
Reader-control commands
Status monitoring
Transactions and diagnostics
Chilkat.SCard for direct PC/SC
reader and APDU-level work; use Chilkat.ScMinidriver for
card-minidriver certificate and key-container operations, and
Chilkat.Pkcs11 for PKCS#11 token or HSM sessions.
Object Creation
// Add the package once:
// zig fetch --save https://chilkatdownload.com/11.6.1/chilkat-zig-11.6.1.tar.gz
// and in build.zig:
// const chilkat = b.dependency("chilkat", .{ .target = target, .optimize = optimize });
// exe.root_module.addImport("chilkat", chilkat.module("chilkat"));
const chilkat = @import("chilkat");
// Once per process, before any other Chilkat call:
try chilkat.unlockBundle("Anything for 30-day trial");
const s_card = try chilkat.SCard.init();
defer s_card.deinit();Creates the underlying native Chilkat object. SCard is a one-pointer struct passed by value; copying it copies the handle (two names for one object). Returns error.OutOfMemory if the library could not allocate the object. Use an object from one thread at a time; it may be handed from one thread to another.
Releases the native object. Call it exactly once per object (usually with defer); the handle is invalid afterwards. Objects returned by methods are owned by the caller too and are released the same way.
Wraps a handle obtained from the C API (chilkat.c.CkSCard), taking ownership of it. The struct's handle field goes the other way, for anything the Zig API does not cover.
Errors and memory
Methods that can fail return an error union: a method whose only outcome is success or failure returns Error!void; a method producing a string returns (Error || Allocator.Error)![:0]u8; a method producing an object returns Error!T. chilkat.Error is error{ChilkatFailed}; the reason for a failure is in getLastErrorText, and the object remains usable. Properties never fail, and methods that answer a question (hasMember, isUnlocked, ...) return a plain bool.
String arguments are [:0]const u8 (UTF-8; string literals can be passed as is). String results are copies allocated with the allocator argument and owned by the caller, so they stay valid across later calls on the same object.
const text = s_card.someMethod(allocator, ...) catch |err| {
const why = try s_card.getLastErrorText(allocator);
defer allocator.free(why);
std.debug.print("{s}\n", .{why});
return err;
};
defer allocator.free(text);Properties
ActiveProtocol
pub fn getActiveProtocol(self: SCard, allocator: Allocator) Allocator.Error![:0]u8
The name of the active protocol if connected smart card reader, or an empty string if not connected. Possible values are T0, T1, raw, undefined, or if not connected to a reader.
CardAtr
pub fn getCardAtr(self: SCard, allocator: Allocator) Allocator.Error![:0]u8
This is the Current ATR of a card in the connected reader.
topConnectedReader
pub fn getConnectedReader(self: SCard, allocator: Allocator) Allocator.Error![:0]u8
The name of the currently connected smart card reader, or an empty string if not connected.
topContext
pub fn getContext(self: SCard, allocator: Allocator) Allocator.Error![:0]u8
Contains the string user or system if this object has established a context (by calling EstablishContext). Contains the empty string if no context is established.
DebugLogFilePath
pub fn getDebugLogFilePath(self: SCard, allocator: Allocator) Allocator.Error![:0]u8
pub fn setDebugLogFilePath(self: SCard, value: [:0]const u8) void
If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.
Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.
Possible causes of hangs include:
- A timeout property set to 0, indicating an infinite timeout.
- A hang occurring within an event callback in the application code.
- An internal bug in the Chilkat code causing the hang.
LastErrorHtml
pub fn getLastErrorHtml(self: SCard, allocator: Allocator) Allocator.Error![:0]u8
Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastErrorText
pub fn getLastErrorText(self: SCard, allocator: Allocator) Allocator.Error![:0]u8
Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
LastErrorXml
pub fn getLastErrorXml(self: SCard, allocator: Allocator) Allocator.Error![:0]u8
Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastMethodSuccess
pub fn getLastMethodSuccess(self: SCard) bool
pub fn setLastMethodSuccess(self: SCard, value: bool) void
Indicates the success or failure of the most recent method call: true means success, false means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages. Note: This property does not apply to methods that return integer values or to boolean-returning methods where the boolean does not indicate success or failure.
PcscLibPath
pub fn getPcscLibPath(self: SCard, allocator: Allocator) Allocator.Error![:0]u8
pub fn setPcscLibPath(self: SCard, value: [:0]const u8) void
For Linux systems only. Specifies the full path of the libpcsclite.so shared lib. This property should only be used if the libpcsclite.so is in a non-standard location or if Chilkat cannot automatically located it.
topReaderStatus
pub fn getReaderStatus(self: SCard, allocator: Allocator) Allocator.Error![:0]u8
The current status of the connected reader. Possible values are:
absent- There is no card in the reader.present- There is a card in the reader, but it has not been moved into position for use.swallowed- There is a card in the reader in position for use. The card is not powered.powered- Power is being provided to the card, but the reader driver is unaware of the mode of the card.negotiable- The card has been reset and is awaiting PTS negotiation.specific- The card has been reset and specific communication protocols have been established.
ScardError
pub fn getScardError(self: SCard, allocator: Allocator) Allocator.Error![:0]u8
The last error returned by an underlying PC/SC function. Can be one of the following:
SCARD_W_REMOVED_CARD- The smart card has been removed, so that further communication is not possible.SCARD_W_RESET_CARD- The smart card has been reset, so any shared state information is invalid.
...
VerboseLogging
pub fn getVerboseLogging(self: SCard) bool
pub fn setVerboseLogging(self: SCard, value: bool) void
If set to true, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is false. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.
Version
pub fn getVersion(self: SCard, allocator: Allocator) Allocator.Error![:0]u8
Methods
BeginTransaction
Establishes a temporary exclusive access mode for doing a series of commands in a transaction.
Returns error.ChilkatFailed on failure; getLastErrorText explains why.
CheckStatus
Check the current status of the currently connected reader. Calling this method updates the ReaderStatus, ActiveProtocol, and CardAtr properties. If this method returns false, none of the properties are updated.
Connect
Establish a connection to a reader. The reader is the name of a reader returned from ListReaders. The share_mode can be shared, exclusive, or direct. The preferred_protocol can be 0 (valid only if the shareMode = direct), T0, T1, raw, or no_preference. (No preference is effectively T0 or T1.)
If successful, the state of this object instance is that it's connected to the reader.
Disconnect
Terminates a connection with a reader. The disposition can be one of the following values:
leave: Do nothing.reset: Reset the card (warm reset).unpower: Power down the card (cold reset).eject: Eject the card.
Returns error.ChilkatFailed on failure; getLastErrorText explains why.
EndTransaction
Ends a previously begun transaction. The disposition is the action to be taken on the reader, and can be leave which is to do nothing, reset, unpower, or eject.
Returns error.ChilkatFailed on failure; getLastErrorText explains why.
EstablishContext
Creates an Application Context to the PC/SC Resource Manager. This must be the first WinSCard function called in a PC/SC application. The scope can be user or system. After calling, this object will have context and all other methods will use the established context. The Context property will hold the value user or system if context was established, or will be empty if no context was established.
Returns error.ChilkatFailed on failure; getLastErrorText explains why.
FindSmartcards
Returns JSON containing information about the smartcards currently inserted into readers.
Returns error.ChilkatFailed on failure; getLastErrorText explains why.
GetAttrib
Get an attribute from the IFD Handler (reader driver).
The attr can be one of the following:
ASYNC_PROTOCOL_TYPESATR_STRINGCHANNEL_IDCHARACTERISTICSCURRENT_BWTCURRENT_CLKCURRENT_CWTCURRENT_DCURRENT_EBC_ENCODINGCURRENT_FCURRENT_IFSCCURRENT_IFSDCURRENT_IO_STATECURRENT_NCURRENT_PROTOCOL_TYPECURRENT_WDEFAULT_CLKDEFAULT_DATA_RATEDEVICE_FRIENDLY_NAMEDEVICE_IN_USEDEVICE_SYSTEM_NAMEDEVICE_UNITESC_AUTHREQUESTESC_CANCELESC_RESETEXTENDED_BWTICC_INTERFACE_STATUSICC_PRESENCEICC_TYPE_PER_ATRMAX_CLKMAX_DATA_RATEMAX_IFSDMAXINPUTPOWER_MGMT_SUPPORTSUPRESS_T1_IFS_REQUESTSYNC_PROTOCOL_TYPESUSER_AUTH_INPUT_DEVICEUSER_TO_CARD_AUTH_DEVICEVENDOR_IFD_SERIAL_NOVENDOR_IFD_TYPEVENDOR_IFD_VERSIONVENDOR_NAME
The attribute data is returned in bd.
Returns error.ChilkatFailed on failure; getLastErrorText explains why.
GetAttribStr
Get a string typed attribute from the IFD Handler (reader driver).
The attr can be one of the following, but should be limited to the particular attributes that return string values.
ASYNC_PROTOCOL_TYPESATR_STRINGCHANNEL_IDCHARACTERISTICSCURRENT_BWTCURRENT_CLKCURRENT_CWTCURRENT_DCURRENT_EBC_ENCODINGCURRENT_FCURRENT_IFSCCURRENT_IFSDCURRENT_IO_STATECURRENT_NCURRENT_PROTOCOL_TYPECURRENT_WDEFAULT_CLKDEFAULT_DATA_RATEDEVICE_FRIENDLY_NAMEDEVICE_IN_USEDEVICE_SYSTEM_NAMEDEVICE_UNITESC_AUTHREQUESTESC_CANCELESC_RESETEXTENDED_BWTICC_INTERFACE_STATUSICC_PRESENCEICC_TYPE_PER_ATRMAX_CLKMAX_DATA_RATEMAX_IFSDMAXINPUTPOWER_MGMT_SUPPORTSUPRESS_T1_IFS_REQUESTSYNC_PROTOCOL_TYPESUSER_AUTH_INPUT_DEVICEUSER_TO_CARD_AUTH_DEVICEVENDOR_IFD_SERIAL_NOVENDOR_IFD_TYPEVENDOR_IFD_VERSIONVENDOR_NAME
Returns error.ChilkatFailed on failure; getLastErrorText explains why. The string is allocated with allocator and owned by the caller (defer allocator.free(s)).
GetAttribUint
Get an unsigned integer typed attribute from the IFD Handler (reader driver).
The attr can be one of the following, but should be limited to the particular attributes that return unsigned integer values.
ASYNC_PROTOCOL_TYPESATR_STRINGCHANNEL_IDCHARACTERISTICSCURRENT_BWTCURRENT_CLKCURRENT_CWTCURRENT_DCURRENT_EBC_ENCODINGCURRENT_FCURRENT_IFSCCURRENT_IFSDCURRENT_IO_STATECURRENT_NCURRENT_PROTOCOL_TYPECURRENT_WDEFAULT_CLKDEFAULT_DATA_RATEDEVICE_FRIENDLY_NAMEDEVICE_IN_USEDEVICE_SYSTEM_NAMEDEVICE_UNITESC_AUTHREQUESTESC_CANCELESC_RESETEXTENDED_BWTICC_INTERFACE_STATUSICC_PRESENCEICC_TYPE_PER_ATRMAX_CLKMAX_DATA_RATEMAX_IFSDMAXINPUTPOWER_MGMT_SUPPORTSUPRESS_T1_IFS_REQUESTSYNC_PROTOCOL_TYPESUSER_AUTH_INPUT_DEVICEUSER_TO_CARD_AUTH_DEVICEVENDOR_IFD_SERIAL_NOVENDOR_IFD_TYPEVENDOR_IFD_VERSIONVENDOR_NAME
Returns 0xFFFFFFFF on failure.
topGetStatusChange
Blocks execution until the current availability of the cards in a specific set of readers changes.
This function receives a list of reader names in st_reader_names. It then blocks waiting for a change in state to occur for a maximum blocking time of max_wait_ms (in milliseconds) or forever if 0 is used.
Information about the current reader states and which reader(s) changed is returned in json. See the example below for more information.
To wait for a reader event (reader added or removed) you may use the special reader name \\?PnP?\Notification.
To cancel the ongoing call, call Cancel().
The st_reader_names contains the reader names to check. The json is empty on input, and if the call returns success contains information about the state (after the event change) of each reader.
Returns error.ChilkatFailed on failure; getLastErrorText explains why.
GetStatusChangeCancel
Cancels an ongoing GetStatusChange method call. This would be called from a separate thread in your application if GetStatusChange was called synchronously.
Returns error.ChilkatFailed on failure; getLastErrorText explains why.
ListReaderGroups
Returns a list of currently available reader groups on the system. The reader groups are returned in reader_groups.
Returns error.ChilkatFailed on failure; getLastErrorText explains why.
ListReaders
Returns a list of currently available readers on the system.
Returns error.ChilkatFailed on failure; getLastErrorText explains why.
Reconnect
Reestablishes a connection to a reader that was previously connected to using Connect().
In a multi application environment it is possible for an application to reset the card in shared mode. When this occurs any other application trying to access certain commands will be returned the value SCARD_W_RESET_CARD. When this occurs Reconnect() must be called in order to acknowledge that the card was reset and allow it to change its state accordingly.
The share_mode can be shared, exclusive, or direct. The preferred_protocol can be 0 (valid only if the shareMode = direct), T0, T1, raw, or no_preference. (No preference is effectively T0 or T1.) The action is the desired action taken on the card/reader. It can be leave, reset, unpower, or eject.
If successful, the state of this object instance is that it's connected to the reader.
Returns error.ChilkatFailed on failure; getLastErrorText explains why.
ReleaseContext
Destroys a communication context to the PC/SC Resource Manager. This must be the last function called in a PC/SC application.
Returns error.ChilkatFailed on failure; getLastErrorText explains why.
SendControl
Sends a command directly to the IFD Handler (reader driver) to be processed by the reader.
This is useful for creating client side reader drivers for functions like PIN pads, biometrics, or other extensions to the normal smart card reader that are not normally handled by PC/SC.
The command data is sent in bd_send. The response is written to bd_recv.
Returns error.ChilkatFailed on failure; getLastErrorText explains why.
SendControlHex
Sends a command directly to the IFD Handler (reader driver) to be processed by the reader.
This is useful for creating client side reader drivers for functions like PIN pads, biometrics, or other extensions to the normal smart card reader that are not normally handled by PC/SC.
The command data is provided as a hex string in send_data. The response is written to bd_recv.
Returns error.ChilkatFailed on failure; getLastErrorText explains why.
Transmit
Sends an APDU to the smart card contained in the currently connected reader. The protocol_name can be T0, T1, or raw. The APDU to be sent is contained in bd_send. The response from the card is contained in bd_recv. The max_recv_len is the maximum response size (in bytes) willing to be accepted.
Returns error.ChilkatFailed on failure; getLastErrorText explains why.
TransmitHex
Sends an APDU to the smart card contained in the currently connected reader. The protocol_name can be T0, T1, or raw. The APDU (in hexadecimal) to be sent is passed in apdu_hex. The response from the card is contained in bd_recv. The max_recv_len is the maximum response size (in bytes) willing to be accepted.
Returns error.ChilkatFailed on failure; getLastErrorText explains why.
Events
All Chilkat methods are synchronous: the call returns when the work is done. During a call, SCard raises three events so your program can show progress and offer a way out. Declare any subset of abortCheck, percentDone and progressInfo in a struct of your own and install a pointer to it with setEventHandler:
const Progress = struct {
pub fn percentDone(_: *Progress, pct: i32) bool {
std.debug.print("{d}%\n", .{pct});
return false; // return true to abort the method in progress
}
pub fn progressInfo(_: *Progress, name: [:0]const u8, value: [:0]const u8) void {
std.debug.print("{s}: {s}\n", .{ name, value });
}
};
var progress = Progress{};
s_card.setEventHandler(&progress); // progress must outlive the installation
defer s_card.clearEventHandler();
s_card.setHeartbeatMs(250); // abortCheck 4 times per second during Chilkat callsInstalls handler, a pointer to any struct, as the receiver of this object's events, replacing any handler installed earlier. The dispatch is resolved at compile time: only the methods the struct declares are called, and a struct declaring none of the three is a compile error. The struct must stay alive, at the same address, until clearEventHandler or deinit.
Removes the handler; events are no longer delivered.
AbortCheck fires at regular intervals controlled by the HeartbeatMs property (0, the default, disables it); PercentDone fires when an operation's completion percentage is known; ProgressInfo delivers named progress values. Returning true from abortCheck or percentDone aborts the running method, which then returns error.ChilkatFailed.
Events fire on the thread that called the method, before that method returns. To abort a long operation from another thread, have abortCheck read a std.atomic.Value(bool), or set the object's AbortCurrent property.
AbortCheck
pub fn abortCheck(self: *T) bool
Enables a method call to be aborted by triggering the AbortCheck event at intervals defined by the HeartbeatMs property. If HeartbeatMs is set to its default value of 0, no events will occur. For instance, set HeartbeatMs to 200 to trigger 5 AbortCheck events per second.
Example
const Abort = struct {
stop: std.atomic.Value(bool) = .init(false),
pub fn abortCheck(self: *Abort) bool {
return self.stop.load(.acquire); // another thread may call abort.stop.store(true, .release)
}
};
var abort = Abort{};
s_card.setHeartbeatMs(250); // call abortCheck 4 times per second
s_card.setEventHandler(&abort);
defer s_card.clearEventHandler();PercentDone
pub fn percentDone(self: *T, pct: i32) bool
This provides the percentage completion for any method involving network communications or time-consuming processing, assuming the progress can be measured as a percentage. This event is triggered only when it's possible and logical to express the operation's progress as a percentage. The pctDone argument will range from 1 to 100. For methods that finish quickly, the number of PercentDone callbacks may vary, but the final callback will have pctDone equal to 100. For longer operations, callbacks will not exceed one per percentage point (e.g., 1, 2, 3, ..., 98, 99, 100).
The PercentDone callback also acts as an AbortCheck event. For fast methods where PercentDone fires, an AbortCheck event may not trigger since the PercentDone callback already provides an opportunity to abort. For longer operations, where time between PercentDone callbacks is extended, AbortCheck callbacks enable more responsive operation termination.
To abort the operation, set the abort output argument to true. This will cause the method to terminate and return a failure status or corresponding failure value.
Example
const Progress = struct {
pub fn percentDone(_: *Progress, pct: i32) bool {
// pct ranges from 1 to 100.
std.debug.print("Percent done: {d}\n", .{pct});
return false; // return true to abort the method in progress
}
};
var progress = Progress{};
s_card.setEventHandler(&progress);
defer s_card.clearEventHandler();ProgressInfo
pub fn progressInfo(self: *T, name: [:0]const u8, value: [:0]const u8) void
This event callback provides tag name/value pairs that detail what occurs during a method call. To discover existing tag names, create code to handle the event, emit the pairs, and review them. Most tag names are self-explanatory.
Note: Some Chilkat methods don't fire any ProgressInfo events.
Example
const Info = struct {
pub fn progressInfo(_: *Info, name: [:0]const u8, value: [:0]const u8) void {
std.debug.print("{s}: {s}\n", .{ name, value });
}
};
var info = Info{};
s_card.setEventHandler(&info);
defer s_card.clearEventHandler();